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Sample records for aggregates by relationship to concrete

  1. Assessing relationships among properties of demolished concrete, recycled aggregate and recycled aggregate concrete using regression analysis.

    Science.gov (United States)

    Tam, Vivian W Y; Wang, K; Tam, C M

    2008-04-01

    Recycled demolished concrete (DC) as recycled aggregate (RA) and recycled aggregate concrete (RAC) is generally suitable for most construction applications. Low-grade applications, including sub-base and roadwork, have been implemented in many countries; however, higher-grade activities are rarely considered. This paper examines relationships among DC characteristics, properties of their RA and strength of their RAC using regression analysis. Ten samples collected from demolition sites are examined. The results show strong correlation among the DC samples, properties of RA and RAC. It should be highlighted that inferior quality of DC will lower the quality of RA and thus their RAC. Prediction of RAC strength is also formulated from the DC characteristics and the RA properties. From that, the RAC performance from DC and RA can be estimated. In addition, RAC design requirements can also be developed at the initial stage of concrete demolition. Recommendations are also given to improve the future concreting practice.

  2. Study on conversion relationships of compressive strength indexes for recycled lightweight aggregate concrete

    Science.gov (United States)

    Zhang, Xiang-gang; Yang, Jian-hui; Kuang, Xiao-mei

    2017-01-01

    In order to study cube compressive strength and axial compressive strength of recycled lightweight aggregate concrete(RLAC), and conversion relationship between the two, with the replacement rate of recycled lightweight coarse aggregate as change parameters, 15 standard cube test specimens and 15 standard prism test specimens were produced to carry out the test. Then compressive strength of test specimens were measured, and the law of different replacement rate of recycled lightweight coarse aggregate influencing compressive strength of RLAC was analyzed, as the method of statistical regression adopted, the conversion relationships between of cube compressive strength and axial compressive strength of RLAC was obtained. It is shown that compressive strength of RLAC are lower than compressive strength of ordinary concrete; and that compressive strength of RLAC gradually decreases as replacement rate of recycled lightweight coarse aggregate increases; as well as, the conversion relationship between axial compressive strength and cube compressive strength of RLAC is different from ordinary concrete; based on the experimental data, conversion relationship formula between compressive strength indexes of RLAC was established. It is suggested that the replacement rate of recycled lightweight aggregate should be controlled within 25%.

  3. The influence of recycled concrete aggregates in pervious concrete

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    L. M. TAVARES

    Full Text Available The expansion of urban areas under constant changes in the hydrological cycle directly affects the drainage of rainwater. The problems of urban drainage become major engineering problems to be solved in order to avoid negative consequences for local populations. Another urban problem is the excessive production of construction and demolition waste (CDW, in which , even with a increasingly policy of waste management , have been an end up being thrown in inappropriate disposal sites. Alternatively aiming to a minimization of the problems presented, we propose the study of permeable concrete using recycled concrete aggregate. In this study, there were evaluated the performance of concrete by means of permeability, consistency, strength, and interface conditions of the materials . Satisfactory relationships of resistance/permeability of concrete with recycled aggregate in relation to the concrete with natural aggregates was obtained, showing their best potential.

  4. Influence of Aggregate Wettability with Different Lithology Aggregates on Concrete Drying Shrinkage

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    Yuanchen Guo

    2015-01-01

    Full Text Available The correlation of the wettability of different lithology aggregates and the drying shrinkage of concrete materials is studied, and some influential factors such as wettability and wetting angle are analyzed. A mercury porosimeter is used to measure the porosities of different lithology aggregates accurately, and the pore size ranges that significantly affect the drying shrinkage of different lithology aggregate concretes are confirmed. The pore distribution curve of the different coarse aggregates is also measured through a statistical method, and the contact angle of different coarse aggregates and concrete is calculated according to the linear fitting relationship. Research shows that concrete strength is determined by aggregate strength. Aggregate wettability is not directly correlated with concrete strength, but wettability significantly affects concrete drying shrinkage. In all types’ pores, the greatest impacts on wettability are capillary pores and gel pores, especially for the pores of the size locating 2.5–50 nm and 50–100 nm two ranges.

  5. Recycled Concrete as Aggregate for Structural Concrete Production

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    Mirjana Malešev

    2010-04-01

    Full Text Available A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC as a control concrete and two types of concrete made with natural fine and recycled coarse aggregate (50% and 100% replacement of coarse recycled aggregate. Ninety-nine specimens were made for the testing of the basic properties of hardened concrete. Load testing of reinforced concrete beams made of the investigated concrete types is also presented in the paper. Regardless of the replacement ratio, recycled aggregate concrete (RAC had a satisfactory performance, which did not differ significantly from the performance of control concrete in this experimental research. However, for this to be fulfilled, it is necessary to use quality recycled concrete coarse aggregate and to follow the specific rules for design and production of this new concrete type.

  6. Concrete produced with recycled aggregates

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    J. J. L. Tenório

    Full Text Available This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW, which were divided into recycled sand (fine and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW. The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.

  7. Sand Cement Brick Containing Recycled Concrete Aggregate as Fine-Aggregate Replacement

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    Sheikh Khalid Faisal

    2017-01-01

    Full Text Available Nowadays, the usage amount of the concrete is increasing drastically. The construction industry is a huge consumer of natural consumer. It is also producing the huge wastage products. The usage of concrete has been charged to be not environmentally friendly due to depletion of reserve natural resources, high energy consumption and disposal issues. The conservation of natural resources and reduction of disposal site by reuse and recycling waste material was interest possibilites. The aim of this study is to determine the physical and mechanical properties of sand cement brick containing recycled concrete aggregate and to determine the optimum mix ratio containing recycled concrete aggregate. An experiment done by comparing the result of control specimen using 100% natural sand with recycled concrete aggregate replacement specimen by weight for 55%, 65%, and 75%. The sample was tested under density, compressive strength, flexural strength and water absorption to study the effect of using recycled concrete aggregate on the physical and mechanical properties of bricks. The result shows that the replacement of natural sand by recycled concrete aggregate at the level of 55% provide the highest compressive and flexural strength compared to other percentage and control specimen. However, if the replacement higher than 55%, the strength of brick was decreased for compressive and flexural strength, respectively. The relationship of compressive-flexural strength is determined from statistical analysis and the predicted result can be obtained by using equation ff,RCA = 0.5375 (fc0.3272.

  8. Effect of the Aggregate Size on Strength Properties of Recycled Aggregate Concrete

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    Ma Kang

    2018-01-01

    Full Text Available The study on preparation technology of recycled concrete with economical and technical feasibility has gained more serious attention in each country due to its involvement and effect on the environment protection and the sustainable development of human society. In this study, we conducted a control variable test to investigate and assess the influence of the aggregate size on the strength characteristics of concrete with different diameters of recycled aggregates. Concrete with recycled aggregates of 5∼15 mm (A, 15∼20 mm (B, 20∼30 mm (C, and their combinations were subjected to a series of unconfined pressure tests after curing for 28 days. Based on the results obtained from the tests, an effort was made to study the relationship between the mechanical characteristics of recycled aggregate concrete and aggregate particle size. Also, a regression model of recycled concrete was proposed to predict the elasticity modulus and to adjust the design of mixture proportion. It is believed that these experiment results would contribute to adjust the remediation mixture for recycling plants by considering the influence of recycled aggregate size.

  9. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

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    Hisham Qasrawi

    2013-01-01

    Full Text Available The effect of using recycled concrete aggregates (RCA on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates has an adverse effect on the workability and air content of fresh concrete. Depending on the water/cement ratio and on the percent of the normal aggregate replaced by RCA, the concrete strength is reduced by 5% to 25%, while the tensile strength is reduced by 4% to 14%. All results are compared with previous research. As new in this research, the paper introduces a simple formula for the prediction of the modulus of elasticity of RCA concrete. Furthermore, the paper shows the variation of the air content of RAC.

  10. Recycled Concrete as Aggregate for Structural Concrete Production

    OpenAIRE

    Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

    2010-01-01

    A comparative analysis of the experimental results of the properties of fresh and hardened concrete with different replacement ratios of natural with recycled coarse aggregate is presented in the paper. Recycled aggregate was made by crushing the waste concrete of laboratory test cubes and precast concrete columns. Three types of concrete mixtures were tested: concrete made entirely with natural aggregate (NAC) as a control concrete and two types of concrete made with natural fine and recycle...

  11. Mechanical properties of recycled concrete with demolished waste concrete aggregate and clay brick aggregate

    Science.gov (United States)

    Zheng, Chaocan; Lou, Cong; Du, Geng; Li, Xiaozhen; Liu, Zhiwu; Li, Liqin

    2018-06-01

    This paper presents an experimental investigation on the effect of the replacement of natural coarse aggregate (NCA) with either recycled concrete aggregate (RCA) or recycled clay brick aggregate (RBA) on the compressive strengths of the hardened concrete. Two grades (C25 and C50) of concrete were investigated, which were achieved by using different water-to-cement ratios. In each grade concrete five different replacement rates, 0%, 25%, 50%, 75% and 100% were considered. In order to improve the performance of the recycled aggregates in the concrete mixes, the RCA and RBA were carefully sieved by using the optimal degradation. In this way the largest reduction in the 28-day compressive strength was found to be only 7.2% and 9.6% for C25 and C50 recycled concrete when the NCA was replaced 100% by RCA, and 11% and 13% for C25 and C50 recycled concrete when the NCA was replaced 100% by RBA. In general, the concrete with RCA has better performance than the concrete with RBA. The comparison of the present experimental results with those reported in literature for hardened concrete with either RCA or RBA demonstrates the effectiveness in improving the compressive strength by using the optimal gradation of recycled aggregates.

  12. Characterization of fine aggregates in concrete by different experimental approaches

    OpenAIRE

    He, Huan; Courard, Luc; Pirard, Eric; Michel, Frédéric

    2011-01-01

    Being its major component, aggregate can occupy up to three-quarter of the volume of concrete. The structure of aggregate formed in hardened state impacts largely on mechanical and durability properties of concrete. On another hand, physical characteristics of aggregate are primarily assumed to be relevant to granular behavior of aggregate. Therefore, characterization of aggregate is of high relevance to concrete studies. In this study, different types of fine aggregate used in concrete, name...

  13. Recycled concrete aggregate in portland cement concrete.

    Science.gov (United States)

    2013-01-01

    Aggregates can be produced by crushing hydraulic cement concrete and are known as recycled concrete : aggregates (RCA). This report provides results from a New Jersey Department of Transportation study to identify : barriers to the use of RCA in new ...

  14. Compressive strength and resistance to chloride ion penetration and carbonation of recycled aggregate concrete with varying amount of fly ash and fine recycled aggregate.

    Science.gov (United States)

    Sim, Jongsung; Park, Cheolwoo

    2011-11-01

    Construction and demolition waste has been dramatically increased in the last decade, and social and environmental concerns on the recycling have consequently been increased. Recent technology has greatly improved the recycling process for waste concrete. This study investigates the fundamental characteristics of concrete using recycled concrete aggregate (RCA) for its application to structural concrete members. The specimens used 100% coarse RCA, various replacement levels of natural aggregate with fine RCA, and several levels of fly ash addition. Compressive strength of mortar and concrete which used RCA gradually decreased as the amount of the recycled materials increased. Regardless of curing conditions and fly ash addition, the 28 days strength of the recycled aggregate concrete was greater than the design strength, 40 MPa, with a complete replacement of coarse aggregate and a replacement level of natural fine aggregate by fine RCA up to 60%. The recycled aggregate concrete achieved sufficient resistance to the chloride ion penetration. The measured carbonation depth did not indicate a clear relationship to the fine RCA replacement ratio but the recycled aggregate concrete could also attain adequate carbonation resistance. Based on the results from the experimental investigations, it is believed that the recycled aggregate concrete can be successfully applied to structural concrete members. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Separation and collection of coarse aggregate from waste concrete by electric pulsed power

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    Shigeishi, Mitsuhiro

    2017-09-01

    Waste concrete accounts for a substantial fraction of construction waste, and the recycling of waste concrete as concrete aggregate for construction is an important challenge associated with the rapid increase in the amount of waste concrete and the tight supply of natural aggregate. In this study, we propose a technique based on the use of high-voltage pulsed electric discharge into concrete underwater for separating and collecting aggregate from waste concrete with minimal deterioration of quality. By using this technique, the quality of the coarse aggregate separated and collected from concrete test specimens is comparable to that of coarse aggregate recycled by heating and grinding methods, thus satisfying the criteria in Japan Industrial Standard (JIS) A 5021 for the oven-dry density and the water absorption of coarse aggregate by advanced recycling.

  16. Reusing recycled aggregates in structural concrete

    Science.gov (United States)

    Kou, Shicong

    The utilization of recycled aggregates in concrete can minimize environmental impact and reduce the consumption of natural resources in concrete applications. The aim of this thesis is to provide a scientific basis for the possible use of recycled aggregates in structure concrete by conducting a comprehensive programme of laboratory study to gain a better understanding of the mechanical, microstructure and durability properties of concrete produced with recycled aggregates. The study also explored possible techniques to of improve the properties of recycled aggregate concrete that is produced with high percentages (≧ 50%) of recycled aggregates. These techniques included: (a) using lower water-to-cement ratios in the concrete mix design; (b) using fly ash as a cement replacement or as an additional mineral admixture in the concrete mixes, and (c) precasting recycled aggregate concrete with steam curing regimes. The characteristics of the recycled aggregates produced both from laboratory and a commercially operated pilot construction and demolition (C&D) waste recycling plant were first studied. A mix proportioning procedure was then established to produce six series of concrete mixtures using different percentages of recycled coarse aggregates with and without the use of fly ash. The water-to-cement (binder) ratios of 0.55, 0.50, 0.45 and 0.40 were used. The fresh properties (including slump and bleeding) of recycled aggregate concrete (RAC) were then quantified. The effects of fly ash on the fresh and hardened properties of RAC were then studied and compared with those RAC prepared with no fly ash addition. Furthermore, the effects of steam curing on the hardened properties of RAC were investigated. For micro-structural properties, the interfacial transition zones of the aggregates and the mortar/cement paste were analyzed by SEM and EDX-mapping. Moreover, a detailed set of results on the fracture properties for RAC were obtained. Based on the experimental

  17. Properties of high-workability concrete with recycled concrete aggregate

    OpenAIRE

    Safiuddin,; Alengaram,Ubagaram Johnson; Salam,Abdus; Jumaat,Mohd Zamin; Jaafar,Fahrol Fadhli; Saad,Hawa Binti

    2011-01-01

    This study presents the effects of recycled concrete aggregate (RCA) on the key fresh and hardened properties of concrete. RCA was used to produce high-workability concrete substituting 0-100% natural coarse aggregate (NCA) by weight. The slump and slump flow of fresh concretes were determined to ensure high workability. In addition, the compressive, flexural and splitting tensile strengths, modulus of elasticity, and permeable voids of hardened concretes were determined. The test results rev...

  18. Studies on recycled aggregates-based concrete.

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    Rakshvir, Major; Barai, Sudhirkumar V

    2006-06-01

    Reduced extraction of raw materials, reduced transportation cost, improved profits, reduced environmental impact and fast-depleting reserves of conventional natural aggregates has necessitated the use of recycling, in order to be able to conserve conventional natural aggregate. In this study various physical and mechanical properties of recycled concrete aggregates were examined. Recycled concrete aggregates are different from natural aggregates and concrete made from them has specific properties. The percentages of recycled concrete aggregates were varied and it was observed that properties such as compressive strength showed a decrease of up to 10% as the percentage of recycled concrete aggregates increased. Water absorption of recycled aggregates was found to be greater than natural aggregates, and this needs to be compensated during mix design.

  19. Analysis of Possibilities for Using Recycled Concrete Aggregate in Concrete Pavement

    OpenAIRE

    R. Pernicova; D. Dobias

    2016-01-01

    The present article describes the limits of using recycled concrete aggregate (denoted as RCA) in the top layer of concrete roads. The main aim of this work is to investigate the possibility of reuse of recycled aggregates obtained by crushing the old concrete roads as a building material in the new top layers of concrete pavements. The paper is based on gathering the current knowledge about how to use recycled concrete aggregate, suitability, and modification of the properties and its standa...

  20. Mechanical properties of concrete containing recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate replacement

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    Khalid, Faisal Sheikh; Azmi, Nurul Bazilah; Sumandi, Khairul Azwa Syafiq Mohd; Mazenan, Puteri Natasya

    2017-10-01

    Many construction and development activities today consume large amounts of concrete. The amount of construction waste is also increasing because of the demolition process. Much of this waste can be recycled to produce new products and increase the sustainability of construction projects. As recyclable construction wastes, concrete and ceramic can replace the natural aggregate in concrete because of their hard and strong physical properties. This research used 25%, 35%, and 45% recycled concrete aggregate (RCA) and ceramic waste as coarse aggregate in producing concrete. Several tests, such as concrete cube compression and splitting tensile tests, were also performed to determine and compare the mechanical properties of the recycled concrete with those of the normal concrete that contains 100% natural aggregate. The concrete containing 35% RCA and 35% ceramic waste showed the best properties compared with the normal concrete.

  1. Recycled aggregates concrete: aggregate and mix properties

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    González-Fonteboa, B.

    2005-09-01

    Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

    Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

  2. Relationship between the Compressive and Tensile Strength of Recycled Concrete

    International Nuclear Information System (INIS)

    El Dalati, R.; Haddad, S.; Matar, P.; Chehade, F.H

    2011-01-01

    Concrete recycling consists of crushing the concrete provided by demolishing the old constructions, and of using the resulted small pieces as aggregates in the new concrete compositions. The resulted aggregates are called recycled aggregates and the new mix of concrete containing a percentage of recycled aggregates is called recycled concrete. Our previous researches have indicated the optimal percentages of recycled aggregates to be used for different cases of recycled concrete related to the original aggregates nature. All results have shown that the concrete compressive strength is significantly reduced when using recycled aggregates. In order to obtain realistic values of compressive strength, some tests have been carried out by adding water-reducer plasticizer and a specified additional quantity of cement. The results have shown that for a limited range of plasticizer percentage, and a fixed value of additional cement, the compressive strength has reached reasonable value. This paper treats of the effect of using recycled aggregates on the tensile strength of concrete, where concrete results from the special composition defined by our previous work. The aim is to determine the relationship between the compressive and tensile strength of recycled concrete. (author)

  3. Recycled construction and demolition concrete waste as aggregate for structural concrete

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    Ashraf M. Wagih

    2013-12-01

    Full Text Available In major Egyptian cities there is a surge in construction and demolition waste (CDW quantities causing an adverse effect on the environment. The use of such waste as recycled aggregate in concrete can be useful for both environmental and economical aspects in the construction industry. This study discusses the possibility to replace natural coarse aggregate (NA with recycled concrete aggregate (RCA in structural concrete. An investigation into the properties of RCA is made using crushing and grading of concrete rubble collected from different demolition sites and landfill locations around Cairo. Aggregates used in the study were: natural sand, dolomite and crushed concretes obtained from different sources. A total of 50 concrete mixes forming eight groups were cast. Groups were designed to study the effect of recycled coarse aggregates quality/content, cement dosage, use of superplasticizer and silica fume. Tests were carried out for: compressive strength, splitting strength and elastic modulus. The results showed that the concrete rubble could be transformed into useful recycled aggregate and used in concrete production with properties suitable for most structural concrete applications in Egypt. A significant reduction in the properties of recycled aggregate concrete (RAC made of 100% RCA was seen when compared to natural aggregate concrete (NAC, while the properties of RAC made of a blend of 75% NA and 25% RCA showed no significant change in concrete properties.

  4. Natural aggregate totally replacement by mechanically treated concrete waste

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    Junak Jozef

    2015-06-01

    Full Text Available This paper presents the results obtained from the research focused on the utilization of crushed concrete waste aggregates as a partial or full replacement of 4/8 and 8/16 mm natural aggregates fraction in concrete strength class C 16/20. Main concrete characteristics such as workability, density and compressive strength were studied. Compressive strength testing intervals for samples with recycled concrete aggregates were 2, 7, 14 and 28 days. The amount of water in the mixtures was indicative. For mixture resulting consistency required slump grade S3 was followed. Average density of all samples is in the range of 2250 kg/m3 to 2350 kg/m3. The highest compressive strength after 28 days of curing, 34.68 MPa, reached sample, which contained 100% of recycled material in 4/8 mm fraction and 60% of recycled aggregates in 8/16 mm fraction. This achieved value was only slightly different from the compressive strength 34.41 MPa of the reference sample.

  5. Concrete Waste Recycling Process for High Quality Aggregate

    International Nuclear Information System (INIS)

    Ishikura, Takeshi; Fujii, Shin-ichi

    2008-01-01

    Large amount of concrete waste generates during nuclear power plant (NPP) dismantling. Non-contaminated concrete waste is assumed to be disposed in a landfill site, but that will not be the solution especially in the future, because of decreasing tendency of the site availability and natural resources. Concerning concrete recycling, demand for roadbeds and backfill tends to be less than the amount of dismantled concrete generated in a single rural site, and conventional recycled aggregate is limited of its use to non-structural concrete, because of its inferior quality to ordinary natural aggregate. Therefore, it is vital to develop high quality recycled aggregate for general uses of dismantled concrete. If recycled aggregate is available for high structural concrete, the dismantling concrete is recyclable as aggregate for industry including nuclear field. Authors developed techniques on high quality aggregate reclamation for large amount of concrete generated during NPP decommissioning. Concrete of NPP buildings has good features for recycling aggregate; large quantity of high quality aggregate from same origin, record keeping of the aggregate origin, and little impurities in dismantled concrete such as wood and plastics. The target of recycled aggregate in this development is to meet the quality criteria for NPP concrete as prescribed in JASS 5N 'Specification for Nuclear Power Facility Reinforced Concrete' and JASS 5 'Specification for Reinforced Concrete Work'. The target of recycled aggregate concrete is to be comparable performance with ordinary aggregate concrete. The high quality recycled aggregate production techniques are assumed to apply for recycling for large amount of non-contaminated concrete. These techniques can also be applied for slightly contaminated concrete dismantled from radiological control area (RCA), together with free release survey. In conclusion: a technology on dismantled concrete recycling for high quality aggregate was developed

  6. Compressive strength improvement for recycled concrete aggregate

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    Mohammed Dhiyaa

    2018-01-01

    Full Text Available Increasing amount of construction waste and, concrete remnants, in particular pose a serious problem. Concrete waste exist in large amounts, do not decay and need long time for disintegration. Therefore, in this work old demolished concrete is crashed and recycled to produce recycled concrete aggregate which can be reused in new concrete production. The effect of using recycled aggregate on concrete compressive strength has been experimentally investigated; silica fume admixture also is used to improve recycled concrete aggregate compressive strength. The main parameters in this study are recycled aggregate and silica fume admixture. The percent of recycled aggregate ranged from (0-100 %. While the silica fume ranged from (0-10 %. The experimental results show that the average concrete compressive strength decreases from 30.85 MPa to 17.58 MPa when the recycled aggregate percentage increased from 0% to 100%. While, when silica fume is used the concrete compressive strength increase again to 29.2 MPa for samples with 100% of recycled aggregate.

  7. Influence of uncoated and coated plastic waste coarse aggregates to concrete compressive strength

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    Purnomo Heru

    2017-01-01

    Full Text Available The use of plastic waste as coarse aggregates in concrete is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of the concrete than concrete using natural aggregates, but on the other hand bond between plastic coarse aggregates and hard matrix give low concrete compressive strength. Improvement of the bond between plastic coarse aggregate and hard matrix through a sand coating to plastic coarse aggregate whole surface is studied. Sand used to coat the plastic aggregates are Merapi volcanic sand which are taken in Magelang. Three mixtures of polypropylene (PP coarse plastic aggregates, Cimangkok river sand as fine aggregates, water and Portland Cement Composite with a water-cement ratio of 0.28, 0.3 and 0.35 are conducted. Compression test are performed on concrete cylindrical specimens with a diameter of 10 cm and a height of 20 cm. The results in general show that concrete specimens using plastic aggregates coated with sand have higher compressive strength compared to those of concrete specimens using plastic aggregates without sand coating. The bond improvement is indirectly indicated by the betterment of concrete compressive strength.

  8. Effect of water absorption by the aggregate on properties of high-strength lightweight concrete

    Energy Technology Data Exchange (ETDEWEB)

    Punkki, J

    1996-12-31

    Recently, high-strength lightweight concrete has become an interesting building material for the offshore oil industry. This doctoral thesis presents an experimental investigation of the effect of water absorption by three different types of lightweight aggregates. One type did not show any water absorption ability at all and so represented no problem to the concrete production. For the two other high-strength aggregates, which were of more conventional types, the water absorption depended not only on the properties of the aggregates, but also on the concrete mixing procedure and the properties of the fresh cement paste. When water absorbing lightweight aggregate was used in a dry condition, the workability of the concrete was significantly reduced by the water absorption of the aggregate. This effect was not present when prewetted aggregate was used. The water absorption by the lightweight aggregate also affected the early compressive strength of concrete. After one day, dry aggregate gave on the average 10 MPa higher compressive strength than did prewetted aggregate. The strength-density ratio was affected by the moisture condition of the aggregate. Dry lightweight aggregate gave 9 MPa higher compressive strength at a density of 2000 kg/m{sup 3} compared to that of prewetted aggregate. The water absorption by the lightweight also affected the microstructure of the hardened concrete. Dry lightweight aggregate gave a slightly better microstructure than normal weight aggregate. The results indicate that the use of prewetted aggregate adversely affected the transition zone between the aggregate and the cement paste. 69 refs., 58 figs., 42 tabs.

  9. Effect of water absorption by the aggregate on properties of high-strength lightweight concrete

    Energy Technology Data Exchange (ETDEWEB)

    Punkki, J.

    1995-12-31

    Recently, high-strength lightweight concrete has become an interesting building material for the offshore oil industry. This doctoral thesis presents an experimental investigation of the effect of water absorption by three different types of lightweight aggregates. One type did not show any water absorption ability at all and so represented no problem to the concrete production. For the two other high-strength aggregates, which were of more conventional types, the water absorption depended not only on the properties of the aggregates, but also on the concrete mixing procedure and the properties of the fresh cement paste. When water absorbing lightweight aggregate was used in a dry condition, the workability of the concrete was significantly reduced by the water absorption of the aggregate. This effect was not present when prewetted aggregate was used. The water absorption by the lightweight aggregate also affected the early compressive strength of concrete. After one day, dry aggregate gave on the average 10 MPa higher compressive strength than did prewetted aggregate. The strength-density ratio was affected by the moisture condition of the aggregate. Dry lightweight aggregate gave 9 MPa higher compressive strength at a density of 2000 kg/m{sup 3} compared to that of prewetted aggregate. The water absorption by the lightweight also affected the microstructure of the hardened concrete. Dry lightweight aggregate gave a slightly better microstructure than normal weight aggregate. The results indicate that the use of prewetted aggregate adversely affected the transition zone between the aggregate and the cement paste. 69 refs., 58 figs., 42 tabs.

  10. Behaviour of Recycled Coarse Aggregate Concrete: Age and Successive Recycling

    Science.gov (United States)

    Sahoo, Kirtikanta; Pathappilly, Robin Davis; Sarkar, Pradip

    2016-06-01

    Recycled Coarse Aggregate (RCA) concrete construction technique can be called as `green concrete', as it minimizes the environmental hazard of the concrete waste disposal. Indian standard recommends target mean compressive strength of the conventional concrete in terms of water cement ratio ( w/ c). The present work is an attempt to study the behaviour of RCA concrete from two samples of parent concrete having different age group with regard to the relationship of compressive strength with water cement ratios. Number of recycling may influence the mechanical properties of RCA concrete. The influence of age and successive recycling on the properties such as capillary water absorption, drying shrinkage strain, air content, flexural strength and tensile splitting strength of the RCA concrete are examined. The relationship between compressive strength at different w/ c ratios obtained experimentally is investigated for the two parameters such as age of parent concrete and successive recycling. The recycled concrete using older recycled aggregate shows poor quality. While the compressive strength reduces with successive recycling gradually, the capillary water absorption increases abruptly, which leads to the conclusion that further recycling may not be advisable.

  11. Evaluation of recycled concrete as aggregate in new concrete pavements.

    Science.gov (United States)

    2014-04-01

    This study evaluated the use of recycled concrete as coarse aggregate in new concrete pavements. : Recycled concrete aggregate (RCA) produced from demolished pavements in three geographically dispersed locations in Washington state were used to perfo...

  12. Strength of masonry blocks made with recycled concrete aggregates

    Science.gov (United States)

    Matar, Pierre; Dalati, Rouba El

    The idea of recycling concrete of demolished buildings aims at preserving the environment. Indeed, the reuse of concrete as aggregate in new concrete mixes helped to reduce the expenses related to construction and demolition (C&D) waste management and, especially, to protect the environment by reducing the development rate of new quarries. This paper presents the results of an experimental study conducted on masonry blocks containing aggregates resulting from concrete recycling. The purpose of this study is to investigate the effect of recycled aggregates on compressive strength of concrete blocks. Tests were performed on series of concrete blocks: five series each made of different proportions of recycled aggregates, and one series of reference blocks exclusively composed of natural aggregates. Tests showed that using recycled aggregates with addition of cement allows the production of concrete blocks with compressive strengths comparable to those obtained on concrete blocks made exclusively of natural aggregates.

  13. Concrete manufacture with un-graded recycled aggregates

    OpenAIRE

    Richardson, Alan; Coventry, Kathryn; Graham, Sue

    2009-01-01

    Purpose – The purpose of this paper is to investigate whether concrete that includes un-graded recycled aggregates can be manufactured to a comparable strength to concrete manufactured from virgin aggregates. \\ud \\ud Design/methodology/approach – A paired comparison test was used to evaluate the difference between concrete made with virgin aggregates (plain control) and concrete including recycled waste. Un-graded construction demolition waste and un-graded ground glass were used as aggregate...

  14. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates.

    Science.gov (United States)

    Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B

    2015-01-01

    Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

  15. Properties of concrete with tire derived aggregate and crumb rubber as a lighthweight substitute for mineral aggregates in the concrete mix

    Science.gov (United States)

    Siringi, Gideon Momanyi

    Scrap tires continue to be a nuisance to the environment and this research proposes one way of recycling them as a lightweight aggregate which can substitute for mineral aggregates in concrete. Aggregates derived from scrap tires are often referred to as Tire Derived Aggregate (TDA). First, the focus is how much mineral aggregate can be replaced by these waste tires and how the properties of concrete are affected with the introduction of rubber. This is being mindful of the fact that for a new material to be acceptable as an engineering material, its properties and behavior has to be well understood, the materials must perform properly and be acceptable to the regulating agencies. The role played by the quantity of TDA and Crumb Rubber replacing coarse aggregate and fine aggregate respectively as well as different treatment and additives in concrete on its properties are examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, Splitting Tensile Strength based on ASTM C496, Modulus of Rupture (flexural strength) based on ASTM C78 and Bond strength of concrete developed with reinforcing steel based on ASTM C234.Through stress-strain plots, the rubberized concrete is compared in terms of change in ductility, toughness and Elastic Modulus. Results indicate that while replacement of mineral aggregates with TDA results in reduction in compressive strength, this may be mitigated by addition of silica fume or using a smaller size of TDA to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product with lower density while utilizing recycled TDA. From the results, it is observed that 7-10% of weight of mineral aggregates can be replaced by an equal volume of TDA to produce concrete with compressive strength of up to 4000 psi (27.5 MPa). Rubberized concrete would have higher ductility and toughness with

  16. Recycled aggregates in concrete production: engineering properties and environmental impact

    Directory of Open Access Journals (Sweden)

    Seddik Meddah Mohammed

    2017-01-01

    Full Text Available Recycled concrete aggregate is considered as the most abundant and used secondary aggregate in concrete production, other types of solid waste are also being used in concrete for specific purposes and to achieve some desired properties. Recycled aggregates and particularly, recycled concrete aggregate substantially affect the properties and mix design of concrete both at fresh and hardened states since it is known by high porosity due to the adhered layer of old mortar on the aggregate which results in a high water absorption of the recycled secondary aggregate. This leads to lower density and strength, and other durability related properties. The use of most recycled aggregate in concrete structures is still limited to low strength and non-structural applications due to important drop in strength and durability performances generated. Embedding recycled aggregates in concrete is now a current practice in many countries to enhance sustainability of concrete industry and reduce its environmental impacts. The present paper discusses the various possible recycled aggregates used in concrete production, their effect on both fresh and hardened properties as well as durability performances. The economic and environmental impacts of partially or fully substituting natural aggregates by secondary recycled aggregates are also discussed.

  17. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

    Science.gov (United States)

    Siringi, Gideon; Abolmaali, Ali; Aswath, Pranesh B.

    2015-01-01

    Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength) based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA. PMID:26161440

  18. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

    Directory of Open Access Journals (Sweden)

    Gideon Siringi

    2015-01-01

    Full Text Available Tire derived aggregate (TDA has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

  19. Recycled aggregates in concrete production: engineering properties and environmental impact

    OpenAIRE

    Seddik Meddah Mohammed

    2017-01-01

    Recycled concrete aggregate is considered as the most abundant and used secondary aggregate in concrete production, other types of solid waste are also being used in concrete for specific purposes and to achieve some desired properties. Recycled aggregates and particularly, recycled concrete aggregate substantially affect the properties and mix design of concrete both at fresh and hardened states since it is known by high porosity due to the adhered layer of old mortar on the aggregate which ...

  20. Concrete with onyx waste aggregate as aesthetically valued structural concrete

    Science.gov (United States)

    Setyowati E., W.; Soehardjono, A.; Wisnumurti

    2017-09-01

    The utillization of Tulungagung onyx stone waste as an aggregate of concrete mixture will improve the economic value of the concrete due to the brighter color and high aesthetic level of the products. We conducted the research of 75 samples as a test objects to measure the compression stress, splits tensile stress, flexural tensile stress, elasticity modulus, porosity modulus and also studied 15 test objects to identify the concrete micro structures using XRD test, EDAX test and SEM test. The test objects were made from mix designed concrete, having ratio cement : fine aggregate : coarse aggregate ratio = 1 : 1.5 : 2.1, and W/C ratio = 0.4. The 28 days examination results showed that the micro structure of Tulungagung onyx waste concrete is similar with normal concrete. Moreover, the mechanical test results proved that Tulungagung onyx waste concretes also have a qualified level of strength to be used as a structural concrete with higher aesthetic level.

  1. Microstructural characterization of concrete prepared with recycled aggregates.

    Science.gov (United States)

    Guedes, Mafalda; Evangelista, Luís; de Brito, Jorge; Ferro, Alberto C

    2013-10-01

    Several authors have reported the workability, mechanical properties, and durability of concrete produced with construction waste replacing the natural aggregate. However, a systematic microstructural characterization of recycled aggregate concrete has not been reported. This work studies the use of fine recycled aggregate to replace fine natural aggregate in the production of concrete and reports the resulting microstructures. The used raw materials were natural aggregate, recycled aggregate obtained from a standard concrete, and Portland cement. The substitution extent was 0, 10, 50, and 100 vol%; hydration was stopped at 9, 24, and 96 h and 28 days. Microscopy was focused on the cement/aggregate interfacial transition zone, enlightening the effect of incorporating recycled aggregate on the formation and morphology of the different concrete hydration products. The results show that concretes with recycled aggregates exhibit typical microstructural features of the transition zone in normal strength concrete. Although overall porosity increases with increasing replacement, the interfacial bond is apparently stronger when recycled aggregates are used. An addition of 10 vol% results in a decrease in porosity at the interface with a corresponding increase of the material hardness. This provides an opportunity for development of increased strength Portland cement concretes using controlled amounts of concrete waste.

  2. The alkali-aggregate reaction - concrete microstructure evolution

    International Nuclear Information System (INIS)

    Regourd, M.; Hornain, H.; Poitevin, P.

    1981-01-01

    The alkali-aggregate reaction has been studied by scanning electron microscopy and energy dispersive X-ray analysis, electron probe microanalysis, and X-ray diffraction in concretes containing glass aggregates or hornfels and greywacke aggregates. The surface reaction of the natural aggregates in alkaline solutions has been analysed by X-ray photo-electron spectrometry. The study of concretes with glass aggregates stored at 20 degrees Celcius and 100 percent relative humidity has revealed, irrespective of alkali content and type of cement, the formation of a gel containing SiO 2 , Na 2 O, CaO, MgO and Al 2 O 3 . Under heat and pressure (210 degrees Celcius at MPa for 48 hours), the gel crystallizes and yields silicates not very different from tobermorite found in autoclaved normal concretes but cotaining Na and K in solid solutions. The alkali reaction in two natural aggregate concretes, is also shown by the formation of gels and silicate crystals. The progressive structuring of the gels in silicate crystals is promoted by an increase in temperature. Ettringite and Ca(OH) 2 reinforce the alkali-aggregate reaction which may be looked upon as a hydration reaction, partially of the pozzolanic type

  3. Influence of uncoated and coated plastic waste coarse aggregates to concrete compressive strength

    OpenAIRE

    Purnomo Heru; Pamudji Gandjar; Satim Madsuri

    2017-01-01

    The use of plastic waste as coarse aggregates in concrete is part of efforts to reduce environmental pollution. In one hand the use of plastic as aggregates can provide lighter weight of the concrete than concrete using natural aggregates, but on the other hand bond between plastic coarse aggregates and hard matrix give low concrete compressive strength. Improvement of the bond between plastic coarse aggregate and hard matrix through a sand coating to plastic coarse aggregate whole surface is...

  4. Utilisation of iron ore tailings as aggregates in concrete

    Directory of Open Access Journals (Sweden)

    Francis Atta Kuranchie

    2015-12-01

    Full Text Available Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength were tested. A controlled mix of concrete was also prepared in similar way using conventional materials and the results were compared with the tailings concrete. It was found that the iron ore tailings may be utilised for complete replacement for conventional aggregates in concrete. The iron ore tailings aggregates concrete exhibited a good mechanical strength and even in the case of compressive strength, there was an improvement of 11.56% over conventional aggregates concrete. The indirect tensile strength did not improve against the control mix due high content of fines in the tailings aggregates but showed 4.8% improvement compared with the previous study where the conventional fine aggregates was partially replaced by 20% with iron ore tailings.

  5. A study of concrete properties using phyllite as coarse aggregates

    International Nuclear Information System (INIS)

    Adom-Asamoah, Mark; Afrifa, Russell Owusu

    2010-01-01

    Nowadays, industrial activities generate a huge amount of waste. One such activity is underground mining which generates phyllite wastes that are recycled as coarse aggregates for use in concrete production. Aggregate use in concrete is dependent on availability. This paper reports of an experimental study on some of the physical and mechanical properties of phyllite aggregate concrete as compared to granite (conventional) aggregate concrete. The obtained physical and mechanical properties of both aggregates for specific gravity, water absorption (%), dry density, aggregate impact value (%), aggregate crushing value (%), 10% fines, elongation index (%), flakiness index (%) and Los Angeles abrasion values satisfied minimum requirements for aggregates suitable for concrete production. Five mixes of concrete mix proportions designated M1, M2, M3, M4 and M5 were cast using phyllite and granite aggregates. A total of 400 concrete cubes and 210 modulus of rupture beams were cast and cured by total submerging in water for ages 3, 7, 14, 28, 56, 90, 180 and 360 days before compression and bending tests were performed. The results show that the trends in the development of compressive and bending strengths of plain phyllite concrete were similar to those in granite (conventional) aggregate concrete. However the compressive and bending strengths of phyllite concrete mixes were on the average 15-20% lower than those of the corresponding granite concrete mixes at all ages. The same concrete mix proportions gave lower concrete classes for phyllite compared to granite with the exception of the lowest grade. This was probably because the flakiness and elongation properties coupled with reactive materials in phyllite aggregates affect the absorption and bond characteristics of its concrete.

  6. SHAPE CHARACTERIZATION OF CONCRETE AGGREGATE

    Directory of Open Access Journals (Sweden)

    Jing Hu

    2011-05-01

    Full Text Available As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ is assumed to be different from the bulk material. In general, properties of conventional concrete have been found favoured by optimum packing density of the aggregate. Particle size is a common denominator in such studies. Size segregation in the ITZ among the binder particles in the fresh state, observed in simulation studies by concurrent algorithm-based SPACE system, additionally governs density as well as physical bonding capacity inside these shell-like zones around aggregate particles. These characteristics have been demonstrated qualitatively pertaining also after maturation of the concrete. Such properties of the ITZs have direct impact on composite properties. Despite experimental approaches revealed effects of aggregate grain shape on different features of material structure (among which density, and as a consequence on mechanical properties, it is still an underrated factor in laboratory studies, probably due to the general feeling that a suitable methodology for shape characterization is not available. A scientific argument hindering progress is the interconnected nature of size and shape. Presently, a practical problem preventing shape effects to be emphasized is the limitation of most computer simulation systems in concrete technology to spherical particles. New developments at Delft University of Technology will make it possible in the near future to generate jammed states, or other high-density fresh particle mixtures of non-spherical particles, which thereupon can be subjected to hydration algorithms. This paper will sketch the outlines of a methodological approach for shape assessment of loose (non-embedded aggregate grains, and demonstrate its use for two types of aggregate, allowing

  7. Utilization of recycled concrete aggregates in structural concrete by applying a fraction partitioning model

    NARCIS (Netherlands)

    Wouw, van de P.M.F.; Doudart de la Grée, G.C.H.; Florea, M.V.A.; Brouwers, H.J.H.; Bilek, V.; Kersner, Z.

    2014-01-01

    The recycling of concrete waste into new structural concrete reduces the utilization of raw materials, decreases transport and production energy cost, and saves the use of limited landfill space. Currently, recycling involves the use of recycled concrete aggregates (RCA) as road base material or in

  8. Recycling of PET bottles as fine aggregate in concrete

    International Nuclear Information System (INIS)

    Frigione, Mariaenrica

    2010-01-01

    An attempt to substitute in concrete the 5% by weight of fine aggregate (natural sand) with an equal weight of PET aggregates manufactured from the waste un-washed PET bottles (WPET), is presented. The WPET particles possessed a granulometry similar to that of the substituted sand. Specimens with different cement content and water/cement ratio were manufactured. Rheological characterization on fresh concrete and mechanical tests at the ages of 28 and 365 days were performed on the WPET/concretes as well as on reference concretes containing only natural fine aggregate in order to investigate the influence of the substitution of WPET to the fine aggregate in concrete. It was found that the WPET concretes display similar workability characteristics, compressive strength and splitting tensile strength slightly lower that the reference concrete and a moderately higher ductility.

  9. Properties of concretes produced with waste concrete aggregate

    International Nuclear Information System (INIS)

    Topcu, Ilker Bekir; Sengel, Selim

    2004-01-01

    An environmentally friendly approach to the disposal of waste materials, a difficult issue to cope with in today's world, would only be possible through a useful recycling process. For this reason, we suggest that clearing the debris from destroyed buildings in such a way as to obtain waste concrete aggregates (WCA) to be reused in concrete production could well be a partial solution to environmental pollution. For this study, the physical and mechanical properties along with their freeze-thaw durability of concrete produced with WCAs were investigated and test results presented. While experimenting with fresh and hardened concrete, mixtures containing recycled concrete aggregates in amounts of 30%, 50%, 70%, and 100% were prepared. Afterward, these mixtures underwent freeze-thaw cycles. As a result, we found out that C16-quality concrete could be produced using less then 30% C14-quality WCA. Moreover, it was observed that the unit weight, workability, and durability of the concretes produced through WCA decreased in inverse proportion to their endurance for freeze-thaw cycle

  10. Leaching assessment of concrete made of recycled coarse aggregate: physical and environmental characterisation of aggregates and hardened concrete.

    Science.gov (United States)

    Galvín, A P; Agrela, F; Ayuso, J; Beltrán, M G; Barbudo, A

    2014-09-01

    Each year, millions of tonnes of waste are generated worldwide, partially through the construction and demolition of buildings. Recycling the resulting waste could reduce the amount of materials that need to be manufactured. Accordingly, the present work has analysed the potential reuse of construction waste in concrete manufacturing by replacing the natural aggregate with recycled concrete coarse aggregate. However, incorporating alternative materials in concrete manufacturing may increase the pollutant potential of the product, presenting an environmental risk via ground water contamination. The present work has tested two types of concrete batches that were manufactured with different replacement percentages. The experimental procedure analyses not only the effect of the portion of recycled aggregate on the physical properties of concrete but also on the leaching behaviour as indicative of the contamination degree. Thus, parameters such as slump, density, porosity and absorption of hardened concrete, were studied. Leaching behaviour was evaluated based on the availability test performed to three aggregates (raw materials of the concrete batches) and on the diffusion test performed to all concrete. From an environmental point of view, the question of whether the cumulative amount of heavy metals that are released by diffusion reaches the availability threshold was answered. The analysis of concentration levels allowed the establishment of different groups of metals according to the observed behaviour, the analysis of the role of pH and the identification of the main release mechanisms. Finally, through a statistical analysis, physical parameters and diffusion data were interrelated. It allowed estimating the relevance of porosity, density and absorption of hardened concrete on diffusion release of the metals in study. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Recycling of PET bottles as fine aggregate in concrete.

    Science.gov (United States)

    Frigione, Mariaenrica

    2010-06-01

    An attempt to substitute in concrete the 5% by weight of fine aggregate (natural sand) with an equal weight of PET aggregates manufactured from the waste un-washed PET bottles (WPET), is presented. The WPET particles possessed a granulometry similar to that of the substituted sand. Specimens with different cement content and water/cement ratio were manufactured. Rheological characterization on fresh concrete and mechanical tests at the ages of 28 and 365days were performed on the WPET/concretes as well as on reference concretes containing only natural fine aggregate in order to investigate the influence of the substitution of WPET to the fine aggregate in concrete. It was found that the WPET concretes display similar workability characteristics, compressive strength and splitting tensile strength slightly lower that the reference concrete and a moderately higher ductility. Copyright 2010 Elsevier Ltd. All rights reserved.

  12. Concrete = aggregate, cement, water?

    International Nuclear Information System (INIS)

    Jelinek, J.

    1990-01-01

    Concrete for the Temelin nuclear power plant is produced to about 70 different formulae. For quality production, homogeneous properties of aggregates, accurate proportioning devices, technological discipline and systematic inspections and tests should be assured. The results are reported of measuring compression strength after 28 days for different concrete samples. The results of such tests allow reducing the proportion of cement, which brings about considerable savings. Reduction in cement quantities can also be achieved by adding ash to the concrete mixes. Ligoplast, a plasticizer addition is used for improving workability. (M.D). 8 figs

  13. Environmental performance and mechanical analysis of concrete containing recycled asphalt pavement (RAP) and waste precast concrete as aggregate.

    Science.gov (United States)

    Erdem, Savaş; Blankson, Marva Angela

    2014-01-15

    The overall objective of this research project was to investigate the feasibility of incorporating 100% recycled aggregates, either waste precast concrete or waste asphalt planning, as replacements for virgin aggregates in structural concrete and to determine the mechanical and environmental performance of concrete containing these aggregates. Four different types of concrete mixtures were designed with the same total water cement ratio (w/c=0.74) either by using natural aggregate as reference or by totally replacing the natural aggregate with recycled material. Ground granulated blast furnace slag (GGBS) was used as a mineral addition (35%) in all mixtures. The test results showed that it is possible to obtain satisfactory performance for strength characteristics of concrete containing recycled aggregates, if these aggregates are sourced from old precast concrete. However, from the perspective of the mechanical properties, the test results indicated that concrete with RAP aggregate cannot be used for structural applications. In terms of leaching, the results also showed that the environmental behaviour of the recycled aggregate concrete is similar to that of the natural aggregate concrete. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Acid resistance of quaternary blended recycled aggregate concrete

    Directory of Open Access Journals (Sweden)

    K Jagannadha Rao

    2018-06-01

    Full Text Available The possibility of reusing the aggregate from demolished structures in fresh concrete, in order to reduce the CO2 impact on the environment [23] and to preserve natural resources, was explored worldwide and it is established that recycled aggregates can be used as a partial replacement of natural aggregates. Due to its potential to be used in eco-friendly structures and shortage of supply of natural aggregates in some parts of the world, there is an increasing interest in using the recycled aggregate. The durability aspects are also of equal concern along with the strength and economy of any material to be used in the construction. Studies reveal that the behaviour of ternary and quaternary blended concretes is superior from durability point of view compared to conventional concrete. Therefore a study is conducted to assess the acid resistance of recycled aggregate based Quaternary Blended Cement Concrete (QBCC of two grades M40 and M60. Fly ash and silica fume are fixed at 20% and 10% respectively from the previous studies while two percentages of Nano silica (2 and 3% were used along with the cement to obtain QBCC. Three percentages of recycled aggregates as partial replacement of conventional aggregate (0%, 50% and 75% were used in this study. Two different acids (HCL and H2SO4 with different concentrations (3 and 5% were used in this study. Acid resistance of QBCC with Recycled Concrete Aggregate (RCA is assessed in terms of visual appearance, weight loss, and compressive strength loss by destructive and non-destructive tests at regular intervals for a period of 56 days. The test results showed marginal weight loss and strength loss in both M40 and M60 grades of concretes. The Ultrasonic Pulse Velocity (UPV results show that the quality of QBCC is good even after being subjected to acid exposure. Keywords: Recycled concrete aggregate (RCA, Quaternary blended cement concrete (QBCC, Acid resistance, Ultrasonic pulse velocity (UPV, Mineral

  15. Alkali Release from Typical Danish Aggregates to Potential ASR Reactive Concrete

    DEFF Research Database (Denmark)

    Thomsen, Hans Christian Brolin; Grelk, Bent; Barbosa, Ricardo Antonio

    Alkali-silica reaction (ASR) in concrete is a well-known deterioration mechanism affecting the long term durability of Danish concrete structures. Deleterious ASR cracking can be significantly reduced or prevented by limiting the total alkali content of concrete under a certain threshold limit......, which in Denmark is recommended to 3 kg/m3 Na2Oeq.. However, this threshold limit does not account for the possible internal contribution of alkali to the concrete pore solution by release from aggregates or external contributions from varies sources. This study indicates that certain Danish aggregates...... are capable of releasing more than 0.46 kg/m3 Na2Oeq. at 13 weeks of exposure in laboratory test which may increase the risk for deleterious cracking due to an increase in alkali content in the concrete....

  16. Study on Concrete Containing Recycled Aggregates Immersed in Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Adnan Suraya Hani

    2017-01-01

    Full Text Available In recent decades, engineers have sought a more sustainable method to dispose of concrete construction and demolition waste. One solution is to crush this waste concrete into a usable gradation for new concrete mixes. This not only reduces the amount of waste entering landfills but also alleviates the burden on existing sources of quality natural concrete aggregates. There are too many kinds of waste but here constructions waste will be the priority target that should be solved. It could be managed by several ways such as recycling and reusing the concrete components, and the best choice of these components is the aggregate, because of the ease process of recycle it. In addition, recycled aggregates and normal aggregates were immersed in epoxy resin and put in concrete mixtures with 0%, 5%, 10% and 20% which affected the concrete mixtures properties. The strength of the concrete for both normal and recycled aggregates has increased after immersed the aggregates in epoxy resin. The percentage of water absorption and the coefficient of water permeability decreased with the increasing of the normal and the recycled aggregates immersed in epoxy resin. Generally the tests which have been conducted to the concrete mixtures have a significant results after using the epoxy resin with both normal and recycled aggregates.

  17. Aspects Concerning the Use of Recycled Concrete Aggregates

    Science.gov (United States)

    Robu, I.; Mazilu, C.; Deju, R.

    2016-11-01

    Natural aggregates (gravel and crushed) are essential non-renewable resources which are used for infrastructure works and civil engineering. Using recycled concrete aggregates (RCA) is a matter of high priority in the construction industry worldwide. This paper presents a study on the use of recycled aggregates, from a concrete of specified class, to acquire new cement concrete with different percentages of recycled aggregates.

  18. The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

    OpenAIRE

    Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

    2014-01-01

    In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were...

  19. The material from Lampung as coarse aggregate to substitute andesite for concrete-making

    Science.gov (United States)

    Amin, M.; Supriyatna, Y. I.; Sumardi, S.

    2018-01-01

    Andesite stone is usually used for split stone material in the concrete making. However, its availability is decreasing. Lampung province has natural resources that can be used for coarse aggregate materials to substitute andesite stone. These natural materials include limestone, feldspar stone, basalt, granite, and slags from iron processing waste. Therefore, a research on optimizing natural materials in Lampung to substitute andesite stone for concrete making is required. This research used laboratory experiment method. The research activities included making cubical object samples of 150 x 150 x 150 mm with material composition referring to a standard of K.200 and w/c 0.61. Concrete making by using varying types of aggregates (basalt, limestone, slag) and aggregate sizes (A = 5-15 mm, B = 15-25 mm, and 25-50 mm) was followed by compressive strength test. The results showed that the obtained optimal compressive strengths for basalt were 24.47 MPa for 50-150 mm aggregate sizes, 21.2 MPa for 15-25 mm aggregate sizes, and 20.7 MPa for 25-50 mm aggregate sizes. These results of basalt compressive strength values were higher than the same result for andesite (19.69 MPa for 50-150 mm aggregate sizes), slag (22.72 MPa for 50-150 mm aggregate sizes), and limestone (19.69 Mpa for 50-150 mm aggregate sizes). These results indicated that basalt, limestone, and slag aggregates were good enough to substitute andesite as materials for concrete making. Therefore, natural resources in Lampung can be optimized as construction materials in concrete making.

  20. Study of recycled concrete aggregate quality and its relationship with recycled concrete compressive strength using database analysis

    Directory of Open Access Journals (Sweden)

    González-Taboada, I.

    2016-09-01

    Full Text Available This work studies the physical and mechanical properties of recycled concrete aggregate (recycled aggregate from concrete waste and their influence in structural recycled concrete compressive strength. For said purpose, a database has been developed with the experimental results of 152 works selected from over 250 international references. The processed database results indicate that the most sensitive properties of recycled aggregate quality are density and absorption. Moreover, the study analyses how the recycled aggregate (both percentage and quality and the mixing procedure (pre-soaking or adding extra water influence the recycled concrete strength of different categories (high or low water to cement ratios. When recycled aggregate absorption is low (under 5%, pre-soaking or adding extra water to avoid loss in workability will negatively affect concrete strength (due to the bleeding effect, whereas with high water absorption this does not occur and both of the aforementioned correcting methods can be accurately employed.El estudio analiza las propiedades físico-mecánicas de los áridos reciclados de hormigón (procedentes de residuos de hormigón y su influencia en la resistencia a compresión del hormigón reciclado estructural. Para ello se ha desarrollado una base de datos con resultados de 152 trabajos seleccionados a partir de más de 250 referencias internacionales. Los resultados del tratamiento de la base indican que densidad y absorción son las propiedades más sensibles a la calidad del árido reciclado. Además, este estudio analiza cómo el árido reciclado (porcentaje y calidad y el procedimiento de mezcla (presaturación o adición de agua extra influyen en la resistencia del hormigón reciclado de diferentes categorías (alta o baja relación agua-cemento. Cuando la absorción es baja (inferior al 5% presaturar o añadir agua para evitar pérdidas de trabajabilidad afectan negativamente a la resistencia (debido al bleeding

  1. Study on Mechanical Properties of Concrete Using Plastic Waste as an Aggregate

    Science.gov (United States)

    Jaivignesh, B.; Sofi, A.

    2017-07-01

    Disposal of large quantity of plastic causes land, water and air pollution etc.., so a study is conducted to recycle the plastic in concrete. This work investigates about the replacement of natural aggregate with non-biodegradable plastic aggregate made up of mixed plastic waste in concrete. Several tests are conducted such as compressive strength of cube, split tensile strength of cylinder, flexural strength test of prism to identify the properties and behavior of concrete using plastic aggregate. Replacement of fine aggregate weight by 10%, 15%, 20% with Plastic fine (PF) aggregate and for each replacement of fine aggregate 15%, 20%, 25% of coarse aggregate replacement also conducted with Plastic Coarse(PC) aggregate. In literatures reported that the addition of plastic aggregate in concrete causes the reduction of strength in concrete due to poor bonding between concrete and plastic aggregate, so addition of 0.3% of steel fiber by weight of cement in concrete is done to improve the concrete strength. Totally 60 cubes, 60 cylinders and 40 prisms are casted to identify the compressive strength, split tensile strength and flexural strength respectively. Casted specimens are tested at 7 and 28 days. The identified results from concrete using plastic aggregate are compared with conventional concrete. Result shows that reduction in mechanical properties of plastic aggregate added concrete. This reduction in strength is mainly due to poor bond strength between cement and plastic aggregate.

  2. Ceramic ware waste as coarse aggregate for structural concrete production.

    Science.gov (United States)

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

  3. Alkali aggregate reactivity in concrete structures in western Canada

    International Nuclear Information System (INIS)

    Morgan, D.R.; Empey, D.

    1989-01-01

    In several regions of Canada, particularly parts of Ontario, Quebec and the Maritime Provinces, research, testing and evaluation of aged concrete structures in the field has shown that alkali aggregate reactivity can give rise to pronounced concrete deterioration, particularly in hydraulic structures subjected to saturation or alternate wetting and drying such as locks, dams, canals, etc. Concrete deterioration is mainly caused by alkali-silica reactions and alkali-carbonate reactions, but a third type of deterioration involves slow/late expanding alkali-silicate/silica reactivity. The alkalies NaOH and KOH in the concrete pore solutions are mainly responsible for attack on expansive rocks and minerals in concrete. Methods for evaluating alkali-aggregate reaction potential in aggregates, and field and laboratory methods for detecting deterioration are discussed. Examples of alkali-aggregate reactions in structures is western Canada are detailed, including a water reservoir at Canadian Forces Base Chilliwack in British Columbia, the Oldman River diversion and flume, the Lundbreck Falls Bridge, and the St Mary's Reservoir spillway, all in southern Alberta. Mitigative measures include avoidance of use of suspect aggregates, but if this cannot be avoided it is recommended to keep the total alkalies in the concrete as low as possible and minimize opportunities for saturation of concrete by moisture. 16 refs., 19 figs., 1 tab

  4. The technical development on recycled aggregate concrete for nuclear facility

    International Nuclear Information System (INIS)

    Sukekiyo, M.; Saishu, S.; Ishikura, T.; Ishigure, K.

    2000-01-01

    The large amount of non-radioactive concrete waste generated by decommissioning has a very big impact on the final disposal site. Therefore, NUPEC has been developing technology which recovers at a high ratio the aggregate from the dismantling concrete with a quality which can be used to construct a new nuclear power plant. The developed high-quality recycled aggregate meets the quality standards of the natural aggregate stipulated by the Japanese architectural standard specifications for nuclear power plant facilities. As a result of these experiments, it was confirmed that the recycled concrete which used this high-quality recycled aggregate had a performance equal or better than ordinary concrete which used natural aggregate. (authors)

  5. Physio-chemical reactions in recycle aggregate concrete.

    Science.gov (United States)

    Tam, Vivian W Y; Gao, X F; Tam, C M; Ng, K M

    2009-04-30

    Concrete waste constitutes the major proportion of construction waste at about 50% of the total waste generated. An effective way to reduce concrete waste is to reuse it as recycled aggregate (RA) for the production of recycled aggregate concrete (RAC). This paper studies the physio-chemical reactions of cement paste around aggregate for normal aggregate concrete (NAC) and RAC mixed with normal mixing approach (NMA) and two-stage mixing approach (TSMA) by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Four kinds of physio-chemical reactions have been recorded from the concrete samples, including the dehydration of C(3)S(2)H(3), iron-substituted ettringite, dehydroxylation of CH and development of C(6)S(3)H at about 90 degrees C, 135 degrees C, 441 degrees C and 570 degrees C, respectively. From the DSC results, it is confirmed that the concrete samples with RA substitution have generated less amount of strength enhancement chemical products when compared to those without RA substitution. However, the results from the TSMA are found improving the RAC quality. The pre-mix procedure of the TSMA can effectively develop some strength enhancing chemical products including, C(3)S(2)H(3), ettringite, CH and C(6)S(3)H, which shows that RAC made from the TSMA can improve the hydration processes.

  6. Physio-chemical reactions in recycle aggregate concrete

    International Nuclear Information System (INIS)

    Tam, Vivian W.Y.; Gao, X.F.; Tam, C.M.; Ng, K.M.

    2009-01-01

    Concrete waste constitutes the major proportion of construction waste at about 50% of the total waste generated. An effective way to reduce concrete waste is to reuse it as recycled aggregate (RA) for the production of recycled aggregate concrete (RAC). This paper studies the physio-chemical reactions of cement paste around aggregate for normal aggregate concrete (NAC) and RAC mixed with normal mixing approach (NMA) and two-stage mixing approach (TSMA) by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Four kinds of physio-chemical reactions have been recorded from the concrete samples, including the dehydration of C 3 S 2 H 3 , iron-substituted ettringite, dehydroxylation of CH and development of C 6 S 3 H at about 90 deg. C, 135 deg. C, 441 deg. C and 570 deg. C, respectively. From the DSC results, it is confirmed that the concrete samples with RA substitution have generated less amount of strength enhancement chemical products when compared to those without RA substitution. However, the results from the TSMA are found improving the RAC quality. The pre-mix procedure of the TSMA can effectively develop some strength enhancing chemical products including, C 3 S 2 H 3 , ettringite, CH and C 6 S 3 H, which shows that RAC made from the TSMA can improve the hydration processes

  7. SHAPE ANALYSIS OF FINE AGGREGATES USED FOR CONCRETE

    Directory of Open Access Journals (Sweden)

    Huan He

    2016-12-01

    Full Text Available Fine aggregate is one of the essential components in concrete and significantly influences the material properties. As parts of natures, physical characteristics of fine aggregate are highly relevant to its behaviors in concrete. The most of previous studies are mainly focused on the physical properties of coarse aggregate due to the equipment limitations. In this paper, two typical fine aggregates, i.e. river sand and crushed rock, are selected for shape characterization. The new developed digital image analysis systems are employed as the main approaches for the purpose. Some other technical methods, e.g. sieve test, laser diffraction method are also used for the comparable references. Shape characteristics of fine aggregates with different origins but in similar size ranges are revealed by this study. Compared with coarse aggregate, fine grains of different origins generally have similar shape differences. These differences are more significant in surface texture properties, which can be easily identified by an advanced shape parameter: bluntness. The new image analysis method is then approved to be efficient for the shape characterization of fine aggregate in concrete.

  8. Effect of Elevated Temperature on the Residual Properties of Quartzite, Granite and Basalt Aggregate Concrete

    Science.gov (United States)

    Masood, A.; Shariq, M.; Alam, M. Masroor; Ahmad, T.; Beg, A.

    2018-05-01

    In the present study, experimental investigations have been carried out to determine the effect of elevated temperature on the residual properties of quartzite, granite and basalt aggregate concrete mixes. Ultrasonic pulse velocity and unstressed residual compressive strength tests on cube specimens have been conducted at ambient and after single heating-cooling cycle of elevated temperature ranging from 200 to 600 °C. The relationship between ultrasonic pulse velocity and residual compressive strength of all concrete mixes have been developed. Scanning electron microscopy was also carried out to study micro structure of quartzite, granite and basalt aggregate concrete subjected to single heating-cooling cycle of elevated temperature. The results show that the residual compressive strength of quartzite aggregate concrete has been found higher than granite and basalt aggregate concrete at ambient and at all temperatures. It has also been found that the loss of strength in concrete is due to the development of micro-cracks result in failure of cement matrix and coarse aggregate bond. Further, the basalt aggregate concrete has been observed lower strength due to low affinity with Portland cements ascribed to its ferro-magnesium rich mineral composition.

  9. Durability Indicators in High Absorption Recycled Aggregate Concrete

    Directory of Open Access Journals (Sweden)

    Luis F. Jiménez

    2015-01-01

    Full Text Available The use of recycled aggregates in structural concrete production has the inconvenience of increasing the fluid transport properties, such as porosity, sorptivity, and permeability, which reduces the resistance against penetration of environmental loads such as carbon dioxide and chloride ion. In this paper, behavior of ten concrete mixtures with different percentages of coarse aggregate replacement was studied. The recycled material was recovered by crushing of concrete rubble and had high absorption values. The results showed that it is possible to achieve good resistance to carbonation and chloride penetration with up to 50% replacement of recycled coarse aggregate for 0.5 water/cement ratio. Finally, new indexes for porosity and sorptivity were proposed to assess the quality of concrete.

  10. Comparative environmental assessment of natural and recycled aggregate concrete.

    Science.gov (United States)

    Marinković, S; Radonjanin, V; Malešev, M; Ignjatović, I

    2010-11-01

    Constant and rapid increase in construction and demolition (C&D) waste generation and consumption of natural aggregate for concrete production became one of the biggest environmental problems in the construction industry. Recycling of C&D waste represents one way to convert a waste product into a resource but the environment benefits through energy consumption, emissions and fallouts reductions are not certain. The main purpose of this study is to determine the potentials of recycled aggregate concrete (concrete made with recycled concrete aggregate) for structural applications and to compare the environmental impact of the production of two types of ready-mixed concrete: natural aggregate concrete (NAC) made entirely with river aggregate and recycled aggregate concrete (RAC) made with natural fine and recycled coarse aggregate. Based on the analysis of up-to-date experimental evidence, including own tests results, it is concluded that utilization of RAC for low-to-middle strength structural concrete and non-aggressive exposure conditions is technically feasible. The Life Cycle Assessment (LCA) is performed for raw material extraction and material production part of the concrete life cycle including transport. Assessment is based on local LCI data and on typical conditions in Serbia. Results of this specific case study show that impacts of aggregate and cement production phases are slightly larger for RAC than for NAC but the total environmental impacts depend on the natural and recycled aggregates transport distances and on transport types. Limit natural aggregate transport distances above which the environmental impacts of RAC can be equal or even lower than the impacts of NAC are calculated for the specific case study. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Influence of silica fume on mechanical and physical properties of recycled aggregate concrete

    Directory of Open Access Journals (Sweden)

    Özgür Çakır

    2015-08-01

    Full Text Available Several studies related to sustainable concrete construction have encouraged development of composite binders, involving Portland cement, industrial by-products, and concrete mixes with partial replacement of natural aggregate with recycled aggregate. In this paper, the effects of incorporating silica fume (SF in the concrete mix design to improve the quality of recycled aggregates in concrete are presented. Portland cement was replaced with SF at 0%, 5% and 10%. Specimens were manufactured by replacing natural aggregates with recycled aggregates. Two size fractions (4/12 mm and 8/22 mm as recycled aggregates were used and four series of concrete mixtures were produced. In all concrete mixtures, a constant water/binder ratio at 0.50 was used and concrete mixtures with a target initial slump of S4 class (16–21 cm were prepared. Concrete properties were evaluated by means of compressive strength, tensile splitting strength, water absorption and ultrasonic pulse velocity and it was found that, using 10% SF as a cement replacement for recycled aggregate concretes enhanced the mechanical and physical properties of concrete. At all the test ages the tensile splitting strength gain of the natural aggregate concrete mixture (NA with and without SF was higher than that of the recycled concrete mixtures. Continuous and significant improvement in the tensile splitting strength of recycled aggregate concretes incorporating SF was observed. Similar to compressive strength test results, concrete incorporating 10% SF and containing 4/12 mm fraction recycled aggregates showed better performance among recycled aggregate concretes.

  12. Applicability of recycled aggregates in concrete piles for soft soil improvement.

    Science.gov (United States)

    Medeiros-Junior, Ronaldo A; Balestra, Carlos Et; Lima, Maryangela G

    2017-01-01

    The expressive generation of construction and demolition waste is stimulating several studies for reusing this material. The improvement of soft soils by concrete compaction piles has been widely applied for 40 years in some Brazilian cities. This technique is used to improve the bearing capacity of soft soils, allowing executing shallow foundations instead of deep foundations. The compaction piles use a high volume of material. This article explored the possibility of using recycled aggregates from construction waste to replace the natural aggregates in order to improve the bearing capacity of the soft soil, regarding its compressive strength. Construction wastes from different stages of a construction were used in order to make samples of concrete with recycled aggregates. The strength of concretes with natural aggregates was compared with the strength of concretes with recycled (fine and coarse) aggregates. Results show that all samples met the minimum compressive strength specified for compaction piles used to improve the bearing capacity of soft soils. The concrete with recycled aggregate from the structural stage had even higher resistances than the concrete with natural aggregates. This behaviour was attributed to the large amount of cementitious materials in the composition of this type of concrete. It was also observed that concrete with recycled fine aggregate has a superior resistance to concrete with recycled coarse aggregate.

  13. Probabilistic Analysis of Structural Member from Recycled Aggregate Concrete

    Science.gov (United States)

    Broukalová, I.; Šeps, K.

    2017-09-01

    The paper aims at the topic of sustainable building concerning recycling of waste rubble concrete from demolition. Considering demands of maximising recycled aggregate use and minimising of cement consumption, composite from recycled concrete aggregate was proposed. The objective of the presented investigations was to verify feasibility of the recycled aggregate cement based fibre reinforced composite in a structural member. Reliability of wall from recycled aggregate fibre reinforced composite was assessed in a probabilistic analysis of a load-bearing capacity of the wall. The applicability of recycled aggregate fibre reinforced concrete in structural applications was demonstrated. The outcomes refer to issue of high scatter of material parameters of recycled aggregate concretes.

  14. Using of Porcelinite as Coarse Aggregate in Concrete

    Directory of Open Access Journals (Sweden)

    Haifa Saleh

    2015-02-01

    Full Text Available In this research the ability of using porcelinite as coarse aggregate to produce light weight concrete was investigated.  The experimental program consists of preparing and testing a mixes to investigate mechanical properties of concrete, with a total of 15 cubes (100×100×100 mm, 30 cylinders (100×200 mm. The tests include compressive strength, splitting tensile strength, fresh and hardened density of  light weight concrete for different porcelinite percentages ranged between(0% to 100% of the coarse aggregate weight. The obtained results for tested specimens were compared to control one. Test results indicated that using of porcelinite in concrete mix reduces the strength of concrete Porcelinite aggregate represents a reduction in density ranging between (10%-36% of normal weight concrete, therefore there is an advantage  using this type of light weight aggregate in this country where soil bearing capacity is low in most construction sites.

  15. Pervious concrete using fly ash aggregate as coarse aggregate-an experimental study

    Science.gov (United States)

    Dash, Subhakanta; Kar, Biswabandita; Mukherjee, Partha Sarathi

    2018-05-01

    The present study deals with the fabrication of pervious concrete from fly ash aggregates. The pervious concrete were obtained by the mixture of three different size fly ash aggregates (4.75 mm,9.5 mm,12.5 mm), Portland cement, water with little amount of sand or without sand. Admixtures like Silica fume(SF) and Super plasticizer are added to the mixture to enhance the strength of concrete. Trial being taken on preparation of Fly ash based pervious concrete (FPC) with different w/c ratio i.e. 0.30, 0.35 and 0.40 respectively. Tests such as porosity, permeability and compressive, strength are studied for this concrete material and the result concluded that the concrete when cured for 28 days its compressive strength falls in between 7.15 - 15.74 MPa and permeability 9.38 - 16.07 mm/s with porosity 27.59 - 34.05% and these are suited to be used as for use as an environment friendly concrete.

  16. Laboratory-scale sodium-carbonate aggregate concrete interactions

    International Nuclear Information System (INIS)

    Westrich, H.R.; Stockman, H.W.; Suo-Anttila, A.

    1983-09-01

    A series of laboratory-scale experiments was made at 600 0 C to identify the important heat-producing chemical reactions between sodium and carbonate aggregate concretes. Reactions between sodium and carbonate aggregate were found to be responsible for the bulk of heat production in sodium-concrete tests. Exothermic reactions were initiated at 580+-30 0 C for limestone and dolostone aggregates as well as for hydrated limestone concrete, and at 540+-10 0 C for dehydrated limestone concrete, but were ill-defined for dolostone concrete. Major reaction products included CaO, MgO, Na 2 CO 3 , Na 2 O, NaOH, and elemental carbon. Sodium hydroxide, which forms when water is released from cement phases, causes slow erosion of the concrete with little heat production. The time-temperature profiles of these experiments have been modeled with a simplified version of the SLAM computer code, which has allowed derivation of chemical reaction rate coefficients

  17. Effect of Aggregate Mineralogy and Concrete Microstructure on Thermal Expansion and Strength Properties of Concrete

    Directory of Open Access Journals (Sweden)

    Jinwoo An

    2017-12-01

    Full Text Available Aggregate type and mineralogy are critical factors that influence the engineering properties of concrete. Temperature variations result in internal volume changes could potentially cause a network of micro-cracks leading to a reduction in the concrete’s compressive strength. The study specifically studied the effect of the type and mineralogy of fine and coarse aggregates in the normal strength concrete properties. As performance measures, the coefficient of thermal expansion (CTE and compressive strength were tested with concrete specimens containing different types of fine aggregates (manufactured and natural sands and coarse aggregates (dolomite and granite. Petrographic examinations were then performed to determine the mineralogical characteristics of the aggregate and to examine the aggregate and concrete microstructure. The test results indicate the concrete CTE increases with the silicon (Si volume content in the aggregate. For the concrete specimens with higher CTE, the micro-crack density in the interfacial transition zone (ITZ tended to be higher. The width of ITZ in one of the concrete specimens with a high CTE displayed the widest core ITZ (approx. 11 µm while the concrete specimens with a low CTE showed the narrowest core ITZ (approx. 3.5 µm. This was attributed to early-age thermal cracking. Specimens with higher CTE are more susceptible to thermal stress.

  18. Carbonation Coefficients from Concrete Made with High-Absorption Limestone Aggregate

    Directory of Open Access Journals (Sweden)

    Eric I. Moreno

    2013-01-01

    Full Text Available Normal aggregates employed in concrete have absorption levels in the range of 0.2% to 4% for coarse aggregate and 0.2 to 2% for fine aggregate. However, some aggregates have absorption levels above these values. As the porosity of concrete is related to the porosity of both the cement paste and the aggregate and the carbonation rate is a function, among other things, of the porosity of the material, there is concern about the effect of this high porosity material in achieving good quality concrete from the durability point of view. Thus, the objective of this investigation was to study the carbonation rates of concrete specimens made with high-absorption limestone aggregate. Four different water/cement ratios were used, and cylindrical concrete specimens were exposed to accelerated carbonation. High porosity values were obtained for concrete specimens beyond the expected limits for durable concrete. However, carbonation coefficients related to normal quality concrete were obtained for the lowest water/cement ratio employed suggesting that durable concrete may be obtained with this material despite the high porosity.

  19. The effect of recycled concrete aggregate properties on the bond strength between RCA concrete and steel reinforcement

    International Nuclear Information System (INIS)

    Butler, L.; West, J.S.; Tighe, S.L.

    2011-01-01

    The purpose of this study was to investigate the influence that replacing natural coarse aggregate with recycled concrete aggregate (RCA) has on concrete bond strength with reinforcing steel. Two sources of RCA were used along with one natural aggregate source. Numerous aggregate properties were measured for all aggregate sources. Two types of concrete mixture proportions were developed replacing 100% of the natural aggregate with RCA. The first type maintained the same water-cement ratios while the second type was designed to achieve the same compressive strengths. Beam-end specimens were tested to determine the relative bond strength of RCA and natural aggregate concrete. On average, natural aggregate concrete specimens had bond strengths that were 9 to 19% higher than the equivalent RCA specimens. Bond strength and the aggregate crushing value seemed to correlate well for all concrete types.

  20. Increased Durability of Concrete Made with Fine Recycled Concrete Aggregates Using Superplasticizers.

    Science.gov (United States)

    Cartuxo, Francisco; de Brito, Jorge; Evangelista, Luis; Jiménez, José Ramón; Ledesma, Enrique F

    2016-02-08

    This paper evaluates the influence of two superplasticizers (SP) on the durability properties of concrete made with fine recycled concrete aggregate (FRCA). For this purpose, three families of concrete were tested: concrete without SP, concrete made with a regular superplasticizer and concrete made with a high-performance superplasticizer. Five volumetric replacement ratios of natural sand by FRCA were tested: 0%, 10%, 30%, 50% and 100%. Two natural gravels were used as coarse aggregates. All mixes had the same particle size distribution, cement content and amount of superplasticizer. The w/c ratio was calibrated to obtain similar slump. The results showed that the incorporation of FRCA increased the water absorption by immersion, the water absorption by capillary action, the carbonation depth and the chloride migration coefficient, while the use of superplasticizers highly improved these properties. The incorporation of FRCA jeopardized the SP's effectiveness. This research demonstrated that, from a durability point of view, the simultaneous incorporation of FRCA and high-performance SP is a viable sustainable solution for structural concrete production.

  1. Aggregate effects on γ-ray shielding characteristics and compressive strength on concrete

    International Nuclear Information System (INIS)

    Oh, Jeong Hwan; Choi, Soo Seok; Mun, Young Bun; Lee, Jae Hyung; Choi, Hyun Kook

    2016-01-01

    We observed the γ-ray shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of 0.371 cm-1 from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a γ-ray of "1"3"7Cs, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of 3,175 kg·m"-"3. Although the unit weight of the concrete with OSS and OSG was 3,052 kg·m"-"3, which was lower than the maximum unit weight condition by 123 kg·m"-"3, its attenuation coefficient was improved by 0.012 cm-1. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced γ-ray shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing

  2. Aggregate effects on γ-ray shielding characteristics and compressive strength on concrete

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jeong Hwan; Choi, Soo Seok [Jeju National University, Jeju (Korea, Republic of); Mun, Young Bun; Lee, Jae Hyung; Choi, Hyun Kook [Sungshin Cement Co., Ltd, Sejong (Korea, Republic of)

    2016-12-15

    We observed the γ-ray shielding characteristics and compressive strength of five types of concrete using general aggregates and high-weight aggregates. The aggregates were classified into fine aggregate and coarse aggregate according to the average size. The experimental results obtained an attenuation coefficient of 0.371 cm-1 from a concrete with the oxidizing slag sand (OSS) and oxidizing slag gravel (OSG) for a γ-ray of {sup 137}Cs, which is improved by 2% compared with a concrete with typical aggregates of sand and gravel. In the unit weight measurement, a concrete prepared by iron ore sand (IOS) and OSG had the highest value of 3,175 kg·m{sup -3}. Although the unit weight of the concrete with OSS and OSG was 3,052 kg·m{sup -3}, which was lower than the maximum unit weight condition by 123 kg·m{sup -3}, its attenuation coefficient was improved by 0.012 cm-1. The results of chemical analysis of aggregates revealed that the magnesium content in oxidizing slag was lower than that in iron ore, while the calcium content was higher. The concrete with oxidizing slag aggregates demonstrated enhanced γ-ray shielding performance due to a relatively high calcium content compared with the concrete with OSS and OSG in spite of a low unit weight. All sample concretes mixed with high-weight aggregates had higher compressive strength than the concrete with typical sand and gravel. When OSS and IOS were used, the highest compressive strength was 50.2 MPa, which was an improvement by 45% over general concrete, which was achieved after four weeks of curing.

  3. Study Concerning Characterization of Some Recycled Concrete Aggregates

    Directory of Open Access Journals (Sweden)

    Robu Ion

    2016-03-01

    Full Text Available Using recycled concrete aggregates (RCA is a matter of high priority in the construction industry worldwide. In countries like the Netherlands, Denmark, Germany, USA, Japan, France recycled concrete aggregates obtained from demolition are valorized up to 90%, mainly for road construction and less in the manufacture of new concrete.

  4. The Effects of Different Fine Recycled Concrete Aggregates on the Properties of Mortar

    Science.gov (United States)

    Fan, Cheng-Chih; Huang, Ran; Hwang, Howard; Chao, Sao-Jeng

    2015-01-01

    The practical use of recycled concrete aggregate produced by crushing concrete waste reduces the consumption of natural aggregate and the amount of concrete waste that ends up in landfills. This study investigated two methods used in the production of fine recycled concrete aggregate: (1) a method that produces fine as well as coarse aggregate, and (2) a method that produces only fine aggregate. Mortar specimens were tested using a variety of mix proportions to determine how the characteristics of fine recycled concrete aggregate affect the physical and mechanical properties of the resulting mortars. Our results demonstrate the superiority of mortar produced using aggregate produced using the second of the two methods. Nonetheless, far more energy is required to render concrete into fine aggregate than is required to produce coarse as well as fine aggregate simultaneously. Thus, the performance benefits of using only fine recycled concrete aggregate must be balanced against the increased impact on the environment.

  5. Smart aggregates: multi-functional sensors for concrete structures—a tutorial and a review

    International Nuclear Information System (INIS)

    Song Gangbing; Gu Haichang; Mo Yilung

    2008-01-01

    This paper summarizes the authors' recent pioneering research work in piezoceramic-based smart aggregates and their innovative applications in concrete civil structures. The basic operating principle of smart aggregates is first introduced. The proposed smart aggregate is formed by embedding a waterproof piezoelectric patch with lead wires into a small concrete block. The proposed smart aggregates are multi-functional and can perform three major tasks: early-age concrete strength monitoring, impact detection and structural health monitoring. The proposed smart aggregates are embedded into the desired location before the casting of the concrete structure. The concrete strength development is monitored by observing the high frequency harmonic wave response of the smart aggregate. Impact on the concrete structure is detected by observing the open-circuit voltage of the piezoceramic patch in the smart aggregate. For structural health monitoring purposes, a smart aggregate-based active sensing system is designed for the concrete structure. Wavelet packet analysis is used as a signal-processing tool to analyze the sensor signal. A damage index based on the wavelet packet analysis is used to determine the structural health status. To better describe the time-history and location information of damage, two types of damage index matrices are proposed: a sensor-history damage index matrix and an actuator–sensor damage index matrix. To demonstrate the multi-functionality of the proposed smart aggregates, different types of concrete structures have been used as test objects, including concrete bridge bent-caps, concrete cylinders and a concrete frame. Experimental results have verified the effectiveness and the multi-functionality of the proposed smart aggregates. The multi-functional smart aggregates have the potential to be applied to the comprehensive monitoring of concrete structures from their earliest stages and throughout their lifetime. (topical review)

  6. Behaviour of fibre reinforced concrete using steel slag coarse aggregate produced in Qatar

    Directory of Open Access Journals (Sweden)

    Alnahhal Wael

    2017-01-01

    Full Text Available The state of Qatar suffers from the shortage of natural resources needed for concrete production. Therefore, it is essential to investigate the feasibility of using by-product recycled materials as aggregates to maintain the concrete construction industry. Several types of recyclable materials are currently used in concrete. One of the potential resources of recycled concrete is steel slag. Knowing that Steel slag is the most significant solid waste generated by Qatar Steel Company in Qatar, replacing of natural coarse aggregate with steel slag aggregate will have a significant environmental and economic impact to the state of Qatar. This paper presents the compression and flexural test results of different concrete mixes made of steel slag coarse aggregate combined with a newly developed basalt chopped fibres. The parameters investigated included the volume fraction of the fibre used and the type of coarse aggregates (natural aggregates “Gabbro” and steel slag aggregates. Plain concrete specimens containing natural coarse aggregates and steel slag aggregates with no fibres added were also tested to serve as control. Test results showed that adding the basalt chopped fibres to the concrete mixes enhanced their flexural tensile strengths at different percentages. In addition, the compressive strength of concrete made with steel slag aggregate was higher than that made with natural gabbro aggregate. Test results clearly showed that steel slag aggregates can be used as sustainable and eco-friendly alternative materials in concrete structures.

  7. Effect of fly ash on the strength of porous concrete using recycled coarse aggregate to replace low-quality natural coarse aggregate

    Science.gov (United States)

    Arifi, Eva; Cahya, Evi Nur; Christin Remayanti, N.

    2017-09-01

    The performance of porous concrete made of recycled coarse aggregate was investigated. Fly ash was used as cement partial replacement. In this study, the strength of recycled aggregate was coMPared to low quality natural coarse aggregate which has high water absorption. Compression strength and tensile splitting strength test were conducted to evaluate the performance of porous concrete using fly ash as cement replacement. Results have shown that the utilization of recycled coarse aggregate up to 75% to replace low quality natural coarse aggregate with high water absorption increases compressive strength and splitting tensile strength of porous concrete. Using fly ash up to 25% as cement replacement improves compressive strength and splitting tensile strength of porous concrete.

  8. Lithuanian Quarry Aggregates Concrete Effects of Alkaline Corrosion Tests

    Directory of Open Access Journals (Sweden)

    Aurimas Rutkauskas

    2016-02-01

    Full Text Available Aggregate alkaline corrosion of cement in concrete is going to respond in sodium and potassium hydroxide (lye with active SiO2 found in some aggregates. During this reaction, the concrete has resulted in significant internal stresses which cause deformation of the concrete, cracking and disintegration. The reaction is slow and concrete signs of decomposition appear only after a few months or years. The study used two different aggregates quarries. Studies show that Lithuania gravel contaminated with reactive particles having amorphous silicon dioxide reacting with cement in sodium and potassium hydroxide and the resulting alkaline concrete corrosion. It was found that, according to AAR 2 large aggregates include Group II – potentially reactive because of their expansion after 14 days, higher than 0.1%.

  9. Determination of the dynamic elastic constants of recycled aggregate concrete

    Science.gov (United States)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    Nowadays, construction and demolition waste constitutes a major portion of the total solid waste production in the world. Due to both environmental and economical reasons, an increasing interest concerning the use of recycled aggregate to replace aggregate from natural sources is generated. This paper presents an investigation on the properties of recycled aggregate concrete. Concrete mixes are prepared using recycled aggregates at a substitution level between 0 and 100% of the total coarse aggregate. The influence of this replacement on strengthened concrete's properties is being investigated. The properties estimated are: density and dynamic modulus of elasticity at the age of both 7 and 28 days. Also, flexural strength of 28 days specimens is estimated. The determination of the dynamic elastic modulus was made using the ultrasonic pulse velocity method. The results reveal that the existence of recycled aggregates affects the properties of concrete negatively; however, in low levels of substitution the influence of using recycled aggregates is almost negligible. Concluding, the controlled use of recycled aggregates in concrete production may help solve a vital environmental issue apart from being a solution to the problem of inadequate concrete aggregates.

  10. The suitability of concrete using recycled aggregates (RAs) for high-performance concrete (HPC)

    OpenAIRE

    Torgal, Fernando Pacheco; Ding, Y.; Miraldo, Sérgio; Abdollahnejad, Zahra; Labrincha, J. A.

    2013-01-01

    Most studies related to concrete made with recycled aggregates (RA) use uncontaminated aggregates produced in the laboratory, revealing the potential to re-use as much as 100%. However, industrially produced RA contain a certain level of impurities that can be deleterious for Portland cement concrete, thus making it difficult for the concrete industry to use such investigations unless uncontaminated RA are used. This chapter reviews current knowledge on concrete made with RA, with a focus on ...

  11. Benefits of aggregates surface modification in concrete production

    Science.gov (United States)

    Junak, J.; Sicakova, A.

    2017-10-01

    In our study, recycled concrete aggregates (RCA), which surfaces had been modified by geopolymer material based on coal fly ash, were used to produce the concrete samples. In these samples, fraction 4/8 mm was replaced by recycled concrete aggregate with a range of 100%. To modify the surface of RCA was “Solo” and “Triple stage” modification used. On these samples real density, total water absorption and compressive strength were examined after 28, 90, 180 and 365 days of hardening. The highest compressive strength 56.8 MPa, after 365 days hardening, reached sample which had improved RCA surface by “Triple stage mixing”.

  12. Compressive behavior of steel fiber reinforced recycled aggregate concrete after exposure to elevated temperatures

    OpenAIRE

    Chen, G. M.; He, Y. H.; Yang, H.; Chen, J. F.; Guo, Y.C.

    2014-01-01

    For sustainability considerations, the use of recycled aggregate in concrete has attracted many interests in the research community. One of the main concerns for using such concrete in buildings is its spalling in fire. This may be alleviated by adding steel fibers to form steel fiber reinforced recycled aggregate concrete (SFRAC). This paper presents an experimental investigation into the compressive properties of SFRAC cylinders after exposure to elevated temperatures, including the compres...

  13. STUDY ON SILICA INFUSED RECYCLED AGGREGATE CONCRETE USING DESIGN OF EXPERIMENTS

    Directory of Open Access Journals (Sweden)

    P. M. MRUDUL

    2017-04-01

    Full Text Available Recycled Aggregate (RA generated from the construction industry is used as a material for sustainable construction. The old mortar attached to these aggregates makes it porous and are generally used for low-grade applications. However, by infusing with silica fumes, the properties of recycled aggregate concrete (RAC can be improved, as the silica fumes get infused into the pores of old mortar attached to it. In this study, the optimum percentage of recycled aggregate that can be used in fresh concrete for higher grade applications was found out. Design of experiments (DoE was used to optimize percentage of silica fumes and recycled aggregate to achieve optimum properties of concrete. Equations to predict the properties of concrete were also modelled using regression analysis.

  14. Thermochemical degradation of limestone aggregate concrete on exposure to sodium fire

    International Nuclear Information System (INIS)

    Premila, M.; Sivasubramanian, K.; Amarendra, G.; Sundar, C.S.

    2008-01-01

    Limestone aggregate concrete blocks were subjected to sodium fire conforming to a realistic scenario in order to qualify them as protective sacrificial layers over structural concrete flooring in liquid metal-cooled fast breeder reactors. Mid infrared absorption measurements were carried out on these sodium fire-exposed samples as a function of depth from the affected surface. Definite signatures of thermochemical degradation indicating dehydration and structural modification of the limestone concrete have been obtained. Control runs were carried out to delineate the thermal effects of sodium fires from that of the chemical interaction effects. Measurements on limestone aggregate samples treated with fused NaOH provided direct evidence of the exact mechanism of the sodium attack on concrete. The observed degradation effects were correlated to the mechanical strength of the concrete blocks and to the intensity of the sodium fire experienced

  15. SHAPE ANALYSIS OF FINE AGGREGATES USED FOR CONCRETE

    OpenAIRE

    HE, Huan; Courard, Luc; Pirard, Eric; Michel, Frédéric

    2016-01-01

    Fine aggregate is one of the essential components in concrete and significantly influences the material properties. As parts of natures, physical characteristics of fine aggregate are highly relevant to its behaviors in concrete. The most of previous studies are mainly focused on the physical properties of coarse aggregate due to the equipment limitations. In this paper, two typical fine aggregates, i.e. river sand and crushed rock, are selected for shape characterization. The new developed d...

  16. Technical viability of self-compacting concretes with by-products from crushed coarse aggregate production

    Directory of Open Access Journals (Sweden)

    Edgar Bacarji

    Full Text Available Abstract The main objective of this work is to present the technical viability of Self Compacting Concretes (SCC containing by-products from crushed coarse aggregate production. For this purpose, a vast characterization of these by-products was made; six mixtures of SCC were produced using two different aggregates: granite and mica schist. The binder/dry aggregate (b/agg ratio by mass was 1:3. The following properties were analyzed: compressive strength, direct tensile strength, flexural tensile strength and splitting tensile strength. Granite presented the best mechanical performance. The replacement of natural sand by granite sand generated concretes with the same level of compressive strength and caused an increase in tensile strength values. The incorporation of silica fume into concrete with granite produced an increase of 17% in compressive strength. So, the use of these by-product materials can provide a technically feasible solution that is also consistent with the aims of sustainable development and preservation of the environment.

  17. Experimental research on durability of recycled aggregate concrete under freeze- thaw cycles

    Science.gov (United States)

    Cheng, Yanqiu; Shang, Xiaoyu; Zhang, Youjia

    2017-07-01

    The freeze-thaw durability of recycled aggregate concrete has significance for the concrete buildings in the cold region. In this paper, the rapid freezing and thawing cycles experience on recycle aggregate concrete was conducted to study on the effects of recycle aggregate amount, water-binder ratio and fly ash on freeze-thaw durability of recycle aggregate concrete. The results indicates that recycle aggregate amount makes the significant influence on the freeze-thaw durability. With the increase of recycled aggregates amount, the freeze-thaw resistance for recycled aggregate concrete decreases. Recycled aggregate concrete with lower water cement ratio demonstrates better performance of freeze-thaw durability. It is advised that the amount of fly ash is less than 30% for admixture of recycled aggregates in the cold region.

  18. Mechanical Properties of Steel Fiber Reinforced all Lightweight Aggregate Concrete

    Science.gov (United States)

    Yang, Y. M.; Li, J. Y.; Zhen, Y.; Nie, Y. N.; Dong, W. L.

    2018-05-01

    In order to study the basic mechanical properties and failure characteristics of all lightweight aggregate concrete with different volume of steel fiber (0%, 1%, 2%), shale ceramsite is used as light coarse aggregate. The shale sand is made of light fine aggregate and mixed with different volume of steel fiber, and the mix proportion design of all lightweight aggregate concrete is carried out. The cubic compressive strength, axial compressive strength, flexural strength, splitting strength and modulus of elasticity of steel fiber all lightweight aggregate concrete were studied. Test results show that the incorporation of steel fiber can restrict the cracking of concrete, improve crack resistance; at the same time, it shows good plastic deformation ability and failure morphology. It lays a theoretical foundation for further research on the application of all lightweight aggregate concrete in structural systems.

  19. Utilisation of Waste Marble Dust as Fine Aggregate in Concrete

    Science.gov (United States)

    Vigneshpandian, G. V.; Aparna Shruthi, E.; Venkatasubramanian, C.; Muthu, D.

    2017-07-01

    Concrete is the important construction material and it is used in the construction industry due to its high compressive strength and its durability. Now a day’s various studies have been conducted to make concrete with waste material with the intention of reducing cost and unavailability of conventional materials. This paper investigates the strength properties of concrete specimens cast using waste marble dust as replacement of fine aggregate. The marble pieces are finely crushed to powdered and the gradation is compared with conventional fine aggregate. Concrete specimen were cast using wmd in the laboratory with different proportion (25%, 50% and 100%) by weight of cement and from the studies it reveals that addition of waste marble dust as a replacement of fine aggregate marginally improves compressive, tensile and flexural strength in concrete.

  20. Numerical Simulation of Recycled Concrete Using Convex Aggregate Model and Base Force Element Method

    Directory of Open Access Journals (Sweden)

    Yijiang Peng

    2016-01-01

    Full Text Available By using the Base Force Element Method (BFEM on potential energy principle, a new numerical concrete model, random convex aggregate model, is presented in this paper to simulate the experiment under uniaxial compression for recycled aggregate concrete (RAC which can also be referred to as recycled concrete. This model is considered as a heterogeneous composite which is composed of five mediums, including natural coarse aggregate, old mortar, new mortar, new interfacial transition zone (ITZ, and old ITZ. In order to simulate the damage processes of RAC, a curve damage model was adopted as the damage constitutive model and the strength theory of maximum tensile strain was used as the failure criterion in the BFEM on mesomechanics. The numerical results obtained in this paper which contained the uniaxial compressive strengths, size effects on strength, and damage processes of RAC are in agreement with experimental observations. The research works show that the random convex aggregate model and the BFEM with the curve damage model can be used for simulating the relationship between microstructure and mechanical properties of RAC.

  1. Evaluation of the performance of peridotite aggregates for radiation shielding concrete

    International Nuclear Information System (INIS)

    Wang, Jinjun; Li, Guofeng; Meng, Dechuan

    2014-01-01

    Highlights: • Using peridotite rich in crystal water as aggregates of radiation-shielding concrete. • Performance of peridotite concrete is simulated and compared with ordinary concrete. • Performance of concrete samples is tested. • Neutron shielding performance can be significantly enhanced by peridotite aggregates. - Abstract: Peridotite is a kind of material that is rich in crystal water. In this paper, peridotite is used as fine and coarse aggregates for radiation shielding concrete. The transmission data of different concrete thickness and different energy neutron are calculated using Monte-Carlo method. The neutron shielding performance of the peridotite concrete samples are tested using 241 Am-Be neutron source. The results show that the peridotite is an excellent neutron shielding material

  2. Research on Durability of Big Recycled Aggregate Self-Compacting Concrete Beam

    Science.gov (United States)

    Gao, Shuai; Liu, Xuliang; Li, Jing; Li, Juan; Wang, Chang; Zheng, Jinkai

    2018-03-01

    Deflection and crack width are the most important durability indexes, which play a pivotal role in the popularization and application of the Big Recycled Aggregate Self-Compacting Concrete technology. In this research, comparative study on the Big Recycled Aggregate Self-Compacting Concrete Beam and ordinary concrete beam were conducted by measuring the deflection and crack width index. The results show that both kind of concrete beams have almost equal mid-span deflection value and are slightly different in the maximum crack width. It indicates that the Big Recycled Aggregate Self-Compacting Concrete Beam will be a good substitute for ordinary concrete beam in some less critical structure projects.

  3. Durability assessment of recycled concrete aggregates for use in new concrete.

    Science.gov (United States)

    2012-06-01

    The primary goal of this research project was to investigate the long-term durability of concrete incorporating : recycled concrete aggregate (RCA) through accelerated laboratory testing. Overall it was found that modifications to : standard aggregat...

  4. Properties of concrete blocks prepared with low grade recycled aggregates.

    Science.gov (United States)

    Poon, Chi-Sun; Kou, Shi-cong; Wan, Hui-wen; Etxeberria, Miren

    2009-08-01

    Low grade recycled aggregates obtained from a construction waste sorting facility were tested to assess the feasibility of using these in the production of concrete blocks. The characteristics of the sorted construction waste are significantly different from that of crushed concrete rubbles that are mostly derived from demolition waste streams. This is due to the presence of higher percentages of non-concrete components (e.g. >10% soil, brick, tiles etc.) in the sorted construction waste. In the study reported in this paper, three series of concrete block mixtures were prepared by using the low grade recycled aggregates to replace (i) natural coarse granite (10mm), and (ii) 0, 25, 50, 75 and 100% replacement levels of crushed stone fine (crushed natural granite concrete blocks. Test results on properties such as density, compressive strength, transverse strength and drying shrinkage as well as strength reduction after exposure to 800 degrees C are presented below. The results show that the soil content in the recycled fine aggregate was an important factor in affecting the properties of the blocks produced and the mechanical strength deceased with increasing low grade recycled fine aggregate content. But the higher soil content in the recycled aggregates reduced the reduction of compressive strength of the blocks after exposure to high temperature due probably to the formation of a new crystalline phase. The results show that the low grade recycled aggregates obtained from the construction waste sorting facility has potential to be used as aggregates for making non-structural pre-cast concrete blocks.

  5. Sustainable normal and high strength recycled aggregate concretes using crushed tested cylinders as coarse aggregates

    Directory of Open Access Journals (Sweden)

    Bilal S. Hamad

    2017-12-01

    Full Text Available The paper reports on a research program that was designed at the American University of Beirut (AUB to investigate the fresh and hardened mechanical properties of a high performance concrete mix produced with partial or full substitution of crushed natural lime-stone aggregates with recycled aggregates from crushed tested cylinders in batching plants. Choosing crushed cylinders as source of recycling would result in reusing portion of the waste products of the concrete production industry. An extensive concrete batching and testing program was conducted to achieve two optimum normal and high strength concrete mixes. The variables were the nominal concrete strength (28 or 60 MPa and the percentage replacement of natural coarse aggregates with recycled aggregates from crushed tested cylinders (0, 20, 40, 60, 80, or 100%. Normal strength tested cylinders were used as source of the recycled aggregates for the normal strength concrete (NSC mix and high strength tested cylinders were used for the high strength concrete (HSC mix. Tests on the trial batches included plastic state slump and hardened state mechanical properties including cylinder compressive strength, cylinder splitting tensile strength, modulus of elasticity, and standard beams flexural strength. The results indicated no significant effect on the slump and around 10% average reduction in the hardened mechanical properties for both investigated levels of concrete compressive strength.

  6. Mechanical and Physical Properties of Polyester Polymer Concrete Using Recycled Aggregates from Concrete Sleepers

    Directory of Open Access Journals (Sweden)

    Francisco Carrión

    2014-01-01

    Full Text Available Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate, and waste aggregates (basalt and limestone coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%, and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior.

  7. Mechanical and physical properties of polyester polymer concrete using recycled aggregates from concrete sleepers.

    Science.gov (United States)

    Carrión, Francisco; Montalbán, Laura; Real, Julia I; Real, Teresa

    2014-01-01

    Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate), and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption) was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%), and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior.

  8. Chemical-mineralogical characterisation of coarse recycled concrete aggregate

    International Nuclear Information System (INIS)

    Limbachiya, M.C.; Marrocchino, E.; Koulouris, A.

    2007-01-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO 2 , Al 2 O 3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO 2 and increase in Al 2 O 3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition

  9. Chemical-mineralogical characterisation of coarse recycled concrete aggregate.

    Science.gov (United States)

    Limbachiya, M C; Marrocchino, E; Koulouris, A

    2007-01-01

    The construction industry is now putting greater emphasis than ever before on increasing recycling and promoting more sustainable waste management practices. In keeping with this approach, many sectors of the industry have actively sought to encourage the use of recycled concrete aggregate (RCA) as an alternative to primary aggregates in concrete production. The results of a laboratory experimental programme aimed at establishing chemical and mineralogical characteristics of coarse RCA and its likely influence on concrete performance are reported in this paper. Commercially produced coarse RCA and natural aggregates (16-4 mm size fraction) were tested. Results of X-ray fluorescence (XRF) analyses showed that original source of RCA had a negligible effect on the major elements and a comparable chemical composition between recycled and natural aggregates. X-ray diffraction (XRD) analyses results indicated the presence of calcite, portlandite and minor peaks of muscovite/illite in recycled aggregates, although they were directly proportioned to their original composition. The influence of 30%, 50%, and 100% coarse RCA on the chemical composition of equal design strength concrete has been established, and its suitability for use in a concrete application has been assessed. In this work, coarse RCA was used as a direct replacement for natural gravel in concrete production. Test results indicated that up to 30% coarse RCA had no effect on the main three oxides (SiO2, Al2O3 and CaO) of concrete, but thereafter there was a marginal decrease in SiO2 and increase in Al2O3 and CaO contents with increase in RCA content in the mix, reflecting the original constituent's composition.

  10. Effects of Uncrushed Aggregate on the Mechanical Properties of No-Fines Concrete

    Directory of Open Access Journals (Sweden)

    M. A. Memon

    2018-06-01

    Full Text Available Concrete’s self-weight is a major aspect of a structure’s overall weight. Recently, the use of lightweight concrete (no-fines, foamed and cellular concrete has been increased. Normally no-fines concrete is produced with crushed coarse aggregate of uniform gradation. This study aims to investigate experimentally the effects of the use of uncrushed coarse aggregates on unit weight, compressive and tensile strength of the no-fines (NFC as well as conventional concrete (CC. In addition, the effects of coarse aggregate size on the mechanical properties were also studied. Four gradations of uncrushed coarse aggregates ranging between (5.5-4.75 mm, (10-4.75 mm, (20-4.75 mm and (25-4.75 mm were used for preparing the concretes. The fixed cement-aggregate ratios of 1:6 (with w/c ratio=0.4 and 1:2:4 (with w/c ratio=0.5 were adopted for NFC and CC respectively. It was found that the gradation of uncrushed coarse aggregate has a significant effect on the mechanical properties of NFC. A maximum of 16% reduction in self-weight of the concrete without fines was obtained, as compared to that with fines. Moreover, the compressive strength of no-fines concrete significantly improved by replacing crushed with uncrushed coarse aggregate. The compressive strength increased by 16% for the batch of (25-4.75 mm.

  11. Comparison of different forms of gravel as aggregate in concrete

    Directory of Open Access Journals (Sweden)

    Sikiru ORITOLA

    2014-11-01

    Full Text Available Gradation plays an important role in the workability, segregation, and pump ability of concrete. Uniformly distributed aggregates require less paste which will also decrease bleeding, creep and shrinkage while producing better workability, more durable concrete and higher packing. This attempt looks at the effect of particle size distribution pattern for five types of gravel aggregate forms, angular, elongated, smooth rounded, irregular and flaky as related to the strength of concrete produced. Different forms of naturally existing gravel aggregate were collected from a particular location and tests were carried out on them to determine their gradation. Based on the gradation the aggregates were used to prepare different samples of grade 20 concrete with water-cement ratio of 0.5. The particle size distribution resulted in coefficients of uniformity ranging from 1.24 to 1.44. The granite aggregate, which serves as a reference, had a coefficient of uniformity of 1.47. Tests were conducted on fresh and hardened concrete cube samples. The concrete sample CT5 recorded a slump of 32mm and highest compressive strength value of 21.7 N/mm2, among the concrete produced from different forms of gravel.

  12. Compressive strength performance of OPS lightweight aggregate concrete containing coal bottom ash as partial fine aggregate replacement

    Science.gov (United States)

    Muthusamy, K.; Mohamad Hafizuddin, R.; Mat Yahaya, F.; Sulaiman, M. A.; Syed Mohsin, S. M.; Tukimat, N. N.; Omar, R.; Chin, S. C.

    2018-04-01

    Concerns regarding the negative impact towards environment due to the increasing use of natural sand in construction industry and dumping of industrial solid wastes namely coal bottom ash (CBA) and oil palm shell (OPS) has resulted in the development of environmental friendly lightweight concrete. The present study investigates the effect of coal bottom ash as partial fine aggregate replacement towards workability and compressive strength of oil palm shell lightweight aggregate concrete (OPS LWAC). The fresh and mechanical properties of this concrete containing various percentage of coal bottom ash as partial fine aggregate replacement were investigated. The result was compared to OPS LWAC with 100 % sand as a control specimen. The concrete workability investigated by conducting slump test. All specimens were cast in form of cubes and water cured until the testing age. The compressive strength test was carried out at 7 and 28 days. The finding shows that integration of coal bottom ash at suitable proportion enhances the strength of oil palm shell lightweight aggregate concrete.

  13. Laboratory evaluation of recycled concrete as aggregate in new concrete pavements.

    Science.gov (United States)

    2014-09-01

    The Washington State Department of Transportation (WSDOT) has initiated a research project to investigate the use of recycled concrete as : aggregates (RCA) in Portland (hydraulic) cement concrete pavements (PCCP). The planned source for the RCA in t...

  14. Enhancement of properties of recycled coarse aggregate concrete using bacteria

    Science.gov (United States)

    Sahoo; Arakha; Sarkar; P; Jha

    2016-01-01

    Due to rapid construction, necessity for raw materials of concrete, especially coarse aggregate, tends to increase the danger of early exhaustion of the natural resources. An alternative source of raw materials would perhaps delay the advent of this early exhaustion. Recycled coarse aggregate (RCA) plays a great role as an alternative raw material that can replace the natural coarse aggregate (NCA) for concrete. Previous studies show that the properties of RCA concrete are inferior in quality compared to NCA concrete. This article attempts to study the improvement of properties of RCA concrete with the addition of bacteria named as Bacillus subtilis. The experimental investigation was carried out to evaluate the improvement of the compressive strength, capillary water absorption, and drying shrinkage of RCA concrete incorporating bacteria. The compressive strength of RCA concrete is found to be increased by about 20% when the cell concentration of B. subtilis is 106 cells/ml. The capillary water absorption as well as drying shrinkage of RCA are reduced when bacteria is incorporated. The improvement of RCA concrete is confirmed to be due to the calcium carbonate precipitation as observed from the microstructure studies carried out on it such as EDX, SEM, and XRD.

  15. Influence of silica fume on mechanical and physical properties of recycled aggregate concrete

    OpenAIRE

    Çakır, Özgür; Sofyanlı, Ömer Özkan

    2015-01-01

    Several studies related to sustainable concrete construction have encouraged development of composite binders, involving Portland cement, industrial by-products, and concrete mixes with partial replacement of natural aggregate with recycled aggregate. In this paper, the effects of incorporating silica fume (SF) in the concrete mix design to improve the quality of recycled aggregates in concrete are presented. Portland cement was replaced with SF at 0%, 5% and 10%. Specimens were manufactured ...

  16. Blasted copper slag as fine aggregate in Portland cement concrete.

    Science.gov (United States)

    Dos Anjos, M A G; Sales, A T C; Andrade, N

    2017-07-01

    The present work focuses on assessing the viability of applying blasted copper slag, produced during abrasive blasting, as fine aggregate for Portland cement concrete manufacturing, resulting in an alternative and safe disposal method. Leaching assays showed no toxicity for this material. Concrete mixtures were produced, with high aggregate replacement ratios, varying from 0% to 100%. Axial compressive strength, diametrical compressive strength, elastic modulus, physical indexes and durability were evaluated. Assays showed a significant improvement in workability, with the increase in substitution of fine aggregate. With 80% of replacement, the concrete presented lower levels of water absorption capacity. Axial compressive strength and diametrical compressive strength decreased, with the increase of residue replacement content. The greatest reductions of compressive strength were found when the replacement was over 40%. For tensile strength by diametrical compression, the greatest reduction occurred for the concrete with 80% of replacement. After the accelerated aging, results of mechanic properties showed a small reduction of the concrete with blasted copper slag performance, when compared with the reference mixture. Results indicated that the blasted copper slag is a technically viable material for application as fine aggregate for concrete mixtures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Fundamental Study on the Development of Structural Lightweight Concrete by Using Normal Coarse Aggregate and Foaming Agent

    Science.gov (United States)

    Lee, Han-Seung; Ismail, Mohamed A.; Woo, Young-Je; Min, Tae-Beom; Choi, Hyun-Kook

    2014-01-01

    Structural lightweight concrete (SLWC) has superior properties that allow the optimization of super tall structure systems for the process of design. Because of the limited supply of lightweight aggregates in Korea, the development of structural lightweight concrete without lightweight aggregates is needed. The physical and mechanical properties of specimens that were cast using normal coarse aggregates and different mixing ratios of foaming agent to evaluate the possibility of creating structural lightweight concrete were investigated. The results show that the density of SLWC decreases as the dosage of foaming agent increases up to a dosage of 0.6%, as observed by SEM. It was also observed that the foaming agent induced well separated pores, and that the size of the pores ranged from 50 to 100 μm. Based on the porosity of concrete specimens with foaming agent, compressive strength values of structural lightweight foam concrete (SLWFC) were obtained. It was also found that the estimated values from proposed equations for compressive strength and modulus of elasticity of SLWFC, and values obtained by actual measurements were in good agreement. Thus, this study confirms that new structural lightweight concrete using normal coarse aggregates and foaming agent can be developed successfully. PMID:28788691

  18. Influence of recycled aggregate quality and proportioning criteria on recycled concrete properties.

    Science.gov (United States)

    López-Gayarre, F; Serna, P; Domingo-Cabo, A; Serrano-López, M A; López-Colina, C

    2009-12-01

    This paper presents the results of experimental research using concrete produced by substituting part of the natural coarse aggregates with recycled aggregates from concrete demolition. The influence of the quality of the recycled aggregate (amount of declassified and source of aggregate), the percentage of replacement on the targeted quality of the concrete to be produced (strength and workability) has been evaluated. The granular structure of concrete and replacement criteria were analyzed in this study, factors which have not been analyzed in other studies. The following properties of recycled concretes were analyzed: density, absorption, compressive strength, elastic modulus, amount of occluded air, penetration of water under pressure and splitting tensile strength. A simplified test program was designed to control the costs of the testing while still producing sufficient data to develop reliable conclusions in order to make the number of tests viable whilst guaranteeing the reliability of the conclusions. Several factors were analyzed including the type of aggregate, the percentage of replacement, the type of sieve curve, the declassified content, the strength of concrete and workability of concrete and the replacement criteria. The type of aggregate and the percentage of replacement were the only factors that showed a clear influence on most of the properties. Compressive strength is clearly affected by the quality of recycled aggregates. If the water-cement ratio is kept constant and the loss of workability due to the effect of using recycled aggregate is compensated for with additives, the percentage of replacement of the recycled aggregate will not affect the compressive strength. The elastic modulus is affected by the percentage of replacement. If the percentage of replacement does not exceed 50%, the elastic modulus will only change slightly.

  19. FEATURES OF ASH OF THERMAL POWER PLANTS AS AGGREGATE FOR CONCRETES

    Directory of Open Access Journals (Sweden)

    M. A. Storozhuk

    2017-10-01

    Full Text Available Purpose. The scientific work is dedicated to development of scientific-technical bases of production and application of concrete on the basis of ashes of thermal power plants (TPP. Methodology. The properties of TPP ash, as well as the peculiarities of its behavior in a concrete mix as a fine aggregate, have been studied. It is shown that the hydrolysis and hydration of cement occur in the active environment of ash, which has a huge specific surface area. This significantly affects the course of these processes and the quality of the concrete produced. A new technology of application of ash of TPP for preparation of concrete mixes is offered. Vibrated and vibrovacuumized concretes of optimum composition from slag and ash, as well as from granite crushed stone and ash, are tested. The chara-cteristics of ordinary concrete (from granite crushed stone and quartz sand are given to compare. Findings. The results of the tests showed the possibility of obtaining concretes of class C20/25…C25/30 on the basis of slag and ash of TPP at a limited consumption of cement. It is shown that the concrete with traditional aggregates has a lower strength than the concrete, which has ash as fine aggregate. This research results contribute to the increased use of ash in construction that solves the problem of aggregates as well as thermal power plants waste recycling. Originality. New method and technology of application of TPP ashes in concrete are developed. Ash concrete mix has rational flowability, which produces the greatest strength of ash vacuum concrete. This strength is twice or more as large as the strength of vibrated ash concrete mix with flowability S1. Practical value. The physico-chemical properties of TPP ash as aggregate for concrete are presented. Significant difference of ash from ordinary aggregates is shown. Chemical activity of the ash is justified. The special conditions of cement hardening in the case of using ash as aggregate for concrete

  20. Recycled tires as coarse aggregate in concrete pavement mixtures.

    Science.gov (United States)

    2013-07-01

    The reuse potential of tire chips as coarse aggregates in pavement concrete was examined in this research by : investigating the effects of low- and high-volume tire chips on fresh and hardened concrete properties. One concrete : control mixture was ...

  1. TOPICAL REVIEW: Smart aggregates: multi-functional sensors for concrete structures—a tutorial and a review

    Science.gov (United States)

    Song, Gangbing; Gu, Haichang; Mo, Yi-Lung

    2008-06-01

    This paper summarizes the authors' recent pioneering research work in piezoceramic-based smart aggregates and their innovative applications in concrete civil structures. The basic operating principle of smart aggregates is first introduced. The proposed smart aggregate is formed by embedding a waterproof piezoelectric patch with lead wires into a small concrete block. The proposed smart aggregates are multi-functional and can perform three major tasks: early-age concrete strength monitoring, impact detection and structural health monitoring. The proposed smart aggregates are embedded into the desired location before the casting of the concrete structure. The concrete strength development is monitored by observing the high frequency harmonic wave response of the smart aggregate. Impact on the concrete structure is detected by observing the open-circuit voltage of the piezoceramic patch in the smart aggregate. For structural health monitoring purposes, a smart aggregate-based active sensing system is designed for the concrete structure. Wavelet packet analysis is used as a signal-processing tool to analyze the sensor signal. A damage index based on the wavelet packet analysis is used to determine the structural health status. To better describe the time-history and location information of damage, two types of damage index matrices are proposed: a sensor-history damage index matrix and an actuator-sensor damage index matrix. To demonstrate the multi-functionality of the proposed smart aggregates, different types of concrete structures have been used as test objects, including concrete bridge bent-caps, concrete cylinders and a concrete frame. Experimental results have verified the effectiveness and the multi-functionality of the proposed smart aggregates. The multi-functional smart aggregates have the potential to be applied to the comprehensive monitoring of concrete structures from their earliest stages and throughout their lifetime.

  2. Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture.

    Science.gov (United States)

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia Mª; Guerra-Romero, M Ignacio

    2014-09-01

    The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique.

  3. Strength development of concrete made with recycled glass aggregates subjected to frost curing conditions

    OpenAIRE

    Poutos, Konstantinos; Nwaubani, Sunny

    2013-01-01

    An experimental investigation was undertaken to study whether the strength behavior of concrete made with glass aggregate differed significantly from that made with natural aggregates when concretes cured in low temperatures. The aim of the research work presented is to examine the strength behavior of glass concrete when cured under freezing conditions at -15°C and -10°C. The results showed that when glass concrete is cured at low curing temperature, the 28 day compressive strength is higher...

  4. Concrete manufactured with crushed asphalt as partial replacement of natural aggregates

    Directory of Open Access Journals (Sweden)

    L. Coppola

    2016-09-01

    Full Text Available The paper focuses on the reuse of crushed asphalt (GA as a partial replacement (up to 20% of natural aggregates for concrete manufacture. Addition of GA aggregates produced a positive effect on workability loss. The GA mixes, however, showed a significant tendency to bleed and segregate at the highest replacement percentage applied. GA led to a decrease of compressive strength in concrete (with respect to that of the reference concrete up to 50% due to the weakness of the cement paste / recycled aggregate interface. To compensate for this negative effect, a reduction of w/c for the GA concretes was necessary. A decrease of w/c allowed the GA concretes to show drying shrinkage values substantially similar to those of reference concrete with the same cement factor. The experimental results confirmed the possibility of partial substitution (max. 15% of natural aggregates with crushed asphalt for making concrete.

  5. Physico-mechanical properties of high performance concrete using different aggregates in presence of silica fume

    Directory of Open Access Journals (Sweden)

    Salah A. Abo-El-Enein

    2014-04-01

    Full Text Available Heavy weight high performance concrete (HPC can be used when particular properties, such as high strength and good radiation shielding are required. Such concrete, using ilmenite and hematite coarse aggregates can significantly have higher specific gravities than those of concrete made with dolomite and air-cooled slag aggregates. Four different concrete mixes with the same cement content and different w/c ratios were designed using normal dolomite aggregate, air-cooled slag by-product and two different types of iron ore aggregates. High performance concrete (grade-M60 can be achieved using superplasticizer to reduce the water/cement ratio; the effect of SF on the performance of concrete was studied by addition of 10% silica fume to the total cement content. The physico-mechanical properties of coarse aggregates and hardened concrete were studied. The results show that, Ilmenite coarse aggregate gives higher physical and mechanical properties than the other aggregates. Also, addition of 10% silica fume developed a stronger and a denser interfacial transition zone (ITZ between concrete particles and the cement matrix. Crushed air-cooled slag can be used to produce a high-strength concrete with better mechanical properties than corresponding concrete made with crushed hematite and ilmenite. Heavy density concrete made with fine aggregates of ilmenite and air-cooled slag are expected to be suitable as shielding materials to attenuate gamma rays.

  6. Flexural Behavior of Corroded Reinforced Recycled Aggregate Concrete Beams

    Directory of Open Access Journals (Sweden)

    Taoping Ye

    2018-01-01

    Full Text Available Recycling concrete not only reduces the use of virgin aggregate but also decreases the pressure on landfills. As a result, recycled coarse aggregate (RCA is extensively recommended for new construction projects. However, the flexural behavior of corroded reinforced recycled aggregate concrete (RAC beams is uncertain. The experimental research presented in this paper was performed to investigate the flexural behavior of corroded reinforced RAC beams compared to that of corroded reinforced natural aggregate concrete (NAC beams and consequently explore the possibility of using RAC beams in corrosive environments. Four different percentages of RCA in total mass of coarse aggregate in concrete mixtures (0%, 33%, 66%, and 100% and two different concrete strengths (C30, C60 were the governing parameters. The electrochemical method was adopted to accelerate steel corrosion. Full-scale tests were performed on eight simply supported beams until the failure load was reached. Comparison of load-deflection behavior, crack patterns, failure modes, ductility, and ultimate flexural capacity of corroded reinforced NAC and RAC beams was made based on the experimental results obtained. The comparison results show that the flexural behavior of corroded reinforced RAC beams with an appropriate percentage of RCA is satisfactory compared to the behavior of NAC beams.

  7. Recovery of MSWI and soil washing residues as concrete aggregates.

    Science.gov (United States)

    Sorlini, Sabrina; Abbà, Alessandro; Collivignarelli, Carlo

    2011-02-01

    The aim of the present work was to study if municipal solid waste incinerator (MSWI) residues and aggregates derived from contaminated soil washing could be used as alternative aggregates for concrete production. Initially, chemical, physical and geometric characteristics (according to UNI EN 12620) of municipal solid waste incineration bottom ashes and some contaminated soils were evaluated; moreover, the pollutants release was evaluated by means of leaching tests. The results showed that the reuse of pre-treated MSWI bottom ash and washed soil is possible, either from technical or environmental point of view, while it is not possible for the raw wastes. Then, the natural aggregate was partially and totally replaced with these recycled aggregates for the production of concrete mixtures that were characterized by conventional mechanical and leaching tests. Good results were obtained using the same dosage of a high resistance cement (42.5R calcareous Portland cement instead of 32.5R); the concrete mixture containing 400 kg/m(3) of washed bottom ash and high resistance cement was classified as structural concrete (C25/30 class). Regarding the pollutants leaching, all concrete mixtures respected the limit values according to the Italian regulation. Copyright © 2010 Elsevier Ltd. All rights reserved.

  8. Structural recycled concrete: utilization of recycled aggregate from construction and demolition wastes

    International Nuclear Information System (INIS)

    Alaejos Gutierrez, P.; Sanchez de Juan, M.

    2015-01-01

    This paper aims to present the main results of CEDEX research works concerning the use of recycled aggregates for structural concretes. By way of conclusion, recommendations on the requirements of the recycled aggregates have been established, providing information about the influence of these aggregates on the properties of structural concrete. (Author)

  9. Applicability assessment of concrete with recycled coarse aggregates in Havana, Cuba

    OpenAIRE

    Pavón, E.; Etxeberria, M.; Díaz, N. E.

    2012-01-01

    The recent viability studies carried out in Havana, Cuba, according to natural or recycled aggregates, exhibited high volume production of construction and demolition waste (CDW). The last well-known data of concrete waste generation reached to 1800 m3/month. This situation, together with the depletion of the quarry aggregates closed to the capital, requires the use of such debris as aggregate for concrete production. In this work, four origin recycled concrete aggregates (RCA) were produced ...

  10. Use of recycled fine aggregate in concretes with durable requirements.

    Science.gov (United States)

    Zega, Claudio Javier; Di Maio, Angel Antonio

    2011-11-01

    The use of construction waste materials as aggregates for concrete production is highly attractive compared to the use of non-renewable natural resources, promoting environmental protection and allowing the development of a new raw material. Several countries have recommendations for the use of recycled coarse aggregate in structural concrete, whereas the use of the fine fraction is limited because it may produce significant changes in some properties of concrete. However, during the last decade the use of recycled fine aggregates (RFA) has achieved a great international interest, mainly because of economic implications related to the shortage of natural sands suitable for the production of concrete, besides to allow an integral use of this type of waste. In this study, the durable behaviour of structural concretes made with different percentage of RFA (0%, 20%, and 30%) is evaluated. Different properties related to the durability of concretes such as absorption, sorptivity, water penetration under pressure, and carbonation are determined. In addition, the results of compressive strength, static modulus of elasticity and drying shrinkage are presented. The obtained results indicate that the recycled concretes have a suitable resistant and durable behaviour, according to the limits indicated by different international codes for structural concrete. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. ASSESSMENT OF THE ASR EXPANSION OF CONCRETE MADE WITH RECYCLED CONCRETE AGGREGATES

    OpenAIRE

    Boehme, Luc; Joseph, Miquel

    2016-01-01

    The amount of construction and demolition waste is increasing all over the world. Most of this waste consists of concrete and masonry. These waste materials are very suitable to be recycled. After carrying out an advanced recycling procedure, it’s possible to produce highquality recycled aggregates. Until now, most of these aggregates are used in low grade application as in road foundations. In Flanders, where the market in road works is now almost saturated, using more recycled concrete aggr...

  12. Mechanical and Physical Properties of Hydrophobized Lightweight Aggregate Concrete with Sewage Sludge.

    Science.gov (United States)

    Suchorab, Zbigniew; Barnat-Hunek, Danuta; Franus, Małgorzata; Łagód, Grzegorz

    2016-04-27

    This article is focused on lightweight aggregate-concrete modified by municipal sewage sludge and lightweight aggregate-concrete obtained from light aggregates. The article presents laboratory examinations of material physical parameters. Water absorptivity of the examined material was decreased by the admixture of water emulsion of reactive polysiloxanes. Water transport properties were determined using Time Domain Reflectometry, an indirect technique for moisture detection in porous media. Together with basic physical parameters, the heat conductivity coefficient λ was determined for both types of lightweight aggregate-concrete. Analysis of moisture and heat properties of the examined materials confirmed the usefulness of light aggregates supplemented with sewage sludge for prospective production.

  13. Preplaced aggregate concrete application on Fort St. Vrain PCRV construction

    International Nuclear Information System (INIS)

    Ople, F.S. Jr.

    1976-01-01

    Two distinct concreting methods were employed in the construction of the prestressed concrete reactor vessel (PCRV) of the Fort St. Vrain (FSV) Nuclear Generating Station, a 330 MW(e) High Temperature Gas-Cooled Reactor installation near Denver, Colorado. Preplaced aggregate concrete (PAC) techniques were employed in the PCRV bottom head and the core support floor; conventional job-mixed concrete was used in the PCRV sidewall and top head regions. This paper describes the successful application of PAC techniques utilized primarily in solving construction difficulties associated with confined and heavily congested regions of the PCRV. The PAC technique consists of placing coarse aggregate inside the forms, followed by injection of grout under pressure through embedded pipes to fill the interstices in the aggregate mass. Details of the PAC construction method including grout mix development, grouting equipment, grout pipe layout, grouting sequence, grout level monitoring, concrete temperature control, and pre-construction mockups are described. (author)

  14. Durability of recycled aggregate concrete using pozzolanic materials.

    Science.gov (United States)

    Ann, K Y; Moon, H Y; Kim, Y B; Ryou, J

    2008-01-01

    In this study, pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS) were used to compensate for the loss of strength and durability of concrete containing recycled aggregate. As a result, 30% PFA and 65% GGBS concretes increased the compressive strength to the level of control specimens cast with natural granite gravel, but the tensile strength was still lowered at 28 days. Replacement with PFA and GGBS was effective in raising the resistance to chloride ion penetrability into the concrete body, measured by a rapid chloride ion penetration test based on ASTM C 1202-91. It was found that the corrosion rate of 30% PFA and 65% GGBS concretes was kept at a lower level after corrosion initiation, compared to the control specimens, presumably due to the restriction of oxygen and water access. However, it was less effective in increasing the chloride threshold level for steel corrosion. Hence, it is expected that the corrosion time for 30% PFA and 65% GGBS concrete containing recycled aggregate mostly equates to the corrosion-free life of control specimens.

  15. Influence of Waste Brick Powder in the Mechanical Properties of Recycled Aggregate Concrete

    Directory of Open Access Journals (Sweden)

    Viviana Letelier

    2018-03-01

    Full Text Available Brick and concrete are the main materials contributing to demolition and construction waste. Considering this precedent, the effects of using both residuals in medium strength concretes are analyzed. Waste brick powder is used as a cement replacement in three different levels: 5%, 10%, and 15%, and it is tested in concretes with no recycled aggregates and concretes with 30% of recycled coarse aggregates replacing natural ones. The compressive strength, the flexural strength, and modulus of elasticity are calculated and compared to a control concrete with no brick powder and no recycled aggregates. The effects of the simultaneous use of both residuals on the physical properties of the recycled concrete are highlighted. Results show that 15% of cement can be replaced by waste brick powder together with 30% of recycled aggregates without suffering significant losses in the strength of the final material when compared to a control concrete.

  16. Lightweight concrete with Algerian limestone dust: Part I: Study on 30% replacement to normal aggregate at early age

    Directory of Open Access Journals (Sweden)

    S. Kitouni

    2013-12-01

    Full Text Available The mechanical characteristics of the lightweight aggregate concretes (LWAC strongly depend on the proportions of aggregates in the formulation. In particular, because of their strong porosity, the lightweight aggregates are much more deformable than the cementations matrix and their influence on concrete strength is complex. This paper focuses on studying the physical performance of concrete formulated with substitution of 30% of coarse aggregates by limestone dust. In this article an attempt is made to provide information on the elastic properties of lightweight concrete (LWC from tests carried out under uniaxial compression conditions. The results of Young modulus, Poisson's ratio, and compressive and flexural tensile strength tests on concrete are presented. The concretes obtained present good mechanical performances reaching 34.99 MPa compressive strength, 6.39 MPa flexural tensile strength and in front of 36 MPa Young modulus.

  17. Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

    Directory of Open Access Journals (Sweden)

    al-Swaidani Aref M.

    2015-11-01

    Full Text Available The objective of this paper is to report a part of an ongoing research on the influence of using crushed basalt as aggregates on one of durability-related properties of concrete (i.e. alkali-silica reaction which is the most common form of Alkali-Aggregate Reaction. Alkali resistance has been assessed through several methods specified in the American Standards. Results of petrographic examination, chemical test (ASTM C289 and accelerated mortar bar test (ASTM C1260 have particularly been reported. In addition, the weight change and compressive strength of 28 days cured concrete containing basaltic aggregates were also reported after 90 days of exposure to 10% NaOH solution. Dolomite aggregate were used in the latter test for comparison. The experimental results revealed that basaltic rocks quarried from As-Swaida’a region were suitable for production of aggregates for concrete. According to the test results, the studied basalt aggregates can be classified as innocuous with regard to alkali-silica reaction. Further, the 10% sodium hydroxide attack did not affect the compressive strength of concrete.

  18. Early age shrinkage pattern of concrete on replacement of fine aggregate with industrial by-product

    Directory of Open Access Journals (Sweden)

    R.K. Mishra

    2016-10-01

    Full Text Available This is an experimental work carried out to investigate early age shrinkage pattern of concrete, prepared, on 50% replacement of industrial by-product (like pond ash and granulated blast furnace slag as fine aggregate using OPC, PPC and PSC as a binder. This is to observe the effect of pond ash and slag as they are having some cementitious properties and effect of cement type is also discussed. All the mixes were prepared keeping in view of pumpable concrete without any super plasticizers. Higher shrinkage value indicates the presence of more bleed water or internal moisture. It is concluded that slag is the best option for fine aggregate replacement for concrete making and durable structure.

  19. Very early age concrete hydration characterization monitoring using piezoceramic based smart aggregates

    International Nuclear Information System (INIS)

    Kong, Qingzhao; Song, Gangbing; Hou, Shuang; Ji, Qing; Mo, Y L

    2013-01-01

    Very early age (0–20 h) concrete hydration is a complicated chemical reaction. During the very early age period, the concrete condition dramatically changes from liquid state to solid state. This paper presents the authors’ recent research on monitoring very early age concrete hydration characterization by using piezoceramic based smart aggregates. The smart aggregate (SA) transducer is designed as a sandwich structure using two marble blocks and a pre-soldered lead zirconate titanate (PZT) patch. Based on the electromechanical property of piezo materials, the PZT patches function as both actuators and sensors. In addition, the marble blocks provide reliable protection to the fragile PZT patch and develop the SA into a robust embedded actuator or sensor in the structure. The active-sensing approach, which involved a pair of smart aggregates with one as an actuator and the other one as a sensor, was applied in this paper’s experimental investigation of concrete hydration characterization monitoring. In order to completely understand the hydration condition of the inhomogeneous, over-cluttering, high-scattering characteristics of concrete (specifically of very early concrete), a swept sine wave and several constant frequency sine waves were chosen and produced by a function generator to excite the embedded actuating smart aggregate. The PZT vibration induced ultrasonic wave propagated through the concrete and was sent to the other smart aggregate sensor. The electrical signal transferred from the smart aggregate sensor was recorded during the test. As the concrete hydration reaction was occurring, the characteristic of the electrical signal continuously changed. This paper describes the successful investigation of the three states (the fluid state, the transition state, and the hardened state) of very early age concrete hydration based on classification of the received electrical signal. Specifically, the amplitude and frequency response of the electrical

  20. Estimating the shear strength of concrete with coarse aggregate replacement

    OpenAIRE

    Folagbade Olusoga Peter ORIOLA; George MOSES; Jacob Oyeniyi AFOLAYAN; John Engbonye SANI

    2017-01-01

    For economic, environmental and practical reasons, it is desirable to replace the constituents of concrete with wastes and cheaper alternative materials. However, it is best when such replacements are done at optimum replacement levels. In view of this, a laboratory investigative test was carried out to evaluate the shear strength of concrete with coarse aggregate replacement by Coconut Shell and by Waste Rubber Tyre. The coarse aggregate replacement was done at recommended optimum proportion...

  1. Pre-Saturation Technique of the Recycled Aggregates: Solution to the Water Absorption Drawback in the Recycled Concrete Manufacture †

    Science.gov (United States)

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-del Pozo, Julia Mª; Guerra-Romero, M. Ignacio

    2014-01-01

    The replacement of natural aggregates by recycled aggregates in the concrete manufacturing has been spreading worldwide as a recycling method to counteract the large amount of construction and demolition waste. Although legislation in this field is still not well developed, many investigations demonstrate the possibilities of success of this trend given that concrete with satisfactory mechanical and durability properties could be achieved. However, recycled aggregates present a low quality compared to natural aggregates, the water absorption being their main drawback. When used untreated in concrete mix, the recycled aggregate absorb part of the water initially calculated for the cement hydration, which will adversely affect some characteristics of the recycled concrete. This article seeks to demonstrate that the technique of pre-saturation is able to solve the aforementioned problem. In order to do so, the water absorption of the aggregates was tested to determine the necessary period of soaking to bring the recycled aggregates into a state of suitable humidity for their incorporation into the mixture. Moreover, several concrete mixes were made with different replacement percentages of natural aggregate and various periods of pre-saturation. The consistency and compressive strength of the concrete mixes were tested to verify the feasibility of the proposed technique. PMID:28788188

  2. Assessment of aggregates- cement paste border in concretes containing silica fume and fly ash

    Directory of Open Access Journals (Sweden)

    Ali Sademomtazi

    2017-12-01

    Full Text Available The bond between aggregate and cement paste, called the interfacial transition zone (ITZ is an important parameter that effect on the mechanical properties and durability of concrete. Transition zone microstructure and porosity (pores of cement paste or concrete are affected by the type and properties of materials used which evaluated in this research. On the other hand, the use of efficient, low-cost and reliable method is particularly important for evaluating of concrete performance against the chloride ion penetration and its relationships with transition zone as a suitable index to assess the durability. So far, various methods to approach the electrical Indices are presented. In this research, the effect of pozzolanic materials fly ash (10%, 20% and 30% and silica fume (5% and 10% as substitute of cement by weight in binary and ternary mixtures on the fresh and hardened concrete properties were investigated. To determine mechanical properties, the compressive strength, splitting tensile strength and modulus of elasticity tests were performed. Also, water penetration depth, porosity, water sorptivity, specific electrical resistivity, rapid chloride penetration test (RCPT and rapid chloride migration test (RCMT tests were applied to evaluate concrete durability. To examine the border of aggregate and cement paste morphology of concrete specimens, scanning electron microscope images (SEM was used. The fresh concrete results showed that the presence of silica fume in binary and ternary mixtures reduced workability and air content but fly ash increased them. Adding silica fume to mixtures of containing flay ash while increasing mechanical strength reduced the porosity and pores to 18%. The presence of pozzolanic materials in addition to increasing bond quality and uniformity of aggregate-cement matrix border a considerably positive effect on the transport properties of concrete.

  3. Acoustic emission monitoring of recycled aggregate concrete under bending

    Science.gov (United States)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.

  4. The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths.

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

    2014-12-08

    In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete's compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength.

  5. Aggregate Toughness/Abrasion Resistance and Durability/Soundness Tests Related to Asphalt Concrete Performance in Pavements

    Science.gov (United States)

    1998-03-01

    The properties of aggregates used in asphalt concretes are very important to the performance of the pavements in which the asphalt concretes are used. Often pavement distress, such as stripping and rutting, can be traced directly to the aggregates us...

  6. Microstructure and mechanical properties of recycled aggregate concrete in seawater environment.

    Science.gov (United States)

    Yue, Pengjun; Tan, Zhuoying; Guo, Zhiying

    2013-01-01

    This study aims to conduct research about the microstructure and basic properties of recycled aggregate concrete under seawater corrosion. Concrete specimens were fabricated and tested with different replacement percentages of 0%, 30%, and 60% after immersing in seawater for 4, 8, 12, and 16 months, respectively. The basic properties of recycled aggregate concrete (RAC) including the compressive strength, the elastic modulus, and chloride penetration depth were explicitly investigated. And the microstructure of recycled concrete aggregate (RCA) was revealed to find the seawater corrosion by using scanning electron microscope (SEM). The results showed that higher amount of the RCA means more porosity and less strength, which could lower both the compressive strength and resistance to chloride penetration. This research could be a guide in theoretical and numerical analysis for the design of RAC structures.

  7. Mechanical and Physical Properties of Polyester Polymer Concrete Using Recycled Aggregates from Concrete Sleepers

    OpenAIRE

    Carrión, F.; Montalban Domingo, Maria Laura; Real Herráiz, Julia Irene; Real, T.

    2014-01-01

    Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate) and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strenght, flexural strength, modulus of elasticity,...

  8. Investigations on Fresh and Hardened Properties of Recycled Aggregate Self Compacting Concrete

    Science.gov (United States)

    Revathi, P.; Selvi, R. S.; Velin, S. S.

    2013-09-01

    In the recent years, construction and demolition waste management issues have attracted the attention from researchers around the world. In the present study, the potential usage of recycled aggregate obtained from crushed demolition waste for making self compacting concrete (SCC) was researched. The barriers in promoting the use of recycled material in new construction are also discussed. In addition, the results of an experimental study involving the use of recycled concrete aggregate as coarse aggregates for producing self-compacting concrete to study their flow and strength characteristics are also presented. Five series of mixture were prepared with 0, 25, 50, 75, and 100 % coarse recycled aggregate adopting Nan Su's mix proportioning method. The fresh concrete properties were evaluated through the slump flow, J-ring and V-funnel tests. Compressive and tensile strengths were also determined. The results obtained showed that SCC could be successfully developed by incorporating recycled aggregates.

  9. FRP-Confined Recycled Coarse Aggregate Concrete: Experimental Investigation and Model Comparison

    Directory of Open Access Journals (Sweden)

    Yingwu Zhou

    2016-10-01

    Full Text Available The in situ application of recycled aggregate concrete (RAC is of great significance in environmental protection and construction resources sustainability. However, it has been limited to nonstructural purposes due to its poor mechanical performance. External confinement using steel tubes and fiber-reinforced polymer (FRP can significantly improve the mechanical performance of RAC and thus the first-ever study on the axial compressive behavior of glass FRP (GFRP-confined RAC was recently reported. To have a full understanding of FRP-confined RAC, this paper has extended the type of FRP and presents a systematic experimental study on the axial compressive performance of carbon FRP (CFRP-confined RAC. The mechanical properties of CFRP-confined RAC from the perspective of the failure mode, ultimate strength and strain, and stress–strain relationship responses were analyzed. Integrated with existing experimental data of FRP-confined RAC, the paper compiles a database for the mechanical properties of FRP-confined RAC. Based on the database, the effects of FRP type (i.e., GFRP and CFRP and the replacement ratio of recycled coarse aggregate were investigated. The results indicated that the stress–stain behavior of FRP-confined RAC depended heavily on the unconfined concrete strength and the FRP confining pressure instead of the replacement ratio. Therefore, this study adopted eleven high-performance ultimate strength and strain models developed for FRP-confined normal aggregate concrete (NAC to predict the mechanical properties of FRP-confined RAC. All the predictions had good agreement with the test results, which further confirmed similar roles played by FRP confinement in improving the mechanical properties of RAC and improving those of NAC. On this basis, this paper finally recommended a stress–strain relationship model for FRP-confined RAC.

  10. Properties of concrete containing different type of waste materials as aggregate replacement exposed to elevated temperature – A review

    Science.gov (United States)

    Ghadzali, N. S.; Ibrahim, M. H. W.; Sani, M. S. H. Mohd; Jamaludin, N.; Desa, M. S. M.; Misri, Z.

    2018-04-01

    Concrete is the chief material of construction and it is non-combustible in nature. However, the exposure to the high temperature such as fire can lead to change in the concrete properties. Due to the higher temperature, several changes in terms of mechanical properties were observed in concrete such as compressive strength, modulus of elasticity, tensile strength and durability of concrete will decrease significantly at high temperature. The exceptional fire-proof achievement of concrete is might be due to the constituent materials of concrete such as its aggregates. The extensive use of aggregate in concrete will leads to depletion of natural resources. Hence, the use of waste and other recycled and by-product material as aggregates replacements becomes a leading research. This review has been made on the utilization of waste materials in concrete and critically evaluates its effects on the concrete performances during the fire exposure. Therefore, the objective of this paper is to review the previous search work regarding the concrete containing waste material as aggregates replacement when exposed to elevated temperature and come up with different design recommendations to improve the fire resistance of structures.

  11. Measurement of γ-Ray Attenuation Coefficient for Concrete with Different Aggregate

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Jeong Hwan [Jeju National University, Jeju (Korea, Republic of); Lee, Jea Hyung; Mun, Young Bum; Choi, Hyun Kook [Sungshin Cement Co, Sejong (Korea, Republic of); Choi, Soo Seok [Jeju National University, Jeju (Korea, Republic of)

    2016-05-15

    In this work, we used different aggregates in a concrete to examine their effect on gamma-ray shielding. In addition, attenuation coefficient has been evaluated using a gamma-ray measuring system. The attenuation coefficient represents the amount of attenuated radiation by the thickness of a given sample material. Shielding performance improvement is expected to effect on the increasing high-weight aggregate rather than unit weigh and it is consider that additional research is needed for mixing condition of aggregates. In this study, shielding performance of concrete was confirmed to increase, according to the increasing in unit weight and aggregate. However, Iron ore is the density greater than oxidizing slag gravel, but attenuation coefficient is lower than including oxidizing slag gravel. The demand of radiation shielding material for a safe transport and storage of radioactive materials increases rapidly with the commencement of the medium and low-level radioactive waste disposal facility. It is because radioactive materials from a nuclear reactor, spent nuclear fuels, fission products, and many industrial application of radiation influences on environment over a long period by releasing gamma-ray and neutron continuously. Typical radiation shielding materials are lead, boron, iron, water, heavy-weight concrete, etc. In heavy-weight concrete, oxidizing slag from an electric arc furnace, magnetite and barite are used as an aggregate. The radiation shielding rate of the heavy-weight concrete which used oxidizing slag was studied. Both size of coarse aggregate and experiment sample is a few cm thicknesses. Therefore, location of shielding material including metal component in sample is important, according to direction of radiation.

  12. The Fire Resistance Performance of Recycled Aggregate Concrete Columns with Different Concrete Compressive Strengths

    Science.gov (United States)

    Dong, Hongying; Cao, Wanlin; Bian, Jianhui; Zhang, Jianwei

    2014-01-01

    In order to ascertain the fire resistance performance of recycled aggregate concrete (RAC) components with different concrete compressive strengths, four full-scaled concrete columns were designed and tested under high temperature. Two of the four specimens were constructed by normal concrete with compressive strength ratings of C20 and C30, respectively, while the others were made from recycled coarse aggregate (RCA) concrete of C30 and C40, respectively. Identical constant axial forces were applied to specimens while being subjected to simulated building fire conditions in a laboratory furnace. Several parameters from the experimental results were comparatively analyzed, including the temperature change, vertical displacement, lateral deflection, fire endurance, and failure characteristics of specimens. The temperature field of specimens was simulated with ABAQUS Software (ABAQUS Inc., Provindence, RI, USA) and the results agreed quite well with those from the experiments. Results show that the rate of heat transfer from the surface to the interior of the column increases with the increase of the concrete’s compressive strength for both RAC columns and normal concrete columns. Under the same initial axial force ratio, for columns with the same cross section, those with lower concrete compressive strengths demonstrate better fire resistance performance. The fire resistance performance of RAC columns is better than that of normal concrete columns, with the same concrete compressive strength. PMID:28788279

  13. Engineering Behavior of Concrete with Recycled Aggregate

    Directory of Open Access Journals (Sweden)

    Ayob Afizah

    2017-01-01

    Full Text Available Concrete is extensively used as construction materials in Malaysia. Concrete contributes suitable feature for construction industry for instance durability, adequate compressive strength, fire resistance, availability and is economic as compared to other construction materials. Depletion of natural resources and disposal of construction and demolition waste remarkably claim environmental threat. In this paper, the engineering behavior, durability, and concrete microstructure of recycled concrete aggregates (RCA on short-term concrete properties were investigated. The studied concrete at design mix proportion of 1:0.55:2.14:2.61 (weight of cement :coarse aggregates :sand :water used to obtain medium-high compressive strength with 20%, 50%, and 100% of RCA. Results show that for the same water/cement ratio, RCA replacement up to 50% still achieved the targeted compressive strength of 25 MPa at 28 curing days. Addition, at similar RCA replacement, the highest carbonation depth value was found at 1.03 mm which could be attributed to the pozzolanic reaction, thus led to lower carbonation resistance. Scanning electron microscopy microstructure shows that the RCA surface was porous and covered with loose particles. Moreover, the interfacial transition zone was composed of numerous small pores, micro cracks, and fissures that surround the mortar matrix. On the basis of the obtained results, recommendable mineral admixtures of RCA are necessary to enhance the quality of concrete construction.

  14. Evaluation of Colemanite Waste as Aggregate Hot Mix Asphalt Concrete

    Directory of Open Access Journals (Sweden)

    Nihat MOROVA

    2015-09-01

    Full Text Available In this study usability of waste colemanite which is obtained after cutting block colemanite for giving proper shape to blocks as an aggregate in hot mix asphalt. For this aim asphalt concrete samples were prepared with four different aggregate groups and optimum bitumen content was determined. First of all only limestone was used as an aggregate. After that, only colemanite aggregate was used with same aggregate gradation. Then, the next step of the study, Marshall samples were produced by changing coarse and fine aggregate gradation as limestone and colemanite and Marshall test were conducted. When evaluated the results samples which produced with only limestone aggregate gave the maximum Marshall Stability value. When handled other mixture groups (Only colemanite, colemanite as coarse aggregate-limestone as fine aggregate, colemanite as fine aggregate-limestone as coarse aggregate all groups were verified specification limits. As a result, especially in areas where there is widespread colemanite waste, if transportation costs did not exceed the cost of limestone, colemanite stone waste could be used instead of limestone in asphalt concrete mixtures as fine aggregate

  15. The alkali–aggregate reaction for various aggregates used in concrete

    Directory of Open Access Journals (Sweden)

    Calderón, V.

    2010-09-01

    Full Text Available The aim of this work is to contribute to the knowledge of the interactions between aggregates and the components of the interstitial phase of concrete and to determine whether those aggregates that are subsequently used in the manufacture of concrete are reagents and are therefore likely to undergo a progressive deterioration of their initial properties. An initial petrographic study of each aggregate is performed in order to be able to determine its subsequent behaviour and reactivity under the influence of various factors. The potential reactivity of different silicaceous aggregates (slates, gneiss, hornfels, granites, quartzite and serpentine is then determined by a chemical method for evaluating the potential reactivity of aggregates and an accelerated method in mortar specimens, and finally the surface reactivity is investigated. The results of these studies suggest that some aggregates are able to react with the components of the interstitial phase of concrete. The existence of this kind of interaction is confirmed by the results of the surface investigations before and after the basic reaction.

    Este trabajo pretende contribuir al conocimiento de las reacciones de interacción entre los áridos y los componentes de la fase intersticial del hormigón y determinar si estos áridos, empleados posteriormente en la fabricación del hormigón, son reactivos y por tanto susceptibles de provocar una disminución progresiva de sus propiedades iniciales. Para la caracterización de cada árido se ha realizado un estudio petrográfico, fundamental a la hora de determinar su posterior comportamiento en términos de reactividad frente a diversos factores. Seguidamente, se ha analizado la reactividad potencial de diferentes áridos silicatados (pizarras, gneis, corneanas, granitos, cuarcita y serpentina mediante los dos métodos normalizados existentes: el método químico para la determinación de la reactividad potencial de áridos y

  16. Mix design and properties of fly ash waste lightweight aggregates in structural lightweight concrete

    Directory of Open Access Journals (Sweden)

    Manu S. Nadesan

    2017-12-01

    Full Text Available Concrete is one of the most widely used construction materials and has the ability to consume industrial wastes in high volume. As the demand for concrete is increasing, one of the effective ways to reduce the undesirable environmental impact of the concrete is by the use of waste and by-product materials as cement and aggregate substitutes in concrete. One such waste material is fly ash, which is produced in large quantities from thermal power plants as a by-product. A substantial amount of fly ash is left unused posing environmental and storage problems. The production of sintered lightweight aggregate with fly ash is an effective method to dispose of fly ash in large quantities. Due to lack of a proper mix design procedure, the production and application of lightweight aggregate in structural concrete are not much entertained. The absorption characteristic of lightweight aggregate is a major concern, while developing the mix proportioning of lightweight concretes. The present study is an attempt to establish a new mix design procedure for the development of sintered fly ash lightweight aggregate concretes, which is simple and more reliable than the existing procedures. Also, the proposed methodology has been validated by developing a spectrum of concretes having water cement ratios varying from 0.25 to 0.75. From the study, it is obvious that the development of 70 MPa concrete is possible by using cement alone without any additives. Also, it is ensured that all the concretes have densities less than 2000 kg/m3.

  17. Compressive Strength of Concrete made from Natural Fine Aggregate Sources in Minna, Nigeria

    Directory of Open Access Journals (Sweden)

    M. Abdullahi

    2017-12-01

    Full Text Available This work presented an investigation of concrete developed from five fine aggregate sources in Minna, Niger state, Nigeria. Tests conducted on the fine aggregate samples included specific gravity, sieve analysis, bulk density and moisture content. The concrete mix design was done using absolute volume method at various mix proportion of 1:2:4, 1:2:3 and 1:1:2 and water-cement ratios of 0.4, 0.45, 0.5, 0.55 and 0.6. The compressive strengths of concrete were determined at 28-day curing age. Test results revealed that the specific gravities of the aggregate were between 2.60 to 2.70, compacted bulk densities also ranged from 1505.18 to 1701.15kg/m3, loose bulk densities ranged from 1379.32 to 1478.17kg/m3, and moisture content ranged from 0.93 to 2.47%. All the fine aggregate samples satisfied the overall and medium grading limits for natural fine aggregates. The coarse aggregate used fairly followed the grading limit for aggregate size of 20 to 5 mm. The compressive strength of the concrete obtained using the aggregate samples A, B, C, D, and Eall within the ranges of 18.97 to 34.98 N/mm2. Statistical models were developed for the compressive strength of concrete as a function of water-cement ratio for various fine aggregate sources and mix proportions. The models were found to have good predictive the capabilities of the compressive strength of concrete for given water-cement ratio. The properties of fine aggregates and the resulting concrete characteristics showed that all the fine aggregate samples are suitable to be used for concrete production.

  18. Evaluation of recycled concrete aggregates for their suitability in construction activities: An experimental study.

    Science.gov (United States)

    Puthussery, Joseph V; Kumar, Rakesh; Garg, Anurag

    2017-02-01

    Construction and demolition waste disposal is a major challenge in developing nations due to its ever increasing quantities. In this study, the recycling potential of waste concrete as aggregates in construction activities was studied. The metal leaching from the recycled concrete aggregates (RCA) collected from the demolition site of a 50year old building, was evaluated by performing three different leaching tests (compliance, availability and Toxic Characteristic Leaching Procedure). The metal leaching was found mostly within the permissible limit except for Hg. Several tests were performed to determine the physical and mechanical properties of the fine and coarse aggregates produced from recycled concrete. The properties of recycled aggregates were found to be satisfactory for their utilization in road construction activities. The suitability of using recycled fine and coarse aggregates with Portland pozzolanic cement to make a sustainable and environmental friendly concrete mix design was also analyzed. No significant difference was observed in the compressive strength of various concrete mixes prepared by natural and recycled aggregates. However, only the tensile strength of the mix prepared with 25% recycled fine aggregates was comparable to that of the control concrete. For other mixes, the tensile strength of the concrete was found to drop significantly. In summary, RCA should be considered seriously as a building material for road construction, mass concrete works, lightly reinforced sections, etc. The present work will be useful for the waste managers and policy makers particularly in developing nations where proper guidelines are still lacking. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Lattice modeling of aggregate interlocking in concrete

    DEFF Research Database (Denmark)

    Eliáš, Jan; Stang, Henrik

    2012-01-01

    roughness, i.e.what is termed aggregate interlocking. We demonstrate this enhancement via the simulation of mixed-mode experiments on concrete performed at a laboratory at the Technical University of Denmark. Double notched concrete specimens were initially pre-cracked in tension. Then, various combinations...

  20. Shape characterization of concrete aggregate

    NARCIS (Netherlands)

    Stroeven, P.; Hu, J.

    2006-01-01

    As a composite material, the performance of concrete materials can be expected to depend on the properties of the interfaces between its two major components, aggregate and cement paste. The microstructure at the interfacial transition zone (ITZ) is assumed to be different from the bulk material. In

  1. Effect of Stress Amplitude on the Damping of Recycled Aggregate Concrete.

    Science.gov (United States)

    Liang, Chaofeng; Liu, Tiejun; Xiao, Jianzhuang; Zou, Dujian; Yang, Qiuwei

    2015-08-14

    Damping characterizes the energy dissipation capacity of materials and structures, and it is affected by several external factors such as vibrating frequency, stress history, temperature, and stress amplitude. This study investigates the relationship between the damping and the stress amplitude of environment-friendly recycled aggregate concrete (RAC). First, a function model of a member's loss factor and stress amplitude was derived based on Lazan's damping-stress function. Then, the influence of stress amplitude on the loss tangent of RAC was experimentally investigated. Finally, parameters used to determine the newly derived function were obtained by numerical fitting. It is shown that the member's loss factor is affected not only by the stress amplitude but also by factors such as the cross section shapes, boundary conditions, load types, and loading positions. The loss tangent of RAC increases with the stress amplitude, even at low stress amplitude. The damping energy exponent of RAC is not identically equal to 2.0, indicating that the damping is nonlinear. It is also found that the energy dissipation capacity of RAC is superior to that of natural aggregate concrete (NAC), and the energy dissipation capacity can be further improved by adding modified admixtures.

  2. Characterization of concrete made with recycled aggregate from concrete demolition waste

    Directory of Open Access Journals (Sweden)

    Terán Gilmore, A.

    2007-12-01

    Full Text Available The present study aimed: to characterize the physical, chemical and mechanical properties of recycled aggregate from construction and concrete structure demolition waste, processed before and after crushing; to characterize fresh and hardened concrete made with such recycled aggregate; and to design different doses varying the water/cement ratio, the amount of cement and the use of superplasticizing admixtures to offset the effects of absorption. The ultimate objective was to provide a broader perspective of the use of recycled aggregate in the manufacture of new concrete.El presente estudio nos permite caracterizar las propiedades físicas, químicas y mecánicas de los áridos reciclados, producto de residuos de la construcción y demolición de estructuras de hormigón, tratándolos antes y después de triturar; caracterizar el hormigón elaborado con áridos reciclados, en su estado fresco y endurecido, diseñando diferentes dosificaciones variando la relación agua/cemento, la cantidad de cemento y el uso de aditivos súper plastificantes para disminuir el efecto de la absorción; caracterización que nos permite tener una mayor perspectiva sobre el uso de áridos reciclados en la elaboración de nuevos hormigones.

  3. Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst.

    Science.gov (United States)

    Gurdián, Hebé; García-Alcocel, Eva; Baeza-Brotons, Francisco; Garcés, Pedro; Zornoza, Emilio

    2014-04-21

    The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash) and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes.

  4. Carbonation around near aggregate regions of old hardened concrete cement paste

    International Nuclear Information System (INIS)

    Tam, Vivian W.Y.; Gao, X.F.; Tam, C.M.

    2005-01-01

    Analogous with most modern cities, waste disposal is a pressing issue due to limited landfill and public filling (land reclamation) areas in Hong Kong in which construction and demolition (C and D) waste forms the major source. Concrete, apportioning the largest portion of C and D waste, has the greatest potential for recycling. However, the knowledge on micro-structural behavior of concrete waste is immature to give adequate details on the macro-behavior of concrete waste. This paper attempts to examine the problems of recycling old concrete by investigating the microstructure and phase transformation of the concrete samples collected from buildings with 46 and 37 years of services. From the results of Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) examination, it is found that there are a lot of pores at the near layers of aggregate where carbonation of the hardened cement paste (HCP) is high. The pores may be generated as a result of poor workmanship such as insufficient concrete mixing time, trapping of air voids beneath coarse aggregate, inappropriate water to cement ratio, and the microclimate conditions such as humidity that affects the demand on water from the aggregate during mixing

  5. Impact of crushed mineral aggregate on the pumpability of concrete during transport and placement

    Directory of Open Access Journals (Sweden)

    Topličić-Ćurčić Gordana

    2016-01-01

    Full Text Available In the spirit of the sustainable buildings, and with the goal of protection of river courses, in the near future an already announced directive ordering closing down of a large number of river aggregate dredging operations will be adopted. For that reason, usage of crushed mineral aggregate in concrete mixes is increasing. Irrespective of downsides of the fined crushed mineral aggregate, such as the presence of fine particles bordering the upper permissible limit and the unfavorable shape of the grain of the course aggregate for obtaining liquid consistency required for the pumpable concrete, the demanded pumpability of concrete during transport and placement has been achieved. By adding admixtures to concrete, the required concrete properties, such as: frost resistance, simultaneous frost and salt resistance and water tightness have been achieved. [Projekat Ministarstva nauke Republike Srbije, br. TR 36017: Utilization of by - products and recycled waste materials in concrete composites in the scope of sustainable construction development in Serbia: investigation and environmental assessment of possible applications

  6. Mechanical Properties of Lightweight Concrete Using Recycled Cement-Sand Brick as Coarse Aggregates Replacement

    Science.gov (United States)

    Joohari, Ilya; Farhani Ishak, Nor; Amin, Norliyati Mohd

    2018-03-01

    This paper presents the result of replacing natural course aggregate with recycled cement-sand brick (CSB) towards the mechanical properties of concrete. Natural aggregates were used in this study as a control sample to compare with recycled coarse aggregates. This study was also carried to determine the optimum proportion of coarse aggregates replacement to produce lightweight concrete. Besides, this study was conducted to observe the crack and its behaviour development during the mechanical testing. Through this study, four types of concrete mixed were prepared, which were the control sample, 25%, 50% and 75% replacement of CSB. The test conducted to determine the effectiveness of recycled CSB as coarse aggregates replacement in this study were slump test, density measurement, compression test, and flexural test and. The strength of concrete was tested at 7 days and 28 days of curing. From the results obtained, the optimum proportion which produced the highest strength is 25% replacement of recycled CSB. The compressive and flexural strength has decreased by 10%-12% and 4%-34% respectively compared to the control sample. The presence of recycled coarse aggregates in sample has decreased the density of concrete by 0.8%-3% compared to the control sample.

  7. Influence of bagasse ash and recycled concrete aggregate on hardened properties of high-strength concrete

    Directory of Open Access Journals (Sweden)

    P. Rattanachu

    2018-04-01

    Full Text Available This research aimed to use of bagasse ash as a cement replacement in high-strength recycled aggregate concrete (HS-RAC. Crushed limestone was replaced with 100% recycled concrete aggregate (RCA and the ground bagasse ash (GBA was used to partially replace ordinary Portland cement (OPC at 20, 35 and 50%wt of binder to cast HS-RAC. The results indicated that the replacing of crushed limestone with RCA had a negative impact on the properties of the concrete. Increasing the amount of GBA in HS-RAC resulted in a decrease in density and an increase in the volume of permeable pore space. The concrete mixtures prepared with 20%wt GBA replacement of OPC promoted greater the compressive strength than the conventional concrete (CT concrete at 90 days or more. HS-RAC with GBA (up to 50% was more durable in terms of chloride ion penetration resistance, although it had lower compressive strength than the CT concrete.

  8. Study on Effects of Different Replacement Rate on Bending Behavior of Big Recycled Aggregate Self Compacting Concrete

    Science.gov (United States)

    Li, Jing; Guo, Tiantian; Gao, Shuai; Jiang, Lin; Zhao, Zhijun; Wang, Yalin

    2018-03-01

    Big recycled aggregate self compacting concrete is a new type of recycled concrete, which has the advantages of low hydration heat and green environmental protection, but its bending behavior can be affected by different replacement rate. Therefor, in this paper, the research status of big Recycled aggregate self compacting concrete was systematically introduced, and the effect of different replacement rate of big recycled aggregate on failure mode, crack distribution and bending strength of the beam were studied through the bending behavior test of 4 big recycled aggregate self compacting concrete beams. The results show that: The crack distribution of the beam can be affected by the replacement rate; The failure modes of big recycled aggregate beams are the same as those of ordinary concrete; The plane section assumption is applicable to the big recycled aggregate self compacting concrete beam; The higher the replacement rate, the lower the bending strength of big recycled aggregate self compacting concrete beams.

  9. Utilisation of iron ore tailings as aggregates in concrete

    OpenAIRE

    Francis Atta Kuranchie; Sanjay Kumar Shukla; Daryoush Habibi; Alireza Mohyeddin

    2015-01-01

    Sustainable handling of iron ore tailings is of prime concern to all stakeholders who are into iron ore mining. This study seeks to add value to the tailings by utilising them as a replacement for aggregates in concrete. A concrete mix of grade 40 MPa was prepared in the laboratory with water–cement ratio of 0.5. The concrete were cured for 1, 2, 3, 7, 14 and 28 days. The properties of the concrete such as workability, durability, density, compressive strength and indirect tensile strength we...

  10. The influence of aggregates type on W/C ratio on the strength and other properties of concrete

    Science.gov (United States)

    Malaiskiene, J.; Skripkiunas, G.; Vaiciene, M.; Karpova, E.

    2017-10-01

    The influence of different types of aggregates and W/C ratio on concrete properties is analysed. In order to achieve this aim, lightweight (with expanded clay aggregate) and normal concrete (with gravel aggregate) mixtures are prepared with different W/C ratios. Different W/C ratios are selected by reducing the amount of cement when the amount of water is constant. The following properties of concrete have been determined: density, compressive strength and water absorption. Additionally, the statistical data analysis is performed and influence of aggregate type and W/C ratio on concrete properties is determined. The empirical equations indicating dependence between concrete strength and W/C and strength of aggregate are obtained for normal concrete and light-weight concrete.

  11. The durability of concrete containing recycled tyres as a partial replacement of fine aggregate

    Science.gov (United States)

    Syamir Senin, Mohamad; Shahidan, Shahiron; Syazani Leman, Alif; Othman, Nurulain; Shamsuddin, Shamrul-mar; Ibrahim, M. H. W.; Zuki, S. S. Mohd

    2017-11-01

    Nowadays, uncontrolled disposal of waste materials such as tyres can affect the environment. Therefore, careful management of waste disposal must be done in order to conserve the environment. Waste tyres can be use as a replacement for both fine aggregate and coarse aggregate in the production of concrete. This research was conducted to assess the durability of concrete containing recycled tyres which have been crushed into fine fragments to replace fine aggregate in the concrete mix. This study presents an overview of the use of waste rubber as a partial replacement of natural fine aggregate in a concrete mix. 36 concrete cubes measuring 100mm × 100mm × 100mm and 12 concrete cubes measuring 150mm × 150mm × 150mm were prepared and added with different percentages of rubber from recycled tyres (0%, 3%, 5% and 7%) as fine aggregate replacement. The results obtained show that the replacement of fine aggregate with 7% of rubber recorded a compressive strength of 43.7MPa while the addition of 3% of rubber in the concrete sample recorded a high compressive strength of 50.8MPa. This shows that there is a decrease in the strength and workability of concrete as the amount of rubber used a replacement for fine aggregate in concrete increases. On the other hand, the water absorption test indicated that concrete which contains rubber has better water absorption ability. In this study, 3% of rubber was found to be the optimal percentage as a partial replacement for fine aggregate in the production of concrete.

  12. Optimization and influence of parameter affecting the compressive strength of geopolymer concrete containing recycled concrete aggregate: using full factorial design approach

    Science.gov (United States)

    Krishnan, Thulasirajan; Purushothaman, Revathi

    2017-07-01

    There are several parameters that influence the properties of geopolymer concrete, which contains recycled concrete aggregate as the coarse aggregate. In the present study, the vital parameters affecting the compressive strength of geopolymer concrete containing recycled concrete aggregate are analyzedby varying four parameters with two levels using full factorial design in statistical software Minitab® 17. The objective of the present work is to gain an idea on the optimization, main parameter effects, their interactions and the predicted response of the model generated using factorial design. The parameters such as molarity of sodium hydroxide (8M and 12M), curing time (6hrs and 24 hrs), curing temperature (60°C and 90°C) and percentage of recycled concrete aggregate (0% and 100%) are considered. The results show that the curing time, molarity of sodium hydroxide and curing temperature were the orderly significant parameters and the percentage of Recycled concrete aggregate (RCA) was statistically insignificant in the production of geopolymer concrete. Thus, it may be noticeable that the RCA content had negligible effect on the compressive strength of geopolymer concrete. The expected responses from the generated model showed a satisfactory and rational agreement to the experimental data with the R2 value of 97.70%. Thus, geopolymer concrete comprising recycled concrete aggregate can solve the major social and environmental concerns such as the depletion of the naturally available aggregate sources and disposal of construction and demolition waste into the landfill.

  13. COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway

    Science.gov (United States)

    Cepuritis, Rolands; Willy Danielsen, Svein

    2014-05-01

    COIN Project: Towards a zero-waste technology for concrete aggregate production in Norway Rolands Cepuritis, Norcem/NTNU and Svein Willy Danielsen, SINTEF Aggregate production is a mining operation where no purification of the "ore" is necessary. Still it is extremely rare that an aggregate production plant is operating on the basis of zero-waste concept. This is since historically the fine crushed aggregate (particles with a size of less than 2, 4 or sometimes 8 mm) has been regarded as a by-product or waste of the more valuable coarse aggregate production. The reason is that the crushed coarse aggregates can easily replace coarse rounded natural stones in almost any concrete composition; while, the situation with the sand is different. The production of coarse aggregate normally yields fine fractions with rough surface texture, flaky or elongated particles an inadequate gradation. When such a material replaces smooth and rounded natural sand grains in a concrete mix, the result is usually poor and much more water and cement has to be used to achieve adequate concrete flow. The consequences are huge stockpiles of the crushed fine fractions that can't be sold (mass balance problems) for the aggregate producers, sustainability problems for the whole industry and environmental issues for society due to dumping and storing of the fine co-generated material. There have been attempts of utilising the material in concrete before; however, they have mostly ended up in failure. There have been attempts to adjust the crushed sand to the properties of the natural sand, which would still give a lot of waste, especially if the grading would have to be adjusted and the high amounts of fines abundantly present in the crushed sand would have to be removed. Another fundamental reason for failure has been that historically such attempts have mainly ended up in a research carried out by people (both industrial and academic) with aggregate background (= parties willing to find market

  14. Corrosion Behavior of Steel Reinforcement in Concrete with Recycled Aggregates, Fly Ash and Spent Cracking Catalyst

    Directory of Open Access Journals (Sweden)

    Hebé Gurdián

    2014-04-01

    Full Text Available The main strategy to reduce the environmental impact of the concrete industry is to reuse the waste materials. This research has considered the combination of cement replacement by industrial by-products, and natural coarse aggregate substitution by recycled aggregate. The aim is to evaluate the behavior of concretes with a reduced impact on the environment by replacing a 50% of cement by industrial by-products (15% of spent fluid catalytic cracking catalyst and 35% of fly ash and a 100% of natural coarse aggregate by recycled aggregate. The concretes prepared according to these considerations have been tested in terms of mechanical strengths and the protection offered against steel reinforcement corrosion under carbonation attack and chloride-contaminated environments. The proposed concrete combinations reduced the mechanical performance of concretes in terms of elastic modulus, compressive strength, and flexural strength. In addition, an increase in open porosity due to the presence of recycled aggregate was observed, which is coherent with the changes observed in mechanical tests. Regarding corrosion tests, no significant differences were observed in the case of the resistance of these types of concretes under a natural chloride attack. In the case of carbonation attack, although all concretes did not stand the highly aggressive conditions, those concretes with cement replacement behaved worse than Portland cement concretes.

  15. The Feasibility of Palm Kernel Shell as a Replacement for Coarse Aggregate in Lightweight Concrete

    Science.gov (United States)

    Itam, Zarina; Beddu, Salmia; Liyana Mohd Kamal, Nur; Ashraful Alam, Md; Issa Ayash, Usama

    2016-03-01

    Implementing sustainable materials into the construction industry is fast becoming a trend nowadays. Palm Kernel Shell is a by-product of Malaysia’s palm oil industry, generating waste as much as 4 million tons per annum. As a means of producing a sustainable, environmental-friendly, and affordable alternative in the lightweight concrete industry, the exploration of the potential of Palm Kernel Shell to be used as an aggregate replacement was conducted which may give a positive impact to the Malaysian construction industry as well as worldwide concrete usage. This research investigates the feasibility of PKS as an aggregate replacement in lightweight concrete in terms of compressive strength, slump test, water absorption, and density. Results indicate that by using PKS for aggregate replacement, it increases the water absorption but decreases the concrete workability and strength. Results however, fall into the range acceptable for lightweight aggregates, hence it can be concluded that there is potential to use PKS as aggregate replacement for lightweight concrete.

  16. A study on the performance of concrete containing recycled aggregates and ceramic as materials replacement

    Science.gov (United States)

    Azmi, N. B.; Khalid, F. S.; Irwan, J. M.; Anting, N.; Mazenan, P. N.

    2017-11-01

    Natural fine aggregate materials are commonly used in development and commercial construction in Malaysia. In fact, concrete production was increased as linear with the growing Malaysia economy. However, an issue was production of concrete was to locate adequate sources of natural fine aggregates. There lot of studies have been conducted in order to replace the fine aggregate in which natural fine aggregate replace with the waste material in concrete preparation. Therefore, this study aims to utilize the Recycled Concrete Aggregate (RCA) and ceramic waste which has great potential to replace the natural aggregate in concrete mix with different type of method, admixture, and parameters. This research were focused on compressive strength and water absorption test to determine the optimum mix ratio of concrete mix. The concrete aggregate was chosen due to improvement capillary bonding mechanisms and ceramic presented similar strength compared to the conventional concrete using natural aggregate. Percent of replacement have been used in this study was at 25%, 35% and 45% of the RCA and 5%, 10% and 15% for ceramic, respectively. Furthermore, this research was conduct to find the optimum percentage of aggregate replacement, using water-cement ratio of 0.55 with concrete grade 25/30. The best percentage of replacement was the RCA35% C15% with the compressive strength of 34.72 MPa and the water absorption was satisfied.

  17. Spall Strength Measurements of Concrete for Varying Aggregate Sizes

    International Nuclear Information System (INIS)

    Chhabildas, Lalit C.; Kipp, Marlin E.; Reinhart, William D.; Wilson, Leonard T.

    1999-01-01

    Controlled impact experiments have been performed to determine the spall strength of four different concrete compositions. The four concrete compositions are identified as, 'SAC-5, CSPC', (''3/4'') large, and (''3/8'') small, Aggregate. They differ primarily in aggregate size but with average densities varying by less than five percent. Wave profiles from sixteen experiments, with shock amplitudes of 0.07 to 0.55 GPa, concentrate primarily within the elastic regime. Free-surface particle velocity measurements indicate consistent pullback signals in the release profiles, denoting average span strength of approximately 40 MPa. It is the purpose of this paper to present spall measurements under uniaxial strain loading. Notwithstanding considerable wave structure that is a unique characteristic to the heterogeneous nature of the scaled concrete, the spall amplitudes appear reproducible and consistent over the pressure range reported in this study

  18. Study of mechanical properties and recommendations for the application of waste Bakelite aggregate concrete

    OpenAIRE

    Nopagon Usahanunth; Seree Tuprakay; Waranon Kongsong; Sirawan Ruangchuay Tuprakay

    2018-01-01

    Bakelite waste from industrial manufacturing may be a hazard to the environment and public health. The utilization of waste Bakelite (WB) to replace natural aggregates (NA), such as natural coarse aggregate (NCA) and natural fine aggregate (NFA), in concrete and mortar is an approach for reducing both waste plastic and natural material. This research examines the utilization of waste Bakelite aggregate (WBA) in concrete and mortar mixtures to form waste Bakelite aggregate concrete (WBAC) and ...

  19. Influence of surface modified basalt fiber on strength of cinder lightweight aggregate concrete

    Science.gov (United States)

    Xiao, Liguang; Li, Jiheng; Liu, Qingshun

    2017-12-01

    In order to improve the bonding and bridging effect between volcanic slag lightweight aggregate concrete cement and basalt fiber, The basalt fiber was subjected to etching and roughening treatment by NaOH solution, and the surface of the basalt fiber was treated with a mixture of sodium silicate and micro-silica powder. The influence of modified basalt fiber on the strength of volcanic slag lightweight aggregate concrete was systematically studied. The experimental results show that the modified basalt fiber volcanic slag lightweight aggregate concrete has a flexural strength increased by 47%, the compressive strength is improved by 16% and the toughness is increased by 27% compared with that of the non-fiber.

  20. A process for separating aggregate from concrete waste during the dismantlement of nuclear power plants

    International Nuclear Information System (INIS)

    Koga, Yasuo; Inoue, Toshikatsu; Tateyashiki, Hisashi; Sukekiyo, Mitsuaki; Okamoto, Masamichi; Asano, Touichi.

    1997-01-01

    The decommissioning and dismantling of nuclear power plants will produce a large quantity of non-active waste concrete. From the viewpoint of recycling of this waste concrete the recovery of aggregate contained in concrete at 80% and reuse of it into a new plant construction are envisioned. For these purposes we have studied the recovery process of aggregate from concrete composed of a heating step followed by a milling step onto waste concrete blocks. We have found that higher operation temperature brings a better effect for the separation of aggregate from a concrete body, however too high temperature may reversely degrade a quality of recovered aggregate itself. The most effective heating temperature which is considered not to give the damage to a quality of aggregate stays between 200-500degC. The effect of a duration at such temperature zone is relatively small. As a conclusion we have found that 300degC of heating temperature and 30-120 minutes of a duration in a rod mill with high efficiency of rubbing work for getting coarse aggregate and an agitate mill for fine aggregate might be proper operating conditions under which we can recover both coarse and fine aggregate with the quality within JASS 5N standard. (author)

  1. Impact Resistance of Recycled Aggregate Concrete with Single and Hybrid Fibers

    Directory of Open Access Journals (Sweden)

    Ismail Sallehan

    2016-01-01

    Full Text Available This paper presents a recycled aggregate concrete (RAC mix that has been modified by adding treated recycled concrete aggregate (RCA and various types of fiber-reinforced systems. The effectiveness of these modifications in terms of energy absorption and impact resistance was evaluated and compared with that of the corresponding regular concrete, as well as with unmodified RAC specimens. Results clearly indicate that although modification of the RAC mix with treated RCA significantly enhances the impact resistance of RAC, further diversification with additional fiber, particularly those in hybrid form, can optimize the results.

  2. Using the accelerated Brazilian concrete prism test (ABCPT to evaluate alkali aggregate reaction (AAR

    Directory of Open Access Journals (Sweden)

    L. Sanchez

    Full Text Available There are many test methods used in the laboratory to detect potential alkali-aggregate reactions (AAR. However, up to now, there is no consensus if they are reliable and efficient. This work presents the development of a new and accelerated concrete prism test called ABCPT (accelerate Brazilian concrete prism test as an attempt to create a reliable and fast test that can analyze and classify the potential reactivity of aggregates in the laboratory. For this research, six aggregates from different lithotypes were used. The methods CPT, ACPT and ABCPT were carried out with all the aggregates and a comparative analysis among all tests was performed. ABCPT seems to have a great potential to analyze and classify aggregates in the laboratory, although it needs further testing with other lithotypes to be confirmed as feasible.

  3. Leaching and mechanical behaviour of concrete manufactured with recycled aggregates.

    Science.gov (United States)

    Sani, D; Moriconi, G; Fava, G; Corinaldesi, V

    2005-01-01

    The reuse of debris from building demolition is of increasing public interest because it decreases the volume of material to be disposed to landfill. This research is focused on the evaluation of the possibility of reusing recycled aggregate from construction or demolition waste (C&D) as a substitute for natural aggregate in concrete production. In most applications, cement based materials are used for building construction due to their cost effectiveness and performance; however their impact on the surrounding environment should be monitored. The interstitial pore fluid in contact with hydrated cementitious materials is characterized by persistent alkaline pH values buffered by the presence of hydrate calcium silicate, portlandite and alkaline ions. An experimental plan was carried out to investigate concrete structural properties in relation to alkali release in aqueous solution. Results indicate that the presence of recycled aggregate increases the leachability of unreactive ions (Na, K, Cl), while for calcium the substitution resulted in a lower net leaching. In spite of the lower mechanical resistance (40% less), such a waste concrete may be suggested as more environmentally sustainable.

  4. STUDY ON IMPACT AND TENSILE PROPERTIES OF CONCRETE WITH COCONUT SHELL AS COARSE AGGREGATE

    OpenAIRE

    R. Ranjith*

    2017-01-01

    The mechanical properties of coconut shell aggregate concrete (CSAC) namely splitting tensile strength, impact strength have been determined and a comparison is made with conventional granite aggregate concrete (CGAC) in the 30 days short-term experimental investigation. From the test results it is observed that coconut shell aggregate concrete has considerably sufficient strength. But the splitting tensile strength of coconut shell aggregate concrete is 50 % less than that of conventional gr...

  5. Study on the durability of concrete using granulated blast furnace slag as fine aggregate

    Science.gov (United States)

    Shi, Dongsheng; Liu, Qiang; Xue, Xinxin; He, Peiyuan

    2018-03-01

    In order to assessing the durability of concrete using granulated blastfurnace slag (GBS) as fine aggregate and compare it with natural river sand concrete, three different size of specimen were produced by using the same mix proportion with 3 different water cement ratios and 3 replacement ratios, and using it to measure the three aspects on the durability of concrete including freeze-thaw performance, dry-shrinkage performance and anti-chloride-permeability performance. In this paper. The test results show that using GBS as fine aggregate can slightly improve anti-chloride-permeability performance and dry-shrinkage performance of concrete in the condition of low water cement ratio, on the other hand, using GBS or natural river sand as fine aggregate has almost similar durability of concrete.

  6. Impact load-induced micro-structural damage and micro-structure associated mechanical response of concrete made with different surface roughness and porosity aggregates

    International Nuclear Information System (INIS)

    Erdem, Savaş; Dawson, Andrew Robert; Thom, Nicholas Howard

    2012-01-01

    The relationship between the nature of micro damage under impact loading and changes in mechanical behavior associated with different microstructures is studied for concretes made with two different coarse aggregates having significant differences mainly in roughness and porosity — sintered fly ash and uncrushed gravel. A range of techniques including X-ray diffraction, digital image analysis, mercury porosimetry, X-ray computed tomography, laser surface profilometry and scanning electron microscopy were used to characterize the aggregates and micro-structures. The concrete prepared with lightweight aggregates was stronger in compression than the gravel aggregate concrete due to enhanced hydration as a result of internal curing. In the lightweight concrete, it was deduced that an inhomogeneous micro-structure led to strain incompatibilities and consequent localized stress concentrations in the mix, leading to accelerated failure. The pore structure, compressibility, and surface texture of the aggregates are of paramount importance for the micro-cracking growth.

  7. Data on optimum recycle aggregate content in production of new structural concrete.

    Science.gov (United States)

    Paul, Suvash Chandra

    2017-12-01

    This data presented herein are the research summary of "mechanical behavior and durability performance of concrete containing recycled concrete aggregate" (Paul, 2011) [1]. The results reported in this article relate to an important parameter of optimum content of recycle concrete aggregate (RCA) in production of new concrete for both structural and non-structural applications. For the purpose of the research various types of physical, mechanical and durability tests are performed for concrete made with different percentages of RCA. Therefore, this data set can be a great help of the readers to understand the mechanism of RCA in relates to the concrete properties.

  8. Optimization of Packing Density of M30 Concrete With Steel Slag As Coarse Aggregate Using Fuzzy Logic

    Directory of Open Access Journals (Sweden)

    Arivoli M.

    2017-09-01

    Full Text Available Concrete plays a vital role in the design and construction of the infrastructure. To meet the global demand of concrete in future, it is becoming a challenging task to find suitable alternatives to natural aggregates. Steel slag is a by-product of steel making process. The steel slag aggregates are characterized by studying particle size and shape, physical and chemical properties, and mechanical properties as per IS: 2386-1963. The characterization study reveals the better performance of steel slag aggregate over natural coarse aggregate. M30 grade of concrete is designed and natural coarse aggregate is completely replaced by steel slag aggregate. Packing density of aggregates affects the characteristics of concrete. The present paper proposes a fuzzy system for concrete mix proportioning which increases the packing density. The proposed fuzzy system have four sub fuzzy system to arrive compressive strength, water cement ratio, ideal grading curve and free water content for concrete mix proportioning. The results show, the concrete mix proportion of the given fuzzy model agrees with IS method. The comparison of results shows that both proposed fuzzy system and IS method, there is a remarkable increase in compressive strength and bulk density, with increment in the percentage replacement of steel slag.

  9. Evaluation of the environmental, material, and structural performance of recycled aggregate concrete

    Science.gov (United States)

    Michaud, Katherine Sarah

    Concrete is the most commonly used building material in the construction industry, and contributes to 52% of construction and demolition waste in Canada. Recycled concrete aggregate (RCA) is one way to reduce this impact. To evaluate the performance of coarse and granular (fine and coarse) RCA in structural concrete applications, four studies were performed: an environmental assessment, a material testing program, a shear performance study, and a flexural performance study. To determine the environmental benefits of recycled aggregate concrete (RAC), three case studies were investigated using different populations and proximities to city centres. Environmental modelling suggested that RCA replacement could result in energy savings and greenhouse gas emission reductions, especially in remote areas. Tests were performed to determine if the volumetric replacement of up to 30% coarse RCA and 20% granular RCA is suitable for structural concrete applications in Canada. Fresh, hardened, and durability properties were evaluated. All five (5) of the RCA mixes showed equivalent material performance to the control mixes and met the requirements for a structural concrete mix. The five (5) RAC mixes were also used in structural testing. One-way reinforced concrete slab specimens were tested to failure to evaluate the shear and flexural performance of the RAC members. Peak capacities of and crack formation within each member were analyzed to evaluate the performance of RAC compared to conventional concrete. The shear capacity of specimens made from four (4) of the five (5) RAC mixtures was higher or equivalent to the control specimens. Specimens of the concrete mixture containing the highest content of recycled aggregate, 20% volumetric replacement of granular RCA, had shear capacities 14.1% lower, and exhibited cracking at lower loads than the control. The average flexural capacities of all RAC specimens were within 3.7% of the control specimens. Results from this research

  10. Preliminary laboratory investigation of thermally treated recycled concrete aggregate for general use in concrete

    NARCIS (Netherlands)

    Larbi, J.A.; Heijnen, W.M.M.; Brouwer, J.P.; Mulder, E.

    2000-01-01

    This paper deals with a preliminary laboratory study to assess the effectiveness of thermal treatment methods to improve the quality of recycled concrete aggregate. The samples used for the study consisted of sieved fractions of crushed concrete that were subjected to various thermal treatments at

  11. Flexural Behaviour Of Reinforced Concrete Beams Containing Expanded Glass As Lightweight Aggregates

    Directory of Open Access Journals (Sweden)

    Khatib Jamal

    2015-12-01

    Full Text Available The flexural properties of reinforced concrete beams containing expanded glass as a partial fine aggregate (sand replacement are investigated. Four concrete mixes were employed to conduct this study. The fine aggregate was replaced with 0%, 25%, 50% and 100% (by volume expanded glass. The results suggest that the incorporation of 50% expanded glass increased the workability of the concrete. The compressive strength was decreasing linearly with the increasing amount of expanded glass. The ductility of the concrete beam significantly improved with the incorporation of the expanded glass. However, the load-carrying capacity of the beam and load at which the first crack occurs was reduced. It was concluded that the inclusion of expanded glass in structural concrete applications is feasible.

  12. Thermal properties of light-weight concrete with waste polypropylene aggregate

    Science.gov (United States)

    Záleská, Martina; Pokorný, Jaroslav; Pavlíková, Milena; Pavlík, Zbyšek

    2017-07-01

    Thermal properties of a sustainable light-weight concrete incorporating high volume of waste polypropylene as partial substitution of natural aggregate were studied in the paper. Glass fiber reinforced polypropylene (GFPP), a by-product of PP tubes production, partially substituted fine natural silica aggregate in 10, 20, 30, 40, and 50 mass%. In order to quantify the effect of GFPP use on concrete properties, a reference concrete mix without plastic waste was studied as well. For the applied GFPP, bulk density, matrix density, and particle size distribution were measured. Specific attention was paid to thermal transport and storage properties of GFPP that were examined in dependence on compaction time. For the developed light-weight concrete, thermal properties were accessed using transient impulse technique, whereas the measurement was done in dependence on moisture content, from the dry state to fully water saturated state. Additionally, the investigated thermal properties were plotted as function of porosity. The tested light-weight concrete was found to be prospective construction material possessing improved thermal insulation function. Moreover, the reuse of waste plastics in concrete composition was beneficial both from the environmental and financial point of view considering plastics low biodegradability and safe disposal.

  13. Lightweight self-compacting concrete with light expanded clay aggregate (LECA

    Directory of Open Access Journals (Sweden)

    Heiza Khaled

    2018-01-01

    Full Text Available Lightweight concretes have been successfully applied in building constructions for many years due to their favorable material properties, particularly their low specific weight in connection with a high strength, a high capability of thermal insulation and a high durability. The development leading to lightweight self-compacting concrete (LWSCC represents an important advanced step within the recent years. This concrete combines the favorable properties of a lightweight concrete with those of a self-compacting concrete. Research work is aimed on development of (LWSCC with the use of light aggregates “Light expanded clay aggregate (LECA”. In this research, first by specific gravity factor method, twenty different mix designs of (LWSCC were cast and tested to find out the values of slump flow, J-ring , V-funnel and 28 day compressive strength. Based on the results obtained, the best mix design was selected for further investigation. This paper also focuses on studying the effect of changing the reinforcement ratio on reinforced two way slabs when the dimensions were kept constant.

  14. Eco-friendly porous concrete using bottom ash aggregate for marine ranch application.

    Science.gov (United States)

    Lee, Byung Jae; Prabhu, G Ganesh; Lee, Bong Chun; Kim, Yun Yong

    2016-03-01

    This article presents the test results of an investigation carried out on the reuse of coal bottom ash aggregate as a substitute material for coarse aggregate in porous concrete production for marine ranch applications. The experimental parameters were the rate of bottom ash aggregate substitution (30%, 50% and 100%) and the target void ratio (15%, 20% and 25%). The cement-coated granular fertiliser was substituted into a bottom ash aggregate concrete mixture to improve marine ranch applications. The results of leaching tests revealed that the bottom ash aggregate has only a negligible amount of the ten deleterious substances specified in the Ministry of Environment - Enforcement Regulation of the Waste Management Act of Republic Korea. The large amount of bubbles/air gaps in the bottom ash aggregate increased the voids of the concrete mixtures in all target void ratios, and decreased the compressive strength of the porous concrete mixture; however, the mixture substituted with 30% and 10% of bottom ash aggregate and granular fertiliser, respectively, showed an equal strength to the control mixture. The sea water resistibility of the bottom ash aggregate substituted mixture was relatively equal to that of the control mixture, and also showed a great deal of improvement in the degree of marine organism adhesion compared with the control mixture. No fatality of fish was observed in the fish toxicity test, which suggested that bottom ash aggregate was a harmless material and that the combination of bottom ash aggregate and granular fertiliser with substitution rates of 30% and 10%, respectively, can be effectively used in porous concrete production for marine ranch application. © The Author(s) 2015.

  15. Effect of aggregate graining compositions on skid resistance of Exposed Aggregate Concrete pavement

    Science.gov (United States)

    Wasilewska, Marta; Gardziejczyk, Wladysław; Gierasimiuk, Pawel

    2018-05-01

    The paper presents the evaluation of skid resistance of EAC (Exposed Aggregate Concrete) pavements which differ in aggregate graining compositions. The tests were carried out on concrete mixes with a maximum aggregate size of 8 mm. Three types of coarse aggregates were selected depending on their resistance to polishing which was determined on the basis of the PSV (Polished Stone Value). Basalt (PSV 48), gabbro (PSV 50) and trachybasalt (PSV 52) aggregates were chosen. For each type of aggregate three graining compositions were designed, which differed in the content of coarse aggregate > 4mm. Their content for each series was as follows: A - 38%, B - 50% and C - 68%. Evaluation of the skid resistance has been performed using the FAP (Friction After Polishing) test equipment also known as the Wehner/Schulze machine. Laboratory method enables to compare the skid resistance of different types of wearing course under specified conditions simulating polishing processes. In addition, macrotexture measurements were made on the surface of each specimen using the Elatexure laser profile. Analysis of variance showed that at significance level α = 0.05, aggregate graining compositions as well as the PSV have a significant influence on the obtained values of the friction coefficient μm of the tested EAC pavements. The highest values of the μm have been obtained for EAC with the lowest amount of coarse aggregates (compositions A). In these cases the resistance to polishing of the aggregate does not significantly affect the friction coefficients. This is related to the large areas of cement mortar between the exposed coarse grains. Based on the analysis of microscope images, it was observed that the coarse aggregates were not sufficiently exposed. It has been proved that PSV significantly affected the coefficient of friction in the case of compositions B and C. This is caused by large areas of exposed coarse aggregate. The best parameters were achieved for the EAC pavements

  16. Potential of waste tires as aggregates in concrete | Mutuku | Journal ...

    African Journals Online (AJOL)

    Potential use of this kind of concrete includes nonstructural purposes such as lightweight concrete walls and blocks, building facades and crash barriers. Keywords: concrete aggregates, rubber chips, rubberized concrete, used tires, waste recycling. Journal of Civil Engineering Research and Practice Vol. 3(1) 2006: 75-84 ...

  17. Influence of aggregate characteristics on the compressive strength of normal weight concrete

    International Nuclear Information System (INIS)

    Qureshi, M.A.; Aslam, M.

    2015-01-01

    Experimental investigations on the properties of concrete have been performed around the globe and their correlation is interpreted in relevant design codes. The structural behavior of cement concrete significantly relies on the material resources, properties of the aggregates constituting the concrete and the local construction practice. These factors vary from place to place. Therefore, the compressive strength of concrete prepared from the aggregates available in one locality may not be directly applicable to the other areas. The purpose of this study is to evaluate the Influence of locally available coarse aggregates on the compressive strength of normal weight concrete (NWC) prepared under local environmental conditions of district Khairpur Mir's, Sindh, Pakistan. The coarse aggregates were collected from five different quarries in the vicinity of Khairpur Mir's, Pakistan. In total; 180 cubes were tested. 10 different batches were formed in order to arrange individual characterization of concrete. Each batch was contained of 18 cubes and each quarry contains 2 batches making a total of 36 cube with four different ratios for each quarry. Dry density and compressive strength of concrete was calculated and a comparison is provided as a guideline for the future construction work in the local community. (author)

  18. Environmental suitability of recycled concrete aggregate in highways : [research summary].

    Science.gov (United States)

    2015-01-01

    Natural highway aggregate is a finite resource that with continued use in construction : activities but some good quality aggregates used in existing concrete structures may be : re-used to replace with the natural aggregate. Due to the repair or rep...

  19. Application of orthogonal test method in mix proportion design of recycled lightweight aggregate concrete

    Science.gov (United States)

    Zhao, Zhanshan; An, Le; Zhang, Yijing; Yuan, Jie

    2017-03-01

    Recycled lightweight aggregate concrete was made with construction waste and ceramsite brick mainly including brick. Using the orthogonal test method, the mix proportion of recycled lightweight aggregate concrete was studied, and the Influence regularity and significance of water binder ratio, fly ash, sand ratio, the amount of recycled aggregate proportion on the compressive strength of concrete, the strong influence of mass ratio, slump expansion degree was studied. Through the mean and range analysis of the test results, the results show that the water binder ratio has the greatest influence on the 28d intensity of recycled lightweight aggregate concrete. Secondly, the fly ash content, the recycled aggregate replacement rate and the sand ratio have little influence. For the factors of expansion: the proportion of fly ash = water binder ratio sand >sand rate> recycled aggregate replacement rate. When the content of fly ash is about 30%, the expanded degree of recycled lightweight aggregate concrete is the highest, and the workability of that is better and the strength of concrete with 28d and 56d are the highest. When the content of brickbat is about 40% brick particles, the strength of concrete reaches the highest.

  20. Properties of Recycled Aggregate Concrete Reinforced with Polypropylene Fibre

    Directory of Open Access Journals (Sweden)

    Wan Mohammad Wan Nur Syazwani

    2016-01-01

    Full Text Available This research work is aimed to investigate how the addition of various proportion of polypropylene fibre affects the mechanical strength and permeability characteristics of recycled aggregate concrete (RAC which has been produced with treated coarse recycled concrete aggregate (RCA. Further research on RAC properties and their applications is of great importance as the scarcity of virgin aggregate sources in close proximity to major urban centers is becoming a worldwide problem. In this study, the hardened RAC properties at the curing age of 7 and 28 days such as compressive strength, flexural strength, ultrasonic pulse velocity (UPV, water absorption and total porosity were evaluated and compare with control specimens. Experimental result indicates that although the inclusion of the treated coarse RCA can enhance the mechanical strength and permeability properties of RAC, Further modification by addition of polypropylene fibre can optimize the results.

  1. Aggregate assesment and durability evaluation of optimized graded concrete in the state of Oklahoma

    Science.gov (United States)

    Ghaeezadeh, Ashkan

    This research is a part of a larger project that emphasizes on creating a more scientific approach to designing concrete mixtures for concrete pavements that use less cement and more aggregate which is called optimized graded concrete. The most challenging obstacle in optimized mixtures is reaching enough workability so that one doesn't have to add more cement or super-plasticizer to reach the desired level of flowability. Aggregate gradation and characteristics have found to be very important when it comes to the workabaility of optimized graded concrete. In this research a new automated method of aggregate assessment was used to compare the shape and the surface of different aggregates as well as their influence on the concrete flowability. At the end, the performance of optimized graded concrete against drying shrinkage and freezing and thawing condition were investigated.

  2. AN EXPERIMENTAL STUDY ON STRENGTH PARAMETRES OF CONCRETE WITH REPLACMENT OF FINE AGGREGATE BY ROBO SAND

    OpenAIRE

    T.Dilip Kumar *1 & G.Kalyan 2

    2018-01-01

    Concrete is the most widely used composite construction material. Fine aggregate plays a very important role for imparting better properties to concrete in its fresh and hardened state. Generally, river sand was used as fine aggregate for construction. Due to the continuous mining of sand from riverbed led to the depletion of river sand and it became a scarce material. Also, samining from river bed caused a lot of environmental issues. As a substitute to river sand, Robo sand has been used. I...

  3. Effects of aggregate grading on the properties of steel fibre-reinforced concrete

    Science.gov (United States)

    Acikgens Ulas, M.; Alyamac, K. E.; Ulucan, Z. C.

    2017-09-01

    This study investigates the effects of changing the aggregate grading and maximum aggregate size (D max ) on the workability and mechanical properties of steel fibre-reinforced concrete (SFRC). Four different gradations and two different D max were used to produce SFRC mixtures with constant cement dosages and water/cement ratios. Twelve different concrete series were tested. To observe the properties of fresh concrete, slump and Ve-Be tests were performed immediately after the mixing process to investigate the effects of time on workability. The hardened properties, such as the compressive, splitting tensile and flexural strengths, were also evaluated. In addition, the toughness of the SFRC was calculated. Based on our test results, we can conclude that the grading of the aggregate and the D max have remarkable effects on the properties of fresh and hardened SFRC. In addition, the toughness of the SFRC was influenced by changing the grading of the aggregate and the D max .

  4. Application of Glass Fiber Waste Polypropylene Aggregate in Lightweight Concrete – thermal properties

    Science.gov (United States)

    Citek, D.; Rehacek, S.; Pavlik, Z.; Kolisko, J.; Dobias, D.; Pavlikova, M.

    2018-03-01

    Actual paper focus on thermal properties of a sustainable lightweight concrete incorporating high volume of waste polypropylene aggregate as partial substitution of natural aggregate. In presented experiments a glass fiber reinforced polypropylene (GFPP) which is a by-product of PP tubes production, partially substituted fine natural silica aggregate in 10, 20, 30, 40 and 50 mass %. Results were compared with a reference concrete mix without plastic waste in order to quantify the effect of GFPP use on concrete properties. Main material physical parameters were studied (bulk density, matrix density without air content, and particle size distribution). Especially a thermal transport and storage properties of GFPP were examined in dependence on compaction time. For the developed lightweight concrete, thermal properties were accessed using transient impulse technique, where the measurement was done in dependence on moisture content (from the fully water saturated state to dry state). It was found that the tested lightweight concrete should be prospective construction material possessing improved thermal insulation function and the reuse of waste plastics in concrete composition was beneficial both from the environmental and financial point of view.

  5. Effect of Fly-Ash on Corrosion Resistance Characteristics of Rebar Embedded in Recycled Aggregate Concrete

    Science.gov (United States)

    Revathi, Purushothaman; Nikesh, P.

    2018-04-01

    In the frame of an extended research programme dealing with the utilization of recycled aggregate in concrete, the corrosion resistance characteristics of rebars embedded in recycled aggregate concrete is studied. Totally five series of concrete mixtures were prepared with fly-ash as replacement for cement in the levels of 10-30% by weight of cement. Corrosion studies by 90 days ponding test, linear polarization test and impressed voltage tests were carried out, in order to investigate whether corrosion behaviour of the rebars has improved due to the replacement of cement with fly-ash. Results showed that the replacement of cement with fly-ash in the range of 20-30% improves the corrosion resistance characteristics of recycled aggregate concrete.

  6. Creep and shrinkage behaviour of concrete with mixed recycled aggregates

    NARCIS (Netherlands)

    Hordijk, D.A.; Uijl, J. den

    1999-01-01

    For environmental reasons the interest in possibilities to use recycled aggregates in concrete is strongly increasing. World-wide, most attention with respect to recycled aggregates is paid to the quality of the aggregates. Still only limited information is available for the mechanica! properties of

  7. A closed-loop life cycle assessment of recycled aggregate concrete utilization in China.

    Science.gov (United States)

    Ding, Tao; Xiao, Jianzhuang; Tam, Vivian W Y

    2016-10-01

    This paper studies the potential environmental impact of recycled coarse aggregate (RCA) for concrete production in China. According to the cradle-to-cradle theory, a closed-loop life cycle assessment (LCA) on recycled aggregate concrete (RAC) utilization in China with entire local life cycle inventory (LCI) is performed, regarding the environmental influence of cement content, aggregate production, transportation and waste landfilling. Special attention is paid on the primary resource and energy conservation, as well as climate protection induced by RAC applications. Environmental impact between natural aggregate concrete (NAC) and RAC are also compared. It is shown that cement proportion and transportation are the top two contributors for carbon dioxide (CO2) emissions and energy consumption for both NAC and RAC. Sensitivity analysis also proves that long delivery distances for natural coarse aggregate (NCA) leave a possible opportunity for lowering environmental impact of RAC in China. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Compressive Strength and Modulus of Elasticity of Concrete with Cubed Waste Tire Rubbers as Coarse Aggregates

    Science.gov (United States)

    Haryanto, Y.; Hermanto, N. I. S.; Pamudji, G.; Wardana, K. P.

    2017-11-01

    One feasible solution to overcome the issue of tire disposal waste is the use of waste tire rubber to replace aggregate in concrete. We have conducted an experimental investigation on the effect of rubber tire waste aggregate in cuboid form on the compressive strength and modulus of elasticity of concrete. The test was performed on 72 cylindrical specimens with the height of 300 mm and diameter of 150 mm. We found that the workability of concrete with waste tire rubber aggregate has increased. The concrete density with waste tire rubber aggregate was decreased, and so was the compressive strength. The decrease of compressive strength is up to 64.34%. If the content of waste tire rubber aggregate is more than 40%, then the resulting concrete cannot be categorized as structural concrete. The modulus of elasticity decreased to 59.77%. The theoretical equation developed to determine the modulus of elasticity of concrete with rubber tire waste aggregate has an accuracy of 84.27%.

  9. Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, A. [Centre de Recherche sur les Infrastructures en Beton (CRIB), Universite Laval, 1065 ave de la Medecine, Quebec, QC, Canada G1V 0A6 (Canada); Duchesne, J., E-mail: josee.duchesne@ggl.ulaval.ca [Centre de Recherche sur les Infrastructures en Beton (CRIB), Universite Laval, 1065 ave de la Medecine, Quebec, QC, Canada G1V 0A6 (Canada); Fournier, B. [Centre de Recherche sur les Infrastructures en Beton (CRIB), Universite Laval, 1065 ave de la Medecine, Quebec, QC, Canada G1V 0A6 (Canada); Durand, B. [Institut de recherche d' Hydro-Quebec (IREQ), 1740 boul. Lionel-Boulet, Varennes, QC, Canada J3X 1S1 (Canada); Rivard, P. [Universite de Sherbrooke, Sherbrooke, QC, Canada J1K 2R1 (Canada); Shehata, M. [Ryerson University, 350 Victoria Street, Toronto, ON, Canada M5B 2K3 (Canada)

    2012-10-15

    Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivieres area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damaged concrete include 'rust' mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH{sub 2}O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.

  10. Mineralogical and chemical assessment of concrete damaged by the oxidation of sulfide-bearing aggregates: Importance of thaumasite formation on reaction mechanisms

    International Nuclear Information System (INIS)

    Rodrigues, A.; Duchesne, J.; Fournier, B.; Durand, B.; Rivard, P.; Shehata, M.

    2012-01-01

    Damages in concrete containing sulfide-bearing aggregates were recently observed in the Trois-Rivières area (Quebec, Canada), characterized by rapid deterioration within 3 to 5 years after construction. A petrographic examination of concrete core samples was carried out using a combination of tools including: stereomicroscopic evaluation, polarized light microscopy, scanning electron microscopy, X-ray diffraction and electron microprobe analysis. The aggregate used to produce concrete was an intrusive igneous rock with different metamorphism degrees and various proportions of sulfide minerals. In the rock, sulfide minerals were often surrounded by a thin layer of carbonate minerals (siderite). Secondary reaction products observed in the damaged concrete include “rust” mineral forms (e.g. ferric oxyhydroxides such as goethite, limonite (FeO (OH) nH 2 O) and ferrihydrite), gypsum, ettringite and thaumasite. In the presence of water and oxygen, pyrrhotite oxidizes to form iron oxyhydroxides and sulphuric acid. The acid then reacts with the phases of the cement paste/aggregate and provokes the formation of sulfate minerals. Understanding both mechanisms, oxidation and internal sulfate attack, is important to be able to duplicate the damaging reaction in laboratory conditions, thus allowing the development of a performance test for evaluating the potential for deleterious expansion in concrete associated with sulfide-bearing aggregates.

  11. Study of mechanical properties and recommendations for the application of waste Bakelite aggregate concrete

    Directory of Open Access Journals (Sweden)

    Nopagon Usahanunth

    2018-06-01

    Full Text Available Bakelite waste from industrial manufacturing may be a hazard to the environment and public health. The utilization of waste Bakelite (WB to replace natural aggregates (NA, such as natural coarse aggregate (NCA and natural fine aggregate (NFA, in concrete and mortar is an approach for reducing both waste plastic and natural material. This research examines the utilization of waste Bakelite aggregate (WBA in concrete and mortar mixtures to form waste Bakelite aggregate concrete (WBAC and waste Bakelite mortar (WBM. The tests cover the physical and chemical properties of WBA, the mechanical properties of WBAC and WBM (including the extraction of chemical substances from WBA utilization to replace NCA and NFA, and recommendations for the application of replacement. The results indicate that WBA particles of different sizes can replace both fine and coarse natural aggregates. Its weight is less than natural aggregate but the absorption rate is higher. As for recommendations for the application, it was found that replacing 20% of NCA with waste Bakelite coarse aggregate in concrete (WBAC-RNCA was the most suitable proportion, owing to its mechanical properties and safety for the environment and public health, and because its material cost is acceptable. However, the use of waste Bakelite fine aggregate to replace NFA (WBAC-RNFA in concrete is not appropriate, because its mechanical properties are not sufficient, and it is considered unsafe for the environment and health. Moreover, WBM is not a suitable material for plastering work, since it may be a hazard to the environment and public health, and its cost is higher than conventional mortar. Keywords: Waste Bakelite, Aggregate, Concrete, Mortar

  12. Evaluation of the use of steelmaking slag as an aggregate in concrete mix: A factorial design approach

    Directory of Open Access Journals (Sweden)

    Aljbour Salah H.

    2017-01-01

    Full Text Available Slag is investigated towards its potential use as an aggregate in concrete mix production. Full factorial design methodology is applied to study the effect of two process input variables, namely: slag as coarse aggregate and slag as medium aggregate on the properties of concrete mix. Additionally, the interaction between input variables is also examined. Incorporating steel slag aggregate in the concrete mix affected its compressive strength. Enhanced compressive strength concrete mix was obtained with 70 wt.% coarse slag aggregate and 70 wt.% medium slag aggregate. Under these proportions, the 28-days compressive strength was higher than the 28-days compressive strength of a concrete mix prepared from normal aggregate. Strong interaction effect exists between slag aggregate size on the compressive strength at 7-days curing. Lower compressive strength for the concrete mix might be obtained if improper proportions of mixed medium and coarse slag aggregate were employed.

  13. Influence of Selected Factors on the Relationship between the Dynamic Elastic Modulus and Compressive Strength of Concrete.

    Science.gov (United States)

    Jurowski, Krystian; Grzeszczyk, Stefania

    2018-03-22

    In this paper, the relationship between the static and dynamic elastic modulus of concrete and the relationship between the static elastic modulus and compressive strength of concrete have been formulated. These relationships are based on investigations of different types of concrete and take into account the type and amount of aggregate and binder used. The dynamic elastic modulus of concrete was tested using impulse excitation of vibration and the modal analysis method. This method could be used as a non-destructive way of estimating the compressive strength of concrete.

  14. Influence of Selected Factors on the Relationship between the Dynamic Elastic Modulus and Compressive Strength of Concrete

    Science.gov (United States)

    Jurowski, Krystian; Grzeszczyk, Stefania

    2018-01-01

    In this paper, the relationship between the static and dynamic elastic modulus of concrete and the relationship between the static elastic modulus and compressive strength of concrete have been formulated. These relationships are based on investigations of different types of concrete and take into account the type and amount of aggregate and binder used. The dynamic elastic modulus of concrete was tested using impulse excitation of vibration and the modal analysis method. This method could be used as a non-destructive way of estimating the compressive strength of concrete. PMID:29565830

  15. Long-term deflection and flexural behavior of reinforced concrete beams with recycled aggregate

    International Nuclear Information System (INIS)

    Choi, Won-Chang; Yun, Hyun-Do

    2013-01-01

    Highlights: • Long-term deformation of recycled aggregate concrete beams was examined. • Three beams were monitored for over 380 days. • Influence of recycled aggregate on the long-term performance. • Comparison of that between normal and recycled aggregate concrete beams. - Abstract: This paper presents experimental results on the long-term deformations of recycled aggregate concrete (RAC) beams for over 1 year (380 days) and flexural behavior of RAC beams after exposure to sustained loading. Three reinforced concrete (RC) beam specimens were fabricated with replacement percentage of aggregate (100% natural aggregate, 100% recycled coarse aggregate, and 50% recycled fine aggregate) and subjected to sustained loading that is 50% of the nominal flexural capacity. During the sustained loading period (380 days), the long-term deflection due to creep and shrinkage was recorded and compared with predicted behavior that was determined based on current specifications (ACI 318 Code). After measuring the long-term deflection for 380 days, four-point bending tests were conducted to investigate the flexural behavior of RC beams after exposure to sustained loading and determine any reduction in flexural capacity. A modified equation to predict the long-term deflection values for RC beams with recycled aggregate is proposed, and the experimental results are compared with the predictions calculated using the ACI 318 Code provisions

  16. Application of life cycle assessment to production processes of environmentally sustainable concrete, prepared with artificial aggregates

    International Nuclear Information System (INIS)

    Vaccaro, R.; Colangelo, F.; Palumbo, M.; Cioffi, R.

    2005-01-01

    This paper is about the application of Life Cycle Assessment (L.C.A.) on environmentally sustainable concrete production processes. The goal of this experimentations is to assess environmental impact and energy demand related to concrete production, by using, in different admixtures, natural and artificial aggregates, belonging from treatments of different kind of industrial wastes characterized by very small particle sizes. Particular attention was concentrated on the utilization of fine fraction since it is difficult to recover in usual fields of recycling (i.e. aggers, crowl spaces, etc.). This study follows the approach from cradle to cradle. This experimentation was conducted in relation to four concrete admixtures produced, one of them containing only natural aggregate, and the other ones obtained by substituting the 10% of aggregate respectively with inert wastes as construction and demolition waste (CeD waste). cement kiln dust (CKD) and marble sludge. For all admixtures six different end-life scenarios have been proposed, one of them considers all materials transported in landfill while the other ones consider a partial transportation on landfill (15%) and a recycle of the 85% of wastes obtained after demolition of structures [it

  17. Effects of waste PET bottles aggregate on the properties of concrete

    International Nuclear Information System (INIS)

    Choi, Yun-Wang; Moon, Dae-Joong; Chung, Jee-Seung; Cho, Sun-Kyu

    2005-01-01

    This paper investigates the surface microstructure of waste polyethylene terephthalate (PET) bottles lightweight aggregate (WPLA) to examine the effect of granulated blast-furnace slag (GBFS) on WPLA. The WPLA was made from the waste PET bottles and GBFS, and experimental tests were conducted on compressive strength, splitting tensile strength, modulus of elasticity, slump, and density of waste PET bottles lightweight aggregate concrete (WPLAC). The 28-day compressive strength of WPLAC with the replacement ratio of 75% reduces about 33% compared to the control concrete in the water-cement ratio of 45%. The density of WPLAC varies from 1940 to 2260 kg/m 3 by the influence of WPLA. The structural efficiency of WPLAC decreases as the replacement ratio increases. The workability of concrete with 75% WPLA improves about 123% compared to that of the normal concrete in the water-cement ratio of 53%. The adhered GBFS is able to strengthen the surface of WPLA and to narrow the transition zone owing to the reaction with calcium hydroxide

  18. Study of the fracture behavior of mortar and concretes with crushed rock or pebble aggregates

    Directory of Open Access Journals (Sweden)

    Sebastião Ribeiro

    2011-03-01

    Full Text Available The objective of this work was to compare the fracture energy of mortar and concretes produced with crushed rock and pebble aggregates using zero, 10, 20, 30 and 40% of aggregates mixed with standard mortar and applying the wedge splitting method to achieve stable crack propagation. The samples were cast in a special mold and cured for 28 days, after which they were subjected to crack propagation tests by the wedge splitting method to determine the fracture energies of the mortar and concrete. The concretes showed higher fracture energy than the mortar, and the concretes containing crushed rock showed higher resistance to crack propagation than all the compositions containing pebbles. The fracture energy varied from 38 to 55 J.m-2. A comparison of the number of aggregates that separated from the two concrete matrices with the highest fracture energies indicated that the concrete containing pebbles crumbled more easily and was therefore less resistant to crack propagation.

  19. Evaluation of using crushed brick as coarse aggregate in concrete layer within rigid highway pavement

    Directory of Open Access Journals (Sweden)

    Alwash Ali

    2018-01-01

    Full Text Available Most of the present studies related to the field of highway pavement construction technique tend to make use of the local available materials as substitutes for the imported and necessary materials for some of the practical application. For this reason this research aims at looking for the prospect of used locally available aggregate such as crushed clay bricks for the aim of producing proper concrete with suitable thermal and mechanical properties. Experimental investigations have been carried out to asses the effect of partial replacement of coarse aggregate by free manually crushed Brick with percentages (10, 20, 30 and 40% of virgin coarse aggregate in concrete mix for highway rigid pavement. While the percentage (0% replacement represent reference mix. Mix proportion based on the target of compressive strength for all replacement percentage of (33 MPa at (28 days to achieve AASHTO requirement for highway concrete rigid pavement .The results of flexural strength, modulus of elasticity, density and thermal conductivity refers to better performance (less thickness of concrete layer with large spacing between contraction or expansion joints and less stresses due to warping induced concrete layer for concrete mix with 20% crushed brick as replacement of coarse aggregate.

  20. Experimental study on the effect of volcanic residue on the performance of recycled lightweight aggregate concrete

    Science.gov (United States)

    Xiao, Li-guang; Li, Ji-heng; Liu, Qing-shun

    2017-08-01

    Recycled lightweight aggregate concrete prepared with waste brick recycled light aggregate has high water absorption, large apparent density and poor frost resistance. The technical measures of regen-erating lightweight aggregate concrete with modified waste bricks from volcanic slag are put forward. The effects of volcanic slag on the properties of waste lightweight aggregate concrete were studied. The experi-mental results show that volcanic slag can significantly reduce the apparent density of recycled lightweight aggregate concrete and improve its frost resistance.

  1. Mechanical Performance Evaluation of Self-Compacting Concrete with Fine and Coarse Recycled Aggregates from the Precast Industry.

    Science.gov (United States)

    Santos, Sara A; da Silva, Pedro R; de Brito, Jorge

    2017-08-04

    This paper intends to evaluate the feasibility of reintroducing recycled concrete aggregates in the precast industry. The mechanical properties of self-compacting concrete (SCC) with incorporation of recycled aggregates (RA) (coarse recycled aggregates (CRA) and fine recycled aggregates (FRA)) from crushed precast elements were evaluated. The goal was to evaluate the ability of producing SCC with a minimum pre-established performance in terms of mechanical strength, incorporating variable ratios of RA (FRA/CRA%: 0/0%, 25/25%, 50/50%, 0/100% and 100/0%) produced from precast source concretes with similar target performances. This replication in SCC was made for two strength classes (45 MPa and 65 MPa), with the intention of obtaining as final result concrete with recycled aggregates whose characteristics are compatible with those of a SCC with natural aggregates in terms of workability and mechanical strength. The results enabled conclusions to be established regarding the SCC's produced with fine and coarse recycled aggregates from the precast industry, based on its mechanical properties. The properties studied are strongly affected by the type and content of recycled aggregates. The potential demonstrated, mainly in the hardened state, by the joint use of fine and coarse recycled aggregate is emphasized.

  2. Neutron scattering techniques in the examination of recycled aggregate concrete

    International Nuclear Information System (INIS)

    Krezel, A.; Alabaster, P.; Bakshi, E.; McManus, K.

    1999-01-01

    Full text: Researchers at Swinburne University of Technology (SUT) have undertaken a research project aiming initially at better understanding the effects of any chemical impurities in Recycled Concrete Aggregate (RCA) on the microstructure development of Recycled Aggregate Concrete (RAC). Furthermore, a porosity of RCA and RAC and its effect on the acoustic performance and mechanical properties is being investigated. A number of conventional tests have been employed to examine the porosity of the aggregate and concrete made from RCA ranging from Volume of Permeable Voids test, through nitrogen adsorption to scanning electron microscopy. These tests are performed at SUT to characterise pores structure including pore size and volume as well as their surface area. The preparation of samples differs for the various tests, and this is a main reason contributing to inconsistencies in the results from these tests. None-the-less the results indicate strong positive correlation of inherent and purposely introduced porosity in RAC to its sound absorption capacities. Some inconsistency in the results is also due to the complexity of concrete itself compounded by the use of recycled material. However, the research has been granted a Grant from Australian Institute of Nuclear Science and Engineering (AINSE) which allows to conduct RAC examination using Small Angle Neutron Scattering (SANS). This neutron scattering technique characterises pore structure in a non-destructive manner. The results from this method should augment these obtained from conventional methods

  3. DURABILITY OF ASPHALT CONCRETE MIXTURES USING DOLOMITE AGGREGATES

    Directory of Open Access Journals (Sweden)

    Imad Al-Shalout

    2015-12-01

    Full Text Available This study deals with the durability of asphalt concrete, including the effects of different gradations, compaction temperatures and immersion time on the durability potential of mixtures. The specific objectives of this study are: to investigate the effect of compaction temperature on the mechanical properties of asphalt concrete mixtures; investigate the effect of bitumen content and different aggregate gradations on the durability potential of bituminous mixtures.

  4. Multi-factor Effects on the Durability of Recycle Aggregate Concrete

    Science.gov (United States)

    Ma, Huan; Cui, Yu-Li; Zhu, Wen-Yu; Xie, Xian-Jie

    2016-05-01

    Recycled Aggregate Concrete (RAC) was prepared with different recycled aggregate replacement ratio, 0, 30%, 70% and 100% respectively. The performances of RAC were examined by the freeze-thaw cycle, carbonization and sulfate attack to assess the durability. Results show that test sequence has different effects on the durability of RAC; the durability is poorer when carbonation experiment was carried out firstly, and then other experiment was carried out again; the durability is better when recycled aggregate replacement ratio is 70%.

  5. Evaluation of the use of steelmaking slag as an aggregate in concrete mix: A factorial design approach

    OpenAIRE

    Aljbour Salah H.; Tarawneh Sultan A.; Al-Harahsheh Adnan M.

    2017-01-01

    Slag is investigated towards its potential use as an aggregate in concrete mix production. Full factorial design methodology is applied to study the effect of two process input variables, namely: slag as coarse aggregate and slag as medium aggregate on the properties of concrete mix. Additionally, the interaction between input variables is also examined. Incorporating steel slag aggregate in the concrete mix affected its compressive strength. Enhanced compressive strength concrete mix was obt...

  6. Generation of urban road dust from anti-skid and asphalt concrete aggregates.

    Science.gov (United States)

    Tervahattu, Heikki; Kupiainen, Kaarle J; Räisänen, Mika; Mäkelä, Timo; Hillamo, Risto

    2006-04-30

    Road dust forms an important component of airborne particulate matter in urban areas. In many winter cities the use of anti-skid aggregates and studded tires enhance the generation of mineral particles. The abrasion particles dominate the PM10 during springtime when the material deposited in snow is resuspended. This paper summarizes the results from three test series performed in a test facility to assess the factors that affect the generation of abrasion components of road dust. Concentrations, mass size distribution and composition of the particles were studied. Over 90% of the particles were aluminosilicates from either anti-skid or asphalt concrete aggregates. Mineral particles were observed mainly in the PM10 fraction, the fine fraction being 12% and submicron size being 6% of PM10 mass. The PM10 concentrations increased as a function of the amount of anti-skid aggregate dispersed. The use of anti-skid aggregate increased substantially the amount of PM10 originated from the asphalt concrete. It was concluded that anti-skid aggregate grains contribute to pavement wear. The particle size distribution of the anti-skid aggregates had great impact on PM10 emissions which were additionally enhanced by studded tires, modal composition, and texture of anti-skid aggregates. The results emphasize the interaction of tires, anti-skid aggregate, and asphalt concrete pavement in the production of dust emissions. They all must be taken into account when measures to reduce road dust are considered. The winter maintenance and springtime cleaning must be performed properly with methods which are efficient in reducing PM10 dust.

  7. A Factorial Design Approach to Analyse the Effect of Coarse Recycled Concrete Aggregates on the Properties of Hot Mix Asphalt

    Science.gov (United States)

    Tanty, Kiranbala; Mukharjee, Bibhuti Bhusan; Das, Sudhanshu Shekhar

    2018-02-01

    The present study investigates the effect of replacement of coarse fraction of natural aggregates by recycled concrete aggregates on the properties of hot mix asphalt (HMA) using general factorial design approach. For this two factors i.e. recycled coarse aggregates percentage [RCA (%)] and bitumen content percentage [BC (%)] are considered. Tests have been carried out on the HMA type bituminous concrete, prepared with varying RCA (%) and BC (%). Analysis of variance has been performed on the experimental data to determine the effect of the chosen factors on various parameters such as stability, flow, air void, void mineral aggregate, void filled with bitumen and bulk density. The study depicts that RCA (%) and BC (%) have significant effect on the selected responses as p value is less than the chosen significance level. In addition to above, the outcomes of the statistical analysis indicate that interaction between factors have significant effects on void mineral aggregate and bulk density of bituminous concrete.

  8. A Factorial Design Approach to Analyse the Effect of Coarse Recycled Concrete Aggregates on the Properties of Hot Mix Asphalt

    Science.gov (United States)

    Tanty, Kiranbala; Mukharjee, Bibhuti Bhusan; Das, Sudhanshu Shekhar

    2018-06-01

    The present study investigates the effect of replacement of coarse fraction of natural aggregates by recycled concrete aggregates on the properties of hot mix asphalt (HMA) using general factorial design approach. For this two factors i.e. recycled coarse aggregates percentage [RCA (%)] and bitumen content percentage [BC (%)] are considered. Tests have been carried out on the HMA type bituminous concrete, prepared with varying RCA (%) and BC (%). Analysis of variance has been performed on the experimental data to determine the effect of the chosen factors on various parameters such as stability, flow, air void, void mineral aggregate, void filled with bitumen and bulk density. The study depicts that RCA (%) and BC (%) have significant effect on the selected responses as p value is less than the chosen significance level. In addition to above, the outcomes of the statistical analysis indicate that interaction between factors have significant effects on void mineral aggregate and bulk density of bituminous concrete.

  9. Effect of the aggregate grading on the concrete air permeability

    Directory of Open Access Journals (Sweden)

    Argiz, C.

    2014-09-01

    Full Text Available Great durability problems are being found in concrete structures related to the penetrability of aggressive agents through the concrete (ie. chloride penetration, sulphate attack, carbonation, freezing and thawing, and so on. Air permeability coefficient is used as an effective tool to estimate the potential durability of concrete structures due to its direct relation with the microstructure and the moisture content. This paper discusses the effect of the aggregate grading and water/cement ratio on the air permeability coefficient. An aggregate grading with more sand than coarse aggregates has resulted more beneficial from the point of view of concrete air permeability. This fact can be attributed to a denser skeleton formed by the finer aggregates. With fine aggregates, the higher water/cement ratio, the lower air permeability. However, the contrary was found with coarse aggregates. Overall, a temperature increase from 20 °C to 60 °C during preconditioning led to a Dair increase of 40–80%.Se han encontrado una gran cantidad de problemas de durabilidad de estructuras de hormigón relacionados con la penetración de agentes agresivos externos (es decir, penetración de cloruros, ataque por sulfatos, carbonatación, hielo-deshielo, etc.. El coeficiente de permeabilidad al aire se utiliza como una herramienta eficaz para estimar la durabilidad potencial de las estructuras de hormigón debido a su relación directa con su microestructura y contenido de humedad. Se discute el efecto de la gradación de los áridos y relación agua/cemento en el coeficiente de permeabilidad al aire. Con áridos más finos que gruesos, el resultado es más beneficioso, lo que se atribuye a que la arena forma un esqueleto más denso. Con áridos más finos, al aumentar la relación agua/cemento, disminuye la permeabilidad al aire; pero con áridos más gruesos se ha observado lo contrario. Cuando se pre-acondiciona de 20 °C a 60 °C, se produce un aumento del Dair

  10. Influence of Aggregate Coated with Modified Sulfur on the Properties of Cement Concrete

    Directory of Open Access Journals (Sweden)

    Swoo-Heon Lee

    2014-06-01

    Full Text Available This paper proposes the mixing design of concrete having modified sulfur-coated aggregate (MSCA to enhance the durability of Portland cement concrete. The mechanical properties and durability of the proposed MSCA concrete were evaluated experimentally. Melting-modified sulfur was mixed with aggregate in order to coat the aggregate surface at a speed of 20 rpm for 120 s. The MSCA with modified sulfur corresponding to 5% of the cement weight did not significantly affect the flexural strength in a prism concrete beam specimen, regardless of the water-cement ratio (W/C. However, a dosage of more than 7.5% decreased the flexural strength. On the other hand, the MSCA considerably improved the resistance to the sulfuric acid and the freezing-thawing, regardless of the sulfur dosage in the MSCA. The coating modified sulfur of 5% dosage consequently led to good results for the mechanical properties and durability of MSCA concrete.

  11. Role of alkalis of aggregate origin in the deterioration of CAC concrete

    International Nuclear Information System (INIS)

    Blanco-Varela, M.T.; Martinez-Ramirez, S.; Vazquez, T.; Sanchez-Moral, S.

    2005-01-01

    Both hexagonal and cubic calcium aluminate cement (CAC) hydrates react with atmospheric CO 2 , bringing about mineralogical changes in concrete, which may, on occasion, lead to loss of mechanical strength. Alkaline hydrolysis or carbonation in the presence of alkalis is a highly destructive process. The purpose of the study was to determine what caused CAC concrete deterioration in a prestressed beam that had suffered intense external damage and showed signs of alkaline hydrolysis or a reaction between the aggregate and the cement. Samples of the internal (sound) and external (damaged) parts of the concrete were studied using XRF, XRD, FTIR, OM, SEM/EDX, and BSE techniques, and mechanical strength was measured on microspecimens extracted from both zones. The conclusion drawn from these analyses was that alkaline hydrolysis took place on or near the surface of the concrete. The white deposits observed around the alkali-containing aggregate were found to consist primarily of bayerite whose very loose consistency undermined the aggregate-matrix bond, greatly weakening the material

  12. Properties of lightweight aggregate concrete prepared with PVC granules derived from scraped PVC pipes.

    Science.gov (United States)

    Kou, S C; Lee, G; Poon, C S; Lai, W L

    2009-02-01

    This paper aims to investigate the fresh and hardened properties of lightweight aggregate concretes that are prepared with the use of recycled plastic waste sourced from scraped PVC pipes to replace river sand as fine aggregates. A number of laboratory prepared concrete mixes were tested, in which river sand was partially replaced by PVC plastic waste granules in percentages of 0%, 5%, 15%, 30% and 45% by volume. Two major findings are identified. The positive side shows that the concrete prepared with a partial replacement by PVC was lighter (lower density), was more ductile (greater Poisson's ratios and reduced modulus of elasticity), and had lower drying shrinkage and higher resistance to chloride ion penetration. The negative side reveals that the workability, compressive strength and tensile splitting strength of the concretes were reduced. The results gathered would form a part of useful information for recycling PVC plastic waste in lightweight concrete mixes.

  13. Stress wave communication in concrete: I. Characterization of a smart aggregate based concrete channel

    International Nuclear Information System (INIS)

    Siu, Sam; Wu, Wenhao; Zhi Ding; Ji, Qing; Song, Gangbing

    2014-01-01

    In this paper, we explore the characteristics of a concrete block as a communication medium with piezoelectric transducers. Lead zirconate titanate (PZT) is a piezoceramic material used in smart materials intended for structural health monitoring (SHM). Additionally, a PZT based smart aggregate (SA) is capable of implementing stress wave communications which is utilized for investigating the properties of an SA based concrete channel. Our experiments characterize single-input single-output and multiple-input multiple-output (MIMO) concrete channels in order to determine the potential capacity limits of SAs for stress wave communication. We first provide estimates and validate the concrete channel response. Followed by a theoretical upper bound for data rate capacity of our two channels, demonstrating a near-twofold increase in channel capacity by utilizing multiple transceivers to form an MIMO system. Our channel modeling techniques and results are also helpful to researchers using SAs with regards to SHM, energy harvesting and stress wave communications. (paper)

  14. Environmental suitability of recycled concrete aggregate in highways.

    Science.gov (United States)

    2015-01-01

    The use of recycled concrete aggregate materials in highway constructions as compared to the use of virgin : materials reduces virgin natural resource demands on the environment. In order to evaluate their potential use of : recycle materials in high...

  15. Mechanical and Microstructural Evaluations of Lightweight Aggregate Geopolymer Concrete before and after Exposed to Elevated Temperatures.

    Science.gov (United States)

    Abdulkareem, Omar A; Abdullah, Mohd Mustafa Al Bakri; Hussin, Kamarudin; Ismail, Khairul Nizar; Binhussain, Mohammed

    2013-10-09

    This paper presents the mechanical and microstructural characteristics of a lightweight aggregate geopolymer concrete (LWAGC) synthesized by the alkali-activation of a fly ash source (FA) before and after being exposed to elevated temperatures, ranging from 100 to 800 °C. The results show that the LWAGC unexposed to the elevated temperatures possesses a good strength-to-weight ratio compared with other LWAGCs available in the published literature. The unexposed LWAGC also shows an excellent strength development versus aging times, up to 365 days. For the exposed LWAGC to the elevated temperatures of 100 to 800 °C, the results illustrate that the concretes gain compressive strength after being exposed to elevated temperatures of 100, 200 and 300 °C. Afterward, the strength of the LWAGC started to deteriorate and decrease after being exposed to elevated temperatures of 400 °C, and up to 800 °C. Based on the mechanical strength results of the exposed LWAGCs to elevated temperatures of 100 °C to 800 °C, the relationship between the exposure temperature and the obtained residual compressive strength is statistically analyzed and achieved. In addition, the microstructure investigation of the unexposed LWAGC shows a good bonding between aggregate and mortar at the interface transition zone (ITZ). However, this bonding is subjected to deterioration as the LWAGC is exposed to elevated temperatures of 400, 600 and 800 °C by increasing the microcrack content and swelling of the unreacted silicates.

  16. Durability and Shrinkage Characteristics of Self-Compacting Concretes Containing Recycled Coarse and/or Fine Aggregates

    Directory of Open Access Journals (Sweden)

    Mehmet Gesoglu

    2015-01-01

    Full Text Available This paper addresses durability and shrinkage performance of the self-compacting concretes (SCCs in which natural coarse aggregate (NCA and/or natural fine aggregate (NFA were replaced by recycled coarse aggregate (RCA and/or recycled fine aggregate (RFA, respectively. A total of 16 SCCs were produced and classified into four series, each of which included four mixes designed with two water to binder (w/b ratios of 0.3 and 0.43 and two silica fume replacement levels of 0 and 10%. Durability properties of SCCs were tested for rapid chloride penetration, water sorptivity, gas permeability, and water permeability at 56 days. Also, drying shrinkage accompanied by the water loss and restrained shrinkage of SCCs were monitored over 56 days of drying period. Test results revealed that incorporating recycled coarse and/or fine aggregates aggravated the durability properties of SCCs tested in this study. The drying shrinkage and restrained shrinkage cracking of recycled aggregate (RA concretes had significantly poorer performance than natural aggregate (NA concretes. The time of cracking greatly prolonged as the RAs were used along with the increase in water/binder ratio.

  17. Utilising Fine and Coarse Recycled Aggregates from the Gulf Region in Concrete

    Science.gov (United States)

    Jones, M. Rod; Halliday, Judith E.; Csetenyi, Laszlo; Zheng, Li; Strompinis, N.

    This paper explores the feasibility in utilising materials generated from C&DW to produce a `green' concrete. The two materials that are considered here are, (i) up-sizing silt-size material generated from recycled aggregates to produce a synthetic silt-sand and (ii) processed recycled coarse aggregates (RA) sourced from a Gulf Region landfill site. The work has demonstrated that there is potential for utilising silt wastes into foamed concrete, which can then be crushed to a sand-sized material suitable for use in concrete, however the porous nature of the material has highlighted that the water demand of this RA is high. RAs were characterised to BS EN 12620 and found suitable for use in concrete. The effect of RA on concrete properties is minimal when used up to 35% replacement levels, provided that they are pre-soaked.

  18. DURABILITY OF GREEN CONCRETE WITH TERNARY CEMENTITIOUS SYSTEM CONTAINING RECYCLED AGGREGATE CONCRETE AND TIRE RUBBER WASTES

    Directory of Open Access Journals (Sweden)

    MAJID MATOUQ ASSAS

    2016-06-01

    Full Text Available All over the world billions of tires are being discarded and buried representing a serious ecological threat. Up to now a small part is recycled and millions of tires are just stockpiled, landfilled or buried. This paper presents results about the properties and the durability of green concrete contains recycled concrete as a coarse aggregate with partial replacement of sand by tire rubber wastes for pavement use. Ternary cementious system, Silica fume, Fly ash and Cement Kiln Dust are used as partial replacement of cement by weight. Each one replaced 10% of cement weight to give a total replacement of 30%. The durability performance was assessed by means of water absorption, chloride ion permeability at 28 and 90 days, and resistance to sulphuric acid attack at 1, 7, 14 and 28 days. Also to the compression behaviors for the tested specimens at 7, 14, 28 and 90 days were detected. The results show the existence of ternary cementitious system, silica fly ash and Cement Kiln Dust minimizes the strength loss associated to the use of rubber waste. In this way, up to 10% rubber content and 30% ternary cementious system an adequate strength class value (30 MPa, as required for a wide range of common structural uses, can be reached both through natural aggregate concrete and recycled aggregate concrete. Results also show that, it is possible to use rubber waste up to 15% and still maintain a high resistance to acid attack. The mixes with 10%silica fume, 10% fly ash and 10% Cement Kiln Dust show a higher resistance to sulphuric acid attack than the reference mix independently of the rubber waste content. The mixes with rubber waste and ternary cementious system was a lower resistance to sulphuric acid attack than the reference mix.

  19. The Utilisation of Shredded PET as Aggregate Replacement for Interlocking Concrete Block

    Science.gov (United States)

    Mokhtar, M.; Kaamin, M.; Sahat, S.; Hamid, N. B.

    2018-03-01

    The consumption of plastic has grown substantially all over the world in recent years and this has created huge quantities of plastic-based waste. Plastic waste is now a serious environmental threat to the modern way of living, although steps were taken to reduce its consumption. This creates substantial garbage every day, which is much unhealthy. Plastic bottles such as Polyethylene terephthalate (PET) was use as the partially component in this making of interlocking blocks concrete. This project investigates the strength and workability of the interlocking block concrete by replacing course aggregate with % PET. The suitability of recycled plastics (PET) as course aggregate in interlocking block concrete and its advantages are discussed here. Moreover, there were more benefits when using interlocking block than using conventional block such as it easy for construction because they are aligning, easy to place, high speed stacking and they offer more resistance to shear and buildings would be even stronger. Based on the test perform, the failure parameter were discussed .From the compressive strength test result, it shows that the strength of concrete block decreased with increased of PET used. From the results, it shows that higher compressive strength was found with 5% natural course aggregate replaced with PET compared to other percentages.

  20. Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content.

    Science.gov (United States)

    López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

    2016-01-26

    In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m³ of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m³ of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works.

  1. Effect of Coating Palm Oil Clinker Aggregate on the Engineering Properties of Normal Grade Concrete

    Directory of Open Access Journals (Sweden)

    Fuad Abutaha

    2017-10-01

    Full Text Available Palm oil clinker (POC is a waste material generated in large quantities from the palm oil industry. POC, when crushed, possesses the potential to serve as an aggregate for concrete production. Experimental investigation on the engineering properties of concrete incorporating POC as aggregate and filler material was carried out in this study. POC was partially and fully used to replace natural coarse aggregate. The volumetric replacements used were 0%, 20%, 40%, 60%, 80%, and 100%. POC, being highly porous, negatively affected the fresh and hardened concrete properties. Therefore, the particle-packing (PP method was adopted to measure the surface and inner voids of POC coarse aggregate in the mixtures at different substitution levels. In order to enhance the engineering properties of the POC concrete, palm oil clinker powder (POCP was used as a filler material to fill up and coat the surface voids of POC coarse, while the rest of the mix constituents were left as the same. Fresh and hardened properties of the POC concrete with and without coating were determined, and the results were compared with the control concrete. The results revealed that coating the surface voids of POC coarse with POCP significantly improved the engineering properties as well as the durability performance of the POC concrete. Furthermore, using POC as an aggregate and filler material may reduce the continuous exploitation of aggregates from primary sources. Also, this approach offers an environmental friendly solution to the ongoing waste problems associated with palm oil waste material.

  2. Aggregate Effect on the Concrete Cone Capacity of an Undercut Anchor under Quasi-Static Tensile Load.

    Science.gov (United States)

    Marcon, Marco; Ninčević, Krešimir; Boumakis, Ioannis; Czernuschka, Lisa-Marie; Wan-Wendner, Roman

    2018-05-01

    In the last decades, fastening systems have become an essential part of the construction industry. Post-installed mechanical anchors are frequently used in concrete members to connect them with other load bearing structural members, or to attach appliances. Their performance is limited by the concrete related failure modes which are highly influenced by the concrete mix design. This paper aims at investigating the effect that different aggregates used in the concrete mix have on the capacity of an undercut anchor under tensile quasi-static loading. Three concrete batches were cast utilising three different aggregate types. For two concrete ages (28 and 70 days), anchor tensile capacity and concrete properties were obtained. Concrete compressive strength, fracture energy and elastic modulus are used to normalize and compare the undercut anchor concrete tensile capacity employing some of the most widely used prediction models. For a more insightful comparison, a statistical method that yields also scatter information is introduced. Finally, the height and shape of the concrete cones are compared by highly precise and objective photogrammetric means.

  3. Evaluation of water transfer from saturated lightweight aggregate to cement paste matrix by neutron radiography

    International Nuclear Information System (INIS)

    Maruyama, I.; Kanematsu, M.; Noguchi, T.; Iikura, H.; Teramoto, A.; Hayano, H.

    2009-01-01

    In high-strength concrete with low water-cement ratio, self-desiccation occurs due to cement hydration and causes shrinkage and an increased risk of cracking. While high-strength concrete has a denser matrix than normal-strength concrete, resulting in lower permeability, early-age cracks would cancel out this advantage. For the mitigation of this self-desiccation and resultant shrinkage, water-saturated porous aggregate, such as artificial lightweight aggregate, may be used in high-strength concrete. In this contribution, for the purpose of clarification of the volume change of high-strength concrete containing water-saturated lightweight aggregate, water transfer from the lightweight aggregate to cement paste matrix is visualized by neutron radiography. As a result, it is clear that water was supplied to the cement paste matrix in the range 3-8 mm from the surface of the aggregate, and the osmotic forces may yield water transfer around lightweight aggregate in a few hours after mixing.

  4. Experimental investigation on the properties of concrete containing post-consumer plastic waste as coarse aggregate replacement

    Directory of Open Access Journals (Sweden)

    Zasiah TAFHEEM

    2018-03-01

    Full Text Available The consumption of various forms of plastic has been increased in recent days due to the boost in industrialization and other human activities. Most of the plastic wastes are abandoned and require large landfill area for storage. More importantly, the low biodegradability of plastic poses a serious threat to environment protection issue. Various methods have been followed for the disposal of plastic in an attempt to reduce the negative impact of the plastic on the environment. Recently, various types of plastic have been incorporated in concrete to minimize the exposure of plastic to the environment. The aim of this study is to investigate the properties of concrete containing polyethylene terephthalate (PET, and high density polyethylene (HDPE plastic that were used as partial replacement of coarse aggregate (CA. In this study, four compositions of stone aggregate(S: plastic waste ratios have been used by volume basis: 100% S: 0% Plastic (control concrete, 90% S: 10% PET, 90% S: 10% HDPE, and 90% S: 5% PET+5% HDPE. The effects of waste plastic addition on the mechanical properties of concrete are presented in this paper. Test results reveal that minimum reduction in compressive strength has been found 35% in case of 10% PET plastic replaced concrete whereas splitting tensile strength for 10% PET replaced concrete has been increased by 21% while compared to control concrete. In addition, fresh unit weight of concrete containing plastic waste has been decreased by 4% in comparison to control concrete.

  5. Alteration of alkali reactive aggregates autoclaved in different alkali solutions and application to alkali-aggregate reaction in concrete (II) expansion and microstructure of concrete microbar

    International Nuclear Information System (INIS)

    Lu Duyou; Mei Laibao; Xu Zhongzi; Tang Mingshu; Mo Xiangyin; Fournier, Benoit

    2006-01-01

    The effect of the type of alkalis on the expansion behavior of concrete microbars containing typical aggregate with alkali-silica reactivity and alkali-carbonate reactivity was studied. The results verified that: (1) at the same molar concentration, sodium has the strongest contribution to expansion due to both ASR and ACR, followed by potassium and lithium; (2) sufficient LiOH can completely suppress expansion due to ASR whereas it can induce expansion due to ACR. It is possible to use the duplex effect of LiOH on ASR and ACR to clarify the ACR contribution when ASR and ACR may coexist. It has been shown that a small amount of dolomite in the fine-grained siliceous Spratt limestone, which has always been used as a reference aggregate for high alkali-silica reactivity, might dedolomitize in alkaline environment and contribute to the expansion. That is to say, Spratt limestone may exhibit both alkali-silica and alkali-carbonate reactivity, although alkali-silica reactivity is predominant. Microstructural study suggested that the mechanism in which lithium controls ASR expansion is mainly due to the favorable formation of lithium-containing less-expansive product around aggregate particles and the protection of the reactive aggregate from further attack by alkalis by the lithium-containing product layer

  6. Mechanical Properties of High Performance Concrete Containing Waste Plastic as Aggregate

    Directory of Open Access Journals (Sweden)

    Abdulkader Ismail Al-Hadithi

    2015-08-01

    Full Text Available The world's population growth and the increasing demand for new infrastructure facilities and buildings , present us with the vision of a higher resources consumption, specially in the form of more durable concrete such as High Performance Concrete (HPC . Moreover , the growth of the world pollution by plastic waste has been tremendous. The aim of this research is to investigate the change in mechanical properties of HPC with added waste plastics in concrete. For this purpose 2.5%, 5% and 7.5% in volume of natural fine aggregate in the HPC mixes were replaced by an equal volume of Polyethylene Terephthalate (PET waste , got by shredded PET bottles. The mechanical properties (compressive, splitting tensile, and flexural strength evaluated at the ages of (7 ,28, 56 and 91 days while the static modulus of elasticity tested at (28 and 91 days . The results indicated that HPC containing PET-aggregate presented lower compressive strength and static elasticity . The splitting strength displayed an arising trend at the initial stages, however, they have a tendency to decrease after a while. On the other hand, flexural strength results gave better modulus of rapture at all ages of curing , as compared with reference concrete specimens.

  7. Behavior of Low Grade Steel Fiber Reinforced Concrete Made with Fresh and Recycled Brick Aggregates

    Directory of Open Access Journals (Sweden)

    Md. Shariful Islam

    2017-01-01

    Full Text Available In recent years, recycled aggregates from construction and demolition waste (CDW have been widely accepted in construction sectors as the replacement of coarse aggregate in order to minimize the excessive use of natural resources. In this paper, an experimental investigation is carried out to observe the influence of low grade steel fiber reinforcements on the stress-strain behavior of concrete made with recycled and fresh brick aggregates. In addition, compressive strength by destructive and nondestructive tests, splitting tensile strength, and Young’s modulus are determined. Hooked end steel wires with 50 mm of length and an aspect ratio of 55.6 are used as fiber reinforcements in a volume fraction of 0% (control case, 0.50%, and 1.00% in concrete mixes. The same gradation of aggregates and water-cement ratio (w/c=0.44 were used to assess the effect of steel fiber in all these concrete mixes. All tests were conducted at 7, 14, and 28 days to perceive the effect of age on different mechanical properties. The experimental results show that around 10%~15% and 40%~60% increase in 28 days compressive strength and tensile strength of steel fiber reinforced concrete, respectively, compared to those of the control case. It is observed that the effect of addition of 1% fiber on the concrete compressive strength is little compared to that of 0.5% steel fiber addition. On the other hand, strain of concrete at failure of steel fiber reinforced concrete has increased almost twice compared to the control case. A simple analytical model is also proposed to generate the ascending portions of the stress-strain curve of concrete. There exists a good correlation between the experimental results and the analytical model. A relatively ductile failure is observed for the concrete made with low grade steel fibers.

  8. Properties of Non-Structural Concrete Made with Mixed Recycled Aggregates and Low Cement Content

    Science.gov (United States)

    López-Uceda, Antonio; Ayuso, Jesús; López, Martin; Jimenez, José Ramón; Agrela, Francisco; Sierra, María José

    2016-01-01

    In spite of not being legally accepted in most countries, mixed recycled aggregates (MRA) could be a suitable raw material for concrete manufacturing. The aims of this research were as follows: (i) to analyze the effect of the replacement ratio of natural coarse aggregates with MRA, the amount of ceramic particles in MRA, and the amount of cement, on the mechanical and physical properties of a non-structural concrete made with a low cement content; and (ii) to verify if it is possible to achieve a low-strength concrete that replaces a greater amount of natural aggregate with MRA and that has a low cement content. Two series of concrete mixes were manufactured using 180 and 200 kg/m3 of CEM II/A-V 42.5 R type Portland cement. Each series included seven concrete mixes: one with natural aggregates; two MRA with different ceramic particle contents; and one for each coarse aggregate replacement ratio (20%, 40%, and 100%). To study their properties, compressive and splitting tensile strength, modulus of elasticity, density, porosity, water penetration, and sorptivity, tests were performed. The results confirmed that the main factors affecting the properties analyzed in this research are the amount of cement and the replacement ratio; the two MRAs used in this work presented a similar influence on the properties. A non-structural, low-strength concrete (15 MPa) with an MRA replacement ratio of up to 100% for 200 kg/m3 of cement was obtained. This type of concrete could be applied in the construction of ditches, sidewalks, and other similar civil works. PMID:28787874

  9. AN EXPERIMENTAL STUDY ON BEHAVIOUR OF RECYCLED AGGREGATE CONCRETE WITH GROUND GRANULATED BLAST FURNACE SLAG FLYASH

    OpenAIRE

    B.Sasikala*, K.Shanthi, B.Jose RavindraRaj

    2017-01-01

    Concrete is the single largest manufactured material in the world . The use of recycled materials in construction is an issue of great importance. Utilization of Recycled Aggregates (RA), Ground Granulated Blast Furnace Slag (GGBFS) and fly ash in concrete addresses this issue. In this project, strength, durability of Recycled Aggregate Concrete (RAC) with GGBFS was studied. M-50 grade concrete with 0.30 w/c ratio and maximum size of 16mm course aggregate was used for this study. Totally 16 m...

  10. Applicability assessment of concrete with recycled coarse aggregates in Havana, Cuba

    Directory of Open Access Journals (Sweden)

    Pavón, E.

    2012-09-01

    Full Text Available The recent viability studies carried out in Havana, Cuba, according to natural or recycled aggregates, exhibited high volume production of construction and demolition waste (CDW. The last well-known data of concrete waste generation reached to 1800 m3/month. This situation, together with the depletion of the quarry aggregates closed to the capital, requires the use of such debris as aggregate for concrete production. In this work, four origin recycled concrete aggregates (RCA were produced and characterized. Recycled aggregate concrete with 25%, 50% and 100% of RCA and 0.45, 0.50 and 0.55 of water-cement ratio were produced. Physical, mechanical and durabilidty properties of thoses concretes were determined and evaluated, and their applicability as structural material in different aggressive environments according to Cuban normative was defined.Los estudios de viabilidad realizados recientemente en La Habana, Cuba muestran elevadas cifras de producción de residuos de construcción y demolición (RCD. Los últimos datos conocidos de generación de escombros de hormigón alcanzan valores cercanos a los 1800m3/mensual. Esta situación unida al agotamiento de los áridos en las zonas cercanas a la capital hace necesaria la utilización de estos escombros como áridos en la fabricación de hormigones. En el trabajo realizado se trituraron escombros de hormigón de cuatro orígenes diferentes, después de su caracterización se fabricaron hormigones con 25%, 50% y 100% de árido reciclado y con relaciones agua-cemento de 0.45, 0.50 y 0.55. A partir de la evaluación de las propiedades físico-mecánicas y de durabilidad obtenidas por los hormigones reciclados, se define la aplicabilidad de los mismos como hormigón estructural para ser utilizados en los diferentes tipos de ambientes de agresividad que tiene definido la normativa cubana.

  11. Permeability of Concrete with Recycled Concrete Aggregate and Pozzolanic Materials under Stress.

    Science.gov (United States)

    Wang, Hailong; Sun, Xiaoyan; Wang, Junjie; Monteiro, Paulo J M

    2016-03-30

    The research reported herein studied the permeability of concrete containing recycled-concrete aggregate (RA), superfine phosphorous slag (PHS), and ground granulated blast-furnace slag (GGBS) with and without stress. Test results showed that the chloride diffusion coefficient of RA concrete (RAC) without external loads decreased with time, and the permeability of RAC is much lower than that of the reference concrete due to the on-going hydration and the pozzolanic reaction provided by the PHS and GGBS additives in the RAC mixture. The permeability of chloride under flexural load is much more sensitive than that under compressive load due to the differences in porosity and cracking pattern. At low compressive stress levels, the permeability of chloride decreased by the closing of pores and microcracks within RAC specimens. However, in a relatively short time the chloride diffusion coefficient and the chloride content increased rapidly with the increase of compressive stress when it exceeded a threshold stress level of approximate 35% of the ultimate compressive strength. Under flexural stress, the chloride transport capability increased with the increase of stress level and time. At high compressive and flexural stress levels, creep had a significant effect on the permeability of chloride in the RAC specimens due to the damage from the nucleation and propagation of microcracks over time. It is apparent that mortar cracking has more of a significant effect on the chloride transport in concrete than cracking in the interfacial transition zone (ITZ).

  12. Experimental Investigation on Damping Property of Coarse Aggregate Replaced Rubber Concrete

    Science.gov (United States)

    Sugapriya, P.; Ramkrishnan, R.; Keerthana, G.; Saravanamurugan, S.

    2018-02-01

    Rubber has good damping and vibrational characteristics and can reduce cracking significantly due to its elastic nature. This property of rubber can be incorporated in concrete to control vibrations and create better pavements. Crumb Rubber on being dumped in landfills has serious repercussions and causes soil and land pollution. An innovative use of waste tires is shredding them into small pieces and using them as a replacement for coarse aggregate. Crumb rubber is obtained by chopping scrap tires, and in this study it was added in two different sets named SET 1 - Treated Crumb Rubber and concrete, and SET 2 - Treated Crumb rubber with Ultra Fine GGBS as admixture in concrete. Coarse aggregate replaces Rubber in each of the 2 SET’s in proportions of 5, 10, 15 and 20%. Properties like Compressive Strength, Young’s Modulus, Direct and Semi direct Ultrasonic Pulse Velocity, Sorptivity, Damping ratio and Frequency were found out. Deformation and mode shape were studied with modal analysis and static analysis by applying a uniform pressure corresponding to the highest compressive strength of the slab, using ANSYS.

  13. Research on test of alkali-resistant glass fibre enhanced seawater coral aggregate concrete

    Science.gov (United States)

    Liu, Leiyang; Wang, Xingquan

    2017-12-01

    It is proposed in the 13th five-year plan that reefs of the south China sea should be constructed. In the paper, an innovative thinking was proposed for the first time in order to realize local material acquisition in island construction and life dependence on sea, namely alkali-resistant glass fibre is mixed in coralaggregate concrete as reinforcing material. The glass fibre is characterized by low price, low hardness, good dispersibility and convenient construction. Reliable guarantee is provided for widely applying the material in future projects. In the paper, an orthogonal test method is firstly applied to determine the mix proportion of grade C50 coral aggregate concrete. Then, the design plan ofmix proportion of alkali-resistant glass fibre enhanced seawater coral aggregate concrete is determined. Finally, the influence law of alkali-resistant glass fibre dosageon tensile compressiveflexture strength of seawatercoralaggregate concrete is made clear.

  14. ALKALI AGGREGATE REACTIONS IN CONCRETE: A REVIEW OF ...

    African Journals Online (AJOL)

    coarse aggregate, water and chemical admixtures to improve its various .... slowly from certai~ alkali-bearing rock components within the ... retaining walls. ... expand in pores and microcracks of the cementious matrix. ... allY'a' pressure on the surrounding concrete ... effect is reduced structural integrity and shortened.

  15. The use of a concrete additive to eliminate returned concrete waste volumes

    Directory of Open Access Journals (Sweden)

    Bester Johannes

    2017-01-01

    Full Text Available This paper investigates the effects of the use of a recently developed two-component powdered product made from polymers and inorganic compounds that can be mechanically mixed into returned fresh ready-mix concrete to allow for the separation of the concrete into fine and coarse aggregates. This allows for the re-use of the returned concrete as aggregates in the manufacturing of new concrete. The returned concrete waste can therefore be eliminated, thus reducing virgin aggregate usage, as well as reducing the environmental impact of returned concrete. In this study, the treated recycled fresh concrete was separated into fine and coarse aggregates, and then used at replacement levels of 0%, 25%, 50%, 75% and 100%. The effect of the product on the material classification, and on important fresh and hardened properties of the concrete for the above-mentioned replacement values was tested. For the fine aggregate, the results indicate minimal changes in both the fresh and hardened properties. For the coarse aggregate, the results show a marked improvement of flexural strength with an increase in replacement value when coarse aggregates are used. Very high replacement levels may be used with very little effect on the quality of the new concrete.

  16. Feasibility of reclaimed asphalt pavement as aggregate in portland cement concrete pavements.

    Science.gov (United States)

    2013-11-01

    This research effort was focused on evaluating the feasibility of using minimally processed reclaimed : asphalt pavement (RAP) as aggregate replacement in concrete pavements. This research demonstrated : that concretes with up to 50 percent of the fi...

  17. Cyclic behavior of low rise concrete shear walls containing recycled coarse and fine aggregates

    NARCIS (Netherlands)

    Qiao, Qiyun; Cao, Wanlin; Qian, Zhiwei; Li, Xiangyu; Zhang, Wenwen; Liu, Wenchao

    2017-01-01

    In this study, the cyclic behaviors of low rise concrete shear walls using recycled coarse or fine aggregates were investigated. Eight low rise Recycled Aggregates Concrete (RAC) shear wall specimens were designed and tested under a cyclic loading. The following parameters were varied:

  18. Multi-functional smart aggregate-based structural health monitoring of circular reinforced concrete columns subjected to seismic excitations

    International Nuclear Information System (INIS)

    Gu, Haichang; Song, Gangbing; Moslehy, Yashar; Mo, Y L; Sanders, David

    2010-01-01

    In this paper, a recently developed multi-functional piezoceramic-based device, named the smart aggregate, is used for the health monitoring of concrete columns subjected to shake table excitations. Two circular reinforced concrete columns instrumented with smart aggregates were fabricated and tested with a recorded seismic excitation at the structural laboratory at the University of Nevada—Reno. In the tests, the smart aggregates were used to perform multiple monitoring functions that included dynamic seismic response detection, structural health monitoring and white noise response detection. In the proposed health monitoring approach, a damage index was developed on the basis of the comparison of the transfer function with the baseline function obtained in the healthy state. A sensor-history damage index matrix is developed to monitor the damage evolution process. Experimental results showed that the acceleration level can be evaluated from the amplitude of the dynamic seismic response; the damage statuses at different locations were evaluated using a damage index matrix; the first modal frequency obtained from the white noise response decreased with increase of the damage severity. The proposed multi-functional smart aggregates have great potential for use in the structural health monitoring of large-scale concrete structures

  19. Patterns of gravity induced aggregate migration during casting of fluid concretes

    Energy Technology Data Exchange (ETDEWEB)

    Spangenberg, J. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Roussel, N., E-mail: Nicolas.roussel@lcpc.fr [Universite Paris Est, Laboratoire Central des Ponts et Chaussees (LCPC) (France); Hattel, J.H. [Department of Mechanical Engineering, Technical University of Denmark (DTU) (Denmark); Sarmiento, E.V.; Zirgulis, G. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Geiker, M.R. [Department of Structural Engineering, Norwegian University of Science and Technology (NTNU) (Norway); Department of Civil Engineering, Technical University of Denmark (DTU) (Denmark)

    2012-12-15

    In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.

  20. Patterns of gravity induced aggregate migration during casting of fluid concretes

    International Nuclear Information System (INIS)

    Spangenberg, J.; Roussel, N.; Hattel, J.H.; Sarmiento, E.V.; Zirgulis, G.; Geiker, M.R.

    2012-01-01

    In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in a decrease of coarse aggregates volume fraction with the horizontal distance from the pouring point and in a puzzling vertical multi-layer structure. The origin of this multi layer structure is discussed and analyzed with the help of numerical simulations of free surface flow. Our results suggest that it finds its origin in the non Newtonian nature of fresh concrete and that increasing casting rate shall decrease the magnitude of gravity induced particle migration.

  1. Mix design and properties of fly ash waste lightweight aggregates in structural lightweight concrete

    OpenAIRE

    Manu S. Nadesan; P. Dinakar

    2017-01-01

    Concrete is one of the most widely used construction materials and has the ability to consume industrial wastes in high volume. As the demand for concrete is increasing, one of the effective ways to reduce the undesirable environmental impact of the concrete is by the use of waste and by-product materials as cement and aggregate substitutes in concrete. One such waste material is fly ash, which is produced in large quantities from thermal power plants as a by-product. A substantial amount of ...

  2. Effects of Elevated Temperature on Concrete with Recycled Coarse Aggregates

    Science.gov (United States)

    Salau, M. A.; Oseafiana, O. J.; Oyegoke, T. O.

    2015-11-01

    This paper discusses the effects of heating temperatures of 200°C, 400°C and 600°C each for 2 hours at a heating rate of 2.5°C/min on concrete with the content of Natural Coarse Aggregates (NCA) partially replaced with Recycled Coarse Aggregates (RCA), obtained from demolished building in the ratio of 0%, 15% and 30%.There was an initial drop in strength from 100°C to 200°C which is suspected to be due to the relatively weak interfacial bond between the RCA and the hardened paste within the concrete matrix;a gradual increase in strength continued from 200°C to 450°C and steady drop occurred again as it approached 600°C.With replacement proportion of 0%, 15% and 30% of NCA and exposure to peak temperature of 600°C, a relative concrete strength of 23.6MPa, 25.3MPa and 22.2MPa respectively can be achieved for 28 days curing age. Furthermore, RAC with 15% NCA replacement when exposed to optimum temperature of 450°C yielded high compressive strength comparable to that of control specimen (normal concrete). In addition, for all concrete samples only slight surface hairline cracks were noticed as the temperature approached 400°C. Thus, the RAC demonstrated behavior just like normal concrete and may be considered fit for structural use.

  3. Evaluating the Carbonation Resistance of Self Compacting Concrete made with Recycled Concrete Aggregates

    Directory of Open Access Journals (Sweden)

    S P Singh

    2016-07-01

    Full Text Available The paper presents the results of an investigation conducted to examine carbonation resistance of Self Compacting Concrete (SCC made with coarse Recycled Concrete Aggregates (RCA. In total, five SCC mixes were prepared by systematically replacing coarse Natural Aggregates (NA by RCA at 0, 25, 50, 75 and 100%. In order to measure the carbonation resistance of SCC made with RCA, accelerated carbonation tests were performed for 4 and 12 weeks of exposure to carbon dioxide. The carbonation resistance has been evaluated after curing periods of 28 and 90 days. In addition to this, the compressive strength of all the mixes was also obtained after 7, 28 and 90 days of curing and ultra-sonic pulse velocity tests (UPV were also conducted. The results indicate that with the increase in the content of RCA as replacement of NA, decrease in the carbonation resistance, compressive strength and UPV was observed for all SCC mixes. It has been observed that the SCC mixes containing low percentages of RCA (i.e. 25% as replacement of NA do not impart detrimental behaviour in the overall performance but higher replacement levels (>50% have been found to deteriorate the performance in terms of carbonation resistance, compressive strength and UPV.

  4. Patterns of gravity induced aggregate migration during casting of fluid concretes

    DEFF Research Database (Denmark)

    Spangenberg, Jon; Roussel, N.; Hattel, Jesper Henri

    2012-01-01

    In this paper, aggregate migration patterns during fluid concrete castings are studied through experiments, dimensionless approach and numerical modeling. The experimental results obtained on two beams show that gravity induced migration is primarily affecting the coarsest aggregates resulting in...

  5. Study on Characteristics of Lightweight Aggregate Concrete Made From Foam and Ordinary Portland Cement

    Directory of Open Access Journals (Sweden)

    Ibrahim N.M.

    2016-01-01

    Full Text Available The production and characteristic of lightweight bubble aggregates (LBA are presented in this paper. The LBA are produced by mixing between the foam and ordinary Portland cement according to the composition which has been set. Then, the characteristics of LBA such as density, water absorption, specific gravity, compressive strength, aggregate impact value and microscopic analysis of the LBA are analyzed. Those characteristics are identified in order to ensure that the LBA are successfully categorized into lightweight aggregate. The loose bulk density is obtained at 812.5 kg/m3 which can be categorized under lightweight aggregate group. For water absorption the value obtained is 9.7 % which is slightly higher compared to normal aggregate. Meanwhile the average specific gravity obtained for the samples of LBAis 1.75. Compressive strength for the aggregates was 17.76 MPa. The highest compressive strength for LBA foamed concrete was obtained at 25% replacement with 7.83MPa. Thus, the LBA have a significant features and characteristics that can be used as coarse aggregates in concrete.

  6. Prediction and control of the coefficient of thermal expansion of concrete

    International Nuclear Information System (INIS)

    Ziegeldorf, S.; Kleiser, K.; Hilsdorf, H.K.

    1979-01-01

    Prediction and control of the coefficient of thermal expansion of concrete. In this report various procedures for the prediction of the coefficient of thermal expansion of concrete are summarized. The values predicted with these procedures are compared to experimental data. In the experimental investigation the coefficient of thermal expansion of various types of aggregates and types of concrete both in a dry and a moist state in the temperature range RT/180 0 C have been measured. The most significant result obtained is that for equal volume fractions the thermal properties of coarse aggregates have a more pronounced effect upon thermal expansion of concrete than those of fine aggregates. In the analysis an attempt has been made to estimate the thermal expansion of concrete from the properties of the concrete components by means of a finite element procedure. On the basis of the experimental data and of the analysis of internal temperature stresses in the concrete a simple relationship for the determination of the coefficient of thermal expansion of concrete has been deduced. In this relationship different thermal properties of coarse and fine aggregates may be taken into account. Compared to other methods this relationship yields, both for dry and for moist concrete, values which are in good agreement with the experimental data. (orig.) [de

  7. Effect of aggregate type, casting, thickness and curing condition on restrained strain of mass concrete

    Directory of Open Access Journals (Sweden)

    Pongsak Choktaweekarn

    2010-08-01

    Full Text Available In this paper, a three-dimensional finite element analysis is used for computing temperature and restrained strain inmass concrete. The model takes into account time, material properties, and mix proportion dependent behavior of concrete.The hydration heat and thermal properties used in the finite element analysis are obtained from our previously proposedadiabatic temperature rise model and are used as the input in the analysis. The analysis was done by varying size of massconcrete (especially thickness and the casting method in order to explain their effect on temperature and restrained strain inmass concrete. The casting methods used in the analysis are continuous and discontinuous casting. The discontinuouscasting consists of layer casting and block casting. Different types of aggregate were used in the analysis for studying theeffect of thermal properties of aggregate on temperature and restrained strain in mass concrete. Different conditions of curing(insulation and normal curing were also studied and compared. It was found from the analytical results that the maximumtemperature increases with the increase of the thickness of structure. The use of layer casting is more effective for thermalcracking control of mass concrete. The insulation curing method is preferable for mass concrete. Aggregate with low coefficientof thermal expansion is beneficial to reduce the restrained strain.

  8. Development of lightweight concrete subfloor with ethylene vinyl acetate (EVA) aggregates waste to reduce impact sound in flooring system

    OpenAIRE

    Pacheco, Fernanda; Krumenauer, Marcelo; Reis de Medeiros, Daniel; Oliveira, Maria Fernanda; Fonseca Tutikian, Bernardo

    2017-01-01

    Abstract Comfort and habitability are requirements for housing quality, affected by underfloor system. Thus, this study aims to design lightweight concrete slabs underfloor with the use of ethylene vinyl acetate (EVA) aggregates, with two grain sizes of conventional aggregates replaced with EVA. The experimental counted on four unit mixes, varying the ratio between EVA coarse and fine aggregates and natural aggregates. The underfloor plates were molded with thickness of 3, 5 and 7 centimeters...

  9. State-of-the-Art Report on Fiber-Reinforced Lightweight Aggregate Concrete Masonry

    Directory of Open Access Journals (Sweden)

    Saul Rico

    2017-01-01

    Full Text Available Masonry construction is the most widely used building method in the world. Concrete masonry is relatively low in cost due to the vast availability of aggregates used within the production process. These aggregate materials are not always reliable for structural use. One of the principal issues associated with masonry is the brittleness of the unit. When subject to seismic loads, the brittleness of the masonry magnifies. In regions with high seismic activity and unspecified building codes or standards, masonry housing has developed into a death trap for countless individuals. A common approach concerning the issue associated with the brittle characteristic of masonry is addition of steel reinforcement. However, this can be expensive, highly dependent on skillfulness of labor, and particularly dependent on the quality of available steel. A proposed solution presented in this investigation consists of introducing steel fibers to the lightweight aggregate concrete masonry mix. Previous investigations in the field of lightweight aggregate fiber-reinforced concrete have shown an increase in flexural strength, toughness, and ductility. The outcome of this research project provides invaluable data for the production of a ductile masonry unit capable of withstanding seismic loads for prolonged periods.

  10. Cyclic Behavior of Low Rise Concrete Shear Walls Containing Recycled Coarse and Fine Aggregates.

    Science.gov (United States)

    Qiao, Qiyun; Cao, Wanlin; Qian, Zhiwei; Li, Xiangyu; Zhang, Wenwen; Liu, Wenchao

    2017-12-07

    In this study, the cyclic behaviors of low rise concrete shear walls using recycled coarse or fine aggregates were investigated. Eight low rise Recycled Aggregates Concrete (RAC) shear wall specimens were designed and tested under a cyclic loading. The following parameters were varied: replacement percentages of recycled coarse or fine aggregates, reinforcement ratio, axial force ratio and X-shaped rebars brace. The failure characteristics, hysteretic behavior, strength and deformation capacity, strain characteristics and stiffness were studied. Test results showed that the using of the Recycled Coarse Aggregates (RCA) and its replacement ratio had almost no influence on the mechanical behavior of the shear wall; however, the using of Recycled Fine Aggregates (RFA) had a certain influence on the ductility of the shear wall. When the reinforcement ratio increased, the strength and ductility also increased. By increasing the axial force ratio, the strength increased but the ductility decreased significantly. The encased brace had a significant effect on enhancing the RAC shear walls. The experimental maximum strengths were evaluated with existing design codes, it was indicated that the strength evaluation of the low rise RAC shear walls can follow the existing design codes of the conventional concrete shear walls.

  11. Stress-strain curve of concretes with recycled concrete aggregates: analysis of the NBR 8522 methodology

    Directory of Open Access Journals (Sweden)

    D. A. GUJEL

    Full Text Available ABSTRACT This work analyses the methodology "A" (item A.4 employed by the Brazilian Standard ABNT 8522 (ABNT, 2008 for determining the stress-strain behavior of cylindrical specimens of concrete, presenting considerations about possible enhancements aiming it use for concretes with recycled aggregates with automatic test equipment. The methodology specified by the Brazilian Standard presents methodological issues that brings distortions in obtaining the stress-strain curve, as the use of a very limited number of sampling points and by inducing micro cracks and fluency in the elastic behavior of the material due to the use of steady stress levels in the test. The use of a base stress of 0.5 MPa is too low for modern high load test machines designed do high strength concrete test. The work presents a discussion over these subjects, and a proposal of a modified test procedure to avoid such situations.

  12. The shakeout scenario: Meeting the needs for construction aggregates, asphalt, and concrete

    Science.gov (United States)

    Langer, W.H.

    2011-01-01

    An Mw 7.8 earthquake as described in the ShakeOut Scenario would cause significantdamage to buildings and infrastructure. Over 6 million tons of newly mined aggregate would be used for emergency repairs and for reconstruction in the five years following the event. This aggregate would be applied mostly in the form of concrete for buildings and bridges, asphalt or concrete for pavement, and unbound gravel for applications such as base course that goes under highway pavement and backfilling for foundations and pipelines. There are over 450 aggregate, concrete, and asphalt plants in the affected area, some of which would be heavily damaged. Meeting the increased demand for construction materials would require readily available permitted reserves, functioning production facilities, a supply of cement and asphalt, a source of water, gas, and electricity, and a trained workforce. Prudent advance preparations would facilitate a timely emergency response and reconstruction following such an earthquake. ?? 2011, Earthquake Engineering Research Institute.

  13. Basalt Fiber for Volcanic Slag Lightweight Aggregate Concrete Research on the Impact of Performance

    Science.gov (United States)

    Xiao, Li-guang; Li, Gen-zhuang

    2018-03-01

    In order to study the effect of basalt fiber on the mechanical properties and durability of volcanic slag lightweight aggregate concrete, the experimental study on the flexural strength, compressive strength and freeze-thaw resistance of volcanic slag concrete with different basalt fiber content were carried out, the basalt fiber was surface treated with NaOH and water glass, the results show that the surface treatment of basalt fiber can significantly improve the mechanical properties, durability and other properties of volcanic slag lightweight aggregate concrete.

  14. Properties of Normal and Recycled Brick Aggregates for Production of Medium Range (25–30 MPa Structural Strength Concrete

    Directory of Open Access Journals (Sweden)

    Suvash Chandra Paul

    2018-05-01

    Full Text Available This study compares the properties of normal and recycled brick aggregates to produce a medium range (25–30 MPa compressive strength of structural grade concrete. Up to date, brick aggregates are commonly used in structural concrete in some South Asian and African countries. Many concrete structures which were built in the last century are made from brick aggregates and some of them are already in a position of ending of their service life. At the same time, population and economic growth is forcing the demolition of many old structures. Therefore, there is a huge flow of construction and demolition waste and thereby it is necessary to recycle the waste to overcome the problem of occupying the landfill sites. For this study, recycled brick aggregates were collected from the various demolished building sites and their physical and mechanical performance were then compared with the concrete made from normal brick aggregates. It is found that the mechanical properties of recycled brick concrete are comparable to that of normal brick aggregate at medium strength level. The production cost of recycled brick concrete is also found to be 10–12% lower than normal brick aggregates.

  15. The effect of alkali-aggregate reaction on concrete bridge structures

    Directory of Open Access Journals (Sweden)

    Grković Slobodan

    2016-01-01

    Full Text Available This paper shows contemporary issues related to unfavorable effects of concrete alkali-aggregate reaction (AAR on concrete bridge structures (CBS. Although AAR unfavorable effects on CBS were identified in 1930s, it was much later that AAR was acknowledged as one of the most pronounced deterioration processes in concrete that results in damages to concrete structures. There are two basic forms of AAR: alkali-silica reaction (ASR and alkali-carbonate reaction (ACR. Compared to ACR, ASR is more prominent, especially in certain geographic parts of the world. Damages to concrete caused by the ASR have negative effect primarily on usability and durability of CBS, what is followed by the decrease in load bearing capacity of structural components and reliability of the whole structure, shortening of service life (SL and costly repairs. For CBS, simultaneous occurrence of ASR and other degradation processes in concrete, such as those caused by the presence of moisture, water, temperature variations and use of deicing salt during winter, are especially damaging. Based on review of the most relevant literature, this paper is focused on mechanisms and mechanisms factors of the ASR, related contemporary research and reliability design guidelines for CBS that are based on prevention of the initiation and development of ASR.

  16. Toxicity and environmental and economic performance of fly ash and recycled concrete aggregates use in concrete: A review.

    Science.gov (United States)

    Kurda, Rawaz; Silvestre, José D; de Brito, Jorge

    2018-04-01

    This paper presents an overview of previous studies on the environmental impact (EI) and toxicity of producing recycled concrete aggregates (RCA), fly ash (FA), cement, superplasticizer, and water as raw materials, and also on the effect of replacing cement and natural aggregates (NA) with FA and RCA, respectively, on the mentioned aspects. EI and toxicity were analysed simultaneously because considering concrete with alternative materials as sustainable depends on whether their risk assessment is high. Therefore, this study mainly focuses on the cradle-to-gate EI of one cubic meter of concrete, namely abiotic depletion potential (ADP), global warming potential (GWP), ozone depletion potential (ODP), photochemical ozone creation (POCP), acidification potential (AP), eutrophication potential (EP), non-renewable energy (PE-NRe) and renewable energy (PE-Re). In terms of toxicity, leachability (chemical and ecotoxicological characterization) was considered. The results also include the economic performance of these materials, and show that the incorporation of FA in concrete significantly decreases the EI and cost of concrete. Thus, the simultaneous incorporation of FA and RCA decrease the EI, cost, use of landfill space and natural resources extraction. Nonetheless, the leaching metals of FA decrease when they are incorporated in concrete. Relative to FA, the incorporation of RCA does not significantly affect the EI and cost of concrete, but it significantly reduces the use of landfill space and the need of virgin materials.

  17. RILEM recommendations for the prevention of damage by alkali-aggregate reactions in new concrete structures state-of-the-art report of the RILEM technical committee 219-ACS

    CERN Document Server

    Sims, Ian

    2016-01-01

    This book contains the full set of RILEM Recommendations which have been produced to enable engineers, specifiers and testing houses to design and produce concrete which will not suffer damage arising from alkali reactions in the concrete. There are five recommended test methods for aggregates (designated AAR-1 to AAR-5), and an overall recommendation which describes how these should be used to enable a comprehensive aggregate assessment (AAR-0). Additionally, there are two Recommended International Specifications for concrete (AAR-7.1 & 7.2) and a Preliminary International Specification for dams and other hydro structures (AAR-7.3), which describe how the aggregate assessment can be combined with other measures in the design of the concrete to produce a concrete with a minimised risk of developing damage from alkali-aggregate reactions.

  18. Sea Dredged Gravel versus Crushed Granite as Coarse Aggregate for Self Compacting Concrete in Aggressive Environment

    DEFF Research Database (Denmark)

    Sørensen, Eigil V.; Kristensen, Lasse Frølich

    2007-01-01

    Properties of self compacting concrete (SCC) with two types of coarse aggregate - sea dredged gravel with smooth and rounded particles and crushed granite with rough and angular particles - have been studied. Sea gravel allowed a higher aggregate proportion in the concrete leading to a higher...

  19. Intermediate-scale tests of sodium interactions with calcite and dolomite aggregate concretes

    International Nuclear Information System (INIS)

    Randich, E.; Acton, R.U.

    1983-09-01

    Two intermediate-scale tests were performed to compare the behavior of calcite and dolomite aggregate concretes when attacked by molten sodium. The tests were performed as part of an interlaboratory comparison between Sandia National Laboratories and Hanford Engineering Development Laboratories. Results of the tests at Sandia National Laboratories are reported here. The results show that both concretes exhibit similar exothermic reactions with molten sodium. The large difference in reaction vigor suggested by thermodynamic considerations of CO 2 release from calcite and dolomite was not realized. Penetration rates of 1.4 to 1.7 mm/min were observed for short periods of time with reaction zone temperatures in excess of 800 0 C during the energetic attack. The penetration was not uniform over the entire sodium-concrete contact area. Rapid attack may be localized due to inhomogeneities in the concrete. The chemical reaction zone is less then one cm thick for the calcite concrete but is about seven cm thick for the dolomite concrete

  20. Recycled Coarse Aggregate Produced by Pulsed Discharge in Water

    Science.gov (United States)

    Namihira, Takao; Shigeishi, Mitsuhiro; Nakashima, Kazuyuki; Murakami, Akira; Kuroki, Kaori; Kiyan, Tsuyoshi; Tomoda, Yuichi; Sakugawa, Takashi; Katsuki, Sunao; Akiyama, Hidenori; Ohtsu, Masayasu

    In Japan, the recycling ratio of concrete scraps has been kept over 98 % after the Law for the Recycling of Construction Materials was enforced in 2000. In the present, most of concrete scraps were recycled as the Lower Subbase Course Material. On the other hand, it is predicted to be difficult to keep this higher recycling ratio in the near future because concrete scraps increase rapidly and would reach to over 3 times of present situation in 2010. In addition, the demand of concrete scraps as the Lower Subbase Course Material has been decreased. Therefore, new way to reuse concrete scraps must be developed. Concrete scraps normally consist of 70 % of coarse aggregate, 19 % of water and 11 % of cement. To obtain the higher recycling ratio, the higher recycling ratio of coarse aggregate is desired. In this paper, a new method for recycling coarse aggregate from concrete scraps has been developed and demonstrated. The system includes a Marx generator and a point to hemisphere mesh electrode immersed in water. In the demonstration, the test piece of concrete scrap was located between the electrodes and was treated by the pulsed discharge. After discharge treatment of test piece, the recycling coarse aggregates were evaluated under JIS and TS and had enough quality for utilization as the coarse aggregate.

  1. Effect of Surrogate Aggregates on the Thermal Conductivity of Concrete at Ambient and Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Tae Sup Yun

    2014-01-01

    Full Text Available The accurate assessment of the thermal conductivity of concretes is an important part of building design in terms of thermal efficiency and thermal performance of materials at various temperatures. We present an experimental assessment of the thermal conductivity of five thermally insulated concrete specimens made using lightweight aggregates and glass bubbles in place of normal aggregates. Four different measurement methods are used to assess the reliability of the thermal data and to evaluate the effects of the various sensor types. The concrete specimens are also assessed at every 100°C during heating to ~800°C. Normal concrete is shown to have a thermal conductivity of ~2.25 W m−1 K−1. The surrogate aggregates effectively reduce the conductivity to ~1.25 W m−1 K−1 at room temperature. The aggregate size is shown not to affect thermal conduction: fine and coarse aggregates each lead to similar results. Surface contact methods of assessment tend to underestimate thermal conductivity, presumably owing to high thermal resistance between the transducers and the specimens. Thermogravimetric analysis shows that the stages of mass loss of the cement paste correspond to the evolution of thermal conductivity upon heating.

  2. Effects of oil palm shell coarse aggregate species on high strength lightweight concrete.

    Science.gov (United States)

    Yew, Ming Kun; Bin Mahmud, Hilmi; Ang, Bee Chin; Yew, Ming Chian

    2014-01-01

    The objective of this study was to investigate the effects of different species of oil palm shell (OPS) coarse aggregates on the properties of high strength lightweight concrete (HSLWC). Original and crushed OPS coarse aggregates of different species and age categories were investigated in this study. The research focused on two OPS species (dura and tenera), in which the coarse aggregates were taken from oil palm trees of the following age categories (3-5, 6-9, and 10-15 years old). The results showed that the workability and dry density of the oil palm shell concrete (OPSC) increase with an increase in age category of OPS species. The compressive strength of specimen CD3 increases significantly compared to specimen CT3 by 21.8%. The maximum achievable 28-day and 90-day compressive strength is 54 and 56 MPa, respectively, which is within the range for 10-15-year-old crushed dura OPS. The water absorption was determined to be within the range for good concrete for the different species of OPSC. In addition, the ultrasonic pulse velocity (UPV) results showed that the OPS HSLWC attain good condition at the age of 3 days.

  3. Cyclic Behavior of Low Rise Concrete Shear Walls Containing Recycled Coarse and Fine Aggregates

    Directory of Open Access Journals (Sweden)

    Qiyun Qiao

    2017-12-01

    Full Text Available In this study, the cyclic behaviors of low rise concrete shear walls using recycled coarse or fine aggregates were investigated. Eight low rise Recycled Aggregates Concrete (RAC shear wall specimens were designed and tested under a cyclic loading. The following parameters were varied: replacement percentages of recycled coarse or fine aggregates, reinforcement ratio, axial force ratio and X-shaped rebars brace. The failure characteristics, hysteretic behavior, strength and deformation capacity, strain characteristics and stiffness were studied. Test results showed that the using of the Recycled Coarse Aggregates (RCA and its replacement ratio had almost no influence on the mechanical behavior of the shear wall; however, the using of Recycled Fine Aggregates (RFA had a certain influence on the ductility of the shear wall. When the reinforcement ratio increased, the strength and ductility also increased. By increasing the axial force ratio, the strength increased but the ductility decreased significantly. The encased brace had a significant effect on enhancing the RAC shear walls. The experimental maximum strengths were evaluated with existing design codes, it was indicated that the strength evaluation of the low rise RAC shear walls can follow the existing design codes of the conventional concrete shear walls.

  4. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete.

    Science.gov (United States)

    López-Uceda, Antonio; Ayuso, Jesús; Jiménez, José Ramón; Agrela, Francisco; Barbudo, Auxiliadora; De Brito, Jorge

    2016-02-02

    This research aims to produce non-structural concrete with mixed recycled aggregates (MRA) in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%), using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results) from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors' knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

  5. Upscaling the Use of Mixed Recycled Aggregates in Non-Structural Low Cement Concrete

    Directory of Open Access Journals (Sweden)

    Antonio López-Uceda

    2016-02-01

    Full Text Available This research aims to produce non-structural concrete with mixed recycled aggregates (MRA in upscaled applications with low-cement content. Four slabs were executed with concrete made with different ratios of coarse MRA (0%, 20%, 40% and 100%, using the mix design, the mixing procedures and the facilities from a nearby concrete production plant. The analysis of the long-term compressive and splitting tensile strengths in concrete cores, extracted from the slabs, allowed the highlighting of the long-term high strength development potential of MRA incorporation. The study of cast specimens produced in situ under the same conditions as the slabs showed, firstly, that the use of MRA has a great influence on the properties related to durability, secondly, that the loss of compressive strength for total MRA incorporation relative to control concrete increases proportionally with the class strength, and, thirdly, that the mechanical properties (including Schmidt hammer results from the concrete slabs showed no significant differences relative to the control concrete for coarse aggregates replacements up to 40%. Therefore, this upscaled experimental study supports the application of concrete with 100% coarse MRA incorporation and low cement content in non-structural civil works such as bike lanes, gutters, ground slabs, leveling surfaces, and subgrades for foundations. To the best of the authors’ knowledge, there have not been any upscaled applications of concrete with MRA and low cement content.

  6. Characterization of High Density Concrete by Ultrasonic Goniometer

    International Nuclear Information System (INIS)

    Suhairy Sani; Mohamad Pauzi Ismail; Noor Azreen Masenwat; Nasharuddin Isa; Mohamad Haniza Mahmud

    2014-01-01

    This paper described the results of ultrasonic goniometer measurements on concrete containing hematite. Local hematite stones were used as aggregates to produce high density concrete for application in X-and gamma shielding. Concrete cube samples (150 mm x 150 mm x 150 mm) containing hematite as coarse aggregates were prepared by changing mix ratio, water to cement ratio (w/ c) and types of fine aggregate. All samples were cured in water for 7 days. After 28 days of casting, the concrete cubes were then cut into small size of about 10 mm x 20 mm x 30 mm so that it can be fitted into goniometer specimen holder. From this measurement, longitudinal, shear and surface Rayleigh waves in the concrete can be determined. The measurement results are explained and discussed. (author)

  7. Utilization of power plant bottom ash as aggregates in fiber-reinforced cellular concrete.

    Science.gov (United States)

    Lee, H K; Kim, H K; Hwang, E A

    2010-02-01

    Recently, millions tons of bottom ash wastes from thermoelectric power plants have been disposed of in landfills and coastal areas, regardless of its recycling possibility in construction fields. Fiber-reinforced cellular concrete (FRCC) of low density and of high strength may be attainable through the addition of bottom ash due to its relatively high strength. This paper focuses on evaluating the feasibility of utilizing bottom ash of thermoelectric power plant wastes as aggregates in FRCC. The flow characteristics of cement mortar with bottom ash aggregates and the effect of aggregate type and size on concrete density and compressive strength were investigated. In addition, the effects of adding steel and polypropylene fibers for improving the strength of concrete were also investigated. The results from this study suggest that bottom ash can be applied as a construction material which may not only improve the compressive strength of FRCC significantly but also reduce problems related to bottom ash waste.

  8. Toxicity and environmental and economic performance of fly ash and recycled concrete aggregates use in concrete: A review

    Directory of Open Access Journals (Sweden)

    Rawaz Kurda

    2018-04-01

    Full Text Available This paper presents an overview of previous studies on the environmental impact (EI and toxicity of producing recycled concrete aggregates (RCA, fly ash (FA, cement, superplasticizer, and water as raw materials, and also on the effect of replacing cement and natural aggregates (NA with FA and RCA, respectively, on the mentioned aspects. EI and toxicity were analysed simultaneously because considering concrete with alternative materials as sustainable depends on whether their risk assessment is high. Therefore, this study mainly focuses on the cradle-to-gate EI of one cubic meter of concrete, namely abiotic depletion potential (ADP, global warming potential (GWP, ozone depletion potential (ODP, photochemical ozone creation (POCP, acidification potential (AP, eutrophication potential (EP, non-renewable energy (PE-NRe and renewable energy (PE-Re. In terms of toxicity, leachability (chemical and ecotoxicological characterization was considered. The results also include the economic performance of these materials, and show that the incorporation of FA in concrete significantly decreases the EI and cost of concrete. Thus, the simultaneous incorporation of FA and RCA decrease the EI, cost, use of landfill space and natural resources extraction. Nonetheless, the leaching metals of FA decrease when they are incorporated in concrete. Relative to FA, the incorporation of RCA does not significantly affect the EI and cost of concrete, but it significantly reduces the use of landfill space and the need of virgin materials. Keywords: Materials science, Environmental science, Industry, Economics, Safety engineering

  9. Quality assurance program : bituminous concrete and central mix aggregates.

    Science.gov (United States)

    1980-01-01

    This report presents the results of a pilot quality assurance program initiated in the Richmond District in 1978. Under this program the producer's control tests are used for the acceptance of central mix aggregate and bituminous concrete and the Dep...

  10. Recycled construction debris as an aggregates. Production of concrete blocks

    OpenAIRE

    Sousa, J. G. G.; Bauer, E.; Sposto, R. M.

    2003-01-01

    This paper analyzes the use of recycled construction and demolition debris as aggregate for the construction of concrete blocks to be used in sealing masonry. Initial studies addressed the definition of parameters used in the mix of conventional materials (traditionally used in the production of concrete blocks), involving cylindrical test specimens (100x200 mm), molded with the help of a vibratory table. In addition to these definitions, and based on the mixes showing the best results, a new...

  11. Assessment of optimum threshold and particle shape parameter for the image analysis of aggregate size distribution of concrete sections

    Science.gov (United States)

    Ozen, Murat; Guler, Murat

    2014-02-01

    Aggregate gradation is one of the key design parameters affecting the workability and strength properties of concrete mixtures. Estimating aggregate gradation from hardened concrete samples can offer valuable insights into the quality of mixtures in terms of the degree of segregation and the amount of deviation from the specified gradation limits. In this study, a methodology is introduced to determine the particle size distribution of aggregates from 2D cross sectional images of concrete samples. The samples used in the study were fabricated from six mix designs by varying the aggregate gradation, aggregate source and maximum aggregate size with five replicates of each design combination. Each sample was cut into three pieces using a diamond saw and then scanned to obtain the cross sectional images using a desktop flatbed scanner. An algorithm is proposed to determine the optimum threshold for the image analysis of the cross sections. A procedure was also suggested to determine a suitable particle shape parameter to be used in the analysis of aggregate size distribution within each cross section. Results of analyses indicated that the optimum threshold hence the pixel distribution functions may be different even for the cross sections of an identical concrete sample. Besides, the maximum ferret diameter is the most suitable shape parameter to estimate the size distribution of aggregates when computed based on the diagonal sieve opening. The outcome of this study can be of practical value for the practitioners to evaluate concrete in terms of the degree of segregation and the bounds of mixture's gradation achieved during manufacturing.

  12. Chapter K: Progress in the Evaluation of Alkali-Aggregate Reaction in Concrete Construction in the Pacific Northwest, United States and Canada

    Science.gov (United States)

    Shrimer, Fred H.

    2005-01-01

    users of the concrete aggregates mined from these deposits. This situation is complicated by the length of time typically required for AAR to become noticeable in concrete construction in the Pacific Northwest, commonly on such a scale that other deterioration mechanisms may have masked the effects of AAR. Distinguishing between the effects of AAR and those related to other problems in concrete is important for understanding the nature and severity of AAR throughout the Pacific Northwest. Furthermore, developing an understanding of the extent of the problem will assist efforts to maximize the intelligent and stewardly use of aggregate resources in the Pacific Northwest. This chapter illustrates the current 'state of the art' of AAR studies in the Pacific Northwest, a region with a common geologic heritage as well as many distinct geologic elements. The optimal use of aggregates in the construction of concrete structures that will achieve their design life is possible through an understanding of the engineering and geologic properties of these aggregates and of their geologic setting.

  13. Preliminary studies on steel slag as a substitute for coarse aggregate on concrete

    Directory of Open Access Journals (Sweden)

    Karolina Rahmi

    2017-01-01

    Full Text Available The development of science and technology in the field of construction that is rapidly increasing, is always followed by the growing community needs for infrastructure facilities, such as buildings, bridges and other construction. One of the key element in that development is concrete. Due to the rapid development of science and technology in the field of construction, it’s required a building material which has better advantage than the materials of the existing building. To obtain a better building materials, one alternative is the use of waste as aggregate in concrete mixture. In this study the authors using waste steel waste (steel slag as a substitute for coarse aggregate. Steel slag used is steel waste from PT. Growth Sumatra Industry. The gravel substitution variations is 0%, 15%, and 25% and the testing was done by the slump test, compressive strength and flexural strength of concrete. From the test results obtained optimum compressive strength variation occurs in 25% substitution of steel slag gravel amounted to 40.481 MPa, whereas for the optimum bending capacity contained in variations of 25% substitution of steel slag gravel amounted to 19.592 N / mm2. And for optimum slump value obtained on the variation of normal concrete. This shows the workability of the concrete normally higher than the other variation.

  14. Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard.

    Science.gov (United States)

    Rodríguez-Robles, Desirée; García-González, Julia; Juan-Valdés, Andrés; Morán-Del Pozo, Julia Mª; Guerra-Romero, Manuel I

    2014-08-13

    Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW.

  15. Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard

    Directory of Open Access Journals (Sweden)

    Desirée Rodríguez-Robles

    2014-08-01

    Full Text Available Construction and demolition waste (CDW constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA and ceramic recycled aggregates (CerRA. In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08 to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW.

  16. A Review on the Use of Agriculture Waste Material as Lightweight Aggregate for Reinforced Concrete Structural Members

    Directory of Open Access Journals (Sweden)

    Kim Hung Mo

    2014-01-01

    Full Text Available The agriculture industry is one of the main industries in the Southeast Asia region due to its favourable conditions for plantations. In fact, Southeast Asia region is the world’s largest producer of palm oil and coconut. Nevertheless, vast plantation of these agriculture products leads to equally large amount of waste materials emanating from these industries. Previously, researchers have attempted to utilize the resulting waste materials such as oil palm shell, palm oil clinker, and coconut shell from these industries as lightweight aggregate to produce structural grade lightweight aggregate concrete. In order to promote the concept of using such concrete for actual structural applications, this paper reviews the use of such agriculture-based lightweight aggregate concrete in reinforced concrete structural members such as beam and slab, which were carried out by researchers in the past. The behaviour of the structural members under flexural, shear, and torsional load was also summarized. It is hoped that the knowledge attained from the paper will provide design engineers with better idea and proper application of design criteria for structural members using such agriculture waste as lightweight aggregate.

  17. Strengths and Failure Characteristics of Self-Compacting Concrete Containing Recycled Waste Glass Aggregate

    Directory of Open Access Journals (Sweden)

    Rahman Khaleel AL-Bawi

    2017-01-01

    Full Text Available The effects of different proportions of green-colored waste glass (WG cullet on the mechanical and fracture properties of self-compacting concrete (SCC were experimentally investigated. Waste bottles were collected, washed, crushed, and sieved to prepare the cullet used in this study. Cullet was incorporated at different percentages (0%, 20%, 40%, 60%, 80%, and 100% by weight instead of natural fine aggregate (NFA and/or natural coarse aggregate (NCA. Three SCC series were designed with a constant slump flow of 700±30 mm, total binder content of 570 kg/m3 and at water-to-binder (w/b ratio of 0.35. Moreover, fly ash (FA was used in concrete mixtures at 20% of total binder content. Mechanical aspects such as compressive, splitting tensile, and net flexural strengths and modulus of elasticity of SCC were investigated and experimentally computed at 28 days of age. Moreover, failure characteristics of the concretes were also monitored via three-point bending test on the notched beams. The findings revealed that the mechanical properties as well as fracture parameters were adversely influenced by incorporating of WG cullet. However, highest reduction of compressive strength did not exceed 43% recorded at 100% WG replacement level. Concretes containing WG showed less brittle behavior than reference concrete at any content.

  18. Engineering properties of sintered waste sludge as lightweight aggregate in a densified concrete mixture

    Institute of Scientific and Technical Information of China (English)

    彭予柱

    2009-01-01

    The global trend towards carbon reduction,energy conservation,and sustainable use of resources has led to an increased focus on the use of waste sludge in construction.We used waste sludge from a reservoir to produce high-strength sintered lightweight aggregate,and then used the densified mixture design algorithm to create high-performance concrete from the sintered aggregate with only small amounts of mixing water and cement.Ultrasonic,electrical resistance and concrete strength efficiency tests were perfo...

  19. Microstructure of Concrete with Aggregates from Construction and Demolition Waste Recycling Plants.

    Science.gov (United States)

    Bravo, Miguel; Santos Silva, António; de Brito, Jorge; Evangelista, Luís

    2016-02-01

    This paper intends to analyze the microstructure of concrete with recycled aggregates (RA) from construction and demolition waste from various Portuguese recycling plants. To that effect, several scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed. Various concrete mixes were evaluated in order to analyze the influence of the RA's collection point and consequently of their composition on the mixes' characteristics. Afterward all the mixes were subjected to the capillary water absorption test in order to quantitatively evaluate their porosity. Results from the SEM/EDS analysis were compared with those from capillary water absorption test. The SEM/EDS analysis showed that the bond capacity of aggregates to the new cement paste is greatly influenced by the RA's nature. On the other hand, there was an increase in porosity with the incorporation of RA.

  20. Influence of Porous Aggregate on the Properties of Foamed Concrete

    Directory of Open Access Journals (Sweden)

    Namsone Elvija

    2016-12-01

    Full Text Available Nowadays energy-efficient use of building resources is getting more and more popular. Technological developments have promoted production of new building materials with improved physical, mechanical and thermal properties. Foamed concrete with porous aggregate can serve as an alternative material for the existing lightweight concrete materials. This building material shows good mechanical and thermal properties, as well as capillary absorption and shrinkage test results that attest the longevity of this building material.

  1. Effects of Oil Palm Shell Coarse Aggregate Species on High Strength Lightweight Concrete

    Directory of Open Access Journals (Sweden)

    Ming Kun Yew

    2014-01-01

    Full Text Available The objective of this study was to investigate the effects of different species of oil palm shell (OPS coarse aggregates on the properties of high strength lightweight concrete (HSLWC. Original and crushed OPS coarse aggregates of different species and age categories were investigated in this study. The research focused on two OPS species (dura and tenera, in which the coarse aggregates were taken from oil palm trees of the following age categories (3–5, 6–9, and 10–15 years old. The results showed that the workability and dry density of the oil palm shell concrete (OPSC increase with an increase in age category of OPS species. The compressive strength of specimen CD3 increases significantly compared to specimen CT3 by 21.8%. The maximum achievable 28-day and 90-day compressive strength is 54 and 56 MPa, respectively, which is within the range for 10–15-year-old crushed dura OPS. The water absorption was determined to be within the range for good concrete for the different species of OPSC. In addition, the ultrasonic pulse velocity (UPV results showed that the OPS HSLWC attain good condition at the age of 3 days.

  2. Comparative performance of various smart aggregates during strength gain and damage states of concrete

    International Nuclear Information System (INIS)

    Saravanan, T Jothi; Balamonica, K; Priya, C Bharathi; Gopalakrishnan, N; Reddy, A Likhith

    2015-01-01

    Information regarding the early strength gain of fresh concrete determines the time for the removal of form work and the transfer of pre-stressing forces for pre-stressed concrete. An ultrasonic based non-destructive evaluation of early strength gain may not work for concrete in fluid and semi-solid phases. A possible alternative is a lead zirconate titanate (PZT)-based smart aggregate embedded in concrete, which can evaluate the micro-structural and rheological properties right from the fluid phase. A set of five smart aggregates embedded in a concrete cube were investigated for their suitability to evaluate electromechanical impedance (EMI) signatures. Cubes were loaded to failure and the EMI during progressive strength loss under compressive loads was studied. To show the generalized applicability of this, experimental results for the performance of typical smart aggregates on a larger specimen, namely a concrete beam, are also discussed. Different statistical metrics were examined computationally on a three peak admittance curve with a parametric variation of stiffness, damping and simple scaling. The root mean square deviation (RMSD), mean absolute percentage deviation (MAPD), cross correlation (CC) and modified cross correlation (MCC) were investigated, in addition to the rate of change of the RMSD. Variations between the reference and modified states were studied. Both stiffness and mass gains occur for the smart aggregates, resulting in an increase or decrease of frequency and amplitude peaks due to progressive C-S-H gel formation. The trend of increasing stiffness and the consequent rightward shift of the resonant peaks and decrease of damping, with the consequent upward shift of amplitudes that happens during curing and strength gain, was observed to be reversed during the application of damaging loads. (paper)

  3. An investigation on the use of shredded waste PET bottles as aggregate in lightweight concrete

    International Nuclear Information System (INIS)

    Akcaoezoglu, Semiha; Atis, Cengiz Duran; Akcaoezoglu, Kubilay

    2010-01-01

    In this work, the utilization of shredded waste Poly-ethylene Terephthalate (PET) bottle granules as a lightweight aggregate in mortar was investigated. Investigation was carried out on two groups of mortar samples, one made with only PET aggregates and, second made with PET and sand aggregates together. Additionally, blast-furnace slag was also used as the replacement of cement on mass basis at the replacement ratio of 50% to reduce the amount of cement used and provide savings. The water-binder (w/b) ratio and PET-binder (PET/b) ratio used in the mixtures were 0.45 and 0.50, respectively. The size of shredded PET granules used in the preparation of mortar mixtures were between 0 and 4 mm. The results of the laboratory study and testing carried out showed that mortar containing only PET aggregate, mortar containing PET and sand aggregate, and mortars modified with slag as cement replacement can be drop into structural lightweight concrete category in terms of unit weight and strength properties. Therefore, it was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete. The use of shredded waste PET granules due to its low unit weight reduces the unit weight of concrete which results in a reduction in the death weight of a structural concrete member of a building. Reduction in the death weight of a building will help to reduce the seismic risk of the building since the earthquake forces linearly dependant on the dead-weight. Furthermore, it was also concluded that the use of industrial wastes such as PET granules and blast-furnace slag in concrete provides some advantages, i.e., reduction in the use of natural resources, disposal of wastes, prevention of environmental pollution, and energy saving.

  4. An investigation on the use of shredded waste PET bottles as aggregate in lightweight concrete.

    Science.gov (United States)

    Akçaözoğlu, Semiha; Atiş, Cengiz Duran; Akçaözoğlu, Kubilay

    2010-02-01

    In this work, the utilization of shredded waste Poly-ethylene Terephthalate (PET) bottle granules as a lightweight aggregate in mortar was investigated. Investigation was carried out on two groups of mortar samples, one made with only PET aggregates and, second made with PET and sand aggregates together. Additionally, blast-furnace slag was also used as the replacement of cement on mass basis at the replacement ratio of 50% to reduce the amount of cement used and provide savings. The water-binder (w/b) ratio and PET-binder (PET/b) ratio used in the mixtures were 0.45 and 0.50, respectively. The size of shredded PET granules used in the preparation of mortar mixtures were between 0 and 4 mm. The results of the laboratory study and testing carried out showed that mortar containing only PET aggregate, mortar containing PET and sand aggregate, and mortars modified with slag as cement replacement can be drop into structural lightweight concrete category in terms of unit weight and strength properties. Therefore, it was concluded that there is a potential for the use of shredded waste PET granules as aggregate in the production of structural lightweight concrete. The use of shredded waste PET granules due to its low unit weight reduces the unit weight of concrete which results in a reduction in the death weight of a structural concrete member of a building. Reduction in the death weight of a building will help to reduce the seismic risk of the building since the earthquake forces linearly dependent on the dead-weight. Furthermore, it was also concluded that the use of industrial wastes such as PET granules and blast-furnace slag in concrete provides some advantages, i.e., reduction in the use of natural resources, disposal of wastes, prevention of environmental pollution, and energy saving.

  5. Comminution and sizing processes of concrete block waste as recycled aggregates.

    Science.gov (United States)

    Gomes, P C C; Ulsen, C; Pereira, F A; Quattrone, M; Angulo, S C

    2015-11-01

    Due to the environmental impact of construction and demolition waste (CDW), recycling is mandatory. It is also important that recycled concrete aggregates (RCA) are used in concrete to meet market demands. In the literature, the influence of RCAs on concrete has been investigated, but very limited studies have been conducted on how the origin of concrete waste and comminution processes influence RCA characteristics. This paper aims to investigate the influence of three different comminution and sizing processes (simple screening, crushing and grinding) on the composition, shape and porosity characteristics of RCA obtained from concrete block waste. Crushing and grinding implies a reduction of RCA porosity. However, due to the presence of coarse quartz rounded river pebbles in the original concrete block mixtures, the shape characteristics deteriorated. A large amount of powder (<0.15 mm) without detectable anhydrous cement was also generated. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. The effect of steel slag as a coarse aggregate and Sinabung volcanic ash a filler on high strength concrete

    Science.gov (United States)

    Karolina, R.; Putra, A. L. A.

    2018-02-01

    The Development of concrete technology is continues to grow. The requisite for efficient constructions that are often viewed in terms of concrete mechanical behavior, application on the field, and cost estimation of implementation increasingly require engineers to optimize construction materials, especially for concrete materials. Various types of concrete have now been developed according to their needs, such as high strength concrete. On high strength concrete design, it is necessary to consider several factors that will affect the reach of the quality strength, Those are cement, water cement ratio (w/c), aggregates, and proper admixture. In the use of natural mineral, it is important for an engineer to keep an eye on the natural conditions that have been explored. So the selection of aggregates as possible is a material that is not causing nature destruction. On this experiment the use of steel slag from PT.Growth Sumatra Industry as a substitute of coarse and fine aggregate, and volcanic ash of mount Sinabung as microsilka in concrete mixture substituted to create high strength concrete that is harmless for the environment. The use of mount sinabung volcanic ash as microsilika coupled with the use of Master Glenium Sky 8614 superplasticizer. This experiment intend to compare high strength concrete based slag steel as the main constituent aggregates and high strength concrete with a conventional mixture. The research result for 28 days old concrete shows that conventional concrete compressive strength is 67.567 MPa, slag concrete 75.958 Mpa, conventional tensile strength 5.435 Mpa while slag concrete 5.053 Mpa, conventional concrete bending strength 44064.96 kgcm while concrete slag 51473.94 kgcm and modulus of conventional concrete fracture 124.978 kg / cm2 while slag concrete 145.956 kg / cm2. Both concrete slump values shows similar results due to the use of superplasticizer.

  7. Cement treated recycled crushed concrete and masonry aggregates for pavements

    NARCIS (Netherlands)

    Xuan, D.X.

    2012-01-01

    This research is focusing on the characterization of the mechanical and deformation properties of cement treated mixtures made of recycled concrete and masonry aggregates (CTMiGr) in relation to their mixture variables. An extensive laboratory investigation was carried out, in which the mechanical

  8. Effect of mixing methods and aggregate type on strength of hardened concrete

    International Nuclear Information System (INIS)

    Elhadi, S.

    2006-01-01

    The objective of the research contained in this paper is to study the effect on strength of concrete which can be caused by changing method of concrete mix with or without changing aggregate crushing value under hand or mechanical compaction, and to compare results obtained when nondestructive testing techniques are used. It has been found that all methods of mix design are nearly identical in predicting the strength under a known value of w/c ratio. Up to strength of about 30 N/mm 2 , hand and mechanical compaction seems to be identical in all methods of concrete mixing. Important results regarding destructive and non-destructive testing has been drawn from the study.(Author)

  9. Quality Assessment of Mixed and Ceramic Recycled Aggregates from Construction and Demolition Wastes in the Concrete Manufacture According to the Spanish Standard †

    Science.gov (United States)

    Rodríguez-Robles, Desirée; García-González, Julia; Juan-Valdés, Andrés; Pozo, Julia Mª Morán-del; Guerra-Romero, Manuel I

    2014-01-01

    Construction and demolition waste (CDW) constitutes an increasingly significant problem in society due to the volume generated, rendering sustainable management and disposal problematic. The aim of this study is to identify a possible reuse option in the concrete manufacturing for recycled aggregates with a significant ceramic content: mixed recycled aggregates (MixRA) and ceramic recycled aggregates (CerRA). In order to do so, several tests are conducted in accordance with the Spanish Code on Structural Concrete (EHE-08) to determine the composition in weight and physic-mechanical characteristics (particle size distributions, fine content, sand equivalent, density, water absorption, flakiness index, and resistance to fragmentation) of the samples for the partial inclusion of the recycled aggregates in concrete mixes. The results of these tests clearly support the hypothesis that this type of material may be suitable for such partial replacements if simple pretreatment is carried out. Furthermore, this measure of reuse is in line with European, national, and regional policies on sustainable development, and presents a solution to the environmental problem caused by the generation of CDW. PMID:28788164

  10. Study on identically voided pervious concrete made with different sized aggregates

    Science.gov (United States)

    Kastro Kiran, V.; Anand, K. B.

    2018-02-01

    Pervious concrete (PC) is also known as no fines concrete and has been found to be a reliable stormwater management tool. As a substitution for conventional impervious pavement, PC usage has been increasing during recent years. PC made with different sized aggregate shows different void ratios and changed properties. As void ratio plays a notable role on strength and permeability of PC, this study aims to focus on properties of PC at identical void ratio of 20%, made using aggregates of three size ranges, viz., 4.75-6mm, 10-12.5mm, and 10-20mm. Appropriate alternatives were used to maintain the identical void ratio. As the permeation capacity of PC gets reduced due to the clogging tendency, the life of PC will also get reduced. Hence, to make the PC to sustain for a long time it is necessary to study the clogging behavior. This study investigates the tendency of PC for clogging and the potential for regaining the permeability through de-clogging methods. Clogging tendency of PC is studied by using two sizes (coarse and fine) of clog particles and the changes in permeability are observed. Efficiency of declogging methods like pressure washing and vacuum suction on PC with different sized aggregates are also evaluated.

  11. Comparative Study on Carbonated and Non-Carbonated Recycled Aggregate Concrete with Glass Powder as Partial Replacement for OPC

    Directory of Open Access Journals (Sweden)

    Abhishek Patil

    2017-12-01

    Full Text Available Recycled aggregates (RA possess the ability to be recycled, if undesirable properties are counteracted viz, porous mortar attached to it, with high water absorption and low density, this technique, accelerated carbonation can be one such to technique to counteract undesirable properties of RA, replacement of 20% of cement by glass powder assists in reducing w/c ratio[1][6] when used in concrete[2] suppress ASR reaction[1], this paper explains a new possibility of recycling concrete, work done and findings for improvising Recycled aggregate concrete (RAC and exploring the feasibility for use of RA in the near future.

  12. Photocatalytic activity of titanium dioxide modified concrete materials - influence of utilizing recycled glass cullets as aggregates.

    Science.gov (United States)

    Chen, Jun; Poon, Chi-Sun

    2009-08-01

    Combining the use of photocatalysts with cementitious materials is an important development in the field of photocatalytic air pollution mitigation. This paper presents the results of a systematic study on assessing the effectiveness of pollutant degradation by concrete surface layers that incorporate a photocatalytic material - Titanium Dioxide. The photocatalytic activity of the concrete samples was determined by photocatalytic oxidation of nitric oxide (NO) in the laboratory. Recycled glass cullets, derived from crushed waste beverage bottles, were used to replace sand in preparing the concrete surface layers. Factors, which may affect the pollutant removal performance of the concrete layers including glass color, aggregate size and curing age, were investigated. The results show a significant enhancement of the photocatalytic activity due to the use of glass cullets as aggregates in the concrete layers. The samples fabricated with clear glass cullets exhibited threefold NO removal efficiency compared to the samples fabricated with river sand. The light transmittance property of glass was postulated to account for the efficiency improvement, which was confirmed by a separate simulation study. But the influence of the size of glass cullets was not evident. In addition, the photocatalytic activity of concrete surface layers decreased with curing age, showing a loss of 20% photocatalytic activity after 56-day curing.

  13. Physicochemical characterization of steel slag post-processed as aggregate for sustainable concrete

    International Nuclear Information System (INIS)

    Souza, B.P. de; Fontes, W.C.; Carvalho, J.M.F. de; Mol, R.M.R.; Costa, E.C.P. da; Peixoto, R.A.F.

    2016-01-01

    The concrete is the material most widely used in construction, consuming a large amount of natural resources for its production. Therefore, this work analyzes the technical and environmental aspects of concrete with full replacement of natural aggregates for processed LD steelmaking slag. The experimental program comprehends physical characterization - particle size distribution, moisture content, bulk and specific density - and elemental chemical characterization with X-Ray Fluorescence, and mineralogical characterization via X-Ray Diffraction. Morphological characterization was performed through a stereomicroscope. From these results, concrete with compressive strengths of 20 and 40 Mpa were developed, with ABPC methodology. These were characterized in the fresh and hardened states, obtaining results favorable to the steelmaking slag application in Portland cement concrete. This sustainable concrete features properties similar conventional concrete, and contributing to sustainability of buildings. (author)

  14. Fundamental research on isotherm capillary absorption of concrete by neutron radiography

    International Nuclear Information System (INIS)

    Kanematsu, Manabu; Tsuchiya, Naoko; Noguchi, Takafumi

    2013-01-01

    This study focuses on the absorption process of concrete to determine the influence of aggregates on the local water behavior in concrete, by using neutron radiography. At first, water quantification method by using thermal neutron radiography is summarized which is developed in previous researches. With this method, the water absorption process was examined in concrete specimens containing artificial cylindrical aggregates. Using the obtained hydraulic diffusivity, an unsteady water diffusion analysis captured the experimentally observed water distribution around the aggregates. The result shows that the water behavior can be well explained by the geometric layout of the aggregates. (author)

  15. A comparative study of recycled aggregates from concrete and mixed debris as material for unbound road sub-base

    International Nuclear Information System (INIS)

    Jimenez, J. R.; Agrela, F.; Ayuso, J.; Lopez, M.

    2011-01-01

    Seven different types of recycled aggregates from construction and demolition waste (CDW) have been evaluated as granular materials for unbound road sub bases construction. The results showed that recycled concrete aggregates complied with all specifications for using in the construction of unbound structural layers (sub-base) for T3 and T4 traffic categories according to the Spanish General Technical Specification for Road Construction (PG-3). Some mixed recycled aggregates fell short of some specifications due to a high content of sulphur compounds and poor fragmentation resistance. Sieving off the fine fraction prior to crushing the mixed CDW reduce the total sulphur content and improve the quality of the mixed recycled aggregates, by contrast, pre-sieving concrete CDW had no effect on the quality of the resulting aggregates. The results were compared with a crushed limestone as natural aggregate. (Author) 23 refs.

  16. Study of Compressive Strength of Concrete with Coal Power Plant Fly Ash as Partial Replacement of Cement and Fine Aggregate

    Directory of Open Access Journals (Sweden)

    FAREED AHMED MEMON

    2010-10-01

    Full Text Available This research study comprises of concrete cubes made with Ordinary Portland Cement and with different configurations of fly ash by replacing cement and fine aggregate. To achieve the aim of this study, total 81 concrete cubes were cast. Among 81 cubes, 9 cubes were made with normal concrete, 36 cubes were made by replacing 25%, 50%, 75% and 100% of fine aggregate with fly ash and 36 cubes were made by replacing 10%, 25%, 50%, and 75% of cement with fly ash. The cubes were 6\\" x 6\\" in cross-section, and the mix design was aimed for 5000 psi. After proper curing of all 81 cubes, they were tested at 3, 7 and 28 days curing age. The cubes were tested in Forney Universal Testing Machine. By analyzing the test results of all the concrete cubes, the following main findings have been drawn. The compressive strength of concrete cubes made by replacing 100 % fine aggregate by fly ash was higher than the concrete cubes made with Ordinary Portland Cement at all 3, 7 and 28 days curing ages. On the other hand, the compressive strength of concrete cubes made by replacing 10 % and 25 % cement by fly ash was slightly lower than the concrete cubes made with Ordinary Portland Cement at all curing ages, whereas, the compressive strength of concrete cubes made by replacing 50 % and 75 % of cement by fly ash were quite lower than the concrete cubes made with Ordinary Portland Cement at all curing ages.

  17. Mechanical Behavior of Recycled Aggregate Concrete-Filled Steel Tubular Columns before and after Fire

    Directory of Open Access Journals (Sweden)

    Wenchao Liu

    2017-03-01

    Full Text Available Recycled aggregate concrete (RAC is an environmentally friendly building material. This paper investigates the mechanical behavior of recycled aggregate concrete filled steel tube (RACFST columns exposed to fire. Two groups of 12 columns were designed and tested, under axial compression, before and after fire, to evaluate the degradation of bearing capacity due to fire exposure. Six specimens were subjected to axial compression tests at room temperature and the other six specimens were subjected to axial compression tests after a fire exposure. The main parameters of the specimens include the wall thickness of the steel tube (steel content and the type of concrete materials. Several parameters as obtained from the experimental results were compared and analyzed, including the load-bearing capacity, deformation capacity, and failure characteristics of the specimens. Meanwhile, rate of loss of bearing capacity of specimens exposed to fire were calculated based on the standards EC4 and CECS28:90. The results show that concrete material has a large influence on the rate of loss of bearing capacity in the case of a relatively lower steel ratio. While steel content has little effect on the rate of loss of bearing capacity of concrete-filled steel tube (CFST columns after fire, it has a relatively large influence on the loss rate of bearing capacity of the RACFST columns. The loss of bearing capacity of the specimens from the experiment is more serious than that from the calculation. As the calculated values are less conservative, particular attention should be given to the application of recycled aggregate concrete in actual structures.

  18. Mechanical Behavior of Recycled Aggregate Concrete-Filled Steel Tubular Columns before and after Fire.

    Science.gov (United States)

    Liu, Wenchao; Cao, Wanlin; Zhang, Jianwei; Wang, Ruwei; Ren, Lele

    2017-03-09

    Recycled aggregate concrete (RAC) is an environmentally friendly building material. This paper investigates the mechanical behavior of recycled aggregate concrete filled steel tube (RACFST) columns exposed to fire. Two groups of 12 columns were designed and tested, under axial compression, before and after fire, to evaluate the degradation of bearing capacity due to fire exposure. Six specimens were subjected to axial compression tests at room temperature and the other six specimens were subjected to axial compression tests after a fire exposure. The main parameters of the specimens include the wall thickness of the steel tube (steel content) and the type of concrete materials. Several parameters as obtained from the experimental results were compared and analyzed, including the load-bearing capacity, deformation capacity, and failure characteristics of the specimens. Meanwhile, rate of loss of bearing capacity of specimens exposed to fire were calculated based on the standards EC4 and CECS28:90. The results show that concrete material has a large influence on the rate of loss of bearing capacity in the case of a relatively lower steel ratio. While steel content has little effect on the rate of loss of bearing capacity of concrete-filled steel tube (CFST) columns after fire, it has a relatively large influence on the loss rate of bearing capacity of the RACFST columns. The loss of bearing capacity of the specimens from the experiment is more serious than that from the calculation. As the calculated values are less conservative, particular attention should be given to the application of recycled aggregate concrete in actual structures.

  19. Development of a stress-mode sensitive viscoelastic constitutive relationship for asphalt concrete: experimental and numerical modeling

    Science.gov (United States)

    Karimi, Mohammad M.; Tabatabaee, Nader; Jahanbakhsh, H.; Jahangiri, Behnam

    2017-08-01

    Asphalt binder is responsible for the thermo-viscoelastic mechanical behavior of asphalt concrete. Upon application of pure compressive stress to an asphalt concrete specimen, the stress is transferred by mechanisms such as aggregate interlock and the adhesion/cohesion properties of asphalt mastic. In the pure tensile stress mode, aggregate interlock plays a limited role in stress transfer, and the mastic phase plays the dominant role through its adhesive/cohesive and viscoelastic properties. Under actual combined loading patterns, any coordinate direction may experience different stress modes; therefore, the mechanical behavior is not the same in the different directions and the asphalt specimen behaves as an anisotropic material. The present study developed an anisotropic nonlinear viscoelastic constitutive relationship that is sensitive to the tension/compression stress mode by extending Schapery's nonlinear viscoelastic model. The proposed constitutive relationship was implemented in Abaqus using a user material (UMAT) subroutine in an implicit scheme. Uniaxial compression and indirect tension (IDT) testing were used to characterize the viscoelastic properties of the bituminous materials and to calibrate and validate the proposed constitutive relationship. Compressive and tensile creep compliances were calculated using uniaxial compression, as well as IDT test results, for different creep-recovery loading patterns at intermediate temperature. The results showed that both tensile creep compliance and its rate were greater than those of compression. The calculated deflections based on these IDT test simulations were compared with experimental measurements and were deemed acceptable. This suggests that the proposed viscoelastic constitutive relationship correctly demonstrates the viscoelastic response and is more accurate for analysis of asphalt concrete in the laboratory or in situ.

  20. Production of Controlled Low Strength Material Utilizing Waste Paper Sludge Ash and Recycled Aggregate Concrete

    Directory of Open Access Journals (Sweden)

    Azmi A. N.

    2016-01-01

    Full Text Available Recently, the best method to make the concrete industry more sustainable was using the waste materials to replace the natural resources. Currently waste paper sludge is a major economic and environmental problem in this country. In this research, the alternative method is to dwindle the usage of natural resources and the usage of cement in the construction. This method is to replace the usage of cement with the waste paper sludge ash (WPSA and to use the recycle aggregate collected from the construction is used. The WPSA has ingredient likely cement such as self-cementation but for a low strength. The research was conducted at heavy laboratory UITM Pulau Pinang. Meanwhile, the WPSA is collected at MNI Industries at Mentakab, Pahang. The recycle aggregate is a separated half, which were fine aggregate and the coarse aggregate with the specific size. In this research, the ratio is divided into two (2 which is 1:1 and 1:2 for the aggregate and difference percentage levels of WPSA. The percentage levels of WPSA that use in this research are 10%, 20%, 30%, 40%, 50%, and 60%. A total of 36 cubes were prepared. Aim of this research is to develop a simple design approach for the mixture proportioning of WPSA and recycle concrete aggregate (RCA within the concrete and to assess the effect of concrete mix with different percentage of WPSA and RCA ratio on the properties. It is found that the best design mix that achieves control low strength material (CLSM is on 30% of WPSA with the ratio 1:2 on day 28 of compression test.

  1. The influence of the coarse aggregates from different mineralogy on the mechanical properties of the high-performance concrete

    International Nuclear Information System (INIS)

    Magalhaes, A.G.; Calixto, J.M.; Franca, E.P.; Aguilar, M.T.P.; Vasconcelos, W.L.

    2006-01-01

    Concrete in normal conditions is a versatile and strong construction material. However under certain environmental conditions it may deteriorate in a short period of time. This fact has led researchers in recent times to develop the high-performance concrete. In this scenario, the aim of this paper is to present the effects of the different types of coarse aggregate on the mechanical properties of high performance concrete. Limestone, granite, gneiss and basalt were used as coarse aggregates. Their characterization consisted of chemical analysis, x-ray diffraction and optical microscopy. The compressive strength and the modulus of elasticity were the investigated mechanical properties. The test results indicate expressively the better performance of the concretes fabricated with basalt, granite and gneiss aggregates. (author)

  2. Recycling ground granulated blast furnace slag as cold bonded artificial aggregate partially used in self-compacting concrete.

    Science.gov (United States)

    Gesoğlu, Mehmet; Güneyisi, Erhan; Mahmood, Swara Fuad; Öz, Hatice Öznur; Mermerdaş, Kasım

    2012-10-15

    Ground granulated blast furnace slag (GGBFS), a by-product from iron industry, was recycled as artificial coarse aggregate through cold bonding pelletization process. The artificial slag aggregates (ASA) replaced partially the natural coarse aggregates in production of self-compacting concrete (SCC). Moreover, as being one of the most widely used mineral admixtures in concrete industry, fly ash (FA) was incorporated as a part of total binder content to impart desired fluidity to SCCs. A total of six concrete mixtures having various ASA replacement levels (0%, 20%, 40%, 60%, and 100%) were designed with a water-to-binder (w/b) ratio of 0.32. Fresh properties of self-compacting concretes (SCC) were observed through slump flow time, flow diameter, V-funnel flow time, and L-box filling height ratio. Compressive strength of hardened SCCs was also determined at 28 days of curing. It was observed that increasing the replacement level of ASA resulted in decrease in the amount of superplasticizer to achieve a constant slump flow diameter. Moreover, passing ability and viscosity of SCC's enhanced with increasing the amount of ASA in the concrete. The maximum compressive strength was achieved for the SCC having 60% ASA replacement. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Mechanical Properties of High Strength Concrete Containing Coal Bottom Ash and Oil-Palm Boiler Clinker as Fine Aggregates

    Directory of Open Access Journals (Sweden)

    Soofinajafi Mahmood

    2016-01-01

    Full Text Available This research aims to utilize Coal Furnace Bottom ash (CBA and Oil-Palm Boiler Clinker (OPBC as fine aggregate in concrete mix proportions. They are solid wastes from power plant and Oil Palm industry, respectively. Since these by-products do not have any primary use and are pure waste, an opportunity to use them as aggregate in concrete industry not only is economical but also will be an environmental friendly opportunity leading towards a more sustainable production chain. CBA and OPBC sands had similar grading to normal sand but have lower density and higher water absorption. In a high strength concrete, normal sand was replaced up to 25% with either CBA or OPBC. Test results showed that although water absorption of these wastes was more than normal sand but the slump value of concrete containing each of these wastes showed that these concretes had good workability. All mixes containing these wastes had slightly lower compressive strength at early ages and equivalent or higher compressive strength at later ages compared to control mix. The 28-day compressive strength of these concretes was in the range of 69–76 MPa which can be categorized as high strength concrete. In general, the performance of OPBC was better than CBA at 25% replacement level. However, it is recommended that at least 12.5% of total volume of fine aggregate in a high strength concrete is used of CBA or OPBC.

  4. Performance estimation for concretes made with recycled aggregates of construction and demolition waste of some Brazilian cities

    Directory of Open Access Journals (Sweden)

    Antonio Eduardo Bezerra Cabral

    2012-12-01

    Full Text Available The aim of this paper is to verify the influence of composition variability of recycled aggregates (RA of construction and demolition wastes (CDW on the performance of concretes. Performance was evaluated building mathematical models for compressive strength, modulus of elasticity and drying shrinkage. To obtain such models, an experimental program comprising 50 concrete mixtures was carried out. Specimens were casted, tested and results for compressive strength, modulus of elasticity and drying shrinkage were statistically analyzed. Models inputs are CDW composition observed at seven Brazilian cities. Results confirm that using RA from CDW for concrete building is quite feasible, independently of its composition, once compressive strength and modulus of elasticity still reached considerable values. We concluded the variability presented by recycled aggregates of CDW does not compromise their use for concrete building. However, this information must be used with caution, and experimental tests should always be performed to certify concrete properties.

  5. Using a centrifuge for quality control of pre-wetted lightweight aggregate in internally cured concrete

    Science.gov (United States)

    Miller, Albert E.

    Early age shrinkage of cementitious systems can result in an increased potential for cracking which can lead to a reduction in service life. Early age shrinkage cracking can be particularly problematic for high strength concretes, which are often specified due to their high strength and low permeability. However, these high strength concretes frequently exhibit a reduction in the internal relative humidity (RH) due to the hydration reaction (chemical shrinkage) and self-desiccation which results in a bulk shrinkage, termed autogenous shrinkage, which is substantial at early ages. Due to the low permeability of these concretes, standard external curing is not always efficient in addressing this reduction in internal RH since the penetration of water can be limited. Internal curing has been developed to reduce autogenous shrinkage. Internally cured mixtures use internal reservoirs filled with fluid (generally water) that release this fluid at appropriate times to counteract the effects of self-desiccation thereby maintaining a high internal RH. Internally cured concrete is frequently produced in North America using pre-wetted lightweight aggregate. One important aspect associated with preparing quality internally cured concrete is being able to determine the absorbed moisture and surface moisture associated with the lightweight aggregate which enables aggregate moisture corrections to be made for the concrete mixture. This thesis represents work performed to develop a test method using a centrifuge to determine the moisture state of pre-wetted fine lightweight aggregate. The results of the test method are then used in a series of worksheets that were developed to assist field technicians when performing the tests and applying the results to a mixture design. Additionally, research was performed on superabsorbent polymers to assess their ability to be used as an internal curing reservoir.

  6. Reduction of the capillary water absorption of foamed concrete by using the porous aggregate

    Science.gov (United States)

    Namsone, E.; Sahmenko, G.; Namsone, E.; Korjakins, A.

    2017-10-01

    The article reports on the research of reduction of the capillary water absorption of foamed concrete (FC) by using the porous aggregate such as the granules of expanded glass (EG) and the cenospheres (CS). The EG granular aggregate is produced by using recycled glass and blowing agents, melted down in high temperature. The unique structure of the EG granules is obtained where the air is kept closed inside the pellet. The use of the porous aggregate in the preparation process of the FC samples provides an opportunity to improve some physical and mechanical properties of the FC, classifying it as a product of high-performance. In this research the FC samples were produced by adding the EG granules and the CS. The capillary water absorption of hardened samples has been verified. The pore size distribution has been determined by microscope. It is a very important characteristic, specifically in the cold climate territories-where temperature often falls below zero degrees. It is necessary to prevent forming of the micro sized pores in the final structure of the material as it reduces its water absorption capacity. In addition, at a below zero temperature water inside these micro sized pores can increase them by expanding the stress on their walls during the freezing process. Research of the capillary water absorption kinetics can be practical for prevision of the FC durability.

  7. Effect of Coarse Aggregate and Slag Type on the Mechanical Behavior of High and Normal Weight Concrete Used at Barrage Structure

    Directory of Open Access Journals (Sweden)

    Muhammad Sanaullah

    2017-04-01

    Full Text Available Present study is an effort to assess the composite effect of limestone aggregate and blast furnace slag on the mechanical characteristics of normal and high weight concrete at various structural units (barrage girders, main weir and block apron of New Khanki Barrage Project, Punjab. Mix designs for different concrete classes falling under the domain of high and normal weight concrete were prepared after aggregate quality testing. On attaining satisfactory results of quality testing nine concrete mixes were designed (three for each class: A1, A and B by absolute volume method (ACI- 211.1. The required compressive strength of normal and high strength was set at 6200, 5200 and 4200 Psi for the concrete types A1, A and B respectively after 28 days (ACI -318. For compressive strength assessment, a total 27 concrete cylinders were casted (9-cylinders for each mix and were water cured. The achieved average UCS of cylinder concrete specimens at 3, 7 and 28 days are 5170, 6338 and 7320 Psi for A1 – type, 3210, 4187 and 5602 Psi for A-type and 2650, 3360 and 4408 Psi for B- type mix. It has been found that all concrete mixes for suggested classes attained target strength at age of 7-days. The coarse aggregate (Margala Hill limestone and fine aggregates (from Lawrancepur /Qibla Bandi quarries used in all concrete mix designs have demonstrated a sound mechanical suitability for high and normal weight concrete.

  8. Structural Design and Economic Evaluation of Roller Compacted Concrete Pavement with Recycled Aggregates

    Science.gov (United States)

    Abut, Yavuz; Taner Yildirim, Salih

    2017-10-01

    Using recycled aggregates in the concrete offers advantages in many areas such as waste management, energy save and natural resources, conservation of ecological balance, low CO2 emissions, and users are encouraged in this regard to use these materials. In this study, the profit / loss account arising in the structural design phase was investigated when Reclaimed Asphalt Pavement (RAP), which is limited to use in Roller Compacted Concrete (RCC) pavements, was used as coarse aggregate. RAP materials were used as coarse aggregates by the levels of 0%, 15% and 20% and mechanical properties such as compressive strength, flexural strength, splitting tensile strength and modulus of elasticity were investigated. In the last stage, the mechanical properties obtained from these experimental studies were entered into KENSLABS software as input, and the slab layer thicknesses were determined according to three different subgrade conditions and a certain fatigue criterion. According to the results, it has been determined that the use of RAP at a level of 20% is a serious reducing effect on mechanical properties and and the use of RAP at a level of 15% does not bring a great economic benefit but it is reasonable to use it as coarse aggregate in RCC mixes in consideration of environmental effects.

  9. An experimental study on the hazard assessment and mechanical properties of porous concrete utilizing coal bottom ash coarse aggregate in Korea.

    Science.gov (United States)

    Park, Seung Bum; Jang, Young Il; Lee, Jun; Lee, Byung Jae

    2009-07-15

    This study evaluates quality properties and toxicity of coal bottom ash coarse aggregate and analyzes mechanical properties of porous concrete depending on mixing rates of coal bottom ash. As a result, soundness and resistance to abrasion of coal bottom ash coarse aggregate were satisfied according to the standard of coarse aggregate for concrete. To satisfy the standard pertaining to chloride content, the coarse aggregates have to be washed more than twice. In regards to the result of leaching test for coal bottom ash coarse aggregate and porous concrete produced with these coarse aggregates, it was satisfied with the environment criteria. As the mixing rate of coal bottom ash increased, influence of void ratio and permeability coefficient was very little, but compressive and flexural strength decreased. When coal bottom ash was mixed over 40%, strength decreased sharply (compressive strength: by 11.7-27.1%, flexural strength: by maximum 26.4%). Also, as the mixing rate of coal bottom ash increased, it was confirmed that test specimens were destroyed by aggregate fracture more than binder fracture and interface fracture. To utilize coal bottom ash in large quantities, it is thought that an improvement method in regards to strength has to be discussed such as incorporation of reinforcing materials and improvement of aggregate hardness.

  10. Characterization of Concrete made with Recycled Aggregate from Ceramic Sanitary Ware

    Directory of Open Access Journals (Sweden)

    Medina, C.

    2011-12-01

    Full Text Available This study examined the possibility of reusing the ceramic wastes of sanitary ware as coarse aggregate, in partial substitution (15, 20 y 25 % of natural coarse aggregates. Firstly, the characterization of recycled coarse ceramic aggregate was carried out subsequently proceeded to establish the parameters of dosage and manufacture of different concretes. Lastly, tests were conducted using these mixes to characterize physical and mechanical, and a study was carried out to identify the crystalline phases. Results showed that as the substitution proportion increased, the mechanical properties of the concrete improved, whilst physical properties remained practically constant. In view of these results, we conclude that it is possible to use this type of ceramic waste as coarse aggregate when mixing concrete destined for structural purposes.

    En este estudio se plantea la posibilidad de reutilizar los residuos cerámicos de sanitarios como árido grueso sustituyendo de forma parcial (15, 20 y 25 % al árido grueso natural. Para ello, se llevó a cabo la caracterización del árido cerámico reciclado y posteriormente se procedió a establecer los parámetros de dosificación y fabricación de los distintos hormigones. Finalmente, se realizó sobre los mismos unos ensayos de caracterización de las propiedades físicas y mecánicas, y un estudio de las fases cristalinas. Los resultados indican que a medida que se aumenta el porcentaje de sustitución se ven mejoradas las propiedades mecánicas de estos, mientras que las propiedades físicas se mantienen prácticamente constantes. A la vista de estos resultados se puede concluir que es posible la utilización de este tipo de residuo cerámico como árido grueso en la elaboración de hormigones con fines estructurales.

  11. Documentation for Calculations of Standard Fire Resistance of Slabs and Walls of Concrete with Expanded Clay Aggregate

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    A number of full-scale tests are made in order to document calculation methods for fire-exposed slabs and walls derived during a previous project on fire exposed light-weight aggregate concrete constructions. The calculation methods are derived, and thus have a logical connection with the calcula......A number of full-scale tests are made in order to document calculation methods for fire-exposed slabs and walls derived during a previous project on fire exposed light-weight aggregate concrete constructions. The calculation methods are derived, and thus have a logical connection...... with the calculation methods used for other load cases. In addition the methods are shown to be valid for heavy concrete constructions by cooperation with tests for beams and columns, and a few slabs and walls. The two test series phase 1 and 2 of this report can therefore be seen as a necessary supplement to show...... that the methods are applicable for slabs and walls of light weight aggregate concrete. It is shown that the temperatures for standard fire exposed cross sections can be calculated, that the ultimate moment capacity can be calculated for slabs, and that the anchorage capacity and the shear tension capacity can...

  12. Compressive strength of structural concrete made with locally available coarse aggregates

    International Nuclear Information System (INIS)

    Kumar, A.; Khaskheli, G.B.

    2009-01-01

    Quality of CA (Coarse Aggregate) is one of the prime factors to control the quality of concrete. But construction industry of Sindh is not very much bothered about the quality of CA in concrete manufacturing. In Sindh, Hyderabad vicinity is comparatively rich in production of CA. This research is to evaluate the compressive strength of structural concrete made with CA obtained from five different crush plants (Petaro, Parker, Palari, Ghulam Hyder Baloch and Ongar), available in the vicinity of Hyderabad. ln total 360 concrete cubes (150x150x150mm) were manufactured, 72 for each source of CA by keeping 1:2:4 and 1:1.5:3 material ratios. The cubes were manufactured with 0.45 w/c (water cement ratio), 0.5 and 0.55 w/c and tested for compressive strength after 3, 7, 14 and 28 days of curing. Results show that performance of CA obtained from all the five crush plants remained in agreement with BS and ACI Code recommendations. Concrete made with CA obtained from Petaro and Parker gave higher early strength than that of others while concrete made with CA obtained from Petaro, Parker together with Palari gave higher 28th day compressive strength. (author)

  13. Structural recycled concrete: utilization of recycled aggregate from construction and demolition wastes; Hormigon reciclado estructural: utilizacion de arido reciclado procedente de escombros de hormigon

    Energy Technology Data Exchange (ETDEWEB)

    Alaejos Gutierrez, P.; Sanchez de Juan, M.

    2015-07-01

    This paper aims to present the main results of CEDEX research works concerning the use of recycled aggregates for structural concretes. By way of conclusion, recommendations on the requirements of the recycled aggregates have been established, providing information about the influence of these aggregates on the properties of structural concrete. (Author)

  14. Experimental investigation of photocatalytic effects of concrete in air purification adopting entire concrete waste reuse model.

    Science.gov (United States)

    Xu, Yidong; Chen, Wei; Jin, Ruoyu; Shen, Jiansheng; Smallbone, Kirsty; Yan, Chunyang; Hu, Lei

    2018-07-05

    This research investigated the capacities of recycled aggregate concrete adopting entire concrete waste reuse model in degrading NO 2. Two major issues within environmental sustainability were addressed: concrete waste reuse rate and mitigation of hazards substances in the polluted air. The study consisted of two stages: identification of proper replacement rates of recycled concrete wastes in new concrete mixture design, and the evaluation of photocatalytic performance of recycled aggregate concrete in degrading NO 2 . It was found that replacement rates up to 3%, 30%, and 50% for recycled power, recycled fine aggregate, and recycled coarse aggregate respectively could be applied in concrete mixture design without deteriorating concrete strength. Recycled aggregates contained both positive attributes ("internal curing") and negative effects (e.g., lower hardness) to concrete properties. It was found that 30%-50% of natural coarse aggregate replaced by recycled coarse aggregates coated with TiO 2 would significantly improve the photocatalytic performance of concrete measured by degradation rate of NO 2 . Micro-structures of recycled aggregates observed under microscope indicated that soaking recycled aggregates in TiO 2 solution resulted in whiskers that filled the porosity within recycled aggregates which enhanced concrete strength. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Radiation shielding concrete

    International Nuclear Information System (INIS)

    Kunishima, Shigeru.

    1990-01-01

    The radiation shielding concretes comprise water, cement, fine aggregates consisting of serpentines and blown mist slags, coarse aggregates consisting of serpentines and kneading materials. Since serpentines containing a relatively great amount of water of crystallization in rocks as coarse aggregates and fine aggregates, the hydrogen content in the radiation shielding concretes is increased and the neutron shielding effect is improved. In addition, since serpentines are added as the fine aggregates and blown mists slags of a great specific gravity are used, the specific gravity of the shielding concretes is increased to improve the γ-ray shielding effect. Further, by the use of the kneading material having a water reducing effect and fluidizing effect, and by the bearing effect of the spherical blown mist slags used as the fine aggregates, concrete fluidity can be increased. Accordingly, workability of the radiation shielding concretes can be improved. (T.M.)

  16. Recycled concrete with coarse recycled aggregate. An overview and analysis

    Directory of Open Access Journals (Sweden)

    B. González-Fonteboa

    2018-04-01

    Full Text Available The construction field has contributed to environmental degradation, producing a high amount of construction and demolition waste (C&D waste and consuming large volumes of natural resources. In this context, recycled concrete (RC has been recognised as a means to preserve natural resources and reduce space for waste storage. During the last decades, many researchers have developed works studying different recycled concrete properties. This review focuses on structural RC made with coarse recycled aggregate from concrete waste. The main objective is to provide a state of the art report on RC’s properties and an analysis on how to predict them taking into account relevant research works. Moreover, the study tries to collect and update RC findings, proposing equations to define RC’s performance, in terms of mechanical strength, modulus of elasticity, stress-strain, creep and shrinkage.

  17. Review of Research on and Implementation of Recycled Concrete Aggregate in the GCC

    Directory of Open Access Journals (Sweden)

    Akmal S. Abdelfatah

    2011-01-01

    Full Text Available The goal of sustainable construction is to reduce the environmental impact of a constructed facility over its lifetime. Concrete is the main material used in construction in the Gulf Cooperation Council (GCC. Therefore, it makes economic and environmental sense to use recycled materials in the making of new concrete for different applications. The objectives of this study are to summarize published research on the use of recycled concrete aggregates in new concrete mixes and examine its implementation in construction and industry in the GCC region. The study showed that while there is reasonable research on recycled concrete, the practical implementation in the region greatly lacks behind, especially due to the lack of economic viability and awareness of such applications at the current time.

  18. Concrete density estimation by rebound hammer method

    International Nuclear Information System (INIS)

    Ismail, Mohamad Pauzi bin; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri; Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin; Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin

    2016-01-01

    Concrete is the most common and cheap material for radiation shielding. Compressive strength is the main parameter checked for determining concrete quality. However, for shielding purposes density is the parameter that needs to be considered. X- and -gamma radiations are effectively absorbed by a material with high atomic number and high density such as concrete. The high strength normally implies to higher density in concrete but this is not always true. This paper explains and discusses the correlation between rebound hammer testing and density for concrete containing hematite aggregates. A comparison is also made with normal concrete i.e. concrete containing crushed granite

  19. Mineral processing and characterization of coal waste to be used as fine aggregates for concrete paving blocks

    Directory of Open Access Journals (Sweden)

    C. R. Santos

    Full Text Available Commercial coal production in the southern region of Brazil has been occurring since the beginning of the twentieth century. Due to the geological characteristics of the region, large amounts of solid wastes are generated. The aim of this work was to evaluate the use of coal waste to produce concrete paving blocks. A procedure to process the coal waste with the purpose of reducing the sulfur content and changing the particle size distribution of the material to meet the specification of fine aggregates was developed. The methodology considered the following steps: (a sampling of a coal mining waste; (b gravity separation of the fraction with specific gravity between 2.4 and 2.8; (c comminution of the material and particle size analysis; (d technological characterization of the material and production of concrete paving blocks; and (e acidity generation prediction (environmental feasibility. The results showed that the coal waste considered in this work can be used to replace conventional sand as a fine aggregate for concrete paving blocks in a proportion of up to 50%. This practice can result in cleaner coal production and reduce the demand for exploitation of sand deposits.

  20. Feasibility of reclaimed asphalt pavement as aggregate in portland cement concrete pavement, phase II : field demonstration.

    Science.gov (United States)

    2015-10-01

    This research was focused on evaluating the feasibility of using minimally processed reclaimed asphalt pavement (RAP) as : aggregate replacement in concrete pavements. An initial phase of research demonstrated that concretes with up to 50 percent : o...

  1. Utilisation of steel furnace slag coarse aggregate in a low calcium fly ash geopolymer concrete

    International Nuclear Information System (INIS)

    Khan, M.S.H.; Castel, Arnaud; Akbarnezhad, A.; Foster, Stephen J.; Smith, Marc

    2016-01-01

    This paper evaluates the performance of steel furnace slag (SFS) coarse aggregate in blended slag and low calcium fly ash geopolymer concrete (GPC). The geopolymer binder is composed of 90% of low calcium fly ash and 10% of ground granulated blast furnace slag (GGBFS). Mechanical and physical properties, shrinkage, and detailed microstructure analysis were carried out. The results showed that geopolymer concrete with SFS aggregate offered higher compressive strength, surface resistivity and pulse velocity than that of GPC with traditional aggregate. The shrinkage results showed no expansion or swelling due to delayed calcium oxide (CaO) hydration after 320 days. No traditional porous interfacial transition zone (ITZ) was detected using scanning electron microscopy, indicating a better bond between SFS aggregate and geopolymer matrix. Energy dispersive spectroscopy results further revealed calcium (Ca) diffusion at the vicinity of ITZ. Raman spectroscopy results showed no new crystalline phase formed due to Ca diffusion. X-ray fluorescence result showed Mg diffusion from SFS aggregate towards geopolymer matrix. The incorporation of Ca and Mg into the geopolymer structure and better bond between SFS aggregate and geopolymer matrix are the most likely reasons for the higher compressive strength observed in GPC with SFS aggregate.

  2. Production of lightweight Geopolymer concrete using artificial local lightweight aggregate

    Directory of Open Access Journals (Sweden)

    Abbas Waleed

    2018-01-01

    Full Text Available Due to the rapid depletion of natural resources, the use of waste materials and by-products from different industries of building construction has been gaining increased attention. Geopolymer concrete based on Pozzolana is a new material that does not need the presence of Portland cement as a binder. The main focus of this research is to produce lightweight geopolymer concrete (LWGPC using artificial coarse lightweight aggregate which produced from locally available bentonite clays. In this investigation, the binder is low calcium fly ash (FA and the alkali activator is sodium hydroxide and sodium silicate in different molarities. The experimental tests including workability, fresh density, also, the compressive strength, splitting tensile strength, flexural strength, water absorption and ultrasonic pulse velocity at the age of 7, 28 and 56 days were studied. The oven dry density and thermal conductivity at 28 days age are investigated. The results show that it is possible to produce high strength lightweight geopolymer concrete successfully used as insulated structural lightweight concrete. The 28-day compressive strength, tensile strength, flexural strength, dry density, and thermal conductivity of the produced LWGPC are 35.8 MPa, 2.6MPa, 5.5 MPa, 1835kg/m3, and 0.9567 W/ (m. K, respectively.

  3. Recycled construction debris as an aggregates. Production of concrete blocks

    Directory of Open Access Journals (Sweden)

    Sousa, J. G. G.

    2003-12-01

    Full Text Available This paper analyzes the use of recycled construction and demolition debris as aggregate for the construction of concrete blocks to be used in sealing masonry. Initial studies addressed the definition of parameters used in the mix of conventional materials (traditionally used in the production of concrete blocks, involving cylindrical test specimens (100x200 mm, molded with the help of a vibratory table. In addition to these definitions, and based on the mixes showing the best results, a new granulometric range was established, against which the granulometry of the recycled aggregates was adjusted. After the initial studies, concrete blocks were molded with the following dimensions: 100x190x390 mm. Studies have determined the behavior of aggregates in relation to mold humidity specific mass, water absorption, and compression resistance in view of the percentage of recycled debris that composes the total aggregate. For the most part, results suggest that construction and demolition debris can potentially be used in the production of concrete blocks, as well as in other pre-molded artefacts.

    El objetivo de esta investigación es contribuir en la producción de bloques de hormigón para muros de albañilería mediante el aprovechamiento de áridos provenientes del reciclaje de residuos de la construcción civil. Los estudios preliminares tuvieron inicio con la definición de los parámetros de mezcla para los materiales convencionales (tradicionalmente utilizados en la construcción de bloques de hormigón, donde se emplearon probetas cilíndricas (100x200 mm, moldeadas con la ayuda de una mesa vibratoria. Cumplidas estas definiciones, se estableció un rango granulométrico a partir de las composiciones de mejores resultados, donde se buscó ajustar la granulometría de los áridos reciclados. Concluidos los estudios preliminares, se moldearon los bloques de hormigón con dimensiones (100x190x390 mm. Los estudios presentan como resultado el

  4. Investigation on the flexural behaviour of reinforced concrete beams using phyllite aggregates from mining waste

    International Nuclear Information System (INIS)

    Adom-Asamoah, Mark; Afrifa, Russell Owusu

    2011-01-01

    Highlights: → Most parts of the world's geology is underlain by phyllite rocks. → Crack widths not well predicted so may not be used in water retaining structures. → Shear failure mode and low displacement ductility often observed in beams. → Concrete shear capacity observed lower than code values. -- Abstract: This paper investigated the flexural behaviour of 12 reinforced concrete (RC) beams made of phyllite coarse aggregates produced as by-product of underground gold mining activity. The beams were tested to failure under four point test. Collapse of the beams which were adequately designed against shear failure occurred mostly through either flexural-shear failure and/or diagonal tension failure. The experimental failure loads averaged approximately 115% of the theoretical failure loads. It was observed that the beams developed early shear cracks and higher flexural crack widths than allowable at service loads. Deflections compared reasonably well with the design code requirement but displacement ductility was low. It is recommended that British Standard (BS) 8110 design concrete shear stress values be multiplied by 0.8 to assure that the predicted shear capacity of phyllite concrete would be low and reasonable as compared to flexural capacity. In that case, BS 8110 can be used to provide adequate load factor against flexural failure for under-reinforced RC beams made of phyllite coarse aggregates.

  5. An eco-friendly self-compacting concrete with recycled coarse aggregates

    Directory of Open Access Journals (Sweden)

    Pereira-de Oliveira, L. A.

    2013-09-01

    Full Text Available The potential uses of coarse recycled aggregates in the composition of SCC increases the ecological value and partly solve the issues of waste disposal sites generated by construction and demolition of structures. Thus, this paper present an experimental study of SCC properties where the normal coarse aggregates were replaced by different percentages of recycled aggregates, i.e., 0% (SCC, 10% (SCCR10, 20% (SCCR20, 30% (SCCR30 and 40% (SCCR40. The results from fresh concrete (rheological properties and self-compactability as the hardened concrete properties (compressive strength, density and dynamic modulus of elasticity, show only minor discrepancies. From the standpoint of mechanical behaviour, the results confirm the viability to incorporate coarse recycled aggregates in the SCC demonstrating the conservative character of the currently recommended limits.Los usos potenciales de áridos gruesos reciclados en la composición del hormigón autocompactante (SCC aumenta el valor ecológico y en parte resuelve los problemas de los sitios de disposición de residuos generados por la construcción y la demolición de las estructuras. Por lo tanto, este trabajo presenta un estudio experimental de las propiedades de SCC en el cual los áridos gruesos naturales fueron reemplazados por distintos porcentajes de áridos reciclados, es decir, 0% (SCC, el 10% (SCCR10, el 20% (SCCR20, el 30% (SCCR30 y el 40% (SCCR40. Los resultados del hormigón fresco (propiedades reológicas y la auto-compactación, como las propiedades de hormigón endurecido (resistencia a la compresión, densidad y módulo de elasticidad dinámico, muestran sólo pequeñas discrepancias. Desde el punto de vista del comportamiento mecánico, los resultados confirman la viabilidad de incorporar áridos gruesos reciclados en los SCC demostrando el carácter conservador de los límites actualmente recomendados.

  6. Fresh and mechanical properties of self-compacting concrete with coarse aggregate replacement using Waste of Oil Palm Shell

    Science.gov (United States)

    Prayuda, Hakas; Saleh, Fadillawaty; Ilham Maulana, Taufiq; Monika, Fanny

    2018-05-01

    Self-compacting Concrete (SCC) is a real innovation that can solidify itself without the help of tools to ease field practice. In its implementation, SCC can use alternative materials to reduce waste, such as Oil Palm Shell (OPS). In this research, OPS used as a replacement of crushed stone as the main coarse aggregate. The concrete mixture used consists of cement, sand, crushed stone, OPS as a variation of aggregate substitutes, palm oil fuel ash, and superplasticizer. OPS used were variated with 0%, 5%, 10%, 25% and 50% of crushed stone aggregate weight with age up to 28 days. Tests were conducted on fresh and mechanical properties. From the results, it is known that replacement of aggregate using OPS meets fresh properties criteria and although the compressive strength of OPS concrete mixture is lower than normal SCC, OPS still can be an alternative in making SCC and reducing palm oil industrial waste.

  7. Lightweight concrete with Algerian limestone dust. Part II: study on 50% and 100% replacement to normal aggregate at timely age

    Directory of Open Access Journals (Sweden)

    S. Kitouni

    2015-12-01

    Full Text Available Abstract A control lightweight concrete (LWC mixture made with 50% and 100% of limestone as a replacement of coarse aggregates in weight was prepared. Limestone is used for economical and environmental concern. The concrete samples were cured at 65% relative humidity at 20 ºC. The compressive and flexural tensile strengths, elastic modulus and Poisson's ratio of hardened concrete were measured. Laboratory compressive and tensile strength tests results showed that LWC can be produced by the use of limestone. The aim of this study is twofold: one is to design a lightweight concrete with the use of limestone that will provide an advantage of reduction in dead weight of a structure; and second is to obtain a more economical LWC mixture with the use of limestone.

  8. Overview of studies on the effect of recycled aggregates sourced from tested cylinders on concrete material and structural properties

    Directory of Open Access Journals (Sweden)

    Bilal Hamad

    2017-01-01

    Full Text Available The paper presents an overview of a two-phase research program that was designed at the American University of Beirut (AUB to investigate the effect of replacing different percentages of natural coarse aggregates (NCA with recycled coarse aggregates (RCA on the properties of the produced concrete. The source of RCA was tested cylinders in batching plants which would help recycling and reusing portion of the waste products of the concrete industry. In the first phase, the fresh and hardened mechanical properties of the produced concrete mix were investigated. The variables were the concrete strength (28 or 60 MPa and the percentage replacement of NCA with RCA from crushed tested cylinders [0 (control, 20, 40, 60, 80, or 100%. Normal strength tested cylinders were used as source of the recycled aggregates for the normal strength concrete (NSC mix and high strength tested cylinders were used for the high strength concrete (HSC mix. Tests included plastic state slump and hardened state mechanical properties including cylinder compressive strength, cylinder splitting tensile strength, modulus of elasticity, and standard beams flexural strength. The results indicated no significant effect on the slump and around 10% average reduction in the hardened mechanical properties for both investigated levels of concrete compressive strength. In the second phase, the structural behavior of normal strength concrete (NSC reinforced concrete beams prepared by replacing different percentages of NCA with RCA from tested concrete cylinders was studied. For each of three modes of failure (flexural, shear, or bond splitting, three beams with different percentages replacement [0 (control, 40, or 100 percent] were tested. One replicate was prepared for each beam to validate the test results. Results indicated no significant difference in the ultimate load reached or load-deflection behavior that could be related to the percentage replacement of NCA with RCA.

  9. The valorization of local aggregates in the manufacturing of high-performance concrete (case study of Southwest of Algeria)

    International Nuclear Information System (INIS)

    Rikioui, T.; Abdelaziz, Y.; Mekkaoui, A.

    2012-01-01

    On the basis of an experimental program to achieve an optimization of formulations of high performance concretes (HPC) based on local aggregates, a study was conducted to identify the physicochemical and mechanical properties of the aggregates locally available at the city of Bechar (southwest Algeria). A comparative estimate study between the conventional concrete and its HPC equivalent was also initiated. Finally, potential applications are commented using two practical case. (author)

  10. Utilization of fly ash as partial sand replacement in oil palm shell lightweight aggregate concrete

    Science.gov (United States)

    Nazrin Akmal, A. Z. Muhammad; Muthusamy, K.; Mat Yahaya, F.; Hanafi, H. Mohd; Nur Azzimah, Z.

    2017-11-01

    Realization on the increasing demand for river sand supply in construction sector has inspired the current research to find alternative material to reduce the use of natural sand in oil palm shell lightweight aggregate concrete (OPS LWAC) production. The existence of fly ash, a by-product generated from coal power plant, which pose negative impact to the environment when it is disposed as waste, were used in this research. The effect of fly ash content as partial sand replacement towards workability and compressive strength of OPS lightweight aggregate concrete were investigated. Four concrete mixes containing various percentage of fly ash that are 0%, 10%, 20% and 30% by weight of sand were used in the experimental work. All mixes were cast in form of cubes before subjected to water curing until the testing age. Compressive strength test were conducted at 1, 3, 7 and 28 days. The finding shows that the workability of the OPS LWAC decreases when more fly ash are used as sand replacement. It was found that adding of 10% fly ash as sand replacement content resulted in better compressive strength of OPS LWAC, which is higher than the control mix.

  11. Attenuation of Gamma Rays by Concrete . Lead Slag Composites

    International Nuclear Information System (INIS)

    Ismail, I.M.; Sweelam, M.H.; Zaghloul, Y.R.; Aly, H.F.

    2008-01-01

    Using of wastes and industrial by-products as concrete aggregate to be used as structural and radiation shielded material has increased in the recent years. Concrete was mixed with different amounts of lead slag extracted from recycling of the spent automotive batteries as fine aggregates. The lead slag was used as partial replacement of sand in the studied composites. The concrete composites obtained were characterized in terms of density, water absorption, porosity, compressive strength and attenuation of γ- rays with different energies. The attenuation coefficient and the half value thickness of the different matrices were calculated and discussed

  12. Effect of fly ash content towards Sulphate resistance of oil palm shell lightweight aggregate concrete

    Science.gov (United States)

    Muthusamy, K.; Fadzil, M. Y.; Nazrin Akmal, A. Z. Muhammad; Ahmad, S. Wan; Nur Azzimah, Z.; Hanafi, H. Mohd; Mohamad Hafizuddin, R.

    2018-04-01

    Both oil palm shell (OPS) and fly ash are by-product generated from the industries. Disposal of these by-product as wastes cause negative impact to the environment. The use of both oil palm shell and fly ash in concrete is seen as an economical solution for making green and denser concrete. The primary aim of this research is to determine the effects of FA utilization as sand replacement in oil palm shell lightweight aggregate concrete (OPS LWAC) towards sulphate resistance. Five concrete mixes containing fly ash as sand replacement namely 0%, 10%, 20%, 30% and 40% were prepared in these experimental work. All mixes were cast in form of cubes before subjected to sulphate solution for the period of 5 months. It was found that addition of 10% fly ash as sand replacement content resulted in better sulphate resistance of OPS LWAC. The occurrence of pozzolanic reaction due to the presence of FA in concrete has consumed the vulnerable Calcium hydroxide to be secondary C-S-H gel making the concrete denser and more durable.

  13. Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete

    Science.gov (United States)

    Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

    2016-01-01

    This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber—polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance. PMID:28773256

  14. Effectiveness of Fiber Reinforcement on the Mechanical Properties and Shrinkage Cracking of Recycled Fine Aggregate Concrete.

    Science.gov (United States)

    Nam, Jeongsoo; Kim, Gyuyong; Yoo, Jaechul; Choe, Gyeongcheol; Kim, Hongseop; Choi, Hyeonggil; Kim, Youngduck

    2016-02-26

    This paper presents an experimental study conducted to investigate the effect of fiber reinforcement on the mechanical properties and shrinkage cracking of recycled fine aggregate concrete (RFAC) with two types of fiber-polyvinyl alcohol (PVA) and nylon. A small fiber volume fraction, such as 0.05% or 0.1%, in RFAC with polyvinyl alcohol or nylon fibers was used for optimum efficiency in minimum quantity. Additionally, to make a comparative evaluation of the mechanical properties and shrinkage cracking, we examined natural fine aggregate concrete as well. The test results revealed that the addition of fibers and fine aggregates plays an important role in improving the mechanical performance of the investigated concrete specimens as well as controlling their cracking behavior. The mechanical properties such as compressive strength, splitting tensile strength, and flexural strength of fiber-reinforced RFAC were slightly better than those of non-fiber-reinforced RFAC. The shrinkage cracking behavior was examined using plat-ring-type and slab-type tests. The fiber-reinforced RFAC showed a greater reduction in the surface cracks than non-fiber-reinforced concrete. The addition of fibers at a small volume fraction in RFAC is more effective for drying shrinkage cracks than for improving mechanical performance.

  15. Feasibility of surface sampling in automated inspection of concrete aggregates during bulk transport on a conveyor

    NARCIS (Netherlands)

    Bakker, M.C.M.; Di Maio, F.; Lotfi, S.; Bakker, M.; Hu, M.; Vahidi, A.

    2017-01-01

    Automated optic inspection of concrete aggregates for pollutants (e.g. wood, plastics, gypsum and brick) is required to establish the suitability for reuse in new concrete products. Inspection is more efficient when directly sampling the materials on the conveyor belt instead of feeding them in a

  16. Innovative process routes for a high-quality concrete recycling in the aggregates and cement industries

    OpenAIRE

    Bru , Kathy; Menard , Yannick; Touzé , Solène; Le Moign , Alain; Poirier , Jean Eric; Ruffié , Gilles; Bonnaudin , Fabrice; Von Der Weid , Frédéric

    2011-01-01

    International audience; Hardened concrete is a composite material that contains two main phases: the matrix (hardened cement paste, 20 %) and aggregates (gravels and sand, 80 %). The liberation and the recycling of these constituents can provide an answer to i) the exploration of new aggregates supply sources imposed by the depletion of natural deposit and the faced difficulties when trying to open new quarries and ii) the reduction of CO2 emissions in the clinker manufacturing process throug...

  17. The Importance of Superplastizer Dosage in the Mix Design of Lightweight Aggregate Concrete Reinforced With Plypropylene Fiber

    Directory of Open Access Journals (Sweden)

    Shafigh Payam

    2016-01-01

    Full Text Available This paper reports the results of a study conducted to investigate the effect of superplasticizer (SP dosage on the slump, density, compressive strength and splitting tensile strength under different curing conditions of a lightweight aggregate concrete reinforced with polypropylene (PP fiber. The lightweight aggregate used in this study was oil palm shell, which is an agricultural solid waste, originating from the palm oil industry. The results indicated that an increase in superplasticizer increased the workability, however, all the mechanical properties declined significantly. The reduction in the 28-day compressive and splitting tensile strengths was about 14. This study showed that although additional SP can improve the workability of the concrete, it may have a negative effect on the other properties of concrete. Therefore, the SP dosage in concrete mixtures containing PP fiber should be limited to a certain amount.

  18. The Influence of Aggregate Size and Binder Material on the Properties of Pervious Concrete

    Directory of Open Access Journals (Sweden)

    Tun Chi Fu

    2014-01-01

    Full Text Available Specimens were prepared by altering parameters such as aggregate sizes, binder materials, and the amounts of binder used and were subsequently tested by using permeability, porosity, mechanical strength, and soundness tests. The results indicated that the water permeability coefficient and connected porosity decreased as the amount of binder used increased and increased with increasing aggregate size. In the mechanical strength test, the compressive, splitting tensile, and flexural strengths increased as the amount of binder used increased and decreased with the increase of aggregate size. Highly viscous binder enhanced compressive strength, water permeability, and the resistance to sulfate attacks. In the mechanics and sulfate soundness tests, the mix proportion of alkali-activated slag paste used in this study exhibited a superior performance than the Portland cement pervious concrete (the control did, but the difference in water permeability between the two types of concrete was insignificant. The mix proportions of cement paste containing 20% and 30% silica fume exhibited less mechanical strength than the control did. Moreover, compared with the control, the cement paste containing silica fume demonstrated poor resistance to sulfate attacks, and the difference in the water permeability between such specimen and the control was not noticeable.

  19. Improving Thermal Insulation Properties for Prefabricated Wall Components Made Of Lightweight Aggregate Concrete with Open Structure

    Science.gov (United States)

    Abramski, Marcin

    2017-10-01

    Porous concrete is commonly used in civil engineering due to its good thermal insulation properties in comparison with normal concrete and high compression strength in comparison with other building materials. Reducing of the concrete density can be obviously obtained by using lightweight aggregate (e.g. pumice). The concrete density can be further minimized by using specially graded coarse aggregate and little-to-no fine aggregates. In this way a large number of air voids arise. The aggregate particles are coated by a cement paste and bonded together with it just in contact points. Such an extremely porous concrete, called ‘lightweight aggregate concrete with open structure’ (LAC), is used in some German plants to produce prefabricated wall components. They are used mainly in hall buildings, e.g. supermarkets. The need of improving thermal insulation properties was an inspiration for the prefabrication plant managers, engineers and a scientific staff of the Technical University of Kaiserslautern / Germany to realise an interesting project. Its aim was to reduce the heat transfer coefficient for the wall components. Three different wall structure types were designed and compared in full-scale laboratory tests with originally produced wall components in terms of load-carrying capacity and stiffness. The load was applied perpendicularly to the wall plane. As the components are not originally used for load-bearing walls, but for curtain walls only, the wind load is the main load for them. The wall components were tested in horizontal position and the load was applied vertically. Totally twelve wall components 8.00 × 2.00 × 0.25m (three for every series) were produced in the prefabrication plant and tested in the University of Kaiserslautern laboratory. The designed and tested components differed from each other in the amount of expanded polystyrene (EPS), which was placed in the plant inside the wall structure. The minimal amount of it was designed in the

  20. Recycling of waste glass as a partial replacement for fine aggregate in concrete.

    Science.gov (United States)

    Ismail, Zainab Z; Al-Hashmi, Enas A

    2009-02-01

    Waste glass creates serious environmental problems, mainly due to the inconsistency of waste glass streams. With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal. The properties of concretes containing waste glass as fine aggregate were investigated in this study. The strength properties and ASR expansion were analyzed in terms of waste glass content. An overall quantity of 80 kg of crushed waste glass was used as a partial replacement for sand at 10%, 15%, and 20% with 900 kg of concrete mixes. The results proved 80% pozzolanic strength activity given by waste glass after 28 days. The flexural strength and compressive strength of specimens with 20% waste glass content were 10.99% and 4.23%, respectively, higher than those of the control specimen at 28 days. The mortar bar tests demonstrated that the finely crushed waste glass helped reduce expansion by 66% as compared with the control mix.

  1. Carbonated miscanthus mineralized aggregates for reducing environmental impact of lightweight concrete blocks

    Directory of Open Access Journals (Sweden)

    Courard Luc

    2017-01-01

    Full Text Available At a time when the cement industry is largely responsible for the production of CO2 in the construction sector, it is useful to make this production a reverse phenomenon: that is CO2 capture. The CO2 absorption process called carbonation, improves specific properties of the concrete during the conversion of carbon dioxide CO2 into calcium carbonate CaCO3. Current environmental concerns motivate the study of carbonation in order to maximize the absorption of carbon dioxide. Moreover, lightweight concrete with bio-based products knows an interesting development in the construction field, especially as thermal insulation panels for walls in buildings. Before identifying and quantifying the basic physical characteristics of concrete made from miscanthus, it is necessary to optimize the composition of the product. The long-term stability as well as the reinforcement may be obtained by means of a mineralization process of the natural product: a preparation with a lime and/or cement-based material is necessary to reinforce the cohesion of the bio-based product. Mineralization process is described as well as the way of producing blocks for CO2 capture by means of accelerated carbonation. Finally, concrete blocks produced with miscanthus mineralized aggregates offer interesting mechanical properties and minimal environmental impact.

  2. Study of local Agregate for Gamma radiation concrete shield

    International Nuclear Information System (INIS)

    Tochrul-Binowo; Endro-Kismolo; Darsono

    1996-01-01

    Investigation on the composition of gamma radiation concrete shield made of local barite, manganese fine and coarse aggregates from Kulon Progo, Yogyakarta has been done. The purpose of the research was to find out the quality of these local material for an aggregate of gamma radiation concrete shield. The research was done where each mineral was used as coarse aggregate and the fine aggregate from Kulon Progo was used as fine basic aggregate. Firstly a normal concrete was made by mixing cement, fine aggregate, coarse aggregate and water at a weight ratio of cement: fine aggregate: coarse: water 1: 2.304: 3.456: 0.58. The gamma radiation absorption capacity of the concrete tested by using Cs-137 as source standard. The same method was done on barite concrete at the weight ratio of cement: fine aggregate: barite aggregate: water 1: 2.303: 3.456: 0.58 and manganese concrete at the weight ratio of cement: fine aggregate: manganese aggregate: and water 1: 1.896: 2.844: 0.58. The result of the study showed that the gamma radiation absorption capacity of barite aggregate was greater than that of normal concrete and manganese concrete. The coefficient linear attenuation (for 6.0 cm thickness) of each concrete were μ barite concrete = 0.23071 cm -1 , μ manganese concrete = 0.08401 cm -1 and μ normal concrete = 0.1669 cm -1

  3. Standard test method for compressive strength of grouts for preplaced-aggregate concrete in the laboratory. ASTM standard

    International Nuclear Information System (INIS)

    1998-10-01

    DoD adopted. This test method is under the jurisdiction of ASTM Committee C-9 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.41 on Concrete for Radiation Shielding. Current edition approved Feb. 10, 1986 and published October 1998. Originally published as C 942-81. Last previous edition was C 942-86(1991)

  4. The mechanical properties of brick containing recycled concrete aggregate and polyethylene terephthalate waste as sand replacement

    Science.gov (United States)

    Sheikh Khalid, Faisal; Bazilah Azmi, Nurul; Natasya Mazenan, Puteri; Shahidan, Shahiron; Ali, Noorwirdawati

    2018-03-01

    This research focuses on the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. This study aims to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate (RCA) and polyethylene terephthalate (PET) waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 0.5%, 1.0% and 1.5% by weight of natural sand. Based on the results of compressive strength, only RCA 25% with 0.5% PET achieve lower strength than normal bricks while others showed a high strength. However, all design mix reaches strength more than 7N/mm2 as expected. Besides that, the most favorable mix design that achieves high compressive strength is 75% of RCA with 0.5% PET.

  5. Bond-Slip Relationship for CFRP Sheets Externally Bonded to Concrete under Cyclic Loading.

    Science.gov (United States)

    Li, Ke; Cao, Shuangyin; Yang, Yue; Zhu, Juntao

    2018-02-26

    The objective of this paper was to explore the bond-slip relationship between carbon fiber-reinforced polymer (CFRP) sheets and concrete under cyclic loading through experimental and analytical approaches. Modified beam tests were performed in order to gain insight into the bond-slip relationship under static and cyclic loading. The test variables are the CFRP-to-concrete width ratio, and the bond length of the CFRP sheets. An analysis of the test results in this paper and existing test results indicated that the slope of the ascending segment of the bond-slip curve decreased with an increase in the number of load cycles, but the slip corresponding to the maximum shear stress was almost invariable as the number of load cycles increased. In addition, the rate of reduction in the slope of the ascending range of the bond-slip curve during cyclic loading decreased as the concrete strength increased, and increased as the load level or CFRP-to-concrete width ratio enhanced. However, these were not affected by variations in bond length if the residual bond length was longer than the effective bond length. A bilinear bond-slip model for CFRP sheets that are externally bonded to concrete under cyclic loading, which considered the effects of the cyclic load level, concrete strength, and CFRP-to-concrete ratio, was developed based on the existing static bond-slip model. The accuracy of this proposed model was verified by a comparison between this proposed model and test results.

  6. Bond–Slip Relationship for CFRP Sheets Externally Bonded to Concrete under Cyclic Loading

    Science.gov (United States)

    Li, Ke; Cao, Shuangyin; Yang, Yue; Zhu, Juntao

    2018-01-01

    The objective of this paper was to explore the bond–slip relationship between carbon fiber-reinforced polymer (CFRP) sheets and concrete under cyclic loading through experimental and analytical approaches. Modified beam tests were performed in order to gain insight into the bond–slip relationship under static and cyclic loading. The test variables are the CFRP-to-concrete width ratio, and the bond length of the CFRP sheets. An analysis of the test results in this paper and existing test results indicated that the slope of the ascending segment of the bond–slip curve decreased with an increase in the number of load cycles, but the slip corresponding to the maximum shear stress was almost invariable as the number of load cycles increased. In addition, the rate of reduction in the slope of the ascending range of the bond–slip curve during cyclic loading decreased as the concrete strength increased, and increased as the load level or CFRP-to-concrete width ratio enhanced. However, these were not affected by variations in bond length if the residual bond length was longer than the effective bond length. A bilinear bond–slip model for CFRP sheets that are externally bonded to concrete under cyclic loading, which considered the effects of the cyclic load level, concrete strength, and CFRP-to-concrete ratio, was developed based on the existing static bond–slip model. The accuracy of this proposed model was verified by a comparison between this proposed model and test results. PMID:29495383

  7. Use of plastic waste (poly-ethylene terephthalate) in asphalt concrete mixture as aggregate replacement.

    Science.gov (United States)

    Hassani, Abolfazl; Ganjidoust, Hossein; Maghanaki, Amir Abedin

    2005-08-01

    One of the environmental issues in most regions of Iran is the large number of bottles made from poly-ethylene terephthalate (PET) deposited in domestic wastes and landfills. Due to the high volume of these bottles, more than 1 million m3 landfill space is needed for disposal every year. The purpose of this experimental study was to investigate the possibility of using PET waste in asphalt concrete mixes as aggregate replacement (Plastiphalt) to reduce the environmental effects of PET disposal. For this purpose the mechanical properties of plastiphalt mixes were compared with control samples. This study focused on the parameters of Marshall stability, flow, Marshall quotient (stability-to-flow ratio) and density. The waste PET used in this study was in the form of granules of about 3 mm diameter which would replace (by volume) a portion of the mineral coarse aggregates of an equal size (2.36-4.75 mm). In all prepared mixes the determined 6.6% optimum bitumen content was used. In this investigation, five different percentages of coarse aggregate replacement were used. The results showed that the aggregate replacement of 20% by volume with PET granules would result in a reduction of 2.8% in bulk compacted mix density. The value of flow in the plastiphalt mix was lower than that of the control samples. The results also showed that when PET was used as partial aggregate replacement, the corresponding Marshall stability and Marshall quotient were almost the same as for the control samples. According to most of specification requirement, these results introduce an asphalt mix that has properties that makes it suitable for practical use and furthermore, the recycling of PET for asphalt concrete roads helps alleviate an environmental problem and saves energy.

  8. Performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate with different mix design ratio

    Science.gov (United States)

    Azmi, N. B.; Khalid, F. S.; Irwan, J. M.; Mazenan, P. N.; Zahir, Z.; Shahidan, S.

    2018-04-01

    This study is focuses to the performance of composite sand cement brick containing recycle concrete aggregate and waste polyethylene terephthalate. The objective is to determine the mechanical properties such as compressive strength and water absorption of composite brick containing recycled concrete aggregate and polyethylene terephthalate waste and to determine the optimum mix ratio of bricks containing recycled concrete aggregate and polyethylene terephthalate waste. The bricks specimens were prepared by using 100% natural sand, they were then replaced by RCA at 25%, 50% and 75% with proportions of PET consists of 1.0%, 1.5%, 2.0% and 2.5% by weight of natural sand. Based on the results of compressive strength, it indicates that the replacement of RCA shows an increasing strength as the strength starts to increase from 25% to 50% for both mix design ratio. The strength for RCA 75% volume of replacement started to decrease as the volume of PET increase. However, the result of water absorption with 50% RCA and 1.0% PET show less permeable compared to control brick at both mix design ratio. Thus, one would expect the density of brick decrease and the water absorption to increase as the RCA and PET content is increased.

  9. Properties of Concrete Paving Blocks and Hollow Tiles with Recycled Aggregate from Construction and Demolition Wastes.

    Science.gov (United States)

    Rodríguez, Carlos; Miñano, Isabel; Aguilar, Miguel Ángel; Ortega, José Marcos; Parra, Carlos; Sánchez, Isidro

    2017-11-30

    In recent years there has been an increasing tendency to recycle the wastes generated by building companies in the construction industry, demolition wastes being the most important in terms of volume. The aim of this work is to study the possibility of using recycled aggregates from construction and demolition wastes in the preparation of precast non-structural concretes. To that purpose, two different percentages (15% and 30%) of natural aggregates were substituted by recycled aggregates in the manufacture of paving blocks and hollow tiles. Dosages used by the company have not been changed by the introduction of recycled aggregate. Precast elements have been tested by means of compressive and flexural strength, water absorption, density, abrasion, and slipping resistance. The results obtained show the possibility of using these wastes at an industrial scale, satisfying the requirements of the Spanish standards for these elements.

  10. TRANSPARENT CONCRETE

    OpenAIRE

    Sandeep Sharma*, Dr. O.P. Reddy

    2017-01-01

    Transparent concrete is the new type of concrete introduced in todays world which carries special property of light transmitting due to presence of light Optical fibres. Which is also known as translucent concrete or light transmitting concrete, it is achieved by replacing coarse aggregates with transparent alternate materials (Optical fibres). The binding material in transparent concrete may be able to transmit light by using clear resins the concrete mix. The concrete used in industry in pr...

  11. Recycled concrete aggregate as road base: Leaching constituents and neutralization by soil Interactions and dilution.

    Science.gov (United States)

    Gupta, Nautasha; Kluge, Matt; Chadik, Paul A; Townsend, Timothy G

    2018-02-01

    Recycled Concrete Aggregate (RCA) is often used as a replacement for natural aggregate in road construction activities because of its excellent mechanical properties, and this trend should increase as more transportation departments include RCA in specifications and design manuals. Concerns raised by some engineers and contractors include impacts from leachate generated by RCA, both from transport of metals to water sources and the impact of a high pH leachate on corrosion of underlying metal drainage pipes. In this study, RCA collected from various regions of Florida exhibited pH ranging from 10.5 to 12.3. Concentrations of Al, Ba, Cr, Fe, Mo, Na, Ni, Sb, and Sr measured using batch leaching tests exceeded applicable risk-based thresholds on at least some occasions, but the concentrations measured suggest that risk to water supplies should be controlled because of dilution and attenuation. Two mechanisms of pH neutralization were evaluated. Soil acidity plays a role, but laboratory testing and chemical modeling found that at higher liquid-to-solid ratios the acidity is exhausted. If high pH leachate did reach groundwater, chemical modeling indicated that groundwater dilution and carbonation would mitigate groundwater pH effects. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Life Cycle Analysis of High Quality Recycled Aggregate Produced byHeating and Rubbing Method

    Science.gov (United States)

    Shima, Hirokazu; Matsuhashi, Ryuji; Yoshida, Yoshikuni; Tateyashiki, Hisashi

    Most of demolished concrete is recycled as road subbase, but its generation is expected to increase rapidly and exceed the demand of road subbase in a near future. To promote the recycling of concrete, the technology to produce high quality recycled aggregate by the heating and rubbing method has been developed. In this method, demolished concrete is heated up to about 300°C in a heater to make cement paste brittle with its dehydration. The heated concrete is then rubbed in two mills to recover the recycled aggregate, while the paste is removed from the surface of aggregate and collected as cement fine powder. In this method, much energy is consumed to heat and rub concrete; however, the cement fine powder is utilized for a soil stabilizer and cement raw materials, so that the environmental load is reduced in cement manufacturing. The life cycle analysis of the recycled aggregate is carried out to evaluate this technology. As a result, the life cycle CO2 is a negative value because the deduction of CO2 emission in cement manufacturing by the powder is much large. This technology is proved to be very effective to reduce CO2.

  13. Utilization of Construction Waste Tiles as a Replacement for Fine Aggregates in Concrete

    Directory of Open Access Journals (Sweden)

    A. A. Adekunle

    2017-10-01

    Full Text Available Ceramic wastes are found to be suitable for usage as substitution for fine and coarse aggregates in concrete production. This study is an investigation into the utilization of waste tiles as partial replacement for fine and coarse aggregates in concrete. The control mix and other mixes containing cement, water, granite and partial replacement for sand with crushed tiles (in 5%, 10%, 15% and 20% proportions were cast, cubed, cured and crushed. Also, another mix containing cement, water, sand and partial replacement of granite with crushed tiles (in 25%, 50% and 75% proportions were cast, cubed, cured and crushed. The specimens were tested for their respective compressive strengths using the Universal Testing Machine (UTM on the 7th, 14th, 21st and 28th days of curing. At 28 days, the compressive strength value of 5% of fine-waste tiles replacement was 20.12 N/mm2 while that of 10%, 15% and 20% were 14.24 N/mm2, 11.04 N/mm2 and 10.12 N/mm2 respectively. Moreover, at 28 days, the compressive strength of 25% of coarse-waste tiles replacement shows an increase to 22.45 N/mm2 while that of 50% and 75% were 18.4 N/mm2 and 12.2 N/mm2 respectively. Thus it can be concluded that fine aggregates can be substituted at 5% waste tiles while coarse aggregates can be substituted at 25% waste tiles.>/p>

  14. Properties of Concrete Paving Blocks and Hollow Tiles with Recycled Aggregate from Construction and Demolition Wastes

    Directory of Open Access Journals (Sweden)

    Carlos Rodríguez

    2017-11-01

    Full Text Available In recent years there has been an increasing tendency to recycle the wastes generated by building companies in the construction industry, demolition wastes being the most important in terms of volume. The aim of this work is to study the possibility of using recycled aggregates from construction and demolition wastes in the preparation of precast non-structural concretes. To that purpose, two different percentages (15% and 30% of natural aggregates were substituted by recycled aggregates in the manufacture of paving blocks and hollow tiles. Dosages used by the company have not been changed by the introduction of recycled aggregate. Precast elements have been tested by means of compressive and flexural strength, water absorption, density, abrasion, and slipping resistance. The results obtained show the possibility of using these wastes at an industrial scale, satisfying the requirements of the Spanish standards for these elements.

  15. Effect of palm oil fuel ash on compressive strength of palm oil boiler stone lightweight aggregate concrete

    Science.gov (United States)

    Muthusamy, K.; Zamri, N. A.; Kusbiantoro, A.; Lim, N. H. A. S.; Ariffin, M. A. Mohd

    2018-04-01

    Both palm oil fuel ash (POFA) and palm oil boiler stone (POBS) are by-products which has been continuously generated by local palm oil mill in large amount. Both by products is usually disposed as profitless waste and considered as nuisance to environment. The present research investigates the workability and compressive strength performance of lightweight aggregate concrete (LWAC) made of palm oil boiler stone (POBS) known as palm oil boiler stone lightweight aggregate concrete (POBS LWAC) containing various content of palm oil fuel ash. The control specimen that is POBS LWAC of grade 60 were produced using 100% OPC. Then, another 4 mixes were prepared by varying the POFA percentage from 10%, 20%, 30% and 40% by weight of cement. Fresh mixes were subjected to slump test to determine its workability before casted in form of cubes. Then, all specimens were subjected to water curing up to 28 days and then tested for its compressive strength. It was found out that utilizing of optimum amount of POFA in POBS LWAC would improve the workability and compressive strength of the concrete. However, inclusion of POFA more than optimum amount is not recommended as it will increase the water demand leading to lower workability and strength reduction.

  16. Caracterización morfológica de agregados para concreto mediante el análisis de imágenes Morphological characterization of concrete aggregates by means of image analysis

    Directory of Open Access Journals (Sweden)

    Maria Patricia León

    2010-08-01

    Full Text Available La morfología de los agregados influye en las propiedades del concreto en estado fresco y endurecido, sin embargo no se ha establecido una correlación entre parámetros de forma y características del concreto de manera que la incidencia de la forma sea tenida en cuenta en el diseño de la mezcla. La medición de la forma por los métodos tradicionales es subjetiva, por esta razón últimamente se han utilizado tecnologías de análisis de imágenes para determinar las características de forma de las partículas. En este estudio se determinaron las características morfológicas de diferentes agregados usando los métodos tradicionales y el de análisis de imágenes con los descriptores de Fourier, y se determinaron las propiedades mecánicas de concreto preparado con agregados de diferente forma con el fin de evaluar la influencia de esta en las propiedades del concreto fresco y endurecido. Los resultados indican que las propiedades mecánicas no se ven afectadas de manera importante por la forma de los agregados, sin embargo, influye significativamente en la trabajabilidad.Properties of fresh and hardened concrete are affected by the morphological characteristics of the aggregates. However, there is not an established correlation, between the aggregate shape and the concrete properties, to be taken into account during the mix design process. Conventional aggregate shape measurement methods are subjective, and that is why image analysis has been recently used to determine the morphological characteristics of particles. In this study, the morphological characteristics of coarse aggregates from two different sources are determined using both, conventional methods and image analysis by means of Fourier descriptors. Mechanical properties of concrete prepared with coarse aggregates having different elongation indexes were evaluated. Results indicate that the aggregate shape has little influence in the concrete compressive strength and elastic

  17. Relation of expansion due to alkali silica reaction to the degree of reaction measured by SEM image analysis

    International Nuclear Information System (INIS)

    Haha, M. Ben; Gallucci, E.; Guidoum, A.; Scrivener, K.L.

    2007-01-01

    Scanning Electron Microscopy Image Analysis (SEM-IA) was used to quantify the degree of alkali silica reaction in affected microbars, mortar and concrete prisms. It was found that the degree of reaction gave a unique correlation with the macroscopic expansion for three different aggregates, stored at three temperatures and with two levels of alkali. The relationships found for the concretes and the mortars overlap when normalised by the aggregate content. This relationship seems to be linear up to a critical reaction degree which coincides with crack initiation within the reactive aggregates

  18. Effects of Magnetite Aggregate and Steel Powder on Thermal Conductivity and Porosity in Concrete for Nuclear Power Plant

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2016-01-01

    Full Text Available Among many engineering advantages in concrete, low thermal conductivity is an attractive property. Concrete has been widely used for nuclear vessels and plant facilities for its excellent radiation shielding. The heat isolation through low thermal conductivity is actually positive for nuclear power plant concrete; however the property may cause adverse effect when fires and melt-down occur in nuclear vessel since cooling down from outer surface is almost impossible due to very low thermal conductivity. If concrete containing atomic reactor has higher thermal conductivity, the explosion risk of conductive may be partially reduced. This paper presents high thermally conductive concrete development. For the work, magnetite with varying replacements of normal aggregates and steel powder of 1.5% of volume are considered, and the equivalent thermal conductivity is evaluated. Only when the replacement ratio goes up to 30%, thermal conductivity increases rapidly to 2.5 times. Addition of steel powder is evaluated to be effective by 1.08~1.15 times. In order to evaluate the improvement of thermal conductivity, several models like ACI, DEMM, and MEM are studied, and their results are compared with test results. In the present work, the effects of steel powder and magnetite aggregate are studied not only for strength development but also for thermal behavior based on porosity.

  19. In-plane Shear Joint Capacity of Pracast Lightweight Aggregate Concrete Elements

    DEFF Research Database (Denmark)

    Larsen, Henning; Goltermann, Per; Scherfig, Søren

    1996-01-01

    The paper establishes and documents formulas for the in-plane shear capacity between precast elements of lightweight aggregate concrete with open structure. The joints investigated are rough or toothed and have all been precracked prior to the testing in order to obtain realistic test results....... The paper documents the shear force capacity for the joint strength between the most common joint types between precast LAC roof and floor elements used in Scandinavia....

  20. Properties of concrete containing foamed concrete block waste as fine aggregate replacement

    Science.gov (United States)

    Muthusamy, K.; Budiea, A. M. A.; Zaidan, A. L. F.; Rasid, M. H.; Hazimmah, D. S.

    2017-11-01

    Environmental degradation due to excessive sand mining dumping at certain places and disposal of foamed concrete block waste from lightweight concrete producing industry are issues that should be resolved for a better and cleaner environment of the community. Thus, the main intention of this study is to investigate the potential of foamed concrete block waste as partial sand replacement in concrete production. The foamed concrete waste (FCW) used in this research that were supplied by a local lightweight concrete producing industry. The workability and compressive strength of concrete containing various percentage of foamed concrete waste as partial sand replacement has been investigated. Prior to the use, the foamed concrete waste were crushed to produce finer particles. Six concrete mixes containing various content of crushed foamed concrete waste that are 0%, 10%, 20%, 30%, 40% and 50% were used in this experimental work. Then the prepared specimens were placed in water curing until the testing age. Compressive strength test and flexural strength tests were conducted at 7, 14 and 28 days. The result shows that integration of crushed foamed concrete waste as partial sand replacement in concrete reduces the mix workability. It is interesting to note that both compressive strength and flexural strength of concrete improves when 30% crushed foamed concrete waste is added as partial sand replacement.

  1. Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products.

    Science.gov (United States)

    Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

    2015-12-25

    Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete's water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction.

  2. Effect of Using Porcelanite as Partial Replacement of Fine Aggregate on Roller Compacted Concrete with Different Curing Methods

    Directory of Open Access Journals (Sweden)

    Abeer Abdulqader Salih

    2016-09-01

    Full Text Available Roller-Compacted Concrete is a no-slump concrete, with no reinforcing steel, no forms, no finishing and wet enough to support compaction by vibratory rollers. Due to the effect of curing on properties and durability of concrete, the main purpose of this research is to study the effect of various curing methods (air curing, 7 days water curing, and permanent water curing and porcelanite (local material used as an Internal Curing agent with different replacement percentages of fine aggregate (volumetric replacement on some properties of Roller-Compacted Concrete and to explore the possibility of introducing practical Roller-Compacted Concrete for road pavement with minimum requirement of curing. Specimens were sawed from slabs of (380*380*100 mm for determination of Ultrasonic Pulse Velocity (UPV and Voids volume. Results show that using (5 % porcelanite improved the results of UPV and Voids volume of Roller-Compacted Concrete (with air curing as compared with reference Roller-Compacted Concrete (with permanent water curing by percentages ranging from(3.6 to 28.9% and (-8 to -15.5% respectively.

  3. Aggregate-cement paste transition zone properties affecting the salt-frost damage of high-performance concretes

    International Nuclear Information System (INIS)

    Cwirzen, Andrzej; Penttala, Vesa

    2005-01-01

    The influence of the cement paste-aggregate interfacial transition zone (ITZ) on the frost durability of high-performance silica fume concrete (HPSFC) has been studied. Investigation was carried out on eight non-air-entrained concretes having water-to-binder (W/B) ratios of 0.3, 0.35 and 0.42 and different additions of condensed silica fume. Studies on the microstructure and composition of the cement paste have been made by means of environmental scanning electron microscope (ESEM)-BSE, ESEM-EDX and mercury intrusion porosimetry (MIP) analysis. The results showed that the transition zone initiates and accelerates damaging mechanisms by enhancing movement of the pore solution within the concrete during freezing and thawing cycles. Cracks filled with ettringite were primarily formed in the ITZ. The test concretes having good frost-deicing salt durability featured a narrow transition zone and a decreased Ca/Si atomic ratio in the transition zone compared to the bulk cement paste. Moderate additions of silica fume seemed to densify the microstructure of the ITZ

  4. Mechanisms of Phosphorus Removal by Recycled Crushed Concrete.

    Science.gov (United States)

    Deng, Yihuan; Wheatley, Andrew

    2018-02-17

    Due to urbanisation, there are large amounts of waste concrete, particularly in rapidly industrialising countries. Currently, demolished concrete is mainly recycled as aggregate for reconstruction. This study has shown that larger sizes (2-5 mm) of recycled concrete aggregate (RCA) removed more than 90% of P from effluent when at pH 5. Analysis of the data, using equilibrium models, indicated a best fit with the Langmuir which predicated an adsorption capacity of 6.88 mg/g. Kinetic analysis indicated the equilibrium adsorption time was 12 h, with pseudo second-order as the best fit. The thermal dynamic tests showed that the adsorption was spontaneous and, together with the evidence from the sequential extraction and desorption experiments, indicated the initial mechanism was physical attraction to the surface followed by chemical reactions which prevented re-release. These results suggested that RCA could be used for both wastewater treatment and P recovery.

  5. Concrete aggregate durability study.

    Science.gov (United States)

    2009-06-01

    There are many factors that affect the durability of Portland cement concrete (PCC), including the mix design and the : materials used, the quality of construction, and the environment. Durability is not an intrinsic property of the concrete, but : i...

  6. High Strength Lightweight Concrete Made with Ternary Mixtures of Cement-Fly Ash-Silica Fume and Scoria as Aggregate

    OpenAIRE

    YAŞAR, Ergül; ATIŞ, Cengiz Duran; KILIÇ, Alaettin

    2014-01-01

    This paper presents part of the results of an ongoing laboratory study carried out to design a structural lightweight high strength concrete (SLWHSC) made with and without ternary mixtures of cement-fly ash-silica fume. In the mixtures, lightweight basaltic-pumice (scoria) aggregate was used. A concrete mixture made with lightweight scoria, and another lightweight scoria concrete mixture incorporating 20% fly ash and 10% silica fume as a cement replacement, were prepared. Two normal...

  7. EAF Slag Aggregate in Roller-Compacted Concrete Pavement: Effects of Delay in Compaction

    Directory of Open Access Journals (Sweden)

    My Ngoc-Tra Lam

    2018-04-01

    Full Text Available This study investigates the effect of delay in compaction on the optimum moisture content and the mechanical propertie s (i.e., compressive strength, ultrasonic pulse velocity, splitting tensile strength, and modulus of elasticity of roller-compacted concrete pavement (RCCP made of electric arc furnace (EAF slag aggregate. EAF slag with size in the range of 4.75–19 mm was used to replace natural coarse aggregate in RCCP mixtures. A new mixing method was proposed for RCCP using EAF slag aggregate. The optimum moisture content of RCCP mixtures in this study was determined by a soil compaction method. The Proctor test assessed the optimum moisture content of mixtures at various time after mixing completion (i.e., 0, 15, 30, 60, and 90 min. Then, the effect of delay in compaction on the mechanical properties of RCCP mixtures at 28 days of age containing EAF slag aggregate was studied. The results presented that the negative effect on water content in the mixture caused by the higher water absorption characteristic of EAF slag was mitigated by the new mixing method. The optimum water content and maximum dry density of RCCP experience almost no effect from the delay in compaction. The compressive strength and splitting tensile strength of RCCP using EAF slag aggregate fulfilled the strength requirements for pavement with 90 min of delay in compaction.

  8. Impact of Aggregates Size and Fibers on basic Mechanical Properties of Asphalt Emulsion—Cement Concrete

    Science.gov (United States)

    Fu, Jun; Liu, Zhihong; Liu, Jie

    2018-01-01

    Asphalt Emulsion—Cement Concrete (AECC) is currently considered as a typical semi-flexibility material. One of the disadvantages of this material is brittle fracture and lacking ductility. This study aims at accelerating the basic mechanical properties of AECC using fibers and different aggregates size. The mix of AECC was introduced and the different content of fibers and aggregates size were studied. The results showed that the smaller aggregates size could improve the young’s modulus and compressive strength as well as fiber. The modulus-compressive strength ratio of fiber reinforced AECC is always below 500.

  9. Experimental and numerical modeling of chloride diffusivity in hardened cement concrete considering the aggregate shapes and exposure-duration effects

    Directory of Open Access Journals (Sweden)

    Wu Jie

    Full Text Available This paper presents an experimental and numerical model describing the effects of the aggregate shapes and exposure duration of chloride diffusion into cement-based materials. A simple chloride diffusion test was performed on a concrete specimen composed of a mixture of cement mortar with crushed granites and round gravels. A simulation was done and the numerical model developed was applied to the matrix at the meso-scale level and the chloride diffusivity was investigated at 30, 60, and 90 days. The experimental and simulation results showed that the aggregate shape and the exposure duration of chloride diffusing into concrete are of high significance. It was indicated that the model with crushed granite presents a good resistance against chloride ingress, while the model with rounded gravels shows some sensitivity to the chloride penetration. It was also found out that when the time dependence of the diffusion coefficient is not taken into account, the diffusion rate will be overestimated. The meso-scale model developed in this study also provides a new method applied in the analysis of the chloride and water transport that causes damage to concrete considering the particle inclusion and the diffusion duration. Keywords: Meso-scale modeling, Chloride diffusivity, Concrete, Effects of aggregates shape and exposure duration, FEM

  10. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

    Directory of Open Access Journals (Sweden)

    Wenchao Liu

    2016-03-01

    Full Text Available The seismic performance of recycled aggregate concrete (RAC composite shear walls with different expandable polystyrene (EPS configurations was investigated. Six concrete shear walls were designed and tested under cyclic loading to evaluate the effect of fine RAC in designing earthquake-resistant structures. Three of the six specimens were used to construct mid-rise walls with a shear-span ratio of 1.5, and the other three specimens were used to construct low-rise walls with a shear-span ratio of 0.8. The mid-rise and low-rise shear walls consisted of an ordinary recycled concrete shear wall, a composite wall with fine aggregate concrete (FAC protective layer (EPS modules as the external insulation layer, and a composite wall with sandwiched EPS modules as the insulation layer. Several parameters obtained from the experimental results were compared and analyzed, including the load-bearing capacity, stiffness, ductility, energy dissipation, and failure characteristics of the specimens. The calculation formula of load-bearing capacity was obtained by considering the effect of FAC on composite shear walls as the protective layer. The damage process of the specimen was simulated using the ABAQUS Software, and the results agreed quite well with those obtained from the experiments. The results show that the seismic resistance behavior of the EPS module composite for shear walls performed better than ordinary recycled concrete for shear walls. Shear walls with sandwiched EPS modules had a better seismic performance than those with EPS modules lying outside. Although the FAC protective layer slightly improved the seismic performance of the structure, it undoubtedly slowed down the speed of crack formation and the stiffness degradation of the walls.

  11. Recycling of rubble from building demolition for low-shrinkage concretes.

    Science.gov (United States)

    Corinaldesi, Valeria; Moriconi, Giacomo

    2010-04-01

    In this project concrete mixtures were prepared that were characterized by low ductility due to desiccation by using debris from building demolition, which after a suitable treatment was used as aggregate for partial replacement of natural aggregates. The recycled aggregate used came from a recycling plant, in which rubble from building demolition was selected, crushed, cleaned, sieved, and graded. Such aggregates are known to be more porous as indicated by the Saturated Surface Dry (SSD) moisture content. The recycled concrete used as aggregates were added to the concrete mixture in order to study their influence on the fresh and hardened concrete properties. They were added either after water pre-soaking or in dry condition, in order to evaluate the influence of moisture in aggregates on the performance of concrete containing recycled aggregate. In particular, the effect of internal curing, due to the use of such aggregates, was studied. Concrete behavior due to desiccation under dehydration was studied by means of both drying shrinkage test and German angle test, through which shrinkage under the restrained condition of early age concrete can be evaluated. Copyright 2009 Elsevier Ltd. All rights reserved.

  12. Estimation of air void and aggregate spatial distributions in concrete under uniaxial compression using computer tomography scanning

    International Nuclear Information System (INIS)

    Wong, R.C.K.; Chau, K.T.

    2005-01-01

    Normal- and high-strength concrete cylinders (designed compressive strengths of 30 and 90 MPa at 28 days) were loaded uniaxially. Computer tomography (CT) scanning technique was used to examine the evolution of air voids inside the specimens at various loading states up to 85% of the ultimate compressive strength. The normal-strength concrete yielded a very different behaviour in changes of internal microstructure as compared to the high-strength concrete. There were significant instances of nucleation and growth in air voids in the normal-strength concrete specimen, while the increase in air voids in the high-strength concrete specimen was insignificant. In addition, CT images were used for mapping the aggregate spatial distributions within the specimens. No intrinsic anisotropy was detected from the fabric analysis

  13. Release of major elements from recycled concrete aggregates and geochemical modelling

    International Nuclear Information System (INIS)

    Engelsen, Christian J.; Sloot, Hans A. van der; Wibetoe, Grethe; Petkovic, Gordana; Stoltenberg-Hansson, Erik; Lund, Walter

    2009-01-01

    The pH dependent leaching characteristics were assessed for different types of recycled concrete aggregates, including real construction debris and crushed fresh concrete samples prepared in laboratory. Carbonation effects were identified from the characteristic pH dependent leaching patterns for the major constituents Al, Ca, Fe, Mg, Si and SO 4 2- . The original particle size ranges were different for the samples investigated and this factor influenced the cement paste content in the samples which in turn controlled the leachable contents. Cement paste contents for concrete samples with fine particle size fractions (0-4 mm) were found to be higher than the originally present amount in the hardened concrete. Geochemical speciation modelling was applied over the entire pH range using the speciation and transport modelling framework ORCHESTRA, for which mineral saturation, solution speciation and sorption processes can be calculated based on equilibrium models and thermodynamic data. The simulated equilibrium concentrations by this model agreed well with the respective measured concentrations. The main differences between the fresh and aged materials were quantified, described and predicted by the ORCHESTRA. Solubility controlling mineral phase assemblages were calculated by the model as function of pH. Cement hydrate phases such as calcium silicate hydrate, calcium aluminate hydrate (AFm and AFt) and hydrogarnet were predominating at the material pH. The concentration of carboaluminates was found to be strongly dependent on the available carbonates in the samples. As the pH was decreased these phases decomposed to more soluble species or precipitates were formed including iron- and aluminium hydroxides, wairakite and amorphous silica. In the most acid region most phases dissolved, and the major elements were approaching maximum leachability, which was determined by the amount of cement paste.

  14. Using of Glass Wastes as a Fine Aggregate in Concrete Mixture

    Directory of Open Access Journals (Sweden)

    Mohammad F. Al-Deen

    2013-04-01

    Full Text Available In this study, the waste glass (WG is considered as a fine aggregate in the concretemixture. WG is used after grinding to size according to Iraqi sand specificationsNo.45. The waste glass has been used instead of sand in different proportions whichare 0%, 33%, 66% and 100%. The effects of WG on compressive strength of theconcrete and unit weight are analysed. As results of this study, WG is determined tohave a significant effect upon the reduction of its compressive strength and there is asignificant decreasing of its unit weight. As for cost analysis, it was determined tolower the cost of concrete production. This study was an environmental one inconsideration of the fact that WG could be used in the concrete as fine aggreagateswithout the need for a high cost or rigorous energy.

  15. Internal water curing with Liapor aggregates

    DEFF Research Database (Denmark)

    Lura, Pietro

    2005-01-01

    Internal water curing is a very efficient way to counteract self-desiccation and autogenous shrinkage in high performance concrete, thereby reducing the likelihood of early-age cracking. This paper deals with early-age volume changes and moisture transport in lightweight aggregate concrete realized...... with wet lightweight aggregates. Lightweight aggregate concrete mixtures with different degree of saturation and different particle size of the lightweight aggregates were studied and compared to normal weight concrete. Autogenous deformations, selfinduced stresses in fully restrained conditions, elastic...

  16. Experimental Study on Thermal Conductivity of Self-Compacting Concrete with Recycled Aggregate.

    Science.gov (United States)

    Fenollera, María; Míguez, José Luis; Goicoechea, Itziar; Lorenzo, Jaime

    2015-07-20

    The research focuses on the use of recycled aggregate (RA), from waste pieces generated during production in precast plants for self-compacting concrete (SCC) manufactured with a double sustainable goal: recycle manufacturing waste (consumption) and improvement of the thermal properties of the manufactured product (energy efficiency). For this purpose, a mechanical study to ensure technical feasibility of the concrete obtained has been conducted, as well as a thermal analysis of recycled SCC specimens of 50 N/mm² resistance, with different RA doses (0%, 20%, 50% and 100%). The main parameters that characterize a SCC in both states, fresh (slump-flow) and hard (compressive strength), have been tested; also, a qualitative analysis of the thermal conductivity using infrared thermography (IRT) and quantitative analysis with heat flow meter at three temperatures 20 °C, 25 °C and 30 °C have been performed. The results suggest the existence of two different thermal behaviors: concretes with 0% and 20% of RA, and on the other hand concretes with 50% and 100% of RA. It has also demonstrated the validity of the IRT as sampling technique in estimating the thermal behavior of materials having reduced range of variation in parameters.

  17. Stress-Strain Relationship of Synthetic Fiber Reinforced Concrete Columns

    Directory of Open Access Journals (Sweden)

    Rosidawani

    2017-01-01

    Full Text Available Many empirical confinement models for normal and high strength concrete have been developed. Nevertheless, reported studies in the term of confinement of fiber reinforced concrete are limited. Whereas, the use of fiber reinforced concrete in structural elements has become the subject of the research and has indicated positive experiences. Since the stress-strain relationship of concrete in compression is required for analysis of structural members, the study of the stress-strain relationship for synthetic fiber reinforced concrete is substantial. The aim of the study is to examine the capabilities of the various models available in the literature to predict the actual experimental behavior of synthetic fiber reinforced high-strength concrete columns. The experimental data used are the results of the circular column specimens with the spiral spacing and the volume fraction of synthetic fiber as the test variables. The axial stress-strain curves from the tests are then compared with the various models of confinement from the literature. The performance index of each model is measured by using the coefficient of variation (COV concept of stress and strain behavior parameter. Among the confinement models, Cusson model shows the closest valid value of the coefficient of variation.

  18. The Acoustical Properties of the Polyurethane Concrete Made of Oyster Shell Waste Comparing Other Concretes as Architectural Design Components

    Science.gov (United States)

    Setyowati, Erni; Hardiman, Gagoek; Purwanto

    2018-02-01

    This research aims to determine the acoustical properties of concrete material made of polyurethane and oyster shell waste as both fine aggregate and coarse aggregate comparing to other concrete mortar. Architecture needs aesthetics materials, so the innovation in architectural material should be driven through the efforts of research on materials for building designs. The DOE methods was used by mixing cement, oyster shell, sands, and polyurethane by composition of 160 ml:40 ml:100 ml: 120 ml respectively. Refer to the results of previous research, then cement consumption is reduced up to 20% to keep the concept of green material. This study compared three different compositions of mortars, namely portland cement concrete with gravel (PCG), polyurethane concrete of oyster shell (PCO) and concrete with plastics aggregate (PCP). The methods of acoustical tests were conducted refer to the ASTM E413-04 standard. The research results showed that polyurethane concrete with oyster shell waste aggregate has absorption coefficient 0.52 and STL 63 dB and has a more beautiful appearance when it was pressed into moulding. It can be concluded that polyurethane concrete with oyster shell aggregate (PCO) is well implemented in architectural acoustics-components.

  19. The Use of Seashell by-Products in Pervious Concrete Pavers

    OpenAIRE

    Dang Hanh Nguyen; Nassim Sebaibi; Mohamed Boutouil; Lydia Leleyter; Fabienne Baraud

    2013-01-01

    Pervious concrete is a green alternative to conventional pavements with minimal fine aggregate and a high void content. Pervious concrete allows water to infiltrate through the pavement, thereby reducing the runoff and the requirement for stormwater management systems. Seashell By-Products (SBP) are produced in an important quantity in France and are considered as waste. This work investigated to use SBP in pervious concrete and produce an even more environmentally friendly product, Pervi...

  20. Evaluation of concrete recycling system efficiency for ready-mix concrete plants.

    Science.gov (United States)

    Vieira, Luiz de Brito Prado; Figueiredo, Antonio Domingues de

    2016-10-01

    The volume of waste generated annually in concrete plants is quite large and has important environmental and economic consequences. The use of fresh concrete recyclers is an interesting way for the reuse of aggregates and water in new concrete production. This paper presents a study carried out for over one year by one of the largest ready-mix concrete producers in Brazil. This study focused on the evaluation of two recyclers with distinct material separation systems, herein referred to as drum-type and rotary sieve-type equipment. They were evaluated through characterization and monitoring test programs to verify the behaviour of recovered materials (aggregates, water, and slurry). The applicability of the recovered materials (water and aggregates) was also evaluated in the laboratory and at an industrial scale. The results obtained with the two types of recyclers used were equivalent and showed no significant differences. The only exception was in terms of workability. The drum-type recycler generated fewer cases that required increased pumping pressure. The analysis concluded that the use of untreated slurry is unfeasible because of its intense negative effects on the strength and workability of concrete. The reclaimed water, pre-treated to ensure that its density is less than 1.03g/cm(3), can be used on an industrial scale without causing any harm to the concrete. The use of recovered aggregates consequently induces an increase in water demand and cement consumption to ensure the workability conditions of concrete that is proportional to the concrete strength level. Therefore, the viability of their use is restricted to concretes with characteristic strengths lower than 25MPa. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Study of the reuse of construction residues in concrete employed by blocks manufacture

    Directory of Open Access Journals (Sweden)

    R. C. C. Lintz

    Full Text Available The use of construction and demolition waste (CDR comes as an alternative for recycling, for costs reduction and for raw material. The CONAMA Resolution 307 (National Council for the Environment establishes that all cities should find an environmentally correct destination to CDR. In this research the mechanical properties of the concrete containing CDR were analyzed aiming its use in the production of concrete blocks. Here, increasing percentages of aggregates of CDR with the same granulometry an substitute the natural aggregate, and then concrete blocks were molded. Tests were then performed in order to determine the compression strength according to NBR 12118:2007, at ages of 14 days and 28 days. It was noticed that the values resulting from the compression strength test were also influenced by the increasing substitution of CDR percentages to the mixture. This research discusses the great potential of using this material in substitution to the natural aggregates used in the production of concrete based materials such as blocks.

  2. Processed bottom ash for replacing fine aggregate in making high-volume fly ash concrete

    OpenAIRE

    Antoni; Sulistio Aldi Vincent; Wahjudi Samuel; Hardjito Djwantoro; Hardjito Djwantoro

    2017-01-01

    Bottom ash is a coal plant by-product that is abundant and underutilized. There is the potential use of bottom ash as a fine aggregate replacement in concrete mixtures; however, the problems of water absorption and uniformity of quality of the material need to be overcome first. In this study, bottom ash was treated by sieve separation and pounding to smaller particle size for use as a sand substitute. The physical and chemical characteristics of bottom ash were tested after treatment includi...

  3. Evaluation of the Effects of Crushed and Expanded Waste Glass Aggregates on the Material Properties of Lightweight Concrete Using Image-Based Approaches.

    Science.gov (United States)

    Chung, Sang-Yeop; Abd Elrahman, Mohamed; Sikora, Pawel; Rucinska, Teresa; Horszczaruk, Elzbieta; Stephan, Dietmar

    2017-11-25

    Recently, the recycling of waste glass has become a worldwide issue in the reduction of waste and energy consumption. Waste glass can be utilized in construction materials, and understanding its effects on material properties is crucial in developing advanced materials. In this study, recycled crushed and expanded glasses are used as lightweight aggregates for concrete, and their relation to the material characteristics and properties is investigated using several approaches. Lightweight concrete specimens containing only crushed and expanded waste glass as fine aggregates are produced, and their pore and structural characteristics are examined using image-based methods, such as scanning electron microscopy (SEM), X-ray computed tomography (CT), and automated image analysis (RapidAir). The thermal properties of the materials are measured using both Hot Disk and ISOMET devices to enhance measurement accuracy. Mechanical properties are also evaluated, and the correlation between material characteristics and properties is evaluated. As a control group, a concrete specimen with natural fine sand is prepared, and its characteristics are compared with those of the specimens containing crushed and expanded waste glass aggregates. The obtained results support the usability of crushed and expanded waste glass aggregates as alternative lightweight aggregates.

  4. Evaluation of the Effects of Crushed and Expanded Waste Glass Aggregates on the Material Properties of Lightweight Concrete Using Image-Based Approaches

    Directory of Open Access Journals (Sweden)

    Sang-Yeop Chung

    2017-11-01

    Full Text Available Recently, the recycling of waste glass has become a worldwide issue in the reduction of waste and energy consumption. Waste glass can be utilized in construction materials, and understanding its effects on material properties is crucial in developing advanced materials. In this study, recycled crushed and expanded glasses are used as lightweight aggregates for concrete, and their relation to the material characteristics and properties is investigated using several approaches. Lightweight concrete specimens containing only crushed and expanded waste glass as fine aggregates are produced, and their pore and structural characteristics are examined using image-based methods, such as scanning electron microscopy (SEM, X-ray computed tomography (CT, and automated image analysis (RapidAir. The thermal properties of the materials are measured using both Hot Disk and ISOMET devices to enhance measurement accuracy. Mechanical properties are also evaluated, and the correlation between material characteristics and properties is evaluated. As a control group, a concrete specimen with natural fine sand is prepared, and its characteristics are compared with those of the specimens containing crushed and expanded waste glass aggregates. The obtained results support the usability of crushed and expanded waste glass aggregates as alternative lightweight aggregates.

  5. Study of the Technical Feasibility of Increasing the Amount of Recycled Concrete Waste Used in Ready-Mix Concrete Production.

    Science.gov (United States)

    Fraile-Garcia, Esteban; Ferreiro-Cabello, Javier; López-Ochoa, Luis M; López-González, Luis M

    2017-07-18

    The construction industry generates a considerable amount of waste. Faced with this undesirable situation, the ready-mix concrete sector, in particular, has invested energy and resources into reusing its own waste in its production process as it works towards the goal of more sustainable construction. This study examines the feasibility of incorporating two types of concrete waste, which currently end up in landfill, into the production process of ready-mix concrete: the waste generated during the initial production stage (ready-mix concrete waste), and waste created when demolition waste is treated to obtain artificial aggregate. The first phase of the study's methodology corroborates the suitability of the recycled aggregate through characterization tests. After this phase, the impact of incorporating different percentages of recycled coarse aggregate is evaluated by examining the performance of the produced concrete. The replacement rate varied between 15% and 50%. The results indicate that recycled aggregates are, indeed, suitable to be incorporated into ready-mix concrete production. The impact on the final product's performance is different for the two cases examined herein. Incorporating aggregates from generic concrete blocks led to a 20% decrease in the produced concrete's strength performance. On the other hand, using recycled aggregates made from the demolition waste led to a smaller decrease in the concrete's performance: about 8%. The results indicate that with adequate management and prior treatment, the waste from these plants can be re-incorporated into their production processes. If concrete waste is re-used, concrete production, in general, becomes more sustainable for two reasons: less waste ends up as landfill and the consumption of natural aggregates is also reduced.

  6. Potential assessment of Sergipe and Alagoas clays in aggregates production for use in concrete

    International Nuclear Information System (INIS)

    Oliveira, H.A.; Santos, C.P.; Oliveira, R.M.P.B.; Jesus, E. de; Macedo, Z.S.

    2017-01-01

    This study aims to characterize technologically three clays employed by ceramic industries in Sergipe state, Brazil. Its potential use for the production of calcined synthetic aggregate to substitute gravel in concrete production was evaluated. The characterization of the clays included particle size and plasticity analysis, X-ray diffraction, differential and thermogravimetric analyses, dilatometry, X-ray fluorescence, organic matter content, cation exchange capacity, specific area, and scanning electron microscopy. Ceramic bodies were uniaxially pressed under 30 MPa, into rectangular and cylindrical shapes. Ceramic bodies of individual clays and also ceramic formulations were fired and subsequently characterized to determine their water absorption, apparent density, compressive strength, and grain morphology. It was observed that, after firing at 1120 deg C, two formulations presented strength, water absorption and specific mass comparable to those of gravel used in concrete. (author)

  7. Performance Evaluation of Concrete using Marble Mining Waste

    Science.gov (United States)

    Kore, Sudarshan Dattatraya; Vyas, A. K.

    2016-12-01

    A huge amount waste (approximately 60%) is generated during mining and processing in marble industries. Such waste can be best utilized in infrastructure development works. Coarse aggregate 75% by weight was replaced by aggregate obtained from marble mining waste. The impact of marble waste as a partial replacement for conventional coarse aggregate on the properties of concrete mixes such as workability, compressive strength, permeability, abrasion, etc. was evaluated. The test results revealed that the compressive strength was comparable to that of control concrete. Other properties such as workability of concrete increased, water absorption reduced by 17%, and resistance to abrasion was marginally increased by 2% as compared to that of control concrete. Ultrasonic pulse velocity and FTIR results show improvement in quality of concrete with crushed marble waste. From the TGA analysis it was confirmed that, aggregate produced from marble waste shows better performance under elevated temperature than that of conventional aggregates.

  8. RELATIONSHIPS BETWEEN SOIL MICROBIAL BIOMASS, AGGREGATE STABILITY AND AGGREGATE ASSOCIATED-C: A MECHANISTIC APPROACH

    Directory of Open Access Journals (Sweden)

    Patrizia Guidi

    2014-01-01

    Full Text Available For the identification of C pools involved in soil aggregation, a physically-based aggregate fractionation was proposed, and  additional pretreatments were used in the measurement of the 1-2 mm aggregate stability in order to elucidate the relevance of the role of soil microorganisms with respect to the different aggregate breakdown mechanisms. The study was carried out on three clay loam Regosols, developed on calcareous shales, known history of organic cultivation.Our results showed that the soil C pool controlling the process of stabilisation of aggregates was related to the microbial community. We identified the resistance to fast wetting as the major mechanism of aggregate stability driven by microorganims. The plausible hypothesis is that organic farming promotes fungi growth, improving water repellency of soil aggregates by fungal hydrophobic substances. By contrast, we failed in the identification of C pools controlling the formation of aggregates, probably because of the disturbance of mechanical tillage which contributes to the breakdown of soil aggregates.The physically-based aggregate fractionation proposed in this study resulted useful in the  mechanistically understanding of the role of microorganisms in soil aggregation and it might be suggested for studying the impact of management on C pools, aggregates properties and their relationships in agricultural soils.

  9. Load-carrying capacity of lightly reinforced, prefabricated walls of lightweight aggregate concrete with open structure

    DEFF Research Database (Denmark)

    Goltermann, Per

    2009-01-01

    The paper presents and evaluates the results of a coordinated testing of prefabricated, lightly reinforced walls of lightweight aggregate concrete with open structure. The coordinated testing covers all wall productions in Denmark and will therefore provide a representative assessment...

  10. Concrete performance using low-degradation aggregates.

    Science.gov (United States)

    2012-06-01

    The durability of Portland cement concrete (PCC) has long been identified as a concern by transportation communities around the United States. In this study, the long-term performance of two batches of concrete incorporating either low-degradation (L...

  11. Development of Fast Fourier Transform (FFT) micro-mechanical simulations of concrete specimens characterized by micro-X-ray fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Giorla, Alain B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    Concrete in Nuclear Power Plants (NPPs) can be exposed to a wide range of degradation phenomena. In the past years, the Light Water Reactor Sustainability (LWRS) program has investigated Radiation-Induced Volumetric Expansion (RIVE) as a potential degradation mechanism for concrete biological shields [Graves et al., 2014, Rosseel et al., 2016]. RIVE causes swelling and micro-mechanical damage in concrete due to the amorphization of mineral phases contained in the aggregates under neutron irradiation [Hilsdorf et al., 1978, Rosseel et al., 2016]. For long-term operations, it is critical to assess the durability of concrete after 60 or 80 years of exposure to NPP operating conditions against this phenomenon. RIVE is dependent on the composition of the aggregates used in concrete. Quartz-bearing aggregates are more sensitive to RIVE than calcite-bearing aggregates, for example. However, the aggregate composition of a specific plant is generally not explicitly given in the concrete formulation, which makes it nearly impossible to predict the resistance of that concrete to RIVE. Additional characterization is needed to identify the radiation-sensitive mineral phases contained in the aggregates.

  12. Influence of granitic aggregates from Northeast Brazil on the alkali-aggregate reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gomes Neto, David de Paiva; Santana, Rodrigo Soares de; Barreto, Ledjane Silva, E-mail: pvgomes@uol.com.br [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Ciencias dos Materiais e Engenharia; Conceicao, Herbert; Lisboa, Vinicios Anselmo Carvalho [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil). Dept. de Geologia

    2014-08-15

    The alkali-aggregate reaction (AAR) in concrete structures is a problem that has concerned engineers and researchers for decades. This reaction occurs when silicates in the aggregates react with the alkalis, forming an expanded gel that can cause cracks in the concrete and reduce its lifespan. The aim of this study was to characterize three coarse granitic aggregates employed in concrete production in northeastern Brazil, correlating petrographic analysis with the kinetics of silica dissolution and the evolution of expansions in mortar bars, assisted by SEM/EDS, XRD, and EDX. The presence of grains showing recrystallization into individual microcrystalline quartz subgrains was associated with faster dissolution of silica and greater expansion in mortar bars. Aggregates showing substantial deformation, such as stretched grains of quartz with strong undulatory extinction, experienced slower dissolution, with reaction and expansion occurring over longer periods that could not be detected using accelerated tests with mortar bars. (author)

  13. Experimental Study on Thermal Conductivity of Self-Compacting Concrete with Recycled Aggregate

    Directory of Open Access Journals (Sweden)

    María Fenollera

    2015-07-01

    Full Text Available The research focuses on the use of recycled aggregate (RA, from waste pieces generated during production in precast plants for self-compacting concrete (SCC manufactured with a double sustainable goal: recycle manufacturing waste (consumption and improvement of the thermal properties of the manufactured product (energy efficiency. For this purpose, a mechanical study to ensure technical feasibility of the concrete obtained has been conducted, as well as a thermal analysis of recycled SCC specimens of 50 N/mm2 resistance, with different RA doses (0%, 20%, 50% and 100%. The main parameters that characterize a SCC in both states, fresh (slump-flow and hard (compressive strength, have been tested; also, a qualitative analysis of the thermal conductivity using infrared thermography (IRT and quantitative analysis with heat flow meter at three temperatures 20 °C, 25 °C and 30 °C have been performed. The results suggest the existence of two different thermal behaviors: concretes with 0% and 20% of RA, and on the other hand concretes with 50% and 100% of RA. It has also demonstrated the validity of the IRT as sampling technique in estimating the thermal behavior of materials having reduced range of variation in parameters.

  14. Experimental Study on Thermal Conductivity of Self-Compacting Concrete with Recycled Aggregate

    Science.gov (United States)

    Fenollera, María; Míguez, José Luis; Goicoechea, Itziar; Lorenzo, Jaime

    2015-01-01

    The research focuses on the use of recycled aggregate (RA), from waste pieces generated during production in precast plants for self-compacting concrete (SCC) manufactured with a double sustainable goal: recycle manufacturing waste (consumption) and improvement of the thermal properties of the manufactured product (energy efficiency). For this purpose, a mechanical study to ensure technical feasibility of the concrete obtained has been conducted, as well as a thermal analysis of recycled SCC specimens of 50 N/mm2 resistance, with different RA doses (0%, 20%, 50% and 100%). The main parameters that characterize a SCC in both states, fresh (slump-flow) and hard (compressive strength), have been tested; also, a qualitative analysis of the thermal conductivity using infrared thermography (IRT) and quantitative analysis with heat flow meter at three temperatures 20 °C, 25 °C and 30 °C have been performed. The results suggest the existence of two different thermal behaviors: concretes with 0% and 20% of RA, and on the other hand concretes with 50% and 100% of RA. It has also demonstrated the validity of the IRT as sampling technique in estimating the thermal behavior of materials having reduced range of variation in parameters. PMID:28793449

  15. Performance Evaluation of Stone Mastic Asphalt and Hot Mix Asphalt Mixtures Containing Recycled Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    Mohammad Saeed Pourtahmasb

    2014-01-01

    Full Text Available Environmental and economic considerations have encouraged civil engineers to find ways to reuse recycled materials in new constructions. The current paper presents an experimental research on the possibility of utilizing recycled concrete aggregates (RCA in stone mastic asphalt (SMA and hot mix asphalt (HMA mixtures. Three categories of RCA in various percentages were mixed with virgin granite aggregates to produce SMA and HMA specimens. The obtained results indicated that, regardless of the RCA particular sizes, the use of RCA to replace virgin aggregates increased the needed binder content in the asphalt mixtures. Moreover, it was found that even though the volumetric and mechanical properties of the asphalt mixtures are highly affected by the sizes and percentages of the RCA but, based on the demands of the project and traffic volume, utilizing specific amounts of RCA in both types of mixtures could easily satisfy the standard requirements.

  16. Characteristics of Recycled Concrete Aggregates from Precast Slab Block Buildings

    Science.gov (United States)

    Venkrbec, Václav; Nováková, Iveta; Henková, Svatava

    2017-10-01

    Precast slab block buildings (PSBB) typically and frequently occur in Central and Eastern Europe, as well as elsewhere in the world. Some of these buildings are currently used beyond their service life capacity. The utilization of recycled materials from these buildings with regard to applying the principles of sustainable construction and using recycled materials will probably be significant in the following years. Documentation from the manufacturing processes of prefabricated blocks for precast slab block buildings is not available, and also it is difficult to declare technological discipline during the construction of these buildings. Therefore, properties of recycled concrete aggregates (RCA) produced from construction and demolition waste (C&DW) of precast slab block buildings build between 1950s to 1990s are not sufficiently known. The demolition of these buildings is very rare today, but it can be assumed an increase in demolitions of these buildings in the future. The use of RCA in new concrete requires verification/testing of the geometrical and physical properties of RCA according to the EN 12 620+A1 standard. The aim of the contribution is to present a case study of the demolition of slab block building with emphasis on RCA usage. The paper presents the results of the tests according to European standards for determining selected geometrical and physical properties of the RCA. The paper describes and evaluates tests such as determination of particle size distribution - Sieve Analysis, content of fine particles, determination of density and water absorption. The results of the properties testing of RCA are compared with the properties of natural aggregate. The general boundary conditions of RCA particular tests are presented.

  17. An Investigation into the Use of Manufactured Sand as a 100% Replacement for Fine Aggregate in Concrete

    Directory of Open Access Journals (Sweden)

    Martins Pilegis

    2016-06-01

    Full Text Available Manufactured sand differs from natural sea and river dredged sand in its physical and mineralogical properties. These can be both beneficial and detrimental to the fresh and hardened properties of concrete. This paper presents the results of a laboratory study in which manufactured sand produced in an industry sized crushing plant was characterised with respect to its physical and mineralogical properties. The influence of these characteristics on concrete workability and strength, when manufactured sand completely replaced natural sand in concrete, was investigated and modelled using artificial neural networks (ANN. The results show that the manufactured sand concrete made in this study generally requires a higher water/cement (w/c ratio for workability equal to that of natural sand concrete due to the higher angularity of the manufactured sand particles. Water reducing admixtures can be used to compensate for this if the manufactured sand does not contain clay particles. At the same w/c ratio, the compressive and flexural strength of manufactured sand concrete exceeds that of natural sand concrete. ANN proved a valuable and reliable method of predicting concrete strength and workability based on the properties of the fine aggregate (FA and the concrete mix composition.

  18. An Investigation into the Use of Manufactured Sand as a 100% Replacement for Fine Aggregate in Concrete.

    Science.gov (United States)

    Pilegis, Martins; Gardner, Diane; Lark, Robert

    2016-06-02

    Manufactured sand differs from natural sea and river dredged sand in its physical and mineralogical properties. These can be both beneficial and detrimental to the fresh and hardened properties of concrete. This paper presents the results of a laboratory study in which manufactured sand produced in an industry sized crushing plant was characterised with respect to its physical and mineralogical properties. The influence of these characteristics on concrete workability and strength, when manufactured sand completely replaced natural sand in concrete, was investigated and modelled using artificial neural networks (ANN). The results show that the manufactured sand concrete made in this study generally requires a higher water/cement (w/c) ratio for workability equal to that of natural sand concrete due to the higher angularity of the manufactured sand particles. Water reducing admixtures can be used to compensate for this if the manufactured sand does not contain clay particles. At the same w/c ratio, the compressive and flexural strength of manufactured sand concrete exceeds that of natural sand concrete. ANN proved a valuable and reliable method of predicting concrete strength and workability based on the properties of the fine aggregate (FA) and the concrete mix composition.

  19. Durability of heavyweight concrete containing barite

    International Nuclear Information System (INIS)

    Binici, Hanifi

    2010-01-01

    The supplementary waste barite aggregates deposit in Osmaniye, southern Turkey, has been estimated at around 500 000 000 tons based on 2007 records. The aim of the present study is to investigate the durability of concrete incorporating waste barite as coarse and river sand (RS), granule blast furnace slag (GBFS), granule basaltic pumice (GBP) and ≤ 4 mm granule barite (B) as fine aggregates. The properties of the fresh concrete determined included the air content, slump, slump loss and setting time. They also included the compressive strength, flexural and splitting tensile strengths and Young's modulus of elasticity, resistance to abrasion and sulphate resistance of hardened concrete. Besides these, control mortars were prepared with crushed limestone aggregates. The influence of waste barite as coarse aggregates and RS, GBFS, GBP and B as fine aggregates on the durability of the concretes was evaluated. The mass attenuation coefficients were calculated at photon energies of 1 keV to 100 GeV using XCOM and the obtained results were compared with the measurements at 0.66 and 1.25 MeV. The results showed the possibility of using these waste barite aggregates in the production of heavy concretes. In several cases, some of these properties have been improved. Durability of the concrete made with these waste aggregates was improved. Thus, these materials should be preferably used as aggregates in heavyweight concrete production. (orig.)

  20. The effect of limestone aggregate porosity and saturation degree on the interfacial zone

    International Nuclear Information System (INIS)

    Nguyen, T.D.; Le Saout, G.; Devillers, P.; Garcia-Diaz, E.

    2015-01-01

    The recycling of concrete wastes concerns the nuclear industry as many nuclear facilities will have to be dismantled and the reduction and reuse of the decommissioning concrete wastes in order to minimize the total waste volume is a key issue. The recycled aggregates have the potential to replace natural resources however it is necessary to assess the effect of recycled aggregates on the final concrete. One important issue to be addressed to achieve the required mechanical properties is the water absorption of the recycled aggregates. As a first step, we have used in this study limestone aggregates with different porosities (total porosity from 2 to 20 %) and have investigated the influence of the porosity and the initial saturation degree of these aggregates on the porosity of the interfacial transition zone (ITZ) using scanning electron microscope. The equation of Feret for the strength-porosity relationship of our mortars was applied σ = K(100-p) 2 where σ is the compressive strength in MPa, p is the capillary pore volume in % and K a constant. Aggregates with lower porosity follow the same law characterized by a K value higher than the value for the more porous aggregate law. The K parameter is not dependent of the humidity degree of the aggregate: for a given aggregate, family mortars made with dry and wet aggregate follow the same law. But for porous aggregates as the meso-porosity of the ITZ for a given time of hydration is higher for mortars made with wet aggregates, the compressive strength of these mortars is less than those of mortars made with dry aggregates. Contrary to the low porous aggregate, it was not possible for porous limestone aggregates, and with a calculation based on the saturated surface dry state as reference state to obtain the same net water to cement ratio with wet and dry aggregates. This study reflects the difficulty to control the amount of efficient water in concrete when using porous aggregates and its influence on compressive

  1. Study of the Technical Feasibility of Increasing the Amount of Recycled Concrete Waste Used in Ready-Mix Concrete Production

    Science.gov (United States)

    Ferreiro-Cabello, Javier; López-González, Luis M.

    2017-01-01

    The construction industry generates a considerable amount of waste. Faced with this undesirable situation, the ready-mix concrete sector, in particular, has invested energy and resources into reusing its own waste in its production process as it works towards the goal of more sustainable construction. This study examines the feasibility of incorporating two types of concrete waste, which currently end up in landfill, into the production process of ready-mix concrete: the waste generated during the initial production stage (ready-mix concrete waste), and waste created when demolition waste is treated to obtain artificial aggregate. The first phase of the study’s methodology corroborates the suitability of the recycled aggregate through characterization tests. After this phase, the impact of incorporating different percentages of recycled coarse aggregate is evaluated by examining the performance of the produced concrete. The replacement rate varied between 15% and 50%. The results indicate that recycled aggregates are, indeed, suitable to be incorporated into ready-mix concrete production. The impact on the final product’s performance is different for the two cases examined herein. Incorporating aggregates from generic concrete blocks led to a 20% decrease in the produced concrete’s strength performance. On the other hand, using recycled aggregates made from the demolition waste led to a smaller decrease in the concrete’s performance: about 8%. The results indicate that with adequate management and prior treatment, the waste from these plants can be re-incorporated into their production processes. If concrete waste is re-used, concrete production, in general, becomes more sustainable for two reasons: less waste ends up as landfill and the consumption of natural aggregates is also reduced. PMID:28773183

  2. Investigation of Self Consolidating Concrete Containing High Volume of Supplementary Cementitious Materials and Recycled Asphalt Pavement Aggregates

    Science.gov (United States)

    Patibandla, Varun chowdary

    The use of sustainable technologies such as supplementary cementitiuous materials (SCMs), and/or recycled materials is expected to positively affect the performance of concrete mixtures. However, it is important to study and qualify such mixtures and check if the required specifications of their intended application are met before they can be implemented in practice. This study presents the results of a laboratory investigation of Self Consolidating concrete (SCC) containing sustainable technologies. A total of twelve concrete mixtures were prepared with various combinations of fly ash, slag, and recycled asphalt pavement (RAP). The mixtures were divided into three groups with constant water to cementitiuous materials ratio of 0.37, and based on the RAP content; 0, 25, and 50% of coarse aggregate replaced by RAP. All mixtures were prepared to achieve a target slump flow equal to or higher than 500 mm (24in). A control mixture for each group was prepared with 100% Portland cement whereas all other mixtures were designed to have up to 70% of portland cement replaced by a combination of supplementary cementitiuous materials (SCMs) such as class C fly ash and granulated blast furnace slag. The properties of fresh concrete investigated in this study include flowability, deformability; filling capacity, and resistance to segregation. In addition, the compressive strength at 3, 14, and 28 days, the tensile strength, and the unrestrained shrinkage up to 80 days was also investigated. As expected the inclusion of the sustainable technologies affected both fresh and hardened concrete properties. Analysis of the experimental data indicated that inclusion of RAP not only reduces the ultimate strength, but it also affected the compressive strength development rate. Moreover, several mixes satisfied compressive strength requirements for pavements and bridges; those mixes included relatively high percentages of SCMs and RAP. Based on the results obtained in this study, it is not

  3. The influence of kind of coating additive on the compressive strength of RCA-based concrete prepared by triple-mixing method

    Science.gov (United States)

    Urban, K.; Sicakova, A.

    2017-10-01

    The paper deals with the use of alternative powder additives (fly ash and fine fraction of recycled concrete) to improve the recycled concrete aggregate and this occurs directly in the concrete mixing process. Specific mixing process (triple mixing method) is applied as it is favourable for this goal. Results of compressive strength after 2 and 28 days of hardening are given. Generally, using powder additives for coating the coarse recycled concrete aggregate in the first stage of triple mixing resulted in decrease of compressive strength, comparing the cement. There is no very important difference between samples based on recycled concrete aggregate and those based on natural aggregate as far as the cement is used for coating. When using both the fly ash and recycled concrete powder, the kind of aggregate causes more significant differences in compressive strength, with the values of those based on the recycled concrete aggregate being worse.

  4. Technology for reuse of contaminated concrete constituents

    International Nuclear Information System (INIS)

    Binkhorst, I.P.; Cornelissen, H.A.W.

    1998-01-01

    During decommissioning activities of nuclear installations, large amounts of contaminated concrete will have to be processed. All this concrete has to be treated and stored as radioactive waste, which implies major economical and environmental consequences. It was shown that the contamination is mainly concentrated in the porous cement stone. By separating this cement stone from the clean dense aggregate particles, a considerable volume reduction can be reached. KEMA has developed, designed and constructed a pilot plant scale test installation for separation of aggregate from contaminated concrete. The separation is based on a thermal treatment followed by milling and sieving. The clean aggregate can be re-used in concrete, whereas the (slightly) contaminated cement stone could be upgraded to a binder for concrete used in the nuclear industry. (author)

  5. Concreting organization during Chernobylsk NPP construction

    International Nuclear Information System (INIS)

    Lysyuk, R.I.; Kareva, A.P.

    1984-01-01

    Conreting organization during the Chernobylsk NPP construction is described. Processes of extra heavy concrete production and placement, which specific mass constitutes 4t/m 3 at the age of 28 days wiath metallic aggregates and 3.3-3.5 t/m 3 at the same age without aggregates, are considered in short. Basic characteristics of this concrete are presented. At the 4th power unit labour contents for construction works were a 1.5 times lower as compared to the 3rd power unit erection. This progress was achieved by round-the-clock operation of the concrete plant with the 800 m 3 /day output and also by utilization of special equipment for mechanized concrete placement: concrete pumps, automatic concrete mixer, manipulators and concrete pipelines

  6. Cement Type Influence on Alkali-Silica Reaction in Concrete with Crushed Gravel Aggregate

    Science.gov (United States)

    Rutkauskas, A.; Nagrockienė, D.; Skripkiūnas, G.

    2017-10-01

    Alkali-silica reaction is one of the chemical reactions which have a significant influence for durability of concrete. During alkali and silica reaction, silicon located in aggregates of the concrete, reacts with high alkali content. This way in the micropores of concrete is forming hygroscopic gel, which at wet environment, expanding and slowly but strongly destroying concrete structures. The goal of this paper- to determine the influence of cement type on alkali-silica reaction of mortars with crushed gravel. In the study crushed gravel with fraction 4/16 mm was used and four types of cements tested: CEM I 42.5 R; CEM I 42.5 SR; CEM II/A-S 42.5; CEM II/A-V 52.5. This study showed that crushed gravel is low contaminated on reactive particles containing of amorphous silica dioxide. The expansion after 14 days exceed 0.054 %, by RILEM AAR-2 research methodology (testing specimen dimension 40×40×160 mm). Continuing the investigation to 56 days for all specimens occurred alkaline corrosion features: microcracking and the surface plaque of gel. The results showed that the best resistance to alkaline corrosion after 14 days was obtained with cement CEM I 42.5 SR containing ash additive, and after 56 days with cement CEM II/A-V 52.5 containing low alkali content. The highest expansion after 14 and 56 days was obtained with cement CEM I 42.5 R without active mineral additives.

  7. Influencing Factors on the Interface Microhardness of Lightweight Aggregate Concrete Consisting of Glazed Hollow Bead

    Directory of Open Access Journals (Sweden)

    Gang Ma

    2015-01-01

    Full Text Available Lightweight aggregate concrete consisting of glazed hollow bead (GHB as lightweight aggregate is studied for the influence of nanosilica (NS content, prewetting time for GHB, water-cement ratio, and curing humidity, on the interface structure between GHB and cement paste. This research analyzed the influences of various factors on the interface zone structure by measuring microhardness (HV and hydration degree of cement paste (HD nearby the interface zone (1 mm between GHB and cement paste at different periods of aging. Due to the sampling limitation, the interface zone in this test is within 1 mm away from the surface of lightweight aggregate. The HD of cement paste was determined through chemically combined water (CCW test. The results were expected to reflect the influence of various factors on the interface zone structure. Results showed that the rational control of the four factors studied could fully mobilize the water absorption and desorption properties of GHB to improve the characteristics of the interfacial transition zone.

  8. The effect of bond characteristics between steel slag fine aggregate and cement paste on mechanical properties of concrete and mortar

    International Nuclear Information System (INIS)

    Yuji, W.

    1988-01-01

    The ordinary fine aggregate in concrete has been replaced by ground and sieved steel slag fine aggregate, treated and exposed to air for three months. Compared with concrete made from natural sand, properties such as compressive strength, flexural strength, elastic modules, permeability and abrasion resistance are considerably improved. The improvement increases with a decrease in w/c ratio, an increase in curing time and an increase in the replacement weight of sand. These results are due to the fact that the steel slag contains some active minerals such as C/sub 3/S, C/sub 2/S, C/sub 4/AF, etc., and shows favorable surface physical characteristics that improve the bond between steel slag particles and cement paste. The results of XRD, SEM and EPM microhardness showed that there are heavier concentration of ions, with finer crystals and a lower degree of CH orientation at the interfacial zone between steel slag particles and cement paste. The study also found small cementitious and fibrous C-S-H crystals growing from the fine aggregate, which are linked with hydrated products form cement paste making the bond and structural characteristic more favorable with cement. The steel slag fine aggregate is an active mineral similar to cement. The bond between the aggregate and cement paste is strengthened both physically and chemically

  9. Properties of Concrete partially replaced with Coconut Shell as Coarse aggregate and Steel fibres in addition to its Concrete volume

    Science.gov (United States)

    Kalyana Chakravarthy, P. R.; Janani, R.; Ilango, T.; Dharani, K.

    2017-03-01

    Cement is a binder material with various composition of Concrete but instantly it posses low tensile strength. The study deals with mechanical properties of that optimized fiber in comparison with conventional and coconut shell concrete. The accumulation of fibers arbitrarily dispersed in the composition increases the resistance to cracking, deflection and other serviceability conditions substantially. The steel fiber in extra is one of the revision in coconut shell concrete and the outcome of steel fiber in coconut shell concrete was to investigate and compare with the conventional concrete. For the given range of steel fibe from 0.5 to 2.0%, 12 beams and 36 cylindrical specimens were cast and tested to find the mechanical properties like flexural strength, split tensile, impact resistance and the modulus of elasticity of both conventional and coconut shell concrete has been studied and the test consequences are compared with the control concrete and coconut shell concrete for M25 Grade. It is fulfilled that, the steel fibers used in this venture has shown significant development in all the properties of conventional and coconut shell concrete while compared to controlled conventional and coconut shell concrete like, Flexural strength by 6.67 % for 1.0 % of steel fiber in conventional concrete and by 5.87 % for 1.5 % of steel fiber in coconut shell concrete.

  10. Sintering of MSW fly ash for reuse as a concrete aggregate.

    Science.gov (United States)

    Mangialardi, T

    2001-10-12

    The sintering process of municipal solid waste (MSW) fly ash was investigated in order to manufacture sintered products for reuse as concrete aggregates. Four types of fly ash resulting from different Italian MSW incineration plants were tested in this study. A modification of the chemical composition of MSW fly ash--through a preliminary four-stage washing treatment of this material with water--was attempted to improve the chemical and mechanical characteristics of sintered products.The sintering treatment of untreated or washed fly ash was performed on cylindrical compact specimens (15 mm in diameter and 20mm in height) at different compact pressures, sintering temperatures and times.The sintering process of untreated MSW fly ashes proved to be ineffective for manufacturing sintered products for reuse as a construction material, because of the adverse chemical characteristics of these fly ashes in terms of sulfate, chloride, and vitrifying oxide contents.A preliminary washing treatment of MSW fly ash with water greatly improved the chemical and mechanical characteristics of sintered products and, for all the types of fly ash tested, the sintered products satisfied the Italian requirements for normal weight aggregates for use in concretes having a specified strength not greater than 12 and 15N/mm(2), when measured on cylindrical and cubic specimens, respectively.A compact pressure of 28 N/mm(2), a sintering temperature of 1140 degrees C, and a sintering time of 60 min were the best operating conditions for manufacturing sintered products of washed MSW fly ash.

  11. Determination of Coefficient of Thermal Expansion (CTE) of 20MPa Mass Concrete Using Granite Aggregate

    Science.gov (United States)

    Chee Siang, GO

    2017-07-01

    Experimental test was carried out to determine the coefficient of thermal expansion (CTE) value of 20MPa mass concrete using granite aggregate. The CTE value was established using procedure proposed by Kada et al. 2002 in determining the magnitude of early-ages CTE through laboratory test which is a rather accurate way by eliminating any possible superimposed effect of others early-age thermal deformation shrinkages such as autogenous, carbonation, plastic and drying shrinkage. This was done by submitting granite concrete block samples instrumented with ST4 vibrating wire extensometers to thermal shocks. The response of the concrete samples to this shock results in a nearly instantaneous deformation, which are measured by the sensor. These deformations, as well as the temperature signal, are used to calculate the CTE. By repeating heat cycles, the variation in the early-ages of concrete CTE over time was monitored and assessed for a period of upto 7 days. The developed CTE value facilitating the verification and validation of actual maximum permissible critical temperature differential limit (rather than arbitrarily follow published value) of cracking potential. For thick sections, internal restraint is dominant and this is governed by differentials mainly. Of the required physical properties for thermal modelling, CTE is of paramount importance that with given appropriate internal restraint factor the condition of cracking due to internal restraint is governs by equation, ΔTmax= 3.663ɛctu / αc. Thus, it can be appreciated that an increase in CTE will lower the maximum allowable differential for cracking avoidance in mass concrete while an increase of tensile strain capacity will increase the maximum allowable temperature differential.

  12. Combined use of MSWI bottom ash and fly ash as aggregate in concrete formulation: environmental and mechanical considerations.

    Science.gov (United States)

    Ginés, O; Chimenos, J M; Vizcarro, A; Formosa, J; Rosell, J R

    2009-09-30

    This paper reports the experimental results obtained after casting concrete formulated with different mix proportions of municipal solid waste incineration (MSWI) by-products, bottom ash (BA) and air pollution control fly ash (APCFA), as aggregates. Several tests were performed to determine the properties of the mixed proportions. Mechanical properties of the formulations, such as compressive strength, were also determined, and two different leaching tests were performed to study their environmental effects. Some suitable concrete formulations were obtained for the 95/5 and 90/10 BA/APCFA mix proportions. These formulations showed the highest compressive strength test results, above 15 MPa, and the lowest amount of released trace metals in reference to the leaching test. The leaching mechanisms involved in the release of trace metals for the best formulations were also studied, revealing that the washing-off process may play an important role. Given the experimental data it can be concluded that these concrete mix proportions are suitable for use as non-structural concrete.

  13. Experimental study on the performance of pervious concrete

    Science.gov (United States)

    Liu, Haojie; Liu, Rentai; Yang, Honglu; Ma, Chenyang; Zhou, Heng

    2018-02-01

    With the construction of sponge city, the pervious concrete material has been developed rapidly. A high-performance pervious concrete is developed by using cement, silica fume (SF) and superplasticizer (SP). The effects of SF, SP, aggregate size, water-cement ration and aggregate-cement ratio on the permeability coefficient, compressive strength and flexural strength are studied by controlling variables, and exploring the corrosion resistance and abrasion resistance of pervious concrete. The results show that using 0.5% SP, 5% SF and small aggregate can greatly improve the strength. There is an optimum value for water-cement ratio to make the strength and permeability coefficient maximum. Compared to ordinary pervious concrete, the corrosion resistance and abrasion resistance of this pervious concrete are very good.

  14. Utilization of cement treated recycled concrete aggregates as base or subbase layer in Egypt

    Directory of Open Access Journals (Sweden)

    Ahmed Ebrahim Abu El-Maaty Behiry

    2013-12-01

    Full Text Available Recently, environmental protection has a great concern in Egypt where recycling of increased demolition debris has become a viable option to be incorporated into roads applications. An extensive laboratory program is conducted to study the feasibility of using recycled concrete aggregate (RCA mixed with traditional limestone aggregate (LSA which is currently being used in base or subbase applications in Egypt. Moreover, the influence of mixture variables on the mechanical properties of cement treated recycled aggregate (CTRA is investigated. Models to predict the compressive and tensile strengths based on mixture parameters are established. The results show that the adding of RCA improves the mechanical properties of the mixture where the unconfined compressive strength (UCS is taken as an important quality indicator. Variables influencing the UCS such as cement content, curing time, dry density play important roles to determine the performance of CTRA.

  15. Assessment of the Characteristic Aggregates during a Decontamination of Contaminated Concrete Waste

    International Nuclear Information System (INIS)

    Min, B. Y.; Choi, W. K.; Oh, W. Z.; Jung, C. H.; Park, J. W.

    2008-01-01

    During a decommissioning of nuclear plants and facilities, large quantities of slightly contaminated concrete wastes are generated. The exposure to radiation over many years could be hazardous to human health. In Korea, the decontamination and decommissioning of the retired TRIGA MARK II and III research reactors and a uranium conversion plant at the Korea Atomic Energy Research Institute (KAERI) has been under way. Hundreds of tons of concrete wastes are expected from the D and D of these facilities. Typically, the contaminated layer is only 1∼10mm thick because cementitious materials are porous media, the penetration of radionuclides may occur up to several centimeters from the surface of a material. Contaminated concrete waste can be of two forms, either a surface or bulk contamination. Bulk contamination usually arises from a neutron activation of nuclides during the service life on a component. Surface activity can be a loose contamination arising from a deposition of nuclides from an interfacing medium, and it also can be tightly bound. Most of the dismantled concrete wastes are slightly contaminated rather than activated. This decontamination can be accomplished during the course of a separation of the concrete wastes contaminated with radioactive materials through a thermal treatment step of the radionuclide (e.g. cesium and strontium), transportation of the radionuclide to fine aggregates through a mechanical treatment step such as a crushing, milling and sieving. Produced fine powder (paste) should be stabilized for the final disposal. Melting technology has been known as the one of the most effective technologies for a stabilization and volume reduction to the paste. Therefore, a melting may be a last step in the decontamination of a contaminated paste. The aim of this study was to establish the separation conditions for an optimum decontamination for the treatment of concrete wastes contaminated with radionuclides. The separation tests had been

  16. Utilization of crushed clay brick in cellular concrete production

    Directory of Open Access Journals (Sweden)

    Ali A. Aliabdo

    2014-03-01

    Full Text Available The main objective of this research program is to study the effect of using crushed clay brick as an alternative aggregate in aerated concrete. Two series of mixtures were designed to investigate the physico-mechanical properties and micro-structural analysis of autoclave aerated concrete and foamed concrete, respectively. In each series, natural sand was replaced with crushed clay brick aggregate. In both series results showed a significant reduction in unit weight, thermal conductivity and sound attenuation coefficient while porosity has increased. Improvement on compressive strength of autoclave aerated concrete was observed at a percentage of 25% and 50% replacement, while in foamed concrete compressive strength gradually decreased by increasing crushed clay brick aggregate content. A comparatively uniform distribution of pore in case of foamed concrete with natural sand was observed by scanning electron microscope, while the pores were connected mostly and irregularly for mixes containing a percentage higher than 25% clay brick aggregate.

  17. Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products

    Science.gov (United States)

    Van den Heede, Philip; Ringoot, Niels; Beirnaert, Arno; Van Brecht, Andres; Van den Brande, Erwin; De Schutter, Geert; De Belie, Nele

    2015-01-01

    Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA) from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25) could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete’s water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction. PMID:28787809

  18. Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products

    Directory of Open Access Journals (Sweden)

    Philip Van den Heede

    2015-12-01

    Full Text Available Nowadays, more efforts towards sustainability are required from the concrete industry. Replacing traditional aggregates by recycled bottom ash (BA from municipal solid waste incineration can contribute to this goal. Until now, only partial replacement has been considered to keep the concrete workability, strength and durability under control. In this research, the feasibility of a full aggregate replacement was investigated for producing prefabricated Lego bricks. It was found that the required compressive strength class for this purpose (C20/25 could be achieved. Nevertheless, a thorough understanding of the BA properties is needed to overcome other issues. As BA is highly absorptive, the concrete’s water demand is high. This workability issue can be dealt with by subjecting the fine BA fraction to a crushing operation to eliminate the porous elements and by pre-wetting the fine and coarse BA fractions in a controlled manner. In addition, a reactive NaOH washing is needed to avoid formation of longitudinal voids and the resulting expansion due to the metallic aluminum present in the BA. Regarding the long-term behavior, heavy metal leaching and freeze-thaw exposure are not problematic, though there is susceptibility to acetic and lactic acid attack and maybe increased sensitivity to alkali-silica reaction.

  19. Petrography study on altered flint aggregate by alkali-silica reaction

    International Nuclear Information System (INIS)

    Bulteel, D.; Rafai, N.; Degrugilliers, P.; Garcia-Diaz, E.

    2004-01-01

    The aim of our study is to improve our understanding of an alkali-silica reaction (ASR) via petrography. We used a chemical concrete subsystem: flint aggregate, portlandite and KOH. The altered flint aggregate is followed by optical microscopy and scanning electron microscopy (SEM) before and after acid treatment at different intervals. After acid treatment, the observations showed an increase in aggregate porosity and revealed internal degradation of the aggregate. This degradation created amorphous zones. Before acid treatment, the analyses on polished sections by scanning electron microscopy coupled with energy dispersive spectroscopy (EDS) enabled visualization of K + and Ca 2+ penetration into the aggregate. The appearance of amorphous zones and penetration of positive ions into the aggregate are correlated with the increase in the molar fraction of silanol sites. This degradation is specific to the alkali-silica reaction

  20. Field site leaching from recycled concrete aggregates applied as sub-base material in road construction.

    Science.gov (United States)

    Engelsen, Christian J; Wibetoe, Grethe; van der Sloot, Hans A; Lund, Walter; Petkovic, Gordana

    2012-06-15

    The release of major and trace elements from recycled concrete aggregates used in an asphalt covered road sub-base has been monitored for more than 4 years. A similar test field without an asphalt cover, directly exposed to air and rain, and an asphalt covered reference field with natural aggregates in the sub-base were also included in the study. It was found that the pH of the infiltration water from the road sub-base with asphalt covered concrete aggregates decreased from 12.6 to below pH 10 after 2.5 years of exposure, whereas this pH was reached within only one year for the uncovered field. Vertical temperature profiles established for the sub-base, could explain the measured infiltration during parts of the winter season. When the release of major and trace elements as function of field pH was compared with pH dependent release data measured in the laboratory, some similar pH trends were found. The field concentrations of Cd, Ni, Pb and Zn were found to be low throughout the monitoring period. During two of the winter seasons, a concentration increase of Cr and Mo was observed, possibly due to the use of de-icing salt. The concentrations of the trace constituents did not exceed Norwegian acceptance criteria for ground water and surface water Class II. Copyright © 2012 Elsevier B.V. All rights reserved.

  1. Investigation of the impact of nanotechnology on the freeze-thaw durability of concrete containing d-cracking aggregates.

    Science.gov (United States)

    2015-05-01

    Freezing and thawing damage is the most common cause of distress in Kansas pavements. Many : locally available aggregates in Kansas do not meet current standards for use in concrete pavements because : of poor freeze-thaw durability. The use of nanot...

  2. Report on reuse of concrete and masonry in foreign countries; Concrete no recycle ni kansuru kaigai no doko

    Energy Technology Data Exchange (ETDEWEB)

    Yamato, T. [Fukuoka University, Fukuoka (Japan). Faculty of Engineering

    1997-07-01

    Referring to the report by RILEM in 1976, this paper introduces the status and guidelines on recycling concrete in foreign countries. In Flanders, Belgium, a sub-committee was established in 1990 under the auspices of Environment Agency and the Ministry of Construction. Researches and investigations have been carried out to prepare flexible guidelines so that reclaimed aggregates may be used in public constructions. The Belgian Road Research Center, the Belgian Building Research Institute and its subsidiaries are supporting several investigation and research projects. In England, about 10% of aggregates is estimated to have been made of wastes and recycled materials. The seventh revised edition of the expressway construction specifications in the concrete aggregate standard BS882 has approved for use as an aggregate for pavement concrete if quality of crushed concrete meets the quality and grain size standard of BS882. Additionally, this paper shows a list of specifications and standards for reclaimed aggregates made in the U.S.A., France, Germany and other countries. 18 refs., 3 tabs.

  3. EXPERIMENTAL INVESTIGATION ON RICH MINERAL SILICA AND COCONUT SHELL IN CONCRETE

    OpenAIRE

    C. V. Saranya; V. Anusuya; T. Sreeshma Baburaj

    2017-01-01

    Concrete plays a vital role in the design and construction of the nation’s infrastructure. Almost three quarters of the volume of concrete is composed of aggregates. The current studies involved in the replacement of fine aggregate with Ecosand. In this study an attempt is made to use Ecosand which is a commercial by-product of cement manufacturing process introduced by ACC Cements, as fine aggregate replacement and crushed coconut shell as coarse aggregate. M20 grade of concrete is used. Dif...

  4. Processed bottom ash for replacing fine aggregate in making high-volume fly ash concrete

    Directory of Open Access Journals (Sweden)

    Antoni

    2017-01-01

    Full Text Available Bottom ash is a coal plant by-product that is abundant and underutilized. There is the potential use of bottom ash as a fine aggregate replacement in concrete mixtures; however, the problems of water absorption and uniformity of quality of the material need to be overcome first. In this study, bottom ash was treated by sieve separation and pounding to smaller particle size for use as a sand substitute. The physical and chemical characteristics of bottom ash were tested after treatment including water absorption, sieve analysis, and fineness modulus. Highvolume fly ash (HVFA mortar specimens were made and the compressive strength and flowability test using bottom ash after treatment are compared with that of the sand specimen. Low water to cementitious ratio was used to ensure higher strength from the cementitious paste and superplasticizer demand was determined for each treatment. The result showed that bottom ash can be used as fine aggregate replacement material. Sieve separation of the bottom ash could produce 75% of the compressive strength compared with the control sand specimen, whereas pounded bottom ash could have up to 96% of the compressive strength of the control specimen. A 28-day compressive strength of 45 MPa was achievable with 100% replacement of fine aggregate with bottom ash.

  5. Acoustic properties of porous concrete made from arlite and vermiculite lightweight aggregates

    Directory of Open Access Journals (Sweden)

    Carbajo, J.

    2015-12-01

    Full Text Available The use of sustainable materials is becoming a common practice for noise abatement in building and civil engineering industries. In this context, many applications have been found for porous concrete made from lightweight aggregates. This work investigates the acoustic properties of porous concrete made from arlite and vermiculite lightweight aggregates. These natural resources can still be regarded as sustainable since they can be recycled and do not generate environmentally hazardous waste. The experimental basis used consists of different type specimens whose acoustic performance is assessed in an impedance tube. Additionally, a simple theoretical model for granular porous media, based on parameters measurable with basic experimental procedures, is adopted to predict the acoustic properties of the prepared mixes. The theoretical predictions compare well with the absorption measurements. Preliminary results show the good absorption capability of these materials, making them a promising alternative to traditional porous concrete solutions.El uso de materiales sostenibles se está convirtiendo en una práctica común para la reducción de ruido en las industrias de la edificación e ingeniería civil. Este trabajo investiga las propiedades acústicas de hormigón poroso fabricado a partir de áridos ligeros de arlita y vermiculita. Estos recursos naturales todavía pueden considerarse sostenibles ya que pueden ser reciclados y no generan residuos peligrosos para el medio ambiente. La base experimental utilizada se compone de especímenes de diferente tipo cuyas prestaciones acústicas se evalúan en un tubo de impedancia. Adicionalmente, se ha adoptado un modelo teórico simple para medios porosos granulares, basado en parámetros medibles con procedimientos experimentales básicos, con objeto de predecir las propiedades acústicas de las mezclas preparadas. Las predicciones teóricas muestran una buena concordancia con las medidas de absorci

  6. Lightweight concrete masonry units based on processed granulate of corn cob as aggregate

    Directory of Open Access Journals (Sweden)

    Faustino, J.

    2015-06-01

    Full Text Available A research work was performed in order to assess the potential application of processed granulate of corn cob (PCC as an alternative lightweight aggregate for the manufacturing process of lightweight concrete masonry units (CMU. Therefore, CMU-PCC were prepared in a factory using a typical lightweight concrete mixture for non-structural purposes. Additionally, lightweight concrete masonry units based on a currently applied lightweight aggregate such as expanded clay (CMU-EC were also manufactured. An experimental work allowed achieving a set of results that suggest that the proposed building product presents interesting material properties within the masonry wall context. Therefore, this unit is promising for both interior and exterior applications. This conclusion is even more relevant considering that corn cob is an agricultural waste product.En este trabajo de investigación se evaluó la posible aplicación de granulado procesado de la mazorca de maiz como un árido ligero alternativo en el proceso de fabricación de unidades de mampostería de hormigón ligero. Con esta finalidad, se prepararon en una fábrica diversas unidades de mampostería no estructural con granulado procesado de la mazorca de maiz. Además, se fabricaran unidades de mampostería estándar de peso ligero basado en agregados de arcilla expandida. Este trabajo experimental permitió lograr un conjunto de resultados que sugieren que el producto de construcción propuesto presenta interesantes propiedades materiales en el contexto de la pared de mampostería. Por lo tanto, esta solución es prometedora tanto para aplicaciones interiores y exteriores. Esta conclusión es aún más relevante teniendo en cuenta que la mazorca de maíz es un producto de desecho agrícola.

  7. High flow concrete 2; Koryudo konkurito 2

    Energy Technology Data Exchange (ETDEWEB)

    Naruse, Hiroyasu [Mitsubishi Materials Corp., Tokyo (Japan)

    1998-09-10

    Hashimoto et al. compared U-type repletion test that evaluation method of the consistency in design of mix of high workable concrete was proposed as a repletion test with the box test, and it was examined, and it had clarified the difference between the behavior in the test by the analysis of the shearing strain speed by the visualization as the technique, and the important proposal was done, when the evaluation method would be divided in future. Anchors showed that it analyzed it in order to quantitatively evaluate separating resistance-ness of the coarse aggregate, with model and proposes the analysis method on separating resistance-ness of high workable concrete according to the original model, and that the correlation is high. In the future, further examination was carried out on aggregate shapes and lees aggregate amount, etc. and intended to propose the technique which could be analyzed more high-precise. Branch pines examined the effect of the fineness modulus in addition to factors such as real width rate and particle size of a fine aggregate in the technique in which researchers have proposed the setting of class aggregate amount in the top in search of the optimum value. It can be expected that it is future effectively utilized, because it is a proposed equation which sufficiently added characteristics of the Tsumugi aggregate. Temple areas found and proposed that viscosity and of the optimum mortar minute in design of mix in high workable concrete for the dam for the downward flow hour differed from the case in which the 20 mm aggregate was used on the design of mix technique in using the 40 mm aggregate. It is the research which considered the application of high workable concrete to the concrete for the dam, and it seems to be very much useful to future popularization. (translated by NEDO)

  8. Characterization of concrete properties from dielectric properties using ground penetrating radar

    International Nuclear Information System (INIS)

    Lai, W.L.; Kou, S.C.; Tsang, W.F.; Poon, C.S.

    2009-01-01

    This paper presents the experimental results of a study of the relationships between light-weight (LWAC) and normal aggregate concrete (NAC) properties, as well as radar wave properties that are derived by using ground penetrating radar (GPR). The former (LWAC) refers to compressive strength, apparent porosity and saturated density, while the latter (NAC) refers to real part of dielectric permittivity (ε' or real permittivity) and wave energy level (E). Throughout the test period of the newly cast concrete cured for 90 days, the above mentioned material properties gradually changed which can be attributed to the effects of cement hydration, different types of aggregates and initial water to binder ratios. A number of plots describing various properties of concrete such as dielectric, strength and porosity perspectives were established. From these plots, we compare the characteristics of how much and how fast free water was turned to absorbed water in LWAC and NAC. The underlying mechanisms and a mechanistic model are then developed.

  9. The ITZ in concrete with natural and recycled aggregates : Study of microstructures based on image and SEM analysis

    NARCIS (Netherlands)

    Bonifazi, G.; Capobianco, G.; Serranti, S.; Eggimann, M.; Wagner, E.; Di Maio, F.; Lotfi, S.

    2015-01-01

    Aim of this work was to investigate the microstructure of the Interfacial Transition Zone (ITZ) between cement paste and aggregate in concrete utilizing Scanning Electron Microscope (SEM) in order to identify possible effects on the ITZ related to different recipes and production parameters. SEM is

  10. Previous concrete as one of the technology to overcome the puddle

    Science.gov (United States)

    Agung Putra Handana, M.; Karolina, Rahmi; Syahputra, Eko; Zulfikar

    2018-03-01

    Some construction waste has been utilized as a material in certain concrete compositions for engineering building materials. One is a concrete that has been removed after testing at a laboratory called recycle concrete. Disposed concrete, crushed and filtered with filter number 50; 37.5; 19; 9.5; and 4.75 mm are subsequently converted into rough aggregate materials in the manufacture of pervious concrete to be tested for compressive strength and infiltration velocity to water. Pervious concrete test specimens in the form of cylinders with dimensions (15 x 30) cm and plate-shaped with dimension (100 x 100 x 10) cm with the quality plan Fc ' = 15 MPa at age 28 days. The research methodology consisted of testing of wear, test object preparation, periodic maintenance, visual inspection, compressive strength testing, and infiltration rate of specimens against water (based on ASTM C1701). Treatment of specimens by spraying periodically before the test time. From the results of the Los Angeles wear test, it appears that recycled aggregate has an average wear rate of 20.88% (based on SNI 03-2417-1991) on the Los Angeles test) and the visual test on the specimen is appropriate (based on SNI 03 -0691-1996 on paving block) as the basis for testing the specimens. The largest compressive strength was found in pervious concrete with 9.5 mm graded aggregates of 5.89 MPa, while the smallest compressive strength of 50 mm gradation was 2.15 MPa and had a compressive strength of 28% of pervious concrete compressive strength on generally (based on SNI 03-6805-2002). The fastest infiltration speed occurs in 50 mm pervious gradient concrete at 4.52 inc / hr and is late in 9.5 mm grading of 2.068 inc / hr or an inflation rate inflation rate of 54.25% for gradation of 9.5 mm to 50 mm gradation, So that in accordance with the purpose of pervious concrete use, concrete that can drain water to the bottom layer

  11. The Improvement of Thermal Insulating Concrete Panel

    Directory of Open Access Journals (Sweden)

    Mohammed Ali Nasser Ali

    2018-05-01

    Full Text Available The Iraqi houses flattening the roof by a concrete panel, and because of the panels on the top directly exposed to the solar radiation become unbearably hot and cold during the summer and winter. The traditional concrete panel components are cement, sand, and aggregate, which have a poor thermal property. The usage of materials with low thermal conductivity with no negative reflects on its mechanical properties gives good improvements to the thermal properties of the concrete panel. The practical part of this work was built on a multi-stage mixing plan. In the first stage the mixing ratio based on the ratios of the sand to cement. The second stage mixing ratios based on replacing the coarse aggregate quantities with the Alabaster aggregates, and the third stage the mixing ratios based on the replacement of wood ash instead of the sand. While the fourth stage mixing ratios based on decreasing the thermal conductivity and increasing mechanical properties by adding a multilayer of a plastic net. The result shows that using a concrete panel with components (cement, sand, coarse aggregate, wood ash, and Alabaster aggregates with a mass ratio of (1:1:2:1:1 and 3-plastic layers, gives the best improvement of the thermal properties. Where, the thermal conductivity is reduced by 42% and the specific heat increased by 41.2% as compared to the traditional concrete panel mixing ratio, with mechanical properties are agreed with the Iraqi standards.

  12. Re-utilization of concrete from decommissioned nuclear facilities by re-clinkering

    International Nuclear Information System (INIS)

    Costes, J.R.

    1998-01-01

    Usually concrete is reused as aggregates. To maximize reusing by producing a new concrete, separation of its fundamental components (aggregates, sand, cement) is required. But can already hydrated cement be re-clinkered and become new good cement again? This paper shows how specimen of pure cement paste of ordinary Portland cement was hydrated then crushed and reclinkerised. Chemical and, X ray diffraction analysis, electronic microscope coupled with X fluorescence observations, demonstrate that very few differences occurs in the cement paste before and after re-clinkering; mechanical properties of the reactivated powder are very satisfactory, even exceeding the strength of the original pure cement paste. As this process involves heating up to 1450 deg C, some of the contamination (caesium, ruthenium) may also be eliminated by volatilization and recovery on filters. This process could be very promising to complete recycle large quantities of low level contaminated concrete inside the nuclear industry as alternative to storage in specific and expensive dump, as it is now the case for steel materials. (authors)

  13. The use of waste materials for concrete production in construction applications

    Science.gov (United States)

    Teara, Ashraf; Shu Ing, Doh; Tam, Vivian WY

    2018-04-01

    To sustain the environment, it is crucial to find solutions to deal with waste, pollution, depletion and degradation resources. In construction, large amounts of concrete from buildings’ demolitions made up 30-40 % of total wastes. Expensive dumping cost, landfill taxes and limited disposal sites give chance to develop recycled concrete. Recycled aggregates were used for reconstructing damaged infrastructures and roads after World War II. However, recycled concrete consists fly ash, slag and recycled aggregate, is not widely used because of its poor quality compared with ordinary concrete. This research investigates the possibility of using recycled concrete in construction applications as normal concrete. Methods include varying proportion of replacing natural aggregate by recycled aggregate, and the substitute of cement by associated slag cement with fly ash. The study reveals that slag and fly ash are effective supplementary elements in improving the properties of the concrete with cement. But, without cement, these two elements do not play an important role in improving the properties. Also, slag is more useful than fly ash if its amount does not go higher than 50%. Moreover, recycled aggregate contributes positively to the concrete mixture, in terms of compression strength. Finally, concrete strength increases when the amount of the RA augments, related to either the high quality of RA or the method of mixing, or both.

  14. Laboratory Investigation on the Effects of Natural Fine Aggregates and Recycled Waste Tire Rubber in Pervious Concrete to Develop More Sustainable Pavement Materials

    Science.gov (United States)

    Bonicelli, Alessandra; Fuentes, Luis G.; Khalil Dawd Bermejo, Ibrahim

    2017-10-01

    Pervious concrete pavement is a recognized sustainable solution for urban roads. To enhance mechanical properties of pervious concrete material, in order to allow wider use of this technology, a lot of studies are going on all over the world. The use of a little percentage of fine aggregates is proven to increase the material resistance without an excessive reduction of permeability. This study aimed to evaluate the effect of replacing the fine virgin aggregates with r cycled tire rubber. 14 different mixes were analysed in terms of indirect tensile strength resistance, void content and density. Two different dimensions of crumb rubber were studied, as well as two different dosages, which were applied to different no-fine control mixes. All results were compared with the same control mixes containing natural fine aggregate. The mixes had a fixed granulometric curve but varied in water/cement ratio; this in order to evaluate the effect of recycled rubber depending to w/c ratio of the mix. An image analysis was also conducted to verify the rubber distribution in the mixture and the cracking surfaces. The experimental analysis showed that a correct proportioning of fine sand significantly increased the strength of the material. Moreover, the use of recycled waste tire rubber, gave interesting improvements respect to the no-fine control mixes, even though the developed resistance was lower respect to mixes containing mineral sand. This result was expected because of the cementing property of mineral sand. Although, the important result was that it was possible to use waste tire rubber in pervious concrete, with an appropriate dosage and granular dimension, for increasing the performance of traditional mix design, in order to achieve pavement materials more and more sustainable.

  15. Three-dimensional shape analysis of coarse aggregates: New techniques for and preliminary results on several different coarse aggregates and reference rocks

    International Nuclear Information System (INIS)

    Erdogan, S.T.; Quiroga, P.N.; Fowler, D.W.; Saleh, H.A.; Livingston, R.A.; Garboczi, E.J.; Ketcham, P.M.; Hagedorn, J.G.; Satterfield, S.G.

    2006-01-01

    The shape of aggregates used in concrete is an important parameter that helps determine many concrete properties, especially the rheology of fresh concrete and early-age mechanical properties. This paper discusses the sample preparation and image analysis techniques necessary for obtaining an aggregate particle image in 3-D, using X-ray computed tomography, which is then suitable for spherical harmonic analysis. The shapes of three reference rocks are analyzed for uncertainty determination via direct comparison to the geometry of their reconstructed images. A Virtual Reality Modeling Language technique is demonstrated that can give quick and accurate 3-D views of aggregates. Shape data on several different kinds of coarse aggregates are compared and used to illustrate potential mathematical shape analyses made possible by the spherical harmonic information

  16. Comparison of fine particle colemanite and boron frit in concrete for time-strength relationship

    International Nuclear Information System (INIS)

    Volkman, D.E.; Bussolini, P.L.

    1992-01-01

    This paper reports that the element boron, when added to concrete, has proved effective in shielding neutron particles by absorbing the neutron and emitting a low-energy gamma ray. The various boron additives used with concrete can severely retard the set time and strength gain. An advantage to using small particle size boron is that the smaller grain size provides better boron disbursement within the concrete matrix to absorb neutrons. However, boron additives of powder consistency are usually not used due to the greater potential of forming chemical solutions that act as a retarder in the concrete. Research has shown that the amount of boron additives in concrete can be reduced significantly if fine grain particles can be successfully incorporated into the concrete matrix. The purpose of this study is to compare strength gain characteristics of concrete mixes containing various quantities of fine grain boron additive. The boron additive colemanite, a natural mineral, is compared with two brands of manufactured aggregate, boron frit. Concrete test cylinders are molded for testing the compressive strength of the mix after 4, 7, 28, and 56 days. Tested are five different quantities of colemanite as well as five comparable amounts of boron frit for each brand of the material. The test values are compared with a control concrete specimen containing no boron additive. Results of this study can be used to optimize the cost and effectiveness of boron additives in radiation shielding concrete

  17. A comparative study of recycled aggregates from concrete and mixed debris as material for unbound road sub-base

    Directory of Open Access Journals (Sweden)

    Jiménez, J. R.

    2011-06-01

    Full Text Available Seven different types of recycled aggregates from construction and demolition waste (CDW have been evaluated as granular materials for unbound road sub-bases construction. The results showed that recycled concrete aggregates complied with all specifications for using in the construction of unbound structural layers (sub-base for T3 and T4 traffic categories according to the Spanish General Technical Specification for Road Construction (PG-3. Some mixed recycled aggregates fell short of some specifications due to a high content of sulphur compounds and poor fragmentation resistance. Sieving off the fine fraction prior to crushing the mixed CDW reduce the total sulphur content and improve the quality of the mixed recycled aggregates, by contrast, pre-sieving concrete CDW had no effect on the quality of the resulting aggregates. The results were compared with a crushed limestone as natural aggregate.

    Siete áridos reciclados de residuos de construcción y demolición (RCD se han evaluado como zahorras para la construcción de sub-bases de carreteras. Los resultados muestran que los áridos reciclados de hormigón cumplen todas las especificaciones del Pliego de Prescripciones Técnicas Generales para Obras de Carreteras de España (PG-3 para su uso en capas estructurales (sub-base de las categorías de tráfico T3 y T4. Algunos áridos reciclados mixtos no cumplen por escaso margen algunas de las especificaciones, debido a un alto contenido de compuestos de azufre y a una menor resistencia a la fragmentación. El precribado de la fracción fina antes de la trituración de los RCD mixtos reduce el contenido de azufre total y mejora la calidad, por el contrario, el precribado de los RCD de hormigón no tiene ningún efecto sobre la calidad de los áridos reciclados. Los resultados se compararon con una zahorra artificial caliza como árido natural.

  18. Waste tyre rubberized concrete: properties at fresh and hardened state.

    Science.gov (United States)

    Aiello, M A; Leuzzi, F

    2010-01-01

    The main objective of this paper is to investigate the properties of various concrete mixtures at fresh and hardened state, obtained by a partial substitution of coarse and fine aggregate with different volume percentages of waste tyres rubber particles, having the same dimensions of the replaced aggregate. Workability, unit weight, compressive and flexural strength and post-cracking behaviour were evaluated and a comparison of the results for the different rubcrete mixtures were proposed in order to define the better mix proportions in terms of mechanical properties of the rubberized concrete. Results showed in this paper were also compared to data reported in literature. Moreover, a preliminary geometrical, physical and mechanical characterization on scrap tyre rubber shreds was made. The rubberized concrete mixtures showed lower unit weight compared to plain concrete and good workability. The results of compressive and flexural tests indicated a larger reduction of mechanical properties of rubcrete when replacing coarse aggregate rather than fine aggregate. On the other hand, the post-cracking behaviour of rubberized concrete was positively affected by the substitution of coarse aggregate with rubber shreds, showing a good energy absorption and ductility indexes in the range observed for fibrous concrete, as suggested by standard (ASTM C1018-97, 1997). 2010 Elsevier Ltd. All rights reserved.

  19. PZT-Based Detection of Compactness of Concrete in Concrete Filled Steel Tube Using Time Reversal Method

    Directory of Open Access Journals (Sweden)

    Shi Yan

    2014-01-01

    Full Text Available A smart aggregate-based approach is proposed for the concrete compactness detection of concrete filled steel tube (CFST columns. The piezoceramic-based smart aggregates (SAs were embedded in the predetermined locations prior to the casting of concrete columns to establish a wave-based smart sensing system for the concrete compactness detection purpose. To evaluate the efficiency of the developed approach, six specimens of the CFST columns with the rectangular cross-section were produced by placing some artificial defects during casting of concrete for simulating various uncompacted voids such as cavities, cracks, and debond. During the test, the time reversal technology was applied to rebuild the received signals and launch the reversed signals again by SAs, to overcome the issue of the lack of the prototype. Based on the proposed nonprototype, two indices of time reversibility (TR and symmetry (SYM were applied to relatively evaluate the level of concrete compactness in the range of the two SAs. The experimental results show that the developed method can effectively detect the compactness of concrete in CFST columns.

  20. Durability and acoustics of concrete with slag of cupola furnace as fine aggregate replacement

    Directory of Open Access Journals (Sweden)

    Ricardo Alfredo Cruz Hernández

    2015-01-01

    Full Text Available In this paper, it was evaluated the performance of concrete with crushed slag of cupola furnace (SCF as sand replacement in percentages of 0 %, 10 %, 15 % and 20 %, subjected to accelerated chemical attacks of carbonation, sulfation and alkali-aggregate reaction (AAR. The sound absorption characteristics of the material were determined through the sound absorption coefficient (α, and the noise reduction coefficient (NRC. Carbonation was evaluated through a closed camera with the 70 % concentration of carbon dioxide and conditions of relative humidity between 50 % and 70 %. The results indicated that the penetration depth of CO2 is lower when greater the percentage of substitution is. To accelerate the attack by sulfates, specimens were immersed in aqueous solution of sodium sulfate anhydrous (Na2SO4 1N with cycles of wetting and drying. It determined that the impairment presented in concrete paste is directly proportional to the percentage of sand replacement. The acceleration of the AAR in the concrete was carried out by immersing specimens in an aqueous solution of sodium hydroxide (NaOH for 16 days. The test concluded that the inclusion of SCF is not favorable for AAR. The measurement of sound absorption coefficient was taken by the method of impedance tube, relating minimum and maximum values of stationary wave amplitude. The results showed that SCF with higher sand replacement are favorable for the noise absorption in buildings.

  1. Investigation of statistical relationship between dynamic modulus and thermal strength of asphalt concrete

    International Nuclear Information System (INIS)

    Qadir, A.; Gular, M.

    2011-01-01

    Dynamic modulus is a performance indicator for asphalt concrete and is used to qualify asphalt mixtures based on stress-strain characteristics under repeated loading. Moreover, the low temperature cracking of asphalt concrete mixes are measured in terms of fracture strength and fracture temperature. Dynamic modulus test was selected as one of the simple performance tests in the AASHTO 2002 guidelines to rate mixtures according to permanent deformation performance. However, AASHTO 2002 guidelines is silent in relating dynamic modulus values to low temperature cracking, probably because of weak correlations reported between these two properties. The present study investigates the relation between these two properties under the influence of aggregate type and mix gradation. Mixtures were prepared with two types of aggregate and gradations, while maintaining the binder type and air voids constant. The mixtures were later tested for dynamic modulus and fracture strength using thermal stress restrained specimen test (TSRST). Results indicate that there exists a fair correlation between the thermal fracture strength and stiffness at a selected test temperature and frequency level. These correlations are highly dependent upon the type of aggregate and mix gradation. (author)

  2. High performance of treated and washed MSWI bottom ash granulates as natural aggregate replacement within earth-moist concrete.

    Science.gov (United States)

    Keulen, A; van Zomeren, A; Harpe, P; Aarnink, W; Simons, H A E; Brouwers, H J H

    2016-03-01

    Municipal solid waste incineration bottom ash was treated with specially designed dry and wet treatment processes, obtaining high quality bottom ash granulate fractions (BGF) suitable for up to 100% replacement of natural gravel in concrete. The wet treatment (using only water for separating and washing) significantly lowers the leaching of e.g. chloride and sulfate, heavy metals (antimony, molybdenum and copper) and dissolved organic carbon (DOC). Two potential bottom ash granulate fractions, both in compliance with the standard EN 12620 (aggregates for concrete), were added into earth-moist concrete mixtures. The fresh and hardened concrete physical performances (e.g. workability, strength and freeze-thaw) of high strength concrete mixtures were maintained or improved compared with the reference mixtures, even after replacing up to 100% of the initial natural gravel. Final element leaching of monolithic and crushed granular state BGF containing concretes, showed no differences with the gravel references. Leaching of all mixtures did not exceed the limit values set by the Dutch Soil Quality Degree. In addition, multiple-life-phase emission (pH static test) for the critical elements of input bottom ash, bottom ash granulate (BGF) and crushed BGF containing concrete were assessed. Simulation pH lowering or potential carbonation processes indicated that metal (antimony, barium, chrome and copper) and sulfate element leaching behavior are mainly pH dominated and controlled, although differ in mechanism and related mineral abundance. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Concrete and criticality

    International Nuclear Information System (INIS)

    Carter, R.D.

    1978-01-01

    Concrete is a widely used structural material which occurs frequently in systems requiring criticality analyses. Ordinarily, we give little thought to what its actual composition is (as compared to reference compositions), yet in criticality safety, differences in composition can cause large changes in k-effective and it may not be easy to predict in which direction the change will occur. Concrete composition is quite variable with differences in the aggregate used in the concrete in various parts of the country providing relative large differences in k-effective. The water content of concrete can also strongly affect the reactivity of a system in which it acts as a reflector or is interspersed between fissile units. Because concrete is so common and is often (but not always) a better reflector than water, one must know the concrete compositions or be prepared to use a ''worst case'' composition. It may be a problem, however, to determine just what is the worst case. At the Hanford Plant, the aggregate normally used is basalt, which gives a composition very low in carbon as opposed to those areas (e.g., Oak Ridge) where the use of limestone aggregate will result in concrete with a high carbon content. The data presented show some of the effects found in situations using ''Hanford'' concrete, but similar effects might be found with other compositions. In some cases, the use of concrete may be incidental to the effects shown. While the numbers shown are those for actual systems, the primary intent is to alert the reader that these effects can occur. In applying this information, the analyst should use material specific to the systems being analyzed

  4. The influence of coarse aggregate size and volume on the fracture behavior and brittleness of self-compacting concrete

    International Nuclear Information System (INIS)

    Beygi, Morteza H.A.; Kazemi, Mohammad Taghi; Nikbin, Iman M.; Vaseghi Amiri, Javad; Rabbanifar, Saeed; Rahmani, Ebrahim

    2014-01-01

    This paper presents the results of an experimental investigation on fracture characteristics and brittleness of self-compacting concrete (SCC), involving the tests of 185 three point bending beams with different coarse aggregate size and content. Generally, the parameters were analyzed by the work of fracture method (WFM) and the size effect method (SEM). The results showed that with increase of size and content of coarse aggregate, (a) the fracture energy increases which is due to the change in fractal dimensions, (b) behavior of SCC beams approaches strength criterion, (c) characteristic length, which is deemed as an index of brittleness, increases linearly. It was found with decrease of w/c ratio that fracture energy increases which may be explained by the improvement in structure of aggregate-paste transition zone. Also, the results showed that there is a correlation between the fracture energy measured by WFM (G F ) and the value measured through SEM (G f ) (G F = 3.11G f )

  5. The influence of coarse aggregate size and volume on the fracture behavior and brittleness of self-compacting concrete

    Energy Technology Data Exchange (ETDEWEB)

    Beygi, Morteza H.A., E-mail: M.beygi@nit.ac.ir [Department of Civil Engineering, Babol University of Technology (Iran, Islamic Republic of); Kazemi, Mohammad Taghi, E-mail: Kazemi@sharif.edu [Department of Civil Engineering, Sharif University of Technology, P.O. Box 11155-9313 (Iran, Islamic Republic of); Nikbin, Iman M., E-mail: nikbin@iaurasht.ac.ir [Faculty of Civil Engineering, Islamic Azad University, Rasht Branch, Rasht (Iran, Islamic Republic of); Vaseghi Amiri, Javad, E-mail: Vaseghi@nit.ac.ir [Department of Civil Engineering, Babol University of Technology (Iran, Islamic Republic of); Rabbanifar, Saeed, E-mail: Saeed.rabbanifar@yahoo.com [Department of Civil Engineering, Babol University of Technology (Iran, Islamic Republic of); Rahmani, Ebrahim, E-mail: Ebrahim.rahmani84@gmail.com [Department of Civil Engineering, Babol University of Technology (Iran, Islamic Republic of)

    2014-12-15

    This paper presents the results of an experimental investigation on fracture characteristics and brittleness of self-compacting concrete (SCC), involving the tests of 185 three point bending beams with different coarse aggregate size and content. Generally, the parameters were analyzed by the work of fracture method (WFM) and the size effect method (SEM). The results showed that with increase of size and content of coarse aggregate, (a) the fracture energy increases which is due to the change in fractal dimensions, (b) behavior of SCC beams approaches strength criterion, (c) characteristic length, which is deemed as an index of brittleness, increases linearly. It was found with decrease of w/c ratio that fracture energy increases which may be explained by the improvement in structure of aggregate-paste transition zone. Also, the results showed that there is a correlation between the fracture energy measured by WFM (G{sub F}) and the value measured through SEM (G{sub f}) (G{sub F} = 3.11G{sub f})

  6. Concrete alkali-silica reaction and nuclear radiation damage

    International Nuclear Information System (INIS)

    Ichikawa, Tsuneki

    2008-01-01

    The deterioration of concrete by alkali-silica reaction of aggregates (ASR) and the effect of nuclear radiations on the ASR have been reviewed based on our studies on the mechanism of ASR and the effect of nuclear radiations on the resistivity of minerals to alkaline solution. It has been found that the ASR is initiated by the attack of alkaline solution in concrete to silicious aggregates to convert them into hydrated alkali silicate. The consumption of alkali hydroxide by the aggregates induces the dissolution of Ca 2+ ions into the solution. The alkali silicate surrounding the aggregates then reacts with Ca 2+ ions to convert to insoluble tight and rigid reaction rims. The reaction rim allows the penetration of alkaline solution but prevents the leakage of viscous alkali silicate, so that alkali silicate generated afterward is accumulated in the aggregate to give an expansive pressure enough for cracking the aggregate and the surrounding concrete. The effect of nuclear radiation on the reactivity of quartz and plagioclase, a part of major minerals composing volcanic rocks as popular aggregates, to alkaline solution has been examined for clarifying whether nuclear radiations accelerates the ASR. It has been found that the irradiation of these minerals converts them into alkali-reactive amorphous ones. The radiation dose for plagioclase is as low as 10 8 Gy, which suggests that the ASR of concrete surrounding nuclear reactors is possible to be accelerated by nuclear radiation. (author)

  7. Impact of Aggregate Gradation and Filler Type on Marshall Properties of Asphalt Concrete

    Directory of Open Access Journals (Sweden)

    saad I. Sarsam

    2015-09-01

    Full Text Available As asphalt concrete wearing course (ACWC is the top layer in the pavement structure, the material should be able to sustain stresses caused by direct traffic loading. The objective of this study is to evaluate the influence of aggregate gradation and mineral filler type on Marshall Properties. A detailed laboratory study is carried out by preparing asphalt mixtures specimens using locally available materials including asphalt binder (40-50 penetration grade, two types of aggregate gradation representing SCRB and ROAD NOTE 31 specifications and two types of mineral filler including limestone dust and coal fly ash. Four types of mixtures were prepared and tested. The first type included SCRB specification and limestone dust, the second type included SCRB specification and coal fly ash, the third types included ROAD NOTE 31 specification and limestone dust and the fourth type included ROAD NOTE 31 specification and coal fly ash. The optimum asphalt content of each type of mixtures was determined using Marshall Method of mix design. 60 specimen were prepared and tested with dimension of 10.16 cm in diameter and 6.35 cm in height. Results of this study indicated that aggregate gradation and filler type have a significant effect on optimum asphalt content and Marshall Properties. From the experimental data, it was observed that the value of Marshall Stability is comparatively higher when using fly ash as filler as compared to limestone dust.

  8. Pervious Concrete

    OpenAIRE

    Torsvik, Øyvind André Hoff

    2012-01-01

    Pervious concrete is a material with a high degree of permeability but generally low strength. The material is primarily used for paving applications but has shown promise in many other areas of usage. This thesis investigates the properties of pervious concrete using normal Norwegian aggregates and practices. An overview of important factors when it comes to designing and producing pervious concrete is the result of this investigation. Several experiments have been performed in the concrete ...

  9. Influence of sand to coarse aggregate ratio on the interfacial bond strength of steel fibers in concrete for nuclear power plant

    International Nuclear Information System (INIS)

    Kim, Jung Jin; Kim, Dong Joo; Kang, Su Tae; Lee, Jang Hwa

    2012-01-01

    Highlights: ► The final goal is to develop a fiber reinforced concrete for containment buildings. ► We investigated the effect of S/a on the bond strength of steel fibers. ► Deformed steel fibers produced much higher interfacial bond strength. ► As S/a increased, twisted fiber showed a significant enhancement in bond strength. ► Smooth and hooked fiber showed no clear difference as S/a increased. - Abstract: The interfacial bond strength of three high strength steel fibers (smooth, hooked, and twisted fiber) in concrete of nuclear power plants was investigated to develop fiber reinforced concrete for containment building. Sand to aggregate ratio (S/a) was adjusted to compensate reduction in the workability due to adding fibers; the influence of S/a ratio on the interfacial bond strength was investigated. As the S/a ratio increased from 0.444 to 0.615, the bond strength of twisted steel fiber was significantly improved while smooth and hooked steel fiber showed no clear difference. The different sensitivity according to the S/a ratio results from the different pullout mechanism: twisted steel fiber generates more mechanical interaction during fiber pullout at the interface between fiber and matrix than smooth and hooked fibers. The microscopic observation by scanning electron microscope back-scattered electrons images discovered lower porosity at the interfacial transition zone between fiber and concrete with higher S/a ratio.

  10. Influence of sand to coarse aggregate ratio on the interfacial bond strength of steel fibers in concrete for nuclear power plant

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jung Jin, E-mail: jjinslow@nate.com [Department of Civil and Environmental Engineering, SeJong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Kim, Dong Joo, E-mail: djkim75@sejong.ac.kr [Department of Civil and Environmental Engineering, SeJong University, 98 Gunja-Dong, Gwangjin-Gu, Seoul 143-747 (Korea, Republic of); Kang, Su Tae, E-mail: stkang@daegu.ac.kr [Department of Civil Engineering, Daegu University, 201 Daegudae-ro, Jillyang, Gyeongsan, Gyeongbuk 712-714 (Korea, Republic of); Lee, Jang Hwa, E-mail: jhlee@kict.re.kr [Korea Institute of Construction Technology, 2311 Daewha-Dong, Ilsan-Gu, Goyang-Si, Gyeonggi-Do 411-712 (Korea, Republic of)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The final goal is to develop a fiber reinforced concrete for containment buildings. Black-Right-Pointing-Pointer We investigated the effect of S/a on the bond strength of steel fibers. Black-Right-Pointing-Pointer Deformed steel fibers produced much higher interfacial bond strength. Black-Right-Pointing-Pointer As S/a increased, twisted fiber showed a significant enhancement in bond strength. Black-Right-Pointing-Pointer Smooth and hooked fiber showed no clear difference as S/a increased. - Abstract: The interfacial bond strength of three high strength steel fibers (smooth, hooked, and twisted fiber) in concrete of nuclear power plants was investigated to develop fiber reinforced concrete for containment building. Sand to aggregate ratio (S/a) was adjusted to compensate reduction in the workability due to adding fibers; the influence of S/a ratio on the interfacial bond strength was investigated. As the S/a ratio increased from 0.444 to 0.615, the bond strength of twisted steel fiber was significantly improved while smooth and hooked steel fiber showed no clear difference. The different sensitivity according to the S/a ratio results from the different pullout mechanism: twisted steel fiber generates more mechanical interaction during fiber pullout at the interface between fiber and matrix than smooth and hooked fibers. The microscopic observation by scanning electron microscope back-scattered electrons images discovered lower porosity at the interfacial transition zone between fiber and concrete with higher S/a ratio.

  11. Innovative process routes for a high-quality concrete recycling.

    Science.gov (United States)

    Menard, Y; Bru, K; Touze, S; Lemoign, A; Poirier, J E; Ruffie, G; Bonnaudin, F; Von Der Weid, F

    2013-06-01

    This study presents alternative methods for the processing of concrete waste. The mechanical stresses needed for the embrittlement of the mortar matrix and further selective crushing of concrete were generated by either electric impulses or microwaves heating. Tests were carried out on lab-made concrete samples representative of concrete waste from concrete mixer trucks and on concrete waste collected on a French demolition site. The results obtained so far show that both techniques can be used to weaken concrete samples and to enhance aggregate selective liberation (that is the production of cement paste-free aggregates) during crushing and grinding. Electric pulses treatment seems to appear more efficient, more robust and less energy consuming (1-3 kWh t(-1)) than microwave treatment (10-40 kWh t(-1)) but it can only be applied on samples in water leading to a major drawback for recycling aggregates or cement paste in the cement production process. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Desempenho de concretos com agregados reciclados de cerâmica vermelha Performance of red ceramic recycled aggregate concrete

    Directory of Open Access Journals (Sweden)

    A. E. B. Cabral

    2009-12-01

    do concreto, sendo que o agregado do tipo graúdo reciclado exerceu em todas as propriedades, uma maior influência.Construction and Demolition (C&D waste is an important portion of solid waste produced in Brazilian cities, corresponding around 50% of urban solid wastes. Among several representatives of C&D waste, red ceramic, originated from bricks and tiles used in constructions, is a considerable portion. The recycling of C&D waste making recycled aggregates has been a common practice, particularly in cities where there is an inaccessibility or shortage of natural aggregates, that propitiate high costs to acquire them. Intending determine the behavior of red ceramic recycled aggregates in concrete's production, it was made an experimental program based on a project of experiments. In this program, the fine and the coarse natural aggregates were substituted by theirs respective recycled aggregates. The water/cement ratio was also varied. The produced concretes were analyzed regarding three properties: axial strength, modulus of deformation and volume of permeable voids (VPP. All the proposed models had excellent determination coefficient, higher than 95%. Simulations were made using the proposed models. The results indicate the natural fine aggregate substitution by the recycled red ceramic fine aggregate results in an axial strength increment and for a natural coarse aggregate substitution by the recycled red ceramic coarse aggregate, a decrease. For the other concrete properties, it was observed that the recycled aggregate use, as for coarse as for fine aggregate, had a negative effect and the recycled coarse aggregate exercised a larger influence than the fine aggregate.

  13. Study of local Agregate for Gamma radiation concrete shield; Studi pemakaian Agregat lokal pada pembuatan beton perisai radiasi Gamma

    Energy Technology Data Exchange (ETDEWEB)

    Tochrul-Binowo,; Endro-Kismolo,; Darsono, [Yogyakarta Nuclear Research Centre, National Atomic Energy Agency, Yogyakarta (Indonesia)

    1996-04-15

    Investigation on the composition of gamma radiation concrete shield made of local barite, manganese fine and coarse aggregates from Kulon Progo, Yogyakarta has been done. The purpose of the research was to find out the quality of these local material for an aggregate of gamma radiation concrete shield. The research was done where each mineral was used as coarse aggregate and the fine aggregate from Kulon Progo was used as fine basic aggregate. Firstly a normal concrete was made by mixing cement, fine aggregate, coarse aggregate and water at a weight ratio of cement: fine aggregate: coarse: water 1: 2.304: 3.456: 0.58. The gamma radiation absorption capacity of the concrete tested by using Cs-137 as source standard. The same method was done on barite concrete at the weight ratio of cement: fine aggregate: barite aggregate: water 1: 2.303: 3.456: 0.58 and manganese concrete at the weight ratio of cement: fine aggregate: manganese aggregate: and water 1: 1.896: 2.844: 0.58. The result of the study showed that the gamma radiation absorption capacity of barite aggregate was greater than that of normal concrete and manganese concrete. The coefficient linear attenuation (for 6.0 cm thickness) of each concrete were {mu} barite concrete = 0.23071 cm{sup -1}, {mu} manganese concrete = 0.08401 cm{sup -1} and {mu} normal concrete = 0.1669 cm{sup -1}.

  14. Separation of contaminated concrete

    International Nuclear Information System (INIS)

    Bakiewicz, J.L.; Reymer, A.P.S.

    1990-01-01

    Separating the contaminated parts from the non-contaminated parts from decommissioned nuclear facilities may strongly reduce the amount of contaminated concrete. The reduction in volume of the radioactive contaminated concrete is dependent on how much cementstone is in the concrete. This research program shows that the radioactive contamination is mostly in the cementstone. However the choice that the cementstone parts, (or better said the radioactive parts) are smaller than 1 mm may not always be true. Normally the cementstone takes about 30% of the total concrete volume. A separation procedure composed by a combination of milling and thermal shock has been assessed. Both the cold and hot thermal shock in combination with milling are not able to separate the cementstone from the larger aggregates completely. However, the cementstone from the concrete with a low nominal grain size seems to be almost completely removed by the combination cold thermal shock/milling, while the cementstone from the concrete with a high nominal grain size seems to be almost completely removed by the combination hot thermal shock/milling. After both methods a layer of cementstone was still visible on the aggregates. Washing followed by a nitric acid treatment removed each 2 wt% of cementstone

  15. Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

    Energy Technology Data Exchange (ETDEWEB)

    Naus, Dan J [ORNL

    2007-02-01

    The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adverse performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program.

  16. Primer on Durability of Nuclear Power Plant Reinforced Concrete Structures - A Review of Pertinent Factors

    International Nuclear Information System (INIS)

    Naus, Dan J.

    2007-01-01

    The objective of this study was to provide a primer on the environmental effects that can affect the durability of nuclear power plant concrete structures. As concrete ages, changes in its properties will occur as a result of continuing microstructural changes (i.e., slow hydration, crystallization of amorphous constituents, and reactions between cement paste and aggregates), as well as environmental influences. These changes do not have to be detrimental to the point that concrete will not be able to meet its performance requirements. Concrete, however, can suffer undesirable changes with time because of improper specifications, a violation of specifications, or adverse performance of its cement paste matrix or aggregate constituents under either physical or chemical attack. Contained in this report is a discussion on concrete durability and the relationship between durability and performance, a review of the historical perspective related to concrete and longevity, a description of the basic materials that comprise reinforced concrete, and information on the environmental factors that can affect the performance of nuclear power plant concrete structures. Commentary is provided on the importance of an aging management program

  17. Development of treatment technology for radioactive concrete wastes

    Energy Technology Data Exchange (ETDEWEB)

    Min, B. Y.; Choi, W. K.; Lee, K. W., E-mail: bymin@kaeri.re.k [Korea Atomic Energy Research Institute, 1045 Daeduk-daero, Yuseong-gu, Daejeon, 305-353 Republic of Korea (Korea, Republic of)

    2010-10-15

    The aim of this study was the separation of clean aggregates from contaminated dismantling concrete wastes by thermal and mechanical processes. In Korea, the decontamination and decommissioning of the retired Korea research reactor (KRR) and a uranium conversion plant (UCP) at the Korea Atomic Energy Research Institute (KAERI) has been under way. Hundreds of tons of concrete wastes are expected from these facilities. The KAERI has developed volume reduction technology applicable to an activated heavy concrete waste generated by dismantling KRR-2 and a uranium contaminated light weight concrete produced from a UCP. Contamination level of the gravel and sand aggregates was remarkably decreased by thermal and mechanical process. The volume reduction rate could be achieved above 70% for KRR-2 concrete waste and above to 80% for the UCP concrete waste. (Author)

  18. Mechanical properties of GFRP tube confined recycled concrete under axial compression

    International Nuclear Information System (INIS)

    Wang, Xiaogang; Liang, Chaofeng; Zhou, Zechenglong; Dong, Lanqi; Ding, Kewei; Huang, Jialun

    2015-01-01

    This article outlines the recycled aggregate replacement rate and thick-diameter rate of GFRP tube confined in recycled concrete, which has an important impact on the material's compressive strength. Overall, under the same conditions of using recycled concrete, the bearing capacity of short concrete columns can be improved by using broader GFRP tubes. There is a four-fold increase in the bearing capacity of short concrete columns compared to the short column without the restriction of a GFRP tube. The bearing capacity of a short column crafted by recycled coarse aggregate is much lower (about 30%). than those made by common concrete column Additionally, the bearing capacity of short columns made by recycled fine aggregates is also lower than those made by common concrete (approximately 20%). Finally, we find that there is no significant difference between experimental and theoretical data. (paper)

  19. Workability and Compressive Strength for Concrete With Coconut Shell Aggregate

    Directory of Open Access Journals (Sweden)

    Leman Alif Syazani

    2017-01-01

    Full Text Available This study was conducted to investigate the compressive strength and workability of concrete added with coconut shells. Comparisons were made between conventional concrete with concrete mix coconut shell. In this study, the concretes were mixes with coconut shell by percentage of weight concrete which is 0%, 5%, and 10%. The coconut shell has been crushed first, then it was sieved, to get the optimum size which, that retained on the 5mm sieve and passing 10mm sieve. Experimental tests conducted in this study are slump test and compressive test. The results from this study are workability of concrete added with 0% and 5% of coconut shell has medium degree of workability compared to concrete added with 10% that has low workability. For the compressive strength, the concrete added with 5% and 10% of coconut shell has lower strength compared with normal concrete.

  20. Study on Basic Characteristics for the Development of Radiation Shielding High-Weight Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Mun, Young Bum; Lee, Jea Hyung; Choi, Hyun Kook [Sungshin Cement CO., Sejong (Korea, Republic of); Oh, Jeong Hwan; Choi, Soo Seok [Jeju National University, Jeju (Korea, Republic of)

    2016-05-15

    It is planned to build a power plant more than 6 units. Although the demand of a nuclear power plant is going to increase, the attention for radiation shielding is relatively in a low level. Concrete is one of the excellent and widely used shielding materials. Since the radiation shielding of a given material is proportional to density and thickness, a high-weight concrete with high-weight aggregate which is higher than normal concrete is used for radiation shielding. However, there are a few studies and references about radiation shielding concrete. Therefore, it is required to find a high-weight aggregate. The purpose of this paper is the development of a highweight concrete to improve radiation shielding capability. The radiation shielding rate of high-weight concrete is higher than that of reference concrete. It is confirmed that the density of aggregate and the unit weight of concreate is proportional to the radiation shielding rate. In addition, the chemical composition of aggregate has also has an important effect on γ-ray shielding. Therefore, high weight aggregates of higher density are essentially required to improve radiation shielding capability. The compressive strength of a high weight concrete is better than that of reference concrete. Slump and air contents, however, are slightly increased with by-product aggregates.

  1. Testing program for concrete at temperatures to 8940K

    International Nuclear Information System (INIS)

    Naus, D.J.; Oland, C.B.; Robinson, G.C.

    1981-01-01

    A test program was conducted to define the variations in mechanical properties of a limestone aggregate concrete and a lightweight insulating concrete exposed to elevated temperatures. Four test series were conducted: (1) unconfined compression; (2) shear; (3) rebar bond; and (4) sustained loading (creep). Tests results are presented

  2. Utilization of crushed radioactive concrete for mortar to fill waste container void space

    International Nuclear Information System (INIS)

    Ishikura, Takeshi; Ohnishi, Kazuhiko; Oguri, Daiichiro; Ueki, Hiroyuki

    2004-01-01

    Minimizing the volume of radioactive waste generated during dismantling of nuclear power plants is a matter of great importance. In Japan waste forms buried in a shallow burial disposal facility as low level radioactive waste must be solidified by cement or other materials with adequate strength and must provide no harmful opening. The authors have developed an improved method to minimize radioactive waste volume by utilizing radioactive concrete for fine aggregate for mortars to fill void space in waste containers. Tests were performed with pre-placed concrete waste and with filling mortar using recycled fine aggregate produced from concrete. It was estimated that the improved method substantially increases the waste fill ratio in waste containers, thereby decreasing the total volume of disposal waste. (author)

  3. Recycling of concrete generated from Nuclear Power Plant dismantling

    International Nuclear Information System (INIS)

    Ogawa, Hideo; Nawa, Toyoharu; Ishikura, Takeshi; Tanaka, Hiroaki

    2013-01-01

    Reactor decommissioning required various technologies such as dismantling of facilities, decontamination, radioactivity measurement and recycling of dismantling wastes. This article discussed recycling of demolished concrete wastes. Dismantling of reactor building of large one unit of nuclear power plants would generate about 500 K tons of concrete wastes, about 98% of which was non-radioactive and could be used as base course material or backfill material after crushed to specified particle size. Since later part of 1990s, high quality recycled aggregate with specified limit of bone-dry density, water absorptivity and amount of fine aggregate had been developed from demolished concrete with 'Heat and rubbing method', 'Eccentric rotor method' and 'Screw grinding method' so as to separate cements attached to aggregate. Recycled aggregates were made from concrete debris with 'Jaw crusher' to particle size less than 40 mm and then particle size control or grinded by various grinding machines. Recycled fine aggregates made from crushing would have fragile site with cracks, air voids and bubbles. The author proposed quality improvement method to selectively separate fragile defects from recycled aggregates using weak grinding force, leaving attached pastes much and preventing fine particle generation as byproducts. This article outlined experiments to improve quality of recycled fine aggregates and their experimental results confirmed improvement of flow ability and compressive strength of mortal using recycled fine aggregates using 'Particle size selector' and 'Ball mill' so as to remove their fragile parts less than 2%. Mortal made from recycled fine aggregate could also prevent permeation of chloride ion. Recycled aggregate could be used for concrete instead of natural aggregate. (T. Tanaka)

  4. Deformation Behavior of Recycled Concrete Aggregate during Cyclic and Dynamic Loading Laboratory Tests

    Directory of Open Access Journals (Sweden)

    Wojciech Sas

    2016-09-01

    Full Text Available Recycled concrete aggregate (RCA is a relatively new construction material, whose applications can replace natural aggregates. To do so, extensive studies on its mechanical behavior and deformation characteristics are still necessary. RCA is currently used as a subbase material in the construction of roads, which are subject to high settlements due to traffic loading. The deformation characteristics of RCA must, therefore, be established to find the possible fatigue and damage behavior for this new material. In this article, a series of triaxial cyclic loading and resonant column tests is used to characterize fatigue in RCA as a function of applied deviator stress after long-term cyclic loading. A description of the shakedown phenomenon occurring in the RCA and calculations of its resilient modulus (Mr as a function of fatigue are also presented. Test result analysis with the stress-life method on the Wohler S-N diagram shows the RCA behavior in accordance with the Basquin law.

  5. Effect of presaturation and seawater on strength and durability of lightweight concrete

    International Nuclear Information System (INIS)

    Haque, M.N.

    2009-01-01

    The internal curing is provided, usually, by the use of some proprietary fine aggregates which provide sufficient water from within to promote the ongoing hydration of cement and hence result in a relatively high performance concrete. Two concretes, one total lightweight concrete (TLWC) and the second sand lightweight concrete (SLWC) of 28 day cube strength of approximately 40 MPa (5800 psi) were designed. A total of six mixes were cast out of these two concretes, 4-TLWC's and 2-SLWC's. The variation in the mixes was due to moisture condition of the aggregates and the use of seawater in mixing and curing of the concretes. The effect of these variations on the cube compressive strength, water permeability, sulphate and chloride content, depth of carbonation and shrinkage of these six concretes was studied. The presaturation of the lightweight aggregates (LWA's used do not seem to have improved the compressive strength, and water permeability of these concretes. The drying shrinkage strains of the concrete using pre saturated aggregates decreased considerably. The application of seawater in making and curing these LWC's increased the compressive strength by about 15%. (author)

  6. Non destructive Testing (NDT) of concrete containing hematite

    International Nuclear Information System (INIS)

    Mohamad Pauzi Ismail; Noor Azreen Masenwat; Suhairy Sani; Nasharuddin Isa; Mohamad Haniza Mahmud

    2014-01-01

    This paper described the results of Non-destructive ultrasonic and rebound hammer measurements on concrete containing hematite. Local hematite stones were used as aggregates to produce high density concrete for application in X-and gamma shielding. Concrete cube samples (150 mm x 150 mm x 150 mm) containing hematite as coarse aggregates were prepared by changing mix ratio, water to cement ratio (w/c) and types of fine aggregate. All samples were cured in water for 7 days and then tested after 28 days. Density, rebound number(N) and ultrasonic pulse velocity (UPV) of the samples were taken before compressed to failure. The measurement results are explained and discussed. (author)

  7. Flexural strengthening of reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted GFRP bars

    Energy Technology Data Exchange (ETDEWEB)

    Tang, W.C.; Balendran, R.V.; Nadeem, A.; Leung, H.Y. [City University of Hong Kong (China). Department of Building and Construction

    2006-10-15

    Application of near-surface mounted (NSM) fibre reinforced polymer (FRP) bars is emerging as a promising technology for increasing flexural and shear strength of deficient reinforced concrete (RC) members. In order for this technique to perform effectively, the structural behaviour of RC elements strengthened with NSM FRP bars needs to be fully characterized. This paper focuses on the characterization of flexural behaviour of RC members strengthened with NSM glass-FRP bars. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam tests were type of concretes (lightweight polystyrene aggregate concrete and normal concrete), type of reinforcing bars (GFRP and steel), and type of adhesives. Flexural performance of the tested beams including modes of failure, moment-deflection response and ultimate moment capacity are presented and discussed in this paper. Results of this investigation showed that beams with NSM GFRP bars showed a reduction in ultimate deflection and an improvement in flexural stiffness and bending capacity, depending on the PA content of the beams. In general, beams strengthened with NSM GFRP bars overall showed a significant increase in ultimate moment ranging from 23% to 53% over the corresponding beams without NSM GFRP bars. The influence of epoxy type was found conspicuously dominated the moment-deflection response up to the peak moment. Besides, the ultimate moment of concrete beams reinforced with GFRP bars could be predicted satisfactorily using the equation provided in ACI 318-95 Building Code. (author)

  8. Maintenance and preservation of concrete structures. Report 3: Abrasion-erosion resistance of concrete

    Science.gov (United States)

    Liu, T. C.

    1980-07-01

    This report describes a laboratory test program on abrasion-erosion resistance of concrete, including the development of a new underwater abrasion-erosion test method. This program was designed to evaluate the relative abrasion-erosion resistance of various materials considered for use in the repair of erosion-damaged concrete structures. The test program encompassed three concrete types (conventional concrete, fiber-reinforced concrete, and polymer concrete); seven aggregate types (limestone, chert, trap rock, quartzite, granite, siliceous gravel, and slag); three principal water-cement rations (0.72, 0.54, and 0.40); and six types of surface treatment (vacuum, polyurethane coating, acrylic mortar coating, epoxy mortar coating, furan resin mortar coating, and iron aggregate topping). A total of 114 specimens made from 41 batches of concrete was tested. Based on the test data obtained, a comprehensive evaluation of the effects of various parameters on the abrasion-erosion resistance of concrete was presented. Materials suitable for use in the repair of erosion-damaged concrete structures were recommended. Additional work to correlate the reported findings with field performance was formulated.

  9. The cause and influence of self-cementing properties of fine recycled concrete aggregates on the properties of unbound sub-base

    International Nuclear Information System (INIS)

    Poon, C.-S.; Qiao, X.C.; Chan, Dixon

    2006-01-01

    The use of coarse recycled concrete aggregates (CRCA) in conjunction with fine recycled concrete aggregates (FRCA) as sub-base materials has been widely studied. Although research results indicate that it is feasible to employ both CRCA and FRCA as granular sub-base, the influence of the unhydrated cement in the adhered mortar of the RCA on the properties of the sub-base materials has not been thoroughly studied. Generally, it is known that the strength of the sub-base materials prepared with RCA increases over time. However, this mechanism, known as the self-cementing properties, is not well understood and is believed to be governed by the properties of the fine portion of the RCA (<5 mm). This paper presents an investigation on the cause of the self-cementing properties by measuring X-ray diffraction patterns, pH values, compressive strength and permeability of various size fractions of the FRCA obtained from a commercially operated construction and demolition waste recycling plant. Their influence on the overall sub-base materials was determined. The results indicate that the size fractions of <0.15 and 0.3-0.6 mm (active fractions) were most likely to be the principal cause of the self-cementing properties of the FRCA. However, the effects on the properties of the overall RCA sub-base materials were minimal if the total quantity of the active fractions was limited to a threshold by weight of the total fine aggregate

  10. HIGH-QUALITY ORNAMENTAL FINE CONCRETES MODIFIED BY NANOPARTICLES OF TITANIUM DIOXIDE

    Directory of Open Access Journals (Sweden)

    Bazhenov Yuriy Mikhaylovich

    2012-10-01

    Full Text Available Ultrasonic method of generation of a stable suspension of nano-particles of titanium dioxide and the strengthening properties of the ornamental fine concrete that contains cement binders with a nano-dispersed additive constitute the subject of the research covered by the authors. Nanoparticles react with the basic chemical elements that compose the concrete and act as crystallization centres. Therefore, the concrete porosity is reduced, while physical and technology-related properties of the ornamental fine concrete are improved. The authors have proven that the application of the nano-dispersed additive that contains titanium dioxide influences the processes of the structure formation in respect of fine ornamental concretes and improves the strength, as well as the water and cold resistance of fine concretes. The improvement is attributed to the dense concrete structure and strong adhesion between cement grains and between the cement and the aggregate. This conclusion is based on the data obtained through the employment of an electronic microscope used to identify the porosity of fine concretes.

  11. Utilization of crushed clay brick in concrete industry

    Directory of Open Access Journals (Sweden)

    Ali A. Aliabdo

    2014-03-01

    Full Text Available A comprehensive experimental program regarding the use of recycled aggregates produced from demolition of brick buildings is presented. The brick wastes were crushed, sorted and classified into coarse and fine aggregates as well as powder (CBP. The first phase of the research focuses on the effect of incorporating recycled aggregates on physico-mechanical properties of paste, mortar and concrete. Non-traditional tests including X-ray diffraction (XRD, thermo-gravimetric analysis (TGA and micro-structural analysis (MSA were performed. The second phase of the program explores the effect of using recycled aggregates on properties of concrete masonry units. A total of 44 mixtures were utilized throughout the program. Results show cement paste when modified with 25% CBP achieves smaller pore size and lower weight loss under high temperature than reference paste. Furthermore, the use of recycled aggregates reduces the overall unit weight of concrete masonry units. Actually, modified concrete masonry units incorporating recycled aggregates achieve lower unit weight, higher thermal resistance and absorption rate than reference units. Although considerable strength reduction is noticeable by substitution, compressive strength levels meet the Egyptian specifications limitations. Critical replacement ratios are suggested to produce load bearing-concrete masonry units. Based on experimental evidences, it can be stated that the use of recycled aggregate and dust made of clay bricks is promising in many applications where the thermal resistance, cost and environmental aspects are imperative.

  12. Combined Non-destructive Testing (NDT) methods for evaluating concrete quality

    International Nuclear Information System (INIS)

    Mohamad Pauzi Ismail; Noor Azreen Masenwat; Suhairy Sani; Nasharuddin Isa; Mohamad Haniza Mahmud

    2014-01-01

    This paper described the results of combining Non-destructive measurements on concrete. Local crushed granite and hematite were used as coarse aggregates; mining sand and river sand were used as fine aggregates to produce various density and strength of concrete. Concrete samples (150 mm cubes and interlocked blocks) were prepared by changing mix ratio, water to cement ratio (w/c) and types of aggregates. Density, rebound number(N) and ultrasonic pulse velocity (UPV) of the samples were taken before compressed to failure. The measurement results are explained and discussed. (author)

  13. Study on the Effect of Straw Fiber on the Performance of Volcanic Slag Concrete

    Science.gov (United States)

    Xiao, Li-guang; Liu, Xi-xu

    2018-03-01

    In this paper, the effects of straw fiber on the working performance, mechanical properties and frost resistance of volcanic slag lightweight aggregate concrete were studied. The experimental results show that the straw fiber is subjected to surface carbonization treatment and mixed into the volcanic slag light aggregate concrete. The flexural strength and fracture pressure ratio of volcanic slag lightweight aggregate concrete are improved obviously Improved volcanic slag lightweight aggregate concrete brittleness improves toughness. Carbonized straw fiber greatly improves the frost resistance of volcanic slag lightweight aggregate concrete. So that the volcanic slag light aggregate concrete freeze-thaw cycle can reach 300 times.

  14. Proportioning of light weight concrete

    DEFF Research Database (Denmark)

    Palmus, Lars

    1996-01-01

    Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory......Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory...

  15. Investigation of the impact of nanotechnology on the freeze-thaw durability of concrete containing d-cracking aggregates : [technical summary].

    Science.gov (United States)

    2015-05-01

    Freezing and thawing damage is the most common cause of distress in : Kansas pavements. Many locally available aggregates in Kansas do not : meet current standards for use in concrete pavements because of poor : freeze-thaw durability. The use of nan...

  16. Using recycled concrete in MDOT's transportation infrastructure : manual of practice.

    Science.gov (United States)

    2011-08-01

    "Crushed concrete aggregate (CCA) is granular material manufactured by removing, crushing, and : processing old concrete for reuse as an aggregate source in new construction. Although the Michigan : Department of Transportation (MDOT) has used CCA si...

  17. Design of Normal Concrete Mixtures Using Workability-Dispersion-Cohesion Method

    Directory of Open Access Journals (Sweden)

    Hisham Qasrawi

    2016-01-01

    Full Text Available The workability-dispersion-cohesion method is a new proposed method for the design of normal concrete mixes. The method uses special coefficients called workability-dispersion and workability-cohesion factors. These coefficients relate workability to mobility and stability of the concrete mix. The coefficients are obtained from special charts depending on mix requirements and aggregate properties. The method is practical because it covers various types of aggregates that may not be within standard specifications, different water to cement ratios, and various degrees of workability. Simple linear relationships were developed for variables encountered in the mix design and were presented in graphical forms. The method can be used in countries where the grading or fineness of the available materials is different from the common international specifications (such as ASTM or BS. Results were compared to the ACI and British methods of mix design. The method can be extended to cover all types of concrete.

  18. Assessment of Fine Aggregates from Different Sources in Ibadan and Environs for Concrete Production

    Directory of Open Access Journals (Sweden)

    W. O. Ajagbe

    2018-03-01

    Full Text Available Assessment of natural sand being used as fine aggregate for concrete production in Ibadan and its environs was carried out. Ten sources (F1 – F10 were selected for the study; four (F5, F6, F7, F8 were river sand sources while six (F1, F2, F3, F4, F9, F10 were burrow pit sand sources. Samples from each source were subjected to sieve analysis, atterberg limit, bulk density, specific gravity, water absorption, sand equivalent, clay lumps and friable particles, amount of materials passing 75μm and organic impurities adopting ASTM standard procedures. Results revealed that sand from river sources met all the criteria for concrete production stated in ASTM standard while sand from burrow pits deviated from limits of the standard in some respects. F10 had water absorption of 2.6% which exceeded maximum 2% specified, F9 was not free from clay lumps and friable particles with a significant value of 6% as against 3% maximum specification. F1, F2, F3, F4, F9 and F10 have more amounts of materials passing the 75μm sieve ranging from 10.8% for F9 to 20.1% for F10 than maximum of 5% in standard specification while F1, F9 and F10 showed an indication of having organic impurities. It is recommended that performance test be conducted on concrete made from burrow pits sand before use for concrete production. The knowledge of this study can be used as a prospecting tool for selecting suitable sand for the production of quality concrete.

  19. Reuse of municipal solid wastes incineration fly ashes in concrete mixtures.

    Science.gov (United States)

    Collivignarelli, Carlo; Sorlini, Sabrina

    2002-01-01

    This study is aimed at assessing the feasibility of concrete production using stabilized m.s.w. (municipal solid waste) incineration fly ashes in addition to natural aggregates. The tested fly ashes were washed and milled, then stabilized by a cement-lime process and finally were reused as a "recycled aggregate" for cement mixture production, in substitution of a natural aggregate (with dosage of 200-400 kg m(-3)). These mixtures, after curing, were characterized with conventional physical-mechanical tests (compression, traction, flexure, modulus of elasticity, shrinkage). In samples containing 200 kg(waste) m(-3)(concrete), a good compressive strength was achieved after 28 days of curing. Furthermore, concrete leaching behavior was evaluated by means of different leaching tests, both on milled and on monolithic samples. Experimental results showed a remarkable reduction of metal leaching in comparison with raw waste. In some cases, similar behavior was observed in "natural" concrete (produced with natural aggregates) and in "waste containing" concrete.

  20. Effect of porosity on physical properties of lightweight cement composite with foamed glass aggregate

    Directory of Open Access Journals (Sweden)

    Kurpińska Marzena

    2017-01-01

    Full Text Available This paper reports on a study of physical properties of lightweight cement composite. We investigate the possibility of replacing traditional aggregate with Granulated Ash Aggregate (GAA and above all with Granulated Expanded Glass Aggregate (GEGA. For this purpose, 15 specimens of different percentage share of each aggregate in total aggregate volume were tested: 0%, 25%, 50%, 75% or 100% of foam glass aggregate (GEGA partially replaced by ash aggregate (GAA content in the cement composite. The water-cement ratio was constant and equal to w/c=0.5. Three grain sizes were analyzed: 2mm, 4mm (both GEGA and 8mm (GAA. Numerical simulations of concrete specimen behavior under static loading were conducted with the implementation of elastic plastic model of each component. The study shows a significant impact of grain type and size on physical properties of lightweight concrete. Due to lower density of foamed glass aggregate, specimens shows various apparent density and porosity, which affect concrete properties. Compressive strength of concrete decreases with the increase in foam glass aggregate content; however specimens show different workability and in consequence porosity of lightweight concrete.