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Sample records for aggregates by relationship to concrete

  1. Alkali silica reaction in concrete induced by mortar adhered to recycled aggregate

    Etxeberria, M.; Vázquez, E.

    2010-01-01

    The durability of recycled concrete must be determined before this material can be used in construction. In this paper the alkali-silica reaction in recycled concrete is analyzed. The recycled concrete is made with recycled aggregates, composed by original limestone aggregates and adhered mortar with reactive silica sand, and high alkali content cement. Due to the manufacturing process used for concrete production and the high water absorption capacity of recycled aggregates, cement accumulat...

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

    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. PMID:17764837

  3. Recycled aggregate concrete exposed to elevated temperature

    Arundeb Gupta; Saroj Mandal; Somnath Ghosh

    2012-01-01

    An experimental investigation has been conducted to study the mechanical as well as micro structural properties of Recycled aggregate concrete (RAC) exposed to elevated temperature. Fly ash (as replacement of cement) was added while making concrete. Recycled aggregates are mixed with natural aggregates also to prepare concrete. Cubes and cylinder test specimens were prepared and cured under water for 28 days. Test specimens were exposed to different levels of temperature (200oC, 400oC, 600oC,...

  4. Repercussions on concrete permeability due to recycled concrete aggregate

    Gómez Soberón, José Manuel Vicente; Agulló Fité, Luís; Vázquez Ramonich, Enric

    2001-01-01

    This paper presents an experimental analysis of recycled concrete (RC) in which the natural aggregates are replaced by recycled concrete aggregates (RCA). This experimental program covers the specifications of the aggregates employed, together with that of the concrete that is manufactured with them. The considerable effect on the permeability of RC that is produced by the use of RCA is described and discussed. Tests reveal considerable increase in permeability of RC in compari...

  5. Relationship between gas adsorption and the shrinkage and creep of recycled aggregate concrete

    Gómez Soberón, José Manuel Vicente

    2003-01-01

    This is a preprint of an article published in Gómez-Soberón,José M.V. Relationship between gas adsorption and the shrinkage and creep of recycled aggregate concrete. "Cement, concrete and aggregates". 2003,25(2), p. 42-48. In this work, it is described an experimental analysis of specimens of recycled concrete (RC) with replacement of natural aggregate with recycled aggregate originating from concrete (RCA). An experimental analysis to obtain the shrinkage and creep properties (basic and b...

  6. Thermal Proprieties of Concrete Lightened by Wood Aggregates

    D. Taoukil

    2011-02-01

    Full Text Available It is about an experimental study of the thermal proprieties of a concrete lightened by wood aggregates stemming from waste products of the carpentry work. We were especially interested in the comparison between the proprieties of concretes lightened by sawdust and those lightened by wood shavings. The determination of the thermal conductivity and diffusivity of various samples allowed us to demonstrate that the incorporation of wood aggregates in the concrete increases considerably its thermal insulation capacity. Also, we found that, at equal mass percentage of wood aggregates, the concretes elaborated from shavings present thermal insulation capacities better than those obtained from sawdust. On other hand, we have examined the influence of the water content on the thermophysical properties of the studied concretes. So, we have demonstrated and confirmed that the thermal conductivity and diffusivity of the studied materials are strongly dependent on the water content.

  7. ASSESSMENT OF RECYCLED AGGREGATE CONCRETE

    Ahmad Mujahid Ahmad Zaidi

    2009-01-01

    Used of recycled aggregate (RA) in concrete can be described in environmental protection and economical terms. The application of recycled aggregate to use in construction activities have been practice by developed European countries and also of some Asian countries. This paper reports the results of an experimental study on the mechanical properties of recycled aggregate concrete (RAC) as compared to natural aggregate concrete (NAC). The effects of size of RA on compressive strength were dis...

  8. Structural Concrete Prepared with Coarse Recycled Concrete Aggregate: From Investigation to Design

    Valeria Corinaldesi

    2011-01-01

    An investigation of mechanical behaviour and elastic properties of recycled aggregate concrete (RAC) is presented. RACs were prepared by using a coarse aggregate fraction made of recycled concrete coming from a recycling plant in which rubble from concrete structure demolition is collected and suitably treated. Several concrete mixtures were prepared by using either the only virgin aggregates (as reference) or 30% coarse recycled aggregate replacing gravel and by using two different kinds of ...

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

    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. PMID:21784626

  10. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    Hisham Qasrawi; Iqbal Marie

    2013-01-01

    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...

  11. Reducing drying shrinkage of concrete by treatment of aggregate

    Kwan, AKH; Fung, WWS; Wong, HHC

    2010-01-01

    Drying shrinkage of concrete has been found to cause cracking, water leakage and other serviceability problems and is thus an important research topic. In early studies, it has been found that the shrinkage of concrete varies with the rock aggregate used. This is partly because the aggregate also shrinks and the shrinkage of aggregate is dependent on the type of rock from which the aggregate is derived. However, there have been few studies on the shrinkage of rock and how the shrinkage of agg...

  12. Concrete = aggregate, cement, water?

    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. Internal deterioration of concrete by the oxidation of pyrrhotitic aggregates

    This paper presents research results on the causes of a severe concrete deterioration, which occurred in many building foundations approximately 2 years after construction. Concrete samples were investigated with X-ray diffraction (XRD) analysis, a scanning electron microscope (SEM) and a petrographic examination performed with a stereomicroscope. It was found that the early cracking of concrete stemmed from the oxidation of the pyrrhotite found in the anorthosite aggregates used to produce the concrete. The oxidation process led to the precipitation of iron hydroxides having a higher volume than the original pyrrhotite does. The presence of micas (biotite) close to the pyrrhotite seemed to promote and accelerate the oxidation process

  14. Increase on Strengths of Hot Weather Concrete by Self-Curing of Wet Porous Aggregate

    Sampebulu’ V.

    2013-01-01

    The compressive and tensile strengths of concrete made in hot weather condition decreased due to loss of mixing water caused by high evaporation. One method to overcome the problem is the use of saturated fly ash aggregate. The water content in fly ash aggregate can flow out to the hardened cement paste to continue the hydration process. This ???self-curing??? mechanism could produce more hydration around the surface of fly ash aggregate which sub-sequently increases concrete strength. Experi...

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

    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.

  16. Natural aggregate totally replacement by mechanically treated concrete waste

    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.

  17. Recycled Concrete as Aggregate for Structural Concrete Production

    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.

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

    Chen, G.M.; Y. H. He; 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...

  19. RESIDUAL FLEXURAL STRENGTH OF RECYCLED BRICK AGGREGATE CONCRETE EXPOSED TO HIGH TEMPERATURES

    Kasi Rekha

    2015-12-01

    Full Text Available The practice of using crushed brick in concrete is picking up due to its value addition to the mechanical properties of concrete. In the present experimental investigation the brick from the demolition waste is used as a coarse aggregate to study the flexural behaviour of recycled brick aggregate (RBA concrete after exposure to high temperatures. The recycled brick aggregate is replaced to granite aggregate up to 25% by its volume to produce RBA concrete. Beam specimens of size 100mm × 100mm × 500mm were used to study the flexural strength (modulus of rupture of both RBA concrete and granite aggregate (GA concrete. Both the concretes were heated to desired temperatures from 100oC to 1000oC in an interval of 100oC for three hours in bogie hearth furnace. The residual flexural strengths of both heated RBA and GA concretes were presented in this research to study the performance of RBAconcrete at high temperatures. The RBA concrete performed better than that of GA concrete in flexure at high temperatures by exhibiting higher residual strength.

  20. Mechanical and Abrasion Resistance of Recycled Aggregates Concrete in Relation to the Cement Content

    Athanas KONIN; Mangoua David Kouadio

    2011-01-01

    This paper presents the results of an experimental investigation carried out to study the effects of cement content on the mechanical and abrasion resistance of recycled aggregates concrete. Four series of mixtures with cement content 300, 350, 400 and 450 kg/m3 were formulated. In each series, natural coarse aggregate were totally replaced with recycled aggregate that allows obtaining two types of concrete: natural aggregates concrete and recycled aggregates concrete. Compressive strength, s...

  1. A STDY ON EFFECT OF SIZE OF AGGREGATE ON COMPRESSIVE STRENGHT OF CONCRETE AND STRENGHT CHARACTERSTICS BY UTILIZATIION OF WASTE MATERIALS AS COURSE AGGREGATE IN CONCRETE

    SETTIUBATHULA RAMYA

    2015-05-01

    Full Text Available Depletion of natural resources is a common phenomenon in developing countries like India due to rapid urbanization and Industrialization involving construction of Infrastructure and other amenities. In view of this, searching for suitable other viable alternative materials for concrete so that the existing natural resources could be preserved to the possible extent, for the future generation. To investigate the effect of size of aggregate on the compressive strength of concrete an experimental program was carried out. Four different sizes of coarse aggregates were used while developing the mix design. The sizes of coarse aggregate were 25mm, 20mm, 10mm and 4.75mm. Natural sand with fineness modules of 3.48 was used as fine aggregate. Ordinary Portland cement of 43 Grade was used as binding material. Different trials of mixing of coarse aggregate were made (25 mm and 20mm, 20mm and 10mm, 10mm and 4.75mm to investigate the influence of size of aggregate on compressive strength of concrete. Cubes of size 150mmx150mmx150mm were cast in laboratory and tested in Compression Testing Machine. It was concluded that 10mm and 4.75mm aggregates showed higher compressive strength than other types of aggregates. The tests revealed that on the replacement of 20% of ceramic tiles had increased the compressive strength of 13% more than that of conventional concrete. And it was observed that optimum ceramic tiles content was 20%. It is observed that by using 10% of plastic waste in concrete ,the fatigue characteristics of modified concrete has increased than that of plain cement concrete

  2. Sustainable Concrete with Recycled Aggregate

    Kara, P

    2012-01-01

    Concretes produced with recycled aggregates are the subject of several papers recently published in the technical literature. Substitution of natural aggregates can be one of possibilities to take care of landfills and increase of CO2 emissions into the atmosphere in Latvia. Recycled aggregate is a valuable resource; value-added consumption of recycled aggregate, as replacement for virgin aggregate in concrete, can yield significant energy and environmental benefits. In present study recycled...

  3. Application of Base Force Element Method to Mesomechanics Analysis for Recycled Aggregate Concrete

    Yijiang Peng; Yinghua Liu; Jiwei Pu; Lijuan Zhang

    2013-01-01

    The base force element method (BFEM) on potential energy principle is used to analyze recycled aggregate concrete (RAC) on mesolevel. The model of BFEM with triangular element is derived. The recycled aggregate concrete is taken as five-phase composites consisting of natural coarse aggregate, new mortar, new interfacial transition zone (ITZ), old mortar, and old ITZ on meso-level. The random aggregate model is used to simulate the mesostructure of recycled aggregate concrete. The mechanics pr...

  4. The effect of fly ash to self-compactability of pumice aggregate lightweight concrete

    Murat Kurt; Abdulkadir Cüneyt Aydin; Muhammed Said Gül; Rüstem Gül; Türkay Kotan

    2015-06-01

    This paper presents the results of an experimental study on the effects of fly ash, different water/(cement + mineral additive) ratios and pumice aggregates to some physical and mechanical properties of self-compacting lightweight aggregate concrete. In this study, pumice had been used as lightweight aggregates. Several properties of self-compacting pumice aggregate lightweight concretes like the unit weight, flow diameter, T50 time, flow diameter after an hour, V-funnel time, and L-box tests, 7, 28, 90 and 180-day compressive strength, 28-day splitting tensile strength, dry unit weight, water absorption, thermal conductivity and ultrasonic pulse velocity tests were investigated. For this purpose, 18 series of concrete samples were prepared in two groups. Pumice aggregate was used as a replacement of natural aggregate, at the levels of 0, 20, 40, 60, 80, and 100% by volume. Furthermore, a second series of 100% pumice aggregate was used for the production of self-compacting lightweight aggregate concrete with constant w/(c+m) ratios as 0.35, 0.40, and 0.45 by weight. The flow diameters, T50 times, paste volumes, 28-day compressive strengths, dry unit weights and thermal conductivities of self-compacting lightweight aggregate concrete were obtained in the range of 600–800 mm, 2–8 s, 471–572 lt/m3, 9.2–53.26 MPa, 839–2156 kg/m3 and 0.321–1.508 W/mk, respectively, which satisfies not only the strength requirement of semi-structural lightweight concrete but also the flowing ability requirements and thermal conductivity requirements of self-compacting lightweight aggregate concrete.

  5. Recycled Concrete as Aggregate for Structural Concrete Production

    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...

  6. Recycled aggregates concrete: aggregate and mix properties

    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

  7. Recycled aggregate concrete; an overview

    Sorato, Renan

    2016-01-01

    The aim of this Bachelor’s thesis was to investigate whether recycled materials can be incorporated into the production of concrete without compromising the compressive strength of the concrete produced. In order to shed light on the compressive strength of concrete made from recycled materials, the thesis reviewed studies in which waste materials are utilised as recycled aggregates in the composition of concrete and presented the results of this synthesis and analysis. It was found that som...

  8. Study of Concrete by Replacing Fine Aggregate by ETP Sludge of TiO2

    Sreehari Raj

    2015-08-01

    Full Text Available The rapid increase in construction activities leads to scarcity of conventional construction materials such as cement, fine aggregate and coarse aggregate. Researches are being conducted for finding cheaper materials. In India, there are many industries producing large amount of effluent treatment plant waste sludge which leads in problems of disposal. The final destination of effluent treatment plant sludge affects the environment. So alternative option is necessary for disposing effluent treatment sludge. In this study is subjected to the effective reuse of effluent treatment plant sludge of TiO2 pigment generated from Kerala Minerals and Metals Ltd (KMML. The aim of the thesis is to determine the strength parameters of concrete with the partial replacement of fine aggregate by waste sludge from KMML. Reuse of ETP sludge in concrete is an effective option for the problem of ultimate disposal up to greater extent. In this study the fine aggregate is replaced by the ETP sludge of TiO2 with different percentages such as 5%, 10%, 15%, 20%, and 25% in M35 concrete mix. The various tests such as compression, tensile and flexural strength are conducted.

  9. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    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. Residual Mechanical Properties of Concrete Made with Crushed Clay Bricks and Roof Tiles Aggregate after Exposure to High Temperatures

    Ivana Miličević; Nina Štirmer; Ivana Banjad Pečur

    2016-01-01

    This paper presents the residual mechanical properties of concrete made with crushed bricks and clay roof tile aggregates after exposure to high temperatures. One referent mixture and eight mixtures with different percentages of replacement of natural aggregate by crushed bricks and roof tiles are experimentally tested. The properties of the concrete were measured before and after exposure to 200, 400, 600 and 800 °C. In order to evaluate the basic residual mechanical properties of concrete w...

  11. Reusing recycled aggregates in structural concrete

    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

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

    Mohammed Binhussain

    2013-10-01

    Full Text Available 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.

  13. INVESTIGATIONS ON RECYCLED CONCRETE AGGREGATE AND MSAND AS AGGREGATE REPLACEMENT IN CONCRETE

    Sridhar, U; Karthick, B

    2015-01-01

    Gigantic numbers of building and destruction trashes are produced in emerging countries like India. The clearance of these trashes is serious problem because it requires huge space. The present work is to study the properties of concrete with replacement of 50% of nature sand by manufactured sand and coarse aggregates by different proportions with recycled concrete aggregates (RCA). A mix proportion for M20 grade concrete is derived with standards confirming to IS codes. RCA was p...

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

    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.

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

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

    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 co...

  16. Residual Mechanical Properties of Concrete Made with Crushed Clay Bricks and Roof Tiles Aggregate after Exposure to High Temperatures

    Ivana Miličević

    2016-04-01

    Full Text Available This paper presents the residual mechanical properties of concrete made with crushed bricks and clay roof tile aggregates after exposure to high temperatures. One referent mixture and eight mixtures with different percentages of replacement of natural aggregate by crushed bricks and roof tiles are experimentally tested. The properties of the concrete were measured before and after exposure to 200, 400, 600 and 800 °C. In order to evaluate the basic residual mechanical properties of concrete with crushed bricks and roof tiles after exposure to high temperatures, ultrasonic pulse velocity is used as a non-destructive test method and the results are compared with those of a destructive method for validation. The mixture with the highest percentage of replacement of natural aggregate by crushed brick and roof tile aggregate has the best physical, mechanical, and thermal properties for application of such concrete in precast concrete elements exposed to high temperatures.

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

    Safiuddin

    2011-01-01

    Full Text Available 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 revealed that RCA significantly decreased the workability of concrete. RCA also affected the compressive strength, modulus of elasticity, and permeable voids of concrete. At the age of 28 days, the concrete with 100% RCA provided 12.2% lower compressive strength and 17.7% lesser modulus of elasticity than the control concrete. Also, 100% RCA increased the permeable voids of 28-day old concrete by 8.2%. However, no significant negative impact of RCA was observed on the flexural and splitting tensile strengths of concrete.

  18. Compressive Strength of Concrete Using Recycled Concrete Aggregate as Complete Replacement of Natural Aggregate

    Osei, Daniel Yaw

    2013-01-01

    This paper presents a report of an experimental investigation on the effect of complete replacement of natural aggregate by recycled concrete aggregate in the production of concrete on the compressive strength of concrete. Two sets of concrete mixtures of ratios 1:3:6, 1:2:4, 1:11/2:3, 1:1:2 by mass were cast using natural aggregates and recycled aggregates concrete respectively. The 28-day compressive strengths of 1:3:6, 1:2:4, 1:11/2:3, 1:1:2 concrete using recycled concrete aggregates were...

  19. HIGH TEMPERATURE PERFORMANCE OF SUSTAINABLE CONCRETE WITH RECYCLED CONCRETE AGGREGATES

    Gales, John; Parker, Thomas; Green, Mark F.; Cree, Duncan; Bisby, Luke

    2014-01-01

    The substitution of conventional aggregates in concrete with recycled concrete aggregates (RCA) can act to lower environmental impact. Applications of concrete with RCA are limited because of a lack of research providing clear design guidance. Specifically, the performance in fire must be considered. To address this need, three different concrete mixes were assessed for performance at high temperature with the only variable being the proportion of coarse aggregate substituted with RCA. For ea...

  20. Frost resistance of concrete with crushed brick as aggregate

    Janković Ksenija

    2010-01-01

    Full Text Available The investigation included concrete made by using recycled brick as aggregate. Experimental work included several types of concrete made with the same cement content (385 kg/m3, and same consistency (slump about 1 cm. Recycled brick and combination of natural river aggregate and recycled brick were used as aggregates. The influence of percentage and grain size of crushed brick aggregate on concrete compressive strength, water absorption and frost resistance were observed. On the basis of the results obtained during experimental research, a general conclusion can be drawn that the application of recycled concrete as aggregate can lead to new composites with satisfactory physical-mechanical properties.

  1. Studies on recycled aggregates-based concrete.

    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. PMID:16784165

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

    Hongying Dong; Wanlin Cao; Jianhui Bian; Jianwei Zhang

    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...

  3. Utilization Possibility of Natural Aggregate Resources in Central Town of Tokat as Concrete Aggregate

    S. I. Tutmaz

    2010-01-01

    Full Text Available In this study, aggregates of three quarries sampled from Tokat Province were tested to evaluate their suitability for concrete production. The aggregates were supplied from Yesilirmak River, and largely used in agricultural structures constructed in Tokat. Standard aggregate tests approved by Turkish Standards Institute were carried out to analyze the samples. Granulation, unit weight, specific weight, water absorption rate, resistance to frost, resistance against abrasion, ratio of fine materials, organic material contents and, mineralogical analysis of aggregates sampled from aggregate quarries were determined. Pressure resistance tests were conducted on concrete prepared by the aggregates. The results indicated that the aggregate granulation distribution of aggregate quarries evaluated was not suitable however other parameters determined were appropriate for concrete production. The resultant concrete had sufficient pressure resistance. The possible solutions to improve the improper characteristics of aggregates used in concrete were also determined and introduced with this study.

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

    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.

  5. Shrinkage of concrete with replacement of aggregate with recycled concrete aggregate

    Gómez Soberón, José Manuel Vicente

    2002-01-01

    In this paper we present the experimental analysis of samples of concrete where portion of the natural aggregate were replaced with recycled aggregate originating from concrete (RCA). Experimental analysis to obtain the shrinkage properties (basic and dried) of the concrete containing recycled concrete aggregate (CRCA) was performed. The percentages of replacement of natural aggregate with RCA were 0%, 15%, 30%, 60% and 100% with test conditions of 50% RH and 20°C. The results of these ...

  6. Mechanical Characteristic of Pervious Concrete Considering the Gradation and Size of Coarse Aggregates

    Alireza Joshaghani

    2014-09-01

    Full Text Available Pervious concrete is a kind of sustainable pavement with high permeability which is becoming more common as a storm water management. The purpose of this study was to investigate the effects of coarse aggregate on physical and mechanical properties of the pervious concrete such as density, strength, porosity and permeability at 7, 28, 56 days. This experimental investigation conducted by comparing nine different mixtures. Taguchi design of experiments used to optimize the performance of these characteristics. To test the influence of aggregate systematically, water to cement ratio (w/c, paste content and coarse aggregate size were kept constant at 3 levels. 9.5, 12.5 and 19.0 mm were used for maximum aggregate sizes. The relationship between strength and porosity for pervious concrete are found to be dependent on coarse aggregate size. The test results demonstrated when the maximum size of the coarse aggregate increased, the strength decreases and the permeability and porosity grows up. An increased aggregate amount resulted in a significant decrease in compressive strength due to the subsequent decrease in paste amount. Age and coarse aggregate size had effect on the pervious concrete characteristic. To meet the specification requirements in the mix design of pervious concrete, considering both compressive strength and permeability is necessary. Finally, a parametric study is conducted to investigate the influence of design factors on the properties of porous concrete. The general equations for pervious concrete are related to compressive strength and void ratio for different aggregate sizes.

  7. Some Properties of concretes containing recycled aggregates

    DJERBI TEGGUER, Assia; SAILLIO, Mickael; MAIH-NHU, Johnathan; SCHMITT, Lucie; ROUGEAU, Patrick

    2015-01-01

    This paper presents the results of an experimental campaign which aimed at determining the viability of incorporating recycled aggregates from concrete, in the production of a new concrete, with acceptable performances for its use in new structures. Nine concrete mixtures with different recycled aggregates contents and with different water to binder (w/b) ratio were studied. The mean compressive strength for the reference concretes is comprised between 30 and 60 MPa. Tests were performed to m...

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

    Han-Seung Lee

    2014-06-01

    Full Text Available 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.

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

    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. PMID:20176466

  10. Modeling compressive strength of recycled aggregate concrete by Artificial Neural Network, Model Tree and Non-linear Regression

    Neela Deshpande

    2014-12-01

    Full Text Available In the recent past Artificial Neural Networks (ANN have emerged out as a promising technique for predicting compressive strength of concrete. In the present study back propagation was used to predict the 28 day compressive strength of recycled aggregate concrete (RAC along with two other data driven techniques namely Model Tree (MT and Non-linear Regression (NLR. Recycled aggregate is the current need of the hour owing to its environmental friendly aspect of re-use of the construction waste. The study observed that, prediction of 28 day compressive strength of RAC was done better by ANN than NLR and MT. The input parameters were cubic meter proportions of Cement, Natural fine aggregate, Natural coarse Aggregates, recycled aggregates, Admixture and Water (also called as raw data. The study also concluded that ANN performs better when non-dimensional parameters like Sand–Aggregate ratio, Water–total materials ratio, Aggregate–Cement ratio, Water–Cement ratio and Replacement ratio of natural aggregates by recycled aggregates, were used as additional input parameters. Study of each network developed using raw data and each non dimensional parameter facilitated in studying the impact of each parameter on the performance of the models developed using ANN, MT and NLR as well as performance of the ANN models developed with limited number of inputs. The results indicate that ANN learn from the examples and grasp the fundamental domain rules governing strength of concrete.

  11. Performance of fly ash concretes containing lightweight EPS aggregates

    K. Ganesh Babu; D. Saradhi Babu [Indian Institute of Technology Madras, Chennai (India). Structures and Materials Laboratory, Department of Ocean Engineering

    2004-08-01

    Non-absorbent man-made aggregates like expanded polystyrene (EPS) do not suffer with the disadvantage of water absorption, which makes production of the normal lightweight aggregate concrete difficult. The present investigation is directed towards the development and performance evaluation of concrete composites containing EPS aggregates. Lightweight EPS concrete composites were produced by replacing the normal aggregate, either partially or fully, with EPS aggregates depending upon the density and strength required. The study covers the use of EPS beads as lightweight aggregate both in concrete and mortar, containing a fly ash replacement of 50% in the cementitious material. The concretes were designed to cover a wide range of densities (550-2200 kg/m{sup 3}), through EPS replacements ranging from 95% to 0%. The results were compared with similar concrete composites, essentially having OPC as the binder, from the literature. The study indicates that the EPS mixes produced with fly ash show lower absorption values compared to the mixes with OPC reported earlier. These concretes were also found to have a better chemical resistance. The chloride permeability of these concretes was seen to be 50-65% lower compared to that of normal concretes having similar water cement ratios. The corrosion rates of these concretes were also lower compared to the normal concretes.

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

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

    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 characteristi...

  13. Effect of Fractal Dimension of Fine Aggregates on the Concrete Chloride Resistance

    Xue, Wen; J. Chen

    2016-01-01

    The relationship between fractal dimension of fine aggregates and the chloride resistance of concrete was investigated in this study. Both concrete and mortar specimens were cast. Concrete specimens were in the same mix design as the mortar specimens except for the coarse aggregates. The specimens were divided into different groups based on the gradation of the fine aggregates. The chloride resistances of concrete specimens were tested by using the rapid chloride migration method. The results...

  14. The Influence of Crushed Concrete Demolition Waste Aggregates on the Hardening Process of Concrete Mixtures

    Olga FINOŽENOK; Ramunė ŽURAUSKIENĖ; Rimvydas ŽURAUSKAS

    2013-01-01

    Concrete – complex structure composite material consisting of the components with various structure and size. Not only coarse and fine aggregates are used in concrete production, but also filler aggregates. Aggregates of natural, man-made origin or aggregates, produced from recycled materials, can be utilised in concrete production. Aggregates can be produced from recycled materials by reprocessing of concrete and reinforced concrete waste. The influence of the filler aggregates produced from...

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

    Cheng-Chih Fan

    2015-05-01

    Full Text Available 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.

  16. Study of Recycled Concrete Aggregates

    Jitender Sharma; Sandeep Singla

    2014-01-01

    This paper describes the introduction and production of recycled concrete aggregates and its various applications in the construction industry. In this paper, properties of recycled aggregates and its comparison with the natural aggregates are also mentioned. Future recommendations about RCA are also included.

  17. Performance of Recycled Aggregate Concrete Containing Micronised Biomass Silica

    Suraya Hani Adnan; Ismail Abdul Rahman; Lee Yee Loon

    2011-01-01

    This paper presents a study on Micronised Biomass Silica (MBS) that was produced from the controlled burning of waste Rice Husk. The MBS was used as pozzolan material to enhance the performance of Recycled Aggregate Concrete (RAC). Various percentages by mass of Micronised Biomass Silica were applied in the normal and recycled aggregate concrete cube samples. Compressive strength and water permeability tested on the samples at the age of 7, 14, 28 and 90 days showed that concrete containing M...

  18. Utilisation of iron ore tailings as aggregates in concrete

    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.

  19. Influence of water absorption of coarse recycled concrete aggregates on the performance of concrete

    Joseph, Miquel

    2014-01-01

    The “ValReCon20 program” has proven the possibility to replace up to 100% of the coarse virgin aggregates by coarse recycled concrete aggregates (CRCA) in concrete of strength class C25/30. At this moment most uncertainties about recycled concrete concern durability in aggressive environments. This PHD researches destructive mechanisms that use water as transportation for harmful reagents. The physical phenomenon that describes water transportation is known as “Water Permeability” This is...

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

    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. PMID:25188783

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

    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.

  2. VERIFICATION OF 3-PHASES COMPOSITE MODEL FOR DRYING SHRINKAGE OF CONCRETE WITH DEFFERENT AGGREGATE PROPERTIES

    Tanaka, Kie; Shima, Hiroshi

    Properties of aggregate are not taken into account in current codes for drying shrinkage of concrete although the drying shrinkage is affected by the properties of aggregate. Aggregate restrains cement paste from shrinkage so that the drying shrinkage of concrete is controlled by drying shrinkage and Young's modulus of aggregate itself. The effect of the aggregate properties on drying shrinkage of concrete can be calculated by composite model in which concrete consists of cement paste and aggregate. Several different kind of coarse aggregate were used in order to verify a 3-phases composite model for drying shrinkage. Drying shrinkage and Young's modulus of cement paste, aggregate and concrete were measured. It was verified that drying shrinkage of concrete can be estimated accurately by the composite model associating with both drying shrinkage and Young's modulus of aggregate.

  3. Concrete manufacture with un-graded recycled aggregates

    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. 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 re...

  4. Effect of Chipped Rubber Aggregates on Performance of Concrete

    Sunil N. Shah

    2014-12-01

    Full Text Available Due to rapid growth in automobile industry, use of tyre increases day to day and there is no reuse of the same to decrease the environmental pollution. The decomposition and disposing of waste tyre rubber is harmful to environment. This research reflects the reuse of waste tyre rubber into concrete after observing their properties. In that experimental work chipped rubber aggregates replaced to the natural coarse aggregates by varying percentage of 3, 6, 9 and 12 with comparison of 0% replacement. Silica fume is replaced in 10% with cement for improving the bond properties between cement paste and rubber. In evaluation, test has been carried out to determine the properties of concrete such as workability, unit weight, flexural strength and split tensile strength. The workability of fresh concrete is observed with the help of compaction factor test. From the test of compaction factor, workability is decrease with increasing percentage of chipped rubber. The specific gravity of chipped rubber aggregates is lower as compared to natural aggregates therefore decrease the unit weight of rubber mix concrete. Increasing chipped rubber aggregates as partial replacement into concrete reduces compressive strength. So these can use in non-primary structural applications of medium to low strength requirements. The overall results of study show that it is possible to use recycled rubber tyre aggregates in concrete construction as partial replacement to natural coarse aggregates.

  5. Lightweight concrete with Algerian limestone dust. Part II: study on 50% and 100% replacement to normal aggregate at timely age

    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.

  6. Concrete Waste Recycling Process for High Quality Aggregate

    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

  7. Use of Recycled Aggregate and Fly Ash in Concrete Pavement

    Myle N. James

    2011-01-01

    Full Text Available Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55 the compressive strength, modulus of electricity and flexural strength for concrete with recycled aggregate and fly ash with 0, 25% replacing cement in mass were considered. Results: The material properties of recycled aggregate concrete with fly ash indicate comparable results with that of concrete with natural aggregate and without fly ash. Conclusion/Recommendations: The recycled materials could be used in concrete pavement and it will promote the sustainability of concrete.

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

    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)

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

    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. The successful application of PAC techniques utilized primarily in solving construction difficulties associated with confined and heavily congested regions of the PCRV is described. 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 pipes layout, grouting sequence, grout level monitoring, concrete temperature control, and pre-construction mockups are described. (U.S.)

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

    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. PMID:24316812

  11. Rio 2016 sustainable construction commitments lead to new developments in recycled aggregate concrete

    Toledo Filho, R.D.; Koenders, E.A.B.; Pepe, M.; Cordeiro, G.C.; Fairbairn, E.; Martinelli, E

    2013-01-01

    The Brazilian construction industry is committed to delivering the venues and infrastructure of the Rio 2016 Olympic and Paralympic Games with zero increase in carbon dioxide emissions, reduced consumption of raw materials, increased use of renewable materials and 100% local recycling of construction waste. This in turn has led to significant research and development into using cement replacements – particularly sugar-cane ash from local ethanol production – and recycled aggregates in concret...

  12. Durability of concrete mixed with fine recycled aggregates

    Salomon Levy; Paulo Helène

    2007-01-01

    In this paper, an analysis was conducted on the influence of the use of 20%, 50% and 100% contents of two types of fine recycled aggregates (from demolish concrete and from old masonry) on the following properties of concrete: water absorption by immersion, pore volume, carbonation and resistivity. This analysis was not restricted to compare mixtures from a table of results. All the analysis was based on concrete family behavior. The Mix Design Nomograms (MDN) was made fo...

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

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

    2016-01-01

    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...

  14. Investigation of the effect of aggregates' morphology on concrete creep properties by numerical simulations

    Prestress losses due to creep of concrete is a matter of interest for long-term operations of nuclear power plants containment buildings. Experimental studies by Granger (1995) have shown that concretes with similar formulations have different creep behaviors. The aim of this paper is to numerically investigate the effect of size distribution and shape of elastic inclusions on the long-term creep of concrete. Several microstructures with prescribed size distribution and spherical or polyhedral shape of inclusions are generated. By using the 3D numerical homogenization procedure for viscoelastic microstructures proposed by Šmilauer and Bažant (2010), it is shown that the size distribution and shape of inclusions have no measurable influence on the overall creep behavior. Moreover, a mean-field estimate provides close predictions. An Interfacial Transition Zone was introduced according to the model of Nadeau (2003). It is shown that this feature of concrete's microstructure can explain differences between creep behaviors

  15. Investigation of the effect of aggregates' morphology on concrete creep properties by numerical simulations

    Lavergne, F. [Université Paris-Est, Laboratoire Navier (ENPC, IFSTTAR, CNRS), 77455 Marne-la-Vallée Cedex (France); Sab, K., E-mail: karam.sab@enpc.fr [Université Paris-Est, Laboratoire Navier (ENPC, IFSTTAR, CNRS), 77455 Marne-la-Vallée Cedex (France); Sanahuja, J. [Département Mécanique des Matériaux et des Composants, EDF R& D, Site des Renardières, Avenue des Renardières, 77818 Moret-Sur-Loing Cedex (France); Bornert, M. [Université Paris-Est, Laboratoire Navier (ENPC, IFSTTAR, CNRS), 77455 Marne-la-Vallée Cedex (France); Toulemonde, C. [Département Mécanique des Matériaux et des Composants, EDF R& D, Site des Renardières, Avenue des Renardières, 77818 Moret-Sur-Loing Cedex (France)

    2015-05-15

    Prestress losses due to creep of concrete is a matter of interest for long-term operations of nuclear power plants containment buildings. Experimental studies by Granger (1995) have shown that concretes with similar formulations have different creep behaviors. The aim of this paper is to numerically investigate the effect of size distribution and shape of elastic inclusions on the long-term creep of concrete. Several microstructures with prescribed size distribution and spherical or polyhedral shape of inclusions are generated. By using the 3D numerical homogenization procedure for viscoelastic microstructures proposed by Šmilauer and Bažant (2010), it is shown that the size distribution and shape of inclusions have no measurable influence on the overall creep behavior. Moreover, a mean-field estimate provides close predictions. An Interfacial Transition Zone was introduced according to the model of Nadeau (2003). It is shown that this feature of concrete's microstructure can explain differences between creep behaviors.

  16. Frost resistance of concrete with crushed brick as aggregate

    Janković Ksenija; Bojović Dragan; Nikolić Dragan; Lončar Ljiljana; Romakov Zoran

    2010-01-01

    The investigation included concrete made by using recycled brick as aggregate. Experimental work included several types of concrete made with the same cement content (385 kg/m3), and same consistency (slump about 1 cm). Recycled brick and combination of natural river aggregate and recycled brick were used as aggregates. The influence of percentage and grain size of crushed brick aggregate on concrete compressive strength, water absorption and frost resistance were observed. On the basis of th...

  17. Experimental analysis of properties of high performance recycled aggregate concrete

    Gonzàlez Corominas, Andreu; Etxeberria Larrañaga, Miren

    2014-01-01

    Due to the increase in the demolition of high strength concrete structures and the interest of precast concrete companies in being more competitive, it is necessary to analyse the use of recycled concrete aggregates (RCA) in high performance concrete (HPC). In this study, HPC were produced using 20%, 50% and 100% of RCA on substitution of natural coarse aggregates. Three types of RCA were used, they were produced crushing original concrete of 100, 60 and 40 MPa of compressive strength. The ph...

  18. Use of Recycled Aggregate and Fly Ash in Concrete Pavement

    Myle N. James; Wonchang Choi; Taher Abu-Lebdeh

    2011-01-01

    Problem statement: Recycled materials aggregate from the demolished concrete structures and fly ash from burning coal shows the possible application as structural and non structural components in concrete structures. This research aims to evaluate the feasibility of using concrete containing recycled concrete aggregate and fly ash in concrete pavement. Approach: Two water cement ratio (0.45 and 0.55) the compressive strength, modulus of electricity and flexural streng...

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

    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.

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

    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. PMID:25243213

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

    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.

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

    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)

  3. Residue strength, water absorption and pore size distributions of recycled aggregate concrete after exposure to elevated temperatures

    Kou, Shi-Cong; Poon, Chi-Sun; Etxeberria Larrañaga, Miren

    2014-01-01

    In this paper, the effects of high temperature exposure of recycled aggregate concretes in terms of residual strengths, capillary water absorption capacity and pore size distribution are discussed. Two mineral admixtures, fly ash (FA) and ground granulated blast furnace (GGBS) were used in the experiment to partially replace ordinary Portland cement for concrete production. The water to cementitious materials ratio was maintained at 0.50 for all the concrete mixes. The replacement levels of n...

  4. Utilisation of iron ore tailings as aggregates in concrete

    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...

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

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

    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,...

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

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

    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...

  7. Feasibility of water seepage monitoring in concrete with embedded smart aggregates by P-wave travel time measurement

    Zou, Dujian; Liu, Tiejun; Huang, Yongchao; Zhang, Fuyao; Du, Chengcheng; Li, Bo

    2014-06-01

    Water seepage in concrete threatens the safety of marine constructions and reduces the durability of concrete structures. This note presents a smart aggregate-based monitoring method to monitor the travel time evolution of a harmonic stress wave during the water infiltrating process in concrete structures. An experimental investigation, in which two plain concrete columns were examined under different water infiltration cases, verified the validity of the proposed monitoring method. The test results show that the travel time of the harmonic stress wave is sensitive to the development of water seepage in concrete and decreases with increasing water seepage depth. The proposed active monitoring method provides an innovative approach to monitor water seepage in concrete structures.

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

    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. PMID:21775123

  9. Study Concerning Characterization of Some Recycled Concrete Aggregates

    Robu Ion; Mazilu Claudiu; Deju Radu

    2016-01-01

    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.

  10. Study Concerning Characterization of Some Recycled Concrete Aggregates

    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.

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

    Gideon Siringi; Ali Abolmaali; 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...

  12. Using of Local Limestone as Aggregate in Concrete Mixture

    Dr.Muyasser M. Jomaa'h

    2012-03-01

    Full Text Available This research deals with the field investigations and construction properties for using limestone as a lightweight course aggregate in concrete mixture in stead of normal coarse aggregate. Concrete cubes samples have been prepared with dimensions of 150*150*150 mm according to ASTM. For these samples the normal coarse aggregate was replaced by 100% coarse crushed limestone. Three types of limestone which were used (Al-Sinea, Makhool and Himreen, it was found that the Al-Sinea type of limestone gave a good combination (fcu =32.11MPa without admixtures. The obtained results showed a suitable reduction in dead loads of structural elements and cost. Accordingly, the usage of limestone will improve the structural applications and concrete mix properties to attain economic viability. These above results make limestone as a good alternative of normal coarse aggregate

  13. Basic Properties of Concrete Incorporating Recycled Ceramic Aggregate and Ultra-fine Sand

    LIU Fengli; LIU Junhua; MA Baoguo; HUANG Jian; LI Hainan

    2015-01-01

    Recycled ceramic mixed sand (RCMS) was obtained by partially replacing ultra-fine sand with recycled ceramic coarse sand (RCCS). The effects of RCCS replacement rate on the apparent density, workability, compressive strength and splitting tensile strength of recycled ceramic concrete (RCC) were investigated. In addition, the relationship between the water-cement ratio and compressive strength of RCC was also studied. The experimental results indicate that the reusing of recycled ceramic aggregate can improve the cohesiveness and water retentiveness of fresh concrete and benefit the mechanical properties development. When the RCCS replacement rate is not less than 40%, the mechanical properties of RCC are superior to those of the reference concrete. Moreover, when recycled ceramic medium sand was completely used as fine aggregate, the maximum increase in both compressive strength and splitting tensile strength were obtained, comparing with those of reference concrete, the increment ratio was 19.85% and 32.73%, respectively. The microscopic analysis shows that the using of recycled ceramic aggregate can meliorate distinctly the structure of the interfacial transition zone (ITZ) and increase the compaction degree of cement paste. Furthermore, an expression of the compressive strength of RCC and the cement-water ratio is regressed and gains a good linear relativity. It is an effective way to recycle waste ceramic, and the consumption of recycled ceramic aggregate could reach from 26.9%to 47.6%of the total weight of aggregate in producing concrete.

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

    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. Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali–silica reaction

    Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali–silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali–silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: ► ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). ► Cathodoluminescence was combined with various microscopic techniques and image analysis. ► ASR was attributed to aggregates. ► Source materials of aggregates were identified based on cathodoluminescence characteristics. ► Quartz comes from different volcanic, plutonic and metamorphic parent rocks.

  16. Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali-silica reaction

    Stastna, A., E-mail: astastna@gmail.com [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Sachlova, S.; Pertold, Z.; Prikryl, R. [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Leichmann, J. [Department of Geological Sciences, Faculty of Science, Masaryk University in Brno, Kotlarska 267/2, 611 37 Brno (Czech Republic)

    2012-03-15

    Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali-silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali-silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: Black-Right-Pointing-Pointer ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). Black-Right-Pointing-Pointer Cathodoluminescence was combined with various microscopic techniques and image analysis. Black-Right-Pointing-Pointer ASR was attributed to aggregates. Black-Right-Pointing-Pointer Source materials of aggregates were identified based on cathodoluminescence characteristics. Black-Right-Pointing-Pointer Quartz comes from different volcanic, plutonic and metamorphic parent rocks.

  17. Evaluation Of Flexure Strength Behavior Of Over Burnt Brick Ballast Aggregate Concrete

    Tariq Ali,

    2014-01-01

    Full Text Available Regional conditions enforced engineers to generate a study on concrete which incorporate Over Burnt Brick Ballast Aggregate partially due to their abundance. 5%, 10%, 15%, and 20% (M05, M10, M15, M20 incorporation was used as partial replacement of natural coarse aggregate in concrete. Analysis of incorporated concrete was done in fresh state as well in hardened state to evaluate different properties of concrete i.e. slump value, compaction factor value, unit weight, flexural strength and Los Angeles abrasion value. From experimental approach it is concluded that Concrete formed with over burnt brick ballast aggregate showed beneficial performance as compared with the concrete made up of natural aggregate obtained from Sargodha. It reduces the cost of concrete by reducing the aggregate cost and produces economical infrastructure system. The waste generated from the brick kiln is utilized efficiently, making environment friendly encouraging green construction.

  18. Strength Development and Water Permeability of Engineered Biomass Aggregate Pervious Concrete

    Shahidan S.; Koh H. B.; Sharif Alansi A. M.; Loon L. Y.

    2016-01-01

    Pervious concrete has a high rate of permeability, low strength and high porosity. It is commonly used in the area of storm water management. However, its use has been limited to pavements with low volume traffic. Pervious concrete is different from normal concrete as the mixture contains no fine aggregates. The aggregate is usually of a single size bonded by a cement paste. This study focuses mainly on the effect of Engineered Biomass Aggregate (EBA) on the compressive strength and permeabil...

  19. The impact of different lightweight aggregates on properties of high strength concrete

    Šubic, Nika

    2014-01-01

    High strength concrete is known for its many favorable qualities. However it also has some negative characteristics like autogenous shrinkage which can be reduced by adding saturated lightweight aggregate to the concrete mix. The effect of using different types of lightweight aggregate on compressive strength and shrinkage of concrete is discussed in this graduation thesis. Factors influencing the success of internal curing with prewetted lightweight aggregate are described in theoretic...

  20. Physio-chemical reactions in recycle aggregate concrete.

    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. PMID:18718710

  1. Some mechanical properties of normal and recycled aggregate concretes

    Kazemi, K Akhavan; EREN, Özgür; Rezaei, Alireza

    2015-01-01

    This paper describes an experimental study conducted to investigate the properties of concretes produced with recycled aggregates and normal aggregates for two different concrete classes (C20/25, C30/37). Tests of compressive strength, splitting tensile strength, ultrasonic pulse velocity, rebound hammer, wet and dry density, and freeze-thaw resistance were conducted on specimens of the concretes. Moreover, slump test was conducted on fresh concrete. The results showed that the slump of Recyc...

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

    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. PMID:19398196

  3. Design development of aggregates cooling systems for hot weather concreting

    Ahmed, Khaled I. E.; A.M.S. HAMOUDA; Gadala, M.S.

    2015-01-01

    Using hot aggregates, in concrete production, results in a drop in compressive strength of the produced concrete. Various methods have been proposed for cooling concrete aggregates. This paper proposes new two designs for aggregates cooling systems for various production rate demands. Conveyor system for small to moderate production rates and rotating drum for high production rates. Simulation of the heat flow during the cooling process over the conveyor and through the drum are analyzed with...

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

    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)

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

    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.

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

    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. PMID:24889792

  7. High Modulus Asphalt Concrete with Dolomite Aggregates

    Haritonovs, V.; Tihonovs, J.; Smirnovs, J.

    2015-11-01

    Dolomite is one of the most widely available sedimentary rocks in the territory of Latvia. Dolomite quarries contain about 1,000 million tons of this material. However, according to Latvian Road Specifications, this dolomite cannot be used for average and high intensity roads because of its low quality, mainly, its LA index (The Los Angeles abrasion test). Therefore, mostly the imported magmatic rocks (granite, diabase, gabbro, basalt) or imported dolomite are used, which makes asphalt expensive. However, practical experience shows that even with these high quality materials roads exhibit rutting, fatigue, and thermal cracks. The aim of the research is to develop a high performance asphalt concrete for base and binder courses using only locally available aggregates. In order to achieve resistance against deformations at a high ambient temperature, a hard grade binder was used. Workability, fatigue and thermal cracking resistance, as well as sufficient water resistance is achieved by low porosity (3-5%) and higher binder content compared to traditional asphalt mixtures. The design of the asphalt includes a combination of empirical and performance based tests, which in laboratory circumstances allow simulating traffic and environmental loads. High performance AC 16 base asphalt concrete was created using local dolomite aggregate with polymer modified (PMB 10/40-65) and hard grade (B20/30) bitumen. The mixtures were specified based on fundamental properties in accordance with EN 13108-1 standard.

  8. A Study of Concrete Made with Fine and Coarse Aggregates Recycled from Fresh Concrete Waste

    Mamery Sérifou; Sbartaï, Z. M.; S. Yotte; Boffoué, M. O.; Emeruwa, E.; Bos, F

    2013-01-01

    This paper deals with the possibility of using fresh concrete waste as recycled aggregates in concrete. An experimental program based on two variables (proportion of fine aggregates replacement and proportion of coarse aggregates replacement) was implemented. The proportions of replacement were 0%, 50%, and 100% by mass of aggregates. Several mechanical properties were tested as compressive and tensile strengths. The results show a good correlation between aggregates replacement percentage an...

  9. Performance of Recycled Aggregate Concrete Containing Micronised Biomass Silica

    Suraya Hani Adnan

    2011-07-01

    Full Text Available This paper presents a study on Micronised Biomass Silica (MBS that was produced from the controlled burning of waste Rice Husk. The MBS was used as pozzolan material to enhance the performance of Recycled Aggregate Concrete (RAC. Various percentages by mass of Micronised Biomass Silica were applied in the normal and recycled aggregate concrete cube samples. Compressive strength and water permeability tested on the samples at the age of 7, 14, 28 and 90 days showed that concrete containing MBS has attained higher compressive strength. Furthermore, the test on MBS also showed its ability to enhance the concrete water permeability. Lengthen to this; the study established a good correlation between the MBS content with compressive strength and water permeability coefficient.

  10. Strength Development and Water Permeability of Engineered Biomass Aggregate Pervious Concrete

    Shahidan S.

    2016-01-01

    Full Text Available Pervious concrete has a high rate of permeability, low strength and high porosity. It is commonly used in the area of storm water management. However, its use has been limited to pavements with low volume traffic. Pervious concrete is different from normal concrete as the mixture contains no fine aggregates. The aggregate is usually of a single size bonded by a cement paste. This study focuses mainly on the effect of Engineered Biomass Aggregate (EBA on the compressive strength and permeability of previous concrete. Three types of mixtures with 0% natural aggregate (NA, 5% BA and 5% of EBA have been studied in this research. A total of 27 150 mm cubes were casted in the laboratory for compressive strength and permeability test. This research aims to enhance the understanding of engineered biomass aggregate pervious concrete as well as the use of pervious concrete for sustainable construction activities due to the environmental benefits it offers.

  11. Utilization of Recycled Concrete Aggregates in Stone Mastic Asphalt Mixtures

    Mohammad Saeed Pourtahmasb; Mohamed Rehan Karim

    2014-01-01

    Recycled concrete aggregate (RCA) is considered as one of the largest wastes in the entire world which is produced by demolishing concrete structures such as buildings, bridges, and dams. It is the intention of scientists and researchers, as well as people in authority, to explore waste material recycling for environmental and economic advantages. The current paper presents an experimental research on the feasibility of reusing RCA in stone mastic asphalt (SMA) mixtures as a partial replaceme...

  12. Effects of maximum aggregate size on UPV of brick aggregate concrete.

    Mohammed, Tarek Uddin; Mahmood, Aziz Hasan

    2016-07-01

    Investigation was carried out to study the effects of maximum aggregate size (MAS) (12.5mm, 19.0mm, 25.0mm, 37.5mm, and 50.0mm) on ultrasonic pulse velocity (UPV) of concrete. For investigation, first class bricks were collected and broken to make coarse aggregate. The aggregates were tested for specific gravity, absorption capacity, unit weight, and abrasion resistance. Cylindrical concrete specimens were made with different sand to aggregate volume ratio (s/a) (0.40 and 0.45), W/C ratio (0.45, 0.50, and 0.55), and cement content (375kg/m(3) and 400kg/m(3)). The specimens were tested for compressive strength and Young's modulus. UPV through wet specimen was measured using Portable Ultrasonic Non-destructive Digital Indicating Tester (PUNDIT). Results indicate that the pulse velocity through concrete increases with an increase in MAS. Relationships between UPV and compressive strength; and UPV and Young's modulus of concrete are proposed for different maximum sizes of brick aggregate. PMID:27085110

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

    Hongying Dong

    2014-12-01

    Full Text Available 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.

  14. The Influence of Crushed Concrete Demolition Waste Aggregates on the Hardening Process of Concrete Mixtures

    Olga FINOŽENOK

    2013-03-01

    Full Text Available Concrete – complex structure composite material consisting of the components with various structure and size. Not only coarse and fine aggregates are used in concrete production, but also filler aggregates. Aggregates of natural, man-made origin or aggregates, produced from recycled materials, can be utilised in concrete production. Aggregates can be produced from recycled materials by reprocessing of concrete and reinforced concrete waste. The influence of the filler aggregates produced from the crushed concrete waste on the characteristics of binder’s paste, when part of the binder (5; 10; 15; 20; 25; 30 % is replaced by such filler aggregate, is analysed in the research. Concrete mixtures with natural aggregates and crushed concrete waste were selected and concrete mixtures of required consistence were produced during the research. Exothermic reactions take place during the hardening of concrete mixture, at that time the heat is dissipated, which increases the temperature of the concrete sample. Thus the exothermic processes were investigated during the concrete’s mixture hardening period and the temperatures of exothermic reactions were determined.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3833

  15. A Study of Concrete Made with Fine and Coarse Aggregates Recycled from Fresh Concrete Waste

    Mamery Sérifou

    2013-01-01

    Full Text Available This paper deals with the possibility of using fresh concrete waste as recycled aggregates in concrete. An experimental program based on two variables (proportion of fine aggregates replacement and proportion of coarse aggregates replacement was implemented. The proportions of replacement were 0%, 50%, and 100% by mass of aggregates. Several mechanical properties were tested as compressive and tensile strengths. The results show a good correlation between aggregates replacement percentage and concrete properties. Concerning mechanical properties, a gradual decrease in compressive, splitting, and flexural strengthn with the increase in recycled aggregate percentage is shown.

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

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

    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 ...

  17. Mechanical and Durability Properties of Recycled Concrete Aggregate for Normal Strength Structural Concrete

    Suvash Chandra Paul

    2013-07-01

    Full Text Available The purpose of this study was to determine the suitability of using Recycled Concrete Aggregate (RCA in structural concrete based on a better understanding of its strength, stiffness and durability. RCA was collected from three different sources: a local landfill site, a local aggregate supplier and from the demolition of two old cooling towers in Cape Town, South Africa (RSA. All RCA was prepared by crushing the demolished concrete in a laboratory crusher at University of Stellenbosch. Their physical properties were determined for comparison of different sources of RCA. RCA replacement percentages of 0%, 30% and 100% to partially replace natural aggregate (NA in concrete were tested at different ages. Cube strength classes 30-40 MPa concrete were made to investigate the mechanical properties of RCA. Creep, shrinkage and durability properties were also tested for concrete with 0% and 30% RCA replacement of NA. It was found that RCA replacement by 30% (RCA30% of NA does not lead to any significant difference in strength and stiffness compared to concrete containing 100% NA in concrete. RCA100% replacement does show reduced strength and stiffness, but this is not significant and can be compensated for in standard ways. Durability index tests indicated similar durability performance of concrete with reasonable quality RCA30% compared with NA100%. Increased creep was however observed for RCA30% which must be considered in structural design. Little information is available about both the mechanical and durability properties of local RCA in RSA, where this research has been performed. The authors believe this report will assist to increase the confidence of engineers to consider using RCA in structural concrete in RSA as well as abroad.

  18. Improvement of the durability of concrete with recycled aggregates in chloride exposed environment

    Vázquez Ramonich, Enric; Barra Bizinotto, Marilda; Aponte Hernández, Diego Fernando; Jiménez Fernández, Cristian Gonzalo; Valls del Barrio, Susanna

    2014-01-01

    Recycled aggregates concrete (RAC) becomes an important participant in recycled materials, although there are still questionable issues about some of its properties. Durability of RAC and its relationship with recycled concrete aggregate (RCA) is often discussed, especially in relation with chloride penetration and diffusion properties. An extensive experimental campaign was performed in order to evaluate the effect of RCA content in the retention and diffusion of chlorides in RAC. The influe...

  19. Durability Indicators in High Absorption Recycled Aggregate Concrete

    Jiménez, Luis F.; Moreno, Eric I.

    2015-01-01

    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 ab...

  20. The Utility Of All -In-Aggregates For Concrete Production In Ghana

    Woode, Anthony; Amoah, David; Ashie, Prince Nikoi; Ollenu, Isaac Ashitei

    2014-01-01

    A study was conducted to establish the suitability of using all-in-aggregates as an alternative to conventional stones and sand for concrete production in order to reduce the cost of producing concrete for low cost housing without compromising on quality and strength. The physical and mechanical properties of all-in-aggregates obtained from ten different sites in three regions of Ghana and used for concrete production were therefore determined by carrying out various tests includ...

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

    MAJID MATOUQ ASSAS

    2016-01-01

    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 a...

  2. Experimental investigations on mode II fracture of concrete with crushed granite stone fine aggregate replacing sand

    Kanchi Balaji Rao; Vijaya Bhaskar Desai; D. Jagan Mohan

    2012-01-01

    With a view to implement sustainability concepts (namely, use of locally available materials and industrial by-products) in the concrete construction industry, the possibility of use of crushed stone fine aggregate as replacement to river sand is explored in this paper. Towards this, tests have been carried out on concrete cubes and concrete cylinders. The effect of variation in percentage replacement of river sand with crushed stone fine aggregate on the mechanical properties is studied. In ...

  3. Performance of Bridge Decks and Girders with Lightweight Aggregate Concrete

    Ramirez, J.A.; Olek, J.; Rolle, Eric Joseph; Manlone, Brian J.

    2000-01-01

    Structural lightweight concrete is a very versatile material and Haydite and Minergy lightweight aggregates can be utilized in the mixture development of concrete for use in girders and decks in bridges. More widespread use of lightweight aggregates (LWA) would result in savings in construction cost due to considerable dead load reduction. The materials phase of this research study evaluated the fresh concrete properties (slump, unit weight, and air content), the mechanical properties of ha...

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

    Sikiru ORITOLA; Abd. Latif SALEH; Abdul Rahman MOHD SAM

    2014-01-01

    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 produce...

  5. Effect of Aggregate Gradation with Fuller Distribution on Properties of Sulphoaluminate Cement Concrete

    GONG Chenchen; ZHANG Jie; WANG Shoude; LU Lingchao

    2015-01-01

    Experimental investigations on mechanical property and durability of sulphoaluminate cement concrete with aggregate gradations according to Fuller distribution are presented in this paper. Compressive strength, water impermeability and resistance capability to sulfate attack of SACC have the same trend of concrete with fine aggregates of Fuller distribution gradation<concrete with coarse aggregates of Fuller distribution gradation<concrete with total aggregates of Fuller distribution gradation. The relationship between bulk density of aggregate and water penetration depth obeyed the second-order polynomialy=0.002x2-6.863 8x+5 862.3, and had a notable correlationR2=0.979 9. The sulphoaluminate cement concrete with total aggregate gradation with Fuller distribution forh=0.50 had the best resistance capability to sulfate attack. It was a second-order polynomial relationship between bulk density of aggregates and water penetration depth of y=0.002x2-6.863 8x+5 862.3 withR2=0.979 9, which indicated notable correlation. The iftting formula between bulk density of aggregates and sulfate resistance coefifcient of SACC wasy=0.000 5x+0.370 4 withR2=0.958 5.

  6. Performance of Recycled Asphalt Pavement as Coarse Aggregate in Concrete

    Fidelis O. OKAFOR

    2010-12-01

    Full Text Available Recycled asphalt pavement (RAP is the reclaimed and reprocessed pavement material containing asphalt and aggregate. Most RAP is recycled back into pavements, and as a result there is a general lack of data pertaining to the mechanical properties for RAP in other possible applications such as Portland cement concrete. In the present study, some mechanical properties of Portland cement concrete containing RAP as coarse aggregate were investigated in the laboratory. Six concrete mixes of widely differing water/cement ratios and mix proportions were made using RAP as coarse aggregate. The properties tested include the physical properties of the RAP aggregate, the compressive and flexural strengths of the concrete. These properties were compared with those of similar concretes made with natural gravel aggregate. Results of the tests suggest that the strength of concrete made from RAP is dependent on the bond strength of the “asphalt-mortar” (asphalt binder-sand-filler matrix coatings on the aggregates and may not produce concrete with compressive strength above 25 MPa. However, for middle and low strength concrete, the material was found to compare favorably with natural gravel aggregate.

  7. Fracture and aggregate interlock mechanisms in reinforced concrete

    Nine tests regarding thin-webbed I-beams failing in shear because of stirrup yielding and concrete crushing are considered here. An incremental-iterative procedure for the nonlinear F.E. analysis of reinforced concrete structures is applied to three of the above beams. Solid concrete is modeled as a hypoelastic material, while cracked concrete (including fracture and aggregate interlock) is modeled with crack bands, according to the smeared crack approach

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

    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

  9. Acid Resistance of Concrete Containing Laterite Aggregate as Partial Coarse Aggregate Replacement

    K. Muthusamy

    2014-05-01

    Full Text Available In Malaysia, issues of granite aggregate depletion in future due to increasing use in concrete industry and the availability of laterite aggregate locally has initiated studies on concrete produced using laterite aggregate as partial coarse aggregate replacement. Although, replacement of laterite aggregate up to 30% able to produce concrete with the targeted strength but durability of this concrete towards acid attack yet to be investigated. Thus, this study presents and discusses the performance of concrete consisting various percentage of laterite aggregate integrated as partial coarse aggregate replacement upon exposure to acidic environment. Mixes consisting various content of laterite aggregate as partial coarse aggregate replacement ranging from 0, 10, 20, 30, 40 and 50%, respectively were prepared in form of cubes and then subjected to water curing for 28 days before immersed in hydrochloric acid solution for 1800 h. Performance of the specimens were observed through mass loss and strength reduction. Generally, durability performance of concrete produced using up to 20% of laterite aggregate is comparable to plain concrete.

  10. Investigation of the Usability of Travertine Quarry Wastes As Concrete Aggregate

    İbrahim Çobanoğlu

    2014-03-01

    Full Text Available Denizli basin is one of the most important travertine deposition area around the world. Kaklık, Kocabaş, Honaz, Aşağıdağdere, Akköy, Çivril are major production areas. Tectonic activity in the region has been negatively affected the block production efficiency in the quarries. Quarry wastes by wire cutting are collected in waste disposal areas and these materials do not use for any other purposes. In this study, investigation of usability of different sized travertine quarry wastes in concrete as aggregate is aimed. For this purpose, physico mechanical properties of aggregates were investigated and concrete mixtures were prepared. Strength of 7, 28 and 56 days concrete samples which are targeted of C30 concrete class were also determined. Strength of prepared travertine aggregated concrete compared to still being produced concrete. For comparison, all procedures were performed for limestone aggregated concrete. Thin sections were prepared for investigations of distribution and coupling of grains in cement material under polarizan microscope. 32.80-42.70 MPa and 39.34-46.04 MPa strengths were determined for travertine aggregated and limestone aggregated concretes respectively. By using travertine aggregate, limit values for C30 concrete class have been reached. This study demonstrates that the travertine quarry wastes can be used as aggregates in concrete. In Denizli region there is no concrete firm use travertine wastes as aggregate. It is thought that, as an alternative building material travertine can be used in production of brick, curbs, keystone and various materials. For this aim more detailed experimental studies on travertines are needed.

  11. RE-USE OF WASTE TIRES RUBBER AS FINE AGGREGATE REPLACEMENT IN CONCRETE MIX APPLICATIONS

    Falak O. Abas; Enass A. Abdul Ghafoor; Mohammed U.Abass

    2015-01-01

    Discarded waste tires are one of the important parts of solid waste which had historically been disposed of in to landfills also causing a serious environmental problem. Then this study explores the possibility of reusing discarded waste tires in concrete engineering applications through enhancing the properties of concrete mix as partial replacement with fine aggregate to produce ideal concrete mix. The percent of discarded waste tires substituted in to the concrete mix by weight...

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

    Francisco Cartuxo

    2016-02-01

    Full Text Available 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.

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

    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.

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

    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. PMID:20434898

  15. Properties of Recycled Aggregate Concrete Reinforced with Polypropylene Fibre

    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.

  16. Quality characteristics of fine aggregates and controlling their effects on concrete

    Järvenpää, Hanna

    2001-01-01

    For the aggregate producer, the concrete aggregates are end products, while, for the concrete manufacturer, the aggregates are raw materials to be used for mix designs and successful concrete production. The aim of this study was to identify which fine aggregate characteristics are important, and additionally to relate the extent of the effect that the aggregate has on the concrete as compared against the effect of the changes in mix design. The testing programme contained six different m...

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

    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.

  18. Lithuanian Quarry Aggregates Concrete Effects of Alkaline Corrosion Tests

    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%.

  19. Laboratory-scale sodium-carbonate aggregate concrete interactions

    A series of laboratory-scale experiments was made at 6000C 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+-300C for limestone and dolostone aggregates as well as for hydrated limestone concrete, and at 540+-100C for dehydrated limestone concrete, but were ill-defined for dolostone concrete. Major reaction products included CaO, MgO, Na2CO3, Na2O, 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

  20. Porosity of the recycled concrete with substitution of recycled concrete aggregate. An experimental study

    Gómez Soberón, José Manuel Vicente

    2002-01-01

    In this paper, we present the experimental analysis of samples of recycled concrete (RC) with replacement of natural aggregate (NA) by recycled aggregate originating from concrete (RCA). The results of the tests of mechanical properties of RC were used for comparison with tests of mercury intrusion porosimetry (MIP), in which the distribution of the theoretical pore radius, critical pore ratio, the surface area of the concrete, threshold ratio and average pore radius were studied at ages of 7...

  1. Concrete density estimation by rebound hammer method

    Ismail, Mohamad Pauzi bin, E-mail: pauzi@nm.gov.my; Masenwat, Noor Azreen bin; Sani, Suhairy bin; Mohd, Shukri [NDT Group, Nuclear Malaysia, Bangi, Kajang, Selangor (Malaysia); Jefri, Muhamad Hafizie Bin; Abdullah, Mahadzir Bin [Material Technology Program, Faculty of Applied Sciences, UiTM, Shah Alam, Selangor (Malaysia); Isa, Nasharuddin bin; Mahmud, Mohamad Haniza bin [Pusat Penyelidikan Mineral, Jabatan Mineral dan Geosains, Ipoh, Perak (Malaysia)

    2016-01-22

    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.

  2. Concrete density estimation by rebound hammer method

    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

  3. Exploratory Study of Palm Oil Fuel Ash as Partial Cement Replacement in Oil Palm Shell Lightweight Aggregate Concrete

    K. Muthusamy; Z. Nur Azzimah

    2014-01-01

    In Malaysia, issue of environmental pollution resulting from disposal of Palm Oil Fuel Ash (POFA) which is a by-product from palm oil mill has initiated research to incorporate this waste in Oil Palm Shell (OPS) lightweight aggregate concrete production. The current study investigates the effect of palm oil fuel ash content as partial cement replacement towards compressive strength OPS lightweight aggregate concrete. Several OPS lightweight aggregate concrete mixes were produced by replacing ...

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

    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.

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

    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

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

    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

  7. Equivalent Mortar Volume (EMV method for proportioning recycled aggregate concrete: Validation under the Spanish context and its adaptation to Bolomey methodology for concrete proportioning

    Jiménez, C.

    2013-09-01

    Full Text Available A new method for proportioning recycled aggregates concrete (RAC is used to check its feasibility under the Spanish context. First, an extensive experimental campaign has been done, with the purpose of check and analyze the applicability of the EMV method with two Spanish recycled concrete aggregates (RCA. The aim of the second part of the investigation, was to elaborate an adaptation of the EMV method to Bolomey methodology (1, using a 20% weight replacement of coarse natural aggregates (NA for RCA, and so, with this, comply with the Spanish Instruction for Structural Concrete (EHE 2008. Slump, air content, fresh and hardened densities, compressive strength and modulus of elasticity were determined and analyzed, in order to check the concrete properties. Finally, it was observed that, the EMV method is viable, and its adaptation, results in concrete mixes with similar or better properties than the natural aggregate concrete and RAC conventionally prepared.El nuevo método para el diseño de hormigón con árido reciclado (HAR es usado para comprobar su posibilidad de uso bajo el contexto español. Primeramente, se realiza una extensa campaña experimental, para analizar las posibilidades de su aplicación, usando dos áridos reciclados de hormigón (ARH españoles. En la segunda etapa se elabora una adaptación del método a la metodología propuesta por Bolomey (1, con 20% de reemplazo en peso de árido grueso natural (AN por ARH, para así cumplir con las recomendaciones estipuladas en la Instrucción de Hormigón Estructural (EHE 2008. Para determinar y analizar las propiedades del hormigón, se llevaron a cabo ensayos de asentamiento, contenido de aire, densidades, módulo elástico y resistencias a compresión. Finalmente, se concluye que el uso del nuevo método es viable, y que su adaptación produce hormigones con similares o mejores características que los elaborados para hormigón con árido convencional (HAC y HAR convencionales.

  8. Sulfate attack and reinforcement corrosion in concrete with recycled concrete aggregates and supplementary cementing materials

    Corral Higuera, Ramón; Arredondo Rea, Susana Paola; Neri Flores, M.A.; Gómez Soberón, José Manuel Vicente; Almeraya Calderón, F.; Castorena González, J.H.; Almaral Sánchez, Jorge Luis

    2011-01-01

    As strategies to contribute to the concrete industry sustainability, reinforced concrete was fabricated using recycled concrete coarse aggregate and replacing partially portland cement with supplementary cementing materials as fly ash and silica fume. On test specimens, partially immersed in 3.5% Na2SO4 aqueous solution, the effect of the recycled and supplementary materials against sulfate attack and reinforcement corrosion was evaluated. For such aim, weight loss of concrete and corrosion p...

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

    Yuanchen Guo; Jueshi Qian; Xue Wang; Zhengyi Yan; Huadong Zhong

    2015-01-01

    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 aggr...

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

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

    2014-01-01

    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 ...

  11. Theoretical Analysis on Mechanical Behavior of Axially Loaded Recycled Aggregate Concrete Filled Steel Tubes

    Yijie Huang

    2015-01-01

    Full Text Available A new mechanical model for analysing the behaviour of axially loaded recycled aggregate concrete filled steel tubes (RACFSTs stub columns is presented in this study. The model is derived from the typical elastoplasticity, the nonlinear elastic mechanics, and the properties of materials. Based on the mechanical model, a novel numerical program is developed. The mechanical model and the numerical program are adopted to study the effect of recycled coarse aggregate (RCA replacement percentage on RACFST mechanical behaviour. The complete load-deformation relationship of specimens, the steel tube axial and circumferential stresses, and the performance of the confined core concrete and the variation of interaction are also investigated. The analytical results indicate that this model is able to capture the mechanical behaviour of RACFST. It is also found that the axial and circumferential stresses of steel tube change nonlinearly during the loading stages. It is concluded that the behaviour of the confined core concrete is significantly influenced by the confining pressure. The steel tube confinement could improve the mechanical behaviour of RAC effectively and the RCA replacement percentage slightly changes the response of core concrete. Finally, the relations between confined core concrete and confining pressure are analysed.

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

    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.

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

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

    2014-12-01

    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.

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

    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)

  15. The Value Compressive Strength and Split Tensile Strength on Concrete Mixture With Expanded Polystyrene Coated by Surfactant Span 80 as a Partial Substitution of Fine Aggregate

    Hidayat, Irpan; Siauwantara, Alice

    2014-03-01

    The value of the density normal concrete which ranges between 2200-2400 kg/m3. Therefore the use of Expanded Polystyrene (EPS) as a subitute to fine aggregate can reduce the density of concrete. The purpose this research is to reduce the density of normal concrete but increase compressive strength of EPS concrete, with use surfactant as coating for the EPS. Variables of substitution percentage of EPS and EPS coated by surfactant are 5%,10%,15%,20%,25%. Method of concrete mix design based on SNI 03-2834-2000 "Tata Cara Pembuatan Rencana Campuran Beton Normal (Provisions for Proportioning Normal Concrete Mixture)". The result of testing, every increase percentage of EPS substitution will decrease the compressive strength around 1,74 MPa and decrease density 34,03 kg/m3. Using Surfactant as coating of EPS , compressive strength increase from the EPS's compressive strength. Average of increasing compressive strength 0,19 MPa and increase the density 20,03 kg/m3,average decrease of the tensile split strength EPS coated surfaktan is 0,84 MPa.

  16. The Value Compressive Strength and Split Tensile Strength on Concrete Mixture With Expanded Polystyrene Coated by Surfactant Span 80 as a Partial Substitution of Fine Aggregate

    Hidayat Irpan

    2014-03-01

    Full Text Available The value of the density normal concrete which ranges between 2200–2400 kg/m3. Therefore the use of Expanded Polystyrene (EPS as a subitute to fine aggregate can reduce the density of concrete. The purpose this research is to reduce the density of normal concrete but increase compressive strength of EPS concrete, with use surfactant as coating for the EPS. Variables of substitution percentage of EPS and EPS coated by surfactant are 5%,10%,15%,20%,25%. Method of concrete mix design based on SNI 03-2834-2000 “Tata Cara Pembuatan Rencana Campuran Beton Normal (Provisions for Proportioning Normal Concrete Mixture”. The result of testing, every increase percentage of EPS substitution will decrease the compressive strength around 1,74 MPa and decrease density 34,03 kg/m3. Using Surfactant as coating of EPS , compressive strength increase from the EPS’s compressive strength. Average of increasing compressive strength 0,19 MPa and increase the density 20,03 kg/m3,average decrease of the tensile split strength EPS coated surfaktan is 0,84 MPa.

  17. The Testing Strength Curves of Lightweight Aggregate Concrete by Rebound Method and Ultrasonic-rebound Combined Method

    RONG Hui; QIAN Chunxiang; GAO Lixiong; HAN Jiande; WANG Caihui

    2011-01-01

    The strength curves of lightweight aggregate concrete (LWAC) were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LCI5-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.

  18. INVESTIGATION OF THE USABILITY OF PYROPHYLLITE ROCK AS CONCRETE AGGREGATE

    ESEN, Yüksel; ÖZKAYA, Harun

    2011-01-01

    ABSTRACT The aim of the present study was to investigate the usability of Pyrophyllite rock, which was provided from Poturge district of Malatya province in eastern Turkey, as concrete aggregate. For this purpose some of the aggregate and hardened concrete tests were carried out. In the evaluation of the aggregate trial results; the aggregate loss of 28%, specific gravity of 2.67, saturated surface dry weight of 2.70, absorption percentage of 0.9 and the average loss percentage of 22% accord...

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

    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.

  20. Acoustic emission monitoring of recycled aggregate concrete under bending

    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.

  1. Structural Concrete Using Oil Palm Shell (OPS) as Lightweight Aggregate

    TEO, D. C. L.; M. A. Mannan; V.J. Kurian

    2006-01-01

    This paper presents part of the experimental results of an on-going research project to produce structural lightweight concrete using solid waste, oil palm shell (OPS), as a coarse aggregate. Reported in the paper are the compressive strength, bond strength, modulus of elasticity, and flexural behaviour of OPS concrete. It was found that although OPS concrete has a low modulus of elasticity, full-scale beam tests revealed that deflection under the design service loads is acceptable a...

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

    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.

  3. Application of Image Analysis to Identify Quartz Grains in Heavy Aggregates Susceptible to ASR in Radiation Shielding Concrete

    Daria Jóźwiak-Niedźwiedzka

    2016-03-01

    Full Text Available Alkali-silica reaction (ASR is considered as a potential aging-related degradation phenomenon that might impair the durability of concrete in nuclear containments. The objective of this paper is the application of digital analysis of microscopic images to identify the content and size of quartz grains in heavy mineral aggregates. The range of investigation covered magnetite and hematite aggregates, known as good absorbers of gamma radiation. Image acquisition was performed using thin sections observed in transmitted cross-polarized light with λ plate. Image processing, consisting of identification of ferrum oxide and epoxy resin, and the subsequent application of a set of filtering operations resulted in an adequate image reduction allowing the grain size analysis. Quartz grains were classified according to their mean diameter so as to identify the reactive range. Accelerated mortar bar tests were performed to evaluate the ASR potential of the aggregates. The SiO2 content in the heavyweight aggregates determined using the image analysis of thin sections was similar to XRF test result. The content of reactive quartz hematite was 2.7%, suggesting that it would be prone to ASR. The expansion test, according to ASTM C1260, confirmed the prediction obtained using the digital image analysis.

  4. Study on Behaviour of Concrete Mix Replaceing Fine Aggregate With Steel Slag At Different Properties

    P. Sateesh Kumar; VVS. Sarma

    2015-01-01

    This paper aims to study experimentally, the effect of partial replacement of fine aggregate by steel slag (ss), on the various strength and durability properties of concrete by using the mix designs .the optimum percentage of replacement of fine aggregate by steel slag is found. Workability of concrete gradually decreases, as the percentage of replacement increases which is found using slump test. Compressive strength, tensile strength, flexural strength and durability tests such...

  5. Influence of Mineral Admixtures on the Permeability of Lightweight Aggregate Concrete

    WANG Fazhou; HU Shuguang; DING Qingjun; PENG yanzhou

    2005-01-01

    The permeability of lightweight aggregate concrete was studied. Some efforts were taken to increase the resistance of lightweight aggregate concrete (LC) to water penetration by using the mineral admixtures of fly ash, granulated blast furnace slag or silica fume. Accelerated chloride penetrability test and liquid atmosphere press method were used to study the anti-permeability of lightweight aggregate concrete. The experimental results show that fly ash, granulated blast furnace slag and silica fume can decrease the permeability of lightweight aggregate concrete, but the effect of granulated blast furnace slag is poor. According to the SEM and pore structure analyzing results,an interface self-reinforcing effect model was presented and the reinforced mechanism of mineral mixture on LC was discussed according to the model described by authors.

  6. Effects of coarse aggregate on compressive strength of dam concrete. Damu concrete no asshuku kyodo ni oyobosu sokotsuzai no eikyo

    Umehara, H.; Ueda, M. (Nagoya Inst. of Technology, Nagoya (Japan). Faculty of Engineering); Zhang, J. (Yahagi Construction Ltd., Nagoya (Japan)); Yoshida, H. (Nagoya Inst. of Technology, Nagoya (Japan))

    1992-08-20

    Compressive strength of coarse aggregate as well as the bond between coarse aggregate and cement paste effect the compressive strength of concrete greatly. Furthermore the said bond is affected by the bleeding. Consequently, to grasp the level of the voids, under the bottom of the coarse aggregate, caused by the bleeding is the most important in estimating the compressive strength of concrete. However, the researches by now are almost performed on the specimens with Gmax (maximum size of coarse aggregate) being less than 40 mm, and there is nearly none being carried out on a specimen such as dam concrete comprising Gmax as around 150 mm. Now, in the present study, the mechanism of the deterioration of compressive strength in dam concrete due to the voids under the bottom of coarse aggregate is clarified based on the experiment carried out on the alterations of the size, shape, number. location and surface states of the model coarse aggregate in the prepared model concrete made by mortar with Gmax as more than 80 mm. 16 refs., 9 figs., 5 tabs.

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

    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. PMID:19709870

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

    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...

  9. Integrating service-life modeling and life-cycle assessment for recycled-aggregate concrete

    Bergman, Todd Lee

    The development and implementation of one-dimensional (a) analytical and (b) numerical service-life models for chloride-induced corrosion of reinforced concrete containing both recycled-aggregates and supplementary cementitious materials (SCMs) are presented in this work. Both the analytical and numerical models account for initial chloride contamination levels due to previous applications. The effects of aggregate type (e.g., virgin, recycled aggregate, recycled mortar), aggregate replacement ratio, severity of chloride contamination levels, severity of in-service chloride exposure, reinforcement cover depth, SCM type (e.g., fly ash, slag, slice fume, metakaolin), and SCM replacement ratio on the expected service life of recycled-aggregate reinforced concrete were investigated. Results illustrated trends between concrete mixes and life cycle costs, which were employed to make conclusions on the trade-offs presented by cost, sustainability, and service life.

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

    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. PMID:27297045

  11. The prediction of the freeze/thaw durability of coarse aggregate in concrete by mercury intrusion porosimetry

    Lindgren, M. N.

    1980-10-01

    Aggregates from fifty-two Indiana highway cores were tested as were five rock samples supplied by the Portland Cement Association. The Expected Durability Factor values were determined from the pore size distributions, and an average value was assigned to each pavement associated with the cores. These values were then compared with the field performance of the pavement to ascertain the borderline between EDF values for durable and for nondurable aggregates. A good correlation between the field performance and the average EDF values was found. A pavement will be durable if its coarse aggregate has an EDF value greater than 50 for 90% or more of the aggregate. This criterion applies to stone and gravel aggregates with a maximum size of 1-1/2 to 2-1/2 inches. The pavement will be durable for at lest thirty years.

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

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

    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 o...

  13. The Aggregate Gradation for the Porous Concrete Pervious Road Base Material

    YANG Zhifeng; MA Wei; SHEN Weiguo; ZHOU Mingkai

    2008-01-01

    The effects of the proportion of fine aggregate, the maximum size of the aggregate and the proportion of the 9.5mm to 4.75mm particle in the coarse aggregate on the properties of the porous concrete are investigated. Results indicate that the porous concrete with a cement dosage only 150kg/m3 has high strength and satisfying permeability when the aggregate has a passing percentage of 4.75mm around 10% to 5%, with the increase of the maximum size of the aggregate, the strength of the porous concrete decreases and the permeability increases. When the proportion of the 9.5mm to 4.75mm particle in the coarse aggregate is about 20%, there are no interference among the particles by Weymouth theory, the strength of the pervious porous concrete reaches the peak value. The optimum continues gradation limit of the aggregate for porous concrete pervious road base material is recommended according to the theoretical calculation and experimental results.

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

    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

  15. Influence of crushed stone aggregate type on concrete consistency

    Topličić-Ćurčić Gordana; Grdić Zoran; Despotović Iva; Ristić Nenad

    2010-01-01

    The main reason for usage of crushed stone mineral aggregate is need for concrete construction building with care about environmental protection, water resources, etc. Influence of crushed stone mineral aggregate on concrete consistency is considered in this paper. River aggregate is used as a benchmark, and from crushed aggregates: limestone, andesite, diabase and basalt. The drawn conclusion is that fine crushed aggregate has an important influence on concrete consistency because it decreas...

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

    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. PMID:18691863

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

    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. Assesment of Alkali Resistance of Basalt Used as Concrete Aggregates

    al-Swaidani, Aref M.; Baddoura, Mohammad K.; Aliyan, Samira D.; Choeb, Walid

    2015-11-01

    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.

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

    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)

  20. Compressive Strength, Pore Size Distribution and Chloride-ion Penetration of Recycled Aggregate Concrete Incorporating Class-F Fly Ash

    KOU Shicong; C S Poon

    2006-01-01

    The effects of fly ash on the compressive strength, pore size distribution ard chloride-ion penetration of recycled aggregate concrete were investigated. Two series of concrete mixtures were prepared. The concrete mixtures in series I had a water-to-binder ratio and a cement content of 0.55 and 410 kg/m3 , respectively. The concrete mixtures in series Ⅱ had a water-to-binder ratio and a cement content of 0.45 and 400 kg/m3 respectively. Recycled aggregate was used as 20% , 50% , and 100% replacements of natural coarse aggregate in the concrete mixtures in both series. In addition, fly ash was used as 0% , 25% and 35% by weight replacements of cement. The results show that the compressive strengths of the concrete decreased as the recycled aggregate and the fly ash contents increased. The total porosity and average porosity diameter of the concrete increased as the recycled aggregate content increased. Furthermore, an increase in the recycled aggregate content decreased the resistance to chloride ion penetration. Nevertheless, the replacement of cement by 25% fly ash improved the resistance to chloride ion penetration and pore diameters and reduced the total porosity of the recycled aggregate concrete.

  1. Effect of fine ceramic recycled aggregate (RA) and mixed fine RA on hardened propertiesof concrete

    Etxeberria Larrañaga, Miren; Vegas, Iñigo

    2015-01-01

    Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees The ceramic industry is well known for producing large amounts of rejected ceramic waste. During the construction and demolition waste crushing process, a large amount of fine recycled aggregates (FRA) are usually produced. However, little research work has been carried out employing those types of aggregates in recycled aggregate concrete (RAC) production...

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

    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. PMID:24453830

  3. Microstructure Analysis to the LILW Concrete Structures by Environment Factor

    LILW Concrete structures located on the seashore are affected by chloride attack, sulfuric acid, and carbonation. In addition, as the life of structure is extended, it requires a precise evaluation of its durability. Therefore, this study was aimed at the validity of such techniques used to evaluate a concrete structure where a analysis techniques were applied to the changes in the concrete microstructure following a chloride attack degradation environments, and thereby exploring such changes in microstructure

  4. Utilization of Recycled Concrete Aggregates in Stone Mastic Asphalt Mixtures

    Mohammad Saeed Pourtahmasb

    2014-01-01

    Full Text Available Recycled concrete aggregate (RCA is considered as one of the largest wastes in the entire world which is produced by demolishing concrete structures such as buildings, bridges, and dams. It is the intention of scientists and researchers, as well as people in authority, to explore waste material recycling for environmental and economic advantages. The current paper presents an experimental research on the feasibility of reusing RCA in stone mastic asphalt (SMA mixtures as a partial replacement of coarse and fine aggregates. The engineering properties of SMA mixtures containing RCA have been evaluated for different percentages of binders based on the Marshall mix design method. The outcomes were statistically analyzed using two-factor analysis of variance (ANOVA. Test results revealed that the performance of SMA mixtures is affected by RCA due to higher porosity and absorption of RCA in comparison with virgin granite aggregates. However, the engineering properties of SMA mixtures containing a particular amount of RCA showed the acceptable trends and could satisfy the standard requirements. Moreover, to achieve desirable performance characteristics, more caution should be made on properties of SMA mixtures containing RCA.

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

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

    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...

  6. Chloride corrosion of embedded reinforced steel on concrete elaborated from recycled coarse aggregates and supplementary cement materials

    Corral Higuera, Ramón; Arredondo Rea, Susana Paola; Almaral Sánchez, Jorge Luis; Gómez Soberón, José Manuel Vicente

    2013-01-01

    As a result of contributive and sustainable strategies on concrete industry, researches are presently being developed, which are focused on improving durability of reinforced concrete structures as well as partially or completely replacing their components by recycled materials. In the case of steel bars, corrosion is considered as the major durability menace to reinforced concrete. The present research employed coarse aggregate from recycled concrete and supplementary cement materials,...

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

    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. PMID:16574393

  8. DURABILITY OF ASPHALT CONCRETE MIXTURES USING DOLOMITE AGGREGATES

    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.

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

    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.

  10. Shrinkage of Concrete using Porous Aggregates

    Valgeir Ó. Flosason 1987

    2014-01-01

    During its service life, concrete undergoes volume changes which can affect quality and durability of the concrete. There are several types of volume changes, but shrinkage is the type of volume change which is often responsible for cracking of the concrete. Shrinkage can be categorized due to several different mechanisms which cause shrinkage. The main types of shrinkage are plastic shrinkage, chemical shrinkage, autogenous shrinkage, drying shrinkage and carbonation shrinkage. In this ma...

  11. Flexural Fatigue performance of Alkali Activated Slag Concrete mixes incorporating Copper Slag as Fine Aggregate

    Mithun B.M.

    2015-06-01

    Full Text Available The present investigation attempts a detailed study of mechanical properties and fatigue characteristics of a new class of Alkali Activated Slag Concrete (AASC mixes incorporating Copper Slag (CS as fine aggregates. The natural river sand is replaced with Copper Slag, upto 100% (by volume as fine aggregate in these AASC mixes. The behavior of plain concrete prisms, cast with this range of AASC mixes under dynamic cyclic loads with sand/CS fine aggregates is studied and is compared with conventional OPC-based concrete specimens. The results indicate that incorporation of CS even upto 100% as fine aggregates, did not have any adverse effects on the mechanical properties of AASC mixes. The AASC mixes with CS displayed slightly better fatigue performance as compared to AASC mix with river sand. An attempt is also made herein to statistically describe the fatigue life data of AASC mixes using a 2-parameter Weibull distribution.

  12. Use of recycled and secondary aggregates in concrete: an overview

    Dhir, Ravindra; Paine, K.A.; J. Brito; Etxeberria Larrañaga, Miren; Ho, N.Y.; Poon, C S; Tam, V.W.Y.

    2011-01-01

    This paper written by some of the world’s leading exponents on the use of recycled and secondary aggregates provides a brief overview of the use of recycled and secondary aggregates for new concrete construction. It is based on a substantial review, dissection and repackaging of the current known knowledge in the field and is based on authors’ own research, findings and experience. The paper, in particular, draws upon recent knowledge that has been generated in the past five years as standard...

  13. Study on Expansion Cracking of Hydration in Concrete Aggregates

    2002-01-01

    In accordance with a fresh accident by severe expansion cracks of structural elements,based on systematic detection and analyses such as X-ray diffraction,differential thermal analysis,scanning electron microscory,chemical analysis,petrographic analysis, electronic probe analysis,and atomic absorption spectroscopy analysis, it is pointed out that the dominant reasons lie in the hydration reaction of magnesia in concrete aggregates, resulting in a volume expansion in structure members.A wholly new corresponding strengthening method is applied to the cracked elements and turned out to be effective.

  14. Studies on eco-friendly concrete incorporating industrial waste as aggregates

    Nitendra Palankar

    2015-12-01

    Full Text Available The present day research is focussed on development of alternative binder materials to Ordinary Portland Cement (OPC due to huge emissions of green house gases associated with production of OPC. GGBFS-FA based geopolymer binders are an innovative alternative to OPC which can obtain high strengths apart from being eco-friendly; since its production does not involve high energy and also contributes to sustainability by using the industrial waste materials. Steel slag, an industrial by-product obtained from manufacture of steel can be identified as an alternative to natural aggregates for concrete production, since there is a possibility of acute shortage of natural aggregates in future. The present study is conducted to evaluate the performance of weathered steel slag coarse aggregates in GGBFS-FA based geopolymer concrete. GGBFS-FA geopolymer concrete with steel slag coarse aggregates are prepared by replacing natural granite aggregates at different replacement levels i.e. 0%, 25%, 50%, 75% and 100% (by volume and various fresh and mechanical properties are studied. The flexural fatigue behaviour of GGBFS-FA geopolymer concrete with steel slag is also studied in detail. Efforts are also made to model the probabilistic distribution of fatigue data of GGBFS-FA geopolymer concrete at different stress levels using two parameters Weibull distribution. The results indicated that incorporation of steel slag in GGBFS-FA geopolymer concrete resulted in slight reduction in mechanical strength. The water absorption and volume of permeable voids displayed higher values with inclusion of steel slag. Reduction in number of cycles for fatigue failure was observed in geopolymer concrete mixes containing steel slag as compared to granite aggregates. Overall, the performance of steel slag was found to be satisfactory for structural and pavement application and steel slag can be recognised as new construction material.

  15. Application of Recycled Concrete Aggregates Containing Waste Glass Powder/Suspension and Bottom Ash as a Cement Component in Concrete

    Kara, P

    2013-01-01

    The growing environmental concerns and the increasing scarcity of landfills encourage the recycling of industrial wastes and adopting environmentally friendly practices by rational usage of natural resources. The production of concrete with recycled aggregate and reduced cement volume is the most desirable form of achieving a closed life cycle as an ecological constructional material. This paper describes results of a study undertaken to examine the influence of recycled aggregates obta...

  16. Health monitoring of reinforced concrete shear walls using smart aggregates

    In this paper, a smart aggregate-based approach is proposed for the structural health monitoring of a concrete shear wall structure. The piezoceramic-based smart aggregates were distributed in predetermined locations prior to the casting of the concrete structure to form an active-sensing system for the health monitoring purpose. To evaluate the damage in different areas, the concrete shear wall was sectioned into sub-domains and a wavelet-packet-based damage index matrix is proposed to evaluate the health status in these sections. A cyclic loading procedure was applied to gradually fail the concrete shear wall and the proposed structural health monitoring approach was used to perform structural health monitoring during this loading procedure. The experimental results have shown that the proposed smart aggregate-based approach effectively evaluated the damage status in different areas and detected the precautionary point to predict the structural failure. The proposed approach has the potential to be applied to the structural health monitoring of large-scale concrete shear wall structures. (technical note)

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

    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.

  18. Experimental investigations on mode II fracture of concrete with crushed granite stone fine aggregate replacing sand

    Kanchi Balaji Rao

    2012-02-01

    Full Text Available With a view to implement sustainability concepts (namely, use of locally available materials and industrial by-products in the concrete construction industry, the possibility of use of crushed stone fine aggregate as replacement to river sand is explored in this paper. Towards this, tests have been carried out on concrete cubes and concrete cylinders. The effect of variation in percentage replacement of river sand with crushed stone fine aggregate on the mechanical properties is studied. In order to popularize the locally available material for the construction of shear critical concrete structures (viz. flat slabs, foundation of heavy structures, the Mode - II fracture behavior of the considered concrete is studied using DCN (Double Central Notched specimens with different notch to depth, (a/w, ratios of 0.3, 0.4, 0.5 and 0.6. For each (a/w ratio five different percentage replacements (viz. 0, 25, 50, 75 and 100% are considered. The study indicates that both cube compressive strength and split tensile strength increases with the increase in percentage replacement up to 50% and then gradually decreases. A similar observation was made with respect to the Mode - II fracture energy also. It is noted that the strengths of concrete even with 100% replacement are higher than the concrete with 0% replacement suggesting that the locally available crushed stone fine aggregate can be considered as an alternative to the river sand.

  19. Use of Steel Slag as Coarse Aggregate for the Production of Pervious Concrete

    Georgia Vardaka; Kiriakos Thomaidis; Christos Leptokaridis; Stamatis Tsimas

    2014-01-01

    Pervious concrete is a type of concrete with significantly increased water permeability, ensuring increased rates of drainage of rainfall. The high porosity is achieved by removing a large percentage of fine aggregates from the mix. The present paper is an approach for the addition of steel slag as a substitute for coarse aggregates in pervious concrete. More specifically, three types of aggregates have been used: steel slag, construction and demolition wastes and conventional limestone aggre...

  20. Evaluation Of Flexure Strength Behavior Of Over Burnt Brick Ballast Aggregate Concrete

    Tariq Ali; Nouman Iqbal

    2014-01-01

    Regional conditions enforced engineers to generate a study on concrete which incorporate Over Burnt Brick Ballast Aggregate partially due to their abundance. 5%, 10%, 15%, and 20% (M05, M10, M15, M20) incorporation was used as partial replacement of natural coarse aggregate in concrete. Analysis of incorporated concrete was done in fresh state as well in hardened state to evaluate different properties of concrete i.e. slump value, compaction factor value, unit weight, flexural...

  1. Use of steel slag aggregate in asphalt concrete mixes

    Asi, I.M.; Qasrawi, Y.; Shalabi, F.I. [Hashemite Univ., Zarqa (Jordan). Dept. of Civil Engineering

    2007-08-15

    The physical, chemical and mechanical properties of generated steel slag aggregates (SSA) were studied in order to investigate their potential use in asphalt concrete (AC) mixes. Five AC mixes were investigated, notably an AC mix with a 100 per cent limestone aggregate, and mixes comprised of 25, 50, 75, and 100 per cent SSA coarse aggregates. A superpave mix design was used to determine optimum asphalt content (OAC). Steps included the selection of a design aggregate structure, optimization of the asphalt content for the structure, and an evaluation of the moisture sensitivity of the design mixture. The effectiveness of the samples were assessed by their ability to improve indirect tensile strength (ITS); resilient and creep modulus; fatigue life; and stripping and rutting resistance. Various AC mixes containing the SSA were then evaluated. A gyratory compactor was used to compact the test samples, which were then subjected to comprehensive mechanical evaluations. Statistical analyses were then performed to examine the significance of the SSA percentage in the changing ITS values using analysis of variance (ANOVA) calculations. Results of the study indicated that SSA met both superpave consensus properties and Jordanian standards source properties. Chemical and toxic levels were within allowable limits. It was concluded that optimal the replacement percentage of SSA was 25 per cent. 18 refs., 9 tabs., 21 figs.

  2. Effect of Different Coarse Aggregate Sizes on the Strength Characteristics of Laterized Concrete

    Salau, M. A.; Busari, A. O.

    2015-11-01

    The high cost of conventional concrete materials is a major factor affecting housing delivery in developing countries such as Nigeria. Since Nigeria is blessed with abundant locally available materials like laterite, researchers have conducted comprehensive studies on the use of laterite to replace river sand partially or fully in the concrete. However, the works did not consider the optimum use of coarse aggregate to possibly improve the strength of the laterized concrete, since it is normally lower than that of normal concrete. The results of the tests showed that workability, density and compressive strength at constant water-cement ratio increase with the increase in the coarse aggregate particle size and also with curing age. As the percentage of laterite increases, there was a reduction in all these characteristics even with the particle size of coarse aggregate reduction due to loss from the aggregate-paste interface zone. Also, when sand was replaced by 25% of laterite, the 19.5mm and 12.5mm coarse aggregate particle sizes gave satisfactory results in terms of workability and compressive strength respectively at 28 days of curing age, compared to normal concrete. However, in case of 50% up to 100% laterite contents, the workability and compressive strength values were very low.

  3. Egg Shell As A Fine Aggregate In Concrete For Sustainable Construction

    S.A. Raji

    2015-08-01

    Full Text Available ABSTRACT This work has investigated the potential use of usedegg shell as a concrete material. The usedegg shells were used as fine concrete aggregate. In the laboratory test conventional fine aggregate was replaced at 100 replacement level. A total of 18 cubes were cast cured and tested. The strength development of the concrete mixes containing egg shell aggregates was compared to that of conventional concrete with sand as fine aggregate. The result showed a reduction in compressive strength of the concrete but still falls within limits of lightweight concrete. This paper recommends that egg shell can be used for producing concrete where a lighter weight concrete is required and a reduction of dead load of structure is desired.

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

    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 p

  5. Lightweight Aggregate Concrete. The materials in the precast elements

    Goltermann, Per; Larsen, Henning; Ingholt, N.U.

    1996-01-01

    The precast lightweight aggregate concrete (LAC) elements are used extensively in Denmark, where the use of precast elements domonates the building structures. Similar elements are used in other parts of Nothern Europe, which have lead to development of an European standard for precast LAC elements...

  6. Effect of fine to coarse aggregate ratio on the rheology and fracture energy of steel fibre reinforced self-compacting concretes

    Mert Yücel Yardimci; Bülent Baradan; Mehmet Alı Taşdemır

    2014-12-01

    In this study, the influence of aggregate grading and steel fibre properties on the flow properties and fracture energy of steel fibre reinforced self-compacting concrete (SFRSCC) has been investigated. Two types of hooked-end steel fibres at three different dosages (20, 40 and 60 kg/m3) were incorporated into self-compacting mixtures having similar paste contents but different fine to coarse aggregate (FA/CA) ratios (0.94, 1.72 and 2.50 by weight). Besides the flowability and passing ability of fresh concrete, the mechanical properties of hardened concrete including the fracture energy have also been investigated. The relations between flexural parameters and fibre orientation were established by image analysis technique. Test results showed that hooked-end steel fibre inclusion into the plain self-compacting concrete negatively affects the flowability and passing ability of themixture. Increasing FA/CA ratio enhances these rheological parameters and provides better fibre orientation. On the other hand, increasing FA/CA ratio decreases the fracture energy of plain SCC mixtures and the fibre incorporated series which were less affected from fibre inclusion follow the same trend with the plain SCC. The proper FA/CA ratio for the best rheological and mechanical performance depends on the fibre content, aspect ratio and their influence on the flowability of the mixture. In order to obtain better fibre orientation and hence higher fracture energy, relatively higher FA/CA ratios should be used when the fibre content and aspect ratio are relatively high.

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

    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.

  8. Flexural fatigue characteristics of steel fiber reinforced recycled aggregate concrete (SFRRAC)

    Heeralal M.; Kumar Rathish P.; Rao Y.V.

    2009-01-01

    This research work is aimed at investigating the flexural fatigue behavior of Steel Fiber Reinforced Recycled Aggregate Concrete (SFRRAC). This study gains importance in view of the wide potential for demolished concrete to serve as a source of quality aggregate feed stock in a variety of structural and non-structural applications. This is a continuation of a series of investigations being conducted aimed at optimizing the utilization of recycled aggregate concrete in rigid pavements. A total...

  9. Compression Dispersion Efficiency of Recycled Aggregate Concrete Struts At Different Load Concentration Ratios

    Dr. Rakesh Kumar, Dr.P.K Mehta,Devbrat Singh, Anup Kumar Pandey, Sarvesh Kumar

    2014-06-01

    Full Text Available Infrastructure development activities in India have increased many folds in recent times. This has resulted in increase in the demand of construction materials like cement, coarse aggregate, fine aggregate etc. Huge quantities of concrete wastes are produced due to demolition of old structures. If recycled aggregate from this waste is used for construction purpose, it will not only make the structures economical and eco-friendly butwill also solve the problem of waste disposal.Recycling old waste concrete by crushing and grading into coarse aggregates for use in new structural concrete is drawing the attention of engineers, environmentalists and researchers since last three decades. In this paper, an attempt has been made to study the compression dispersion behaviour of struts of natural coarse aggregate (NCA and recycle coarse aggregate (RCA at different load concentration ratio and aspect ratio. For the study, struts of 450 mm height and 75mm thickness with varying widths starting from 75mm to 450mm, using NCA and RCA concrete, were cast. The testing of struts was carriedout on loading frame of capacity 500 kN. The struts were tested to failure under in-plane compressive load applied through symmetrically placed steel plate (75×75×10 mm at top andbottom of the struts.

  10. A Novel Method to Quantify Soil Aggregate Stability by Measuring Aggregate Bond Energies

    Efrat, Rachel; Rawlins, Barry G.; Quinton, John N.; Watts, Chris W.; Whitmore, Andy P.

    2016-04-01

    Soil aggregate stability is a key indicator of soil quality because it controls physical, biological and chemical functions important in cultivated soils. Micro-aggregates are responsible for the long term sequestration of carbon in soil, therefore determine soils role in the carbon cycle. It is thus vital that techniques to measure aggregate stability are accurate, consistent and reliable, in order to appropriately manage and monitor soil quality, and to develop our understanding and estimates of soil as a carbon store to appropriately incorporate in carbon cycle models. Practices used to assess the stability of aggregates vary in sample preparation, operational technique and unit of results. They use proxies and lack quantification. Conflicting results are therefore drawn between projects that do not provide methodological or resultant comparability. Typical modern stability tests suspend aggregates in water and monitor fragmentation upon exposure to an un-quantified amount of ultrasonic energy, utilising a laser granulometer to measure the change in mean weight diameter. In this project a novel approach has been developed based on that of Zhu et al., (2009), to accurately quantify the stability of aggregates by specifically measuring their bond energies. The bond energies are measured operating a combination of calorimetry and a high powered ultrasonic probe, with computable output function. Temperature change during sonication is monitored by an array of probes which enables calculation of the energy spent heating the system (Ph). Our novel technique suspends aggregates in heavy liquid lithium heteropolytungstate, as opposed to water, to avoid exposing aggregates to an immeasurable disruptive energy source, due to cavitation, collisions and clay swelling. Mean weight diameter is measured by a laser granulometer to monitor aggregate breakdown after successive periods of calculated ultrasonic energy input (Pi), until complete dispersion is achieved and bond

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

    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.

  12. Mechanical Characteristic of Pervious Concrete Considering the Gradation and Size of Coarse Aggregates

    Alireza Joshaghani; Ali Akbar Ramezanianpour; Mohammad Jaberizadeh

    2014-01-01

    Pervious concrete is a kind of sustainable pavement with high permeability which is becoming more common as a storm water management. The purpose of this study was to investigate the effects of coarse aggregate on physical and mechanical properties of the pervious concrete such as density, strength, porosity and permeability at 7, 28, 56 days. This experimental investigation conducted by comparing nine different mixtures. Taguchi design of experiments used to optimize the performance of these...

  13. Shrinkage of Hong Kong granite aggregate concrete

    Kwan, AKH; Au, FTK; Wong, HHC; Ng, PL

    2010-01-01

    In the design of many concrete structures, it is important to assess the amount of shrinkage that could occur because shrinkage could lead to extensive cracking or substantial prestress loss. A number of shrinkage models have been developed all over the world but they differ widely from each other, indicating that the shrinkage of concrete is dependent on the characteristics of the materials used and the local conditions. Early experimental studies in Hong Kong suggested that the shrinkage of...

  14. Sustainable High Quality Recycling of Aggregates from Waste-to-Energy, Treated in a Wet Bottom Ash Processing Installation, for Use in Concrete Products

    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.

  15. The Properties and Characteristics of Concretes Containing Calcium Carbonate (CaCO3) and Synthetic Lightweight Aggregate

    Ramos, Matthew J.

    The purpose of this study was to investigate the efficacy of precipitated calcium carbonate as a means for enhancing the mechanical and environmental favorability of concretes containing synthetic lightweight aggregates (SLA), which are comprised of recycled mixed plastic and fly ash. Compressive strength tests show that 2% calcium carbonate additions are able to mitigate strength decreases induced by SLA as well as decrease concrete density when compared to NWA concretes. SLA concretes containing 5% calcium carbonate do not show the same trend. Instead, strength decreases and density increases are observed. Furthermore, increases in aluminum trisulphate (AFt) phase mineralization are observed through scanning electron microscopy. Results suggest that calcium carbonate additions increase early hydration and stabilize AFt minerals thaumasite and ettringite throughout hydration. It is proposed that increased AFt phase mineralization causes reductions in concrete density. However, a limit to this relationship was observed as additions of greater than 2% calcium carbonate exceed the potential for increased hydration, causing a threshold effect that resulted in calcium carbonate acting as filler, which increases density. Improved mechanical properties and the ability to stabilize waste plastics, fly ash, and CO2 emissions make the use of 2% calcium carbonate in conjunction with SLA a favorable alternative to ordinary concretes.

  16. The influence of granulation on lightweight aggregate on early autogenous shrinkage of high strength concrete

    Maleš, Dijana

    2013-01-01

    Early autogenous shrinkage of high strength concretes is relatively large. It can be reduced by using internal water reservoirs. Lightweight aggregate was used for internal water reservoir. 12% of aggregate was replaced with pre-soaked lightweight aggregate in the concrete mixture. On the basis of experiments in the graduation thesis we studied the influence of granulation of lightweight aggregate on early autogenous shrinkage. The shrinkage was measured electronically during the first day. I...

  17. Effect of NGBFS and CBA as fine aggregate on the chloride permeability of concrete

    İsa Yüksel

    2013-09-01

    Full Text Available This paper presents the results of an investigation which was about influence of non-ground Coal Bottom Ash (CBA and Non-Ground Granulated Blast-Furnace Slag (NGBFS as fine aggregate on rapid chloride permeability of concrete. Series of Rapid Chloride Permeability Test (RCPT were conducted with concrete specimens containing NGBFS and CBA in varying percentages from 10 to 50% with the step of 10% of fine aggregate by weight. Two basic series concrete specimens were prepared in laboratory. The first series (G was contained NGBFS, the second series (B was contained CBA as fine aggregate. Test results indicated that NGBFS or CBA improves the resistance to chloride ion penetration tosome extent. 30% and 10% replacement ratios were selected as optimum replacement ratios for G and B series. It was concluded that GBFS was more impressive then CBA for blocking chloride ion movements.

  18. Use of Steel Slag as Coarse Aggregate for the Production of Pervious Concrete

    Georgia Vardaka

    2014-03-01

    Full Text Available Pervious concrete is a type of concrete with significantly increased water permeability, ensuring increased rates of drainage of rainfall. The high porosity is achieved by removing a large percentage of fine aggregates from the mix. The present paper is an approach for the addition of steel slag as a substitute for coarse aggregates in pervious concrete. More specifically, three types of aggregates have been used: steel slag, construction and demolition wastes and conventional limestone aggregates. The produced pervious concretes are compared for their properties, such as water permeability, compressive strength and abrasion behaviour. Also this paper contains the study of the porosity analysis of these pervious concrete mix designs by using porosity profiles produced from X-ray CT Scanning. According to the results of this paper, it is observed that the incorporation of industry by-products or of Construction and Demolition (C&D wastes leads to better abrasion behaviour, and to the increase, in some cases, of the compressive strength and of the water permeability.

  19. Compressive and Tensile Capacity of Recycled Aggregate Concrete (RAC with Glass as Supplement Material

    Suraya Hani Adnan

    2013-12-01

    Full Text Available The amount of construction waste is increased significantly over the years due to reconstruction and the demolition of old buildings. One of the major challenges of our present society is to protect the environment by recycling the existing construction waste. This study concerned on two types of variable in the production of concrete which are the utilization of coarse recycled aggregate and utilization of different supplement ratio of fine glass wastes to cement. To evaluate the viability of this study, an experimental work was performed in order to monitor the mechanical behavior of such concrete. The compression and splitting tensile strength of concrete were determined on this study. From the result, it is conclude that the utilization of recycled aggregate does not much affect in the uniaxial compressive strength and splitting tensile strength of concrete, for replacement ratio up to 25 %. However, the utilization of fine glass as supplement material to cement is increase the uniaxial compressive and splitting tensile strength of concrete, for supplement ratio up to 5 %. Thus, it can be stated that the optimum concrete mixture is the mixture of 25 % recycled aggregate and 5% glass.

  20. Durability of recycled aggregate concrete designed with the Equivalent Mortar Volume (EMV method: Validation under the Spanish context and its adaptation to Bolomey methodology

    Jiménez, C.

    2014-03-01

    Full Text Available Some durability properties are analyzed in concretes made with a novel method for recycled aggregates concrete (RAC proportioning, in order to validate it under the Spanish context. Two types of concrete mixes were elaborated; one following the guidelines of the named method, and other based on an adaptation of the method to Bolomey methodology. Two types of recycled concrete aggregates (RCA were used. RCA replacement for natural aggregates (NA ranged from 20% to 100%. The 20% was chosen in order to comply with Spanish recommendations. Water penetration under pressure, water absorption and chlorides attack were the studied properties. It is verified that the new method and the developed adaptation results in concrete mixes of better or similar properties to those of the natural aggregates concrete (NAC and the conventional RAC, saving important amounts of cement.Algunas propiedades de durabilidad son analizadas en hormigones elaborados con el nuevo método para la dosificación de hormigones con árido reciclado (HAR para validarlo bajo el contexto español. Se elaboraron dos tipos de hormigones; uno siguiendo las directrices del nuevo método y otro basado en una adaptación del anterior a la metodología Bolomey. Se utilizaron dos tipos de árido reciclado (ARH. Los reemplazos de áridos variaron entre 20% y 100%. El 20% ha sido elegido para cumplir con recomendaciones españolas sobre HAR. Las propiedades estudiadas fueron: penetración de agua bajo presión, absorción de agua y susceptibilidad al ataque de cloruros. Se verifica que el nuevo método y la adaptación desarrollada resultan en hormigones con mejores o similares características que las de un hormigón con áridos naturales (HAN y las de HAR convencional, ahorrando, además, importantes cantidades de cemento.

  1. 再生细骨料取代率对混凝土工作性的影响%Effects on Substitution Rate of Recycled Fine Aggregate to Concrete Workability

    2015-01-01

    以不同流动性的混凝土再生细骨料取代率为变化因素,对混凝土初始坍落度、1 h 坍落度、快速工作度以及28 d 抗压强度进行了测试。研究表明,不同流动性的再生混凝土再生细骨料总比例在30%~40%左右变化时,对混凝土工作性影响不大,再生混凝土的强度甚至高于基准混凝土;在保持再生混凝土配合比其他掺量不变条件下,再生细骨料对坍落度要求较高的混凝土适应性较好,最高取代率为30%。通过快速工作度测定方法建立了混凝土快速工作度与坍落度之间的关系,为快速推算混凝土坍落度并实时监控混凝土施工状态提供参考。%The initial concrete slump,1 h slump ,fast workability and 28 day compressive strength were tested,re-spectively on the substitution rate of the recycled fine aggregate with the different mobility of concrete.The research showed that the influence on the workability of concrete was little,recycled concrete strength even higher than that of the reference concrete,at the recycled aggregate proportion in the change of 30%~40%.In the condition of the con-stant concrete mixture proportion keeping other content of the recycled concrete,it was more suitable for the fine ag-gregate to the concrete with higher slump,the highest substitution rate of 30%.Through the method of fast workabili-ty determination,the relationship between the concrete fast workability and slump was established .It was provided for the rapid calculation of concrete slump and monitoring the concrete construction in real-time.

  2. 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

    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.

  3. Relationship between pore structure and mechanical properties of ordinary concrete under bending fatigue

    Zhang, B. [Univ. of Glasgow (United Kingdom). Dept. of Civil Engineering

    1998-05-01

    Progressive macro damage of concrete under fatigue loading is caused by the change of its internal micro-meso properties such as pore structure. In this study, porosity, pore size distribution, and specific surface area of ordinary concrete at different fatigue stages were investigated using mercury intrusion, helium flow, and nitrogen adsorption (BET) methods. These properties changed with increasing loading cycles and could be taken as micro-meso damage parameters to evaluate macro fatigue damage of concrete. Test results showed that both porosity in mortar (mainly macro pores) and interface between mortar and coarse aggregates (interfacial cracks) developed at a similar rate. The corresponding residual bending fatigue strength and dynamic bending Young`s modulus were also obtained and their relationships with these micro-meso properties were established. The intrinsic bending strength and intrinsic bending Young`s modulus were predicted from these relationships.

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

    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

  5. Anchorage of Main Reinforcement in Lightweight Aggregate Concrete Beams

    Larsen, Henning

    1999-01-01

    The paper deals with the anchorage of reinforcement bars at end supports in beam component made of lightweight aggregate concrete with open structure.......The paper deals with the anchorage of reinforcement bars at end supports in beam component made of lightweight aggregate concrete with open structure....

  6. Influence of Electric Arc Furnace (EAF Slag Aggregate Sizes on the Workability and Durability of Concrete

    P. O. Awoyera

    2015-06-01

    Full Text Available The construction industry has been identified as one of the largest consumer of nonrenewable resources. Meanwhile, the unused materials are continually disposed in landfills and dumpsites. As a result, adoption of industrial solid wastes for use as a construction material remains pertinent in the creation of a green environment. The present study focused on the influence of EAF steel slag aggregate (SSA sizes on the workability and durability of concrete. Concrete mixes in 1:2:4 ratios of cement, sand and SSA; batched by weight, and a water cement ratio of 0.6 were considered. However, a control mix using normal aggregate (NA was made in order to evaluate the variation in properties of the concretes. The study utilised SSA and NA sizes of ½ inch (12.7 mm, 3/8 inch (9.54 mm and ¾ inch (19.05 mm respectively. All testing were conducted under room temperature, adopting procedures recommended in BS standards. For all the aggregate sizes considered, SSA produced an appreciable 28 day compressive strength than the NA concrete. However, the NA concrete possess good workability than the SSA concrete.

  7. Study on relationships between strength indexes of recycled glass coarse aggregate concrete%再生玻璃粗骨料混凝土强度指标换算关系研究

    李爱飞; 梁炯丰; 罗锟

    2014-01-01

    Based on the experimental data,the relationships between the cubic compressive strength and other strength are obtained.The results showed that the every strength of waste glass recycled coarse aggregate concrete was lower than ordinary concrete and the inter-re-lationships of strength indexes of waste glass recycled coarse aggregate concrete is different from that ordinary concrete.%在试验数据的基础上,通过统计回归,初步给出了再生玻璃粗骨料混凝土立方体抗压强度与其他强度指标之间的换算关系。试验结果表明:再生玻璃粗骨料混凝土各种强度均比普通混凝土要低,其强度换算关系并不同于普通混凝土。

  8. Study of the seismic response of a recycled aggregate concrete frame structure

    Wang, Changqing; Xiao, Jianzhuang

    2013-12-01

    Based on six-degree-of-freedom three-dimensional shaking table tests, the seismic response of a recycled aggregate concrete (RAC) frame was obtained. The analysis results indicate that the maximum story shear force and overturning moment reduce proportionally along the height of the model under the same earthquake wave. The story shear force, base shear coefficient and overturning moment of the structure increase progressively as the acceleration amplitude increases. The base shear coefficient is primarily controlled by the peak ground acceleration (PGA). The relationships between the PGA and the shear coefficient as well as between the PGA and the dynamic amplification factor are obtained by mathematical fitting. The dynamic amplification factor decreases rapidly at the elastic-plastic stage, but decreases slowly with the development of the elastic-plasticity stage. The results show that the RAC frame structure has reasonable deformability when compared with natural aggregate concrete frame structures. The maximum inter-story drift ratios of the RAC frame model under frequent and rare intensity 8 test phases are 1/266 and 1/29, respectively, which are larger than the allowable value of 1/500 and 1/50 according to Chinese seismic design requirements. Nevertheless, the RAC frame structure does not collapse under base excitations with PGAs from 0.066 g up to 1.170 g.

  9. Flexural fatigue characteristics of steel fiber reinforced recycled aggregate concrete (SFRRAC

    Heeralal M.

    2009-01-01

    Full Text Available This research work is aimed at investigating the flexural fatigue behavior of Steel Fiber Reinforced Recycled Aggregate Concrete (SFRRAC. This study gains importance in view of the wide potential for demolished concrete to serve as a source of quality aggregate feed stock in a variety of structural and non-structural applications. This is a continuation of a series of investigations being conducted aimed at optimizing the utilization of recycled aggregate concrete in rigid pavements. A total of 72 standard flexure specimens of 100mm x 100mm x 450mm were cast and tested for flexure under both static and fatigue loading. The parameters of the investigation included the different replacements of recycled aggregate in natural aggregate, presence of steel fiber and different stress levels. The study showed that the recycled aggregates can be used in rigid pavements also and the inclusion of fibers can benefit the fatigue performance of recycled aggregate concrete.

  10. Effect of lightweight aggregate intrinsic Strength on lightweight concrete compressive strength and modulus of elasticity

    Videla, C.

    2002-03-01

    Full Text Available The study of Structural Lightweight Concrete (SLC, which is a material generally composed of cement, water and lightweight aggregate, has been mainly focused on developing particular cases. Then, the main objective of this research was to generalise the knowledge of this type of material. Particularly, the effect of replacing conventional coarse aggregate by lightweight aggregate on mechanical properties of concrete was studied. SLC may be conceived as a two -phase material. The first phase, composed of cement, water and siliceous natural sand, is called the "resistant phase", and contributes to the structural strength. The second phase is the lightweight phase, comprised of coarse lightweight aggregate, and it is meant to decrease the concrete density. In this way it would be possible to describe the mechanical behaviour of concrete, based on lightweight aggregate and the cement mortar parameters. The obtained results allow for the proposition of relationships between mechanical properties of SLC (such as compressive strength and modulus of elasticity and the constituent materials properties and amount. At the same time, an easily measured index representing the structural capability of lightweight aggregate is also proposed, this index allows to estimate the potential mechanical properties of concrete which could be obtained by using a particular aggregate.

    El estudio del Hormigón Ligero Estructural (HLE, material compuesto generalmente por cemento, agua y árido ligero, ha estado enfocado principalmente al desarrollo de casos particulares. Por lo anterior, el objetivo principal de esta investigación fue generalizar el conocimiento sobre este material. En particular, la meta de este trabajo fue estudiar el efecto que tiene el reemplazo de árido convencional por un árido ligero, en las propiedades mecánicas del hormigón. El modelo aplicado conceptualiza al HLE como un material de dos fases, una denominada "soportante", constituida

  11. Mechanical Properties of Recycled Aggregate Concrete at Low and High Water/Binder Ratios

    Gai-Fei Peng; Yan-Zhu Huang; Hai-Sheng Wang; Jiu-Feng Zhang; Qi-Bing Liu

    2013-01-01

    This paper presents an experimental research on mechanical properties of recycled aggregate concrete (RAC) at low and high water/binder (W/B) ratios. Concrete at two W/B ratios (0.255 and 0.586) was broken into recycled concrete aggregates (RCA). A type of thermal treatment was employed to remove mortar attached to RCA. The RAC at a certain (low or high) W/B ratio was prepared with RCA made from demolished concrete of the same W/B ratio. Tests were conducted on aggregate to measure water abso...

  12. Influence of sand to coarse aggregate ratio on the interfacial bond strength of steel fibers in concrete for nuclear power plant

    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.

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

    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.

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

    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...

  15. Cellular Concrete Bricks with Recycled Expanded Polystyrene Aggregate

    Juan Bosco Hernández-Zaragoza; Teresa López-Lara; Jaime Horta-Rangel; Carlos López-Cajún; Eduardo Rojas-González; F. J. García-Rodríguez; Jorge Adue

    2013-01-01

    Cellular concrete bricks were obtained by using a lightweight mortar with recycled expanded polystyrene aggregate instead of sandy materials. After determining the block properties (absorption, compressive strength, and tensile stresses), it was found that this brick meets the requirements of the masonry standards used in Mexico. The obtained material is lighter than the commercial ones, which facilitates their rapid elaboration, quality control, and transportation. It is less permeable, whic...

  16. Noise emission of concrete pavement surfaces produced by diamond grinding

    Jens Skarabis

    2015-04-01

    Full Text Available In Germany, diamond grinding is frequently used to improve the evenness and skid resistance of concrete pavement surfaces. Since diamond grinding has been observed to affect tyre/pavement noise emission favourably, the relationship among surface texture, concrete composition and noise emission of concrete pavement surfaces has been systematically investigated. The simulation program SPERoN was used in a parameter study to investigate the main factors which affect noise emission. Based on the results of the simulations, textured concrete surfaces were produced by using a laboratory grinding machine. As well as the composition of the concrete, the thickness and spacing of the diamond blades were varied. The ability of the textured surfaces to reduce noise emission was assessed from the texture characteristics and air flow resistance of textured surfaces measured in the laboratory. It was found that concrete composition and, in particular, the spacing of the blades affected the reduction in noise emission considerably. The noise emission behaviour of numerous road sections was also considered in field investigations. The pavement surfaces had been textured by diamond grinding during the last years or decades. The results show that diamond grinding is able to provide good, durable noise-reducing properties. Several new pavement sections were investigated using thicknesses and spacings of the blades similar to those used in the laboratory to optimize noise emission reduction. It is concluded that diamond grinding is a good alternative to exposed aggregate concrete for the production of low-noise pavement surfaces.

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

    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 properties of CTMiGr and the deformation characteristics relevant to shrinkage crack susceptibility were evaluated. The main aim of this research is to develop models which allow the structural prop...

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

    Ismail Sallehan; Ramli Mahyuddin

    2016-01-01

    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 enhanc...

  19. Behaviour of steel tubular stub and slender columns filled with concrete using recycled aggregates

    E K Mohanraj; Kandasamy, S.; Malathy, R

    2011-01-01

    This paper is based on a study that was done by utilising construction and demolition debris that had been effectively recycled, in structural members. The steel tubular columns were filled with different types of waste material, as well as recycled aggregate concrete, instead of normal conventional concrete. The results were subsequently analysed. The behaviour of circular and square concrete-filled steel tubular sections (CFSTs) under axial load, in which coarse aggregate had been partially...

  20. Utilization of Six Sigma in Quality Improvement of Recycled Aggregates Concrete

    Mohamad Terro; Moetaz El-Hawary; Rana Al-Fares; Mark Goldstein

    2013-01-01

    The use of recycled demolished concrete in producing new concrete is an established method to improve sustainability through reducing the environmental impact of using virgin aggregates and through reducing construction waste. Six sigma is a set of tools and strategies for process improvement. In this paper, the six sigma DMAIC methodology is utilized to optimize the design parameters in order to improve and assure the quality of the resulting recycled aggregate concrete. The project aims to ...

  1. Cellular Concrete Bricks with Recycled Expanded Polystyrene Aggregate

    Juan Bosco Hernández-Zaragoza

    2013-01-01

    Full Text Available Cellular concrete bricks were obtained by using a lightweight mortar with recycled expanded polystyrene aggregate instead of sandy materials. After determining the block properties (absorption, compressive strength, and tensile stresses, it was found that this brick meets the requirements of the masonry standards used in Mexico. The obtained material is lighter than the commercial ones, which facilitates their rapid elaboration, quality control, and transportation. It is less permeable, which helps prevent moisture formation retaining its strength due to the greater adherence shown with dry polystyrene. It was more flexible, which makes it less vulnerable to cracking walls due to soil displacements. Furthermore, it is economical, because it uses recyclable material and has properties that prevent deterioration increasing its useful life. We recommend the use of the fully dry EP under a dry environment to obtain the best properties of brick.

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

    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 241Am-Be neutron source. The results show that the peridotite is an excellent neutron shielding material

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

    FAREED AHMED MEMON; NAFEES AHMED MEMON; RIZWAN ALI MEMON

    2010-01-01

    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-s...

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

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

    2016-01-01

    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. ...

  5. Brittleness Generation Mechanism and Failure Model of High Strength Lightweight Aggregate Concrete

    2006-01-01

    The brittleness generation mechanism of high strength lightweight aggregate concrete(HSLWAC) was presented, and it was indicated that lightweight aggregate was the vulnerable spot,initiating brittleness. Based on the analysis of the brittleness failure by the load-deflection curve, the brittleness presented by HSLWAC was more prominent compared with ordinary lightweight aggregate concrete of the same strength grade. The model of brittleness failure was also established.

  6. Microstructure and Mechanical Properties of Recycled Aggregate Concrete in Seawater Environment

    Pengjun Yue; Zhuoying Tan; Zhiying Guo

    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 th...

  7. Performance of Bridge Decks and Girders with Lightweight Aggregate Concrete, v. 2 of 2

    Ramirez, J.A.; Olek, J.; Rolle, Eric Joseph; Malone, Brian Joseph

    2000-01-01

    Structural lightweight concrete is a very versatile material and Haydite and Minergy lightweight aggregates can be utilized in the mixture development of concrete for use in girders and decks in bridges. More widespread use of lightweight aggregates (LWA) would result in savings in construction cost due to considerable dead load reduction. The materials phase of this research study evaluated the fresh concrete properties (slump, unit weight, and air content), the mechanical properties of ...

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

    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.

  9. Computational investigation of the neutron shielding and activation characteristics of borated concrete with polyethylene aggregate

    This paper presents the result of a computational study to investigate the neutron shielding and activation characteristics of concretes containing boron carbide and polyethylene. Various mixes were considered with changes in the contents of boron carbide and polyethylene aggregate. The Monte Carlo simulation code MCNP-5 was utilized to determine the transmission of neutron through concrete at different energies from 0.1 eV to 1 MeV, and ORIGEN-S code was then used to predict activation characteristics of the concretes. It was shown that the replacement of polyethylene in borated concrete greatly enhanced the shielding efficiency of the concrete, and total activity levels of the concrete were considerably decreased with this replacement. Furthermore, double-layered structures having the first layer of polyethylene aggregate-replaced concrete and the second layer of 2 wt% borated concrete are shown to improve shielding efficiency more significantly than monolithic structures

  10. Computational investigation of the neutron shielding and activation characteristics of borated concrete with polyethylene aggregate

    Park, S.J.; Jang, J.G.; Lee, H.K., E-mail: leeh@kaist.ac.kr

    2014-09-15

    This paper presents the result of a computational study to investigate the neutron shielding and activation characteristics of concretes containing boron carbide and polyethylene. Various mixes were considered with changes in the contents of boron carbide and polyethylene aggregate. The Monte Carlo simulation code MCNP-5 was utilized to determine the transmission of neutron through concrete at different energies from 0.1 eV to 1 MeV, and ORIGEN-S code was then used to predict activation characteristics of the concretes. It was shown that the replacement of polyethylene in borated concrete greatly enhanced the shielding efficiency of the concrete, and total activity levels of the concrete were considerably decreased with this replacement. Furthermore, double-layered structures having the first layer of polyethylene aggregate-replaced concrete and the second layer of 2 wt% borated concrete are shown to improve shielding efficiency more significantly than monolithic structures.

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

    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. PMID:19540649

  12. Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties

    Neeraj Jain

    2015-01-01

    Full Text Available Present investigations deal with the development of green concrete (M 30 grade using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100% with recycled coarse aggregate on various mechanical and durability properties of hardened concrete were discussed and compared with controls at different w/c ratio. Improvements in all the engineering properties of hardened concrete were observed using washed recycled coarse aggregates. The compressive strength of 28-day hardened concrete containing 100% washed recycled aggregate was slightly lower (7% than concrete prepared with natural aggregates. Water absorption, carbonation, and rapid chloride penetration test were conducted to assess the durability of the concrete. Concrete was found moderately permeable for chloride ions penetration and no carbonation was observed in all the concrete mixes studied.

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

    Abdelfatah, Akmal S.; Tabsh, Sami W.

    2011-01-01

    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 impl...

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

    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.

  15. 粉煤灰对轻骨料混凝土抗硫酸盐腐蚀的影响%Influences of fly ash on the resistance of lightweight aggregate concrete to sulphate attack

    焦楚杰; 余其俊

    2014-01-01

    Durability experiments of lightweight aggregate concrete under interaction of double factors were conducted ,and the factors were sulphate attack and soaking-drying circulation.The research results showed that the general trend of performances of lightweight aggregate concrete attenuate with time,and there was a positive relationship between the concentration of the sulphate solution and the corrosion degree to the lightweight aggregate concrete.Other being equal,the coefficient of strength resistance corrosion and the relative dynamic elastic modulus of lightweight aggregate concrete improve with the increasing of the amount of fly ash ,and the turning point of the both two properties from increment to reduction occured when the amount of fly ash was 40%.%进行了硫酸钠溶液腐蚀与浸烘循环的双因素共同作用下轻骨料混凝土耐久性试验,研究结果表明:在腐蚀环境中,轻骨料混凝土性能的总体趋势随时间推移而衰减,溶液浓度与腐蚀的力度成正向关系。在其他条件相同的情况下,随着粉煤灰掺量的增加,混凝土强度耐蚀系数和相对动弹性模量逐渐提高,在粉煤灰掺量为40%时,出现从增至减的转折点。

  16. Property of super lightweight concrete using expanded polystyrene beads as coarse aggregate; Happo polystyrene beads wo mochiita chokeiryo concrete no kyodo seijo

    Matsuo, E. [Yamaguchi University, Yamaguchi (Japan). Faculty of Engineering; Matsushita, H. [Kyushu University, Fukuoka (Japan). Faculty of Engineering; Makizumi, T. [Kyushu Kyoritsu University, Fukuoka (Japan)

    1997-08-20

    For drastic weight reduction of concrete, the compressive strength and drying shrinkage of super lightweight concrete were studied using expanded polystyrene beads (EPSB) of 0.02 or less in specific gravity as coarse aggregate. The drying shrinkage strain of lightweight concrete mixed with EPSB increases to 1.6-2 times that with normal aggregate, however, it decreases to the same level as normal concrete by using a shrinkage-reducing agent. EPSB makes it possible to produce super lightweight concrete of 0.8 in specific gravity. Although the specific strength increases by using artificial lightweight fine aggregate, the effect of fine aggregate on the specific strength decreases with an increase in EPSB. The compressive strength of EPSB concrete increases along a concave curve with the specific gravity. The specific gravity is proportional to a static elastic modulus. Chopped fiber reinforcement largely improves not only the bending strength but also the compressive strength. The reinforcement is derived from a fine crack dispersion effect and mortar crack growth control effect. 15 refs., 31 figs., 6 tabs.

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

    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.

  18. DSP强化与预处理的再生骨料混凝土强度及破坏机理分析%STRENGTH AND FAILURE MECHANISM ANALYSIS OF RECYCLED AGGREGATE CONCRETE IMPROVED BY DSP GROUT

    张学兵; 方志; 郭雪怡; 徐晓伟; 唐卓; 樊萱; 匡成钢

    2012-01-01

    The strength of recycled concrete was studied whose recycled coarse aggregate was preprocessed by DSP grout.At the same time,the strength of recycled concrete added DSP grout as part of the concrete directly in the mixing process was also studied,but also with a comparison of the basic recycled concrete.The results show that for the cube compressive strength and prism compressive strength,the strength of recycled concrete improved by DSP grout is the highest,respectively,increased by 25.6%(or 26.7%) as compared to the prism compressive strength of the basic recycled concrete.And for DSP grout pretreatment recycled aggregate concrete,7 d cube compressive strength is higher than the basic recycled concrete,28 d cube compressive strength is lower than the basic recycled concrete,28d prism compressive strength is high and low.In addition,the failure mechanism of the recycled concrete is analyzed.%研究DSP浆液预处理再生骨料混凝土的强度和直接在组分中加入DSP浆液强化再生混凝土的强度,并与基准再生混凝土进行对比。试验结果表明,无论是立方体抗压强度,还是棱柱体抗压强度,DSP浆液强化再生混凝土的强度均为最高,比基准再生混凝土棱柱体强度提高25.6%(或26.7%);而对于DSP浆液预处理再生骨料混凝土,7 d立方体抗压强度高于基准再生混凝土,28 d立方体抗压强度则低于基准再生混凝土,28 d棱柱体抗压强度则各有高低。并对再生混凝土的破坏机理进行了分析。

  19. Lightweight Aggregate Concrete Beams. Load-bearing Capacity

    Larsen, Henning; Goltermann, Per; Ingholt, N.U.

    1997-01-01

    This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity.......This paper deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents formulas for the moment capacity as well as the shear force capacity....

  20. Lightweight Aggregate Concrete Components. Load-bearing Capacity

    Larsen, Henning; Ingholt, N.U.; Goltermann, Per

    1996-01-01

    The project presented here deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents expressions for the moment capacity as well as the shear force capacity......The project presented here deals with the load-bearing capacity of reinforced beams made of lightweight aggregate concrete with open structure and documents expressions for the moment capacity as well as the shear force capacity...

  1. 应用固定砂石总体积法配制大粒径自密实混凝土%Preparation of self-compacting concrete with large diameter aggregate by fixed total volume of sand and gravel

    危加阳; 罗竹容

    2014-01-01

    The method of fixed volume of sand and gravel is commonly used in mixture proportion design of self-compacting concrete. In order to return to the natural properties of aggregate, the method of fixed total volume of sand and gravel that is dif-ferent from the traditional concept is proposed, i. e. , in the mixture proportion design of self-compacting concrete, we should ensure it completely enwrapped, separated and suspended by cementing material. Moreover, this method is also applied in the preparation of self-compacting concrete with the maximum size of 31. 5 mm of coarse aggregate. The practices show that the self-compacting concrete still has good stability of anti-segregation and demonstrates that the preparation of self-compacting con-crete with large diameter aggregate by fixed total volume of sand and gravel is feasible.%固定砂石体积法是设计自密实混凝土配合比的常用方法。为回归骨料的天然属性,提出了有别于传统概念的固定砂石总体积法,即在配制自密实混凝土时,按胶凝材料浆包裹、分隔、悬浮总骨料为目标进行配比计算。同时,在工程实际中,利用该方法尝试将最大粒径为31.5 mm且具有较好抗离析稳定性的粗骨料用于自密实混凝土配制。实践证明,利用固定砂石总体积法配制较大粒径骨料自密实混凝土是可行的。

  2. Rio 2016 sustainable construction commitments lead to new developments in recycled aggregate concrete

    Toledo Filho, R.D.; Koenders, E.A.B.; Pepe, M.; Cordeiro, G.C.; Fairbairn, E.; Martinelli, E.

    2013-01-01

    The Brazilian construction industry is committed to delivering the venues and infrastructure of the Rio 2016 Olympic and Paralympic Games with zero increase in carbon dioxide emissions, reduced consumption of raw materials, increased use of renewable materials and 100% local recycling of constructio

  3. Oil Palm Fiber as Partial Replacement Aggregates for Normal Concrete

    1Wasiu John,

    2015-09-01

    Full Text Available This study is focused on assessing the effectiveness of palm kernel shell (PKS as partial replacement aggregates for normal concrete. The tests carried out on PKS concrete at a constant water cement ratio of 0.5 with mix ratios 1:2:4 and 1:1 : 3 with PKS varied from 0%-30%. The results of the slump and compaction factor test showed that all mixes were workable for all replacement levels considered. The compressive strength values obtained ranges between 32.2N/mm2 - 13.4N/mm2 with implies that, the addition of PKS in the production of light weight concrete is suitable for both mix ratios. The cost analysis also revealed reduction in cost by 6.5%, 13% and 19.5% for PKS replacement at 10%, 20% and 30% respectively. It is concluded that PKS is effective, less expensive as partial replacement aggregates and also reduces environmental pollution.

  4. Feasibility Study of Applying Recycled Aggregate from Building Debris in Concrete

    PENG Yuzhu

    2011-01-01

    Coarse and fine aggregate constitutes an average of approximately 55% to 80% of the total volume of concrete materials.Concrete remains the most commonly-used building material worldwide.As a result,the massive use of aggregate will have a direct impact on the earth's natural resources if an appropriate replacement material is not found,violating the spirit of sustainable development.This study makes a preliminary examination of using coarse and fine aggregate produced from discarded construction materials in concrete.Results indicate that the compressive strength of densified mixture concrete at 28 days can reach 56.88MPa( recycled materials used as coarse aggregate,and natural sand used as fine aggregate)and 53.33 MPa (recycled materials used as both coarse and fine aggregate).While this type of material is not yet fully understood,further research into this area should enable feasible applications in concrete.However,unsuitable mixtures have serious impact on the durability and overall economy of concrete.Pending further research on suitable mixture designs,a complete application of recycled aggregate in concrete can be expected.

  5. 再生骨料特性对再生混凝土强度和碳化性能的影响%Influence of Recycled Aggregate on Strength and Anti-carbonation Properties of Recycled Aggregate Concrete

    崔正龙; 路沙沙; 汪振双

    2012-01-01

    Influence of surface mortar strength and adhesive rate around coarse aggregate on recycled aggregate concrete(RAC) were investigated. Concrete of different strength were prepared with recycled aggregate of different surface mortar strength and adhesive rate to investigate their properties. It has been shown that, for low strength recycled aggregate concrete with higher strength ordinary concrete, the strength of recycled aggregate concrete and ordinary concrete are nearly the same, and the effect of surface mortar strength and adhesive rate around coarse aggregate on recycled aggregate concrete is low, while the carbonization depth of recycled aggregate concrete is higher than that of ordinary concrete; on the other hand, for recycled aggregate concrete prepared by low strength ordinary concrete, there are great differences between recycled aggregate concrete and ordinary concrete, the effect of surface mortar strength and adhesive rate around coarse aggregate on recycled aggregate concrete is significant and carbonization depth is increasing.%为了评价再生骨料表面砂浆的强度及附着率对再生混凝土性能的影响,以再生骨科表面不同的砂浆强度及附着率为变量,配制了不同强度等级的再生骨料混凝土,通过对比性强度试验和碳化试验评价了再生混凝土内部存在的2个界面过渡区与混凝土性能的关系.结果表明:以高强度原生混凝土为再生骨料配制相对较低强度等级的再生骨料混凝土时,其强度与普通混凝土几乎相同,再生骨料表面砂浆的强度及附着率对再生骨料混凝土强度影响不大,但碳化深度有所增大;以相对较低强度原生混凝土为再生骨料配制同强度等级以上的再生骨科混凝土时,其强度与普通混凝土相差较大,再生骨料表面砂浆的强度及附着率对再生混凝土强度影响较大,碳化深度也相应增大.

  6. Estimation of Concrete's Porosity by Ultrasounds

    Benouis, A.; Grini, A.

    Durability of concrete depends strongly on porosity; this conditions the intensity of the interactions of the concrete with the aggressive agents. The pores inside the concrete facilitate the process of damage, which is generally initiated on the surface. The most used measurement is undoubtedly the measurement of porosity accessible to water. The porosimetry by intrusion with mercury constitutes a tool for investigation of the mesoporosity. The relationship between concrete mixtures, porosity and ultrasonic velocity of concrete samples measured by ultrasonic NDT is investigated. This experimental study is interested in the relations between the ultrasonic velocity measured by transducers of 7.5 mm and 49.5 mm diameter and with 54 kHz frequency. Concrete specimens (160 mm diameter and 320 mm height) are fabricated with concrete of seven different mixtures (various W/C and S/S + G ratios), which gave porosities varying between 7% and 16%. Ultrasonic velocities in concrete were measured in longitudinal direction. Finally the results showed the influence of ratio W/C, where the porosity of the concretes of a ratio W/C _0,5 have correctly estimated by ultrasonic velocity. The integration of the concretes of a lower ratio, in this relation, caused a great dispersion. Porosity estimation of concretes with a ratio W/C lower than 0,5 became specific to each ratio.

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

    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.

  8. Radiation shielding properties of concrete with electric arc furnace slag aggregates and steel shots

    Highlights: ► Industrial waste products were used to produce radiation shielding concrete. ► The mechanical and radiation shielding properties were evaluated. ► The developed concrete is cheaper and conserves the natural resources. - Abstract: Heavyweight concrete, prepared with a mixture of concrete and heavyweight aggregates or metallic components, is generally used for radiation shielding purposes. In the present study the radiation shielding properties of concrete prepared with electric arc furnace slag aggregates (EAFSAs) and steel shots, was investigated. The results indicated that concrete mixed with 50% EAFSA and 50% steel shots meets the weight and radiation requirements. The use of 50% EAFSA results in a decrease in the cost of concrete and also conserves a useful material, such as iron ore

  9. The effect of blast furnace slag on the self-compactability of pumice aggregate lightweight concrete

    Murat Kurt; Türkay Kotan; Muhammed Said Gül; Rüstem Gül; Abdulkadir Cüneyt Aydin

    2016-02-01

    This paper presents the results of an experimental study of the effects of blast furnace slag, different water/(cement+mineral additive) ratios and pumice aggregates on some physical and mechanical properties of self-compacting lightweight aggregate concrete. In this study, pumice was used as lightweight aggregate. Several properties of self-compacting pumice aggregate lightweight concretes, such as unit weight, flow diameter, T50 time, flow diameter after an hour, V-funnel time, and L-box tests, 7, 28, 90 and 180-day compressive strength, 28-day splitting tensile strength, dry unit weight, water absorption, thermal conductivity and ultrasonic pulse velocity tests, were conducted. For this purpose, 18 series of concrete samples were prepared in two groups. In the first group, pumice aggregate at 100% replacement of natural aggregate was used in the production of self-compacting lightweight aggregate concrete with constant w/(c+m) ratios as 0.35, 0.40, and 0.45 by weight. Furthermore, as a second group, pumice aggregate was used as a replacement of natural aggregate, at the levels of 0, 20, 40, 60, 80, and 100% by volume. Flow diameters, T50 times, paste volumes, 28-day compressive strengths, dry unit weights, thermal conductivities and ultrasonic pulse velocity of self-compacting lightweight aggregate concrete were obtained over the range of 600–770 mm, 3–9 s, 435–540 l/m3, 10.6–65.0 MPa, 845–2278 kg/m3, 0.363–1.694 W/mK and 2617–4770 m/s respectively, which satisfies not only the strength requirement of semistructural lightweight concrete but also the flowing ability requirements and thermal conductivity requirements of self-compacting lightweight aggregate concrete.

  10. Influence of Polymer Addition on Performance and Mechanical Properties of Lightweight Aggregate Concrete

    Jiang Cong-sheng; Wang Tao; Ding Qing-jun; Huang Shao-long; Wang Fa-zhou; Geng Jian; Hu Shu-guang

    2004-01-01

    The influence of polymer addition on microstructure, performance and mechanical properties of lightweight aggregate concrete was investigated. It was found that the addition of polymer improved the performance and mechanical properties of lightweight aggregate concrete. It was asccrtaincd thai the modification of microstructural uniformity and dcnsification with the addition of polymer is responsible for the enhancement of mechanical properties.With respect to compressive strength and bending strcngth, the lightweight aggregate concrete added with 13% ethylene-acetate ethylene interpolymer (EVA) exhibits preferred mechanical properties.

  11. Exploratory Study of Palm Oil Fuel Ash as Partial Cement Replacement in Oil Palm Shell Lightweight Aggregate Concrete

    K. Muthusamy

    2014-07-01

    Full Text Available In Malaysia, issue of environmental pollution resulting from disposal of Palm Oil Fuel Ash (POFA which is a by-product from palm oil mill has initiated research to incorporate this waste in Oil Palm Shell (OPS lightweight aggregate concrete production. The current study investigates the effect of palm oil fuel ash content as partial cement replacement towards compressive strength OPS lightweight aggregate concrete. Several OPS lightweight aggregate concrete mixes were produced by replacing various percentage of POFA ranging from 10, 20, 30, 40 and 50%, respectively by weight of cement. All the mixes were cast in form of cubes and then subjected to water curing until the testing date. The compressive strength test is conducted in accordance to BSEN 12390 (2009 at 7 and 28 days. From the results, it was observed that the combination of appropriate POFA content would enhance the compressive strength of OPS lightweight aggregate concrete. Specimen produced using 20% POFA as partial cement replacement exhibit higher value of compressive strength than that of control OPS lightweight aggregate concrete. However, mixes consisting POFA up to 50% is also suitable for structural application.

  12. Autogenous Shrinkage of High Strength Lightweight Aggregate Concrete

    DING Qingjun; TIAN Yaogang; WANG Fazhou; ZHANG Feng; HU Shuguang

    2005-01-01

    The characteristic of autogenous shrinkage ( AS ) and its effect on high strength lightweight aggregate concrete (HSLAC) were studied. The experimental results show that the main shrinkage of high strength concrete is AS and the amount of cement can affect the AS of HSLAC remarkably. At the early stage the AS of HSLAC is lower than that of high strength normal concrete, but it has a large growth at the later stage. The AS of high strength normal concrete becomes stable at 90d age, but HSLAC still has a high AS growth. It is found that adjusting the volume rate of lightweight aggregate, mixing with a proper dosage of fly ash and raising the water saturation degree of lightweight aggregate can markedly reduce the AS rate of HSLAC.

  13. An experimental relationship between complete liquid saturation and violent damage in concrete submitted to high temperature

    DAL PONT, S; COLINA, H; Dupas, A; EHRLACHER, A

    2005-01-01

    This paper presents a damage mechanism for high performance concrete at high temperature. Crack opening in concrete is related to water thermal dilation: the aim of this work is to propose a low-cost method for verifying, for a given concrete formulation, this damage mechanism and, at least, warn against spalling risk. Concrete specimens (discs of diameter 150 mm and 50 mm thickness) were heated on one face up to a temperature of about 280°C. The temperature and gas pressure fields were const...

  14. RELATIONSHIPS BETWEEN SOIL MICROBIAL BIOMASS, AGGREGATE STABILITY AND AGGREGATE ASSOCIATED-C: A MECHANISTIC APPROACH

    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.

  15. The Next Generation Ecological Self Compacting Concrete with Glass Waste Powder as a Cement Component in Concrete and Recycled Concrete Aggregates

    Kara, P

    2013-01-01

    In the present study the performance characteristics (workability, compressive strength, frost resistance, permeability and temperature of hydration) of the ecological self compacting concrete with reduced cement content and with the next generation recycled concrete aggregates which are obtained from crashed concrete specimens with cement substitution at level of 30% with waste glass powder were investigated. Waste glass as powder ground to certain fineness accelerates beneficial chemical re...

  16. 利用预处理法制备高强轻骨料混凝土的研究%Research on appIying pretreatment to prepare high-strength Iightweight aggregate concrete

    麻建锁; 元敬顺; 闫杰; 张巧伟; 温小凯

    2015-01-01

    To obtain lightweight aggregate concrete with good workability and high strength,measures such as pre-treatment and mix-ing with mineral admixtures were applied to prepare high-strength lightweight aggregate concrete. According to characteristics of mineral admixture,the mix proportion of gravel-type lightweight aggregate concrete was designed and the effect of the pretreating aggregate method on workability and strength of concrete was compared in the test. Then,the measures optimized in formulation design and process were taken to prepare sphere-type high-strength lightweight aggregate concrete. The test results show that the pretreating aggre-gate method can improve the workability and compressive strength of concrete mixture. The mix proportion of cement,coal ash,silica fume,lightweight aggregate,sand and water is 350:150:50:530:577:168.The dosage of water-reducing agent is 0.85%.The slump of gravel-type lightweight aggregate concrete prepared by pretreatment method reaches 270 mm.The loss amount after one hour is 0mm.No segregation or bleeding occurs in the mixture,and there is no flotation of lightweight aggregate. The dry apparent density of lightweight concrete is less than 1 740 kg/m3 ,and the 28d compressive strength reaches 52.6 MPa.%为了得到和易性好、强度高的轻骨料混凝土,采用预处理法、掺加矿物掺合料等措施,制备高强轻骨料混凝土。试验根据矿物掺合料的特性,设计了碎石型轻骨料混凝土的配合比,对比了预处理骨料方法对混凝土和易性和强度的影响。试验结果表明:预处理骨料方法可以提高混凝土拌合物的和易性和抗压强度。配合比为水泥:粉煤灰:硅灰:轻骨料:砂:水=300:187.5:75:554:540:182,减水剂掺量0.85%,采用预处理法制备的碎石型轻骨料混凝土坍落度达270 mm,1 h经时损失量为0 mm,拌合物无离析、泌水、轻骨料无上浮现象,轻骨料

  17. Green Concrete from Sustainable Recycled Coarse Aggregates: Mechanical and Durability Properties

    Neeraj Jain; Mridul Garg; Minocha, A. K.

    2015-01-01

    Present investigations deal with the development of green concrete (M 30 grade) using recycled coarse aggregates for sustainable development. Characterization of recycled coarse aggregates showed that physical and mechanical properties are of inferior quality and improvement in properties was observed after washing due to removal of old weak mortar adhered on its surface. The influence of natural coarse aggregates replacement (50 and 100%) with recycled coarse aggregate on various mechanical ...

  18. Experimental Research on High Temperature Resistance of Modified Lightweight Concrete after Exposure to Elevated Temperatures

    Ke-cheng He; Rong-xin Guo; Qian-min Ma; Feng Yan; Zhi-wei Lin; Yan-Lin Sun

    2016-01-01

    In order to improve the spalling resistance of lightweight aggregate concrete at high temperature, two types of modified materials were used to modify clay ceramsite lightweight aggregates by adopting the surface coating modification method. Spalling of the concrete specimens manufactured by using the modified aggregates was observed during a temperature elevation. Mass loss and residual axial compressive strength of the modified concrete specimens after exposure to elevated temperatures were...

  19. Characterization of High Density Concrete by Ultrasonic Goniometer

    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)

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

    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.

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

    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

  2. Fracture resistance on aggregate bridging crack in concrete

    ZHANG Xiufang; XU Shilang

    2007-01-01

    Fracture toughening exhibited in quasi-brittle materials such as concrete is often mainly related to the action of aggregate bridging,which leads to the presence of a fracture process zone ahead of stress-free cracks in such materials.In this investigation,the fracture resistance induced by aggregate bridging,denoted by GI-bridging,is the primary focus.In order to quantitatively determine it,a general analytical formula is firstly developed,based on the definition of fracture energy by Hillerborg.After this,we further present the calculated procedures of determining this fracture resistance from the recorded load vs.crack opening displacement curve.Then,both numerical simulations and fracture experiments are performed on concrete three-point bending beams.Utilizing the obtained load against crack opening displacement curve,the value of GI-bridging at any crack extension as well as the change of GI-bridging with the crack extension is examined.It is found that GI-bridging will firstly increase with the development of crack and then stay constant once the initial crack tip opening displacement reaches the characteristic crack opening displacement w0.The effects of material strength and specimen depth on this fracture resistance are also investigated.The results reveal that the values of GI-bridging of different specimens at any crack propagation are strongly associated with the values of fracture energy of specimens.If the values of fracture energy between different specimens are comparable,the differences between GI-bridging are ignored.Instead,if values of fracture energy are different,the GI-bridging will be different.This shows that for specimens with different strengths,GI-bridging will change greatly whereas for specimens that are different in depth,whether GI-bridging exhibits size effect depends on whether the fracture energy of specimens considered in the calculation of GI-bridging is assumed to be a size-dependent material parameter.

  3. Evolution of pyrrhotite oxidation in aggregates for concrete

    Oliveira, I.

    2014-12-01

    Full Text Available Rocks containing pyrrhotite bands are sometimes used to produce concrete. These rocks oxidize and produce long-term expansive reactions that damage concrete structures, leading to important economic and risk related repercussions. The present study analyses several aspects that affect the oxidation process of the aggregate such as the existence of preferential paths for the entrance of the oxidizing agent and the conversion process of the chemical elements involved in the reaction. For that, host rock samples containing pyrrhotite were investigated by scanning electron microscopy and energy dispersive spectroscopy. The results shows that the pyrrhotite appears in bands that create planes of weakness and present cracks that serve as preferential paths for the entrance of oxygen. Furthermore, a new representation is proposed for the oxidation process.Rocas con bandas de pirrotina han sido usadas para producir áridos destinados a la fabricación de hormigones. Las mismas son susceptible a un fenómeno de oxidación que a largo plazo produce la degradación del material, llevando a importantes repercusiones económica y en cuanto a la seguridad. El presente estudio evalúa la influencia de diferentes aspectos que pueden afectar dicho proceso de oxidación del agregado, tales como la existencia de caminos preferentes para la entrada del agente oxidante y los elementos químicos involucrados en la reacción. Para ello, muestras de roca con pirrotina han sido analizadas mediante microscopía electrónica de barrido. Los resultados indican que la pirrotina aparece en bandas que dan lugar a planos de debilidad y fisuración. Esas fisuras actúan como caminos preferentes a la entrada del oxígeno. Asimismo, con base en los análisis realizados se ha propuesto una nueva representación para el proceso de oxidación.

  4. Research on the relationship between water stability and aggregate gradation of asphalt pavement

    Zhao Bing; Zhao Bo

    2015-01-01

    In the early destruction of asphalt pavement, water damage is the most major form.In this paper, experimental study was conducted on the composition of asphalt concrete,Marshall specimens were made in different types of aggregate gradation with the same kind of asphalt. Water immersion tests were conducted in order to analysis the relationship between the water stability and aggregate gradation of asphalt pavement.

  5. STUDY ON DURABILITY PROPERTIES OF RECYCLED AGGREGATE CONCRETE INCORPORATED WITH S ILICA FUME AND MINERAL QUARTZ

    Anand K . Darji *; Dr. Indrajit N Patel,; Mrs. Jagruti Shah

    2015-01-01

    Disposal of construction waste is now new challenge for the construction industry in this era. This is peak time to use Construction waste as recycled aggregate (RA) in concrete manufacturing for sustainable development. Recycled aggregate concrete (RAC ) is the future to save environment from the waste. Supplementary Cementing Materials (SCMs) are widely used these days to improve the durability of c oncrete. Silica fume has gai...

  6. Strength and Durability Study on Recycled Aggregate Concrete Using Glass Powder

    Priscilla M; Asst Prof. Pushparaj A Naik

    2014-01-01

    Waste glass powder was used as secondary cementitious material towards production of recycled aggregate concrete with improved strength and durability attributes. Experimental investigation of using waste glass powder, as partial replacement for cement, to overcome the drawbacks of recycled aggregate and the resulting concrete showed that waste glass, when milled to micro-scale particle size, is estimated to undergo pozzolanic reactions with cement hydrates, forming secondary calcium silicate...

  7. Effect of Lightweight Aggregate Pre-wetting on Micro-structure and Permeability of Mixed Aggregate Concrete

    GE Yong; KONG Lijuan; ZHANG Baosheng; YUAN Jie

    2009-01-01

    The influence of lightweight aggregate(LWA)pre-wetting on the chemical bound water and pore structure of the paste around aggregate as well as concrete permeability were investi-gated.The results show that,in early age the dry LWA has significant effect on the formation of dense paste around it and improving the concrete impermeability.However the prewetted LWA has strong water-releasing effect in later age,which increases the hydration degree of the paste around it, and makes the adjacent paste develop a structure with low porosity and finer aperture,furthermore the concrete impermeability can be improved.It is suggested that,as for concrete with low durability requirement,the LWA without pre-wetting treatment can be used as long as meet the workability re-quirement of fresh concrete,the good impermeability of concrete can be gained as well.As for con-crete with high durability requirement,the prewetted LWA should be used,and the pre-wetting time should be extended as long as possible,in order to optimize the concrete structure in long term,and improve the concrete durability.

  8. Pore Structure and Influence of Recycled Aggregate Concrete on Drying Shrinkage

    Yuanchen Guo; Jueshi Qian; Xue Wang

    2013-01-01

    Pore structure plays an important role in the drying shrinkage of recycled aggregate concrete (RAC). High-precision mercury intrusion and water evaporation were utilized to study the pore structure of RAC, which has a different replacement rate of recycled concrete aggregate (RCA), and to analyze its influence on drying shrinkage. Finally, a fractal-dimension calculation model was established based on the principles of mercury intrusion and fractal-geometry theory. Calculations were performed...

  9. INVESTIGATION ON MECHANICAL PROPERTIES OF STRUCTURAL LIGHTWEIGHT CONCRETE MADE WITH PUMICE AGGREGATE

    Selçuk TÜRKEL; Bimen KADİROĞLU

    2007-01-01

    In this study, structural lightweight concrete mixtures are produced by using Kayseri pumice aggregate. The other constituent materials used in producing the lightweight concrete mixtures are; CEM I 42.5 cement as binder, silica fume and fly ash as mineral admixtures. The following properties are determined; slump, unit weight and air content of fresh mix, as well as unit weight, compressive strength, splitting tensile strength and flexural strength of hardened concrete. Test results show tha...

  10. Impact load-induced microstructural damage of concrete made with unconventional aggregates

    Erdem, Savas

    2012-01-01

    Understanding the correlation between the mix proportions, micro structural characteristics, and macro-scale properties of concrete (i.e. the process-structure-properties relationship) is fundamental to achieving a more advanced understanding of how to apply and optimise this abundant engineering material. Although, concrete has been traditionally evaluated by its physico-mechanical and functional properties; development of advanced and effective inspection techniques during the last decade h...

  11. A kinetic approach to the sequence–aggregation relationship in disease-related protein assembly

    Barz, Bogdan; Wales, David J.; Strodel, Birgit

    2014-01-01

    It is generally accepted that oligomers of aggregating proteins play an important role in the onset of neurodegenerative diseases. While in silico aggregation studies of full length amyloidogenic proteins are computationally expensive, the assembly of short protein fragments derived from these proteins with similar aggregating properties has been extensively studied. In the present work molecular dynamics simulations are performed to follow peptide aggregation on the microsecond time scale. B...

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

    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.

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

    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. PMID:26700727

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

    Mehmet Gesoglu; Erhan Güneyisi; Hatice Öznur Öz; Mehmet Taner Yasemin; Ihsan Taha

    2015-01-01

    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%. Durabi...

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

    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. The Application of Equivalent Age Concept to Sand Concrete Compared to Ordinary Concrete

    Nabil Bella

    2016-01-01

    Full Text Available In this research the equivalent age concept was used, in order to simulate strength development of heat treated sand concrete compared with ordinary concrete at different temperature, 35, 55, and 70°C, and validate the simulation results with our experimental results. Sand concrete is a concrete with a lower or without coarse aggregate dosage; it is used to realize thin element as small precast prestressed beams, in injected concrete or in regions where sand is in extra quantity and the coarse aggregate in penury. This concrete is composed by principally sand, filler, superplasticizer, water, and cement. The results show that the simulation of ordinary concrete was acceptable with an error lower than 20%. But the error was considerable for the sand concrete. The error was due to large superplasticizer dosage, which modified the hardening of sand concrete; the most influent parameter in Arrhenius law is apparent energy activation, to search for the value of the activation energy which gives the best simulation; a superposition is used of two curves of different temperature and with superplasticizer dosage 4% and several values of activation energy, 15, 20, 25, and 30 × 10 kcal. The simulation becomes ameliorated with the adequate value of activation energy.

  17. Effects of Hybrid Polypropylene-Steel Fiber Addition on Some Hardened Properties of Lightweight Concrete with Pumice Breccia Aggregate

    Slamet Widodo; Iman Satyarno; Sri Tudjono

    2012-01-01

    Lightweight concrete application in construction field is growing rapidly in these recent years due to its advantages over ordinary concrete. In this paper, pumice breccia which can be found abundantly in Indonesia is proposed to be utilized as the coarse aggregate. In spite of its benefits, lightweight concrete exhibits more brittle characteristics and lower tensile strength compared with normal concrete. On the other hand, fiber addition into concrete has become widely used to improve its t...

  18. Effect of Pre-wetted Light-weight Aggregate on Internal Relative Humidity and Autogenous Shrinkage of Concrete

    2006-01-01

    This research indicates that the gradient of internal relative humidity (IRH) decreases rapidly within 7-day curing age in HPC.The amount of water imported by pre-wetted light-weight aggregate can regulate IRH of concrete.By importing a proper amount of water, the process of the decline of IRH can be delayed and the antogenous shrinkage can be reduced.The relationship among the amount of water imported by pre- wetted lightweight aggregate, IRH and AS was established.The result provides a new method of reducing early AS and enhancing early cracking resistance of HPC.

  19. Characteristics of airborne gold aggregates generated by spark discharge and high temperature evaporation furnace: Mass-mobility relationship and surface area

    Svensson, Christian; Ludvigsson, Linus; Meuller, Bengt; Eggersdorfer, M.L.; Deppert, Knut; Bohgard, Mats; Pagels, Joakim; Messing, Maria; Rissler, Jenny

    2015-01-01

    The properties of gas-borne aggregates are important in nano-technology and for potential health effects. Gold aggregates from three generators (one commercial and one custom built spark discharge generator and one high-temperature furnace) have been characterized. The aggregate surface areas were determined using five approaches - based on aggregation theory and/or measured aggregate properties. The characterization included mass-mobility relationships, effective densities (assessed by an Ae...

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

    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.

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

    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.

  2. Compressive and splitting tensile strength of autoclaved aerated concrete (AAC containing perlite aggregate and polypropylene fiber subjected to high temperatures

    Borvorn Israngkura Na Ayudhya

    2011-10-01

    Full Text Available This paper presents the results of an experimental study on the residual compressive and splitting tensile strength ofautoclaved aerated concrete (AAC containing perlite and polypropylene (PP fiber subjected to high temperatures. Cylinderspecimens were subjected to various temperature ranges of 100, 200, 400, 800, and 1,000°C. The mixtures were prepared withAAC cementitious materials containing perlite at 15%, 20%, and 30% sand replacement. The polypropylene fiber content of0, 0.5%, 1%, 1.5%, and 2% by volume was also added to the mixture. The results showed that the unheated compressive andsplitting tensile strength of AACs containing PP fiber were not significantly higher than those containing no PP fiber.Furthermore, the presence of PP fiber was not more effective for residual compressive strength than splitting tensile strength.The 30% perlite replacement of sand gave the highest strength. Based on the results, it can be concluded that addition ofPP fiber did not significantly promote the residual strength of AAC specimens subjected to high temperatures.

  3. Laboratory Investigation on the Strength Gaining of Brick Aggregate Concrete Using Ordinary Portland Cement and Portland Composite Cement

    Hoque M H, Numen E H, Islam N., Mohammed

    2014-05-01

    Full Text Available This study focused on the laboratory investigation of strength variation of brick aggregate concrete made with ordinary Portland cement (OPC and Portland composite cement (PCC.The investigation was conducted by testing concrete cylinder specimens at different ages of concrete with concrete mix ratios: 1:1.5:3 and 1:2:4 by volume and with water cement ratios=0.45 and 0.60. The test result reveals that at the early age, concrete composed with OPC attained larger compressive strength than the concrete made of PCC. However, in the later age concrete made with PCC achieved higher strength than OPC.

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

    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. PMID:24982946

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

    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.

  6. A Study on the Bond Behavior of Corroded Reinforced Concrete Containing Recycled Aggregates

    Haifeng Yang

    2015-01-01

    Full Text Available This paper investigated bond-slip characteristics of chloride-induced corroded reinforced concrete incorporating different levels of recycled concrete aggregates (RCA. Pullout tests were adopted to evaluate the bonding and debonding behaviors of the embedded rebar experiencing different corrosion levels. Both high- and low-strength concrete were considered. Bond-slip curves were recorded to determine the influences of rebar corrosion levels and RCA replacements on the bond strength and debonding energy of the specimens. Test results indicate that increasing rebar corrosion level gradually weakens the antisliding ability of reinforced recycled aggregate concrete (RAC except for a small level corrosion and the degradation rate of ultimate bond strength increases with a decrease of compressive strength at 0.5% rebar corrosion. The results also demonstrate that the ultimate bond strength of reinforced RAC slightly decreases with an increase of RCA replacement. However, the relative bond strength between uncorroded rebar and RAC is little affected by RCA content, while it decreases with an increase of RCA replacement in high-strength specimens after rebar corrosion. The debonding energy between deformed rebar and RAC is found decreasing with the increment of the rebar corrosion level and increasing with an increase of RAC content.

  7. Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

    Makani, A.; Vidal, T.; Pons, G.; Escadeillas, G.

    2010-06-01

    This paper examines the influence of coarse aggregate characteristics on the time-dependent deformations of High Performances Concretes (HPC). Four concretes made using the same cement paste but incorporating different types of aggregate (rolled siliceous gravel, crushed granite, crushed limestone and crushed siliceous gravels) were studied in order to investigate the effect of aggregate properties on the compressive strength, modulus of elasticity, shrinkage and creep. The results indicate that the aggregate type has a significant effect on creep and shrinkage deformations of HPC. An influence of the shape of aggregate on time-dependent deformations has also been observed. On the basis of these results, long-term behaviour seems to be correlated to the characteristics of the Interfacial Transition Zone (ITZ) strongly depending on the mineralogical nature and properties of aggregates. The experimental results are compared with the values calculated using the current Eurocode 2 model in order to assess the accuracy of the predictions.

  8. Time-dependent behaviour of high performance concrete: influence of coarse aggregate characteristics

    Escadeillas G.

    2010-06-01

    Full Text Available This paper examines the influence of coarse aggregate characteristics on the time-dependent deformations of High Performances Concretes (HPC. Four concretes made using the same cement paste but incorporating different types of aggregate (rolled siliceous gravel, crushed granite, crushed limestone and crushed siliceous gravels were studied in order to investigate the effect of aggregate properties on the compressive strength, modulus of elasticity, shrinkage and creep. The results indicate that the aggregate type has a significant effect on creep and shrinkage deformations of HPC. An influence of the shape of aggregate on time-dependent deformations has also been observed. On the basis of these results, long-term behaviour seems to be correlated to the characteristics of the Interfacial Transition Zone (ITZ strongly depending on the mineralogical nature and properties of aggregates. The experimental results are compared with the values calculated using the current Eurocode 2 model in order to assess the accuracy of the predictions.

  9. Influence of Cementitious Materials and Aggregates Content on Compressive Strength of Palm Kernel Shell Concrete

    U.J. Alengaram; Jumaat, M. Z.; H. Mahmud

    2008-01-01

    This study reports the effect of cementitious materials, fine and coarse aggregates content on workability and compressive strength of palm kernel shell concrete. Palm kernel shells a by product of the production of palm oil, were used as lightweight aggregates. The following cementitious materials were added: 10% silica fume as additional cementitious material and 5% fly ash as cement replacement on weight of cement. The influence of varying fine aggregate and palm kernel shell content...

  10. 再生混凝土中氯离子渗透性能试验研究%Experimental Study on Chloride Ion Penetration into Recycled Aggregate Concrete

    吴相豪; 岳鹏君

    2011-01-01

    In order to investigate the effects of recycled concrete aggregate, wet and dry cycles, fly ash replacement on chloride ion penetration of recycled aggregate concrete, the chloride ion concentration in recycled aggregate concrete was measured during chloride natural diffusion test. The results show that the a-bility to resist chloride ion penetrate into recycled aggregate concrete is weaker than that for natural aggregate concrete; the resistance to chloride ion penetration into recycled aggregate concrete can be improved by replacing cement with fly ash, 20%(by mass> replacement of cement with fly ash is optimum; the rate . Of chloride ion penetration into recycled aggregate concrete under wet and dry cycles is higher than that into saturated recycled aggregate concrete.%通过氯离子自然扩散试验,测定再生混凝土试件中的氯离子浓度,分析了再生骨料、粉煤灰掺量、全浸泡与干湿循环方式对再生混凝土中氯离子渗透性能的影响.结果表明:再生混凝土抗氯离子渗透能力比普通混凝土差;掺入粉煤灰能提高再生混凝土抗氯离子渗透能力,粉煤灰最佳掺量为20%(质量分数);干湿循环方式可加快再生混凝土中氯离子的渗透速度.

  11. Environmental evaluation of green concretes versus conventional concrete by means of LCA.

    Turk, Janez; Cotič, Zvonko; Mladenovič, Ana; Šajna, Aljoša

    2015-11-01

    A number of green concrete mixes having similar basic properties were evaluated from the environmental point of view by means of the Life Cycle Assessment method, and compared with a corresponding conventional concrete mix. The investigated green concrete mixes were prepared from three different types of industrial by-products, i.e. (1) foundry sand, and (2) steel slag, both of which were used as manufactured aggregates, and (3) fly ash, which was used as a mineral admixture. Some green concrete mixes were also prepared from a recycled aggregate, which was obtained from reinforced concrete waste. In some of the green concrete mixes the recycled aggregate was used in combination with the above-mentioned types of manufactured aggregate and fly ash. All of these materials are able, to some extent, to replace natural aggregate or Portland cement in concrete mixes, thus providing an environmental benefit from the point of view of the saving of natural resources. Taking into account consequential modelling, the credit related to the avoidance of the need to dispose of the waste materials is considered as a benefit. In case of the recycling of waste concrete into aggregate, credit is attributed to the recovery of scrap iron from the steel reinforcement. In the case of the use of steel slag, credit is attributed to the recovery of metals, which are extracted from the slag before being used as an alternative material. The disadvantage of using alternative materials and recycled aggregates can sometimes be their relatively long delivery distance. For this reason, a transport sensitivity analysis was carried out. The results indicate that the use of the discussed alternative and recycled materials is beneficial in the concrete production industry. Preference is given to the fly ash and foundry sand scenarios, and especially to those scenarios which are based on the combined use of recycled aggregate with these two alternative materials. It was found that longer delivery

  12. Performance Evaluation of Stone Mastic Asphalt and Hot Mix Asphalt Mixtures Containing Recycled Concrete Aggregate

    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.

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

    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. PMID:26687102

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

    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. The ITZ in concrete with natural and recycled aggregates: Study of microstructures based on image and SEM analysis

    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 an important tool to carry out concrete, cement and aggregate microstructure characterization. SEM imaging facilitates identification of elements in concrete. Thanks to the higher spatial resolutio...

  16. INVESTIGATION ON MECHANICAL PROPERTIES OF STRUCTURAL LIGHTWEIGHT CONCRETE MADE WITH PUMICE AGGREGATE

    Selçuk TÜRKEL

    2007-03-01

    Full Text Available In this study, structural lightweight concrete mixtures are produced by using Kayseri pumice aggregate. The other constituent materials used in producing the lightweight concrete mixtures are; CEM I 42.5 cement as binder, silica fume and fly ash as mineral admixtures. The following properties are determined; slump, unit weight and air content of fresh mix, as well as unit weight, compressive strength, splitting tensile strength and flexural strength of hardened concrete. Test results show that the lightweight concrete mixtures prepared from Kayseri pumice have compressive strength far above 17.2 MPa proposed by ACI 213R-87 for structural lightweight concrete. Besides, the lightweight concretes produced in this study meet LC 20/22 and LC 25/28 strength classes given by TS EN 206-1.

  17. Analysis of moisture state of recycled coarse aggregate and its influence on compression strength of the concrete

    Pelufo Carbonell, María José; Domingo Cabo, Alberto; Ulloa Mayorga, Vivián Andrea; VERGARA ACUÑA, NEEDY NAYIV

    2009-01-01

    p. 2932-2940 This article analyzes the impact of the moisture level of recycled coarse aggregate additions to concrete on its compression strength, with the goal of finding a logical development process that can be reproduced at an industrial level and provide acceptable results for concrete production. This study takes into account the reality in the process of the production of concrete; while many authors suggest the use of recycled coarse aggregates in a saturated state to ensure the d...

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

    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. PMID:26168872

  19. Comparision of Strength For Concrete With Rock Dust And Natural Sand Concrete As Fine Aggregate

    V.Ashok Kumar

    2015-11-01

    Full Text Available The Quarry rock dust can be an economic alternative to the river sand. Quarry Rock Dust can be defined as residue, tailing or other non-voluble waste material after the extraction and processing of rocks to form fine particles less than 4.75mm. Usually, Quarry Rock Dust is used in large scale in the highways as a surface finishing material and also used for manufacturing of hollow blocks and lightweight concrete prefabricated Elements. This project presents the feasibility of the usage of Quarry Rock Dust as hundred percent substitutes for Natural Sand in concrete. Design Mix for M30 and M40 has been calculated using IS 10262-2009 for both conventional concrete and quarry dust concrete. Tests were conducted on cubes, cylinders and beams to study the strength of concrete by using Quarry Rock Dust and the results were compared with the Natural Sand Concrete. Cement motor ratios of 1:3 and 1:6 are prepared and observe the percentage of water absorption in both Quarry Rock Dust and Natural sand for plastering.

  20. Environmental Sustainability by Use of Recycled Aggregates - An Overview

    D. K. Gandhi

    2014-05-01

    Full Text Available Optimum utilization of available natural resources is the major component to achieve the environmental sustainability. Development in urban infrastructure demands for large quantity of aggregates for construction. Infrastructural waste in the form of demolished aggregates is one of the major components of solid waste. By efficient use of these demolished aggregates in the form of recycled aggregates along with fresh aggregates can achieve a better solid waste management and also cope up with the rising demands of aggregates leading to economy. Present study is an attempt to increase the awareness about economical viability and technical feasibility for the use of recycled aggregates as a construction material in concrete and to show that the use of recycled aggregates is also an efficient measure to reduce the intensity of environmental impact.

  1. Oil Palm Fiber as Partial Replacement Aggregates for Normal Concrete

    1Wasiu John,; 2 Salami Victor ,; 3Awolusi T.F

    2015-01-01

    This study is focused on assessing the effectiveness of palm kernel shell (PKS) as partial replacement aggregates for normal concrete. The tests carried out on PKS concrete at a constant water cement ratio of 0.5 with mix ratios 1:2:4 and 1:1 : 3 with PKS varied from 0%-30%. The results of the slump and compaction factor test showed that all mixes were workable for all replacement levels considered. The compressive strength values obtained ranges between 32.2N...

  2. Hot sodium-triggered thermo-chemical degradation of concrete aggregates in the sodium resistant sacrificial layers of fast breeder reactors

    Highlights: • Concrete aggregates were exposed to liquid sodium exposure at 550 °C. • Thermal and chemical effects were studied using megascopic and micro-analytical techniques. • Aggregates underwent significant thermo-chemical degradation upon exposure. • Limestone found more suitable for sodium environment than siliceous aggregate. - Abstract: Sodium is used as an efficient coolant in fast breeder reactor (FBR) for extracting nuclear heat from its high power density core to steam generator, to produce electricity. Accidentally spilled Sodium at elevated temperatures of 550 °C or above may interact with concrete leading to its deterioration. A sacrificial concrete layer is provided on the structural concrete to mitigate the harmful impacts of these interactions. Locally available crushed rocks like limestone and granite are employed as aggregates in sacrificial and structural concrete respectively. Rocks are naturally occurring multi-mineral and multiphase inorganic systems of the earth. Aggregates are the main constituents of concrete accounting for 70–80% of its mass. In this paper, an attempt is made to study the physico-chemical modifications that may occur in the aggregates during the interactions between liquid sodium and the aggregates of concrete. The experimental strategy consists of heating of granite, limestone and river sand aggregates at 550 °C for 30 min and further treating them with 1 Normal aqueous solution of NaOH, to differentiate thermal and chemical effects. Furthermore, sodium-aggregate interaction study at 550 °C was conducted to characterize the combined effects of heat and sodium. Siliceous aggregates (granite and river sand) were found to be easily attacked by ferric oxidation during heating in air and also subjected to rapid chemical reactions with liquid NaOH, producing mineral phases of sodium silicate, sodium orthosilicates, calcium orthosilicates and sodium carbonates. Initiation and propagation of cracking in the

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

    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. PMID:22951223

  4. The Method of Evaluation and Implementation of the Non-destructive Test on Aggregate denuded Concrete Structure for Irrigation and Drainage

    Ogata, Hidehiko; Sato, Shushi; Hattori, Kunio

    The surfaces of the servicing concrete structure for irrigation and drainage have the denuding aggregates. Various diagnoses can't be done properly by the test method for ultrasonic pulse velocity, because close adhesion between pulse terminal and aggregate denuded concrete surface is insufficient. In this research, the solution of this problem by coating method that mediated material is applied to the concrete was examined. As a result, the ultrarapid hardening cement and the epoxy clay were suitable as a mediated material, and the method to evaluate ultrasonic pulse velocity of the coated concrete by the mediated material were clarified. Moreover, the method to evaluate rebound number and impact points of the coated concrete by the mediated material was recommended.

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

    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.

  6. The influence of steel fibres content and pre-soaked lightweight aggregate on shrinkage of high strength concrete

    Žnidaršič, Špela

    2012-01-01

    This thesis studies high strength concrete reinforced with steel fibers and pre-soaked lightweight aggregate. Steel fibers added to the steel mixture represented 0.5% of the total volume. 12% of the aggregate was replaced with pre-soaked lightweight aggregate. The focus of the analysis was on the autogenous shrinkage, which is very distinct at high strength concrete. The shrinkage was measured electronically during the first day. Later we measured it with a mobile displacement transducer.Besi...

  7. Experimental Study on Performance of Concrete M30 with Partial Replacement of Coarse Aggregate with Sea Shells and Coconut Shells

    Gurikini Lalitha

    2014-08-01

    Full Text Available In this research work experiments have been conducted with collection of materials required and the data required for mix design are obtained by sieve analysis and specific gravity test. Sieve analysis is carried out from various fine aggregates (FA and coarse aggregates (CA samples and the sample which suits the requirement is selected. Specific gravity tests are carried out for fine and coarse aggregate. The various materials used were tested as per Indian standard specifications. On the basis of the experimental studies carried out on M30 grade concrete as partial replacement of coarse aggregates with sea shells and coconut shells, the following conclusions are drawn from the above experiment we conclude that comparing to traditional concrete, compressive strength of 10% (5% + 5% of coconut shells (5% and sea shells (5% increased. whereas the compressive strength of the concrete cubes has gradually decreased from addition of 10% (5% + 5% of coconut shells and sea shells. Hence for economical view 10% is preferable and in the perspective of compressive strength 10% is suggested. Thus, 10% replacement coconut shells and sea shells are recommended for both heavy weight and light weight concrete production.

  8. Influence of aggregate shapes on drying and carbonation phenomena in 3D concrete numerical samples

    This study aims at generating numerical 3D samples of concrete so as to study the effects of the granular inclusions shape on the macroscopic kinetics of reactive transport phenomena. Two types of meso-structure configurations are considered: the first one is composed of a matrix of mortar in which are randomly distributed inclusions corresponding to the concrete coarse aggregates, and the second one also includes a steel rebar. The choice of a mesoscopic modeling for the mortar matrix is based on the need to obtain numerical structures of reasonable size. In particular, the Interfacial Transition Zones (ITZs) are assumed to be incorporated into the homogenized mortar properties. This study is applied to the case of drying and atmospheric carbonation by using simplified models solved by the finite element code Cast3M. The purpose is to quantify the influence of the aggregate shape on the kinetics of macroscopic transfer and the iso-value lines for some physical variables representative of the reactive transport problems: saturation degree for drying, and porosity, calcite and portlandite concentrations for carbonation. Basic aggregates shapes are studied (spheres, cubes), as well as more complex ones (Voronoi particles) which are supposed to be more representative of real aggregates. The effects of 'non-isotropic' shapes (oblate and prolate ones) are also investigated. It is shown that the influence of the aggregate shapes appears negligibly small on macroscopic indicators, except for oblate shapes with aspect ratios of 3. This latter case also exhibits substantial local delayed effects and a more important variability, which may have some importance for a precise description and estimation of degradation processes related to steel rebar corrosion. (authors)

  9. Mechanical Properties of Concrete with Marine Sand as Partial Replacement of Fine Aggregate

    Dr. V.Ravindra,

    2016-02-01

    Full Text Available The process of depleting sources of natural aggregates challenges the production of technically and environmentally adequate concrete. Alternative material from marine sources is good enough for the replacement of fine aggregate in the concrete. The material was stockpiled in the open air and no washing, drying or decontamination process was carried out. Physical and chemical properties of DMS material were determined. All the materials used in the concrete were selected and tested as per the standard procedures of the Indian standards. A unique design mix will be done based on the entire material test results. Different mixtures were produced using DMS in different proportions from 15% to 100% as per the finalized trial of the design mix. The concrete were submitted to compressive strength testsafter 7, 28 and 90 days of moist curing, as well as flexure and splitting tensile strength tests for M-25 grade.

  10. Use of plastic waste (poly-ethylene terephthalate) in asphalt concrete mixture as aggregate replacement.

    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. PMID:16200982

  11. The Influence of Aggregate Size and Binder Material on the Properties of Pervious Concrete

    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.

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

    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. Evaluating Deterioration of Concrete by Sulfate Attack

    2007-01-01

    Effects of factors such as water to cement ratio, fly ash and silica fume on the resistance of concrete to sulfate attack were investigated by dry-wet cycles and immersion method. The index of the resistance to sulfate attack was used to evaluate the deterioration degree of concrete damaged by sulfate. The relationship between the resistance of concrete to sulfate attack and its permeability/porosity were analyzed as well as its responding mechanism. Results show that the depth of sulfate crystal attack from surface to inner of concrete can be reduced by decreasing w/c and addition of combining fly ash with silica fume. The variation of relative elastic modulus ratio and relative flexural strength ratio of various specimens before and after being subjected to sulfate attack was compared.

  14. The estimation of compressive strength of normal and recycled aggregate concrete

    Janković Ksenija

    2011-01-01

    Full Text Available Estimation of concrete strength is an important issue in ready-mixed concrete industry, especially, in proportioning new mixtures and for the quality assurance of the concrete produced. In this article, on the basis of the existing experimental data of compressive strength of normal and recycled aggregate concrete and equation for compressive strength calculating given in Technical regulation are compared. The accuracies of prediction by experimental data obtained in laboratory as well as by EN 1992-1-1, ACI 209 and SRPS U.M1.048 are compared on the basis of the coefficient of determination. The determination of the compressive strengths by the equation described here relies on determination of type of cement and age of concrete with the constant curing temperature.

  15. Strength and Durability of Concrete: Effects of Cement Paste-Aggregate Interfaces, Part I: Theoretical Study on Influence of Interfacial Transition Zone on Properties of Concrete Materials

    Zhang, Yiguo; Chen, Wai-Fah

    1998-01-01

    This research was based on a two-part basic research investigation studying the effects of cement paste-aggregate interfaces (or interfacial transition zones-HZ) on strength and durability of concrete. Part I dealt with the theoretical study and Part II dealt with the experimental. Part I, the theoretical part, illustrates the effect of ITZ on the concrete properties by assuming its elastic moduli to be varied continuously in the region. A four-phase composite model is employed and three func...

  16. A study on drying shrinkage and creep of recycled concrete aggregate

    CASTAÑO, Jesus O.; LOPEZ-GAYARRE, Fernando; Lázaro Fernández, Carlos Manuel; Domingo Cabo, Alberto

    2009-01-01

    p. 2955-2964 Although it is not a new material, in the last years the recycled aggregates of concrete RCA have had a great progress and are highly valued because of being friendly with the environment, multiple studies find feasible their use in structural concrete but when it is intended to be used in singular structures or prefabricated pieces that require high performance levels an exhaustive evaluation of its properties dealing with deformation and durability are needed. Th...

  17. Use of contaminated recycled aggregates for concrete design: properties and durability

    Courard, Luc; Michel, Frédéric; Debieb, Farid

    2012-01-01

    Construction waste management is a quite important economic and environmental deal for our societies. More than 2 million tons demolition and construction wastes are annually produced only in Wallonia, Southern Region of Belgium; recycling has clearly to be promoted. Roller Compacted Concrete (RCC) is a special dry concrete made of aggregates, water and low quantity of cement, laid down and compacted like a soil, for the construction of massive structures like dams or large horizontal surface...

  18. Optimizing the Mixing Proportion with Neural Networks Based on Genetic Algorithms for Recycled Aggregate Concrete

    Sangyong Kim; Hee-Bok Choi; Yoonseok Shin; Gwang-Hee Kim; Deok-Seok Seo

    2013-01-01

    This research aims to optimize the mixing proportion of recycled aggregate concrete (RAC) using neural networks (NNs) based on genetic algorithms (GAs) for increasing the use of recycled aggregate (RA). NN and GA were used to predict the compressive strength of the concrete at 28 days. And sensitivity analysis of the NN based on GA was used to find the mixing ratio of RAC. The mixing criteria for RAC were determined and the replacement ratio of RAs was identified. This research reveal that th...

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

    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...

  20. Effect of surrogate aggregates on the thermal conductivity of concrete at ambient and elevated temperatures.

    Yun, Tae Sup; Jeong, Yeon Jong; Youm, Kwang-Soo

    2014-01-01

    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. PMID:24696666

  1. Laboratory research on disintegration of concretes exposed to high temperature by water jets

    Sitek, L. (Libor); Bodnárová, L.; J. Klich; Foldyna, J.; Hlaváček, P.; Zeleňák, M.

    2013-01-01

    The paper is dealing with effects of flat high-speed water jet on concretes affected by high temperature. Several concrete mixtures were prepared for tests of interaction of water jet with concrete samples: 1)unaffected by high temperature, 2)exposed to 200°C and 3)exposed to 600°C- Achieved results are analyzed and discussed. Research should help especially after wildfires in tunnels, underground garages, etc., which are exposed to enormous thermal stress.

  2. Influence of ageing on the properties of bitumen from asphalt mixtures with recycled concrete aggregates

    Pasandín, A. R.; Pérez, I.; Oliveira, Joel; Silva, Hugo Manuel Ribeiro Dias da; Pereira, Paulo A. A.

    2015-01-01

    The reuse of recycled concrete aggregates in new hot-mix asphalt can be a more sustainable method of production, but these mixtures may need a heat treatment before compaction to improve their water sensitivity performance. A direct consequence of this treatment is an increase in the hot-mix asphalt resilient modulus. The aim of this paper is to analyse the effect of ageing on the stiffness of asphalt mixtures with different amounts of recycled concrete aggregates, before and after a heat tre...

  3. Influencing Factors on the Interface Microhardness of Lightweight Aggregate Concrete Consisting of Glazed Hollow Bead

    Gang Ma; Yu Zhang; Zhu Li

    2015-01-01

    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 pas...

  4. Effect of sedimentary and metamorphic aggregate on static modulus of elasticity of high-strength concrete

    JUAN LIZARAZO-MARRIAGA; LUCIO GUILLERMO LÓPEZ YÉPEZ

    2012-01-01

    Taking into account the increasing use of high-strength concrete as a structural material in Colombia, this paper shows the results of research carried out to investigate the effect of different types of coarse aggregate on the static elastic modulus, the compressive strength, the concrete density, and the pulse velocity. To do this, concrete mixes were cast using three different water binder ratios (w/c) (0.36, 0.32, and 0.28). Ordinary Portland cement and pulverized silica fume (SF) were us...

  5. Efficiency study of superplasticizers to ensure durability of concrete placed by pump.

    Kodelja, Matej

    2009-01-01

    Production of contemporary, high-performance concrete is almost impossible without chemical admixtures, particularly when plastic concrete is placed by pump or when adequate consistency has to be kept from manufacturing to placing of concrete in most environmental conditions. This was the starting point of my diploma work: to choose a chemical admixture - superplasticizer that will be sufficiently effective, practical to use and compatible with available basic materials. I obtained the basic ...

  6. Plain Concrete linearized Stiffness Diminution Modeling Subjected to Different Stresses-Strain Relationship Models

    Linearized stiffness diminution, which is correlated with material damage characteristic, is the major parameters due to modeling of granular material behavior such as plain concrete subjected to cyclic loading. Many damage equations in tension and compression states are proposed in the literatures, however, they produces different damages considering the concepts of the equation's development without any capability of fitting and calibration of produced damages curves with any arbitrary test records. In the present paper, the new equations of concrete damages in the tension and compression state with calibration capability based on the two separated damage indices are developed based on linear interpolation hypothesis. In the result, it is shown that the present equations can be produced the damage parameters close to experimental data.

  7. Performance Evaluation of Stone Mastic Asphalt and Hot Mix Asphalt Mixtures Containing Recycled Concrete Aggregate

    Mohammad Saeed Pourtahmasb; Mohamed Rehan Karim

    2014-01-01

    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 t...

  8. 再生粗骨料混凝土性能的研究%Researching of using waste concrete as coarse aggregate

    段献智

    2012-01-01

    Use the waste concrete taken from several different locations and different service lives as the coarse aggregate,and make those coarse aggregate into the recycled concrete that have several different water-cement ratio and slump by different match,then test and compare the early properties of the fresh concrete.The results show that under the same conditions,the mobility of the recycled concrete poorer than the ordinary concrete.The setting time of the recycled concrete shorter than the ordinary concrete.And generally,the compressive strength of recycled concrete decreased with the recycled aggregate dosage increased.The higher water absorption of recycled aggregate,the lower compressive strength of recycled concrete.By the use of various complexed methods,we can get more higher compressive strength of the recycled concrete.The recycled coarse aggregate that mixed to the recycled aggregate concrete,in which the strength of the original concrete is low,has different effect to the recycled concrete with lower water-cement ratio and higher water-cement ratio.%将几种取自不同地点的废弃混凝土破碎制成粗骨料,然后通过不同搭配,配制成几种不同水灰比、坍落度的再生混凝土,并对其新拌混凝土早期的性能进行测试比较,研究结果表明,在相同条件下,再生混凝土的流动性比普通混凝土的差;再生混凝土的凝结时间比普通混凝土要短;再生混凝土的抗压强度一般随再生骨料掺量的增加而降低;吸水率高的再生骨料对应的再生混凝土强度低;通过各种方法的复合运用,可配得较高抗压强度的再生混凝土;混合再生骨料配制的再生混凝土,其中原始混凝土强度低的再生骨料,对低水灰比和高水灰比的再生混凝土有不同的影响效果。

  9. Experimental study on microstructure and structural behaviour of recycled aggregate concrete

    Etxeberria Larrañaga, Miren

    2004-01-01

    The use of recycled aggregates in concrete opens a whole new range of possibilities in the reuse of materials in the building industry. This could be an important breakthrough for our society in our endeavours towards sustainable development. The trend of the utilisation of recycled aggregates is the solution to the problem of an excess of waste material, not forgetting the parallel trend of improvement of final product quality. The utilisation of waste construction materials has to be relat...

  10. Shrinkage cracking of lightweight concrete made with cold-bonded fly ash aggregates

    Mehmet Gesoglu; Turan Ozturan; Erhan Guneyisi [Bogazici University, Istanbul (Turkey). Department of Civil Engineering

    2004-07-01

    Shrinkage cracking performance of lightweight concrete (LWC) has been investigated experimentally on ring-type specimens. LWCs with and without silica fume were produced at water-cementitious material ratios (w/cm) of 0.32 to 0.55 with cold-bonded fly ash coarse aggregates and natural sand. Coarse aggregate volume ratios were 30%, 45%, and 60% of the total aggregate volume in the mixtures. A total of 12 lightweight aggregate concrete mixtures was cast and tested for compressive strength, static elastic modulus, split-tensile strength, free shrinkage, weight loss, creep, and restrained shrinkage. It was found that the crack opening on ring specimens was wider than 2 mm for all concretes. Free shrinkage, weight loss, and maximum crack width increased, while compressive and split-tensile strengths, static elastic modulus, and specific creep decreased with increasing coarse aggregate content. The use of silica fume improved the mechanical properties but negatively affected the shrinkage performance of LWCs. Shrinkage cracking performance of LWCs was significantly poorer than normal weight concrete (NWC).

  11. Impact Behavior of Recycled Aggregate Concrete Based on Split Hopkinson Pressure Bar Tests

    Yubin Lu; Xing Chen; Xiao Teng; Shu Zhang

    2013-01-01

    This paper presents the experimental results of recycled aggregate concrete (RAC) specimens prepared with five different amounts of recycled coarse aggregate (RCA) (i.e., 0, 25%, 50%, 75%, and 100%) subjected to impact loading based on split Hopkinson pressure bar tests. Strain-rate effects on dynamic compressive strength and critical strain of RAC were studied. Results show that the impact properties of RAC exhibit strong strain-rate dependency and increase approximately linearly with strain...

  12. High performance of treated and washed MSWI bottom ash granulates as natural aggregate replacement within earth-moist concrete.

    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. PMID:26856445

  13. Influence of Bottom Ash Replacements as Fine Aggregate on the Property of Cellular Concrete with Various Foam Contents

    Patchara Onprom

    2015-01-01

    Full Text Available This research focuses on evaluating the feasibility of utilizing bottom ash from coal burning power plants as a fine aggregate in cellular concrete with various foam contents. Flows of all mixtures were controlled within 45 ± 5% and used foam content at 30%, 40%, 50%, 60%, and 70% by volume of mixture. Bottom ash from Mae Moh power plant in Thailand was used to replace river sand at the rates of 0%, 25%, 50%, 75%, and 100% by volume of sand. Compressive strength, water absorption, and density of cellular concretes were determined at the ages of 7, 14, and 28 days. Nonlinear regression technique was developed to construct the mathematical models for predicting the compressive strength, water absorption, and density of cellular concrete. The results revealed that the density of cellular concrete decreased while the water absorption increased with an increase in replacement level of bottom ash. From the experimental results, it can be concluded that bottom ash can be used as fine aggregate in the cellular concrete. In addition, the nonlinear regression models give very high degree of accuracy (R2>0.99.

  14. Effects of Magnetite Aggregate and Steel Powder on Thermal Conductivity and Porosity in Concrete for Nuclear Power Plant

    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.

  15. Mineralogy, size, morphology and porosity of aggregates and their relationship with soil susceptibility to water erosion

    Soil erosion has been considered as the main process related to losses of soil mass and decrease of productivity in cultivated lands as well as on e of the most important processes in landscape evolution. Attention has been paid to many pedological variables affecting intensity of erosion, but little to the influence of iron compounds on the type, size, shape and porosity of soil aggregates. In the present study, three lithopedodomains which were assumed to be closely related to the dominant lithology of the soil parent material, varying in the degree of water erosion intensity, were selected for further analysis which focused mainly on the influence of iron oxide mineralogy on the soil aggregation. Powder X-ray diffractometry, 80 K Moessbauer data and SEM images are used to correlate all these variables with observed erosion activity in the field. The present data indicate that the more the soil is rich in iron (hematite and/or goethite) or aluminium (gibbsite) (hydr)oxide, the smaller are its aggregates and is porous. Soils derived from metabasic rocks are much more susceptible to collapse under wetting than those from other lithologies. They have the highest iron and clay content. Schist-derived soil is richer in muscovite, has bigger aggregates and porous and are less prone to collapse, while the granite-derived soil presents relatively intermediate resistance, when humid

  16. Caracterização microestrutural da argila expandida para aplicação como agregado em concreto estrutural leve Microstructural evaluation of expanded clay to be used as lightweight aggregate in structural concrete

    W. G. Moravia

    2006-06-01

    Full Text Available A utilização da argila expandida como agregado graúdo é economicamente viável na fabricação de concretos devido à redução da massa especifica que estes agregados proporcionam, minimizando os carregamentos atuantes nas estruturas. O objetivo deste trabalho é caracterizar a microestrutura do agregado leve de argila expandida visando sua utilização na fabricação de concretos. Na caracterização física da argila expandida foram avaliadas a massa unitária, a granulometria e a absorção de água por imersão total do agregado. Na caracterização microestrutural, foram realizadas análise química, microscopia eletrônica de varredura, difração de raios X e porosimetria por intrusão de mercúrio. A argila expandida apresentou granulometria entre as britas com graduação 0 e 1, e apresentou alta absorção de água devido à elevada porosidade deste agregado. Na análise de difração de raios X evidenciou-se a presença de sílica na forma mineral de alfa-quartzo, silicato de magnésio e óxido de alumínio e magnésio.The use of expanded clay as aggregate is economically feasible in the manufacturing of concrete due to the decrease in bulk density, provided by these aggregates, minimizing the total weight of the structures. The objective of this work is to characterize the microstructure of expanded clay aggregates which are used in the manufacturing of lightweight concretes. The expanded clay was evaluated concerning of the density, the granulometry and water absorption after total immersion of the aggregate. The chemical analysis, scanning electron microscopy, X-ray diffraction and mercury intrusion porosimetry were used as well. The expanded clay presented granulometry between the aggregates grades 0 and 1 and high water absorption due to the high porosity of the aggregate. The X-ray diffraction data showed the presence of alpha-quartz, magnesium silicate and magnesium aluminum oxide.

  17. In-plane Shear Joint Capacity of Pracast Lightweight Aggregate Concrete Elements

    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...

  18. Lightweight concrete blocks with EVA recycled aggregate: a contribution to the thermal efficiency of building external walls

    De Melo, A. B.

    2013-12-01

    Full Text Available The regions with lots of shoe production suffer environmental impacts from waste generation during manufacturing of insoles and outsoles. Research conducted in Brazil has demonstrated the technical feasibility to recycle these wastes, especially Ethylene Vinyl Acetate (EVA, as lightweight aggregate, in the production of non-structural cement blocks. This article presents an evaluation of thermal performance with measurements of temperature variation in mini walls (1 m2 built with different materials, including various kinds of EVA block and ceramic bricks. Tests have shown efficient thermal performance for masonry blocks with EVA. These results and supplementary estimates contribute to add value to the EVA block, considering that there are good expectations that the component, with the new geometry proposed, can contribute to the energy efficiency of buildings, highlighting its suitability to most Brazilian bioclimatic regions.Las regiones con una gran producción de calzado sufren impactos ambientales derivados de la generación de residuos durante la producción de plantillas y suelas. Investigaciones realizadas en Brasil han demostrado la viabilidad técnica para el reciclaje de estos residuos, especialmente el Etileno Vinil Acetato (EVA, como agregado ligero en la fabricación de bloques de hormigón no estructurales. Este trabajo presenta una evaluación del rendimiento térmico, con mediciones de la variación de la temperatura en pequeñas paredes (1 m2 construidas con diversos materiales, incluyendo algunos tipos de bloques EVA y ladrillos de cerámica. Las pruebas demostraron actuaciones térmicas eficientes para las muestras con bloques EVA. Estos resultados y cálculos adicionales contribuyen con un aporte de valor añadido al bloque EVA, considerando que existen buenas expectativas del componente, con una nueva propuesta de geometría, pudiendo contribuir a la eficiencia energética de edificios, especialmente por su adecuación a la

  19. Pore Structure and Influence of Recycled Aggregate Concrete on Drying Shrinkage

    Yuanchen Guo

    2013-01-01

    Full Text Available Pore structure plays an important role in the drying shrinkage of recycled aggregate concrete (RAC. High-precision mercury intrusion and water evaporation were utilized to study the pore structure of RAC, which has a different replacement rate of recycled concrete aggregate (RCA, and to analyze its influence on drying shrinkage. Finally, a fractal-dimension calculation model was established based on the principles of mercury intrusion and fractal-geometry theory. Calculations were performed to study the pore-structure fractal dimension of RAC. Results show the following. (1 With the increase in RCA content, the drying shrinkage values increase gradually. (2 Pores with the greatest impact on concrete shrinkage are those whose sizes ranging from 2.5 nm to 50 nm and from 50 nm to 100 nm. In the above two ranges, the proportions of RAC are greater than those of RC0 (natural aggregate concrete, NAC, which is the main reason the shrinkage values of RAC are greater than those of NAC. (3 The pore structure of RAC has good fractal feature, and the addition of RCA increases the complexity of the pore surface of concrete.

  20. Fiber-reinforced polymer concrete: Property improvement by gamma irradiation

    Martinez B, G. [Laboratorio de Investigacion y Desarrollo de Materiales Avanzados, Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Km. 12 Carretera Toluca-Atlacomulco, San Cayetano 50200, Estado de Mexico (Mexico); Brostow, W. [Laboratory of Advanced Polymers and Optimized Materials, Department of Materials Science and Engineering, University of North Texas, Denton TX 76203-5310 (United States)], e-mail: gonzomartinez02@yahoo.com.mx

    2009-07-01

    Polymer concrete (PC) is a particulate composite in which a thermoset resin forms a polymeric matrix and binds inorganic aggregates (dispersed particles of strengthening phases). This in contrast to Portland cement concrete (PCC) in which the binding is a result of interaction of cement with water. Adding polymeric materials to the concrete one can obtain high compressive and flexural strength, high impact and abrasion resistance, lower weight and lower costs. Moreover, PC is a very good repair material for structure elements damaged by trapping water inside the structure and by acid attacks which take place in the PCC. In the present chapter we discuss uses of polymer concrete and the importance of using gamma radiation as a novel technology for manufacturing fiber-reinforced polymer concrete. Our technology is different from the costly and time consuming current procedures such as chemical attack or thermal treatment. (Author)

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

    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.

  2. THE EFFECT OF AGGREGATE MAXIMUM SIZE ON IMPACT RESISTANCE OF FIBER REINFORCED CONCRETE

    Şemsi YAZICI

    2008-03-01

    Full Text Available In this study, the effect of maximum size of aggregate on impact resistance of fiber reinforced concrete were investigated. Using crushed limestone aggregate with 10, 15, 20 and 25 mm of maximum size, 8 different normal-steel fiber reinforced concretes were produced. Water/cement ratio and cement dosage of concrete mixtures are 0.5 and 400 kg/m3, respectively. Hooked-end bundled steel fibers with l/d ratio of 65 and 1.0% fiber volume were used in fiber concretes. After 28 days standard curing, compressive strength, split tensile strength and ultrasonic pulse velocity tests were performed on 150/150/150 mm cube specimens. Additionally, impact resistances of concrete specimens were determined using impact test apparatus described in ACI 544.3R-93. 150x300 mm cylinders were prepared for impact resistance tests. After 28 days curing, these specimens were cut and 150x64 mm special discs were prepared. Impact resistance test were performed on these special discs. Experimental results were evaluated corresponding to presence of steel fiber and aggregate maximum size.

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

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

    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 resu...

  4. Application of micro X-ray diffraction to investigate the reaction products formed by the alkali silica reaction in concrete structures

    Dähn, R.; Arakcheeva, A.; Schaub, Ph.; Pattison, P.; Chapuis, G.; Grolimund, D.; Wieland, E.; Leemann, A. (Ecole); (PSI); (Phase Solutions); (ESRF)

    2015-12-21

    Alkali–silica reaction (ASR) is one of the most important deterioration mechanisms in concrete leading to substantial damages of structures worldwide. Synchrotron-based micro-X-ray diffraction (micro-XRD) was employed to characterize the mineral phases formed in micro-cracks of concrete aggregates as a consequence of ASR. This particular high spatial resolution technique enables to directly gain structural information on ASR products formed in a 40-year old motorway bridge damaged due to ASR. Micro-X-ray-fluorescence was applied on thin sections to locate the reaction products formed in veins within concrete aggregates. Micro-XRD pattern were collected at selected points of interest along a vein by rotating the sample. Rietveld refinement determined the structure of the ASR product consisting of a new layered framework similar to mountainite and rhodesite. Furthermore, it is conceivable that understanding the structure of the ASR product may help developing new technical treatments inhibiting ASR.

  5. Durability and acoustics of concrete with slag of cupola furnace as fine aggregate replacement

    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.

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

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

    2015-08-01

    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.

  7. The valorization of local aggregates in the manufacturing of high-performance concrete (case study of Southwest of Algeria)

    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)

  8. Experimental study on C20 no-fines pervious concrete made by recycled aggregate%再生骨料制备C20无砂混凝土的试验研究

    左文銮; 魏勇; 范建峰; 陈雷

    2014-01-01

    主要以废弃混凝土制得再生骨料,通过试验研究不同水胶比,不同颗粒级配的再生骨料制备的无砂混凝土的力学性能,透水性能,抗冻性能。试验结果表明由再生骨料制备的C20无砂混凝土的性能和水胶比及再生骨料的级配相关,其强度满足一般道路基层的需求,透水性能和抗冻性能良好。%The concrete mainly made of recycled aggregate through the experiments to research the mechanics performance,the water-proof performance and the antifreeze performance of the recycled concrete under the different water/cement ratio and the different particle size distribution of the recycled aggregate.The result showed that the performance of the recycled concrete was about to the water/cement ratio and the different particle size distribution of the recycled aggregate,and it met the needs of the general road base on its strength,it also has good waterproof performance and antifreeze performance.

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

    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.

  10. MECHANICAL BEHAVIOR OF HIGH PERFORMANCE CONCRETE WITH RECYCLED AGGREGATES = ESTUDO MECÂNICO DO CONCRETO DE ALTO DESEMPENHO COM AGREGADO RECICLADO

    Maria da Consolação Fonseca de Albuquerque; Aparecido Carlos Gonçalves

    2010-01-01

    The utilization of recycled aggregates can minimize environmental impact, and decreases the consumption of natural resources used for concrete applications. However, recycled aggregates are not suitable for use in the production of High Performance Concrete (HPC) due to their relatively high absorption capacity, instable properties and weaker strength. Such difficulties can be overcome through selection and partial substitution of aggregates. In this paper, recycled aggregates generated from ...

  11. Data relationship degree-based clustering data aggregation for VANET

    Kumar, Rakesh; Dave, Mayank

    2016-03-01

    Data aggregation is one of the major needs of vehicular ad hoc networks (VANETs) due to the constraints of resources. Data aggregation in VANET can reduce the data redundancy in the process of data gathering and thus conserving the bandwidth. In realistic applications, it is always important to construct an effective route strategy that optimises not only communication cost but also the aggregation cost. Data aggregation at the cluster head by individual vehicle causes flooding of the data, which results in maximum latency and bandwidth consumption. Another approach of data aggregation in VANET is sending local representative data based on spatial correlation of sampled data. In this article, we emphasise on the problem that recent spatial correlation data models of vehicles in VANET are not appropriate for measuring the correlation in a complex and composite environment. Moreover, the data represented by these models is generally inaccurate when compared to the real data. To minimise this problem, we propose a group-based data aggregation method that uses data relationship degree (DRD). In the proposed approach, DRD is a spatial relationship measurement parameter that measures the correlation between a vehicle's data and its neighbouring vehicles' data. The DRD clustering method where grouping of vehicle's data is done based on the available data and its correlation is presented in detail. Results prove that the representative data using proposed approach have a low distortion and provides an improvement in packet delivery ratio and throughput (up to of 10.84% and 24.82% respectively) as compared to the other state-of-the-art solutions like Cluster-Based Accurate Syntactic Compression of Aggregated Data in VANETs.

  12. The Accelerated Test of Chloride Permeability of Concrete

    TAN Ke-feng; ODD E Gjφrv

    2003-01-01

    The availability of accelerated chloride permeability test and the effect of w/c ratio, incorporation of silica fume, maximum aggregate size and aggregate type on the chloride permeability were studied. The mathematic analysis certifies that there is a linear relationship between accelerated test and natural diffusion. Test results show that the chloride permeability of concrete increases as w/c ratio increases whilst a limited amount of replacement of cement with silica fume, the chloride permeability decreases dramatically. The maximum aggregate size in the range of 8 to 25 mm seems also affect chloride permeability but with a much less significant level. The chloride permeability of silica fume lightweight aggregate concrete is very low, especially the concrete made with dry lightweight concrete. The chloride permeability can be evaluated by this accelerated test method.

  13. Evaluation of recycled concrete by means of non destructive tests

    Di Maio, E. A.; Traversa, L. P.

    2003-01-01

    The use of recycled concrete as aggregate for the production of new concretes is a consequence of the shortage of natural resources and the environmental problems due to the storage of residual building materials. In this paper the following results are given: compressive strength, rebound numbers, ultrasonic pulse velocity Break-off pressure and torsional moment, all of them determined on concretes of different strength level elaborated with recycled coarse aggregate in 25% and 75% in respec...

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

    Both hexagonal and cubic calcium aluminate cement (CAC) hydrates react with atmospheric CO2, 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

  15. Experimental measurement of double-K fracture parameters of concrete with small-size aggregates

    ZHANG Xiufang; XU Shilang; ZHENG Shuang

    2007-01-01

    The double-K fracture model can well describe the development of cracks undergoing during the entire fracture process in concrete.Therefore,it has been selected as the theoretical basis of the"Norm for fracture test of hydraulic concrete" (China) and the double-K fracture parameters proposed in this model are regarded as the essential fracture parameters needed to be measured.Therefore,the primary objection of this paper is to present an overall report on the determination of the double-K fracture parameters of concrete involving the fundamental theory,calculation formulas,experimental arrangement and identification of initial cracking load in order to provide a reference for the specification committee.The fracture tests are carried out on the total of 43 concrete specimens where the small-size aggregates with the maximum size of 10 mm are chosen.Two typical widelyused geometries,I.e.three-points bending beam and wedge splitting specimen are adopted.The initial cracking load is determined by means of graph method or electrical resistance strain gauge method.Then,the initial fracture toughness and unstable fracture toughness are measured.It is found that the ratio of initial cracking load to maximum load is 0.67-0.71 and the ratio of initial fracture toughness to unstable fracture toughness is 0.45-0.50.It is also found that,for the initial fracture toughness and unstable fracture toughness,the values are approximately close to the constants when the depth of specimens is larger than 200 and 400 mm for three-points bending beams and wedge splitting specimens respectively.Besides,the critical crack tip opening displacement of each specimen is calculated,too.The big difference between two geometries is noticed.

  16. A Comparative Analysis of Modulus of Rupture and Splitting Tensile Strength of Recycled Aggregate Concrete

    Akinkurolere Olufunke Olanike

    2016-07-01

    Full Text Available - In this experimental investigation, an attempt is made to report the comparative analysis of the modulus of rupture and the splitting tensile strength of recycled aggregate concrete. The two properties are usually used to estimate the tensile strength of concrete; however, they don’t usually yield the same results hence need to investigate each of the properties. Taguchi optimization technique was employed to reduce the number of trials needed to get the results. The results showed that the splitting tensile strength ranges between 60-80% of the modulus of rupture which is also known as the flexural strength.

  17. Effect of Glass Powder on Chloride Ion Transport and Alkali-aggregate Reaction Expansion of Lightweight Aggregate Concrete

    WANG Zhi; SHI Caijun; SONG Jianming

    2009-01-01

    The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated.Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re-placement of cement with 25% glass powder slightly decreases the strengthes at 7 and 28 d, but shows no effect on 90 d's. Silica fume is very effective in improving both the strength and chloride penetra-tion resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete.

  18. Physical Model of Drying Shrinkage of Recycled Aggregate Concrete

    GUO Yuanchen; WANG Xue; QIAN Jueshi

    2015-01-01

    We prepared concretes (RC0, RC30, and RC100) with three different mixes. The pore-size distribution parameters of RAC were examined by high-precision mercury intrusion method (MIM) and nuclear magnetic resonance (NMR) imaging. A capillary-bundle physical model with random-distribution pores (improved model, IM) was established according to the parameters, and dry-shrinkage strain values were calculated and verified. Results show that in all pore types, capillary pores, and gel pores have the greatest impacts on concrete shrinkage, especially for pores 2.5-50 and 50-100 nm in size. The median radii are 34.2, 31, and 34 nm for RC0, RC30, and RC100, respectively. Moreover, the internal micropore size distribution of RC0 differs from that of RC30 and RC100, and the pore descriptions of MIM and NMR are consistent both in theory and in practice. Compared with the traditional capillary-bundle model, the calculated results of IM have higher accuracy as demonstrated by experimental veriifcation.

  19. Structural Lightweight Concrete Production by Using Oil Palm Shell

    Habibur Rahman Sobuz

    2014-01-01

    Full Text Available Conventional building materials are widely used in a developing country like Malaysia. This type of material is costly. Oil palm shell (OPS is a type of farming solid waste in the tropical region. This paper aims to investigate strength characteristics and cost analysis of concrete produced using the gradation of OPS 0–50% on conventional coarse aggregate with the mix proportions 1 : 1.65 : 2.45, 1 : 2.5 : 3.3, and 1 : 3.3 : 4.2 by the weight of ordinary Portland cement, river sand, crushed stone, and OPS as a substitution for coarse aggregate. The corresponding w/c ratios were used: 0.45, 0.6, and 0.75, respectively, for the defined mix proportions. Test results indicate that compressive strength of concrete decreased as the percentage of the OPS increased in each mix ratio. Other properties of OPS concrete, namely, modulus of rupture, modulus of elasticity, splitting tensile strength, and density, were also determined and compared to the corresponding properties of conventional concrete. Economic analysis also indicates possible cost reduction of up to 15% due to the use of OPS as coarse aggregate. Finally, it is concluded that the use of OPS has great potential in the production of structural lightweight concrete.

  20. Seismic Performance of Composite Shear Walls Constructed Using Recycled Aggregate Concrete and Different Expandable Polystyrene Configurations

    Wenchao Liu; Wanlin Cao; Jianwei Zhang; Qiyun Qiao; Heng Ma

    2016-01-01

    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 ra...

  1. 循环再生高性能混凝土细骨料性能研究%Research on properties of fine recycled aggregate for structural concrete from repeatedly recycling concrete waste

    牟晓芳; 郑俊健; 李浩然; 朱平华

    2014-01-01

    系统研究了由废弃混凝土二次再生制备的结构混凝土细骨料性能,分析了矿物与化学成分,依据日本JISA、美国ASTM和中国GB/T 25176-2010等相关再生细骨料标准对试验结果进行了等级评定,并建立了表观密度、胶砂强度与吸附砂浆含量之间的关系。结果表明:随着循环次数的增加,再生细骨料表观密度、吸水率、需水量比降低,胶砂强度比与细度模数增大,吸附的砂浆含量上升;与天然细骨料相比,首次与第二次再生细骨料中CaO的质量分数平均增长了5、10倍;再生细骨料胶砂强度与吸附砂浆含量呈二次曲线关系。不论采用什么标准,二次循环再生细骨料均满足结构混凝土用细骨料的性能要求。%In order to explore the possibility of repeatedly recycling the waste concrete from different sources for structural concrete ag-gregate,the experiment researched the performance of recycled fine aggregate from both secondary renewable single sources and mixed sources,analysing the mineral and chemical component,grading the test results according to Japanese technical standards for recycled ag-gregate,ASTM and China GB/T 25177-2010 and other relevant recycled aggregate standards,establishing a relationship between aggre-gate indicators through the data fitting.The experimental results show that:with the increase of the cycle,the apparent density of recycled fine aggregate,the water absorption and water demand ratio decreases while the intensity ratio increases;the surface absorption mortar con-tent of circulation recycled aggregate increases;compared with natural fine aggregate,the mass fraction of CaO from first recycled fine ag-gregate increased by an average of 5 times,which from the second recycled fine aggregate increased by an average of 10 times;the com-pressive strength radio of recycled mortar and the absorption mortar content shows a quadratic relationship ,the curve down first then

  2. Repair and protection of concrete structures damaged by reinforcement corrosion

    Likar, Andrej

    2006-01-01

    The present work is focused on repair of concrete structures damaged by reinforcement corrosion. First part describes properties of primary components in concrete (cement, water, aggregate). Further are described mechanical properties of concrete and reinforcement and their compatibility. Second part introduces kinds of processes which causes corrosion of reinforcement in concrete. There are two emphasized chemical processes which cause corrosion of reinforcement, carbonation and chloride dif...

  3. The Compression-deformation Behaviour of Concrete with Various Modified Recycled Aggregates

    DU Ting; LI Huiqiang; WU Xianguo; QIN Yawei

    2005-01-01

    Modified recycled aggregates were prepared with three different cement-admixture grouts. The physical properties, such as water absorption, apparent density, crushing index, slump and compressive strength of the recycled aggregate and the recycled concretes were tested, and the tests for the compression-deformation behavior of the concretes were also performed. The experimental results show that the cement-Kim powder grout is satisfied for enhancing the recycled concrete, and the modification of the recycled aggregate with the grouts can improve the toughness and the deformation ability of the concretes.

  4. Influencing Factors on the Interface Microhardness of Lightweight Aggregate Concrete Consisting of Glazed Hollow Bead

    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.

  5. The Simple Lamb Wave Analysis to Characterize Concrete Wide Beams by the Practical MASW Test

    Young Hak Lee; Taekeun Oh

    2016-01-01

    In recent years, the Lamb wave analysis by the multi-channel analysis of surface waves (MASW) for concrete structures has been an effective nondestructive evaluation, such as the condition assessment and dimension identification by the elastic wave velocities and their reflections from boundaries. This study proposes an effective Lamb wave analysis by the practical application of MASW to concrete wide beams in an easy and simple manner in order to identify the dimension and elastic wave veloc...

  6. Studies on Pumice Lightweight Aggregate Concrete with Quarry Dust Using Mathematical Modeling Aid of ACO Techniques

    J. Rex

    2016-01-01

    Full Text Available The lightweight aggregate is an aggregate that weighs less than the usual rock aggregate and the quarry dust is a rock particle used in the concrete for the experimentation. The significant intention of the proposed technique is to frame a mathematical modeling with the aid of the optimization techniques. The mathematical modeling is done by minimizing the cost and time consumed in the case of extension of the real time experiment. The proposed mathematical modeling is utilized to predict four output parameters such as compressive strength (Mpa, split tensile strength (Mpa, flexural strength (Mpa, and deflection (in mm. Here, the modeling is carried out with three different optimization techniques like genetic algorithm (GA, particle swarm optimization (PSO, and ant colony optimization (ACO with 80% of data from experiment utilized for the training and the remaining 20% for the validation. Finally, while testing, the error value is minimized and the performance obtained in the ACO for the parameters such as compressive strength, split tensile strength, flexural strength, and deflection is 91%, 98%, 87%, and 94% of predicted values, respectively, in the mathematical modeling.

  7. Discussion on “Malešev, M.; Radonjanin, V.; Marinković, S. Recycled Concrete as Aggregate for Structural Concrete Production. Sustainability, 2010, 2, 1204-1225”

    Gholamreza Fathifazl

    2011-02-01

    Full Text Available The authors are to be congratulated for their comprehensive research work on the use of RCA as aggregate in structural grade concrete [1], but some of their conclusions with regard to the effect of aggregate type and RCA content on the fresh and hardened properties of concrete made with coarse RCA, termed RAC for brevity, need discussion.

  8. Discussion on “MaleÅ¡ev, M.; Radonjanin, V.; Marinković, S. Recycled Concrete as Aggregate for Structural Concrete Production. Sustainability , 2010, 2 , 1204-1225â€

    Gholamreza Fathifazl; A. Ghani Razaqpur

    2011-01-01

    The authors are to be congratulated for their comprehensive research work on the use of RCA as aggregate in structural grade concrete [1], but some of their conclusions with regard to the effect of aggregate type and RCA content on the fresh and hardened properties of concrete made with coarse RCA, termed RAC for brevity, need discussion.

  9. Discussion on “Malešev, M.; Radonjanin, V.; Marinković, S. Recycled Concrete as Aggregate for Structural Concrete Production. Sustainability, 2010, 2, 1204-1225”

    Gholamreza Fathifazl; A. Ghani Razaqpur

    2011-01-01

    The authors are to be congratulated for their comprehensive research work on the use of RCA as aggregate in structural grade concrete [1], but some of their conclusions with regard to the effect of aggregate type and RCA content on the fresh and hardened properties of concrete made with coarse RCA, termed RAC for brevity, need discussion.

  10. Effect of Aggregate Gradation with Fuller Distribution on Properties of Sulfoaluminate Cement Concrete

    Gong, Chenchen; Jie ZHANG; Wang, Shoude; Zong, Wen; Lu, Lingchao

    2014-01-01

    Aggregate, the main ingredient of concrete, has a great effect on mechanical property and durability of concrete. Sulfoaluminate cement has lots of special properties such as high early-age compressive strength, fast hydration and setting rate, and hydration with slight swelling. But effect of aggregate gradation with Fuller distribution on properties of sulfoaluminate cement concrete was seldom studied. Hence, in this paper, experimental investigations on mechanical property and durability o...

  11. Mechanical Properties of Concrete with Marine Sand as Partial Replacement of Fine Aggregate

    Dr. V.Ravindra,; Anil Kumar Buraka

    2016-01-01

    The process of depleting sources of natural aggregates challenges the production of technically and environmentally adequate concrete. Alternative material from marine sources is good enough for the replacement of fine aggregate in the concrete. The material was stockpiled in the open air and no washing, drying or decontamination process was carried out. Physical and chemical properties of DMS material were determined. All the materials used in the concrete were selected and teste...

  12. The influence of coarse aggregate size and volume on the fracture behavior and brittleness of self-compacting concrete

    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 (GF) and the value measured through SEM (Gf) (GF = 3.11Gf)

  13. NONLINEAR ANALYSIS OF CFRP- PRESTRESSED CONCRETE BEAMS SUBJECTED TO INCREMENTAL STATIC LOADING BY FINITE ELEMENTS

    Husain M. Husain; Nazar K. Oukaili

    2013-01-01

    In this work a program is developed to carry out the nonlinear analysis (material nonlinearity) of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP) instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. a...

  14. Experimental Study on Forecasting Mathematical Model of Drying Shrinkage of Recycled Aggregate Concrete

    Guo, Yuanchen; Wang, Xue

    2012-01-01

    On the basis of basic law in AASHTO2007 model, the forecasting mathematical model of drying shrinkage of recycled aggregate concrete (RAC) is established by regression analysis and experimental study. The research results show that (1) with the replacement rate of RCA increases, the drying shrinkage value of RAC increases; this trend is even more obvious in the early drying time. (2) The addition of fly ash can inhibit the drying shrinkage of RAC, but the effect is not very obvious. Specifica...

  15. Influence of mixed recycled aggregate on the physical e mechanical properties of recycled concrete

    Medina Martínez, César; Zhu, Wenzhong; Howind, Torsten; Sánchez de Rojas, María Isabel; Frías Rojas, Moisés

    2014-01-01

    This article discusses the findings of a feasibility study on the partial replacement of natural coarse aggregate with a poor quality recycled aggregate from construction and demolition waste in the manufacture of concrete of 30 MPa strength grade. The mixed recycled aggregate used had a high asphalt and floating material content. Workability, density, compressive and tensile strength, water absorption and sorptivity were studied in a series of concretes containing 25 or 50% of th...

  16. Investigation of Self Consolidating Concrete Containing High Volume of Supplementary Cementitious Materials and Recycled Asphalt Pavement Aggregates

    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

  17. Humidity and aggregate content correction factors for air-coupled ultrasonic evaluation of concrete.

    Berriman, J; Purnell, P; Hutchins, D A; Neild, A

    2005-02-01

    This paper describes the use of non-contact ultrasound for the evaluation of concrete. Micromachined capacitance transducers are used to transmit ultrasonic longitudinal chirp signals through concrete samples using air as the coupling medium, and a pulse compression technique is then employed for measurement of time of flight through the sample. The effect on the ultrasonic wave speed of storing concrete samples, made with the same water/cement ratio, at different humidity levels is investigated. It is shown that there is a correlation between humidity and speed of sound, allowing a correction factor for humidity to be derived. A strong positive linear correlation between aggregate content and speed of sound was then observed; there was no obvious correlation between compressive strength and speed of sound. The results from the non-contact system are compared with that from a contact system, and conclusions drawn concerning coupling of energy into the samples. PMID:15567195

  18. Monte Carlo simulations of mesoscale fracture modelling of concrete with random aggregates and pores

    Wang XF, Yang ZJ, Yates JR, Jivkov AP, Zhang Ch

    2015-01-01

    A procedure for generating two-dimensional heterogeneous meso-scale concrete samples is developed, in which the multi-phasic features including the shape, size, volume fraction and spatial distribution of aggregates and pores are randomised. Zero-thickness cohesive interface elements with softening traction–separation relations are pre-inserted within solid element meshes to simulate complex crack initiation and propagation. Extensive Monte Carlo simulations (MCS) of uniaxial tension tests ...

  19. Durability and acoustics of concrete with slag of cupola furnace as fine aggregate replacement

    Ricardo Alfredo Cruz Hernández; Carlos Mauricio Pico Cortés; Ludwing Pérez Bustos

    2015-01-01

    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 % conc...

  20. Linear relationship statistics in diffusion limited aggregation

    Saberi, Abbas Ali, E-mail: a_saberi@ipm.i [School of Physics, Institute for Research in Fundamental Sciences (IPM), PO Box 19395-5531, Tehran (Iran, Islamic Republic of)

    2009-11-18

    We show that various surface parameters in two-dimensional diffusion limited aggregation (DLA) grow linearly with the number of particles. We find the ratio of the average length of the perimeter and the accessible perimeter of a DLA cluster together with its external perimeters to the cluster size, and define a microscopic schematic procedure for attachment of an incident new particle to the cluster. We measure the fractal dimension of the red sites (i.e., the sites such that cutting each of them splits the cluster) as equal to that of the DLA cluster. It is also shown that the average number of dead sites and the average number of red sites have linear relationships with the cluster size.

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

    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.

  2. Exploratory Study of Rubber Seed Shell as Partial Coarse Aggregate Replacement in Concrete

    K. Muthusamy

    2014-02-01

    Full Text Available Malaysia being a major rubber trees growing country has been generating a large amount of rubber seed shell which regarded as waste. At the same time, the growing construction industry which boosts the concrete production trade has results in higher consumption of natural coarse aggregate which open the door for depletion of this material in future. This study focuses on investigating the possibility of integrating crushed rubber seed shell as partial coarse aggregate replacement material in concrete making. Total of five mixes consisting various content of crushed rubber seed shell as partial coarse aggregate replacement ranging from 0, 5, 10, 15 and 20%, respectively were prepared in form of cubes. All the specimens were water cured before tested at 7 and 28 days. The workability test, compressive strength test and flexural strength test of the mixes was conducted in accordance to MS26 Part 1: Section 2, BSEN 12390 and ASTM 293-79 respectively. Generally, workability, compressive strength and flexural strength decrease with the increase in the crushed rubber seed shell replacement level. However, mix consisting around 10% of crushed rubber seed shell is suitable for the application in concrete work.

  3. Compressive strength evaluation of structural lightweight concrete by non-destructive ultrasonic pulse velocity method.

    Bogas, J Alexandre; Gomes, M Glória; Gomes, Augusto

    2013-07-01

    In this paper the compressive strength of a wide range of structural lightweight aggregate concrete mixes is evaluated by the non-destructive ultrasonic pulse velocity method. This study involves about 84 different compositions tested between 3 and 180 days for compressive strengths ranging from about 30 to 80 MPa. The influence of several factors on the relation between the ultrasonic pulse velocity and compressive strength is examined. These factors include the cement type and content, amount of water, type of admixture, initial wetting conditions, type and volume of aggregate and the partial replacement of normal weight coarse and fine aggregates by lightweight aggregates. It is found that lightweight and normal weight concretes are affected differently by mix design parameters. In addition, the prediction of the concrete's compressive strength by means of the non-destructive ultrasonic pulse velocity test is studied. Based on the dependence of the ultrasonic pulse velocity on the density and elasticity of concrete, a simplified expression is proposed to estimate the compressive strength, regardless the type of concrete and its composition. More than 200 results for different types of aggregates and concrete compositions were analyzed and high correlation coefficients were obtained. PMID:23351273

  4. THE EFFECT OF AGGREGATE MAXIMUM SIZE ON IMPACT RESISTANCE OF FIBER REINFORCED CONCRETE

    YAZICI, Şemsi; Gözde İNAN SEZER

    2008-01-01

    In this study, the effect of maximum size of aggregate on impact resistance of fiber reinforced concrete were investigated. Using crushed limestone aggregate with 10, 15, 20 and 25 mm of maximum size, 8 different normal-steel fiber reinforced concretes were produced. Water/cement ratio and cement dosage of concrete mixtures are 0.5 and 400 kg/m3, respectively. Hooked-end bundled steel fibers with l/d ratio of 65 and 1.0% fiber volume were used in fiber concretes. After 28 days standard curing...

  5. A study on the mix design and fundamental properties of pre-cast concrete artifacts prepared with coarse and fine recycled aggregates

    Garcia Navarro, Justo; Guzmán Báez, Ana de; Cervantes Villamuelas, Miguel

    2010-01-01

    This paper analyzes the use of Construction and Demolition Waste as aggregate in precast concrete artifacts production incorporating coarse and fine fractions. The recycled aggregates used were sourced from a Spanish sorting facility and were mainly composed of concrete rubbles and ceramic materials. A complete study of the properties of the aggregates was carried out and laboratory trials were conducted to investigate the possibility of the use of 10%, 20%, 30% and 50% contents of coa...

  6. Flexural strengthening of reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted GFRP bars

    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)

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

    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.

  8. A comparative study of recycled aggregates from concrete and mixed debris as material for unbound road sub-base; Estudio comparativo de los aridos reciclados de hormigon y mixtos como material para sub-bases de carreteras

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

    2011-07-01

    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.

  9. The Importance of Superplastizer Dosage in the Mix Design of Lightweight Aggregate Concrete Reinforced With Plypropylene Fiber

    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.

  10. Relation of expansion due to alkali silica reaction to the degree of reaction measured by SEM image analysis

    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

  11. Analytical studies on local damage to reinforced concrete structures under impact loading by discrete element method

    This paper proposes a new analytical approach for assessing local damage to reinforced concrete structures subjected to impact load, by applying the discrete element method (DEM). It first outlines the basis concept and analytical formulation of the DEM. Next, it discusses the results of simulation analyses of concrete material tests, uni-axial compression tests and tensile splitting tests conducted to determine appropriate analytical parameters such as material constants, failure criteria and strength increase factors depending on strain rate. Finally, the adaptability of the DEM to local damage to reinforced concrete structures impacted by rigid and deformable missiles is verified through simulation analyses of various types of impact tests. Furthermore, the various impact response characteristics and failure mechanisms, such as impact forces, penetration behavior, reduction in missile velocity and energy transfer process, which are difficult to obtain experimentally, are analytically evaluated by the DEM. (orig.)

  12. Fire Resistance of Concrete Constructions with Expanded Clay Aggregate

    Hertz, Kristian Dahl

    The paper describes briefly a series of full-scale tests made as documentation for extending the field of application of the reduced cross section method from the structural codes to constructions based on expanded clay aggregate. As a special result the tests verify that slabs with a short...

  13. HIGH PERFORMANCE CONCRETE WITH GGBS AND ROBO SAND

    VENU MALAGAVELLI; Rao, P N

    2010-01-01

    Concrete is a mixture of cement, fine aggregate, coarse aggregate and water. Concrete plays a vital role in the development of infrastructure Viz., buildings, industrial structures, bridges and highways etc. leading to utilization of large quantity of concrete. High Performance Concrete (HPC) is a concrete meeting special combinations of performance and uniformity requirements that cannot be always achieved routinely by using conventional constituents and normal mixing. This leads to examine ...

  14. 高强再生骨料混凝土的配制及性能研究%Research on high-strength recycled aggregate concrete preparation and performance

    杨海涛; 田石柱

    2013-01-01

    Using recycled coarse aggregate strength in 50MPa or greater strength of recycled aggregate concrete, mensurate the deformation capacity and durability to provide theoretical and experimental basis for application of the high strength recycled aggregate concrete in engineering.Determine the ultimate strength of recycled coarse aggregate through a series of compression test.By adj usting the water cement ratio,make the high-strength recycled aggregate concrete on strength to reach the design strength and have experiment on high-strength recycled aggregate concrete with recycled coarse aggregate replacement rate 0,30%,50%,80% and 100%.When the replacement ratio of recycled coarse aggregate was 30%,it has little effect on the strength of recycled concrete.Then the strength of concrete was reducing as the recycled aggregate was increasing.High-strength recycled aggregate concrete and natural concrete have similar performance in durability.Therefore high-strength recycled aggregate concrete can be applied to engineering.%采用再生粗骨料配制强度在50MPa或更大的高强再生骨料混凝土,并对其变形能力和耐久性进行测定,为高强再生骨料混凝土在工程上的应用提供理论和实验基础。通过一系列的抗压实验确定再生粗骨料的强度极限,并通过对水灰比的调整,使配制的高强再生骨料混凝土在强度上达到设计值,并以再生粗骨料取代率为0、30%、50%、80%和100%的高强再生骨料混凝土为研究对象进行实验。当再生粗骨料取代率为30%时,对再生混凝土的强度影响不大;之后混凝土强度随再生骨料的增加而降低。高强再生骨料混凝土与天然混凝土在耐久性上具有相似的性能,可以将高强再生混凝土应用于工程中。

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

    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.

  16. Quality evaluation of aged concrete by ultrasound

    Tavossi, H. M.; Tittmann, Bernhard R.; Cohen-Tenoudji, Frederic

    1999-02-01

    The velocity, attenuation and scattering of ultrasonic waves measured in concrete, mortar and cement structures can be used to evaluate their quality with weathering and aging. In this investigation the hardening of concrete mixture with time is monitored by ultrasonic waves under different conditions of temperature and water to cement ratio. The measured ultrasonic parameters can then be utilized to determine the final quality of the completely cured concrete structure from initial measurement. The quality of a concrete structure is determined by its resistance to compression and its rigidity, which should be within the acceptable values required by the design specifications. The internal and external flaws that could lower its strength can also be detected by ultrasonic technique. Aging process of concrete by weathering can be simulated in the laboratory by subjecting the concrete to extremes of cold and hot cycles in the range of temperatures normally encountered in summer and winter. In this research ultrasonic sensors in low frequency range of 40 to 100 kHz are used to monitor the quality of concrete. Ultrasonic pulses transmitted through the concrete sample are recorded for analysis in time and frequency domains. ULtrasonic waves penetration in concrete of the order of few feet has been achieved in laboratory. Data analyses on ultrasonic signal velocity, spectral content, phase and attenuation, can be utilized to evaluate, in situ, the quality and mechanical strength of concrete.

  17. Application of Desalination with CFRP Composite Electrode to Concrete Deteriorated by Chloride Attack

    Yamaguchi, Keisuke; Ueda, Takao; Nanasawa, Akira

    As a new rehabilitation technique for recovery both of loading ability and durability of concrete structures deteriorated by chloride attack, desalination (electrochemical chloride removal technique from concrete) using CFRP composite electrode bonding to concrete has been developed. In this study, basic application was tried using small RC specimens, and also application to the large-scale RC beams deteriorated by the chloride attack through the long-term exposure in the outdoors was investigated. As the result of bending test of treated specimens, the decrease of strengthening effect with the electrochemical treatment was observed in the case of small specimens using low absorption rate resin for bonding, on the other hand, in the case of large-scale RC beam using 20% absorption rate resin for bonding CFRP composite electrode, enough strengthening effect was obtained by the bending failure of RC beam with the fracture of CFRP board.

  18. Steel slag aggregate in concrete: the effect of ageing on potentially expansive compounds

    Frías, M.

    2010-02-01

    Full Text Available Growing numbers of plants have sprung up in recent years to treat the electric arc furnace slag generated in scrap metal melting. When this by-product is separated, crushed and screened, it yields a granular material known as steel slag aggregate, which may be profitably used in the manufacture of commercial concrete. The feasibility of this application depends essentially on the volume stability of the resulting aggregate. The present paper discusses the potentially expansive compounds (Cl-, SO3, free CaO and free MgO present in aggregate derived from different types of black slag during aggregate ageing. The aim is to establish optimal ageing conditions to ensure volume stability in steel slag aggregate. The findings showed that the slag analyzed had low concentrations of the expansive compounds studied and that possible swelling can be reduced by 45day ageing.

    En los últimos años están surgiendo diferentes plantas de tratamiento de las escorias generadas en el proceso de fusión de la chatarra en los hornos de arco eléctrico. Mediante procesos de separación, machaqueo y cribado se obtiene un material granular denominado árido siderúrgico, que puede ser atractivo para su utilización en la fabricación de hormigones comerciales. En este sentido, la viabilidad de dicha aplicación dependerá, fundamentalmente, de asegurar su estabilidad en volumen. Este trabajo presenta un estudio de los compuestos potencialmente expansivos (Cl-, SO3, CaO libre y MgO libre de los áridos siderúrgicos procedentes de diferentes tipos de escorias negras, así como su evolución después de un proceso de envejecimiento. El objetivo es establecer las condiciones óptimas de un proceso de envejecimiento a partir del cual se pueda asegurar la estabilidad, en volumen, del árido siderúrgico. Los resultados evidencian que las escorias analizadas tienen bajas concentraciones de los compuestos expansivos

  19. Acoustic properties of porous concrete made from arlite and vermiculite lightweight aggregates

    Carbajo, J; Esquerdo-Lloret, T. V.; Ramis, J.; Nadal-Gisbert, A. V.; Denia, F. D.

    2015-01-01

    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....

  20. Recycling power plant slag for use as aggregate in precast concrete components

    Orna Carmona, M.

    2010-12-01

    Full Text Available The need to eliminate waste generates costs. When considering the preservation of the environment, the minimization of the consumption of natural resources and energy savings criteria, the need and advisability of studying the feasibility of waste re-use seems clear. However, waste re-use depends on whether they are economically competitive. Therefore, the aim of this study is to evaluate the possible use of slag from a steam power station as aggregate in the manufacture of concrete. This study included the determination of the physical, chemical and thermal properties of the material, comparing the results to those required by the Spanish structural concrete code (EHE in determining their acceptance or rejection as a concrete component. The ultimate aim of the research was to determine the highest slag content that could be added to concrete without modifying its strength or durability, with a view to obtaining savings in the manufacture of precast structures.

    La necesidad de eliminar residuos genera gastos. Considerando criterios de conservación ambiental, minimización del consumo de recursos naturales y ahorro de energía parece claro la necesidad y conveniencia de estudiar la viabilidad del uso de residuos. Sin embargo la utilización de residuos depende de que sean competitivos económicamente. Por tanto el propósito de esta investigación es evaluar el posible uso de las escorias de fondo de una central térmica como áridos para la fabricación de hormigón. En este estudio se incluye la determinación de características físicas, químicas y térmicas y se han comparado los resultados a los requeridos por la EHE para determinar su aceptación o rechazo como componente de un hormigón. El objetivo final de la investigación responde a la utilización de hormigón con el máximo contenido en escorias sin modificar las condiciones de resistencia y durabilidad, consiguiendo un ahorro económico en la fabricación de estructuras

  1. Concreting method that produce high modulus of elasticity

    Abdelgader H.S.; Elbaden A.S.

    2014-01-01

    During the last decades, the concrete industry has been widely developing in many ways such as the methods of pouring concrete in order to achieve high quality concrete and low cost. Two-stage concrete is characterised by a higher proportion of coarse aggregate therefore the variation in aggregate content influences significantly its mechanical properties. The mechanical characteristics of the two-stage concrete (TSC) in failure conditions are dissimilar from the ordinary ones. Behaviour of T...

  2. Up-cycling waste glass to minimal water adsorption/absorption lightweight aggregate by rapid low temperature sintering: optimization by dual process-mixture response surface methodology.

    Velis, Costas A; Franco-Salinas, Claudia; O'Sullivan, Catherine; Najorka, Jens; Boccaccini, Aldo R; Cheeseman, Christopher R

    2014-07-01

    Mixed color waste glass extracted from municipal solid waste is either not recycled, in which case it is an environmental and financial liability, or it is used in relatively low value applications such as normal weight aggregate. Here, we report on converting it into a novel glass-ceramic lightweight aggregate (LWA), potentially suitable for high added value applications in structural concrete (upcycling). The artificial LWA particles were formed by rapidly sintering (shrinkage during sintering, density and water adsorption/absorption. The diametrical expansion could be effectively modeled via the RSM and controlled to meet a wide range of specifications; here we optimized for LWA structural concrete. The optimally designed LWA is sintered in comparatively low temperatures (825-835 °C), thus potentially saving costs and lowering emissions; it had exceptionally low water adsorption/absorption (6.1-7.2% w/wd; optimization target: 1.5-7.5% w/wd); while remaining substantially lightweight (density: 1.24-1.28 g.cm(-3); target: 0.9-1.3 g.cm(-3)). This is a considerable advancement for designing effective environmentally friendly lightweight concrete constructions, and boosting resource efficiency of waste glass flows. PMID:24871934

  3. Improvement of Bearing Capacity in Recycled Aggregates Suitable for Use as Unbound Road Sub-Base

    Laura Garach

    2015-12-01

    Full Text Available Recycled concrete aggregates and mixed recycled aggregates are specified as types of aggregates with lower densities, higher water absorption capacities, and lower mechanical strength than natural aggregates. In this paper, the mechanical behaviour and microstructural properties of natural aggregates, recycled concrete aggregates and mixed recycled aggregates were compared. Different specimens of unbound recycled mixtures demonstrated increased resistance properties. The formation of new cement hydrated particles was observed, and pozzolanic reactions were discovered by electronon microscopy in these novel materials. The properties of recycled concrete aggregates and mixed recycled aggregates suggest that these recycled materials can be used in unbound road layers to improve their mechanical behaviour in the long term.

  4. Effect of the type of mineral aggregate on the high-temperature creep of HTR-concrete

    Within the scope of the research and development work for the prestressed concrete vessel of the HTR 500 High-Temperature Reactor mix design, manufacture as well as mechanical and thermal behavior of the concrete have been comprehensively studied. Of the concrete types analyzed, a basalt concrete showed extremely favorable high-temperature characteristics while a concrete with Rhine gravel was characterized by a good workability. These two types of concrete were subjected to numerous tests, whereby the testing procedures were strongly related to the anticipated combined stress, temperature and moisture conditions in the real structure

  5. Observations on dedolomitization of carbonate concrete aggregates, implications for ACR and expansion

    Prinčič, Tina, E-mail: Tina.Princic@uni-lj.si [University of Ljubljana, Faculty of Chemistry and Chemical Technology, Aškerčeva 5, 1000 Ljubljana (Slovenia); Štukovnik, Petra [University of Ljubljana, Faculty of Civil and Geodetic Engineering, Jamova 2, 1000 Ljubljana (Slovenia); Pejovnik, Stane [University of Ljubljana, Faculty of Chemistry and Chemical Technology, Aškerčeva 5, 1000 Ljubljana (Slovenia); De Schutter, Geert [Magnel Laboratory for Concrete Research, Department of Structural Engineering, Ghent University, B9052 Ghent (Belgium); Bokan Bosiljkov, Violeta [University of Ljubljana, Faculty of Civil and Geodetic Engineering, Jamova 2, 1000 Ljubljana (Slovenia)

    2013-12-15

    Some carbonate aggregates used in concrete are unstable in a high alkaline solution, which is present also in pore solution of cement binder. This paper investigates the process of dedolomitization of carbonate aggregate rocks and mortar bars. Selected aggregates, limestone and dolostone are of high purity without reactive silica involvement confirmed by the XRD and the XRF. For the process of dedolomitization the effect of various temperatures, solutions and time was examined. In this investigation, measurements of expansion, optical and scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction were used. Te results indicate that the process of dedolomitization occurred not only in the NaOH solution but also in the water on the mortar bar with virgin dolostone aggregate. Elevated temperature, 60 °C, increased the rate of reaction. Furthermore, the rate of reaction significantly correlates with time, which has also been confirmed through the Rietveld analysis. -- Highlights: •The dedolomitization caused no expansion. •It occurs in the dolostone aggregate without reactive silica involvement. •It has taken place already with the presence of the cement binder. •A significant alteration occurred: formation of rims, new pores and phases.

  6. Field site leaching from recycled concrete aggregates applied as sub-base material in road construction.

    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. PMID:22554532

  7. The relationship among money supply, banking lending and aggregate demand in China: 1994-2006

    Li, Qiong; Wang, Zhiwei

    2008-01-01

    Based on the framework of Bernanke & Blinader (1988) and Walsh (2003), this paper provides a concise analysis for relationship among money supply, banking lending and aggregate demand; and makes an empirical test on relationship among China¡¯s money supply, banking lending and aggregate demand from 1994 to 2006 by adopting the single-equation regressive model and vector autoregressive model in terms of Keynesian structural model and monetarism simplified model. The result shows that money sup...

  8. Production and characteristics for concrete waste forms to stabilize concrete waste produced during decommissioning procedure

    Since the decommissioning of nuclear plants and facilities, large quantities of slightly contaminated concrete waste have been generated. In Korea, the decontamination and decommissioning of the KRR-1, 2 at the KAERI have been under way. Concrete waste was generated 83 drums of 200L and 41 containers of 4 M3. These concrete wastes consist of rubble, coarse, and fine aggregates. And also, 24 drums of concrete sludge were generated from the saw cutting of radioactive concrete. The conditioning of concrete waste is needed for final disposal. The concrete waste is conditioned as follows: mortar using coarse and fine aggregates is filled void space after concrete rubble pre-placement into 200 L drum. The mortar needs to be solidified using cement or other materials to protect from sufficient strength and harmful opening. Especially, cement was frequently used solidification/stabilization above all the other ones because of competitive prices, convenient method and excellent quality. Thus, this paper has developed an optimizing mixing ratio of concrete waste, water, and cement and has evaluated characteristics of a cement waste form containing radioactive concrete to meet the requirements specified in disposal site specific waste acceptance criteria

  9. Historic Concrete: From Concrete Repair to Concrete Conservation

    Heinemann, H.A.

    2013-01-01

    Concrete like materials were already applied during the Roman Empire. After the decline of the Roman Empire, a wide scale application of concrete only reappeared in the 19th century. Here lies also the origin of modern (reinforced) concrete. Since then, both concrete application and composition have

  10. Experimental Study on Thermal Conductivity of Self-Compacting Concrete with Recycled Aggregate

    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.

  11. Platelet-collagen adhesion enhances platelet aggregation induced by binding of VWF to platelets

    Ristocetin-induced platelet aggregation (RIPA) was evaluated in the presence of platelet-collagen adhesion. RIPA of normal donor platelet-rich plasma (PRP) demonstrated a primary wave of aggregation mediated by the binding of von Willebrand factor (VWF) to platelets and a secondary aggregation wave, due to a platelet-release reaction, initiated by VWF-platelet binding and inhibitable by acetylsalicylic acid (ASA). An enhanced RIPA was observed in PRP samples to which collagen had been previously added. These subthreshold concentrations of collagen, which by themselves were insufficient to induce aggregation, caused measurable platelet-collagen adhesion. Subthreshold collagen did not cause microplatelet aggregation, platelet release of [3H]serotonin, or alter the dose-responsive binding of 125I-labeled VWF to platelets, which occurred with increasing ristocetin concentrations. However, ASA inhibition of the platelet release reaction prevented collagen-enhanced RIPA. These results demonstrate that platelet-collagen adhesion altered the platelet-release reaction induced by the binding of VWF to platelets causing a platelet-release reaction at a level of VWF-platelet binding not normally initiating a secondary aggregation. These findings suggest that platelet-collagen adhesion enhances platelet function mediated by VWF

  12. The Application of F ine-aggregate Concrete in the Cast-in-place Prestressed Concrete Hollow Slab%细石混凝土在现浇预应力空心楼板结构中的应用

    刘维忠

    2015-01-01

    本文主要介绍了 C40细石混凝土在现浇预应力空心楼板工程实例中的应用,有效解决了预应力空心楼板结构浇筑时泵送难度大、钢筋间距小、填充困难等施工难点,并且通过原材料控制、混凝土生产过程控制、施工现场控制等措施保证 C40细石混凝土的顺利浇筑。经后期检测,满足预应力张拉要求,应用效果理想。%This paper mainly introduced the application of C40 fine-aggregate concrete in the Cast-in-place prestressed concrete hollow slab, the application effectively solved a series of construction difficulties such as small bar spacing, difficult pumping and filling. By taking measures of controlling the quality of materials, concrete production process and the construction site to realize the smooth casting of C40 fine-aggregate concrete. After the later detection, this concrete met the requirements of prestressed tensioning and the application effect proved to be ideal.

  13. RecyMblock - application of recycled mixed aggregates in the manufacture of concrete construction blocks

    Boehme, Luc

    2011-01-01

    With an annual production of 10 million tonnes, construction and demolition waste is one of the most important waste streams in Flanders, Belgium. 95% of this construction and demolition waste (CD&W) is processed into recycled aggregates. The amount of recycled concrete aggregates and the amount of mixed aggregates are about the same. In Flanders, Belgium there is a well developed recycling industry for CD&W, with more than 165 recycling companies on fixed locations and 44 certifi...

  14. The ITZ in concrete with natural and recycled aggregates: Study of microstructures based on image and SEM analysis

    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

  15. Assessment of the Characteristic Aggregates during a Decontamination of Contaminated Concrete Waste

    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. Comparision of Strength For Concrete With Rock Dust And Natural Sand Concrete As Fine Aggregate

    V Ashok Kumar; GVD Kiran

    2015-01-01

    The Quarry rock dust can be an economic alternative to the river sand. Quarry Rock Dust can be defined as residue, tailing or other non-voluble waste material after the extraction and processing of rocks to form fine particles less than 4.75mm. Usually, Quarry Rock Dust is used in large scale in the highways as a surface finishing material and also used for manufacturing of hollow blocks and lightweight concrete prefabricated Elements. This project presents the feasibility of the ...

  17. 轻骨料混凝土的发展与研究展望%The development of lightweight aggregate concrete and Research Prospects

    牛建刚; 林红

    2012-01-01

      本文论述了轻骨料混凝土的发展历程,指出了轻骨料混凝土用于承重结构时的弊病。使用纤维增强轻骨料混凝土,能有效提高轻骨料混凝土的力学性能,使混凝土的抗折、抗裂、抗渗及韧性等性能得到不同程度的改善。在保持轻骨料混凝土质轻特征的前提下,将聚丙烯纤维掺入轻骨料混凝土并用于承重结构将是今后的发展方向。%  This paper discusses the course of development of lightweight aggregate concrete, and points out that the short-comings of lightweight aggregate concrete for load-bearing structure.Fiber reinforced lightweight aggregate concrete, can ef ectively improve the mechanical properties of lightweight aggre-gate concrete, and improve the performance of bending, cracking, impermeability and toughness of concrete to varying degrees.Under the premise of maintaining the lightweight chara- cteristics of lightweight aggregate concrete, the incorporation of polypropylene fiber in lightweight aggregate concrete for the load-bearing structure wil be the future direction of development.

  18. Use of Recycled Concrete Aggregate in Controlled Low-Strength Material (CLSM

    Mustapha K.N.

    2012-01-01

    Full Text Available Use of recycled concrete aggregate (RCA is getting importance as it minimizes the use of fresh materials and eliminates waste disposal. One of the uses of RCA is as aggregate in Controlled Low Strength Material (CLSM. This paper reports the results of the investigation done on the use of RCA in CLSM. Various mixtures of CLSM were made using RCA, fly ash, and cement. Tests for workability, bleeding, density, strength, water absorption, sorption, and ultrasonic pulse velocity (UPV were conducted. Results show that the compressive strength ranged from 1.71 MPa to 4.92 MPa, fresh density from 1879 kg/m3 to 1998 kg/m3. The strength of CLSM increases with the increase in fly ash; water absorption and bleeding decrease with increase in fly ash. It is concluded that the RCA has potential to be used in CLSM and the addition of fly ash enhances the performance.

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

    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...

  20. 再生砖骨料混凝土梁斜截面抗剪承载力分析%Analysis of anti-shear capacity of slope section for recycled brick aggregate concrete beam

    王纯合; 翟爱良; 陈树建; 季昌良; 赵爱华

    2013-01-01

    实验研究了再生砖骨料混凝土梁斜截面的抗剪极限承载力、破坏形态和裂缝开展等情况,并与普通混凝土梁进行对比.分析再生砖骨料混凝土梁的抗剪机理,提出了适用于再生砖骨料混凝上梁的抗剪承载力公式.实验与分析结果表明:再生砖骨料混凝土梁和普通混凝土梁的破坏形态和裂缝开展情况相似,但再生砖骨料混凝土梁的抗剪极限承载力低于普通混凝土梁.采用提出的抗剪承载力公式计算再生砖骨料混凝土梁的抗剪极限承载力是可行的,有一定的安全储备.%The paper studied the ultimate bearing capacity, the fracture morphology and the crack development situation of diagonal section of the recycled brick aggregate concrete beam, and contrasted the beam with common concrete one. By analyzing the shear mechanism of the recycled brick coarse aggregate concrete beams, this paper provided a formula related to the shear capacity of recycled brick aggregate concrete beams. The results show that the fracture morphology and crack development of the recycled brick coarse aggregate concrete beam is similar to common concrete beam, but the ultimate bearing capacity is less then that of the common concrete beam. The formula can be used to calculate the bearing capacity of the recycled brick coarse aggregate concrete beam and contains a certain security reserve.

  1. Constitutive relationships of prestressed steel fiber concrete membrane elements

    Hoffman, Norman S.

    Steel Fiber Concrete (SFC) displays certain tensile and shear characteristics which are beneficial for concrete that is loaded in a state of shear stress. For example, prestressed bridge beams carry shear load in their web by utilizing shear stirrups. If the properties of SFC can be better understood, then it may be possible to replace the shear stirrups with SFC. The first step in understanding this behavior is to develop a constitutive model for prestressed SFC. Two groups of full-scale prestressed steel fiber concrete (SFC) panels, with a nominal strength of 6 ksi, were tested in the Universal Element Testing machine at Thomas TC Hsu Structural Testing Laboratory to establish the effect of fiber and the level of prestress on the constitutive laws of fiber concrete and prestressing tendon. The specimens contained from 5 to 20 fully tensioned, low-relaxation grade 270 tendons. Fiber content ranged from 0.5% to 1.5% using high performance hooked end fibers. The first group of five panels, designated Group TEF, was used to determine the basic constitutive properties of prestressed SEC for use in the Softened Membrane Model (SMM). The constitutive model consists of smeared tensile and compressive stress strain relationships. An equation for softening with respect of both fiber content and tensile strain is presented. Also presented is a new equation for prestressed SFC in tension. It is notable that the behavior of prestressed SFC in tension displayed significant post-cracking tensile strength for fiber contents ranging from 0.5% to 1.5% by volume. Prior research on SFC using unreinforced dog-bone specimens, or prismatic specimens reinforced with only a single isolated tendon, are not capable of capturing SFC behavior afforded by the stress state, multiple load paths, and confinement situation available in full-scale panel assemblies. The second set of 5 test panels, designated Group TAF, was used to examine the properties of prestressed SFC under the conditions of

  2. Erratum to: Study on Chloride Ion Penetration Resistance of Rubberized Concrete Under Steady State Condition

    Md Noor Nurazuwa

    2016-01-01

    In this paper, the effect of crumb rubber, CR as fine aggregate in the concrete to enhance concrete durability against chloride ion diffusion was studied. Chloride ion diffusion in rubberized concrete was tested by migration test under steady state condition. Concrete specimen with water-to-cement ratio of 0.50 was prepared to study the CR effectiveness in comparison with lower water-to-cement ratio. In addition, 10% silica fume, SF was added to provide denser concrete and to understand its effectiveness against chloride ion diffusion. Results showed that chloride transport characteristics were improved by the increasing amount of CR in all mixed due to the fact that CR has the ability to repel water. Meanwhile, rubberized concrete with w/c = 0.35 gave better resistance against chloride ion penetration compared to w/c = 0.50. This was much improved with combination of CR and SF.

  3. 再生骨料替代率对混凝土性能影响的实验分析%Experimental Analysis of the Impact of Recycled Aggregates Replacement Rate on Concrete Properties

    方瑾

    2011-01-01

    Recycled concrete is made from different recycled aggregates replacement rate.Comparing recycled concrete with ordinary concrete from workability,elastic modulus and compressive strength,the article analyzes the impact on the concrete properties from the changes of recycled aggregates substitution rate.The experiment proved that the recycled concrete is equal to ordinary concrete,which is compounded by appropriate recycled aggregates replacement rate.With the emphasis on environmental protection,the development of recycled concrete will be more valuable in application.%用不同的再生骨料替代率,制成再生混凝土。从再生混凝土的和易性、弹性模量和抗压强度等三个方面与普通混凝土进行比较,分析再生骨料替代率的变化对混凝土性能的影响。试验证明,采用适当的再生骨料替代率配制的再生混凝土与普通混凝土基本相当。随着人类对环保的日益重视,再生混凝土产业的发展空间很大,对混凝土的工程应用具有一定的价值意义。

  4. Relationship of Social and Lifestyle Factors with Central Fat Distribution Expressed by the Aggregate Fat Distribution Index

    Suder Agnieszka

    2014-07-01

    Full Text Available Abdominal obesity is caused by several factors and the explanation of the level of its variability also depends on anthropometric indexes applied for its assessment. The aim was to determine the degree of explanation of the abdominal adiposity variation, presented by the aggregate fat distribution index (AFDI, through the socio-economic status and lifestyle. Subjects and methods: A cross-sectional population-based study was conducted on a sample of 259 healthy working males aged 20-30 from the city of Cracow, Poland. A full model was created using a stepwise backward regression with the social and lifestyle data as independent variables and the AFDI as a dependent variable. The AFDI was created by unitarization applied to selected characteristics of fat distribution which were transformed into [0,1] interval (without measurement unit and then added and averaged to form a composite index. The highest autonomous influence on AFDI is ascribed to age (b = 0.2456 p = 0.000, level of motor fitness b=−0.2392 p=0.000, leisure time physical activity (b=−0.1353 p=0.000 and being born in a rural area (b=0.1300 p=0.000. The variables explain 17% (R2=0.1667 of the variation of the central fat distribution. Variation of the abdominal adiposity was explained with the use of AFDI at the level close to the commonly applied indexes.

  5. Donors conference: promises to support Lithuania confirmed by concrete decisions

    Decision to decommission unit 1 of Ignalina NPP was related with possible financial assistance from foreign countries, first of from EU. Government of Lithuania jointly with European Commission on 20 - 21 June 2000 is organising Donors conference in order to collect necessary funds for the decommissioning of unit 1. Preparation to the donors conference is described. Information on the preparation to the decommissioning of unit 1 of Ignalina NPP and the Donors Conference is available on the Internet, web-site address www.ekm.lt/decom

  6. Aggregation of macrophages and fibroblasts is inhibited by a monoclonal antibody to the hyaluronate receptor

    Green, S.J.; Underhill, C.B. (Georgetown Univ. Medical Center, Washington, DC (USA)); Tarone, G. (Univ. of Turin (Italy))

    1988-10-01

    To examine the role of the hyaluronate receptor in cell to cell adhesion, the authors have employed the K-3 monoclonal antibody (MAb) which specifically binds to the hyaluronate receptor and blocks its ability to interact with hyaluronate. In the first set of experiments, they investigated the spontaneous aggregation of SV-3T3 cells, which involves two distinct mechanisms, one of which is dependent upon the presence of divalent cation and the other is independent. The divalent cation-independent aggregation was found to be completely inhibited by both intact and Fab fragments of the K-3 MAb. In contrast, the K-3 MAb had no effect on the divalent cation-dependent aggregation of cells. In a second set of experiments, we examined alveolar macrophages. The presence of hyaluronate receptors on alveolar macrophages was demonstrated by the fact that detergent extracts of these cells could bind ({sup 3})hyaluronate, and this binding was blocked by the K-3 MAb. Immunoblot analysis of alveolar macrophages showed that the hyaluronate receptor had a M{sub r} of 99,500, which is considerably larger than the 85,000 M{sub r} for that on BHK cells. When hyaluronate was added to suspensions of alveolar macrophages, the cells were induced to aggregate. This effect was inhibited by the K-3 MAb, suggesting that the hyaluronate-induced aggregation was mediated by the receptor.

  7. The inlfuence of recycled aggregate on the properties of recycled concrete%再生骨料对再生混凝土性能的影响

    曹玉书; 鲁永明; 龚子亮

    2014-01-01

    Treatment of construction waste in the brick and concrete,recycled aggregate formation.The recycled brick aggregate and recycled concrete aggregate basic properties test,then according to the two components of different proportion of replacement of natural aggregate of recycled concrete was prepared,and the basic properties of recycled concrete.This article concludes:The proportion of broken bricks and waste concrete in recycled aggregate has a significant affect on the performance of recycled concrete.The more content of reclaimed broken bricks, the worse of concrete workability and mechanical properties.While the content of aggregate in recycled concrete aggregate increases, the workability of concrete and mechanical property improved.%对建筑垃圾中的碎砖和废弃混凝土进行处理,生成再生骨料。分别对再生碎砖骨料和再生废混凝土骨料基本性质进行试验,然后根据两种骨料的不同掺配比例替代天然粗骨料进行再生混凝土的配制,并检验再生混凝土的基本性能。结果表明:再生粗骨料中碎砖和废混凝土所占的比例对再生混凝土的性能影响很大。再生碎砖骨料的含量越大,混凝土的工作性越差,力学强度越低。而随着再生废弃混凝土骨料含量的增加,混凝土的工作性良好,力学指标提高。

  8. 配置HRB400钢筋陶粒混凝土梁的试验%An experiment on lightweight aggregate concrete beams reinforced with HRB400

    杜闯; 戎贤; 李艳艳; 刘平

    2012-01-01

    In order to study the mechanical behaviour of lightweight aggregate concrete beams reinforced with HRB400, six specimens were tested. The results demonstrate that the cracking load of lightweight aggregate concrete beam is larger than that of normal concrete beam, but the ultimate loads of both beams are almost the same; that the failure of lightweight aggregate concrete beams is brittle. Under the same loads, the deflection of lightweight aggregate concrete beams is much larger than that gf normal concrete beams, which indicates a smaller stiffness of lightweight aggregate concrete beam. The crack width of lightweight aggregate concrete beam is smaller. The mixing of fibers in lightweight aggregate concrete can significantly enhance the cracking load and reduce the crack width of the beam.%为了研究配置HRB400钢筋陶粒混凝土梁的力学性能,采用试验方法,完成了6根受弯梁的试验研究.结果表明:陶粒混凝土梁的开裂荷载大于普通混凝土梁的,极限承载荷载则和普通混凝土梁的相差不大,破坏时具有显著的脆性特征;在相同荷载作用下,陶粒混凝土梁的挠度比普通混凝土梁的大,刚度则小于普通混凝土梁的;裂缝宽度比普通混凝土梁的小.纤维的加入明显提高了陶粒混凝土梁的开裂荷载,减小了陶粒混凝土梁的裂缝宽度.

  9. Influence of Polyethylene Glycol on Asphaltic Concrete for Cubical and Rod shaped Aggregates

    U. Arun Kumar

    2014-02-01

    Full Text Available Aggregates are the principle material in pavement construction. Conventional road aggregates in India are natural aggregates obtained by crushing rocks. Aggregate characteristics such as particle size, shape, and texture etc.., influence the performance and serviceability of pavement. Pavements laid with polymer modified asphalt exhibits greater resistance to rutting, thermal cracking and fatigue damages and hence these were used at locations of higher stress. The present work concentrates on aggregate characteristics which include the shape indices. The particle shapes namely Cubical and Rod are being used in the study. The study shows the behavior of the two shapes of aggregate in terms of Penetration, Ductility, Softening Point and Marshall Stability tests with varying percentages of asphalt and also with varying the percentages of PEG. The results of unmodified asphalt mix are compared with the modified asphalt mix against some critical Marshall Mix parameters.

  10. 粗集料对粉煤灰混凝土性能影响%Influence of coarse aggregate on properties of fly ash concrete

    汪振双; 王立久

    2011-01-01

    混凝土的架构理论认为混凝土是由砂浆、粗集料和二者之间的界面构成的.试验研究了石灰石、玄武岩、花岗岩和辉绿岩4种不同类型的粗集料对不同粉煤灰掺量混凝土的坍落度、抗压强度、抗折强度和弹性模量的影响,分析了石灰石粗集料对不同粉煤灰掺量混凝土抗冻性的影响.结果表明,粗集料对混凝土的坍落度、抗压强度、抗折强度和弹性模量影响十分显著.粗集料的掺入降低了砂浆基体的扩展度和抗折强度,提高了砂浆基体的抗压强度和弹性模量,此外,粗集料改善了混凝土的抗冻性.随着粉煤灰掺量的增加,混凝土的坍落度提高,但混凝土的力学性能和抗冻性减弱.不同类型的粗集料对混凝土性能的影响相差不大,随着粉煤灰掺量的提高,不同类型粗集料混凝土性能相差也不大.%Concrete is composed of mortar matrix, coarse aggregate and their interface zone according to concrete framework theory. Four different types of coarse aggregate (lime stone, basalt, granite, and diabase) with different volume fraction of fly ash are used to check slump, compressive strength flexural strength and modulus of elasticity, and analyze the influence on frost resistance property o f different fly ash volume fraction for lime stone coarse aggregate. The analytical results show that, slump, compressive strength, flexural strength and modulus of elasticity of concrete are affected by coarse aggregate significantly. Flow ability and flexural strength of concrete are decreased, but compressive strength and modulus of elasticity of concrete are increased due to coarse aggregate mixed, furthermore, coarse aggregate improves frost resistance of concrete. Slump is increased, and mechanical properties and frost resistance property of concrete are decreased with fly ash volume fraction increasing. There is little difference for concrete properties using

  11. Aggregate Relationships between Telecommunications and Travel: Structural Equation Modeling of Time Series Data

    Choo, Sangho

    2003-01-01

    The purpose of this study is to explore the aggregate relationships (substitution, complementarity, or neutrality) between telecommunications and travel and to compare such relationships across transportation modes. This study first presents a conceptual model, considering causal relationships among travel, telecommunications, land use, economic activity, and socio-demographics. Then, based on the conceptual model, the aggregate relationships between telecommunications (local telephone calls,...

  12. Reaction-time relationship and structural design of reinforced concrete slabs and shells for aircraft impact

    This paper outlines a rational procedure by which reinforced concrete structures such as slabs and shells may be designed to retain the required structural integrity after an aircraft impact. The paper presents a new estimate of the reaction-time relationship for impacting aircraft. A new estimate of the punching shear capacity is proposed. In addition, a simple, rotational design procedure is presented. (Auth.)

  13. NONLINEAR ANALYSIS OF CFRP- PRESTRESSED CONCRETE BEAMS SUBJECTED TO INCREMENTAL STATIC LOADING BY FINITE ELEMENTS

    Husain M. Husain

    2013-05-01

    Full Text Available In this work a program is developed to carry out the nonlinear analysis (material nonlinearity of prestressed concrete beams using tendons of carbon fiber reinforced polymer (CFRP instead of steel. The properties of this material include high strength, light weight, and insusceptibility to corrosion and magnetism. This material is still under investigation, therefore it needs continuous work to make it beneficial in concrete design. Four beams which are tested experimentally by Yan et al. are examined by the developed computer program to reach a certain analytical approach of the design and analysis of such beams because there is no available restrictions or recommendations covering this material in the codes. The program uses the finite element analysis by dividing the beams into isoparametric 20-noded brick elements. The results obtained are good in comparison with experimental results.

  14. Activation of pozzolanic and latent-hydraulic reactions by Alkalis in order to repair concrete cracks

    Gruyaert, Elke; Van Tittelboom, Kim; Rahier, Hubert; De Belie, Nele

    2015-01-01

    The low degree of hydration of fly ash (FA) and slag (BFS) particles in high-volume FA and BFS concrete offers the possibility to activate the unreacted particles upon crack formation to close the crack. In this paper, a preliminary study is performed to evaluate the use of alkaline activators to stimulate the formation of reaction products in the crack. First, the reaction rates of crushed pastes mixed with alkaline solutions or water were monitored by calorimetry. These tests showed that al...

  15. Evaluation of the particle size of aggregates used in high density micro-concretes on the gamma-ray linear attenuation coefficient

    Full text: When a component for protecting against ionizing radiation is designed, the main aim to be accomplished is to attenuate radiations to acceptable values, within tolerable limits. Several materials and arrangements can be utilized as protection, among which we can name concrete, steel, lead plates and mortars. Where low-energy radiations (some dozens of keVs) are involved, the main interaction between radiation and the material is the photoelectric effect, whose radiation absorption depends on the photon and specific atomic number of the absorbent. High-density concretes are made by mixing several materials, and the granulometric mixture and proportion of these will determine the physical and chemical features of the product. When the aim is to develop a concrete trace to be utilized as a protection against gamma and X-ray ionizing radiations in low energies, not only aspects of the structural behavior of the component or material must be evaluated, but also the behavior of the composing materials in face of radiation flow must be studied and known in order to develop a concrete with proper performance and that can meet application requirements; among such requirements we can mention the homogeneity of the applied concrete, which directly affects the effective linear attenuation rate of the component and can assure a good performance in face of demands. In this work, our aim was to evaluate what influence the particle size of the aggregates used for producing of assayed concretes has on the variation of the linear attenuation coefficient at different points of the same sample, results which can be used to obtain the inhomogeneity rate of each case of the analyzed concretes. The concrete samples were prepared with small thicknesses, ten millimeters (10 mm) and to perform the assays, a source of Americium-241 was used to transmit gamma-rays in order to determine the variation that existed in the linear attenuation coefficient of each sample. The following

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

    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.

  17. Influence of Electric Arc Furnace (EAF) Slag Aggregate Sizes on the Workability and Durability of Concrete

    P. O. Awoyera; A. W. Adekeye; O E Babalola

    2015-01-01

    The construction industry has been identified as one of the largest consumer of nonrenewable resources. Meanwhile, the unused materials are continually disposed in landfills and dumpsites. As a result, adoption of industrial solid wastes for use as a construction material remains pertinent in the creation of a green environment. The present study focused on the influence of EAF steel slag aggregate (SSA) sizes on the workability and durability of concrete. Concrete mixes in 1:2:4 ratios of ce...

  18. Experiment on crack strain of rubber aggregate concrete restrained by bedrock%岩基约束橡胶集料混凝土开裂应变试验

    王可良; 隋同波; 许尚杰; 刘玲

    2013-01-01

    Prevention of bedrock concrete cracking can improve the durability and operation safety of hydraulic structures.In this work,the cracking mechanism and restrained strain of rubber aggregate motar were studied through an experiment of restrained loop with resistance strain gauges,scanning electron microscrope and mercury porosimeter.The strain gauges were buried into bedrock concrete for measurement of restrained strain of rubber aggregate concrete.The results reveal that the rubber aggregate material under stressing causes a change in the shape of pores in the cement paste matrix and part of its stress is released.In the condition of ordinary motar cracking,this material develops curing strain and larger restrained strain,so the concrete does not crack.At the ages of 45d and 90d,the restrained strain in ordinary bedrock concrete is reduced quickly and its cracks start developing.Thus,rubber aggregate can improve the performances of bedrock concrete against cracking.This study provides an effective technical measure for prevention of bedrock concrete cracking.%解决岩基混凝土开裂有利于提高水工建筑物的耐久性和安全运行.采用约束圆环试验、电阻应变仪、电子扫描电镜和压汞试验,分析了橡胶集料砂浆约束开裂应变及其作用机理.在岩基混凝土内埋设应变计,观测橡胶集料混凝土的约束应变.结果表明:橡胶集料在应力作用下,改变了水泥石中孔的形态,缓冲部分应力,普通砂浆开裂时,橡胶集料开始表现硬化应变.在45d和90d龄期时,岩基普通混凝土应变急剧降低,混凝土出现开裂.岩基橡胶集料混凝土约束应变大,混凝土无开裂.橡胶集料有利于改善岩基混凝土的抗裂性能,为解决岩基混凝土裂缝提供一种新的技术措施.

  19. Lightweight concrete masonry units based on processed granulate of corn cob as aggregate

    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.

  20. Laboratory Investigation Of Partial Replacement Of Coarse Aggregate By Plastic Chips And Cement By Human Hair

    A.S.Balaji

    2014-04-01

    Full Text Available The use of plastic is increasing day by day, although steps were taken to reduce its consumption. The suitability of recycled plastics as coarse aggregate in concrete and its advantage are discussed here. Experimental investigation was done using M20 mix and tests were carried out as per recommended procedures by relevant codes. As 100% replacement of natural coarse aggregate (NCA with plastic coarse aggregate (PCA is not feasible, partial replacement were examined. And also Hair is used as a fibred reinforcing material in concrete as partial replacement of cement. It has a high tensile strength which is equal to that of a copper wire with similar diameter. It is also available in abundance and at a very low cost. Tests were conducted to determine the properties of plastic aggregate and human hair such as density, specific gravity and crushing value. Experiments were conducted on concrete cubes with various percentages of human hair i.e. 0%, 0.5%, 1%, 1.5%, 2%, and 3% by weight of cement and with constant percentage of plastic aggregate as 20%.

  1. Application of Base Force Element Method to Mesomechanics Analysis for Concrete

    2014-01-01

    The base force element method (BFEM) on damage mechanics is used to analyze the compressive strength, the size effects of compressive strength, and fracture process of concrete at mesolevel. The concrete is taken as three-phase composites consisting of coarse aggregate, hardened cement mortar, and interfacial transition zone (ITZ) on mesolevel. The random aggregate model is used to simulate the mesostructure of concrete. The mechanical properties and fracture process of concrete under uniaxia...

  2. Evaluation of corrosion effect in reinforced concrete by chloride exposure

    Loreto, G.; Di Benedetti, M.; Iovino, R.; Nanni, A.; Gonzalez, M. A.

    2011-04-01

    Durability is generally described as the ability of a material to maintain its physical and mechanical properties over time. In reinforced concrete (RC) structures, concrete is the ideal material to protect the steel reinforcement given its high alkalinity. In environments subjected to highly aggressive conditions, mostly due to the presence of chlorides, concrete may lose its protective characteristics and allow for accelerated ageing. Concrete degradation and steel reinforcement corrosion are phenomena closely connected. The aim of this research work is the characterization of the relationship between steel reinforcement corrosion and concrete degradation under accelerated ageing in a 3% sodium chloride solution. The method of linear polarization is used for identification of the corrosion rate of the steel bar. Additionally, the values of concrete residual strength are obtained, and correlated to both the corrosion rate and width of concrete cracks. Finally, the prediction of the concrete cover useful life is estimated.

  3. Use of Recycled Concrete Aggregate in Controlled Low-Strength Material (CLSM)

    Mustapha K.N.; Omar H.; Naganathan S.

    2012-01-01

    Use of recycled concrete aggregate (RCA) is getting importance as it minimizes the use of fresh materials and eliminates waste disposal. One of the uses of RCA is as aggregate in Controlled Low Strength Material (CLSM). This paper reports the results of the investigation done on the use of RCA in CLSM. Various mixtures of CLSM were made using RCA, fly ash, and cement. Tests for workability, bleeding, density, strength, water absorption, sorption, and ultrasonic pulse velocity (UPV) were condu...

  4. Exploratory Study of Rubber Seed Shell as Partial Coarse Aggregate Replacement in Concrete

    K. Muthusamy; Nordin, N.; G. Vesuvapateran; M. Ali; N.A. Mohd Annual; H. Harun; H. Ullap

    2014-01-01

    Malaysia being a major rubber trees growing country has been generating a large amount of rubber seed shell which regarded as waste. At the same time, the growing construction industry which boosts the concrete production trade has results in higher consumption of natural coarse aggregate which open the door for depletion of this material in future. This study focuses on investigating the possibility of integrating crushed rubber seed shell as partial coarse aggregate replacement material in ...

  5. Experimental research on early strength of recycled coarse aggregate concrete%再生粗骨料混凝土早期强度试验研究

    张兴才; 李洪明; 朱磊

    2015-01-01

    通过试验研究水灰比、再生粗骨料取代率和用水量对再生混凝土早期抗压强度和抗折强度的影响。研究结果表明,再生混凝土各龄期的强度系数随水灰比、骨料取代率、单位用水量等因素变化不大。再生混凝土的各个龄期的抗压和抗折强度均随水灰比和再生骨料取代率的增大而降低。根据试验结果建立了再生粗骨料取代率为100%的再生混凝土早期抗压强度和抗折强度计算模型,该模型计算结果与他人试验结果吻合较好。%The influences of water-cement ratio,replacement ratio of recycled coarse aggregate,and water amount on early compres-sive strength and flexural strength of recycled concrete were investigated by experiments. Research results show that the strength ratio of recycled coarse aggregate concrete didn′t vary with water-cement ratio,replacement ratio and water amount,the compressive strength and flexural strength at different ages decrease with the water-cement ratio and replacement ratio. The models for early compressive strength and flexural strength of recycled concrete with 100% replacement of recycled coarse aggregate are established according to ex-periment results,and the calculated values of the strength of recycled coarse aggregate concrete are in good agreement with the test val-ues obtained by other researchers.

  6. Local damage to Ultra High Performance Concrete structures caused by an impact of aircraft engine missiles

    Riedel, Werner [Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institute, Eckerstrasse 4, D-79104 Freiburg (Germany); Noeldgen, Markus, E-mail: mnoeldgen@schuessler-plan.d [Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institute, Eckerstrasse 4, D-79104 Freiburg (Germany); Schuessler-Plan Engineering Ltd., St.-Franziskus-Str. 148, D-40470 Duesseldorf (Germany); Strassburger, Elmar; Thoma, Klaus [Fraunhofer Institute for High-Speed Dynamics, Ernst-Mach-Institute, Eckerstrasse 4, D-79104 Freiburg (Germany); Fehling, Ekkehard [University of Kassel, Chair of Structural Concrete, Kurt-Wolters Str. 3, D-34109 Kassel (Germany)

    2010-10-15

    Research highlights: {yields} Experimental series on UHPC panels subjected to aircraft engine impact. {yields} Improved ballistic limit of fiber reinforced UHPC in comparison to conventional R/C. {yields} Detailed investigation of failure mechanisms of fiber reinforced UHPC panel. - Abstract: The impact of an aircraft engine missile causes high stresses, deformations and a severe local damage to conventional reinforced concrete. As a consequence the design of R/C protective structural elements results in components with rather large dimensions. Fiber reinforced Ultra High Performance Concrete (UHPC) is a concrete based material which combines ultra high strength, high packing density and an improved ductility with a significantly increased energy dissipation capacity due to the addition of fiber reinforcement. With those attributes the material is potentially suitable for improved protective structural elements with a reduced need for material resources. The presented paper reports on an experimental series of scaled aircraft engine impact tests with reinforced UHPC panels. The investigations are focused on the material behavior and the damage intensity in comparison to conventional concrete. The fundamental work of is taken as reference for the evaluation of the results. The impactor model of a Phantom F4 GE-J79 engine developed and validated by Sugano et al. is used as defined in the original work. In order to achieve best comparability, the experimental configuration and method are adapted for the UHPC experiments. With 'penetration', 'scabbing' and 'perforation' all relevant damage modes defined in are investigated so that a full set of results are provided for a representative UHPC structural configuration.

  7. Local damage to Ultra High Performance Concrete structures caused by an impact of aircraft engine missiles

    Research highlights: → Experimental series on UHPC panels subjected to aircraft engine impact. → Improved ballistic limit of fiber reinforced UHPC in comparison to conventional R/C. → Detailed investigation of failure mechanisms of fiber reinforced UHPC panel. - Abstract: The impact of an aircraft engine missile causes high stresses, deformations and a severe local damage to conventional reinforced concrete. As a consequence the design of R/C protective structural elements results in components with rather large dimensions. Fiber reinforced Ultra High Performance Concrete (UHPC) is a concrete based material which combines ultra high strength, high packing density and an improved ductility with a significantly increased energy dissipation capacity due to the addition of fiber reinforcement. With those attributes the material is potentially suitable for improved protective structural elements with a reduced need for material resources. The presented paper reports on an experimental series of scaled aircraft engine impact tests with reinforced UHPC panels. The investigations are focused on the material behavior and the damage intensity in comparison to conventional concrete. The fundamental work of is taken as reference for the evaluation of the results. The impactor model of a Phantom F4 GE-J79 engine developed and validated by Sugano et al. is used as defined in the original work. In order to achieve best comparability, the experimental configuration and method are adapted for the UHPC experiments. With 'penetration', 'scabbing' and 'perforation' all relevant damage modes defined in are investigated so that a full set of results are provided for a representative UHPC structural configuration.

  8. Development of high-performance concrete having high resistance to chloride penetration

    The resistance to chloride penetration is one of the simplest measures to determine the durability of concrete, e.g. resistance to freezing and thawing, corrosion of steel in concrete and other chemical attacks. Thus, high-performance concrete may be defined as the concrete having high resistance to chloride penetration as well as high strength. The purpose of this paper is to investigate the resistance to chloride penetration of different types of concrete and to develop high-performance concrete that has very high resistance to chloride penetration, and thus, can guarantee high durability. A large number of concrete specimens have been tested by the rapid chloride permeability test method as designated in AASHTO T 277 and ASTM C 1202. The major test variables include water-to-binder ratios, type of cement, type and amount of mineral admixtures (silica fume, fly ash and blast-furnace slag), maximum size of aggregates and air-entrainment. Test results show that concrete containing optimal amount of silica fume shows very high resistance to chloride penetration, and high-performance concrete developed in this study can be efficiently employed to enhance the durability of concrete structures in severe environments such as nuclear power plants, water-retaining structures and other offshore structures

  9. EXPERIMENTAL STUDY ON BEHAVIOUR OF CONCRETE USING SELF CURING AGENTS

    M.Srihari, B.Karthick

    2016-01-01

    Concrete is most widely used construction material due to its good compressive strength and durability. Depending upon the nature of work, the constituent materials; cement, fine aggregate, coarse aggregate and water are mixed in specific proportions to produce concrete. Concrete needs congenial atmosphere by providing moisture for a minimum period of 28 days for good hydration and to attain desired strength. Any laxity in curing will badly affect the strength and durability of concrete. Self...

  10. Research on carbonation resistance of recycled aggregate concrete%再生混凝土抗碳化性能研究

    黄秀亮; 王成刚; 柳炳康

    2013-01-01

    再生混凝土的碳化性能与再生集料来源、矿物掺和料、试验方法等因素有关,不同研究者的试验结果往往具有较大的离散性。文章通过再生混凝土的快速碳化试验,主要研究不同粉煤灰取代率、水胶比对再生混凝土抗碳化性能的影响,对比了再生混凝土与普通混凝土的抗碳化性能;并用灰色关联理论对影响再生混凝土的因素作了分析,得到了与定性分析相一致的结论。%The performance of recycled aggregate concrete is related with the sources of recycled aggre-gate ,mineral admixtures and test methods ,so there are many different research results .Through the rapid carbonization test on recycled concrete ,the influence of different water-cement ratio and fly ash replacement ratio on the carbonization resistance of recycled concrete is studied ,and the carbonization resistance of ordinary concrete and recycled concrete is compared .The grey relation theory is used to analyze the influential factors of the recycled concrete ,and the results are consistent with those ob-tained by traditional mathematical statistics method .

  11. Relationship between pore structure and compressive strength of concrete: Experiments and statistical modeling

    J BU; Z TIAN

    2016-03-01

    Properties of concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the pore structure-compressive strength relationship in concrete. Several concrete mixtures with different pore structures are proportioned and subjected to static compressive tests. The pore structure features such as porosity, pore size distribution are extracted using mercury intrusion porosimetry technique. A statistical model is developed to relate thecompressive strength to relevant pore structure features.

  12. Load-carrying capacity of lightly reinforced, prefabricated walls of lightweight aggregate concrete with open structure

    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 of the...

  13. Inspection of reinforced concrete samples by Compton backscattering technique

    Boldo, E. M.; Appoloni, C. R.

    2014-02-01

    Reinforced concrete structures require frequent monitoring to ensure the concrete quality during its service life and for evaluation of in situ existing conditions. Compton backscattering of gamma rays is a nondestructive technique used for material characterization and detection of defects and inclusions in materials and can be employed on reinforced concrete. The methodology allows one-sided inspection of large structures, is relatively inexpensive and can be portable. The concept is based on detection of backscattered radiation produced from a collimated beam aimed at the sample. By measuring the spectrum of these scattered gamma rays it is possible to determine local density perturbations. In this work we used the Compton backscattering technique to locate and measure steel, defects and crushed stone inside concrete. The samples were irradiated with gamma rays from a Ø2 mm diameter collimated 241Am (100 mCi) source and the inelastically scattered photons were recorded at an angle of 135° by a high resolution CdTe semiconductor detector. Scanning was achieved by lateral movement of the sample blocks across the source and detector field of view in steps of 1 mm. A previous optimization of the experimental setup was performed with Monte Carlo simulation. The results showed that it was possible to locate inclusions and defects with Ø8 mm positioned at a depth of 20 mm below the surface of the sample. It was observed that aggregates such as crushed stone could mask defects at specific points due to high attenuation of the incident and scattered beam.

  14. Experimental Investigation of Use of Microsilica in Self Compacting Concrete

    Mr.Ashok P. Kalbande; Prof. R.V.R.K. Prasad

    2012-01-01

    This paper is described Project in detail and presents laboratory observation. Microsilica is used as a 10% replacement of cement by weight. Various test were conducted on fine aggregate & coarse aggregate, to determine specific gravity, bulk density, fineness modulus of aggregate, concrete mix proportion design using this parameter..For conventional concrete water cement ratio of 0.4 and for microsilica concrete is increased water contain about 20liter/m3. Water demand increases in ...

  15. Dynamic testing of concrete under high confined pressure. Influence of saturation ratio and aggregate size

    Forquin, P.; Piotrowska, E.; Gary, G.

    2015-09-01

    Concrete structures can be exposed to intense pressure loadings such as projectile-impact or detonation near a concrete structural element. To investigate the mechanical behaviour of concrete under high confining pressure, dynamic quasi-oedometric compression tests have been performed with a large diameter (80 mm) Split Hopkinson Pressure Bar apparatus. The concrete sample is placed within a steel confining ring and compressed along its axial direction. Hydrostatic pressures as high as 800 MPa and axial strain of about - 10% are reached during the tests. In the present work, experiments have been conducted on two types of concrete: MB50 microconcrete with a maximum grain size of 2 mm and R30A7 ordinary concrete of maximum grain size about 8 mm. Both concretes are tested in dry or saturated conditions. According to these dynamic experiments it is noted that grain size has a small influence whereas water content has a strong effect on the confined behaviour of concrete.

  16. Compressive behaviour of a tire recycled steel and textil fiber concrete subjected to fire

    Santos, C.C.; Rodrigues, J. P.

    2015-01-01

    The use of rubber aggregates, steel and textile fibres recycled from tires in concrete is a solution that it is being studied by several authors around the world. A few works have been carried out at room temperature but very scarce at high temperatures. This paper presents the results of a research with the aim to evaluate the behaviour at high temperatures of a concrete made with different amounts of recycled textile and steel fibres from tires. The study considered five conc...

  17. Relationship Between Water-Stable Aggregates and Nutrients in Black Soils After Reclamation

    MA Qiang; YU Wan-Tai; ZHAO Shao-Hua; ZHANG Lu

    2007-01-01

    Water-stable aggregates, which are an index for the evaluation of the structural properties of the soil, are affected by many factors. Zhaoguang Farm, Longzhen Farm, and Jiusan Farm were chosen as the representative study sites in the region of black soils, a typical soil resource in Northeast China. The variation in the content of>0.25 mm water-stable aggregates and its relationship with the nutrients in black soil were investigated after different years of reclamation. The results showed that the>0.25 mm water-stable aggregates were more in the surface than in the subsurface soil and they changed in the following order: Longzhen Farm>Zhaoguang Farm>Jiusan Farm. The water-stable aggregates decreased sharply at the initial stage of reclamation and then became stable gradually with time. They were significantly correlated with the contents of organic C, total N, total P, and CEC in black soil, with the correlation coefficients r being 0.76, 0.68, 0.61, and 0.81 (P<0.01), respectively; however, their relationships with available P, available K, and total K were unclear. These showed that organic matter was the cementation of soil water-stable aggregates. Increasing decompositions and decreasing inputs of organic matter after reclamation were responsible for the amount of reduction of the water-stable aggregates. Thus, to maintain good soil aggregate structure, attention should be paid to improvement of soil nutrient status, especially the supply of organic C and N.

  18. Study about the capillary absorption and the sorptivity of concretes with Cuban limestone aggregates

    Howland, J. J.

    2013-12-01

    Full Text Available The objective of this study was to demonstrate the possibility to obtain concretes in Cuba with values of effective porosity below of 10%, using limestone aggregates with high levels of absorption (higher than 1% in many cases, and values of Sorptivity below of 5 x 10-5 m/s1/2 as is established in the document prepared by the DURAR Latin Working Group, for structures exposed to very aggressive environments. The experimental results showed that the use of the trial method of capillary absorption of Göran Fagerlund, were obtained concretes with effective porosity below of the 10%, for water/cement ratios of 0.4 and 0.45, but the values of sorptivities were very high. Nevertheless the subsequent use of the trial method of the ASTM C1585, that use cylinders probes with bigger depth and different processing, permits to obtain the desired sorptivity values for water/cement ratios of 0.4 and 0.45 whenever would be fulfilled the Good Practices of the Construction.El objetivo del estudio fue demostrar la posibilidad de lograr en Cuba, con el empleo de áridos calizos de elevada absorción (mayores del 1% en muchos casos, hormigones con valores de porosidad efectiva inferiores al 10% y de velocidad de absorción capilar (Sorptividad inferiores a 5 x 10-5 m/s1/2, tal como establece el documento elaborado por la RED DURAR del CYTED para estructuras expuestas a ambientes muy agresivos. Los resultados experimentales mostraron que con la aplicación del método de ensayo de absorción capilar de Göran Fagerlund se obtuvieron porosidades efectivas inferiores al 10% para relaciones agua/cemento de 0,4 y 0,45, pero los valores de sorptividad fueron muy elevados. No obstante la aplicación posterior del método de ensayo de la ASTM C1585 que utiliza probetas de mayor espesor y diferente tratamiento, permitió obtener los valores indicados de sorptividad para relaciones agua/cemento de 0,4; 0,45 siempre que se cumplan las Buenas Prácticas constructivas.

  19. Effects of extraction methods and factors on leaching of metals from recycled concrete aggregates.

    Bestgen, Janile O; Cetin, Bora; Tanyu, Burak F

    2016-07-01

    Leaching of metals (calcium (Ca), chromium (Cr), copper, (Cu), iron (Fe), and zinc (Zn)) of recycled concrete aggregates (RCAs) were investigated with four different leachate extraction methods (batch water leach tests (WLTs), toxicity leaching procedure test (TCLP), synthetic precipitation leaching procedure test (SPLP), and pH-dependent leach tests). WLTs were also used to perform a parametric study to evaluate factors including (i) effects of reaction time, (ii) atmosphere, (iii) liquid-to-solid (L/S) ratio, and (iv) particle size of RCA. The results from WLTs showed that reaction time and exposure to atmosphere had impact on leaching behavior of metals. An increase in L/S ratio decreased the effluent pH and all metal concentrations. Particle size of the RCA had impact on some metals but not all. Comparison of the leached concentrations of metals from select RCA samples with WLT method to leached concentrations from TCLP and SPLP methods revealed significant differences. For the same RCA samples, the highest metal concentrations were obtained with TCLP method, followed by WLT and SPLP methods. However, in all tests, the concentrations of all four (Cr, Cu, Fe, and Zn) metals were below the regulatory limits determined by EPA MCLs in all tests with few exceptions. pH-dependent batch water leach tests revealed that leaching pattern for Ca is more cationic whereas for other metals showed more amphoteric. The results obtained from the pH-dependent tests were evaluated with geochemical modeling (MINTEQA2) to estimate the governing leaching mechanisms for different metals. The results indicated that the releases of the elements were solubility-controlled except Cr. PMID:26996910

  20. Application of Coconut Shell as Coarse Aggregate in Concrete: A Technical Review

    Parag S. Kambli

    2014-03-01

    Full Text Available Oil palm shell (OPS is a waste from the agricultural sector and is available in large quantities in the tropical regions. The high cost of conventional building materials is a major factor affecting housing delivery in world. This has necessitated research into alternative materials of construction. The project paper aims at analysing compressive strength characteristics of concrete produced using crushed, granular coconut as substitutes for conventional coarse aggregate with partial replacement. The main objective is to encourage the use of these ‘seemingly’ waste products as construction materials in low-cost housing. It is also expected to serve the purpose of encouraging housing developers in investing these materials in house construction.

  1. Introduction to concrete curing effect on the early performance of modern concrete

    Xiaoxia Zhai

    2015-08-01

    Full Text Available In order to meet the requirements of the modern structure of concrete performance, the composition of modern concrete produced bigger change, this inevitably made an impact on the other properties of concrete. Especially the change of cement fineness and composition, a large number of add mineral admixtures, and the widespread use of high efficiency water reducing agent, has a great influence on the early performance of concrete, especially on the early shrinkage performance, which affect the early cracking of concrete. By collecting and analysising relevant test result, The article summarizes the characteristics of the early performance of modern concrete and their requirements of early curing environment.

  2. 流态轻集料微孔混凝土的试验研究%Experimental Research of Fluid Lightweight Aggregate Micro Foam Concrete

    王洪镇; 杨俊晓

    2011-01-01

    利用复合快硬水泥、水渣等轻集料和高效微泡剂等外加剂,配制出了高性能的新型轻质混凝土;通过对原材料和混凝土的试验分析及与普通轻集料混凝土、泡沫混凝土的性能比较,结合微观机理的分析研究,阐述了该新型混凝土的性能特征.%The combined rapid hardening cement,water quenched slag, lightweight materials and efficient micro-bubble additive were used to prepare a new type of high-performance lightweight concrete. Through the analysis of the test results of raw materials and concrete and by comparison with ordinary light aggregate concrete and foam concrete performance, with the aid of the analysis of the micro-mechanism studies, .the performance characteristics of the new type of concrete was elucidated.

  3. Sequestration of CO2 by concrete carbonation.

    Galan, Isabel; Andrade, Carmen; Mora, Pedro; Sanjuan, Miguel A

    2010-04-15

    Carbonation of reinforced concrete is one of the causes of corrosion, but it is also a way to sequester CO2. The characteristics of the concrete cover should ensure alkaline protection for the steel bars but should also be able to combine CO2 to a certain depth. This work attempts to advance the knowledge of the carbon footprint of cement. As it is one of the most commonly used materials worldwide, it is very important to assess its impact on the environment. In order to quantify the capacity of cement based materials to combine CO2 by means of the reaction with hydrated phases to produce calcium carbonate, Thermogravimetry and the phenolphthalein indicator have been used to characterize several cement pastes and concretes exposed to different environments. The combined effect of the main variables involved in this process is discussed. The moisture content of the concrete seems to be the most influential parameter. PMID:20225850

  4. The Relationship between Rebar-Debonding and Cracking in Reinforced Concrete

    Thybo, Anna Emilie A.; Stang, Henrik; Olesen, John Forbes

    2012-01-01

    A mechanical model has been used to evaluate the rebar-concrete debonding length and Crack Mouth Opening Displacement (CMOD) in reinforced concrete. The modelling is based on the theory of the fictitious crack. It is shown that there is a non-trival relationship between the debonding length and the...

  5. The exploration study of fire damage to concrete specimen using x-ray computed tomography

    Su, Yu-Min; Lee, Min-Gin; Chen, Guan-Ying

    2015-04-01

    Portland Cement Concrete (PCC) loses the evaporable water at about 100 °C, decomposes C-S-H at about 200 °C, and dehydrates CH at about 500 °C, and deconstruct C-S-H at about 900°C. The concrete degradation or cracks are caused by several possible parameters, such as vapor pressure in pores, thermal gradient, and varied expansion rates of cement pastes and aggregates. The objective of the exploration study was to assess the porosity before and after conditioning of high temperature in the laboratory with the medical X-ray computed tomography. The experimental program was determined to identify the mineral properties of the aggregates used and determine the consensus properties of compressive, splitting tensile, and flexural strengths. Concrete cylinders were subject with one temperature conditioning, namely 400°C, but two different heat conditioning time namely four and eight hours. The X-ray CT, before and after high temperature conditioning, was administrated on the concrete cylinders to inspect the depth of the damage zone, which shall consist of more porosity than undamaged one. The damage zone will be examined and identified through the changes in porosity of concrete paste and aggregates within a concrete cylinder. The significance of the exploration study was to provide an in-depth insight to define the damaged zone for a better understanding of the following repairing and reinforced work.

  6. Desempenho de concretos com agregados reciclados de cerâmica vermelha Performance of red ceramic recycled aggregate concrete

    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.

  7. Effect of Gradation Optimization of Aggregate on Binder Content in Concrete%骨料级配优化对混凝土胶凝材料用量的影响

    蔡杰龙; 杨永民; 李伟

    2014-01-01

    骨料级配优化对于改善混凝土工作性能和节省胶凝材料用量具有重要的意义。该文分别对粗细骨料级配进行优化得到堆积密度大、空隙率小的细骨料和粗骨料,并分2种类型(直卸、泵送)和3种标号( C20、 C25、 C30)进行混凝土配合比试验对比骨料级配优化前后单方混凝土胶凝材料用量,最后通过实例进行验算。试验结果表明,当砂中0.315 mm以下细砂含量控制在一定比例,并在连续级配的5~31.5 mm碎石或5~25 mm碎石中掺入一定比例的5~10 mm石时,每m3混凝土中胶凝材料用量均可得到一定程度的降低,与理论验算结果较为吻合。骨料级配优化可操作性强,适合在混凝土生产企业中推广。%Aggregate Gradation optimization is of great importance in improving the working performance of concrete and saving binder content.In this article, gradation of coarse aggregate and fine aggregate is respectively optimized to obtain the aggregate with higher bulk density and lower voidage .Then design mix of concrete experiments on two kinds of concrete ( field concrete , pump concrete) and three kinds of grades(C20, C25, C30) are carried out to compared the binder content in an unit of concrete before and after gradation of aggregate is optimized .Finally, checking computations is implemented by example .It is shown that the binder content in an unit of concrete gets an certain degree of reduction if the ratio of fine sand (≤0.315mm) in fine aggregate is proper and a certain proportion of 5 ~10mm gravel is mixed into 5 ~31.5mm or 5 ~25mm gravel.And the result accords with the theoretical checking computations .Gradation optimization of aggregate is easily operability and suitable for promotion in concrete manufacturing enterprise .

  8. Relationship between permeability and damage in concretes at high temperature

    Due to its technical and economical advantages, concrete is nowadays the most used building material in civil engineering. Even if its use is known since nearly two centuries, its behavior has not been yet completely explained due to the complexity of its porous microstructure. This fact is quite evident under particular conditions such as, by instance, during an elevation of temperature. This condition can mainly occur in two cases: due to a casualty (e.g. a fire) or in normal use conditions (e.g. storage of nuclear rejects). This work aims at contributing to the study of the phenomena that can be observed in concrete exposed to high temperatures and, in particular, focuses on the study of the evolution of intrinsic permeability. The characterisation of permeability (which is hardly measurable in hot conditions) is necessary for describing and modelling transport phenomena which occur in porous media. An experimental study has been made in collaboration with the CEA. A real-scale hollow cylinder has been instrumented with gauges for studying the evolution of temperature and gas pressure fields inside concrete. Later, the cylinder has been then numerically modelled by means of a thermo-hydro-chemical (THC) and a thermo-hydro-chemo-mechanical (THCM) model. The THC model, implemented by means of the finite volume method, has allowed a first, qualitative study of the behaviour of concrete submitted to high temperature. This model, which, for sake of simplicity, has neglected all mechanical effects, has allowed the description of the main phenomena occurring inside concrete: mass transport, phase changes, microstructure evolution. Later, the modelling has been completed by means of the THCM model using the Hitecosp code, implemented by means of the finite element method at the university of Padua. This code allows a very complete description of the phenomena occurring inside concrete and takes into consideration the mechanical behavior of concrete by means of an

  9. Assessment of Concrete Strength Using Partial Replacement of Coarse Aggregate for Wast Tiles and Cement for Rice Husk Ash in Concrete

    Umapathy U

    2014-05-01

    Full Text Available Conservation of natural resources and preservation of environment is the essence of any development. The problem arising from continuous technological and industrial development is the disposal of waste material. If some of the waste materials are found suitable in concrete making, not only cost of construction can be cut down, but also safe disposal of waste materials can be achieved. So in our project, an attempt has been made to assess the suitability of stone with waste tills in concrete making. In the laboratory tiles has been tried as coarse aggregate has been used as partial substitute to conventional coarse aggregate concrete making and today many researches are ongoing into the use of Portland cement replacements, using many waste materials like pulverized fly ash (PFA and ground granulated blast furnace slag (GGBS. Like PFA and GGBS a waste glass powder (GLP is also used as a binder with partial replacement of cement which takes some part of reaction at the time of hydration. In this study, rice husk ash have been used as partially replacements to the cement Cubes were cast and tested for compressive strength, and modulus of rupture after a curing period of 7,17,28 days.

  10. Influence of added concrete compressive strength on adhesion to an existing concrete substrate

    Júlio, Eduardo N. B. S.; Branco, Fernando A. B.; Silva, Vítor D.; Lourenço, Jorge F.

    2006-01-01

    An experimental study was performed to evaluate the bond strength between two concrete layers of different ages, considering different mixtures of added concrete, with different strengths. The specimens first had the roughness of the substrate surface increased by sand blasting. Later, the new concrete was added. Afterwards, slant shear tests were performed to quantify the bond strength in shear. These tests indicated that increasing the compressive strength of the added concrete relative to ...

  11. Structural Lightweight Concrete Production by Using Oil Palm Shell

    Habibur Rahman Sobuz; Noor Md. Sadiqul Hasan; Nafisa Tamanna; Md. Saiful Islam

    2014-01-01

    Conventional building materials are widely used in a developing country like Malaysia. This type of material is costly. Oil palm shell (OPS) is a type of farming solid waste in the tropical region. This paper aims to investigate strength characteristics and cost analysis of concrete produced using the gradation of OPS 0–50% on conventional coarse aggregate with the mix proportions 1 : 1.65 : 2.45, 1 : 2.5 : 3.3, and 1 : 3.3 : 4.2 by the weight of ordinary Portland cement, river sand, crushed ...

  12. Organisms adaptable concrete. Eco-concrete for fresh water area; Seibutsu to kyoseisuru eco-concrete. Tansuiiki taiogata eco-concrete

    Sakai, k. [Hokkaido Development Bureau, Hokkaido Development Agency, Sapporo (Japan); Shindo, K. [Kyowa Concrete Industry Co. Ltd., Sapporo (Japan)

    1998-03-01

    Described herein are the current statuses of organisms in fresh water and organisms adaptable concrete for fresh water use, and results of the tests in which cylindrical blocks of porous concrete are placed in fresh water to follow types of organisms clinging to them and temporal changes in their numbers. These tests have confirmed that porous concrete can be used as the one compatible with the environment, because large quantities of aqueous insects and algae are found to cling to these blocks. The major findings are: larger quantities of aqueous insects cling to porous concrete than to ordinary one, and sometimes than to natural river floors; no effect of concrete composition on algae clinging thereto is observed; types of algae clinging to porous concrete are diversified with time; and it is possible to minimize changes in natural environments by replacing ordinary concrete by porous one. 6 refs., 10 figs.

  13. Porous Network Concrete: a bio-inspired building component to make concrete structures self-healing

    Sangadji, S.

    2015-01-01

    The high energy consumption, its corresponding emission of CO2 and financial losses due to premature failure are the pressing sustainability issues which must be tackled by the concrete infrastructure industry. Enhancement of concrete materials and durability of structures (designing new infrastructures for longer service life) is one solution to overcome the dilemma. Concrete is a quasi-brittle material with properties that are high in compression but weak in tension, therefor concrete is pr...

  14. Inspection of reinforced concrete samples by Compton backscattering technique

    Reinforced concrete structures require frequent monitoring to ensure the concrete quality during its service life and for evaluation of in situ existing conditions. Compton backscattering of gamma rays is a nondestructive technique used for material characterization and detection of defects and inclusions in materials and can be employed on reinforced concrete. The methodology allows one-sided inspection of large structures, is relatively inexpensive and can be portable. The concept is based on detection of backscattered radiation produced from a collimated beam aimed at the sample. By measuring the spectrum of these scattered gamma rays it is possible to determine local density perturbations. In this work we used the Compton backscattering technique to locate and measure steel, defects and crushed stone inside concrete. The samples were irradiated with gamma rays from a Ø2 mm diameter collimated 241Am (100 mCi) source and the inelastically scattered photons were recorded at an angle of 135° by a high resolution CdTe semiconductor detector. Scanning was achieved by lateral movement of the sample blocks across the source and detector field of view in steps of 1 mm. A previous optimization of the experimental setup was performed with Monte Carlo simulation. The results showed that it was possible to locate inclusions and defects with Ø8 mm positioned at a depth of 20 mm below the surface of the sample. It was observed that aggregates such as crushed stone could mask defects at specific points due to high attenuation of the incident and scattered beam. - Highlights: ► Compton Backscattering was used to inspect reinforced concrete samples. ► The positioning of rebars, defects and crushed stone was achieved. ► High attenuation presented by crushed stone can mask defects at specific points

  15. Acoustic properties of porous concrete made from arlite and vermiculite lightweight aggregates

    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

  16. Design and performance of masonry mortars made with recycled concrete aggregates

    Frías, M.

    2009-07-01

    Full Text Available The present paper discusses the technical feasibility ofusing the fine fraction of recycled aggregate fromconcrete rubble to manufacture cement mortar andpossible conditions.An initial study of the chemical and physical-mechanicalcharacteristics of fines recycled from selected concreteshowed that their high absorptivity and high sulfatecontent compared to natural limestone sands were thelimiting factors to their in masonry mortars.As in the caseof structural concrete, a blend of recycled and naturalaggregate would appear to be suitable for masonrymortars.A study of the mix proportions and characteristics ofmortars made with recycled concrete aggregate showedthat up to 25% recycled aggregate can be used incement-based masonry mortars with no significant declinein performance and no new admixtures or higher cementcontent requires.El presente trabajo presenta y discute las condiciones de viabilidad técnica para la utilización de la fracción fina de áridos reciclados, procedentes de escombro de hormigón, en la fabricación de morteros de albañilería utilizando cemento como conglomerante.Inicialmente, se estudian las características químicas y físico- mecánicas de los áridos reciclados finos procedentes de hormigón seleccionado. Se concluye que las características limitantes del árido reciclado para su uso en morteros de albañilería resultan ser la alta absorción y el elevado contenido en sulfatos, en comparación con las arenas naturales de naturaleza caliza. De forma análoga a lo recomendado en el hormigón estructural, se apunta hacia la utilización de mezclas de áridos reciclados y naturales en la fabricación de morteros de albañilería.Del estudio de dosificaciones y caracterización de morteros, elaborados con áridos reciclados de hormigón, se establece que los morteros de albañilería base cemento pueden incorporar un 25% como máximo de árido reciclado sin evidenciar pérdidas significativas de prestaciones. Y, no

  17. A study of the coupling relationship between concrete surface temperature and concrete surface emissivity in natural conditions.

    Tang, Lin-Ling; Chen, Xiao-Ling; Wang, Jia-Ning; Zhao, Hong-Mei; Huang, Qi-Ting

    2014-07-01

    Land surface emissivity (LSE) has already been recognized as a crucial parameter for the determination of land surface temperature (LST). There is an ill-posed problem for the retrieval of LST and LSE. And laboratory-based emissivity is measured in natural constant conditions, which is limited in the application in thermal remote sensing. To solve the above problems, the coupling of LST and LSE is explored to eliminate temperature effects and improve the accuracy of LES. And then, the estimation accuracy of LST from passive remote sensing images will be improved. For different land surface materials, the coupling of land surface emissivity and land surface temperature is various. This paper focuses on studying concrete surface that is one of the typical man-made materials in urban. First the experiments of measuring concrete surface emissivity and concrete surface temperature in natural conditions are arranged reasonably and the suitable data are selected under ideal atmosphere conductions. Then to improve the determination accuracy of concrete surface emissivity, the algorithm worked on the computer of Fourier Transform Infrared Spectroradiometer (FTIR) has been improved by the most adapted temperature and emissivity separation algorithm. Finally the coupling of concrete surface temperature and concrete surface emissivity is analyzed and the coupling model of concrete surface temperature and concrete surface emissivity is established. The results show that there is a highest correlation coefficient between the second derivative of emissivity spectra and concrete surface temperature, and the correlation coefficient is -0.925 1. The best coupling model is the stepwise regression model, whose determination coefficient (R2) is 0.886. The determination coefficient (R2) is 0.905 and the root mean squares error (RMSE) is 0.292 1 in the validation of the model. The coupling model of concrete surface temperature and concrete surface emissivity under natural conditions

  18. Light absorption and scattering by aggregates: Application to black carbon and snow grains

    A geometric-optics surface-wave approach has been developed for the computation of light absorption and scattering by nonspherical particles for application to aggregates and snow grains with external and internal mixing structures. Aggregates with closed- (internal mixing) and open-cell configurations are constructed by means of stochastic procedures using homogeneous and core-shell spheres with smooth or rough surfaces as building blocks. The complex aggregate shape and composition can be accounted for by using the hit-and-miss Monte Carlo geometric photon tracing method. We develop an integral expression for diffraction by randomly oriented aggregates based on Babinet's principle and a photon-number weighted geometric cross section. With reference to surface-wave contributions originally developed for spheres, we introduce a nonspherical correction factor using a non-dimensional volume parameter such that it is 1 for spheres and 0 for elongated particles. The extinction efficiency, single-scattering albedo, and asymmetry factor results for randomly oriented columns and plates compare reasonably well with those determined from the finite-difference time domain (FDTD) and the discrete dipole approximation (DDA) computer codes for size parameters up to about 20. The present theoretical approach covers all size ranges and is particularly attractive from the perspective of efficient light absorption and scattering calculations for complex particle shape and inhomogeneous composition. We show that under the condition of equal volume and mass, the closed-cell configuration has larger absorption than its open-cell counterpart for both ballistic and diffusion-limited aggregates. Because of stronger absorption in the closed-cell case, most of the scattered energy is confined to forward directions, leading to a larger asymmetry factor than the open-cell case. Additionally, light absorption for randomly oriented snowflakes is similar to that of their spherical counterparts

  19. New photo-thermal-synthesized polymer for self-compacting concrete to increase productivity, minimize pollution,and eliminate steam curing in precast concrete

    F. C.Lai; M. F.Mohd Zain; WANG Bao-min; K. C. Lee

    2006-01-01

    The objective in this study is to apply the sustainable chemistry and photo-thermal synthesis technology to produce the sustainable eco-superplasticiser for the sustainable high performance SCC concrete especially in hot tropical countries. A photo-thermal synthesized eco-superplasticiser (PSES) was produced by using photo-thermal catalyst in a solar chemical reactor. In this preliminary study, an unique high early strength of SCC concrete has been successfully produced by imposing an unique proportion of the photo-thermal-synthesized ecoSuperplasticiser (PSES), local fly ash, sand and aggregate. The SCC concrete is preliminary tried in the precast concrete product to produce the complicated geometries as Tunnel segment, U-shape beam, and Box girder which have the critical reinforcement and thin section concrete. Surprisingly, this SCC provide the benefits as eliminating steaming energy, increased productivity, and minimize pollution. These unique properties of sustainable SCC concrete can not be achieved by the convention concrete by using ligno, naphthalene and melamine base superplasticiser. The synthesized sustainable eco-superplasticiser is a perfect choice to fully utilized the renewable energy and improve the concrete working environment.

  20. Application of Coconut Shell as Coarse Aggregate in Concrete: A Technical Review

    Parag S. Kambli; Sandhya R. Mathapati

    2014-01-01

    Oil palm shell (OPS) is a waste from the agricultural sector and is available in large quantities in the tropical regions. The high cost of conventional building materials is a major factor affecting housing delivery in world. This has necessitated research into alternative materials of construction. The project paper aims at analysing compressive strength characteristics of concrete produced using crushed, granular coconut as substitutes for conventional coarse aggregate with...