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Sample records for cellular concrete

  1. Radioactivity of cellular concrete

    International Nuclear Information System (INIS)

    The natural radioactivity of cellular concrete is discussed. Some data on the concentrations of 40K, 226Ra and 232Th in building materials in Poland are given. The results of dose rates measurements in living quarters as well as outside are presented. (A.S.)

  2. Increase in cellular concrete resistance to brittle fracture

    International Nuclear Information System (INIS)

    Considered are theoretical premises of decrease in cellular concrete resistance to brittle fracture at the expense of dispersed reinforcement. It is stated experimentally that the introduction of 3% asbestos fibers permits to increase the ultimate extensibility and strength during cellular concrete tension by 15-30% and to increase in unit rupture work 1.4-1.6 time more and therefore to decrease its brittleness

  3. Effects of remote drop and pumpdown placement on cellular concrete

    International Nuclear Information System (INIS)

    The hazards to the public posed by abandoned mine shafts are well documented. As private development encroaches on previously mined areas, the potential for fatalities and serious injuries from abandoned mine shafts increases. The US Bureau of Mines has conducted research into cellular concrete as a material for sealing these openings. The current work involves testing the characteristics of cellular concrete before and after it had been pumped or dropped from different heights into a simulated mine shaft. Cellular concrete was pumped vertically up to and subsequently dropped from heights of 18 and 37 m into concrete forms. Wet density measurements were made at multiple sampling points in the test circuit. Air content determinations and uniaxial compressive strength testing were conducted. Research results are discussed

  4. Porosity and Mechanical Strength of an Autoclaved Clayey Cellular Concrete

    Directory of Open Access Journals (Sweden)

    P. O. Guglielmi

    2010-01-01

    Full Text Available This paper investigates the porosity and the mechanical strength of an Autoclaved Clayey Cellular Concrete (ACCC with the binder produced with 75 wt% kaolinite clay and 25 wt% Portland cement. Aluminum powder was used as foaming agent, from 0.2 wt% to 0.8 wt%, producing specimens with different porosities. The results show that the specimens with higher content of aluminum presented pore coalescence, which can explain the lower porosity of these samples. The porosities obtained with the aluminum contents used in the study were high (approximately 80%, what accounts for the low mechanical strength of the investigated cellular concretes (maximum of 0.62 MPa. Nevertheless, comparing the results obtained in this study to the ones for low temperature clayey aerated concrete with similar compositions, it can be observed that autoclaving is effective for increasing the material mechanical strength.

  5. Cellular Concrete Bricks with Recycled Expanded Polystyrene Aggregate

    OpenAIRE

    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...

  6. Multiparameter structure optimization of the cellular silicate concrete

    Directory of Open Access Journals (Sweden)

    A.A. Bedarev

    2013-04-01

    Full Text Available Strengthening the concept of energy efficiency requires the development and implementation of high-performance wall materials. The most promising in this respect is the cellular silicate concrete (gas silicate, which properties are superior to other insulating building materials. However, production of gas silicate insulation purpose with medium density less than 300 kg/m3 poses a number of difficulties due to the nature of its structure. In this regard, the current task is to maintain the specified quality of concrete porous silica with a decrease in its average density. In the article this problem is solved by a multi-level optimization of the macro- and microstructure based on multi-rich (multiparameter mathematical model. Algorithm and the general structure of the model and the results of laboratory studies are given.

  7. The use of vulcanic glasses in cellular concrete

    Directory of Open Access Journals (Sweden)

    Alvarez, J. L.

    1996-12-01

    Full Text Available This paper covers studies made using different mixes for cellular concrete variating silica sand, vulcanic glass and aluminium powder contents. Studies on compressive strenght, dry density and X-ray diffraction are performed on autoclave cured cellular concrete, concluding that best results are attained when vulcanic glass contents reaches 50% of silica sand. When percentage of aluminium powder is diminished from 0.11% to 0.09%, alight increase in density, with noticiable growth of comprensive strength are observed.

    Se hace un estudio con diferentes mezclas, teniendo como variables la arena sílice, el vidrio volcánico y el polvo de aluminio. Al hormigón celular, una vez curado en autoclave, se le hace un estudio de resistencia a la compresión, densidad en estado seco y difracción de rayos X, llegándose a la conclusión de que los mejores resultados se obtienen cuando se emplea el vidrio volcánico al 50% en sustitución de la arena sílice. Cuando se disminuye el porcentaje de polvo de aluminio de 0,11% a 0,09%, se presenta un ligero aumento en la densidad, con un notable crecimiento de la resistencia a la compresión.

  8. Cellular Concrete Bricks with Recycled Expanded Polystyrene Aggregate

    Directory of Open Access Journals (Sweden)

    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.

  9. Leachate and radon production from fly ash autoclaved cellular concrete

    International Nuclear Information System (INIS)

    Environmental consequences and potential liabilities of autoclaved cellular concrete (ACC) use were assessed by aqueous leaching of crushed samples for metals and organic solvent extractions of solid ACC for polycyclic aromatic hydrocarbons (PAHs). Also, whole ACC blocks were tested for radon exhalation potential. Results show leachate concentrations were typically 10 times below, and always 100 times below the regulatory threshold of applicable drinking water standards. A Microtox bioassay procedure showed no toxic effects due to leached metals. Organic analysis of solvent extracts indicated no release of hazardous PAHs attributable to the fly ash ingredient of ACC. Measured rates of radon exhalation were too low to cause potentially dangerous buildups in confined air spaces. Fly ash ACC may be characterized as an environmentally green construction material based on these findings

  10. Response of MICROTOX organisms to leachates of autoclaved cellular concrete

    International Nuclear Information System (INIS)

    The MICROTOX bioassay, a toxicity test involving bioluminescent microorganisms, was conducted on aqueous leachates derived from a construction material made using coal fly ash as the key siliceous ingredient. The material is known as autoclaved cellular concrete (ACC). The test indicated an absence of toxic effects attributable to soluble species, which included the priority heavy metals in the filtered leachates. Toxic or inhibitive effects on the test bacteria were observed for the toxicity characteristic leaching procedure (TCLP) leachates, but this was probably due to acetic acid in the extractant rather than the solubilized metals. The ASTM (distilled-deionized water extractant) and simulated acid rain leachates, by comparison, produced a repeatable stimulative effect. Stimulation observed in the form of enhanced light output may be a manifestation of hormesis, a phenomenon reportedly caused by exposure to extremely low concentrations (part-per-billion range) of otherwise toxic agents such as heavy metals

  11. Response of MICROTOX organisms to leachates of autoclaved cellular concrete

    Energy Technology Data Exchange (ETDEWEB)

    Latona, M.C.; Neufeld, R.D.; Hu, W.; Kelly, C.; Vallejo, L.E. [Univ. of Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering

    1997-08-01

    The MICROTOX bioassay, a toxicity test involving bioluminescent microorganisms, was conducted on aqueous leachates derived from a construction material made using coal fly ash as the key siliceous ingredient. The material is known as autoclaved cellular concrete (ACC). The test indicated an absence of toxic effects attributable to soluble species, which included the priority heavy metals in the filtered leachates. Toxic or inhibitive effects on the test bacteria were observed for the toxicity characteristic leaching procedure (TCLP) leachates, but this was probably due to acetic acid in the extractant rather than the solubilized metals. The ASTM (distilled-deionized water extractant) and simulated acid rain leachates, by comparison, produced a repeatable stimulative effect. Stimulation observed in the form of enhanced light output may be a manifestation of hormesis, a phenomenon reportedly caused by exposure to extremely low concentrations (part-per-billion range) of otherwise toxic agents such as heavy metals.

  12. Properties of high fly ash content cellular concrete

    Energy Technology Data Exchange (ETDEWEB)

    Neufeld, R.D.; Vallejo, L.E.; Hu, W.; Latona, M.; Carson, C.; Kelly, C. (Univ. of Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering)

    1994-04-01

    High fly ash content autoclaved cellular concrete is produced by adding calibrated quantities of aluminum powder to a mixture of fly ash (60% wt/wt), cement, and water. The foamed product is hardened in an autoclave with pressurized steam at about 180 C. Block material for samples tested originated from a mobile pilot plant that toured sites of United States-based electric utilities. Compressive strengths of the foamed product were controlled to the range of 300--600 psi, with dry weight densities on the order of 32--37 lb/cu ft. Heavy metal concentrations in TCLP, ASTM, and synthetic acid rain leachates were on the order one to 10 times that found in Pittsburgh tap water, and never approached 100 times drinking water standards. Organic contents of leachates were not detectable. Controlling pore distributions appears to influence density, moisture accumulation rates, and mechanical/physical properties that are significant for construction.

  13. Leachate and radon production from fly ash autoclaved cellular concrete

    Energy Technology Data Exchange (ETDEWEB)

    Latona, M.C.; Neufeld, R.D.; Vallejo, L.E.; Brandon, D.; Hu, W.; Kelly, C. [Univ. of Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering

    1997-08-01

    Environmental consequences and potential liabilities of autoclaved cellular concrete (ACC) use were assessed by aqueous leaching of crushed samples for metals and organic solvent extractions of solid ACC for polycyclic aromatic hydrocarbons (PAHs). Also, whole ACC blocks were tested for radon exhalation potential. Results show leachate concentrations were typically 10 times below, and always 100 times below the regulatory threshold of applicable drinking water standards. A Microtox bioassay procedure showed no toxic effects due to leached metals. Organic analysis of solvent extracts indicated no release of hazardous PAHs attributable to the fly ash ingredient of ACC. Measured rates of radon exhalation were too low to cause potentially dangerous buildups in confined air spaces. Fly ash ACC may be characterized as an environmentally green construction material based on these findings.

  14. Cellular concrete: a potential load-bearing insulation for cryogenic applications

    International Nuclear Information System (INIS)

    The need for low cost, low thermal conductivity, high strength insulation suitable for cryogenic applications is becoming more evident. An investigation of the potential of cellular concretes to fulfill this function was initiated. A review of the thermal and mechanical characteristics of foamed plastics and cellular concrete is presented along with relative cost comparisons. Test data from preliminary investigations is presented to define the influence of material constituents, density, and temperature on the mechanical and thermal response of cellular concrete. Specimen densities range from 0.64 to 1.44 gr/cc. The influence of temperature variations from 220C to -1960C is reported for selected densities

  15. Natural radioactivity of fly ashes and cellular concretes manufactured from them

    International Nuclear Information System (INIS)

    In the cellular concrete industry the radioactivity of wastes re-utilized as raw materials, especially of fly ashes and manufactured from them concretes is regularly controlled. The total content of potassium, thorium and radium as well as independently only the content of radium is determined. It happens, that the fly ashes have too high total content of natural radioactive elements, by about 10%. On the other hand the cellular concretes always fulful the recommendations of suitable codes. A change of the coal delivers for power stations from which the fly ashes have an increased radioactivity when they are utilized for building materials manufacturing is stipulated. (author)

  16. Laboratory testing of a building envelope segment based on cellular concrete

    Science.gov (United States)

    Fořt, Jan; Pavlík, Zbyšek; Černý, Robert

    2016-07-01

    Hygrothermal performance of a building envelope based on cellular concrete blocks is studied in the paper. Simultaneously, the strain fields induced by the heat and moisture changes are monitored. The studied wall is exposed to the climatic load corresponding to the winter climatic conditions of the moderate year for Prague. The winter climatic exposure is chosen in order to simulate the critical conditions of the building structure from the point of view of material performance and temperature and humidity loading. The evaluation of hygrothermal performance of a researched wall is done on the basis of relative humidity and temperature profiles measured along the cross section of the cellular concrete blocks. Strain gauges are fixed on the wall surface in expected orientation of the blocks expansion. The obtained results show a good hygrothermal function of the analyzed cellular concrete wall and its insignificant strain.

  17. Properties of the wall structures made of autoclaved cellular concrete products on the polyurethane foam adhesive

    Directory of Open Access Journals (Sweden)

    A.S. Gorshkov

    2013-08-01

    Full Text Available The article presents information on a test experiment for the construction of masonry fragments made of autoclaved cellular concrete products (ААС blocks on the polyurethane adhesive and the ensuing structural, thermal and technological tests of this type of masonry in specialized laboratories and testing facilities. It is shown that the use of polyurethane foam adhesive to bond the concrete blocks in the masonry walls is technically and economically feasible. On the basis of the tests it was concluded that the laying of concrete blocks on the polyurethane adhesive may be used in the construction of non-load bearing interior and exterior walls of buildings, including the filling of the external frame openings of monolithic buildings with floor bearing of the masonry on load bearing monolithic floors (with appropriate justification of the settlement.

  18. Partially rib precast and cast-in-situ floors with cellular-concrete blocks (rus

    Directory of Open Access Journals (Sweden)

    Gorshkov A.S.

    2011-10-01

    Full Text Available The object of research is precast and cast-in-situ inserted floor with cellular-concrete items used for reduction of structure weight. The used materials and installation technologies are considered.The aim of this work is analysis of strength and deformability of floor by two different methods: analytical calculation and calculation by finite element method using SCAD. It was shown that the finite element calculation is more precise and also it allows to use armature of lesser diameter that decreases the cost of the floor.For adjustment of given model and life duration of the structure the full-scale tests are necessary.

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

    Directory of Open Access Journals (Sweden)

    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.

  20. Interface morphologic characteristics of articles in load-bearing autoclaved cellular concrete

    Energy Technology Data Exchange (ETDEWEB)

    Peng, S.; Wang, L. [China University of Mining and Technology (China)

    1999-06-01

    Using SEM-EDAX, the morphological characteristics within the interfacial zone between the fly ash particles and the lime-cement paste of load-bearing autoclaved cellular concrete is studied. The results shows that with autoclaved curing, the crystals of the hydration product are well developed. The microstructure of the interlocking needle and fibre shaped hydration products is denser than that of natural curing. Under natural curing, the crystallization of the hydration product is low, the particles mainly present in piles. Irregular dispersed grain-shaped hydration products are seen on the breaking face in the early stage of curing. Rod and sheet shaped AFt, AFm phases are seen later. The lack of connecting and interlocking of the hydration products is the main reason for the low strength of natural curing product. 4 refs., 6 figs., 1 tab.

  1. Strength properties of autoclaved cellular concrete with high volume fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Hu, W.; Neufeld, R.D.; Vallejo, L.E.; Kelly, C.; Latona, M. [Univ. of Pittsburgh, PA (United States). Dept. of Civil and Environmental Engineering

    1997-08-01

    This paper presents the results of an investigation on the strength properties of autoclaved cellular concrete (ACC) blocks, a building material that can contain up to 70% w/w of electric utility fly ash. The scope of this investigation covers three phases: (1) a brief literature review; (2) a selection of optimum strength testing methods suitable for ACC materials; and (3) a determination of physical properties of ACC made with US electric utility fly ash, and comparison of such properties to European ACC materials made with sand as the silica source. Optimum laboratory testing methods were selected based on a comprehensive literature search that included American, European, and Chinese standards. The properties examined were compressive, tensile, and flexural strengths. Results showed that block recipe and density influence the compressive, tensile, and flexural strength values. The investigation indicated that the compressive strength of the blocks increases with dry weight density, and decreases as their moisture content increases.

  2. Cellular lightweight concrete containing high-calcium fly ash and natural zeolite

    Science.gov (United States)

    Jitchaiyaphum, Khamphee; Sinsiri, Theerawat; Jaturapitakkul, Chai; Chindaprasirt, Prinya

    2013-05-01

    Cellular lightweight concrete (CLC) with the controlled density of approximately 800 kg/m3 was made from a preformed foam, Type-I Portland cement (OPC), fly ash (FA), or natural zeolite (NZ), and its compressive strength, setting time, water absorption, and microstructure of were tested. High-calcium FA and NZ with the median particle sizes of 14.52 and 7.72 μm, respectively, were used to partially replace OPC at 0, 10wt%, 20wt%, and 30wt% of the binder (OPC and pozzolan admixture). A water-to-binder mass ratio (W/B) of 0.5 was used for all mixes. The testing results indicated that CLC containing 10wt% NZ had the highest compressive strength. The replacement of OPC with NZ decreased the total porosity and air void size but increased the capillary porosity of the CLC. The incorporation of a suitable amount of NZ decreased the setting time, total porosity, and pore size of the paste compared with the findings with the same amount of FA. The total porosity and cumulative pore volume decreased, whereas the gel and capillary pores increased as a result of adding both pozzolans at all replacement levels. The water absorption increased as the capillary porosity increased; this effect depended on the volume of air entrained and the type or amount of pozzolan.

  3. Investigation of the use of fly-ash based autoclaved cellular concrete blocks in coal mines for air duct work. Final report, January 25, 1993--December 31, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Horvath, M.L. [Ohio Edison Co., Akron, OH (United States)

    1995-06-19

    Coal mines are required to provide ventilation to occupied portions of underground mines. Concrete block is used in this process to construct air duct walls. However, normal concrete block is heavy and not easy to work with and eventually fails dramatically after being loaded due to mine ceiling convergence and/or floor heave. Autoclaved cellular concrete block made from (70{plus_minus}%) coal fly ash is lightweight and less rigid when loaded. It is lighter and easier to use than regular concrete block for underground mine applications. It has also been used in surface construction around the world for over 40 years. Ohio Edison along with eight other electric utility companies, the Electric Power Research Institute (EPRI), and North American Cellular Concrete constructed a mobile demonstration plant to produce autoclaved cellular concrete block from utility fly ash. To apply this research in Ohio, Ohio Edison also worked with the Ohio Coal Development Office and CONSOL Inc. to produce autoclaved cellular concrete block not only from coal ash but also from LIMB ash, SNRB ash, and PFBC ash from various clean coal technology projects sponsored by the Ohio Coal Development Office. The purpose of this project was to demonstrate the potential for beneficial use of fly ash and clean coal technology by-products in the production of lightweight block.

  4. Concrete construction and properties of the difference equation derived from the cellular automaton using the filtration technique

    Science.gov (United States)

    Watanabe, Tomonori

    2002-01-01

    Following the proposal of a filtration technique by Nobe, Satsuma and Tokihiro, we concretely construct partial difference equations, which preserve any time evolution patterns of cellular automaton (CA) stably by the filtration technique. We illustrate how to develop a method of filtration for applying to the typical two spatial dimensional CA rule - the game of life - and verify that the filtration method provides the stable difference equation associated with the CA, compared with the inverse ultradiscretization. Besides, in order to discuss whether the filtration technique can lead one to partial differential equations from CA rules, we show a derivation of the Burgers equation from Rule 184 CA via the discrete Burgers equation constructed by the filtration method as an example.

  5. EXTERIOR PRESSURE OF THE GASEOUS MEDIUM AS AN ADDITIONAL TECHNOLOGICAL FACTOR FOR OPTIMIZING THE VAPORIZATION PROCESS IN THE PRODUCTION OF CELLULAR SILICATE CONCRETE

    Directory of Open Access Journals (Sweden)

    A. A. Rezanov

    2012-11-01

    Full Text Available Statement of the problem. The quality of silicate porous concrete is largely determined by vapor-ization processes at the stage of the formation of the macrostructure of the obtained material. In the production of cellular concrete with the use of injection molding, the existing manufacturing technologies do not enable the expeditious handling of the vaporization process. This is why there is a growing need to develop additional efficient methods of handling the vaporization process thus improving cellular silicate concrete.Results. Based on modelling and detailed examination of the balance of pressure affecting devel-oping gas pores, mechanisms and factors governing a defect-free structure are found. An additional governing factor, which is a pressure of the external gaseous medium, was discovered. The approaches to handling the vaporization process have been developed and a plant fitted with a system of automatic control of vaporization process by conscious operative pressuring effect from the external gaseous phase on a poring mixture has been designed.Conclusions. Theoretical validation along with the results of the experimental study help to arrive at the conclusion about the efficiency of the suggested system in controlling vaporization that could provide a good addition to the traditional injection molding and make it more susceptible against varying characteristics of raw materials.

  6. Research on the Factors of Class A Lightweight Cellular Concrete%A级轻质蜂窝水泥混凝土影响因素探索

    Institute of Scientific and Technical Information of China (English)

    陈建波; 马红宵; 穆琰; 任晓林; 张志国; 赵风清

    2014-01-01

    A kind of soap powder,interface agent N as the main component of the composite foaming agent was de-veloped.Factors affecting the light honeycomb cement concrete were researched.They are the foam,water feed ratio, cement,fly ash,and the impact of the amount of fiber pilot.The ratio has been optimized.By adj usting the ratio of ce-mentitious materials different density levels of cellular concrete blocks were got.By industrial test and optimize the production process parameters,class A Lightweight cellular concrete optimization ratio was got.The product has been tested to achieve JC 1062-2007"foam concrete block"FCB A0.5 B03 product rating,fire rating to A-level.%开发出一种以皂粉、界面剂 N等为主要组分的复合发泡剂,在其基础上开展轻质蜂窝水泥混凝土影响因素试验,对泡沫、水料比、水泥、粉煤灰、纤维的用量及影响进行试验研究,得到优化的配比,通过调整胶凝材料的配比可以得到不同密度等级的蜂窝混凝土砌块。通过工业化试验,优化生产工艺参数,得到 A 级轻质蜂窝水泥混凝土优化配比。产品经检测达到JC 1062-2007《泡沫混凝土砌块》FCB A0.5 B03产品等级,防火等级达到 A级。

  7. Thermal conductivity of a cellular clay concrete: case of a weight reduction by reaction with powdered aluminium

    Energy Technology Data Exchange (ETDEWEB)

    Marmoret, L.; Bouguerra, A.; Al Rim, K. [Rennes-1 Univ., 35 (France); Queneudec, M. [IUT, 35 - Rennes (France)

    1995-06-01

    The clay waste resulting from the exploitation of a large number of aggregate quarries are not really used at the present time. New technologies have been developed to recycle this waste by making insulating materials. The clay-cement mixture is lightened by powdered aluminium reacting with lime produced during the cement hydration, giving hydrogen bubbles. A good distribution of bubbles is dependent on components, atmosphere and rheologic properties of the wet mixture. So, in the first part, the authors present the influence of the different components on the thermal conductivity. They demonstrate the potential for reaching some good thermal performances with sufficient mechanical characteristics. At that point, the validation of experimental results can be seen in comparison with mathematic models already verified for autoclaved aerated concrete. (authors). 20 refs., 9 figs.

  8. Concrete Thinking

    OpenAIRE

    Kuang-Ming Wu

    2015-01-01

    Existence is concrete discerned bodily, thinking considers existents, and so concrete thinking is primal, at the base of logical thinking. Still, concrete actuality is reasonable beyond logical analysis. So, concrete thinking is “illogical” bodily reasonable. Thus this essay explores 1) concrete thinking various and 2) concrete thinking concretely. All this concrete thinking culminates in kids’ joys alive.

  9. Sub-cellular partitioning of metals (Cd, Cu, Zn) in the gills of a freshwater bivalve, Pyganodon grandis: role of calcium concretions in metal sequestration

    International Nuclear Information System (INIS)

    Indigenous unionid molluscs, Pyganodon grandis, were collected from nine lakes in the Rouyn-Noranda area (Quebec, Canada) along a polymetallic concentration gradient (Cd, Cu, Zn). After excision, the gills were gently homogenised and the cellular compartments were separated by a differential centrifugation procedure that yielded the following particulate fractions: 'nuclei + cellular debris', 'mitochondria', 'lysosomes + microsomes' and 'granules'. The supernatant remaining after the final ultracentrifugation step, i.e., the operationally-defined cytosol, was separated into a 'heat-denaturable proteins' (HDP) fraction and a 'heat-stable proteins' (HSP) fraction containing metallothionein (MT). The Cd, Cu and Zn content of each particulate and cytosolic fraction was determined and gill metallothionein was quantified independently by a mercury saturation assay. Cytosolic Cd concentrations were significantly related to the dissolved Cd concentrations at each site, but cytosolic Cu and Zn (essential metals) were not related to their respective ambient dissolved metal concentrations. Metallothionein concentrations increased along the metal contamination gradient and were related to cytosolic Cd (and Zn) in a concentration-dependent manner. However mass balance calculations showed that binding to metallothionein could only account for a small proportion of total gill metal (∼10% Cd; ∼3% Cu; ∼1% Zn). Under these chronic exposure conditions, the three metals (Cd, Cu and Zn) were mainly located in calcium concretions present in the gills (respectively 58 ± 13% of the total gill Cd, 64 ± 6% of the total gill Cu and 73 ± 6% of the total gill Zn). The overall contribution of granules to the total gill dry weight remained relatively constant among the different lakes, suggesting that lake-to-lake variations in granule synthesis were independent of the metal contamination gradient, i.e., these constituent elements of unionid gills act as non-inducible metal sinks at the

  10. How Concrete Is Concrete?

    Science.gov (United States)

    Gravemeijer, Koeno

    2011-01-01

    If we want to make something concrete in mathematics education, we are inclined introduce, what we call, "manipulatives", in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own,…

  11. SHRINKAGE STRAIN AT THE FORMATION OF THE STRUCTURE OF CELLULAR CONCRETE / УСАДОЧНЫЕ ДЕФОРМАЦИИ ПРИ ФОРМИРОВАНИИ СТРУКТУРЫ ЯЧЕИСТОГО БЕТОНА

    OpenAIRE

    Zhukov A. D. / Жуков Алексей Дмитриевич; Naumova N. V. / Наумова Наталья Владимировна; Chkunin A. S. / Чкунин Анатолий Сергеевич

    2014-01-01

    Structure formation of cellular concrete in a limited volume leads to the creation of the pressure gradient and the concentration and redistribution of moisture in the mineral matrix and also to increase its density. With well-chosen mixture compositions and modes of formation it can lead to low-shrinkage of autoclaved aerated concrete. The authors study shrinkage of traditional cellular concrete and optimal compositions and its changes over time. It is shown that the greatest shrinkage occur...

  12. How Concrete is Concrete

    Directory of Open Access Journals (Sweden)

    Koeno Gravemeijer

    2010-07-01

    Full Text Available If we want to make something concrete in mathematics education, we are inclined introduce, what we call, ‘manipulatives’, in the form of tactile objects or visual representations. If we want to make something concrete in a everyday-life conversation, we look for an example. In the former, we try to make a concrete model of our own, abstract, knowledge; in the latter, we try to find an example that the others will be familiar with. This article first looks at the tension between these two different ways of making things concrete. Next another role of manipulatives, will be discussed, namely that of means for scaffolding and communication. In this role, manipulatives may function as means of support in a process that aims at helping students to build on their own thinking while constructing more sophisticated mathematics

  13. Concrete Hinges

    DEFF Research Database (Denmark)

    Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

    2014-01-01

    In the first part of the 20th century concrete hinges developed by Freyssinet and Mesnager were widely tested and implemented in concrete structures. The concrete hinges were used a great deal in closed-spandrel arch bridges. Since such a bridge type has not been competitive for the past 40 years......, the research in concrete hinges has not evolved significantly in that period. But introducing a new state-of-the-art concrete arch bridge solution (Pearl-Chain arches invented at the Technical University of Denmark) creates a necessity of a concrete hinge research based on modern standards. Back when...

  14. Pervious Concrete

    OpenAIRE

    Torsvik, Øyvind André Hoff

    2011-01-01

    Pervious concrete is a type of concrete with little or no fines which give a large void. This enables high permeability and because of this it enables water to percolate through the concrete. Pervious concrete have been used in many years both as pavement material and on several other applications in the U.S and in other countries in Western Europe. In Norway pervious concrete is not currently in use. This thesis aims to investigate if pervious concrete can withstand the harsh Norwegian clima...

  15. Structural Precast Concrete Handbook

    DEFF Research Database (Denmark)

    Kjærbye, Per Oluf H

    Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly.......Structural concept for precast concrete systems. Design og precast reinforced concrete components. Design of precast concrete connections. Illustrations on design of precast concrete buildings. Precast concrete assembly....

  16. Glazed Concrete

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    Why glazed concrete? Concrete hardens and finds its strength at room temperature whereas clay products must first be fired before they achieve this strength. They are stronger and three times as durable as clay products, which is a weighty reason for choosing concrete.5 Another reason, which is the...... succeeds, it will be possible to manufacture thin, large-scale glazed concrete panels comparable in size to concrete sandwich construction and larger which, with or without back-casting, can work as load-bearing construction elements....

  17. NANOMODIFIED CONCRETE

    Directory of Open Access Journals (Sweden)

    B. M. Khroustalev

    2015-12-01

    Full Text Available One of the main directions in construction material science is the development of  next generation concrete that is ultra-dense, high-strength, ultra-porous, high heat efficient, extra corrosion-resistant. Selection of such direction is caused by extreme operational impacts on the concrete, namely: continuously increasing load on the concrete and various dynamics of such loads; the necessity in operation of concrete products in a wide temperature range and their exposure to various chemical and physical effects.The next generation concrete represents high-tech concrete mixtures with additives that takes on and retain the required properties when hardening and being used under any operational conditions. A differential characteristic of the next generation concrete is its complexity that presumes usage of various mineral dispersed components, two- and three fractional fine and coarse aggregates, complex chemical additives, combinations of polymer and iron reinforcement.Design strength and performance properties level of the next generation concrete is achieved by high-quality selection of the composition, proper selection of manufacturing techniques, concrete curing, bringing the quality of concrete items to the required level of technical condition during the operational phase. However, directed formation of its structure is necessary in order to obtain high-tech concrete.Along with the traditional methods for regulation of the next generation concrete structure, modification of concrete while using silica nanoparticles is also considered as a perspective one because the concrete patterning occurs due to introduction of a binder in a mineral matrix. Due to this it is possible to obtain nano-modified materials with completely new properties.The main problem with the creation of nano-modified concrete is a uniform distribution of nano-materials in the volume of the cement matrix which is particularly important in the cases of adding a modifier in

  18. Concrete products

    Energy Technology Data Exchange (ETDEWEB)

    Anon

    2002-01-01

    Increased strength and durability in concrete products can be achieved through the addition of fly ash during the manufacturing process. The properties of concrete are enhanced by fly ash. The benefits include cost and the environment. Fly ash is normally defined as finely divided residue resulting from the combustion of pulverized coal, carried from the combustion chamber to the furnace by exhaust gas. The main applications of fly ash in concrete products are ready mix concrete, bridge decks and support footing, precast structures, blocks and bricks, and pipes. The Canadian Standards Association (CSA) has published standards to ensure that the desired physical properties of the concrete are achieved and the standards are found in CSA A23.1, detailing the engineering materials and mix proportions. The type of fly ash to be used for specific properties is important. Finishing and curing operations must be performed with care. The free lime generated by cement hydration reacts with fly ash, forming additional calcium silicate hydrate. Permeability of the concrete is reduced since the calcium silicate hydrate fills the void resulting from the cement pour. Some of the benefits to be derived from fly ash in concrete are: water reduction, improved workability, high ultimate strength, improved pumpability, and reduced heat of hydration. In addition, the life cycle costs are lower, and great strength is obtained. An environmental benefit results from the reduction of natural resource consumption.

  19. Photocatalyticpaving concrete

    Directory of Open Access Journals (Sweden)

    Lyapidevskaya Ol'ga Borisovna

    2014-02-01

    Full Text Available Today bituminous concrete is a conventional paving material. Among its advantages one can name dustlessness and noiselessness, fine wear (up to 1 mm a year and fine maintainability. As the main disadvantages of this material one can name high slipperiness under humidification, low durability and weather resistance. Besides that, during placement of the bituminous concrete a lot of different air pollutants are emitted, which are harmful for environment and human’s health (they are listed in the paper according to the US Environmental Protection Agency materials. As an alternative, one can use cement-concrete pavement, which is in many ways more efficient than the bituminous concrete. It is proposed to enhance environmental performance of the cement-concrete pavement via usage of photocatalysis. The mechanism of different photocatalytic reactions is described in the paper, namely heterogeneous and homogeneous photocatalysis, photo-induces, photoactivated catalysis and catalytical photoreactions. It is pro-posed to use heterogeneous photocatalysis with titanium dioxide as a photocatalyst. The mechanism of photo oxidation of air contaminants, with the usage of titanium dioxide is2described. The paper sets problems, connected with the sensibilization of TiOto thevisible light (it is proposed to use titanium dioxide, doped with the atoms of certain elements to increase its sensibility to the visible light and with the development of a new photocatalytic paving concrete, which will meet the requirements, specified for paving in the climatic and traffic conditions of the Russian Federation.

  20. Self-Placing Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Certain concrete pours have areas where the congestion of reinforcing bars make placement of concrete almost impossible. Using conventional placing and vibration techniques, the resulting concrete can have considerable honeycombing due to the development of voids. Self-placing concrete is a possible solution to the problem. Also known as self-compactable concrete, self-consolidating concrete, flowable concrete, and non-vibration concrete. These concretes eliminate the need for vibration in a ...

  1. High Performance Concrete (HPC)

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Normal Strength Concrete (NSC) is heavy and lacks the required workability in some large concrete structures, such as high-rise buildings, bridges, and structures under severe exposure conditions. High Performance Concrete (HPC) is the latest development in concrete.

  2. Historic Concrete: From Concrete Repair to Concrete Conservation

    NARCIS (Netherlands)

    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

  3. A Matrix Construction of Cellular Algebras

    Institute of Scientific and Technical Information of China (English)

    Dajing Xiang

    2005-01-01

    In this paper, we give a concrete method to construct cellular algebras from matrix algebras by specifying certain fixed matrices for the data of inflations. In particular,orthogonal matrices can be chosen for such data.

  4. High Performance Concrete

    OpenAIRE

    Traian Oneţ

    2009-01-01

    The paper presents the last studies and researches accomplished in Cluj-Napoca related to high performance concrete, high strength concrete and self compacting concrete. The purpose of this paper is to raid upon the advantages and inconveniences when a particular concrete type is used. Two concrete recipes are presented, namely for the concrete used in rigid pavement for roads and another one for self-compacting concrete.

  5. Concrete construction engineering handbook

    CERN Document Server

    Nawy, Edward G

    2008-01-01

    Provides coverage of concrete construction engineering and technology. This work features discussions focusing on: the advances in engineered concrete materials; reinforced concrete construction; specialized construction techniques; and, design recommendations for high performance.

  6. Concrete and reinforced concrete - glance at future

    OpenAIRE

    Tamrazyan Ashot Georgievich

    2014-01-01

    In the article the information on the upcoming international conference on concrete and reinforced concrete is offered. The aim of the conference is stated, as well as the main points of the program, composition of the conference, the papers’ subject is disclosed. The author highlights the effect of reinforced concrete invention on the world civilization development. According to the author’s point of view, today reinforced concrete became one of the most evident means of the world developmen...

  7. The Future Concrete: Self-Compacting Concrete

    OpenAIRE

    Liana Iureş; Corneliu Bob

    2010-01-01

    The paper presents the characteristics of the self-compacting concretes, their advantages and disadvantages when they are used in buildings. Due to its properties and composition, the self-compacting concrete is described here as being one of the future friendly enviromental material for buildings. Tests concerning to obtaining a self-compacting concrete, together with the specific fresh concrete properties tests, are described.

  8. Concrete durability

    Directory of Open Access Journals (Sweden)

    Gaspar Tébar, Demetrio

    1991-03-01

    Full Text Available The evidence that the concrete is not a material for ever was noticed from the beginning of its industrial use. In the present work, the author describes the studies carried out during the last century and the early ages of the present one, mainly devoted to the study of the durability in sea water. At the present days, and in spite of the numerous papers published from then, the study of the concrete durability continues focusing the research priorities and economical resources of researchers and industries related with this material. Moreover, the new laboratory techniques are allowing to understand old problems and even to open again the discussion on reaction mechanisms which were believed to be completely understood. The article finalizes with a brief description of the numerous studies carried out at the Institute Eduardo Torroja on concrete durability, mainly those related with the resistance against gypsum attack (so abundant in our country land and against sea water attack.

    La realidad de que el hormigón no es un material eterno y es susceptible de sufrir ataques por agentes químicos, fue constatada desde el comienzo mismo de su uso industrial. En el presente trabajo el autor enumera los estudios realizados el siglo pasado y a comienzos del presente sobre la durabilidad del hormigón en agua de mar. En la actualidad y a pesar de los numerosos trabajos desarrollados desde entonces, el estudio de la durabilidad del hormigón sigue centrando la atención prioritaria y los recursos económicos de los investigadores e industrias relacionadas con este material. Además las nuevas técnicas de estudio están permitiendo comprender antiguos problemas e incluso reabrir la discusión sobre mecanismos de reacción que se creían completamente explicados. Finaliza el artículo con una descripción somera de los múltiples trabajos realizados en el Instituto Eduardo Torreja sobre la materia, en especial los estudios realizados sobre

  9. Rapid Drying Concrete

    OpenAIRE

    ECT Team, Purdue

    2015-01-01

    One of the essential problems that are faced during construction is the drying of concrete and the presence of moisture which affects floor coverings that need to be placed. The rapid-drying characteristic in Aridusâ concrete allows for the quick reduction of moisture vapor that travels through the concrete pores of the concrete.

  10. Self-Compacting Concrete

    OpenAIRE

    Okamura, Hajime; OUCHI, Masahiro

    2003-01-01

    Self-compacting concrete was first developed in 1988 to achieve durable concrete structures. Since then, various investigations have been carried out and this type of concrete has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mix-design method and self-compactability testing methods have been carried out from the viewpoint of making self-compacting concrete a standard concrete.

  11. Mobile concrete factory profiability analysis

    OpenAIRE

    Bajželj, Grega

    2009-01-01

    Diploma task deals with the preparation of concrete in the mobile and stationary concrete factory, transport of concrete and the comparison between the cost of preparation of concrete in the mobile and stationary concrete factory. Represented is the way of preparation of concrete in the mobile and stationary concrete factory. I conducted an analysis of the viability of mobile concrete factory, based on a comparison of the cost of preparation of concrete in the mobile and the cost of preparing...

  12. Cellular automata

    CERN Document Server

    Codd, E F

    1968-01-01

    Cellular Automata presents the fundamental principles of homogeneous cellular systems. This book discusses the possibility of biochemical computers with self-reproducing capability.Organized into eight chapters, this book begins with an overview of some theorems dealing with conditions under which universal computation and construction can be exhibited in cellular spaces. This text then presents a design for a machine embedded in a cellular space or a machine that can compute all computable functions and construct a replica of itself in any accessible and sufficiently large region of t

  13. Moisture conditions of modern structures made of autoclaved aerated concrete in operation period

    Directory of Open Access Journals (Sweden)

    P.S. Zyryanov

    2011-03-01

    Full Text Available In St.-Petersburg and area six organizations making cellular concrete of autoclave hardening operate. At all enterprises the cellular concrete is made by the gas way of pore development by molding technology. The molding technology in practice means that the mass humidity of concrete on an exit from autoclaves will be at level of 35-45 % (great values of humidity correspond to smaller density. The similar situation is observed in other regions: more than 80 % of all autoclave cellular concrete in Russia are made by molding technology. The high humidity caused by presence of technological and constructional moisture in an initial stage of operation quickly decreases, reaching gradually operational level. The established humidity of cellular autoclave concrete as a part of protecting walls makes 3–6 % on weight. However the raised humidity of cellular concrete in an operation initial stage causes smaller settlement values of durability of concrete in a laying. Durability of concrete, in turn, influences on bearing capacity of anchorings for ventilated facades, if they are fastened in a body of cellular concrete. Thus, the information on dynamics of change of laying humidity in an operation initial stage allows to estimate terms of reach by designs calculated strength and thermophysical parameters.

  14. Sustainable Concrete Technology

    Directory of Open Access Journals (Sweden)

    Sim J.

    2015-12-01

    Full Text Available The growing concern over global warming and significant ecological changes requires sustainable development in all fields of science and technology. Concrete not only consumes huge amount of energy and natural sources, but also emits large amount of CO2, mainly due to the production of cement. It is evident that such large amount of concrete production has put significant impact on the energy, resource, environment, and ecology of the society. Hence, how to develop the concrete technology in a sustainable way has become a significant issue. In this paper, some of Korean researches for sustainable development of concrete are presented. These are sustainable strengthening for deteriorated concrete structure, sustainable reinforcement of new concrete structure, sustainable concrete using recycled aggregate and supplementary cementing materials and finally application of each technique to precast concrete.

  15. Designing concrete for durability

    OpenAIRE

    Boyd, A.J.; Mindess, S.; Skalny, J.

    2001-01-01

    Some of the factors affecting the durability of modern concrete structures are discussed, with an emphasis on the problems caused by modern portland cements. This is followed by a description of some concrete durability issues of current interest, such as plastic shrinkage, seawater attack, and sulfate attack. The strategies for testing for durability are also discussed. It is concluded that, to produce durable concretes, a holistic approach to concrete construction must be adopted.
    ...

  16. Deterioration of Concrete Structures

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Chloride ingress is a common cause of deterioration of reinforced concrete bridges. Concrete may be exposed to chloride by seawater or de-icing salts. The chloride initiates corrosion of the reinforcement, which through expansion disrupts the concrete. In addition, the corrosion reduces the cross...

  17. concrete5 for developers

    CERN Document Server

    Uzayr, Sufyan bin

    2014-01-01

    Whether you have had some previous experience with concrete5 or are entirely new to it, this book will help you understand all that you need to know in order to get started with concrete5 development. A background in PHP is required; some knowledge of HTML/CSS is needed in order to fully grasp the concepts underlying concrete5 theme development.

  18. Quantum cellular automata

    Science.gov (United States)

    Porod, Wolfgang; Lent, Craig S.; Bernstein, Gary H.

    1994-06-01

    The Notre Dame group has developed a new paradigm for ultra-dense and ultra-fast information processing in nanoelectronic systems. These Quantum Cellular Automata (QCA's) are the first concrete proposal for a technology based on arrays of coupled quantum dots. The basic building block of these cellular arrays is the Notre Dame Logic Cell, as it has been called in the literature. The phenomenon of Coulomb exclusion, which is a synergistic interplay of quantum confinement and Coulomb interaction, leads to a bistable behavior of each cell which makes possible their use in large-scale cellular arrays. The physical interaction between neighboring cells has been exploited to implement logic functions. New functionality may be achieved in this fashion, and the Notre Dame group invented a versatile majority logic gate. In a series of papers, the feasibility of QCA wires, wire crossing, inverters, and Boolean logic gates was demonstrated. A major finding is that all logic functions may be integrated in a hierarchial fashion which allows the design of complicated QCA structures. The most complicated system which was simulated to date is a one-bit full adder consisting of some 200 cells. In addition to exploring these new concepts, efforts are under way to physically realize such structures both in semiconductor and metal systems. Extensive modeling work of semiconductor quantum dot structures has helped identify optimum design parameters for QCA experimental implementations.

  19. Autogenous Deformation of Concrete

    DEFF Research Database (Denmark)

    Autogenous deformation of concrete can be defined as the free deformation of sealed concrete at a constant temperature. A number of observed problems with early age cracking of high-performance concretes can be attributed to this phenomenon. During the last 10 years , this has led to an increased...... focus on autogenous deformation both within concrete practice and concrete research. Since 1996 the interest has been significant enough to hold international, yearly conferences entirely devoted to this subject. The papers in this publication were presented at two consecutive half-day sessions at the...... American Concrete Institute’s Fall Convention in Phoenix, Arizona, October 29, 2002. All papers have been reviewed according to ACI rules. This publication, as well as the sessions, was sponsored by ACI committee 236, Material Science of Concrete. The 12 presentations from 8 different countries indicate...

  20. Recycled Concrete as Aggregate for Structural Concrete Production

    OpenAIRE

    Mirjana Malešev; Vlastimir Radonjanin; Snežana Marinković

    2010-01-01

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

  1. Special protective concretes

    International Nuclear Information System (INIS)

    Concrete is the most convenient material when large-scale radiation protection is needed. Thus, special concretes for nuclear purposes are used in various facilities like reactors, reprocessing centers, storage sites, accelerators, hospitals with nuclear medicine equipment, food ionization centers etc.. The recent advances made in civil engineering for the improvement of concrete durability and compactness are for a large part transposable to protection concretes. This article presents the basic knowledge about protection concretes with the associated typological and technological aspects. A large part is devoted to the intrinsic properties of concretes and to their behaviour in irradiation and temperature conditions: 1 - definition and field of application of special protective concretes; 2 - evolution of concepts and technologies (durability of structures, techniques of formulation, new additives, market evolution); 3 - design of protective structures (preliminary study, radiation characteristics, thermal constraints, damping and dimensioning, mechanical criteria); 4 - formulation of special concretes (general principles, granulates, hydraulic binders, pulverulent additives, water/cement ratio, reference composition of some special concretes); 5 - properties of special concretes (damping and thermo-mechanical properties); 6 - induced-irradiation and temperature phenomena (activation, radiolysis, mineralogical transformations, drying, shrinking, creep, corrosion of reinforcement). (J.S.)

  2. Cellular Automata

    OpenAIRE

    Bagnoli, Franco

    1998-01-01

    An introduction to cellular automata (both deterministic and probabilistic) with examples. Definition of deterministic automata, dynamical properties, damage spreading and Lyapunov exponents; probabilistic automata and Markov processes, nonequilibrium phase transitions, directed percolation, diffusion; simulation techniques, mean field. Investigation themes: life, epidemics, forest fires, percolation, modeling of ecosystems and speciation. They represent my notes for the school "Dynamical Mod...

  3. Modeling of fracture of protective concrete structures under impact loads

    Science.gov (United States)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-10-01

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  4. Modeling of fracture of protective concrete structures under impact loads

    International Nuclear Information System (INIS)

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces

  5. Modeling of fracture of protective concrete structures under impact loads

    Energy Technology Data Exchange (ETDEWEB)

    Radchenko, P. A., E-mail: radchenko@live.ru; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S. [Tomsk State University of Architecture and Building, Tomsk, 634003 (Russian Federation)

    2015-10-27

    This paper presents results of numerical simulation of interaction between a Boeing 747-400 aircraft and the protective shell of a nuclear power plant. The shell is presented as a complex multilayered cellular structure consisting of layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was performed three-dimensionally using the original algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. Dynamics of the stress-strain state and fracture of the structure were studied. Destruction is described using a two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of the cellular shell structure; cells start to destruct in an unloading wave originating after the compression wave arrival at free cell surfaces.

  6. Nanostructured silicate polymer concrete

    Directory of Open Access Journals (Sweden)

    Figovskiy Oleg L'vovich

    2014-03-01

    Full Text Available It has been known that acid-resistant concretes on the liquid glass basis have high porosity (up to 18~20 %, low strength and insufficient water resistance. Significant increasing of silicate matrix strength and density was carried out by incorporation of special liquid organic alkali-soluble silicate additives, which block superficial pores and reduce concrete shrinkage deformation. It was demonstrated that introduction of tetrafurfuryloxisilane additive sharply increases strength, durability and shock resistance of silicate polymer concrete in aggressive media. The experiments showed, that the strength and density of silicate polymer concrete increase in case of decreasing liquid glass content. The authors obtained optimal content of silicate polymer concrete, which possesses increased strength, durability, density and crack-resistance. Diffusive permeability of concrete and its chemical resistance has been investigated in various corroding media.

  7. Low Temperature Concrete Admixture

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Performing construction processes under the cold weather condition requires construction engineers to plan operations considering low temperature condition. Concrete admixture mostly chemically interact with the constituents of concrete and affect the properties and characteristics of the fresh and hardened concrete and its durability. The purposes of the admixtures include water reduction, high strength, corrosion protection, crack control, finish enhancement, flowability, etc. One of the in...

  8. Concrete bridge prioritization system

    OpenAIRE

    Kesselring, Debbie Anne

    1995-01-01

    An alternative method of prioritization for concrete bridge maintenance, repair, and rehabilitation activities is required due to the inability of the current system to manage the increasing nmnber of aging concrete bridges. The Concrete Bridge Prioritization System was proposed because of its ability to address the critical technical parameters of safety and cost benefit in prioritization of funding and work allocation. The analysis includes four parts, service life assessment, s...

  9. Sustainable Concrete Technology

    OpenAIRE

    Sim J.; Lee K.H.

    2015-01-01

    The growing concern over global warming and significant ecological changes requires sustainable development in all fields of science and technology. Concrete not only consumes huge amount of energy and natural sources, but also emits large amount of CO2, mainly due to the production of cement. It is evident that such large amount of concrete production has put significant impact on the energy, resource, environment, and ecology of the society. Hence, how to develop the concrete technology in ...

  10. Numerical simulation of deformation and fracture of space protective shell structures from concrete and fiber concrete under pulse loading

    Science.gov (United States)

    Radchenko, P. A.; Batuev, S. P.; Radchenko, A. V.; Plevkov, V. S.

    2015-11-01

    This paper presents results of numerical simulation of interaction between aircraft Boeing 747-400 and protective shell of nuclear power plant. The shell is presented as complex multilayered cellular structure comprising layers of concrete and fiber concrete bonded with steel trusses. Numerical simulation was held three-dimensionally using the author's algorithm and software taking into account algorithms for building grids of complex geometric objects and parallel computations. The dynamics of stress-strain state and fracture of structure were studied. Destruction is described using two-stage model that allows taking into account anisotropy of elastic and strength properties of concrete and fiber concrete. It is shown that wave processes initiate destruction of shell cellular structure—cells start to destruct in unloading wave, originating after output of compression wave to the free surfaces of cells.

  11. Computational models for the nonlinear analysis of reinforced concrete plates

    Science.gov (United States)

    Hinton, E.; Rahman, H. H. A.; Huq, M. M.

    1980-01-01

    A finite element computational model for the nonlinear analysis of reinforced concrete solid, stiffened and cellular plates is briefly outlined. Typically, Mindlin elements are used to model the plates whereas eccentric Timoshenko elements are adopted to represent the beams. The layering technique, common in the analysis of reinforced concrete flexural systems, is incorporated in the model. The proposed model provides an inexpensive and reasonably accurate approach which can be extended for use with voided plates.

  12. Concrete portable handbook

    CERN Document Server

    Woodson, R Dodge

    2011-01-01

    Whether or not, you are on the job site or back in the office, this book will help you to avoid mistakes, code violations, and wasted time and money. The book's four part treatment begins with constituent materials followed by self contained parts on Concrete Properties, Processes, and Concrete Repair and Rehabilitation. Designed to be an ""all in one"" reference, the author includes a wealth information for the most popular types of testing. This includes: Analysis of Fresh Concrete; Testing Machines; Accelerated Testing Methods; Analysis of Hardened Concrete and Mortar; Core Sampl

  13. SHRINKAGE STRAIN AT THE FORMATION OF THE STRUCTURE OF CELLULAR CONCRETE / УСАДОЧНЫЕ ДЕФОРМАЦИИ ПРИ ФОРМИРОВАНИИ СТРУКТУРЫ ЯЧЕИСТОГО БЕТОНА

    Directory of Open Access Journals (Sweden)

    Zhukov A. D. / Жуков Алексей Дмитриевич

    2014-12-01

    Full Text Available Structure formation of cellular concrete in a limited volume leads to the creation of the pressure gradient and the concentration and redistribution of moisture in the mineral matrix and also to increase its density. With well-chosen mixture compositions and modes of formation it can lead to low-shrinkage of autoclaved aerated concrete. The authors study shrinkage of traditional cellular concrete and optimal compositions and its changes over time. It is shown that the greatest shrinkage occur in the early stages of structure formation and hardening of aerated concrete. The optimization is implemented and the technique of selection of non-autoclaved aerated concrete is developed / Структурообразование ячеистого бетона в условиях ограниченного объема приводит к созданию градиентов давлений и концентраций и перераспределению влаги в минеральной матрице, а также к повышению ее плотности, что значительно снижает усадку. Осуществлена оптимизация и разработана методика подбора состава неавтоклавного ячеистого бетона

  14. Concrete fracture models and applications

    CERN Document Server

    Kumar, Shailendra

    2011-01-01

    Concrete-Fracture Models and Applications provides a basic introduction to nonlinear concrete fracture models. Readers will find a state-of-the-art review on various aspects of the material behavior and development of different concrete fracture models.

  15. Environmental Impact of Concrete

    Directory of Open Access Journals (Sweden)

    Dan Babor

    2009-01-01

    Full Text Available The cement and concrete industries are huge. What does this mean in terms of the environment? Concrete and other cementitious materials have both environmental advantages and disadvantages. This paper takes a look at how these materials are made, then reviews a number of environmental considerations relating to their production and use.

  16. Concrete, hardened: Self desiccation

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard; Persson, Bertil

    1999-01-01

    The test method covers the determination of internal relative humidity (RH) in hardened concrete and cement mortar using RH instruments. The determination of RH is done on crushed samples of concrete or cement motar. This test method is only for measuring equipment which gives off or takes up...

  17. Service life of concrete

    International Nuclear Information System (INIS)

    The US Nuclear Regulatory Commission (NRC) has the responsibility for developing a strategy for the disposal of low-level radioactive waste (LLW). An approach being considered for their disposal is to place the waste forms in concrete vaults buried in the earth. A service life of 500 years is required for the concrete vaults as they may be left unattended for much of their lives. This report examines the basis for making service life predictions based on accelerated testing and mathematical modeling of factors controlling the durability of concrete buried in the ground. Degradation processes are analyzed based on considerations of their occurrence, extent of potential damage, and mechanisms. A recommended research plan for developing methods for predicting the service life of concrete is presented. The major degradation processes that concrete of underground vaults will likely encounter are sulfate attack, corrosion of reinforcing steel, alkali-aggregate reactions, and leaching by ground water. Freezing and thawing damage could occur before the vaults are covered with soil and therefore are addressed. Other degradation processes which may occur are microbiological attack, salt crystallization, and attack by LLW, especially by acidic materials. Two important factors controlling the resistance of concrete to these degradation processes are its quality and permeability. Concepts of quality and factors affecting quality of concrete are discussed. Permeability is discussed in terms of the water-to-cement ratio, the pore structure of concrete, and the effects of cracks. 101 refs., 15 figs., 5 tabs

  18. concrete5 Beginner's Guide

    CERN Document Server

    Laubacher, Remo

    2011-01-01

    This book is part of Packt's Beginner's Guide series. You will be guided through the set up of a Concrete5 site with step-by-step practical examples. This book is ideal for developers who would like to build their first site with Concrete5. Some k

  19. Environmental Impact of Concrete

    OpenAIRE

    Dan Babor; Diana Plian; Loredana Judele

    2009-01-01

    The cement and concrete industries are huge. What does this mean in terms of the environment? Concrete and other cementitious materials have both environmental advantages and disadvantages. This paper takes a look at how these materials are made, then reviews a number of environmental considerations relating to their production and use.

  20. Concrete-Design

    Directory of Open Access Journals (Sweden)

    Leczovics Péter

    2014-12-01

    Full Text Available Present paper introduces a new interpretation of concrete, demonstrating some extreme possibilities of this rigid material such as a design element. In the first part a brief overview of the previous achievements are shown. The second part of this paper focuses on the relationship between concrete and fashion.

  1. Sodium concrete reactions

    International Nuclear Information System (INIS)

    The data from an extensive series of sodium/concrete reaction tests are presented and mechanisms by which the reactions proceed are analyzed. The results indicate water transport and the resulting sodium/water reaction dominate both the chemical energy release and H2 generation. A mechanism which explains the limited penetration of concrete observed in most of these tests is proposed

  2. Concrete quality assurance

    Energy Technology Data Exchange (ETDEWEB)

    Holz, N. [Harza Engineering Company, Chicago, IL (United States)

    2000-08-01

    This short article reports on progress at the world's largest civil construction project, namely China's Three Gorges hydro project. Work goes on around the clock to put in place nearly 28 M m{sup 3} of concrete. At every stage of the work there is strong emphasis on quality assurance (QA) and concrete is no exception. The US company Harza Engineering has been providing QA since the mid-1980s and concrete QA has been based on international standards. Harza personnel work in the field with supervisors developing educational tools for supervising concrete construction and quality, as well as providing training courses in concrete technology. Some details on flood control, capacity, water quality and environmental aspects are given..

  3. Electrokinetic decontamination of concrete

    International Nuclear Information System (INIS)

    Concrete structures which have been contaminated with uranium and other radioisotopes may be decontaminated using in-situ electrokinetic remediation. By placing an electrode cell on the concrete surface and using the concrete's rebar, a ground rod, or another surface cell as the counter electrode, the radioisotopes may be migrated from the concrete into this cell. The process is highly dependent upon the chemical parameters of the species involved; namely, the concrete, the contaminants, and the solubilizers used to mobilize the contaminants. In a preliminary study conducted at the K-25 Site of the Oak Ridge National Labs, an estimated removal of >40 percent of uranium has been observed for a short duration run. This removal occurred using traditional uranium solubilizers in contact with the contaminated surface

  4. Expansion of Hanford concrete

    International Nuclear Information System (INIS)

    This report presents results of measurements of thermal expansion of concrete cores from Hanford, Washington facilities, and concrete cast at the Construction Technology Laboratories of Portland Cement Association (CTL/PCA). Thermal expansion was measured from room temperature to 16000F on 0.5 x 3.0-in. specimens heated at a rate of 100F/min. Specimens were cored from concrete cylinders cast at CTL/PCA in 1975 and 1977, and from cylindrical cores taken from the Purex Building and Waste Tank Farms at the Hanford, Washington complex. A total of 14 specimens were tested: eight tests on CTL/PCA cast concrete, two tests on material from the Purex Building, and four tests on Waste Tank Farms concrete. All tests were conducted using a commercially built dilatometer of high strain resolution

  5. Cellular resilience.

    Science.gov (United States)

    Smirnova, Lena; Harris, Georgina; Leist, Marcel; Hartung, Thomas

    2015-01-01

    Cellular resilience describes the ability of a cell to cope with environmental changes such as toxicant exposure. If cellular metabolism does not collapse directly after the hit or end in programmed cell death, the ensuing stress responses promote a new homeostasis under stress. The processes of reverting "back to normal" and reversal of apoptosis ("anastasis") have been studied little at the cellular level. Cell types show astonishingly similar vulnerability to most toxicants, except for those that require a very specific target, metabolism or mechanism present only in specific cell types. The majority of chemicals triggers "general cytotoxicity" in any cell at similar concentrations. We hypothesize that cells differ less in their vulnerability to a given toxicant than in their resilience (coping with the "hit"). In many cases, cells do not return to the naive state after a toxic insult. The phenomena of "pre-conditioning", "tolerance" and "hormesis" describe this for low-dose exposures to toxicants that render the cell more resistant to subsequent hits. The defense and resilience programs include epigenetic changes that leave a "memory/scar" - an alteration as a consequence of the stress the cell has experienced. These memories might have long-term consequences, both positive (resistance) and negative, that contribute to chronic and delayed manifestations of hazard and, ultimately, disease. This article calls for more systematic analyses of how cells cope with toxic perturbations in the long-term after stressor withdrawal. A technical prerequisite for these are stable (organotypic) cultures and a characterization of stress response molecular networks. PMID:26536287

  6. Using small cellular concrete blocks to make bearing walls of mid-rise buildings ПРИМЕНЕНИЕ СТЕНОВЫХ МЕЛКИХ БЛОКОВИЗ ЯЧЕИСТЫХ БЕТОНОВ В НЕСУЩИХ СТЕНАХ ЗДАНИЙ СРЕДНЕЙ ЭТАЖНОСТИ

    Directory of Open Access Journals (Sweden)

    Malakhova Anna Nikolaevna

    2013-01-01

    Full Text Available The authors argue that bearing walls of buildings that have up to four stories can be designed and made of small cellular concrete blocks. These walls demonstrate advantages specific to solid masonry walls. For example, they have high water vapor permeability. Whenever the internal humidity increases, half of the moisture content can be extracted from the masonry due to the water vapour permeability of external walls, while the other half of the moisture content can go back into the room (due to the sorption capacity of the wall material. Furthermore, any lower density wall material has smaller heat absorption capacity to ensure a comfortable environment.The application of small cellular concrete blocks as a wall material is an alternative to thoroughly insulated multi-layer external walls. The authors present options of structural solutions of external walls of buildings.It is noteworthy that due to the relatively low strength of cellular concrete, walls have a low bearing capacity. Cellular concretes are brittle.Control tests of small cellular concrete blocks made in the natural environment do not always prove the desired compressive strength. In addition, strength properties of small cellular concrete wall blocks may vary. The authors present their findings in terms of their examination of the technical condition of mid-rise buildings that have walls made of small cellular concrete blocks. The authors consider the reasons for the defects of walls made of small cellular concrete blocks.Рассмотрены варианты конструктивного решения наружных стен зданий средней этажности. Показаны достоинства стен сплошной каменной кладки. Приведены рекомендации по применению мелких стеновых блоков из ячеистых бетонов, а также результаты об

  7. Concrete sample point: 304 Concretion Facility

    International Nuclear Information System (INIS)

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis

  8. Concrete sample point: 304 Concretion Facility

    Energy Technology Data Exchange (ETDEWEB)

    Rollison, M.D.

    1995-03-10

    This report contains information concerning the analysis of concretes for volatile organic compounds. Included are the raw data for these analysis and the quality control data, the standards data, and all of the accompanying chains-of-custody records and requests for special analysis.

  9. Recycling of autoclaved aerated concrete in floor screeds: Sulfate leaching reduction by ettringite formation

    OpenAIRE

    Bergmans, Jef; Nielsen, Peter; Snellings, Ruben; Broos, Kris

    2016-01-01

    Autoclaved aerated concrete (AAC) is a lightweight cellular concrete. Recycling AAC in concrete or unbound applications may cause problems because of high amounts of leachable sulfate. This study evaluates the recycling of AAC demolition waste as a replacement of sand in floor screed. The cement binder reacted with sulfate released from the AAC waste to form ettringite. Sulfate release was in line with ettringite solubility control and below leaching limits defined by Dutch environmental legi...

  10. Performance of Waterless Concrete

    Science.gov (United States)

    Toutanji, Houssam; Evans, Steve; Grugel, Richard N.

    2010-01-01

    The development of permanent lunar bases is constrained by performance of construction materials and availability of in-situ resources. Concrete seems a suitable construction material for the lunar environment, but water, one of its major components, is an extremely scarce resource on the Moon. This study explores an alternative to hydraulic concrete by replacing the binding mix of concrete (cement and water) with sulfur. Sulfur is a volatile element on the lunar surface that can be extracted from lunar soils by heating. Sulfur concrete mixes were prepared to investigate the effect of extreme environmental conditions on the properties of sulfur concrete. A hypervelocity impact test was conducted, having as its target a 5-cm cubic sample of sulfur concrete. This item consisted of JSC-1 lunar regolith simulant (65%) and sulfur (35%). The sample was placed in the MSFC Impact Test Facility s Micro Light Gas Gun target chamber, and was struck by a 1-mm diameter (1.4e-03 g) aluminum projectile at 5.85 km/s. In addition, HZTERN code, provided by NASA was used to study the effectiveness of sulfur concrete when subjected to space radiation.

  11. Concrete Infrastructure Corrosion

    International Nuclear Information System (INIS)

    It is well known that many reinforced concrete structures are at risk of deterioration due to chloride ion contamination of the concrete or atmospheric carbon dioxide dissolving in water to form carbonic acid, which reacts with the concrete and the reinforcing steel. The environment within the concrete will determine the corrosion product layers, which might, inter alia, contain the oxides and/or hydroxides of iron. Tensile forces resulting from volume changes during their formation lead to the cracking and delamination of the concrete. In the present investigation the handrail of an outside staircase suffered rebar corrosion during 30 year's service, leading to severe delamination damage to the concrete structure. The railings had been sealed into the concrete staircase using a polysulphide sealant, Thiokol. The corrosion products were identified by means of Moessbauer and SEM analyses, which indicated that the corrosion product composition varied from the original steel surface to the outer layers, the former being mainly iron oxides and the latter iron oxyhydroxide.

  12. concrete5 cookbook

    CERN Document Server

    Strack, David

    2013-01-01

    The Cookbook-style recipes allow you to go both directly to your topic of interest or follow topics throughout a chapter to gain in-depth knowledge. This practical Cookbook will cater to the needs of both intermediate and advanced concrete5 developers.This book is geared towards intermediate to advanced PHP developers who would like to learn more about the concrete5 content management system. Developers already familiar with concrete5 will learn new time-saving tricks and will find the book to be a great reference tool.

  13. Concrete = aggregate, cement, water?

    International Nuclear Information System (INIS)

    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

  14. DESIGN OF ULTRA-LIGHTWEIGHT CONCRETE: TOWARDS MONOLITHIC CONCRETE STRUCTURES

    OpenAIRE

    Yu Qing Liang; Spiesz Przemek; Brouwers Jos

    2014-01-01

    This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K); and moderate m...

  15. Shrinkage Reducing Admixture for Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Concrete shrinkage cracking is a common problem in all types of concrete structures, especially for structures and environments where the cracks are prevalent and the repercussions are most severe. A liquid shrinkage reducing admixture for concrete, developed by GRACE Construction Products and ARCO Chemical Company, that reduces significantly the shrinkage during concrete drying and potentially reduces overall cracking over time.

  16. A historical examination of concrete

    International Nuclear Information System (INIS)

    The requirement that concrete in radioactive waste repositories be stable physically and chemically for very long times has initiated studies of ancient and old concretes. This report is a contribution to this effort. After a description of the history of cement and concrete, the published literature relating to the analysis of old and ancient concrete is reviewed. A series of samples spanning the history of concrete has been obtained; a variety of physical and chemical techniques have been employed to characterize these samples. Reasons for survival of ancient concretes, and for durability of early, reinforced concretes are identified. Recommendations for further studies are given. 132 refs

  17. Deterioration of PCPV concrete

    International Nuclear Information System (INIS)

    This paper presents results obtained from an experimental investigation into the deterioration of concretes used in prestressed concrete pressure vessels (PCPVs) in the UK. The experimental works were focused on the dependence of the residual properties of the thermally loaded concretes on the mix design (3 representative PCPVs), levels of exposed temperature (from 20 to 450 C), test age (3 months and 1 year) and exposure condition (sealed and unsealed). The residual properties investigated in this project were conducted by fully using both destructive (compressive, tensile splitting and static modulus) and non-destructive (dynamic modulus and ultrasonic pulse velocity) test techniques with the aim of better understanding and characterising the deterioration of PCPV concretes when subjected to both ambient and elevated temperatures under the environmental conditions likely to be experienced in real structures. Detailed statistical analyses and discussions on the experimental results were also performed and presented. (orig.)

  18. Concrete decontamination scoping tests

    International Nuclear Information System (INIS)

    This report details the research efforts and scoping tests performed at the Idaho Chemical Process Plant using scabbling, chemical, and electro-osmotic decontamination techniques on radiologically contaminated concrete

  19. Fracture Mechanics of Concrete

    DEFF Research Database (Denmark)

    Ulfkjær, Jens Peder

    Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high-strength......Chapter 1 Chapter l contains the introduction to this thesis. The scope of the thesis is partly to investigate different numerical and analytical models based on fracture mechanical ideas, which are able to predict size effects, and partly to perform an experimental investigation on high......-strength concrete. Chapter 2 A description of the factors which influence the strength and cracking of concrete and high strength concrete is made. Then basic linear fracture mechanics is outlined followed by a description and evaluation of the models used to describe concrete fracture in tension. The chapter ends...

  20. ADVANCEMENTS IN CONCRETE TECHNOLOGY

    OpenAIRE

    Shri Purvansh B. Shah; Shri Prakash D. Gohil; Shri Hiren J. Chavda; Shri Tejas D. Khediya

    2015-01-01

    Developing and maintaining world’s infrastructure to meet the future needs of industrialized and developing countries is necessary to economically grow and improve the quality of life. The quality and performance of concrete plays a key role for most of infrastructure including commercial, industrial, residential and military structures, dams, power plants. Concrete is the single largest manufactured material in the world and accounts for more than 6 billion metric tons of materials annual...

  1. High performance polymer concrete

    OpenAIRE

    Frías, M.; San-José, J. T.

    2007-01-01

    This paper studies the performance of concrete whose chief components are natural aggregate and an organic binder —a thermosetting polyester resin— denominated polymer concrete or PC. The material was examined macro- and microscopically and its basic physical and mechanical properties were determined using mercury porosimetry, scanning electron microscopy (SEM-EDAX), X-ray diffraction (XRD) and strength tests (modulus of elasticity, stress-strain curves and ultimate strengths). A...

  2. Performance of "Waterless Concrete"

    Science.gov (United States)

    Toutanji, H. A.; Grugel, R. N.

    2009-01-01

    Waterless concrete consists of molten elementary sulfur and aggregate. The aggregates in a lunar environment will be lunar rocks and soil. Sulfur is present on the Moon in Troilite soil (FeS) and, by oxidation of the soil, iron and sulfur can be produced. Sulfur concrete specimens were cycled between liquid nitrogen (approx.]91 C) and room temperature (^21 C) to simulate exposure to a lunar environment. Cycled and control specimens were subsequently tested in compression at room temperatures (^21 C) and ^-101 C. Test results showed that due to temperature cycling, the compressive strength of cycled specimens was 20% of those non-cycled. This reduction in strength can be attributed to the large differences in thermal coefficients of expansion of the materials constituting the concrete which promoted cracking. Similar sulfur concrete mixtures were strengthened with short and long glass fibres. The lunar regolith simulant was melted in a 25 cc Pt- Rh crucible in a Sybron Thermoline high temperature MoSi2 furnace at melting temperatures of 1450 to 1600 C for times of 30 min to i hour. Glass fibres and small rods were pulled from the melt. The glass fibres were used to reinforce sulfur concrete plated to improve the flexural strength of the sulfur concrete. Beams strengthened with glass fibres showed to exhibit an increase in the flexural strength by as much as 45%.

  3. Separation of contaminated concrete

    International Nuclear Information System (INIS)

    Separating the contaminated parts from the non-contaminated parts from decommissioned nuclear facilities may strongly reduce the amount of contaminated concrete. The reduction in volume of the radioactive contaminated concrete is dependent on how much cementstone is in the concrete. This research program shows that the radioactive contamination is mostly in the cementstone. However the choice that the cementstone parts, (or better said the radioactive parts) are smaller than 1 mm may not always be true. Normally the cementstone takes about 30% of the total concrete volume. A separation procedure composed by a combination of milling and thermal shock has been assessed. Both the cold and hot thermal shock in combination with milling are not able to separate the cementstone from the larger aggregates completely. However, the cementstone from the concrete with a low nominal grain size seems to be almost completely removed by the combination cold thermal shock/milling, while the cementstone from the concrete with a high nominal grain size seems to be almost completely removed by the combination hot thermal shock/milling. After both methods a layer of cementstone was still visible on the aggregates. Washing followed by a nitric acid treatment removed each 2 wt% of cementstone

  4. Translating concrete poetry Translating concrete poetry

    Directory of Open Access Journals (Sweden)

    Kirsten Malmkjaer

    2008-04-01

    Full Text Available It is interesting to examine the art form known as concrete poetry with translation -- both practical and theoretical -- in mind, because it was, according to Kopfermann (1974:x1, considered international by its creators: the language-elements are not tied to the author's mother tongue, reduction and reproduction allow elements of different languages to be combined in the scone text. The basis for this is the materiality (mostly understood in an optical or acoustic sense of the vocable° and elementary structures which are the sane in all (or at least the Indo- -European languages. This theoretical stance might suggest that it is not necessary to translate concrete poetry from one Indo-European language to another. However, most anthologies of concrete poetry contain translations and/or word glosses (see, for instance, Bann (1967, Solt (1968 and Williams (1967, so there is obviously a perceived need to provide some assistance to speakers of languages other than that in which any particular poem is composed.

  5. Offshore concrete structures

    International Nuclear Information System (INIS)

    In the offshore industry there are two possible materials for the construction of the hull of a structure; the steel and concrete, with the first one widely used until now, as in the rest of the shiphuidling industry of merchant ships, warships, etc. Materials such as aluminum, GRP or timber areused in small units with lengths lower than 100 m, and in less adverse conditions than in the offshore industry. Nevertheless, some ships/barges have been built of concrete in the past, but have been rather isolated cases which have not changed the practice in the industry. In the First and Second World War were built by the scarcity of materials, while the series of barges by Alfred A. Yee was a rare exception. Other units were also made in concrete, but almost anecdotal. Still, the behaviour of these concrete structures, especially in terms of maintenance, has been excellent. Therefore, the fact that the concrete has not had an adequate reception so far in shipbuilding, does not mean that in will not be the material best suited for the offshore industry in the future. The extra displacement and associated fuel costs in concrete ships have been found prohibitive in the past. But the loss of mobility of a concrete hull in relation to a steel hull can be perfectly offset by the advantages offered by the concrete, as the shipping and offshore industry have very different priorities. One of the main differences in these priorities is in terms of maintenance and resistance to fatigue, precisely where the concrete performs better. ships can easily be dry docked for maintenance and repair, while in the offshore platforms these works have to be done in situ so maintenance and fatigue are crucial to them. Besides these, the concrete has other advantages according to findings of several studies. And although they are interested in the conclusions that the makes as they came from people in the concrete industry, the fact that in recent years concrete offshore unit shave been built

  6. Recycled Concrete as Aggregate for Structural Concrete Production

    Directory of Open Access Journals (Sweden)

    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.

  7. Moisture profile measurements of concrete samples in vertical water flow by gamma ray transmission method

    International Nuclear Information System (INIS)

    Samples of concrete for popular habitation (0.1x0.03x0.1 m) and cellular concrete (0.1x0.05x0.1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3.7x1010 Bq, 0662 MeV) source, NaI (Tl) of 2x2'' detector coupled to gamma ray spectrometry standard electronic with multichannel analyzer and a micrometric table. For the popular habitation concrete, there was a clear correlation between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity. (author)

  8. Moisture profile measurements of concrete samples in vertical water flow by gamma ray transmission method

    Science.gov (United States)

    da Rocha, M. C.; da Silva, L. M.; Appoloni, C. R.; Portezan Filho, O.; Lopes, F.; Melquíades, F. L.; dos Santos, E. A.; dos Santos, A. O.; Moreira, A. C.; Pötker, W. E.; de Almeida, E.; Tannous, C. Q.; Kuramoto, R.; Cavalcante, F. H. de M.; Barbieri, P. F.; Caleffi, A. F.; Carbonari, B. T.; Carbonari, G.

    2001-06-01

    Samples of concrete for popular habitation (0.1×0.03×0.1 m) and cellular concrete (0.1×0.05×0.1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3.7×1010 Bq, 0662 MeV) source, Nal (Tl) of 2×2″ detector coupled to gamma ray spectrometry standard electronic with multichannel analyzer and a micrometric table. For the popular habitation concrete, there was a clear correlation between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity.

  9. Studies of historic concrete

    International Nuclear Information System (INIS)

    Underground concrete repositories for nuclear waste will have to maintain their integrity for hundreds of years. This study examines ancient concretes and assesses the suitability of equivalent modern materials for underground storage. Thirty four ancient samples have been obtained from Great Britain, Austria and Italy. One 19th century sample was also collected. The samples were examined using a variety of analytical techniques (including scanning electron microscopy, optical microscopy, chemical analysis and pH determination). The samples were also subjected to a range of physical tests. Most of the samples examined were very weak and porous although they had retained full structural integrity. With the exception of the 19th century sample, none of the concretes had maintained pH alkaline enough to immobilize radionuclides. Hydrated calcium silicates have been detected in some samples which are similar to those observed in modern Portland cement concretes. These stable cementitious species have endured for almost two thousand years. All the ancient concretes and mortars examined contained natural pozzolanic material or crushed burnt clay. This may have had some effect on the reduction in alkalinity although the main reason was full carbonation of calcium hydroxide

  10. Magnesium oxychloride cement concrete

    Indian Academy of Sciences (India)

    A K Misra; Renu Mathur

    2007-06-01

    The scope of magnesium oxychloride (MOC) cement in concrete works has been evaluated. MOC cement concrete compositions of varying strengths having good placing and finishing characteristics were prepared and investigated for their compressive and flexural strengths, -values, abrasion resistance etc. The durability of MOC concrete compositions against extreme environmental conditions viz. heating–cooling, freezing–thawing, wetting–drying and penetration and deposition of salts etc were investigated. The results reveal that MOC concrete has high compressive strength associated with high flexural strength and the ratio of compressive to flexural strength varies between 6 and 8. The elastic moduli of the compositions studied are found to be 23–85 GPa and the abrasion losses between 0.11 and 0.20%. While alternate heating–cooling cycles have no adverse effect on MOC concrete, it can be made durable against freezing–thawing and the excessive exposure to water and salt attack by replacing 10% magnesium chloride solution by magnesium sulphate solution of the same concentration.

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

    OpenAIRE

    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...

  12. Drying of Concrete

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Geiker, Mette Rica; Nygaard, Peter Vagn; Kjeldsen, Ane Mette

    Estimated and measured relative humidity (RH) change during drying are compared for two concretes, 1: w/c=0.46 and 2: w/(c+0.5fa+2sf)=0.50. The estimations were undertaken by means of the Swedish program TorkaS 1.0. Measurements were performed by RH-sensors type Humi-Guard. Drying of 150 mm thick...... samples from sides at 60% RH and 22 °C took place from 4 to 56 days after casting. At the end of the drying period the measured RH was about 4% lower than the estimated RH at 1/5th depth from the exposed surface for both concretes. In the middle of the samples, the measured RH of concretes 1 and 2 were 2...

  13. Water Entrainment in Concrete

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben

    This report gives a survey of different techniques for incorporation of designed, water-filled cavities in concrete: Water entrainment. Also an estimate of the optimum size of the water inclusions is given. Water entrainment can be used to avoid self-desiccation and self-desiccation shrinkage...... during hydration [1,26]. What is needed is some sort of container which retains the shape of the water when mixed into the concrete. The container may function based on several different physical or chemical principles. Cells and gels are examples of containers found in nature. A cell membrane provides...... a boundary to water, whereas a polymer network incorporates water in its intersticious space with its affinity due to interaction energy and polymer entropy. Such containers allow water to be stored as an entity. In relation to concrete the water encapsulation may be accomplished either before or after start...

  14. Conformity control of concrete based on the 'Concrete Family' concept

    OpenAIRE

    Caspeele, Robby; Taerwe, Luc

    2008-01-01

    This paper describes how the concept of concrete families can be used for the conformity control of concrete strength. The principles of the concept are explained and an original probabilistic evaluation is introduced. A parameter evaluation approach is explained and the guidelines and conformity criteria for concrete families in EN 206-1 are discussed.

  15. Electrokinetic decontamination of concrete

    Energy Technology Data Exchange (ETDEWEB)

    Lomasney, H. [ISOTRON Corp., New Orleans, LA (United States)

    1995-10-01

    The U.S. Department of Energy has assigned a priority to the advancement of technology for decontaminating concrete surfaces which have become contaminated with radionuclides, heavy metals, and toxic organics. This agency is responsible for decontamination and decommissioning of thousands of buildings. Electrokinetic extraction is one of the several innovative technologies which emerged in response to this initiative. This technique utilizes an electropotential gradient and the subsequent electrical transport mechanism to cause the controlled movement of ionics species, whereby the contaminants exit the recesses deep within the concrete. This report discusses the technology and use at the Oak Ridge k-25 plant.

  16. Danish High Performance Concretes

    DEFF Research Database (Denmark)

    Nielsen, M. P.; Christoffersen, J.; Frederiksen, J.

    1994-01-01

    . The paper includes the results with regard to the mix design, uni- and triaxial strength, creep, shrinkage, and chloride diffusion of HPC. The paper further gives a brief description of the bridge structures in Denmark in which HPC has been utilized. These structures include pedestrian bridges......In this paper the main results obtained in the research program High Performance Concretes in the 90's are presented. This program was financed by the Danish government and was carried out in cooperation between The Technical University of Denmark, several private companies, and Aalborg University...... fume concretes, workability, ductility, and confinement problems....

  17. Recycled aggregate concrete; an overview

    OpenAIRE

    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...

  18. Self-consolidating concrete homogeneity

    OpenAIRE

    Jarque, J. C.; Parra, C.; Valcuende, M.O.

    2007-01-01

    Concrete instability may lead to the non-uniform distribution of its properties. The homogeneity of self-consolidating concrete in vertically cast members was therefore explored in this study, analyzing both resistance to segregation and pore structure uniformity. To this end, two series of concretes were prepared, self-consolidating and traditional vibrated materials, with different w/c ratios and types of cement. The results showed that selfconsolidating concretes exhibit high resistance to...

  19. TEXTILE TECHNOLOGIES IN CONCRETE ENVIRONMENTS."

    OpenAIRE

    Morrow, Ruth; Belford, Patricia

    2007-01-01

    Girli Concrete is a cross disciplinary funded research project based in the University of Ulster involving a textile designer/ researcher, an architect/ academic and a concrete manufacturing firm.Girli Concrete brings together concrete and textile technologies, testing ideas ofconcrete as textile and textile as structure. It challenges the perception of textiles as only the ‘dressing’ to structure and instead integrates textile technologies into the products of building products. Girli Concre...

  20. Corrosion Inhibitors for Reinforced Concrete

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    Steel corrosion in reinforced concrete structures has been a major problem across the U.S. Steel-reinforced concrete structures are continually subject to attack by corrosion brought on by naturally occurring environmental conditions. FerroGard, a corrosion inhibitor, developed by Sika Corporation, penetrates hardened concrete to dramatically reduce corrosion by 65% and extend the structure's service life.

  1. Thin Concrete Barrel Vault

    NARCIS (Netherlands)

    Kamerling, M.W.

    2013-01-01

    The paper presents the structural design of a thin barrel vault constructed with Fusée Ceramique infill elements. The load transfer is analyzed and validated. For the structure composed of Fusée Ceramique elements, steel and concrete the stresses are calculated and compared to the stresses given in

  2. Electrical pulses protect concrete

    NARCIS (Netherlands)

    Van Kasteren, J.

    2006-01-01

    Even concrete is not as hard as it looks. Sea water, salt on icy roads, and indirectly even carbon dioxide from the air can corrode the steel of the reinforcing bars and so threaten the strength and integrity of a bridge pier, jetty, or viaduct. Dessi Koleva, a chemical engineer from Bulgaria, spent

  3. Concrete peeling off device

    International Nuclear Information System (INIS)

    The present invention concerns a device for peeling off activated concretes in processing for discarding a reactor of a nuclear reactor facility. The device comprises a gyrotron for generation microwaves, an irradiator for irradiating output microwaves, a reflection mirror for reflecting and converging the microwaves and irradiating them to a material to be irradiated and a first rotating means for rotating the irradiator and the reflection mirror in parallel with the axis of the gyrotron while maintaining the positional relation between the irradiator and the reflection mirror. When the position of the microwaves irradiated on concrete walls are moved in a circumferential direction and the central axes of the rotational axis and the material to be irradiated are aligned, then the intensity of the irradiation of the microwaves at each of the irradiation points can be maintained constant without changing the focal distance of the reflected microwaves thereby enabling to peel off concretes efficiently. If operation conditions are controlled based on information such as temperature at the periphery of the microwave irradiation positions, the shape and the color of the material to be irradiated and the distance to the material to be irradiated, a concrete peeling off device of high reliability can be obtained. (N.H.)

  4. Designing concrete for durability

    Directory of Open Access Journals (Sweden)

    Boyd, A. J.

    2001-12-01

    Full Text Available Some of the factors affecting the durability of modern concrete structures are discussed, with an emphasis on the problems caused by modern portland cements. This is followed by a description of some concrete durability issues of current interest, such as plastic shrinkage, seawater attack, and sulfate attack. The strategies for testing for durability are also discussed. It is concluded that, to produce durable concretes, a holistic approach to concrete construction must be adopted.

    Se discuten algunos de los factores que influyen en la durabilidad de las estructuras de hormigón modernas, haciendo énfasis en los problemas causados por el cemento Portland. A esto sigue una descripción de algunas cuestiones de interés general de la durabilidad del hormigón tales como la retracción plástica, el ataque por agua de mar y el ataque por sulfatos. Se discuten también las estrategias de los ensayos de durabilidad. Se concluye que para producir hormigones durables se debe adoptar un enfoque holístico de la construcción con hormigón.

  5. Concentrated loads on concrete

    DEFF Research Database (Denmark)

    Lorenzen, Karen Grøndahl; Nielsen, Mogens Peter

    1997-01-01

    This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas are...

  6. Continuous Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Hoang, Cao Linh; Nielsen, Mogens Peter

    1996-01-01

    This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution at the...

  7. Teaching concrete structures

    DEFF Research Database (Denmark)

    Goltermann, Per

    2014-01-01

    The teaching of concrete structures has been revised and a number of new approaches have been developed, implemented and evaluated. Inductive teaching, E-learning and “patches” have been found to be improvements and may be an inspiration and help for others development of the teaching and learning...

  8. Contaminated soil concrete blocks

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.; Limbachiya, Mukesh C.; Kew, Hsein Y.

    2009-01-01

    According to Dutch law the contaminated soil needs to be remediated or immobilised. The main focus in this article is the design of concrete blocks, containing contaminated soil, that are suitable for large production, financial feasible and meets all technical and environmental requirements. In ord

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

    Directory of Open Access Journals (Sweden)

    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.

  10. REINFORCING FIBRES AS PART OF TECHNOLOGY OF CONCRETES

    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich

    2012-07-01

    It was identified that the basalt fibre consumption rate influences both the strength and the density of products made of cellular concrete. The length of the basalt fibre impacts the strength of products. A nomogram was developed to identify the consumption rate of the basalt fibre driven by the strength of products and the Portland cement consumption rate. The authors also studied the influence of the consumption rate of Portland cement and basalt fibre onto the structural quality ratio of the foamed fibre concrete.

  11. Self-compacting concrete (SCC)

    DEFF Research Database (Denmark)

    Geiker, Mette Rica

    2008-01-01

    In many aspects Self-Compacting Concrete (SCC, “Self-Consolidating Concrete” in North America) can be considered the concrete of the future. SCC is a family of tailored concretes with special engineered properties in the fresh state. SCC flows into the formwork and around even complicated...... reinforcement arrangements under its own weight. Thus, SCC is not vibrated like conventional concrete. This drastically improves the working environment during construction, the productivity, and potentially improves the homogeneity and quality of the concrete. In addition SCC provides larger architectural...

  12. Life Cycle Assessment of Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Sjunnesson, Jeannette

    2005-09-15

    This is an environmental study on concrete that follows the standard protocol of life cycle assessment (LCA). The study is done for two types of concrete, ordinary and frost-resistant concrete, and has an extra focus on the superplasticizers used as admixtures. The utilization phase is not included in this study since the type of construction for which the concrete is used is not defined and the concrete is assumed to be inert during this phase. The results show that it is the production of the raw material and the transports involved in the life cycle of concrete that are the main contributors to the total environmental load. The one single step in the raw material production that has the highest impact is the production of cement. Within the transportation operations the transportation of concrete is the largest contributor, followed by the transportation of the cement. The environmental impact of frost-resistant concrete is between 24-41 % higher than that of ordinary concrete due to its higher content of cement. Superplasticizers contribute with approximately 0.4-10.4 % of the total environmental impact of concrete, the least to the global warming potential (GWP) and the most to the photochemical ozone creation potential (POCP). Also the toxicity of the superplasticizers is investigated and the conclusion is that the low amount of leakage of superplasticizers from concrete leads to a low risk for the environment and for humans.

  13. An historical examination of concrete

    International Nuclear Information System (INIS)

    The requirement that concrete in nuclear waste repositories be stable physically and chemically for hundreds, if not thousands, of years has initiated studies of ancient and old concretes. The history of cement and concrete is described. The oldest know concrete, from Yugoslavia, is ca. 7,500 years old. Concrete was used in many ancient civilisations, including those of Egypt, Greece and Rome. Ancient concretes were usually based upon lime, but sometimes gypsum was used. Pure lime concretes hardened by atomospheric carbonation but the Ancients, in particular the Romans, also employed hydraulic limes and discovered pozzolanas to make superior concretes which, upon hardening, contained complex cementitious hydrates including calcium-silicate-hydrate (CSH), the principal binding element in Portland cement concrete. Portland cement was not invented until 1824 or later and consists principally of calcium silicates formed by clinkerisation of a mixture of limestone and clay in carefully measured proportions. The cement sets hydraulically to form, principally, calcium hydroxide and CSH, the latter being an amorphous or semi-amorphous substance of variable composition. The published literature relating to the analysis of old and ancient cements and concretes is reviewed. A suite of samples spanning the history of concrete has been obtained. A variety of physical and chemical techniques have been employed to characterise these samples. (author)

  14. STUDY OF THE EFFECT OF ALUMINUM CONTENT AND C / S RATIO ON THE PHYSICO-MECHANICAL AND THERMAL PROPERTIES OF A LIGHTWEIGHT CONCRETE MADE FROM SAND DUNE

    Directory of Open Access Journals (Sweden)

    Z. Damene

    2015-07-01

    Full Text Available This research is a contribution to the development of local materials especially in the development of a cellular concrete with dunes sand. This is an experimental study whose objective is to see the influence of the C/S (dosage of cement compared to sand and the dosage of aluminum on the physico- mechanical and thermal performance of lightweight concrete cellular type. The results showed that the cement compared to the sand has a remarkable effect on the reaction and that on expansion the mechanical behavior as well as the dosage of aluminum in the composition of cellular concrete has a certain threshold Aluminium beyond which provides no relief benefits. Based on these results, the cellular concrete made from sand dune can be classified as light structural concrete with insulation suitable for very hot and arid environment of our region power.

  15. Micro Environmental Concrete

    Science.gov (United States)

    Lanez, M.; Oudjit, M. N.; Zenati, A.; Arroudj, K.; Bali, A.

    Reactive powder concretes (RPC) are characterized by a particle diameter not exceeding 600 μm and having very high compressive and tensile strengths. This paper describes a new generation of micro concrete, which has an initial as well as a final high physicomechanical performance. To achieve this, 15% by weight of the Portland cement have been substituted by materials rich in Silica (Slag and Dune Sand). The results obtained from the tests carried out on the RPC show that compressive and tensile strengths increase when incorporating the addition, thus improving the compactness of mixtures through filler and pozzolanic effects. With a reduction in the aggregate phase in the RPC and the abundance of the dune sand (southern of Algeria) and slag (industrial by-product of the blast furnace), the use of the RPC will allow Algeria to fulfil economical as well as ecological requirements.

  16. Reinforced concrete tomography

    International Nuclear Information System (INIS)

    In this paper we describe the technique of reinforced concrete tomography, its historical background, recent technological developments and main applications. Gamma radiation sensitive plates are imprinted with radiation going through the concrete sample under study, and then processed to reveal the presence of reinforcement and defects in the material density. The three dimensional reconstruction, or tomography, of the reinforcement out of a single gammagraphy is an original development alternative to conventional methods. Re-bar diameters and positions may be determined with an accuracy of ± 1 mm 0.5-1 cm, respectively. The non-destructive character of this technique makes it particularly attractive in cases of inhabited buildings and diagnoses of balconies. (author)

  17. Drilling waste makes concrete

    International Nuclear Information System (INIS)

    The article deals with a method of drilling waste reclamation by utilizing the converted oil-containing cuttings from the North Sea in the concrete production in Norway. The oil content is to be removed in an incineration process by heating the cuttings to about 800oC. The output capacity from the exhaust gas water cooling system is 7500 kW/hour, and is to be used in different industrial heating processes. The remaining content of pollutants in the cleaned exhaust gas outlet corresponds to the required limits with the exception of SO2 and HCl. In addition, an exhaust gas washing plant is to be installed in the near future designed for the further reduction of pollutants by 90%. The converted raw materials are used as a supplement for lessening the demand of sand and cement in the production of concrete-made pipes. 1 fig

  18. Hypervelocity impact of concrete

    International Nuclear Information System (INIS)

    Blocks of concrete and various other materials were impacted by high speed copper jets at the centre of one face, the resulting transient phenomena were measured using ultra high speed photography and various electrical signal transducers. Measurements were made of the jet velocity, penetration rate, crack velocity and initiation time, and strain pulse propagation. Post test measurements were made using electron microscopy, ultra sonics and stereoscopic photography. (orig.)

  19. Design of ultra-lightweight concrete: towards monolithic concrete structures

    Directory of Open Access Journals (Sweden)

    Yu Qing Liang

    2014-04-01

    Full Text Available This study addresses the development of ultra-lightweight concrete. A moderate strength and an excellent thermal conductivity of the lightweight concrete are set as the design targets. The designed lightweight aggregates concrete is targeted to be used in monolithic concrete façade structure, performing as both load bearing element and thermal insulator. The developed lightweight concrete shows excellent thermal properties, with a low thermal conductivity of about 0.12 W/(m·K; and moderate mechanical properties, with 28-day compressive strengths of about 10-12 N/mm . This combination of values exceeds, to the researchers’ knowledge, the performance of all other lightweight building materials. Furthermore, the developed lightweight concrete possesses excellent durability properties.

  20. Radiolysis of concrete

    International Nuclear Information System (INIS)

    A computer based radiation chemical program has been used to simulate experiments with gamma and alpha radiolysis in concrete. The experiments have been performed at Savannah River by Ned Bibler and co-workers. The calculations showed that the gas yields were very sensitive to the pH of the water phase. At a pH of 12.3 fairly good agreement was obtained between measured and calculated gas yields, assuming that the gas production only took place in the free water phase of the concrete. The following main conclusions could be made from both measurements and calculations: 1/ A steady state is obtained by gamma radiolysis of a NO3 free concrete. 2/ The yields are higher and a steady state is not obtained if NO3 is present. The yields are higher and a steady state is not obtained by alpha radiolysis. Calculations were also carried out on radiolysis from cladding hull waste stored in a cement matrix assuming both alpha and beta radiation. In the presence of an aerated gas phase a steady state pressure of more than 0.21 MPa was obtained.(author)

  1. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    OpenAIRE

    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...

  2. Repercussions on concrete permeability due to recycled concrete aggregate

    OpenAIRE

    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...

  3. Concrete Sawing Waste Recycling As Microfiller in Concrete Production

    OpenAIRE

    Bumanis, G.; Shakhmenko, G.; Kara, P; Korjakins, A.

    2015-01-01

    The main idea of the presented work is to find the ways of recycling the sawing waste/sludge in production of the new concrete. The aim of the study is to examine application of the dust-water suspension as micro filler in self-compacting concrete. In the process of sawing concrete elements a lot of dust waste is produced, the average amount being approximately 0.5-1% of the total amount of concrete. To avoid dust pollution in a production plant the sawing process is accompanied by a water st...

  4. Measurement of the wetting profile in concrete samples with vertical water by gamma radiation transmission method

    International Nuclear Information System (INIS)

    Samples of concrete for popular habitation (0,1x0,03x0,1 m) and cellular concrete (0,1x0,05x0,1 m) were submitted to water vertical ascending infiltration. The moisture content spatial and temporal evolution of each sample it was monitored in three halfway positions in a same horizontal line, applying the gamma rays transmission method. The data were taken with a 137Cs (3,7x1010 Bq, 0662 MeV) source, NaI (Tl) of 2x2' detector coupled to between wetting profiles and concrete strength. The cellular concrete showed a wetting profile compatible to its greater porosity. (author)

  5. Nanogranular origin of concrete creep

    OpenAIRE

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-01-01

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium–silicate–hydrates (C–S–H), the nano-meter sized particles that form the fundament...

  6. ASSESSMENT OF RECYCLED AGGREGATE CONCRETE

    OpenAIRE

    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...

  7. Concrete durability with antigraffiti protection

    OpenAIRE

    Neto, Elsa; Souto, Ana; Camões, Aires; Begonha, Arlindo; Cachim, Paulo

    2014-01-01

    The heritage of fair-faced concrete, largely built in the twentieth century and nowadays recognized as heritage to be protected, is susceptible to attacks by graffiti. Durability of concrete depends on the composition and characteristics of the surface, whereby it is essential to study the effects of anti-graffiti protection systems on the durability of concrete and adopt the appropriate methodology to preserve this heritage. Thus, an experimental program was developed for analyzing changes i...

  8. Inspection Strategies for Concrete Bridges

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Thoft-Christensen, Palle

    In this paper an optimal inspection strategy for concrete bridges based on periodic routine and detailed inspections is presented. The failure mode considered is corrosion of the reinforcement due to chlorides. A simple modelling of the corrosion and of the inspection strategy is presented. The...... optimal inspection strategy is determined from an optimization problem, where the design variables are time intervals between detailed inspections and the concrete cover. The strategy is illustrated on a simple structure, namely a reinforced concrete beam....

  9. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    OpenAIRE

    O. V. Anufrieva; B. H. Klochko

    2009-01-01

    The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  10. TECHNOLOGICAL PROPERTIES OF CONCRETES AND MORTARS FOR UNDERWATER CONCRETING

    Directory of Open Access Journals (Sweden)

    O. V. Anufrieva

    2009-03-01

    Full Text Available The article is about the results of experimental-and-theoretical research of usefulness of mortar and concrete mixes for underwater repair works. It is shown that the developed compositions of hydraulic engineering concretes are characterized by high effectiveness in the corrosive medium.

  11. Electrical pulses protect concrete

    OpenAIRE

    Van Kasteren, J.

    2006-01-01

    Even concrete is not as hard as it looks. Sea water, salt on icy roads, and indirectly even carbon dioxide from the air can corrode the steel of the reinforcing bars and so threaten the strength and integrity of a bridge pier, jetty, or viaduct. Dessi Koleva, a chemical engineer from Bulgaria, spent her doctoral research at the Faculty of Civil Engineering and Geosciences devising a method for the cathodic protection of steel rebars. The method is cheaper and also has fewer side effects on th...

  12. Thin Concrete Barrel Vault

    OpenAIRE

    Kamerling, M.W.

    2013-01-01

    The paper presents the structural design of a thin barrel vault constructed with Fusée Ceramique infill elements. The load transfer is analyzed and validated. For the structure composed of Fusée Ceramique elements, steel and concrete the stresses are calculated and compared to the stresses given in the codes used from 1950 to the present. The advantages and disadvantages of these low rise barrel vaults are showed. Further the possibilities of a light infill to reduce, for structures of concre...

  13. New progress in the theory and practice of heat-resisting concretes

    International Nuclear Information System (INIS)

    The main properties of heat-resistant cellular, light and heavy concretes based on high-alumina-, alumina- and Portland cements, liquid glass, alumo-phosphate binder and other binding materials containing different fine-ground additives and fillers are considered. The data of foreign and national investigations are presented concerning the effect of heating and mineral composition of cements and fine-ground mineral additions on the phase composition and structure of the cement stone and tensile properties of concretes. The foreign and national experience in the utilization of heat-resistant concretes when constructing thermal units in various branches of industry is described, as well as the economic effectiveness obtained herewith

  14. Durability of concrete in saline environment

    OpenAIRE

    1996-01-01

    Contents: - Systematic collection of field data for service life prediction of concrete structures. - Moisture in marine concrete structures - Studies in the BMV-project 1992-1996. - Scaling resistence of concrete field exposure tests. - Chloride induced corrosion in marine concrete structures. - Chloride threshold values in reinforced concrete. - A new method for determing chloride thresholds as a function of potential in field exposure tests. - Estimation of chloride ingress into concrete a...

  15. Development of Concrete Shrinkage Performance Specifications

    OpenAIRE

    Mokarem, David Wayne

    2002-01-01

    During its service life, concrete experiences volume changes. One of the types of deformation experienced by concrete is shrinkage. The four main types of shrinkage associated with concrete are plastic, autogeneous, carbonation and drying shrinkage. The volume changes in concrete due to shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, the cracking may produce a direct path for chloride ions to reach the reinforcing steel. Once chloride ions reach th...

  16. Nuclear radiation and the properties of concrete

    International Nuclear Information System (INIS)

    Concrete is used for structures in which the concrete is exposed to nuclear radiation. Exposure to nuclear radiation may affect the properties of concrete. The report mentions the types of nuclear radiation while radiation damage in concrete is discussed. Attention is also given to the effects of neutron and gamma radiation on compressive and tensile strength of concrete. Finally radiation shielding, the attenuation of nuclear radiation and the value of concrete as a shielding material is discussed

  17. Interface Microstructures in Concrete

    Directory of Open Access Journals (Sweden)

    Puertas, Francisca

    1991-03-01

    Full Text Available This paper constitutes a compilation as well as an interpretation of the present state of knowledge about the different microstructures developed in the interface areas of concrete, that is, the cement paste-aggregates, the cement paste-reinforcement, the cement paste-fiber, etc. The Chemical reactions taking place in interface areas, the development and morphology of such areas and their strength ^since interfaces are taken as the weakest points of concrete are the aspects dealt with in some detail in this work.

    El presente trabajo constituye un resumen y también una interpretación del estado actual del conocimiento respecto de las diferentes microestructuras que se desarrollan en las zonas interfaciales de los hormigones, es decir: pasta de cemento-áridos, pasta de cemento-armaduras, pasta de cemento-fibras, etc. Las reacciones químicas que tienen lugar en la zona interfacial, el desarrollo y morfología de dicha zona y su resistencia (las interfases se consideran como uno de los puntos débiles del hormigón son los aspectos que con cierto detalle se tratan en el trabajo.

  18. The concrete canister program

    International Nuclear Information System (INIS)

    In the spring of 1974, WNRE began development and demonstration of a dry storage concept, called the concrete canister, as a possible alternative to storage of irradiated CANDU fuel in water pools. The canister is a thick-walled concrete monolith containing baskets of fuel in the dry state. The decay heat from the fuel is dissipated to the environment by natural heat transfer. Four canisters were designed and constructed. Two canisters containing electric heaters have been subjected to heat loads of 2.5 times the design, ramp heat-load cycling, and simulated weathering tests. The other two canisters were loaded with irradiated fuel, one containing fuel bundles of uniform decay heat and the other containing bundles of non-uniform decay heat in a non-symmetrical radial and axial array. The collected data were used to verify the analytical tools for prediction of effectiveness of heat transfer and radiation shielding and to verify the design of the basket and canisters. The demonstration canisters have shown that this concept is a viable alternative to water pools for the storage of irradiated CANDU fuel. (author)

  19. The Concrete and Pavement Challenge

    Science.gov (United States)

    Roman, Harry T.

    2012-01-01

    The modern world is characterized by the extensive use of concrete and asphalt pavement. Periodically, these materials are replaced and the old materials disposed of. In this challenge, students will be asked to develop ways to reuse the old materials. It is important for students to understand how concrete and asphalt are made and applied, as…

  20. Wood and concrete polymer composites

    International Nuclear Information System (INIS)

    There are several ways to prepare and use wood and concrete polymer composites. The most important improvements in the case of concrete polymer composites are obtained for compressive and tensile strengths. The progress in this field in United States and other countries is discussed in this rview. (M.S.)

  1. Proportioning of light weight concrete

    DEFF Research Database (Denmark)

    Palmus, Lars

    1996-01-01

    Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory......Development of a method to determine the proportions of the raw materials in light weight concrete made with leight expanded clay aggregate. The method is based on composite theory...

  2. Revised Rules for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.; Blackmore, A.

    This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

  3. Urban Experiments and Concrete Utopias

    DEFF Research Database (Denmark)

    Andersson, Lasse

    2009-01-01

    The paper explores how concrete urban experiments can challenge the pecuniary version of the experience city and stimulate a locally rooted and democratic version of an experience based city using heterotopias and concrete utopias as the link between top down planning and bottom up experiments in...

  4. Radiographic testing in concrete structures

    International Nuclear Information System (INIS)

    The radiographic testing done in concrete structures is used to analyse the homogeneity, position and corrosion of armatures and to detect discontinuity in the concrete such as: gaps, cracks and segregations. This work develops a Image quality Indicator (IQI) with an adequated sensibility to detect discontinuites based on BS4408 norm. (E.G.)

  5. LASER ABLATION STUDIES OF CONCRETE

    Science.gov (United States)

    Laser ablation was studied as a means of removing radioactive contaminants from the surface and near-surface regions of concrete. We present the results of ablation tests on cement and concrete samples using a 1.6 kW pulsed Nd:YAG laser with fiber optic beam delivery. The laser-s...

  6. Concrete Masonry Designs: Educational Issue.

    Science.gov (United States)

    Hertzberg, Randi, Ed.

    2001-01-01

    This special journal issue addresses concrete masonry in educational facilities construction. The issue's feature articles are: (1) "It Takes a Village To Construct a Massachusetts Middle School," describing a middle school constructed almost entirely of concrete masonry and modeled after a typical small New England village; (2) "Lessons Learned,"…

  7. Structural lightweight concrete: recent research

    NARCIS (Netherlands)

    Walraven, J.; Den Uijl, J.; Stroband, J.; AI-ZubiN.; Gijsbers, J.; Naaktgeboren, M.

    1995-01-01

    As a result of a number of reasons new interest developed into the use of lightweight aggregate concrete. Within the scope of this development, a modernized code for lightweight concrete had to be written. In order to support this development, a number of research projects have been carried out. The

  8. Fatigue of Concrete Armour Units

    DEFF Research Database (Denmark)

    Sørensen, N. B.; Burcharth, H. F.; Liu, Z.

    1995-01-01

    In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed.......In the present article fatigue as a possible reason for failure of Dolosse armour units made of plain concrete is discussed....

  9. Technology Solutions Case Study: Insulating Concrete Forms

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2012-10-01

    This Pacific Northwest National Laboratory project investigated insulating concrete forms—rigid foam, hollow walls that are filled with concrete for highly insulated, hurricane-resistant construction.

  10. Study on healthcare magnetic concrete

    Institute of Scientific and Technical Information of China (English)

    YANG Yushan; DONG Faqin; FENG Jianjun

    2006-01-01

    Magnetic concrete was prepared by adding SrFe12O9 magnetic functional elementary material into concrete, and its magnetism was charged by magnetizing machine. The effect of SrFe12O9 content on magnetic field intensity and the attenuation of magnetic field intensity were investigated in different medium. The blood viscosity of rats kept in magnetic concrete was carried out. The results show that magnetic concrete can be prepared by adding SrFe12O9, and magnetic fields intensity increases with the augment of ferrite content. The attenuation of magnetic fields is mainly related with the density of medium, but it is secondary to the properties of medium. The blood viscosity of rats decreases under magnetic condition, but the blood cells remain the same as before. Experimental results support that magnetic concrete has great healthcare function.

  11. Basic principles of concrete structures

    CERN Document Server

    Gu, Xianglin; Zhou, Yong

    2016-01-01

    Based on the latest version of designing codes both for buildings and bridges (GB50010-2010 and JTG D62-2004), this book starts from steel and concrete materials, whose properties are very important to the mechanical behavior of concrete structural members. Step by step, analysis of reinforced and prestressed concrete members under basic loading types (tension, compression, flexure, shearing and torsion) and environmental actions are introduced. The characteristic of the book that distinguishes it from other textbooks on concrete structures is that more emphasis has been laid on the basic theories of reinforced concrete and the application of the basic theories in design of new structures and analysis of existing structures. Examples and problems in each chapter are carefully designed to cover every important knowledge point. As a basic course for undergraduates majoring in civil engineering, this course is different from either the previously learnt mechanics courses or the design courses to be learnt. Compa...

  12. Sodium concrete reaction: structural considerations

    International Nuclear Information System (INIS)

    An overview of the sodium concrete reaction phenomenon, with emphasis on structural considerations, is presented. Available test results for limestone, basalt, and magnetite concrete with various test article configurations are reviewed. Generally, tests indicate reaction is self limiting before all sodium is used. Uncertainties, however, concerning the mechanism for penetration of sodium into concrete have resulted in different theories about a reaction model. Structural behavior may be significant in the progression of the reaction due to thermal-structural-chemical interactions involving tensile cracking, compressive crushing, or general deterioration of concrete and the exposure of fresh concrete surfaces to react with sodium. Structural behavior of test articles and potential factors that could enhance the progression of the reaction are discussed

  13. Designing Concrete Of New Era:“Self Compacting Concrete

    Directory of Open Access Journals (Sweden)

    Dharmesh K. Bhagat

    2014-02-01

    Full Text Available In India, infrastructure is given prior importance and it is vision to make India fully developed up till 2020.But, it is a challenging job to produce high strength concrete and one of the problems for this is presence of air voids. At present to reduce these voids many compacting machines like vibrators are used in field. But, this leads to high noise pollution and annoyance the person working on site. Thus, to eliminate this problem related to compaction, strength and noise, a new concrete called Self Compacting Concrete [SCC] is used. It reduces the voids as it flows under its own weight. The strength and durability of SCC is much higher compared to conventional concrete. It also helps in achieving high quality of surface finishes and becomes sustainable as it saves the energy. But, the problem with this type of concrete is that there is no specific mix design for it. Thus, the aim of this research is to give proper methodology for the mix design of self compacting concrete and various points to be kept in mind while designing such flowable concrete.

  14. High performance polymer concrete

    Directory of Open Access Journals (Sweden)

    Frías, M.

    2007-06-01

    Full Text Available This paper studies the performance of concrete whose chief components are natural aggregate and an organic binder —a thermosetting polyester resin— denominated polymer concrete or PC. The material was examined macro- and microscopically and its basic physical and mechanical properties were determined using mercury porosimetry, scanning electron microscopy (SEM-EDAX, X-ray diffraction (XRD and strength tests (modulus of elasticity, stress-strain curves and ultimate strengths. According to the results of these experimental studies, the PC exhibited a low density (4.8%, closed pore system and a concomitantly continuous internal microstructure. This would at least partially explain its mechanical out-performance of traditional concrete, with average compressive and flexural strength values of 100 MPa and over 20 MPa, respectively. In the absence of standard criteria, the bending test was found to be a useful supplement to compressive strength tests for establishing PC strength classes.Este trabajo de investigación aborda el estudio de un hormigón de altas prestaciones, formado por áridos naturales y un aglomerante orgánico constituido por una resina termoestable poliéster, denominado hormigón polimérico HP. Se describe el material a nivel microscópico y macroscópico, presentando sus propiedades físicas y mecánicas fundamentales, mediante diferentes técnicas experimentales, tales como: porosimetría de mercurio, microscopía electrónica (SEM-EDAX, difracción de rayos X (DRX y ensayos mecánicos (módulo de elasticidad, curvas tensión- deformación y resistencias últimas. Como consecuencia del estudio experimental llevado a cabo, se ha podido apreciar cómo el HP está formado por porosidad cerrada del 4,8%, proporcionando una elevada continuidad a su microestructura interna, lo que justifica, en parte, la mejora de propiedades mecánicas respecto al hormigón tradicional, con unos valores medios de resistencia a compresión de 100

  15. SIMULATION MODELS OF RESISTANCE TO CONCRETE MOVEMENT IN THE CONCRETE CONVEYING PIPE OF THE AUTOCONCRETE PUMP

    OpenAIRE

    P. G. Anofriev

    2015-01-01

    Purpose. In modern construction the placing of concrete is often performed using distribution equipment of concrete pumps. Increase of productivity and quality of this construction work requires improvement of both concrete pumps and their tooling. The concrete pumps tooling consists of standardized concrete conveying pipes and connector bends radius of up to 2 m. A promising direction of tooling improvement is the reduce of resistance to movement of the concrete in the concrete conveying pip...

  16. Concrete Shrinkage Effect on the Composite Steel–Concrete State of Stresses

    OpenAIRE

    Moga, Petru; Alb, Claudia Pondichi

    2014-01-01

    The size of concrete shrinkage deformation depends, similar to creep, upon many factors: concrete composition, concrete quality, water/cement ratio, aggregate nature and grain size, compaction manner, humidity of ambient environment. In the steel–concrete composite structures, the phenomena of creep and shrinkage affect concrete behaviour and lead to shortening in the concrete slab. As concrete is rigidly tied to steel, the shortening is partially stopped and brings about a redistribution of ...

  17. Thermal Insulating Concrete Tiles

    Directory of Open Access Journals (Sweden)

    Sarkawt.A. Saeed

    2012-11-01

    Full Text Available This Paper studies the shape of high-thermal insulating concrete tiles used for roof tiling. The theoretical part consists of a comparison between this invented tiles and ordinary terrazzo tiles. The analysis depends on the values of thermal conductivity of the material used. The results showed that when these tiles are used for roof tiling, the temperature difference between the outside of roof surface and the inside room can be reduced about six times compared with the use of ordinary terrazzo tiles. In addition, these specimens were fabricated and tested for rupture and absorption tests. The test results showed that, they had a good resistance to the applied test loads, and high resistance to water absorption. The authors believe that, the results are remarkable, highly applicable and should be taken into consideration in building constructions.

  18. Explosive demolition of activated concrete

    International Nuclear Information System (INIS)

    This paper describes the removal of a radiologically contaminated concrete pad. This pad was removed during 1979 by operating personnel under the direction of the Waste Management Program of EG and G Idaho, Inc. The concrete pad was the foundation for the Organic Moderated Reactor Experiment (OMRE) reactor vessel located at the Idaho National Engineering Laboratory (INEL). The pad consisted of a cylindrical concrete slab 15 ft in diameter, 2 ft thick, and reinforced with steel bar. It was poured directly onto basalt rocks approximately 20 ft below grade. The entire pad contained induced radioactivity and was therefore demolished, boxed, and buried rather than being decontaminated. The pad was demolished by explosive blasting

  19. Review of concrete properties for prestressed concrete pressure vesssels

    International Nuclear Information System (INIS)

    The desire for increasing power output along with safety requirements has resulted in consideration of the prestressed concrete pressure vessel (PCPV) for most current nuclear reactor systems, as well as for the very-high-temperature reactor for process heat and as primary pressure vessels for coal conversion systems. Results are presented of a literature review to ascertain current knowledge regarding plain concrete properties under conditions imposed by a mass concrete structure such as PCRV. The effects of high temperature on such properties as strength, elasticity, and creep are discussed, as well as changes in thermal properties, multiaxial behavior, and the mechanisms thought to be responsible for the observed behavior. In addition, the effects of radiation and moisture migration are discussed. It is concluded that testing results found in the technical literature show much disagreement as to the effects of temperature on concrete properties. The variations in concrete mixtures, curing and testing procedures, age at loading, and moisture conditions during exposure and testing are some of the reasons for such disagreement. Test results must be limited, in most cases, to the materials and conditions of a given test rather than applied to such a general class of materials such as concrete. It is also concluded that sustained exposure of normal concretes to current PCRV operating conditions will not result in any significant loss of properties. However, lack of knowledge regarding effects of temperatures exceeding 1000C (2120F), moisture migration, and multiaxial behavior precludes a statement advocating operation beyond current design limits. The report includes recommendations for future research on concrete for PCPVs

  20. Durability of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place; Hansen, Kurt Kielsgaard

    The planned research will indicate, whether fibre reinforced concrete has better or worse durability than normal concrete. Durability specimens will be measured on cracked as well as uncracked specimens. Also the pore structure in the concrete will be characterized.Keywords: Fibre reinforced...... concrete, durability, pore structure, mechanical load...

  1. Betonreparationers holdbarhed (Durability of Concrete Repairs)

    DEFF Research Database (Denmark)

    Brimnes, Eydbjørn; Dali, Bogi í; Larsen, Erik Stoklund; Nielsen, Anders

    1999-01-01

    Concrete repairs on 11 pillars on bridges built in the sixties and repaired 8 to 9 years ago have been examined. Especially the chloride penetration in the repair concrete have been measured. Chloride penetration in the repair concrete is much lower than in the original concrete....

  2. Shear reinforced beams in autoclaved aerated concrete

    DEFF Research Database (Denmark)

    Cornelius, Thomas

    2010-01-01

    Shear behaviour in concrete materials is very well documented, for normal density concrete materials. In this paper results of various tests on low density concrete materials like aerated autoclaved concrete (in the following denoted aircrete) will be presented and analyzed for different combinat...

  3. Leaching of concrete : experiments and modelling

    OpenAIRE

    Ekström, Tomas

    2001-01-01

    Many concrete dams, and other concrete structures within the hydropower industry are old and in a more or less severe state of degradation. Leaching is, together with freeze-thaw, the most common degradation problem in Swedish hydraulic concrete structures. This report contains a literature survey of concrete leaching, and presents the results of an experimental determination of leaching.

  4. Substantiation of an express-method for determining the freeze-thaw resistance of cellular materials

    OpenAIRE

    S.G. Nikolskiy; O.N. Pertseva; V.I. Ivanova

    2015-01-01

    An express method for determining the freeze-thaw resistance of cellular materials was offered and substantiated in this article. The proposed measurement technology of concrete frost resistance is based on the computation of the value z which is the ratio of the relative decrease of compression resistance R to the relative permanent set ε in the direction which is perpendicular to the pressure. It was found that this ratio is constant for a given composition of the concrete and does not depe...

  5. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    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.

  6. Concrete density estimation by rebound hammer method

    Energy Technology Data Exchange (ETDEWEB)

    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.

  7. Concrete density estimation by rebound hammer method

    International Nuclear Information System (INIS)

    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

  8. The Tectonic Potentials of Concrete

    DEFF Research Database (Denmark)

    Egholm Pedersen, Ole

    2013-01-01

    industrial paradigm of standardization, have been put forward. This development is carried forward by computers and digital fabrication, but has yet to find its way into the production of building components. With regards to concrete casting, however, existing research do offer advancement towards an...... increased customisation of casting moulds. The hypothesis of this research is that the techniques used in this research do not fully address the tectonic potentials of concrete which gives rise to the primary research question: Is it possible to enhance existing or develop new concrete casting techniques...... which allows for individualisation and resource optimisation, while matching or enhancing the tectonic potentials found in existing, repetitive concrete casting techniques? The research is comprised of two modes of inquiry: an empirical study of contemporary casting methods and subsequently six case...

  9. Tests on standard concrete samples

    CERN Multimedia

    CERN PhotoLab

    1973-01-01

    Compression and tensile tests on standard concrete samples. The use of centrifugal force in tensile testing has been developed by the SB Division and the instruments were built in the Central workshops.

  10. Nondestructive testing of concrete structures

    International Nuclear Information System (INIS)

    Nondestructive testing of concrete is highly inhomogeneous which makes it cumbersome to setup experimental procedures and analyze experimental data. However, recent research and development activities have discovered the different methods of NDT, like the electromagnetic method, ultrasonic pulse velocity test, pulse echo/impact echo test, infrared thermography, radar or short pulse radar techniques, neutron and gamma radiometry, radiography, carbonation test and half-cell potential method available for NDT of concrete structures. NDT of concrete is emerging as a useful tool for quality control and assurance. This papers also describes the more common NDT methods discussed during the two-week course on 'Nondestructive Testing of Concrete Structures', held at the Malaysian Institute for Nuclear Technology Research (MINT) in Malaysia, which was jointly organized by MINT and the International Atomic Energy Agency (IAEA)

  11. Contaminated concrete surface layer removal

    International Nuclear Information System (INIS)

    Equipment is being developed to economically remove contaminated concrete surfaces in nuclear facilities. To be effective this equipment should minimize personnel radiation exposure, minimize the volume of material removed, and perform the operation quickly with the least amount of energy. Several methods for removing concrete surfaces are evaluated for use in decontaminating such facilities. Two unique methods especially suited for decontamination are described: one, the water cannon, is a device that fires a high-velocity jet of fluid causing spallation of the concrete surface; the other, a concrete spaller, is a tool that exerts radial pressure agains the sides of a pre-dilled shallow cylindrical hole causing spallation to occur. Each method includes a means for containing airborne contamination. Results of tests show that these techniques can rapidly and economically remove surfaces, and leave minimal rubble for controlled disposal

  12. Electrically conductive polymer concrete overlays

    Science.gov (United States)

    Fontana, J. J.; Webster, R. P.

    1984-08-01

    The use of cathodic protection to prevent the corrosion of reinforcing steel in concrete structures has been well established. Application of a durable, skid-resistant electrically conductive polymer concrete overlay would advance the use of cathodic protection for the highway industry. Laboratory studies indicate that electrically conductive polymer concrete overlays using conductive fillers, such as calcined coke breeze, in conjunction with polyester or vinyl ester resins have resistivities of 1 to 10 ohm-cm. Both multiple-layer and premixed mortar-type overlays were made. Shear bond strengths of the conductive overlays to concrete substrates vary from 600 to 1300 psi, with the premixed overlays having bond strengths 50 to 100% higher than the multiple-layer overlays.

  13. Let’s Get Concrete!

    DEFF Research Database (Denmark)

    Jones, Candace; Boxenbaum, Eva

    whereas in the United States market and professional logics interacted: manufacturers cooperated to create standards for concrete and appealed to architects as consumers. Our findings also illuminate that concrete was legitimated initially by imitation of stone, but this strategy soon de-legitimated not......Scholars emphasize the cognitive or ideational aspects of institutional logics. Less clear is the role of materiality, which is a key aspect of institutional logics, and aesthetic responses to material objects. This study focuses on the introduction of a new building material—concrete— during 1890...... to 1939 in the architectural profession. Our findings reveal that how professional logics were enacted drove different process for incorporating concrete as a legitimate building material: in France professional and state logics combined to create regulations that governed architects’ use of concrete...

  14. The behaviour of concrete structures in fire

    OpenAIRE

    Fletcher, Ian A; Welch, Stephen; Torero, Jose L; Carvel, Ricky O; Usmani, Asif

    2007-01-01

    The nature of concrete-based structures means that they generally perform very well in fire. However, concrete is a complex material and its properties can change dramatically when exposed to high temperatures. This paper provides a ‘state of the art’ review of research into the effects of high temperature on concrete and concrete structures, extending to a range of forms of construction, including novel developments. The principal effects of fire on concrete are loss of compressive strength ...

  15. A Research About the Concrete Compression Failure

    OpenAIRE

    Deliang Meng; Huijian Li; Lixin Zhang; Pin Cheng

    2013-01-01

    Concrete material is one of the wide applications materials in the engineering. There is an important implication on national life safety to research its destruction. And size effect of the concrete also has an important impact on failure mechanism and strain injury of the concrete. There are many influencing factors on concrete size effect. In this paper, we will use the numerical simulation method to research the concrete compression failure from two aspects. One is the arrangement of th...

  16. Metrology Needs for Predicting Concrete Pumpability

    OpenAIRE

    Myoungsung Choi; Ferraris, Chiara F.; Martys, Nicos S.; Didier Lootens; Bui, K.; H. R. Trey Hamilton

    2015-01-01

    With the increasing use of pumping to place concrete, the development and refinement of the industry practice to ensure successful concrete pumping are becoming important needs for the concrete construction industry. To date, research on concrete pumping has been largely limited to a few theses and research papers. The major obstacle to conduct research on concrete pumping is that it requires heavy equipment and large amounts of materials. Thus, developing realistic and simple measurement tec...

  17. Analysis of concrete slabs supported on soil

    OpenAIRE

    Barros, Joaquim A. O.

    1999-01-01

    A numerical model for material non-linear analysis of concrete slabs supported on soil is described in this work. In this model, the cracked concrete is regarded as cracks with concrete between cracks. The behaviour of the concrete between cracks is simulated by the conventional theory of plasticity. The behaviour of the cracks is defined by their constitutive laws using the concrete fracture properties. Smeared multifixed and rotating crack models are available in the model. ...

  18. Development of concrete shrinkage performance specifications

    OpenAIRE

    Mokarem, David W.; Meyerson, Richard M.; Weyers, Richard E.

    2003-01-01

    During its service life, concrete undergoes volume changes. One of the types of deformation is shrinkage. The four main types of shrinkage associated with concrete are plastic, autogenous, carbonation, and drying shrinkage. The volume changes in concrete due to shrinkage can lead to the cracking of the concrete. In the case of reinforced concrete, the cracking may produce a direct path for chloride ions to reach the reinforcing steel. Once chloride ions reach the steel surface, the steel will...

  19. Concrete production analysis for hydrotechnical structure

    OpenAIRE

    Zupančič, Jože

    2009-01-01

    The thesis deals with the production of concrete in the concrete mixing plant HB 2000 and the project of construction of hydroelectric power plant Krško. In the first stage, the thesis offers a general description of different types of concrete mixing plants and a manner of verification of production abilities of concrete mixing plants in Slovenija for assuring quality where control examinations play one of the essential parts in preventive measures at assuring quality concrete mixes. It also...

  20. Sustainable Concrete with Recycled Aggregate

    OpenAIRE

    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...

  1. Environmentally friendly, customised sprayed concrete

    OpenAIRE

    Río, Olga

    2010-01-01

    The quality of structural shotcrete or sprayed concrete depends not only on the Same factors as conventional structural concrete, but also on other placement-related issues such as pumping or spraying. Although today's primarily prescriptive design and control tools guarantee quality to some extent, the results are uncertain and mix design procedures do not provide sound information, a priori", on mechanical properties or durabllity. Nor does this approach contribute to design or produce spra...

  2. Concrete waterproofing in nuclear industry.

    Science.gov (United States)

    Scherbyna, Alexander N; Urusov, Sergei V

    2005-01-01

    One of the main points of aggregate safety during the transportation and storage of radioactive materials is to supply waterproofing for all constructions having direct contact with radiating substances and providing strength, seismic shielding etc. This is the problem with all waterside structures in nuclear industry and concrete installations in the treatment and storage of radioactive materials. In this connection, the problem of developing efficient techniques both for the repair of operating constructions and the waterproofing of new objects of the specified assignment is genuine. Various techniques of concrete waterproofing are widely applied in the world today. However, in conditions of radiation many of these techniques can bring not a profit but irreparable damage of durability and reliability of a concrete construction; for instance, when waterproofing materials contain organic constituents, polymers etc. Application of new technology or materials in basic construction elements requires in-depth analysis and thorough testing. The price of an error might be very large. A comparative analysis shows that one of the most promising types of waterproofing materials for radiation loaded concrete constructions is "integral capillary systems" (ICS). The tests on radiation, thermal and strength stability of ICS and ICS-treated concrete samples were initiated and fulfilled in RFNC-VNIITF. The main result is--ICS applying is increasing of waterproofing and strength properties of concrete in conditions of readiation The paper is devoted to describing the research strategy, the tests and their results and also to planning of new tests. PMID:16604701

  3. Concrete waste reduction of 50%

    International Nuclear Information System (INIS)

    During decommissioning quite a volume of concrete waste is produced. The degree of activation of the waste can range from clearly activated material to slightly activated or contaminated concrete. The degree of activation influences the applicable waste management processes that can be applied. The subsequent waste management processes can be identified for concrete waste are; disposal, segregation, re-use, conditional release and release. With each of these steps, the footprint of radioactive decommissioning waste is reduced. Future developments for concrete waste reduction can be achieved by applying smart materials in new build facilities (i.e. fast decaying materials). NRG (Nuclear Research and consultancy Group) has investigated distinctive waste management processes to reduce the foot-print of concrete waste streams resulting from decommissioning. We have investigated which processes can be applied in the Netherlands, both under current legislation and with small changes in legislation. We have also investigated the separation process in more detail. Pilot tests with a newly patented process have been started in 2015. We expect that our separation methods will reduce the footprint reduction of concrete waste by approximately 50% due to release or re-use in the nuclear sector or in the conventional industry. (authors)

  4. Modelling cellular behaviour

    Science.gov (United States)

    Endy, Drew; Brent, Roger

    2001-01-01

    Representations of cellular processes that can be used to compute their future behaviour would be of general scientific and practical value. But past attempts to construct such representations have been disappointing. This is now changing. Increases in biological understanding combined with advances in computational methods and in computer power make it possible to foresee construction of useful and predictive simulations of cellular processes.

  5. Intravital FRET: Probing Cellular and Tissue Function in Vivo.

    Science.gov (United States)

    Radbruch, Helena; Bremer, Daniel; Mothes, Ronja; Günther, Robert; Rinnenthal, Jan Leo; Pohlan, Julian; Ulbricht, Carolin; Hauser, Anja E; Niesner, Raluca

    2015-01-01

    The development of intravital Förster Resonance Energy Transfer (FRET) is required to probe cellular and tissue function in the natural context: the living organism. Only in this way can biomedicine truly comprehend pathogenesis and develop effective therapeutic strategies. Here we demonstrate and discuss the advantages and pitfalls of two strategies to quantify FRET in vivo-ratiometrically and time-resolved by fluorescence lifetime imaging-and show their concrete application in the context of neuroinflammation in adult mice. PMID:26006244

  6. Intravital FRET: Probing Cellular and Tissue Function in Vivo

    OpenAIRE

    Helena Radbruch; Daniel Bremer; Ronja Mothes; Robert Günther; Jan Leo Rinnenthal; Julian Pohlan; Carolin Ulbricht; Hauser, Anja E.; Raluca Niesner

    2015-01-01

    The development of intravital Förster Resonance Energy Transfer (FRET) is required to probe cellular and tissue function in the natural context: the living organism. Only in this way can biomedicine truly comprehend pathogenesis and develop effective therapeutic strategies. Here we demonstrate and discuss the advantages and pitfalls of two strategies to quantify FRET in vivo—ratiometrically and time-resolved by fluorescence lifetime imaging—and show their concrete application in the context o...

  7. Cellular Resolutions of Ideals Defined by Simplicial Homomorphisms

    CERN Document Server

    Braun, Benjamin; Klee, Steven

    2011-01-01

    In this paper we introduce the class of ordered homomorphism ideals and prove that these ideals admit minimal cellular resolutions constructed as homomorphism complexes. As a key ingredient of our work, we introduce the class of cointerval simplicial complexes and investigate their combinatorial and topological properties. As a concrete illustration of these structural results, we introduce and study nonnesting monomial ideals, an interesting family of combinatorially defined ideals.

  8. Evaluation of the Concrete Contribution Factor for Composite Sections with Lightweight Concrete under Axial Compression

    OpenAIRE

    Yasser M. Hunaiti; Nabil M. Falah; Issam M. Assi

    2002-01-01

    Tests on hollow steel tubes of square, rectangular and circular sections filled with foamed concrete and lightweight aggregate concrete were conducted to investigate the contribution of these concretes to the strength of cross sections of composite short columns. In addition, these tests aims at understanding the behavior of short columns with lightweight concrete. Thirty short column specimens filled with foamed concrete and lightweight aggregate concrete were tested in this investigation. F...

  9. Comparison of Performance of Standard Concrete And Fibre Reinforced Standard Concrete Exposed To Elevated Temperatures

    OpenAIRE

    K. Srinivasa Rao

    2013-01-01

    Concrete elements exposed to fire undergo temperature gradients and as a result, undergo physical changes or spalling which leads to expose steel reinforcement. This causes distress in concrete structures. The performance of concrete can be improved with the addition of steel fibres to concrete especially when it is exposed to heat. Therefore, this study has been carried out to generate experimental data on standard concrete ofgrade M45 and Fiber Reinforced Standard Concrete exposed to elevat...

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

    OpenAIRE

    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...

  11. Drying of concrete. Part II: The drying time of concrete structures

    DEFF Research Database (Denmark)

    Hansen, Kurt Kielsgaard; Christensen, Søren Lolk

    1998-01-01

    The composition of a concrete mix has a significant influence on the drying time to reach a given relative humidity in the concrete pores. Knowledge of the influence on the drying of a specific component in the concrete makes it possible to design a concrete mix having a predetermined drying time....... In the paper the effects of the air content and the silica fume content on the drying time are investigated on two concrete mixes having different water/cement ratios. One concrete represents a normal concrete and the other represents a selfdesiccation concrete....

  12. Heterogeneous cellular networks

    CERN Document Server

    Hu, Rose Qingyang

    2013-01-01

    A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses,  covering the related topics including scenarios of heterogeneous network deployment, interference management i

  13. Cellular Reflectarray Antenna

    Science.gov (United States)

    Romanofsky, Robert R.

    2010-01-01

    The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

  14. Nanogranular origin of concrete creep.

    Science.gov (United States)

    Vandamme, Matthieu; Ulm, Franz-Josef

    2009-06-30

    Concrete, the solid that forms at room temperature from mixing Portland cement with water, sand, and aggregates, suffers from time-dependent deformation under load. This creep occurs at a rate that deteriorates the durability and truncates the lifespan of concrete structures. However, despite decades of research, the origin of concrete creep remains unknown. Here, we measure the in situ creep behavior of calcium-silicate-hydrates (C-S-H), the nano-meter sized particles that form the fundamental building block of Portland cement concrete. We show that C-S-H exhibits a logarithmic creep that depends only on the packing of 3 structurally distinct but compositionally similar C-S-H forms: low density, high density, ultra-high density. We demonstrate that the creep rate ( approximately 1/t) is likely due to the rearrangement of nanoscale particles around limit packing densities following the free-volume dynamics theory of granular physics. These findings could lead to a new basis for nanoengineering concrete materials and structures with minimal creep rates monitored by packing density distributions of nanoscale particles, and predicted by nanoscale creep measurements in some minute time, which are as exact as macroscopic creep tests carried out over years. PMID:19541652

  15. 304 Concretion facility closure plan

    International Nuclear Information System (INIS)

    The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium Zircaloy-2 and copper silicon alloy, uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets in the 304 Concretion Facility, located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Concretion Facility (304 Facility). Clean closure of the 304 Facility is the proposed method for closure of the facility. Justification for this proposal is presented. 15 refs., 22 figs., 4 tabs

  16. Cellular oncogenes in neoplasia.

    OpenAIRE

    Chan, V T; McGee, J O

    1987-01-01

    In recent years cellular homologues of many viral oncogenes have been identified. As these genes are partially homologous to viral oncogenes and are activated in some tumour cell lines they are termed "proto-oncogenes". In tumour cell lines proto-oncogenes are activated by either quantitative or qualitative changes in gene structure: activation of these genes was originally thought to be a necessary primary event in carcinogenesis, but activated cellular oncogenes, unlike viral oncogenes, do ...

  17. Cellular Cardiomyoplasty: Clinical Application

    OpenAIRE

    Chachques, J. (J.); Acar, C; J. Herreros; Trainini, J. (Jorge); Prosper, F.; D’Attellis, N. (N.); Fabiani, J. N.; Carpentier, A

    2004-01-01

    Myocardial regeneration can be induced with the implantation of a variety of myogenic and angiogenic cell types. More than 150 patients have been treated with cellular cardiomyoplasty worldwide, 18 patients have been treated by our group. Cellular cardiomyoplasty seems to reduce the size and fibrosis of infarct scars, limit postischemic remodelling, and restore regional myocardial contractility. Techniques for skeletal myoblasts culture and ex vivo expansion using auto...

  18. HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

    Directory of Open Access Journals (Sweden)

    O. M. Pshinko

    2015-08-01

    Full Text Available Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic–viscous–plastic bodies. The system of canonical equations consists of the equations for concrete strength, absolute volume, concrete mix consistency as well as the equation for optimal concrete saturation with aggregates while minimizing cement content. The joint solution of these four equations related to composition allows determining for the materials the concrete composition of required strength, concrete workability with minimum cement content. The procedure for calculation of hydraulic concrete composition according to the physico-analytical method consists of two parts: 1 physical, which is laboratory testing of concrete mix components in different concrete compositions; 2 analytical, which represents the calculation algorithm for concrete compositions equivalent in concrete strength and workability that comply with the specific conditions of concrete placing. Findings. To solve the problem of designing the concrete composition with the desired properties for railway structures and buildings it was proposed to use the information technology in the form of a developed computer program whose algorithm includes the physico-analytical method for hydraulic concrete composition determination. Originality. The developed concrete composition design method takes into account the basic properties of raw materials, concrete mix and concrete, which are pre-determined. The distinctive feature of physico-analytical method is obtaining of a set of equivalent compositions with a certain concrete mix

  19. Performance test on shielding concrete

    International Nuclear Information System (INIS)

    The cylinder of the shielding concrete is made from common Portland cement and home-made coarse or fine aggregates. Orthogonal design experiment and regression analysis are adopted to study the effects of the water content, sand percentage and water-cement ratio on the property of shielding concrete and the difference between them. The test shows that the tensile strength is in inverse proportion with water-cement ratio, and the influence is quite significant. Another factor is the type of aggregates. The effect of the age on its density is not obvious. Similarly, the concrete shielding γ rays shares the same influencing factors with that shielding neutron rays on density, slump and tensile strength. And both have the same change rules regarding to mechanical property. (authors)

  20. Bending characteristics of resin concretes

    Directory of Open Access Journals (Sweden)

    Ribeiro Maria Cristina Santos

    2003-01-01

    Full Text Available In this research work the influence of composition and curing conditions in bending strength of polyester and epoxy concrete is analyzed. Various mixtures of resin and aggregates were considered in view of an optimal combination. The Taguchi methodology was applied in order to reduce the number of tests, and in order to evaluate the influence of various parameters in concrete properties. This methodology is very useful for the planning of experiments. Test results, analyzed by this methodology, shown that the most significant factors affecting bending strength properties of resin concretes are the type of resin, resin content and charge content. An optimal formulation leading to a maximum bending strength was achieved in terms of material parameters.

  1. Design of buried concrete encasements

    International Nuclear Information System (INIS)

    The operation of many Department of Energy (DOE) sites requires the transfer of radioactive liquid products from one location to another. DOE Order 6430.1A requires that the transfer pipelines be designed and constructed so that any leakage can be detected and contained before it reaches the environment. One design option often considered to meet this requirement is to place the pipeline in a stainless steel-lined, buried concrete encasement. This provides the engineer with the design challenge to integrate standard structural design principles with unique DOE requirements. The complete design of a buried concrete encasement must consider seismic effects, leak detection, leak confinement, radiation shielding, thermal effects, pipe supports, and constructability. This paper contains a brief discussion of each of these design considerations, based on experience gained during the design of concrete encasements for the Process Facilities Modifications (PFM) project at Hanford

  2. Flexural behavior of reinforced concrete beams: Comparative analysis between high-performance concrete and ordinary concrete

    Directory of Open Access Journals (Sweden)

    Hamrat Mostefa

    2014-04-01

    Full Text Available This paper presents an experimental study on the flexural strength of reinforced concrete beams made with high performance concrete (HPC and ordinary concrete (OC. We are carried an experimental campaign aimed comes in three points: 1- the study of the law of behavior of the two materials (OC and HPC, 2- the influence of the compressive strength of concrete and the rate of longitudinal reinforcement on the loaddeflection behavior and ductility index, 3- comparative analysis (ACI318, Eurocode 2 and BS8110 against the crack opening. Test results showed that the capacity of the beams in HPC is higher (6% to 20 % than the beams in OC. The use of HPC is more efficient than the OC to delay the first cracking. The average value of the ductility index for the beams in HPC is 1.30 times those beams in OC. The formula for calculating the crack opening derived of the Eurocode 2 gives the best prediction the crack width of beams (for both types of concrete.

  3. Reliability Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Middleton, C. R.

    This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the details of a methodology which can be used to generate Whole Life (WL) reliability...... profiles. These WL reliability profiles may be used to establish revised rules for concrete bridges. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

  4. Concrete with Highly Active Rice Husk Ash

    Institute of Scientific and Technical Information of China (English)

    FENG Qing-ge; LIN Qing-yu; YU Qi-jun; ZHAO San-ying; YANG Lu-feng; Shuichi Sugita

    2004-01-01

    The overall aim was to investigate the effect of highly active rice husk ash (RHA) produced by an industrial furnace on some properties of concrete. The strength, pore volume and pore distribution of concrete and the Ca(OH)2 content in concrete were investigated by JIS A 1108 (Method of test for compressive strength of concrete), a mercury instrument porosimeter, and the thermogravimetric analysis, respectively. The results show that,with RHA replacement of cement,the compressive strength of concrete is increased evidently;the average pore radius of concrete is greatly decreased, especially the portion of the pores greater than 20nm in radius is decreased while the amount of smaller pores is increased, and the more the RHA replacement, the less the amount of Ca(OH)2 in concrete. The latter two results are the main reasons for the strength enhancement of concrete.

  5. Topology optimization of reinforced concrete structures

    DEFF Research Database (Denmark)

    Amir, Oded

    Recent advances regarding topology optimization procedures of reinforced concrete structures are presented. We discuss several approaches to the challenging problem of optimizing the distribution of concrete and steel reinforcement. In particular, the consideration of complex nonlinear constituti...

  6. High Performance Concrete Pavement in Indiana

    OpenAIRE

    Nantung, Tommy E

    2011-01-01

    Until the early 1990s, curling and warping of Portland cement concrete pavement did not concern pavement engineers in many transportation agencies. Since beginning construction of the interstate system in the United States in the late 1950s through the late 1980s, the performance of Portland cement concrete pavement has been associated with properties of concrete as a pavement material. In those years developed standards and design guidelines emphasized better concrete materials and construct...

  7. Some Properties of concretes containing recycled aggregates

    OpenAIRE

    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. Critical Study of Corrosion Damaged Concrete Structures

    OpenAIRE

    Sallehuddin Shah Ayop; John Cairns

    2013-01-01

    Corrosion of steel reinforcement in concrete is one of the major problems with respect to the durability of reinforced concrete structures. The degradation of the structure strength due to reinforcement corrosion decreases its design life. This paper presents the literature study on the influence of the corrosion on concrete structure starting from the mechanism of the corrosion until the deterioration stage and the structural effects of corrosion on concrete structures.

  9. Nanoparticles for high performance concrete (HPC)

    OpenAIRE

    Torgal, Fernando Pacheco; Miraldo, Sérgio; Ding, Yining; Labrincha, J. A.

    2013-01-01

    According to the 2011 ERMCO statistics, only 11% of the production of ready-mixed concrete relates to the high performance concrete (HPC) target. This percentage has remained unchanged since at least 2001 and appears a strange choice on the part of the construction industry, as HPC offers several advantages over normal-strength concrete, specifically those of high strength and durability. It allows for concrete structures requiring less steel reinforcement and offers a longer serviceable life...

  10. Rapid-1 Hardening Accelerator Concrete Admixture

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    SIKA Rapid-1 is a concrete admixture that allows the development of very early high strengths in concrete consisting of commonly used mix components. Unlike concrete set accelerators, it does not reduce set time or long-term strength, and it does not corrode steel reinforcing. This hardening accelerator allows placement of fresh concrete without early stiffening, followed by a period of very rapid strength gain after initial set.

  11. Self Compacting Concrete And Its Properties

    OpenAIRE

    Mahesh, S.

    2014-01-01

    Self-compacting concrete (SCC), which flows under its own weight and doesn’t require any external vibration for compaction, has revolutionized concrete placement. Such concrete should have relatively low yield value to ensure high flow ability, a moderate viscosity to resists segregation and bleeding and must maintain its homogeneity during transportation, placing and curing to ensure adequate structural performance and long term durability. Self-compacting concrete (SCC) ca...

  12. Influence of Silica Fume on Normal Concrete

    OpenAIRE

    Debabrata Pradhan

    2013-01-01

    The incorporation of silica fume into the normal concrete is a routine one in the present days to produce the tailor made high strength and high performance concrete. The design parameters are increasing with the incorporation of silica fume in conventional concrete and the mix proportioning is becoming complex. The main objective of this paper has been made to investigate the different mechanical properties like compressive strength, compacting factor, slump of concrete incorporating silica ...

  13. Research on ZWR Concrete Energy Saving Synergist

    OpenAIRE

    Hu Zhigang

    2015-01-01

    ZWR concrete energy saving synergist used in commodity concrete, were carried out experimental research and engineering application. The results show that the energy-boosters, in ensuring the overall performance of the concrete situation, as its content is 0.6% to 1% in cementitious material can reduce the amount of cement by 10% to 15%, significantly reduces production costs. Without changing the working properties and structural performance of the concrete, this energy saving synergist can ...

  14. Concrete with mineral and chemical addition

    International Nuclear Information System (INIS)

    In the article interpretation of basic result research of cement concrete on astringent with grind wastage flotation concrete florin ore. Prove that introduction the highest wastage in composition astringent in quantitative to 20% from the masses of cement allowed find physical-technical description of concrete. More elective is Mark that, complex introduction in composition of astringent wastage of production florin and chemical plasticizer that will do contribute to acceleration velocity of hydrate wedge mineral of cement and forming strong structure of concrete

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

    OpenAIRE

    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...

  16. 9 CFR 91.26 - Concrete flooring.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Concrete flooring. 91.26 Section 91.26... LIVESTOCK FOR EXPORTATION Inspection of Vessels and Accommodations § 91.26 Concrete flooring. (a) Pens aboard an ocean vessel shall have a 3 inch concrete pavement, proportioned and mixed to give 2000...

  17. Prediction of Deterioration of Concrete Bridges

    NARCIS (Netherlands)

    Gaal, G.C.M.

    2004-01-01

    In the early 20th century, the general idea was that concrete structures would never show deterioration. However, in the 1990s concrete structures showed an increase in number of cracks and area of spalling. Especially spalling of the concrete cover could create a harmful situation to the users. Spa

  18. Significance of tests and properties of concrete and concrete-making materials

    CERN Document Server

    Pielert, James H

    2006-01-01

    Reflects a decade of technological changes in concrete industry! The newest edition of this popular ASTM publication reflects the latest technology in concrete and concrete-making materials. Six sections cover: (1) General information on the nature of concrete, sampling, variability, and testing laboratories. A new chapter deals with modeling cement and concrete properties. (2) Properties of freshly mixed concrete. (3) Properties of hardened concrete. (4) Concrete aggregates—this section has been revised and the chapters are presented in the order that most concerns concrete users: grading, density, soundness, degradation resistance, petrographic examination, reactivity, and thermal properties. (5) Materials other than aggregates—the chapter on curing materials now reflects the current technology of materials applied to new concrete surfaces. The chapter on mineral admixtures has been separated into two chapters: supplementary cementitious materials and ground slag. (6) Specialized concretes—contains a ...

  19. Computational modeling of concrete flow

    DEFF Research Database (Denmark)

    Roussel, Nicolas; Geiker, Mette Rica; Dufour, Frederic; Thrane, Lars Nyholm; Szabo, Peter

    2007-01-01

    This paper provides a general overview of the present status regarding computational modeling of the flow of fresh concrete. The computational modeling techniques that can be found in the literature may be divided into three main families: single fluid simulations, numerical modeling of discrete...

  20. Study of Recycled Concrete Aggregates

    OpenAIRE

    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.

  1. Early Reading and Concrete Operations.

    Science.gov (United States)

    Polk, Cindy L. Howes; Goldstein, David

    1980-01-01

    Indicated that early readers are more likely to be advanced in cognitive development than are nonearly-reading peers. After one year of formal reading instruction, early readers maintained their advantage in reading achievement. Measures of concrete operations were found to predict reading achievement for early and nonearly readers. (Author/DB)

  2. Novel techniques for concrete curing

    DEFF Research Database (Denmark)

    Kovler, Konstantin; Jensen, Ole Mejlhede

    2005-01-01

    lightweight aggregate, superabsorbent polymers or water-soluble chemicals, which reduce water evaporation (so called "internal sealing"). These concepts have been intensively researched in the 90s, but still are not widespread among contractors and concrete suppliers. The differences between conventional...

  3. Large Scale Glazed Concrete Panels

    DEFF Research Database (Denmark)

    Bache, Anja Margrethe

    2010-01-01

    Factories and finally Lene Tranberg and Bøje Lungård’s Elsinore water purification plant. These buildings have qualities that I would like applied, perhaps transformed or most preferably, if possible, interpreted anew, for the large glazed concrete panels I shall develop. The article is ended and concluded...

  4. Timber-concrete composite beams

    NARCIS (Netherlands)

    Van der Linden, M.L.R.

    1999-01-01

    In this paper an easy-to-use design model for timber-concrete composite beams is discussed. The model is applicable for computer simulations as well as for hand calculations. A research programme was started in 1992 in co-operation with the University of Karlsruhe, to study the loadbearing capacitie

  5. Timber floors strengthened with concrete

    NARCIS (Netherlands)

    Blass, H.J.; Linden, M.L.R. van der; Schlager, M.

    1998-01-01

    Timber-concrete composite (tcc) beams may be used for the renovation of old timber floors. Although these systems are not new (Pokulka, 1997) and form a simple and practical solution, they are not widely adopted. One of the reasons for this is the Jack of uniform design rules. In this research progr

  6. Early Property Development in Concrete

    DEFF Research Database (Denmark)

    Normann, Gitte; Munch-Petersen, Christian

    2014-01-01

    The Freiesleben Maturity function is widely used for planning of execution. We tested if for concrete with and without fly ash. The test showed surprisingly that the maturity function in general is not valid. We found that curing at high temperature gave a significant decrease in strength. Fly ash...

  7. A Failure Criterion for Concrete

    DEFF Research Database (Denmark)

    Ottosen, N. S.

    1977-01-01

    A four-parameter failure criterion containing all the three stress invariants explicitly is proposed for short-time loading of concrete. It corresponds to a smooth convex failure surface with curved meridians, which open in the negative direction of the hydrostatic axis, and the trace in the devi...

  8. Irregular Cellular Learning Automata.

    Science.gov (United States)

    Esnaashari, Mehdi; Meybodi, Mohammad Reza

    2015-08-01

    Cellular learning automaton (CLA) is a recently introduced model that combines cellular automaton (CA) and learning automaton (LA). The basic idea of CLA is to use LA to adjust the state transition probability of stochastic CA. This model has been used to solve problems in areas such as channel assignment in cellular networks, call admission control, image processing, and very large scale integration placement. In this paper, an extension of CLA called irregular CLA (ICLA) is introduced. This extension is obtained by removing the structure regularity assumption in CLA. Irregularity in the structure of ICLA is needed in some applications, such as computer networks, web mining, and grid computing. The concept of expediency has been introduced for ICLA and then, conditions under which an ICLA becomes expedient are analytically found. PMID:25291810

  9. Architected Cellular Materials

    Science.gov (United States)

    Schaedler, Tobias A.; Carter, William B.

    2016-07-01

    Additive manufacturing enables fabrication of materials with intricate cellular architecture, whereby progress in 3D printing techniques is increasing the possible configurations of voids and solids ad infinitum. Examples are microlattices with graded porosity and truss structures optimized for specific loading conditions. The cellular architecture determines the mechanical properties and density of these materials and can influence a wide range of other properties, e.g., acoustic, thermal, and biological properties. By combining optimized cellular architectures with high-performance metals and ceramics, several lightweight materials that exhibit strength and stiffness previously unachievable at low densities were recently demonstrated. This review introduces the field of architected materials; summarizes the most common fabrication methods, with an emphasis on additive manufacturing; and discusses recent progress in the development of architected materials. The review also discusses important applications, including lightweight structures, energy absorption, metamaterials, thermal management, and bioscaffolds.

  10. Cellular Homeostasis and Aging.

    Science.gov (United States)

    Hartl, F Ulrich

    2016-06-01

    Aging and longevity are controlled by a multiplicity of molecular and cellular signaling events that interface with environmental factors to maintain cellular homeostasis. Modulation of these pathways to extend life span, including insulin-like signaling and the response to dietary restriction, identified the cellular machineries and networks of protein homeostasis (proteostasis) and stress resistance pathways as critical players in the aging process. A decline of proteostasis capacity during aging leads to dysfunction of specific cell types and tissues, rendering the organism susceptible to a range of chronic diseases. This volume of the Annual Review of Biochemistry contains a set of two reviews addressing our current understanding of the molecular mechanisms underlying aging in model organisms and humans. PMID:27050288

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

    OpenAIRE

    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...

  12. Effects of Concrete on Propagation Characteristics of Guided Wave in Steel Bar Embedded in Concrete

    OpenAIRE

    Zhupeng Zheng; Ying Lei

    2014-01-01

    Techniques based on ultrasonic guided waves (UGWs) play important roles in the structural health monitoring (SHM) of large-scale civil infrastructures. In this paper, dispersion equations of longitudinal wave propagation in reinforced concrete member are investigated for the purpose of monitoring steels embedded in concrete. For a steel bar embedded in concrete, not the velocity but the attenuation dispersion curves will be affected by the concrete. The effects of steel-to-concrete shear modu...

  13. Fatigue Strain and Damage Analysis of Concrete in Reinforced Concrete Beams under Constant Amplitude Fatigue Loading

    OpenAIRE

    Fangping Liu; Jianting Zhou

    2016-01-01

    Concrete fatigue strain evolution plays a very important role in the evaluation of the material properties of concrete. To study fatigue strain and fatigue damage of concrete in reinforced concrete beams under constant amplitude bending fatigue loading, constant amplitude bending fatigue experiments with reinforced concrete beams with rectangular sections were first carried out in the laboratory. Then, by analyzing the shortcomings and limitations of existing fatigue strain evolution equation...

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

    OpenAIRE

    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. Wireless Cellular Mobile Communications

    Directory of Open Access Journals (Sweden)

    V. Zalud

    2002-12-01

    Full Text Available In this article is briefly reviewed the history of wireless cellularmobile communications, examined the progress in current secondgeneration (2G cellular standards and discussed their migration to thethird generation (3G. The European 2G cellular standard GSM and itsevolution phases GPRS and EDGE are described somewhat in detail. Thethird generation standard UMTS taking up on GSM/GPRS core network andequipped with a new advanced access network on the basis of codedivision multiple access (CDMA is investigated too. A sketch of theperspective of mobile communication beyond 3G concludes this article.

  16. Translating partitioned cellular automata into classical type cellular automata

    OpenAIRE

    Poupet, Victor

    2008-01-01

    Partitioned cellular automata are a variant of cellular automata that was defined in order to make it very simple to create complex automata having strong properties such as number conservation and reversibility (which are often difficult to obtain on cellular automata). In this article we show how a partitioned cellular automaton can be translated into a regular cellular automaton in such a way that these properties are conserved.

  17. Elastic-plastic constitutive modeling of concrete

    International Nuclear Information System (INIS)

    The need to understand concrete behavior under high temperatures in the nuclear industry has become rather accute. For this purpose, a constitutive model of concrete especially developed for this severe environment is indispensable. This report reviews the presently available constitutive models of concrete at standard-temperature conditions and considers their advantages and drawbacks. A rather simple but effective approach is selected to treat concrete behavior at high temperatures. Special emphasis is devoted to the modeling of concrete up to and including failure. The derived constitutive model is checked with biaxial and triaxial benchmark experimental results. Very good agreement is obtained

  18. Mechanical characterization of fiber reinforced Polymer Concrete

    Directory of Open Access Journals (Sweden)

    João Marciano Laredo dos Reis

    2005-09-01

    Full Text Available A comparative study between epoxy Polymer Concrete plain, reinforced with carbon and glass fibers and commercial concrete mixes was made. The fibers are 6 mm long and the fiber content was 2% and 1%, respectively, in mass. Compressive tests were performed at room temperature and load vs. displacement curves were plotted up to failure. The carbon and glass fibers reinforcement were randomly dispersed into the matrix of polymer concrete. An increase in compressive properties was observed as function of reinforcement. The comparison also showed that Polymer Concrete, plain and reinforced, has a better performance than regular market concrete, suggesting that PC is a reliable alternative for construction industry.

  19. Concrete structures protection, repair and rehabilitation

    CERN Document Server

    Woodson, R Dodge

    2009-01-01

    The success of a repair or rehabilitation project depends on the specific plans designed for it. Concrete Structures: Protection, Repair and Rehabilitation provides guidance on evaluating the condition of the concrete in a structure, relating the condition of the concrete to the underlying cause or causes of that condition, selecting an appropriate repair material and method for any deficiency found, and using the selected materials and methods to repair or rehabilitate the structure. Guidance is also provided for engineers focused on maintaining concrete and preparing concrete investigation r

  20. Strength of Concrete Containing Basalt Fibre

    Directory of Open Access Journals (Sweden)

    Parvez Imraan Ansari

    2015-04-01

    Full Text Available This paper presents the comparative study of effect of basalt fibre on compressive and split tensile strength of M40 grade concrete. The basalt fibre was mixed in concrete by (0.5%, 1%, and 1.5% of its total weight of cement in concrete. Results indicated that the strength increases with increase of basalt fibre content up to 1.0% beyond that there is a reduction in strength on increasing basalt fibre. The results show that the concrete specimen with 1.0% of basalt fibre gives better performance when it compared with 0.5%and 1.5% basalt fibre mix in concrete specimens.

  1. Genetic Dominance & Cellular Processes

    Science.gov (United States)

    Seager, Robert D.

    2014-01-01

    In learning genetics, many students misunderstand and misinterpret what "dominance" means. Understanding is easier if students realize that dominance is not a mechanism, but rather a consequence of underlying cellular processes. For example, metabolic pathways are often little affected by changes in enzyme concentration. This means that…

  2. The New Cellular Immunology

    Science.gov (United States)

    Claman, Henry N.

    1973-01-01

    Discusses the nature of the immune response and traces many of the discoveries that have led to the present state of knowledge in immunology. The new cellular immunology is directing its efforts toward improving health by proper manipulation of the immune mechanisms of the body. (JR)

  3. Estimation of Concrete's Porosity by Ultrasounds

    Science.gov (United States)

    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.

  4. Durable fiber reinforced self-compacting concrete

    International Nuclear Information System (INIS)

    In order to produce thin precast elements, a self-compacting concrete was prepared. When manufacturing these elements, homogenously dispersed steel fibers instead of ordinary steel-reinforcing mesh were added to the concrete mixture at a dosage of 10% by mass of cement. An adequate concrete strength class was achieved with a water to cement ratio of 0.40. Compression and flexure tests were carried out to assess the safety of these thin concrete elements. Moreover, serviceability aspects were taken into consideration. Firstly, drying shrinkage tests were carried out in order to evaluate the contribution of steel fibers in counteracting the high concrete strains due to a low aggregate-cement ratio. Secondly, the resistance to freezing and thawing cycles was investigated on concrete specimens in some cases superficially treated with a hydrophobic agent. Lastly, both carbonation and chloride penetration tests were carried out to assess durability behavior of this concrete mixture

  5. Organisms adaptable concrete. Eco-concrete for fresh water area; Seibutsu to kyoseisuru eco-concrete. Tansuiiki taiogata eco-concrete

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. Designing Concrete Of New Era:“Self Compacting Concrete

    OpenAIRE

    Dharmesh K. Bhagat; Nandan H. Dawda

    2014-01-01

    In India, infrastructure is given prior importance and it is vision to make India fully developed up till 2020.But, it is a challenging job to produce high strength concrete and one of the problems for this is presence of air voids. At present to reduce these voids many compacting machines like vibrators are used in field. But, this leads to high noise pollution and annoyance the person working on site. Thus, to eliminate this problem related to compaction, strength and noise,...

  7. Control of Early Age Concrete. Phase 3: Creep in Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Hansen, Per Freiesleben;

    1997-01-01

    The mechanical properties of the "Road Directorate Concrete" at early ages are studied. Creep in tension at 24 and 72 maturity hours are measured on dogbone shaped specimens. The development of tensile modulus of elasticity and strength are measured with a method developed here. The results are...... compared to compression values and splitting strengths. It is found that the properties of creep in tension are similar to the properties in compression. Further the influence form temperature on creep is found to be significant....

  8. Self-consolidating concrete homogeneity

    Directory of Open Access Journals (Sweden)

    Jarque, J. C.

    2007-08-01

    Full Text Available Concrete instability may lead to the non-uniform distribution of its properties. The homogeneity of self-consolidating concrete in vertically cast members was therefore explored in this study, analyzing both resistance to segregation and pore structure uniformity. To this end, two series of concretes were prepared, self-consolidating and traditional vibrated materials, with different w/c ratios and types of cement. The results showed that selfconsolidating concretes exhibit high resistance to segregation, albeit slightly lower than found in the traditional mixtures. The pore structure in the former, however, tended to be slightly more uniform, probably as a result of less intense bleeding. Such concretes are also characterized by greater bulk density, lower porosity and smaller mean pore size, which translates into a higher resistance to pressurized water. For pore diameters of over about 0.5 μm, however, the pore size distribution was found to be similar to the distribution in traditional concretes, with similar absorption rates.En este trabajo se estudia la homogeneidad de los hormigones autocompactantes en piezas hormigonadas verticalmente, determinando su resistencia a la segregación y la uniformidad de su estructura porosa, dado que la pérdida de estabilidad de una mezcla puede conducir a una distribución no uniforme de sus propiedades. Para ello se han fabricado dos tipos de hormigones, uno autocompactante y otro tradicional vibrado, con diferentes relaciones a/c y distintos tipos de cemento. Los resultados ponen de manifiesto que los hormigones autocompactantes presentan una buena resistencia a la segregación, aunque algo menor que la registrada en los hormigones tradicionales. A pesar de ello, su estructura porosa tiende a ser ligeramente más uniforme, debido probablemente a un menor sangrado. Asimismo, presentan una mayor densidad aparente, una menor porosidad y un menor tamaño medio de poro, lo que les confiere mejores

  9. Automatic dam concrete placing system; Dam concrete dasetsu sagyo no jidoka system

    Energy Technology Data Exchange (ETDEWEB)

    Yoneda, Y.; Hori, Y.; Nakayama, T.; Yoshihara, K.; Hironaka, T. [Okumura Corp., Osaka (Japan)

    1994-11-15

    An automatic concrete placing system was developed for concrete dam construction. This system consists of the following five subsystems: a wireless data transmission system, an automatic dam concrete mixing system, a consistency determination system, an automatic dam concrete loading and transporting system, and a remote concrete bucket opening and closing system. The system includes the following features: mixing amount by mixing ratio and mixing intervals can be instructed from a concrete placing site by using a wireless handy terminal; concrete is mixed automatically in a batcher plant; a transfer car is started, and concrete is charged into a bucket automatically; the mixed concrete is determined of its properties automatically; labor cost can be reduced, the work efficiency improved, and the safety enhanced; and the system introduction has resulted in unattended operation from the aggregate draw-out to a bunker line, manpower saving of five persons, and reduction in cycle time by 10%. 11 figs., 2 tabs.

  10. Designing of concrete diamond sawblade

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shao-he; DING Xin-yu; ZHOU Jia-xiang

    2005-01-01

    By analyzing the abrasive theory of concrete diamond sawblade, the proposal that the diamond should be selected by its function in cutting concrete is presented. The part of the big grit diamonds cut rock, and the part of the small grit diamonds improve the wearability of the matrix. The contrast tests are done with different shapes of sawbaldes in split segment, slant "U" slot segment, sandwich segment, turbo segment and three-slot segment. The special shapes of sawblades can improve the effect of cooling and the removing ability of the rock powder. The data of tests show that the efficiency of cutting and the life of sawblades are improved by designing the diamond prescription and using the especial geometry of segment.

  11. Radionuclide Retention in Concrete Wasteforms

    Energy Technology Data Exchange (ETDEWEB)

    Bovaird, Chase C.; Jansik, Danielle P.; Wellman, Dawn M.; Wood, Marcus I.

    2011-09-30

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. The information present in the report provides data that (1) measures the effect of concrete wasteform properties likely to influence radionuclide migration; and (2) quantifies the rate of carbonation of concrete materials in a simulated vadose zone repository.

  12. Introduction to concrete curing effect on the early performance of modern concrete

    Directory of Open Access Journals (Sweden)

    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.

  13. Viscoelastic behavior of concrete pile

    Institute of Scientific and Technical Information of China (English)

    丁科; 唐小弟

    2008-01-01

    Based on constitutive theory of viscoelasticity,the viscoelastic behaviour of concrete pile was investigated.The influence of viscosity coefficient on the stress,displacement and velocity response was discussed.With the increase of viscosity coefficient,the amplitude of stress wave decreases,and the maximum value of the stress wave shifts to deeper position of the pile.In other words,the viscosity coefficient behaves as lag effect to stress wave.

  14. Severe ASR damaged concrete bridges

    DEFF Research Database (Denmark)

    Antonio Barbosa, Ricardo; Gustenhoff Hansen, Søren

    2015-01-01

    Technical University of Denmark (DTU) and University of Southern Denmark (SDU) have conducted several full-scale experiments with severe ASR deteriorated bridges. This paper presents few and preliminary results from both the shear tests and the measuring of the material properties. The shear tests...... show that the shear capacity is almost unaffected of ASR despite significant reduction in compressive concrete strength. Furthermore, measurements show a significant tensile reinforcement strain developed due to ASR expansion....

  15. Resonance Testing of Asphalt Concrete

    OpenAIRE

    Gudmarsson, Anders

    2014-01-01

    This thesis present novel non-destructive laboratory test methods to characterize asphalt concrete. The testing is based on frequency response measurements of specimens where resonance frequencies play a key role to derive material properties such as the complex modulus and complex Poisson’s ratio. These material properties are directly related to pavement quality and used in thickness design of pavements. Since conventional cyclic loading is expensive, time consuming and complicated to perfo...

  16. Molecular and Cellular Signaling

    CERN Document Server

    Beckerman, Martin

    2005-01-01

    A small number of signaling pathways, no more than a dozen or so, form a control layer that is responsible for all signaling in and between cells of the human body. The signaling proteins belonging to the control layer determine what kinds of cells are made during development and how they function during adult life. Malfunctions in the proteins belonging to the control layer are responsible for a host of human diseases ranging from neurological disorders to cancers. Most drugs target components in the control layer, and difficulties in drug design are intimately related to the architecture of the control layer. Molecular and Cellular Signaling provides an introduction to molecular and cellular signaling in biological systems with an emphasis on the underlying physical principles. The text is aimed at upper-level undergraduates, graduate students and individuals in medicine and pharmacology interested in broadening their understanding of how cells regulate and coordinate their core activities and how diseases ...

  17. Quality evaluation of aged concrete by ultrasound

    Science.gov (United States)

    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.

  18. Very heavy iron-punching concretes

    International Nuclear Information System (INIS)

    The present report deals with all the heavy iron-punching concretes, metallic wastes produced by the transformation industry. After a detailed description of the physical properties of metallic aggregates, a classification of heavy mortars is given, into three main categories: steel-shot grouts d = 5,3 - 6; steel-shot grouts mixed with a mineral d = 3,7 - 4,2; injection heavy grouts d = 3,5 - 4. The following chapter describes iron-punching concretes the most used in the atomic industry: iron-punching concretes mixed with cast-iron - iron-punching concretes mixed with magnetite; iron-punching concretes mixed with barite; iron-punching concretes mixed with limonite; iron-punching concretes mixed with boron. The compositions of these concretes are given together with their physical and mechanical characteristics. Numerous diagrams make it possible to find rapidly the proportions of the constituents of these concretes as a function of the required density. Technical advice and specifications are given in an appendix together with a bibliography of these heavy concretes. (author)

  19. Experimental Studies on Glass Fiber Concrete

    Directory of Open Access Journals (Sweden)

    J.D.Chaitanya kumar

    2016-06-01

    Full Text Available Concrete is one of the most widely recognized development material for the most part delivered by utilizing locally accessible ingredients. The development of concrete has brought about the essential need for additives both chemical and mineral to improve the performance of concrete. Hence varieties of admixtures such as fly ash, coconut fibre have been used so far. Hence an attempt has been made in the present investigation to study the behaviour of glass fibre in concrete. The present trend in concrete technology is towards increasing the strength and durability of concrete to meet the demands of the modern construction. The main aim of the study is to study the effect of glass fibre in the concrete. Glass fibre has the high tensile strength and fire resistant properties thus reducing the loss of damage during fire accidents. The addition of these fibres into concrete can dramatically increase the compressive strength, tensile strength and split tensile strength of the concrete. In this study, tests have done for the concrete with glass fibre of 0.5%, 1%, 2% and 3% of cement by adding as an admixture

  20. Addressing concrete cracking in NPPs

    International Nuclear Information System (INIS)

    The phenomenon of concrete cracking is one of the most frequently encountered deterioration at NPPs as it has been shown by a wide Survey of NPPs performed by IAEA in 1994-95 It can be due to a multitude of causes such as the normal ageing process (shrinkage, creep, prestressing force loss) as well as exposure to the environment (temperature variation, moisture, freeze/thaw, etc) The above mentioned Survey has also shown that in 64% of cases, no action was taken or required. It became also obvious that there is a lack of guidance as when remedial actions are needed. The paper describes, with the help of a Flow Chart, the various stages to be considered, from the first step of identification of cracks, to the definition of causes, evaluation of extent of damage, evaluation of effect/implications (safety, reliability), to the final step of deciding if repair action is required. Finally, based upon a wide literature survey the paper proposes in a Chart format, Criteria for addressing concrete cracks in NPPs., when taking in considerations all these factors. This paper discusses the process which should lead to the selection of an effective repair method and proposes, based upon worldwide standards and literature, criteria which should lead to the decision whether to repair or not concrete cracks, after the cracks have been identified and evaluated, addressing the entire range of aspects involved. (author)

  1. Cement and concrete options paper

    International Nuclear Information System (INIS)

    Greenhouse gas emissions associated with the production of concrete are projected to increase from 10.5 million tonnes in 1990 to almost 14 million tonnes in 2010. Over half of this amount will be non-energy related emissions of carbon dioxide resulting from the conversion of limestone to lime. According to this report by industry experts, the industry has an excellent record of improving energy efficiency and there are few easy gains remaining. Nevertheless, improvements in energy efficiency and fuel use, increased use of concrete where it can be shown to result in net reduction of GHG emissions, and partial replacement of cement by supplementary cementitious materials that involve no additional generation of GHGs, could yield an approximate reduction in carbon dioxide emissions of nearly seven million tons in 2010. The industry proposes three measures to realise these benefits: (1) encouraging replacement of fossil fuels by otherwise waste material, (2) encouraging increased use of concrete in constructing houses and roads, and (3) encouraging increased use of supplementary cementing materials. The industry is opposed to carbon or energy taxes that increase the cost of doing business, on the grounds that such taxes would adversely affect the industry's competitive position internationally. tabs

  2. Electromagnetic cellular interactions

    Czech Academy of Sciences Publication Activity Database

    Cifra, Michal; Fields, J. S.; Farhadi, A.

    2011-01-01

    Roč. 105, č. 3 (2011), 223-246. ISSN 0079-6107. [36th International Congress of Physiological Sciences (IUPS2009). Kyoto, 27.07.2009-01.08.2009] R&D Projects: GA ČR(CZ) GPP102/10/P454 Institutional research plan: CEZ:AV0Z20670512 Keywords : bioelectric phenomena * cellular biophysics Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.203, year: 2011

  3. Magnetic Cellular Switches

    OpenAIRE

    Overby, Darryl R.; Alenghat, Francis J.; Montoya-Zavala, Martín; Bei, HuCheng; Oh, Philmo; Karavitis, John; Ingber, Donald E.

    2004-01-01

    This paper focuses on the development of magnetic cellular switches to enable magnetic control of intracellular functions in living mammalian cells, including receptor signal transduction and gene transcription. Our approach takes advantage of the mechanosensitivity of adenosine 3′,5′-monophosphate (cAMP) induction and downstream transcription controlled by the cAMP regulatory element (CRE) to engineer gene constructs that optically report gene expression in living cells. We activate transcri...

  4. Cellular therapy in Tuberculosis

    Directory of Open Access Journals (Sweden)

    Shreemanta K. Parida

    2015-03-01

    Full Text Available Cellular therapy now offer promise of potential adjunct therapeutic options for treatment of drug-resistant tuberculosis (TB. We review here the role of Mesenchymal stromal cells, (MSCs, as well as other immune effector cells in the therapy of infectious diseases with a focus on TB. MSCs represent a population of tissue-resident non-hematopoietic adult progenitor cells which home into injured tissues increase the proliferative potential of broncho-alveolar stem cells and restore lung epithelium. MSCs have been shown to be immune-modulatory and anti-inflammatory mediated via cell-cell contacts as well as soluble factors. We discuss the functional profile of MSCs and their potential use for adjunct cellular therapy of multi-drug resistant TB, with the aim of limiting tissue damage, and to convert unproductive inflammatory responses into effective anti-pathogen directed immune responses. Adjunct cellular therapy could potentially offer salvage therapy options for patients with drug-resistant TB, increase clinically relevant anti-M.tuberculosis directed immune responses and possibly shorten the duration of anti-TB therapy.

  5. Cellular therapy in tuberculosis.

    Science.gov (United States)

    Parida, Shreemanta K; Madansein, Rajhmun; Singh, Nalini; Padayatchi, Nesri; Master, Iqbal; Naidu, Kantharuben; Zumla, Alimuddin; Maeurer, Markus

    2015-03-01

    Cellular therapy now offer promise of potential adjunct therapeutic options for treatment of drug-resistant tuberculosis (TB). We review here the role of Mesenchymal stromal cells, (MSCs), as well as other immune effector cells in the therapy of infectious diseases with a focus on TB. MSCs represent a population of tissue-resident non-hematopoietic adult progenitor cells which home into injured tissues increase the proliferative potential of broncho-alveolar stem cells and restore lung epithelium. MSCs have been shown to be immune-modulatory and anti-inflammatory mediated via cell-cell contacts as well as soluble factors. We discuss the functional profile of MSCs and their potential use for adjunct cellular therapy of multi-drug resistant TB, with the aim of limiting tissue damage, and to convert unproductive inflammatory responses into effective anti-pathogen directed immune responses. Adjunct cellular therapy could potentially offer salvage therapy options for patients with drug-resistant TB, increase clinically relevant anti-M.tuberculosis directed immune responses and possibly shorten the duration of anti-TB therapy. PMID:25809753

  6. Thermophysical characteristics of low density autoclaved aerated concrete and their influence on durability of exterior walls of buildings

    Directory of Open Access Journals (Sweden)

    A.B. Krutilin

    2015-03-01

    Full Text Available The paper presents the results of experimental studies of thermophysical characteristics of autoclaved aerated concrete with density of 400 and 500 kg/m3. The dependence of thermal conductivity on temperature and humidity was determined. The boundary humidities were set for which ice is either not formed or its amount is negligible in the pores of the materials at the temperature below zero. The new method of non-isothermal liquid transport coefficient determination was suggested. It was found that one of the basic mechanisms of moving water for cellular concrete samples with a moisture content over 30 % by weight is non-isothermal liquid transport. The effect of humidity on durability of exterior walls is estimated according to cellular concrete frost-resistance tests.

  7. CONCRETE DURABILITY Through High Volume Fly ash Concrete (HVFC A Literature review

    Directory of Open Access Journals (Sweden)

    VANITA AGGARWAL

    2010-09-01

    Full Text Available The application of concrete in construction is as old as the days of Greek and roman civilization. But for numerous easons, the concrete construction industry is not sustainable. It consumes a lot of virgin materials and the principal raw material of concrete i.e. cement is responsible for green house gas emissions causing a threat to environment through global warming. Therefore, the industry has seen various types of concrete in search of a solution to sustainable development. Infrastructural growth has witnessed many forms of concrete like High Strength Concrete, High Performance Concrete, Self Compacting Concrete and the latest in the series is High Volume Fly Ash Concrete (HVFC. The paradigm has shifted from one property to other of concrete with advancement in technology. The construction techniques have been modernized with focus on high strength, dense and uniform surface texture, more reliable quality, improved durability and faster construction. This paper discusses the development of high volume fly ash concrete for construction with reference to its predecessors like HSC and HPC. The literature available on use of fly ash in concrete has been extensively searched for getting a platform for the start of research on use of high volumes of fly ash in concrete pavements.

  8. Environment Aware Cellular Networks

    KAUST Repository

    Ghazzai, Hakim

    2015-02-01

    The unprecedented rise of mobile user demand over the years have led to an enormous growth of the energy consumption of wireless networks as well as the greenhouse gas emissions which are estimated currently to be around 70 million tons per year. This significant growth of energy consumption impels network companies to pay huge bills which represent around half of their operating expenditures. Therefore, many service providers, including mobile operators, are looking for new and modern green solutions to help reduce their expenses as well as the level of their CO2 emissions. Base stations are the most power greedy element in cellular networks: they drain around 80% of the total network energy consumption even during low traffic periods. Thus, there is a growing need to develop more energy-efficient techniques to enhance the green performance of future 4G/5G cellular networks. Due to the problem of traffic load fluctuations in cellular networks during different periods of the day and between different areas (shopping or business districts and residential areas), the base station sleeping strategy has been one of the main popular research topics in green communications. In this presentation, we present several practical green techniques that provide significant gains for mobile operators. Indeed, combined with the base station sleeping strategy, these techniques achieve not only a minimization of the fossil fuel consumption but also an enhancement of mobile operator profits. We start with an optimized cell planning method that considers varying spatial and temporal user densities. We then use the optimal transport theory in order to define the cell boundaries such that the network total transmit power is reduced. Afterwards, we exploit the features of the modern electrical grid, the smart grid, as a new tool of power management for cellular networks and we optimize the energy procurement from multiple energy retailers characterized by different prices and pollutant

  9. Behavior of Foamed Concrete under Quasi State Indentation Test: Indenter Size Effects

    Directory of Open Access Journals (Sweden)

    Mohd Zairul Affindy

    2011-05-01

    Full Text Available Quasi static indentation test is a method consist of applying a compressive axial load using head of indenter to moulded cylinders at a rate which is within a prescribe range until failure occurs. The behaviour of foamed concrete under indentation test should behave like cellular material behavior. The Stress-strain behavior can be divided into three regimes, elastic regime, plateau regime and densification regime. There is still less research conducted toward foamed concrete under indentation test. It is stated that the standard method to obtain the compressive strength of foamed concrete based on ASTM C39 standard or BS 1881: Part 116:1983 is not captured the true compressive strength of foamed concrete. The compressive strength typically achieved low compressive strength and not behaves like a cellular material behavior. This result is due brittle collapse of the sample. Previous study has shows the compressive strength under indentation test is higher and created a localized deformation. Besides, there is a densified zone created below the indenter region which is end with hemi-spherical shape. . Tear line occur because of exrended in front of the indenter and perpendicular to the indenter surface. This study aims to investigate further about the behavior of foamed concrete. This study was look about effect of densities and size of indenter on behavior of foamed concrete under indentation test. The density used is low density, medium density and high density. Size of indenter used is 20mm, 30mm, 50mm and 70.5mm. Under indentation test, the higher densities, the higher compressive strength and the bigger size of indenter used, the strength is decreased due to the early crack initiation and propagation. It is important to know the ratio used to make sure indentation test is captured the true strength.

  10. Durability of cracked fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    fibre reinforcement are exposed to a combination of mechanical and environmental load to indicate whether fibre reinforcement will improve the durability of cracked concrete structures. Secondly, it is the aim to identify important mechanisms for the effect of the fibre reinforcement on the durability......Durability studies are carried out at BKM as part of the research project "Design Methods for Fibre Reinforced Concrete" (FRC) involving BKM, The Concrete Research Center at DTI, Building Technology at Aalborg University, Rambøll, 4K-Beton and Rasmussen & Schiøtz. Concrete beams with or without...... pore structure are made on specimens drilled or sawed from beams after unloading (mechanical load). The pore structure of the concretes will be studied by microscopy, sorption and suction curves. The test programme involves three different concrete qualities (water-cement ratios). Both steel fibres (ZP...

  11. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard-Nielsen, Anders Boe; Damkilde, Lars; Freiesleben Hansen, Per

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete which includes the transitional thermal effect. The model govern both early age concrete and hardened concrete. The development of the material properties in the model are assumed to depend on the...... imbalance in the microstructure termed the microprestresses, which reduces the stiffness of the concrete and increase the creep rate. The aging material is modelled in an incremental way reflecting the hydration process in which new layers of cement gel solidifies in a stress free state and add stiffness to...

  12. Transitional Thermal Creep of Early Age Concrete

    DEFF Research Database (Denmark)

    Hauggaard, A. B.; Damkilde, L.; Hansen, Per Freiesleben

    1999-01-01

    Couplings between creep of hardened concrete and temperature/water effects are well-known. Both the level and the gradients in time of temperature or water content influence the creep properties. In early age concrete the internal drying and the heat development due to hydration increase the effect...... of these couplings. The purpose of this work is to set up a mathematical model for creep of concrete that includes the transitional thermal effect. The model governs both early age concrete and hardened concrete. The development of the material properties in the model is assumed to depend on the...... imbalance in the microstructure termed the microprestresses, which reduce the stiffness of the concrete and increase the creep rate. The aging material is modeled in an incremental way reflecting the hydration process in which new layers of cement gel solidify in a stress free state and add stiffness to the...

  13. Rotational Capacity of Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Ulfkjær, J. P.; Henriksen, M. S.; Brincker, Rune;

    1995-01-01

    The European Structural Integrity Society-Technical Committee 9, has initiated a Round Robin on 'Scale Effects and Transitional Failure Phenomena of Reinforced Concrete Beams in Flexure'. In Denmark, Aalborg University is participating. The programme for Aalborg University involves an experimental...... programme where 120 reinforced concrete beams, 54 plain concrete beams and 324 concrete cylinders are tested. For the reinforced concrete beams four different parar meters are varied. The slenderness is 6, 12 and 18, the beam depth is 100 mm, 200 mm and 400 mm giving nine different geometries, five...... reinforcement ratios between 0.14% and 1.57%, and the concrete has a compressive strength of approximately 60 MPa or 90 MPa. The beams are tested in threepoint bending in a servo controlled materials testing system specially designed for the wide range of geometries The casting of the beams is finished. The...

  14. Modelling the Loss of Steel-Concrete Bonds in Corroded Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    The existing stochastic models for deterioration of reinforced concrete structures is extended by adding modelling of "loss of bond" due to corrosion between the reinforcement bars and the surrounding concrete....

  15. The long-term properties of concrete used in prestressed concrete pressure vessels

    International Nuclear Information System (INIS)

    Data are presented on the late-life properties of concretes used in prestressed concrete pressure vessels (PCPV) and containment structures. The effects of ageing under simulated PCPV conditions are discussed. (author)

  16. Open to a Changing World: Concrete Poetry in Denmark

    DEFF Research Database (Denmark)

    Ørum, Tania

    The essay describes the rise of concrete poetry in Denmark in the 1960s, the intermedial roots of concrete poetry, concrete poetry as open work (in Eco's sense), the main Danish poets, the development of concrete poetry into systemic writing and the longer cultural perspectives of concrete poetry...

  17. Recycled aggregate concrete exposed to elevated temperature

    OpenAIRE

    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,...

  18. Elevated temperature concrete curing - using polypropylene fibres

    OpenAIRE

    Richardson, Alan; Coventry, Kathryn; Morgan, Miles

    2011-01-01

    This paper examines cement hydration when concrete cures at elevated temperatures with and without the addition of Type 1 polypropylene fibres and addresses some of the ambiguities that have arisen from previous research. Paired comparison tests were carried out to compare density, strength, pulse velocity, and absorption using plain and fibre concrete at ambient UK indoor temperatures, compared to concrete at elevated temperatures that would be found in The Middle East. The results ...

  19. Compressive Strength of Fibre Reinforced Concrete

    OpenAIRE

    Jelušič, Matjaž

    2009-01-01

    The thesis features an analysis of the time development of compressive strength of fibre reinforced normal and high strength concrete. Concrete mixtures, taken from the doctoral dissertation of assistant Dr Drago Saje, were used as comparable mixtures to fibre reinforced concrete mixtures with different volume shares of fibres. Two types of steel fibres were used, both featuring the same characteristics but having different lengths (16 and 30 mm), as well as polypropylene fibres. The percenta...

  20. Carbonated concrete blocks for CO2 captation

    OpenAIRE

    Courard, Luc; Parmentier, Véronique; Michel, Frédéric

    2015-01-01

    The CO2 captation process called carbonation, improves specific properties of the concrete during the conversion of carbon dioxide CO2 into calcium carbonate CaCO3. Current environmental concerns motivate the study of carbonation in order to maximize the absorption of carbon dioxide. Moreover, lightweight concrete with bio-based products knows an interesting development in the construction field, especially as thermal insulation panels for walls in buildings. Concrete blocks produced with mis...

  1. Utilization of Electronic Waste Plastic in Concrete

    OpenAIRE

    Vivek S. Damal; Saurabh S. Londhe

    2015-01-01

    In India, bitumen pavements are commonly used for highways. Due to the increasing traffic intensity, distress such as rutting and cracking of pavements are very common in Indian roads. Under varying seasonal temperature, flexible pavements tend to become soft in summer and brittle in winter. Investigations revealed that properties of concrete can be better than bitumen roads. But now a day‟s concrete roads are used commonly because concrete roads have more life span than the bi...

  2. Phase 2 microwave concrete decontamination results

    International Nuclear Information System (INIS)

    The authors report on the results of the second phase of a four-phase program at Oak Ridge National Laboratory to develop a system to decontaminate concrete using microwave energy. The microwave energy is directed at the concrete surface through the use of an optimized wave guide antenna, or applicator, and this energy rapidly heats the free water present in the interstitial spaces of the concrete matrix. The resulting steam pressure causes the surface to burst in much the same way popcorn pops in a home microwave oven. Each steam explosion removes several square centimeters of concrete surface that are collected by a highly integrated wave guide and vacuum system. The authors call this process the microwave concrete decontamination, or MCD, process. In the first phase of the program the principle of microwaves concrete removal concrete surfaces was demonstrated. In these experiments, concrete slabs were placed on a translator and moved beneath a stationary microwave system. The second phase demonstrated the ability to mobilize the technology to remove the surfaces from concrete floors. Area and volume concrete removal rates of 10.4 cm2/s and 4.9 cm3/S, respectively, at 18 GHz were demonstrated. These rates are more than double those obtained in Phase 1 of the program. Deeper contamination can be removed by using a longer residence time under the applicator to create multiple explosions in the same area or by taking multiple passes over previously removed areas. Both techniques have been successfully demonstrated. Small test sections of painted and oil-soaked concrete have also been removed in a single pass. Concrete with embedded metal anchors on the surface has also been removed, although with some increased variability of removal depth. Microwave leakage should not pose any operational hazard to personnel, since the observed leakage was much less than the regulatory standard

  3. Composite structure made of concrete and timber

    OpenAIRE

    Kozjan, Ana

    2009-01-01

    Thesis work is dealing with behavior of composite structure made of concrete and timber. First the scope of the document is introduced following by description of the problem and explaining the purpose and goals. Continuing of the document is presented composite structure concrete-timber. The composite material is described, composite structure is represent, stated are reasons of coupling concrete and timber and the typical connection in composite structure are represented. Thesis describes c...

  4. HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

    OpenAIRE

    O. M. Pshinko; A. V. Krasnyuk; O. V. Hromova

    2015-01-01

    Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings) based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic–viscous–plastic bodies. The system of canon...

  5. Bond between concrete and reinforcing steel

    OpenAIRE

    Dežman, Andraž

    2015-01-01

    This thesis researches bond characteristics between the 12mm steel reinforcing bar and various types of concrete. Standard Eurocode 2 and FIB Model Code 2010 define ultimate bond stress, which acts like shear stress around the reinforcing bar. In correlation with bond, high strength concrete is poorly represented, furthermore, research and information on fibre concrete are lacking. Therefore, a series of pull-out tests, based on standard SIST EN 10080:2005, have been conducted....

  6. Chloride migration in concrete with superabsorbent polymers

    OpenAIRE

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2015-01-01

    Superabsorbent polymers (SAP) can be used as a means for internal curing of concrete. In the present study, the development of transport properties of concrete with SAP is investigated. The chloride migration coefficient according to NT BUILD 492 is used as a measure of this. Twenty concrete mixtures aretested 7, 14, and 28 days after casting. The development of degree of hydration is followed for 20 corresponding paste mixtures.Both when SAP is added with extra water to compensate the SAP wa...

  7. Maintenance and Repair of Concrete Structures

    OpenAIRE

    Bijen, J.M.J.M.

    1989-01-01

    In 1987 and 1988 a series of articles was published in the Dutchjournal "Cement" about maintenance and repair of concrete structures. The series was written to promote the transfer of know-how concerning maintenance and repair of concrete structures. Use has been made of know-how developed in the Netherlands. The Centre for Civil Engineering Research, Codes and Specifications, CUR, is performing an extensive research program regarding repair and protection techniques for concrete. After readi...

  8. Durability of high volume fly ash concrete

    OpenAIRE

    Camões, Aires

    2006-01-01

    It is well known that the concrete industry has to contribute to the sustainability of construction. For this intent it is necessary to reduce the cement content without compromising the durability requirements of the concrete constructions. Therefore, large scale cement replacement in concrete by by products such as fly ash will be extremely beneficial from the overall ecological and environmental point of view. In this context, an experimental research work was carried out focused on the...

  9. Efficient strengthening technique for reinforced concrete slabs

    OpenAIRE

    Bonaldo, Everaldo; Barros, Joaquim A. O.; Lourenço, Paulo B.

    2006-01-01

    A promising strengthening strategy, using carbon fiber reinforced polymer (CFRP) materials, consists in applying CFRP laminate strips into pre-cut slits opened in the concrete cover of the elements to strengthen. This strengthening technique is designated by Near Surface Mounted (NSM) and has been successfully used to increase the flexural and the shear resistance of concrete and masonry structures. The present work describes an efficient strategy, using steel fiber reinforced concrete (SFRC)...

  10. Ductility in lightweight concrete with fiber

    OpenAIRE

    Ahmadyar, Milad

    2011-01-01

    This master thesis presents the influence of different fiber in high-performance lightweight concrete and the ductility capacity of reinforced lightweight concrete beam. Twelve beams with length of 2.2m and reinforcement ratio 0.24 have been tested under 4 point bending, three of them were made by normal density aggregates as references beams. The target concrete compressive strength for all beams were 50MPa. Three different types of fibers such as steel fiber, Polypropylene ma...

  11. Progress of Carbonation in Chloride Contaminated Concretes

    OpenAIRE

    Wang, Yaocheng; Basheer, P.A.M.; Nanukuttan, S; Bai, Y.

    2016-01-01

    Concretes used in marine environment are generally under the cyclic effect of CO2 and chloride ions (Cl-). To date, the influence of carbonation on ingress of chloride ions in concretes has been widely studied; in comparison, study on the influence of Cl- on the progress of carbonation is limited. During the study, concretes were exposed to independent and combined mechanisms of carbonation and chloride ingress regimes. Profiles of apparent pH and chloride concentration were used to indicate ...

  12. Shrinkage of Concrete using Porous Aggregates

    OpenAIRE

    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...

  13. HYDRAULIC CONCRETE COMPOSITION AND PROPERTIES CONTROL SYSTEM

    OpenAIRE

    O. M. Pshinko; KRASNYUK A.V.; O. V. Hromova

    2015-01-01

    Purpose. Scientific work aims at the development and testing of information system to meet the challenges of concrete composition design and control (for railway structures and buildings) based on the physico-analytical method algorithm for hydraulic concrete composition calculation. Methodology. The proposed algorithm of hydraulic concrete composition calculation is based on the physicochemical mechanics and in particular on the rheology of elastic-viscous-plastic bodies. The system of canon...

  14. DECISION MAKING MODELING OF CONCRETE REQUIREMENTS

    OpenAIRE

    Suhartono Irawan; Harry Patmadjaja; Richard Tanara; Fransisca Soeprajogi

    2001-01-01

    This paper presents the results of an experimental evaluation between predicted and practice concrete strength. The scope of the evaluation is the optimisation of the cement content for different concrete grades as a result of bringing the target mean value of tests cubes closer to the required characteristic strength value by reducing the standard deviation. Abstract in Bahasa Indonesia : concrete+mix+design%2C+acceptance+control%2C+optimisation%2C+cement+content.

  15. DECISION MAKING MODELING OF CONCRETE REQUIREMENTS

    Directory of Open Access Journals (Sweden)

    Suhartono Irawan

    2001-01-01

    Full Text Available This paper presents the results of an experimental evaluation between predicted and practice concrete strength. The scope of the evaluation is the optimisation of the cement content for different concrete grades as a result of bringing the target mean value of tests cubes closer to the required characteristic strength value by reducing the standard deviation. Abstract in Bahasa Indonesia : concrete+mix+design%2C+acceptance+control%2C+optimisation%2C+cement+content.

  16. Reliable concrete repair: A critical review

    OpenAIRE

    Lukovic, M.; Ye, G.; Breugel, K. van

    2012-01-01

    This paper highlights the importance of achieving durable and long-term predictable repair of reinforced concrete structures. The performance of concrete repair in past and current engineering practice, including all types of repair and application of different materials, is often unsatisfactory. One of the reasons for this lays in the fact that knowledge regarding bonding mechanism and bond properties at the interface of repair material and concrete substrate is still lacking. This paper int...

  17. Application of diamond tools when decontaminating concrete

    International Nuclear Information System (INIS)

    The utilization of diamond concrete cutting tools offers new potential approaches to the recurring problems of removing contaminated concrete. Innovative techniques can provide exacting removal within a dust-free environment. Present day technology allows remote control operated equipment to perform tasks heretofore considered impossible. Experience gained from years of removing concrete within the construction industry hopefully can contribute new and improved methods to D and D projects

  18. Properties of concrete containing used engine oil

    OpenAIRE

    Nasir Shafiq; Muhd Fadhil Nuruddin; Salmia Beddu

    2011-01-01

    Since last few years cement replacement materials, industrial by-products and agricultural wastes in concrete production are widely used. It imparts positive environmental effect because the waste materials are not released to the environment. It was reported that the leakage of motor oil onto concrete surfaces in old grinding units increased the resistance such concrete to freezing and thawing, it made to understand that the effect is similar to adding an air-entraining chemical admixture to...

  19. Intravital FRET: Probing Cellular and Tissue Function in Vivo

    Directory of Open Access Journals (Sweden)

    Helena Radbruch

    2015-05-01

    Full Text Available The development of intravital Förster Resonance Energy Transfer (FRET is required to probe cellular and tissue function in the natural context: the living organism. Only in this way can biomedicine truly comprehend pathogenesis and develop effective therapeutic strategies. Here we demonstrate and discuss the advantages and pitfalls of two strategies to quantify FRET in vivo—ratiometrically and time-resolved by fluorescence lifetime imaging—and show their concrete application in the context of neuroinflammation in adult mice.

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

    OpenAIRE

    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...

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

    OpenAIRE

    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 ...

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

    OpenAIRE

    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 ...

  3. Experimental Study on Torsion of Steel Fiber Reinforced Concrete Members with Ternary Blended Concrete

    OpenAIRE

    Omer Zaheer Ahmed; Mohd Zaker

    2014-01-01

    The study on the torsional behavior of concrete in which the effect of fiber reinforcement in resisting twisting of concrete beams and performance of concrete with ternary blends. When silica fume is added to fresh concrete it chemically reacts with the CH gel to produces additional CSH gel. The benefit of this reaction is twofold increased compressive strength and chemical resistance. The hydration (mixing with water) of Portland cement produces many compounds, including calcium ...

  4. Influence of added concrete compressive strength on adhesion to an existing concrete substrate

    OpenAIRE

    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 ...

  5. Porous Network Concrete: a bio-inspired building component to make concrete structures self-healing

    OpenAIRE

    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...

  6. CONCRETE DURABILITY Through High Volume Fly ash Concrete (HVFC) A Literature review

    OpenAIRE

    VANITA AGGARWAL; Dr. S.M.GUPTA; Dr.S.N.SACHDE

    2010-01-01

    The application of concrete in construction is as old as the days of Greek and roman civilization. But for numerous easons, the concrete construction industry is not sustainable. It consumes a lot of virgin materials and the principal raw material of concrete i.e. cement is responsible for green house gas emissions causing a threat to environment through global warming. Therefore, the industry has seen various types of concrete in search of a solution to sustainable development. Infrastructur...

  7. Introduction to concrete curing effect on the early performance of modern concrete

    OpenAIRE

    Xiaoxia Zhai

    2015-01-01

    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, whic...

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

    OpenAIRE

    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 ...

  9. Research on working property and early age mechanical property of self-compacting concrete used in steel-concrete structure

    International Nuclear Information System (INIS)

    Background: Self-compacting concrete that has good working property is the prerequisite of steel-concrete structure. The early age mechanical property of self-compacting concrete is the important parameter when design steel-concrete structure. Purpose: This paper attempts to research the working property and early age mechanical property of self-compacting concrete. Methods: Test is used to research the working property and early age mechanical property of self-compacting concrete. Results: Self-compacting concrete that could meet the requirement of steel-concrete structure has been mixed and parameters of early age mechanical property of self-compacting concrete which is necessary for design of steel-concrete structure have been presented. Conclusions: Base on the results, this paper can guide the construction of self-compacting concrete in steel-concrete structure and the design and construction of steel-concrete structure. (author)

  10. Economic analysis of recycling contaminated concrete

    Energy Technology Data Exchange (ETDEWEB)

    Stephen, A.; Ayers, K.W.; Boren, J.K.; Parker, F.L. [Vanderbilt Univ., Nashville, TN (United States)

    1997-02-01

    Decontamination and Decommissioning activities in the DOE complex generate large volumes of radioactively contaminated and uncontaminated concrete. Currently, this concrete is usually decontaminated, the contaminated waste is disposed of in a LLW facility and the decontaminated concrete is placed in C&D landfills. A number of alternatives to this practice are available including recycling of the concrete. Cost estimates for six alternatives were developed using a spreadsheet model. The results of this analysis show that recycling alternatives are at least as economical as current practice.

  11. Applications and Properties of Fibre Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Amit Rai1 ,

    2014-05-01

    Full Text Available In conventional concrete, micro-cracks develop before structure is loaded because of drying shrinkage and other causes of volume change. When the structure is loaded, the micro cracks open up and propagate because of development of such micro-cracks, results in inelastic deformation in concrete. Fibre reinforced concrete (FRC is cementing concrete reinforced mixture with more or less randomly distributed small fibres. In the FRC, a numbers of small fibres are dispersed and distributed randomly in the concrete at the time of mixing, and thus improve concrete properties in all directions. The fibers help to transfer load to the internal micro cracks. FRC is cement based composite material that has been developed in recent years. It has been successfully used in construction with its excellent flexural-tensile strength, resistance to spitting, impact resistance and excellent permeability and frost resistance. It is an effective way to increase toughness, shock resistance and resistance to plastic shrinkage cracking of the mortar. These fibers have many benefits. Steel fibers can improve the structural strength to reduce in the heavy steel reinforcement requirement. Freeze thaw resistance of the concrete is improved. Durability of the concrete is improved to reduce in the crack widths. Polypropylene and Nylon fibers are used to improve the impact resistance. Many developments have been made in the fiber reinforced concrete.

  12. Use of SCC in Prefabricated Concrete Elements

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm; Lauritsen, Ib

    2004-01-01

    This paper presents observations made on the use of self-compacting concrete for pre-cast elements at Byggebjerg Beton A/S during the last 3 years. The elements include L- and sandwich elements and are mainly produced for agriculture purposes. In general, the flow properties and air content are...... concrete to achieve a good surface quality with a limited number of blowholes. For horizontal castings it is important to keep the concrete flowing to avoid casting joints. Blocking is avoided by using the right type of spacers and a maximum size aggregate of 8mm. However, if the concrete has to flow over...

  13. STRUCTURAL AND THERMOPHYSICAL PROPERTIES OF HARDENING CONCRETE

    Directory of Open Access Journals (Sweden)

    L. Krasulina

    2012-01-01

    Full Text Available Structural and thermophysical properties of thermally treated concrete have been studied in the paper. The paper demonstrates regularities of changes in structural and thermophysical properties of concrete during heat treatment process. It is established that stabilization of coefficient values for heat- and temperature conductivity of concrete corresponds to completion of the process pertaining to intensive formation of the material pore structure and indicates the possibility of transition from the stage of isothermal extraction to the stage of temperature decrease. The obtained results are confirmed by studies of strength growth kinetics of concrete samples.

  14. Cement and Concrete Nanoscience and Nanotechnology

    Directory of Open Access Journals (Sweden)

    Taijiro Sato

    2010-02-01

    Full Text Available Concrete science is a multidisciplinary area of research where nanotechnology potentially offers the opportunity to enhance the understanding of concrete behavior, to engineer its properties and to lower production and ecological cost of construction materials. Recent work at the National Research Council Canada in the area of concrete materials research has shown the potential of improving concrete properties by modifying the structure of cement hydrates, addition of nanoparticles and nanotubes and controlling the delivery of admixtures. This article will focus on a review of these innovative achievements.

  15. Concrete under severe conditions. Environment and loading

    International Nuclear Information System (INIS)

    The objective of the CONSEC Conferences is to focus on concrete infrastructures, either subjected to severe environment or severe loading, or any combination of severe conditions. Experience from the performance of existing concrete structures, and especially under severe environmental conditions, severe accidental loading or extended lifespan, has demonstrated the need for better integration of structural and durability design, new design concepts including reliability-based durability design, performance-based material requirements, structural robustness, and an improved basis for documentation of obtained construction quality and durability properties during concrete construction. An improved basis for operation and preventive maintenance of concrete structures including repairs and retrofitting is also very important. Premature corrosion of reinforcing steel, inadequate structural design for seismic or blast loading, are examples of reduced service life of concrete structures that not only represent technical and economical problems, but also a huge waste of natural resources and hence also, an environmental and ecological problem. Experience of structures effectively submitted to severe conditions represents a unique benchmark for quantifying the actual safety and durability margin of concrete structures. In fact for several reasons, most concrete design codes, job specifications and other requirements for concrete structures have frequently shown to yield insufficient and unsatisfactory results and ability to solve the above problems, as well as issues raised by specific very long-term or very severe requirements for nuclear and industrial waste management, or civil works of strategic relevance. Recently available high to ultra-high performance concrete may find rational and valuable application in such cases. It is very important, therefore, to bring people with different professional backgrounds together to exchange experience and develop multi

  16. Radiation damage in reactor cavity concrete

    International Nuclear Information System (INIS)

    License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has established a renewed focus on long-term aging of nuclear generating stations materials, and recently, on concrete (large irreplaceable sections of most nuclear generating stations include concrete). The Electric Power Research Institute (EPRI) and Oak Ridge National Laboratory (ORNL) have established a research plan to investigate the aging and degradation processes associated with concrete used in NPPs. This paper outlines the research program including: 1) defining the upper bound of the neutron and gamma dose levels expected in the biological shield concrete for extended operation (80 years of operation and beyond), 2) determining the effects of neutron and gamma irradiation as well as extended time at temperature on concrete, 3) evaluating opportunities to irradiate prototypical concrete under accelerated neutron and gamma dose levels to establish a conservative bound and share data obtained from different flux, temperature, and fluence levels, 4) evaluating opportunities to harvest and test irradiated concrete from international NPPs, 5) developing cooperative test programs to improve confidence in the results from the various concretes and research reactors, 6) furthering the understanding of the effects of radiation on concrete and 7) establishing an international collaborative research and information exchange effort to leverage capabilities and knowledge

  17. Properties of Fiber Reinforced Polymer Concrete

    Directory of Open Access Journals (Sweden)

    Marinela Bărbuţă

    2008-01-01

    Full Text Available Polymer concrete is a composite material realized with resin and aggregates. In the present study the epoxy resin was used for binding the aggregates. In the composition were introduced near the fly ash, used as filler, the cellulose fibers. The mechanical characteristics such as compressive strength, flexural strength and split tensile strength of polymer concrete with fibers were investigated. The fiber percentage was constant, the epoxy resin and the filler dosages were varied. The cellulose fiber had not improved the mechanical characteristics of the polymer concrete in comparison to that of polymer concrete without cellulose fibers.

  18. Equipment for removal of contaminated concrete surfaces

    International Nuclear Information System (INIS)

    The Pacific Northwest Laboratory is investigating and developing equipment that will rapidly and economically remove contaminated concrete surfaces while producing a minimal amount of contaminated rubble. Evaluation of various methods for removing concrete surfaces shows that many of the techniques presently used for decontamination require excessive manpower, time, or energy, or they remove more material than is necessary to clean the surface. Excess material removal increases the quantity of waste that must be handled under controlled conditions. Three unique decontamination methods are presented here: the water cannon, the concrete spaller, and the high-pressure water jet. The water cannon fires a small, high-velocity jet of fluid to spall the concrete surface. The concrete spaller ships away the concrete by exerting radial pressure against the sides of a shallow cylindrical hole drilled into the concrete surface. The high-pressure water jet is a 50,000-psi spray that blasts away the concrete surface. Each method includes means for containing airborne contamination. Results of tests show that these techniques can rapidly and economically remove surfaces, leaving minimal rubble for controlled disposal. Also presented are cost comparisons between the water cannon and the concrete spaller

  19. Proceedings of the concrete decontamination workshop

    International Nuclear Information System (INIS)

    Fourteen papers were presented. These papers describe concrete surface removal methods and equipment, as well as experiences in decontaminating and removing both power and experimental nuclear reactors

  20. Proceedings of the concrete decontamination workshop

    Energy Technology Data Exchange (ETDEWEB)

    Halter, J.M.; Sullivan, R.G.; Currier, A.J.

    1980-05-28

    Fourteen papers were presented. These papers describe concrete surface removal methods and equipment, as well as experiences in decontaminating and removing both power and experimental nuclear reactors.

  1. Experimental needs of high temperature concrete

    International Nuclear Information System (INIS)

    The needs of experimental data on concrete structures under high temperature, ranging up to about 3700C for operating reactor conditions and to about 9000C and beyond for hypothetical accident conditions, are described. This information is required to supplement analytical methods which are being implemented into the finite element code TEMP-STRESS to treat reinforced concrete structures. Recommended research ranges from material properties of reinforced/prestressed concrete, direct testing of analytical models used in the computer codes, to investigations of certain aspects of concrete behavior, the phenomenology of which is not well understood. 10 refs

  2. Concretes characterization for spent radioactive sources

    International Nuclear Information System (INIS)

    The present work includes the preparation and characterization of the concrete used as conditioning matrix of spent radioactive sources in the Treatment Plant of Radioactive Wastes of the Instituto Nacional de Investigaciones Nucleares (ININ). The concrete tests tubes were subjected to resistance assays to the compression, leaching, resistance to the radiation and porosity, and later on characterized by means of X rays diffraction, scanning electron microscopy and infrared spectrometry, with the purpose of evaluating if this concrete accredits the established tests by the NOM-019-Nucl-1995. The results show that the concrete use in the Treatment Plant fulfills the requirements established by the NOM-019-Nucl-1995. (author)

  3. Model techniques for testing heated concrete structures

    International Nuclear Information System (INIS)

    Experimental techniques are described which may be used in the laboratory to measure strains of model concrete structures representing to scale actual structures of any shape or geometry, operating at elevated temperatures, for which time-dependent creep and shrinkage strains are dominant. These strains could be used to assess the distribution of stress in the scaled structure and hence to predict the actual behaviour of concrete structures used in nuclear power stations. Similar techniques have been employed in an investigation to measure elastic, thermal, creep and shrinkage strains in heated concrete models representing to scale parts of prestressed concrete pressure vessels for nuclear reactors. (author)

  4. Innovative techniques for removing concrete surfaces

    International Nuclear Information System (INIS)

    This report centers on the use of heat to decompose contaminated concrete to facilitate its removal. It discusses the use of electrical resistance heating and induction heating to cause differential expansion between the reinforcing steel and the concrete in order to spall the concrete. It introduces the concept of using induction heating to both decompose and spall steel impregnated concrete, acknowledging the work of Charles H. Henager in this field. The techniques are offered as theoretical and untested possibilities. Their practical application depends upon the effectiveness of alternatives and upon further development of these concepts

  5. Failover in cellular automata

    CERN Document Server

    Kumar, Shailesh

    2010-01-01

    A cellular automata (CA) configuration is constructed that exhibits emergent failover. The configuration is based on standard Game of Life rules. Gliders and glider-guns form the core messaging structure in the configuration. The blinker is represented as the basic computational unit, and it is shown how it can be recreated in case of a failure. Stateless failover using primary-backup mechanism is demonstrated. The details of the CA components used in the configuration and its working are described, and a simulation of the complete configuration is also presented.

  6. Cellular-scale hydrodynamics

    DEFF Research Database (Denmark)

    Abkarian, Manouk; Faivre, Magalie; Horton, Renita; Smistrup, Kristian; Best-Popescu, Catherine A; Stone, Howard A.

    2008-01-01

    Microfluidic tools are providing many new insights into the chemical, physical and physicochemical responses of cells. Both suspension-level and single-cell measurements have been studied. We review our studies of these kinds of problems for red blood cells with particular focus on the shapes of ...... mechanical effects on suspended cells can be studied systematically in small devices, and how these features can be exploited to develop methods for characterizing physicochemical responses and possibly for the diagnosis of cellular-scale changes to environmental factors....

  7. Cellular mechanics and motility

    Science.gov (United States)

    Hénon, Sylvie; Sykes, Cécile

    2015-10-01

    The term motility defines the movement of a living organism. One widely known example is the motility of sperm cells, or the one of flagellar bacteria. The propulsive element of such organisms is a cilium(or flagellum) that beats. Although cells in our tissues do not have a flagellum in general, they are still able to move, as we will discover in this chapter. In fact, in both cases of movement, with or without a flagellum, cell motility is due to a dynamic re-arrangement of polymers inside the cell. Let us first have a closer look at the propulsion mechanism in the case of a flagellum or a cilium, which is the best known, but also the simplest, and which will help us to define the hydrodynamic general conditions of cell movement. A flagellum is sustained by cellular polymers arranged in semi-flexible bundles and flagellar beating generates cell displacement. These polymers or filaments are part of the cellular skeleton, or "cytoskeleton", which is, in this case, external to the cellular main body of the organism. In fact, bacteria move in a hydrodynamic regime in which viscosity dominates over inertia. The system is thus in a hydrodynamic regime of low Reynolds number (Box 5.1), which is nearly exclusively the case in all cell movements. Bacteria and their propulsion mode by flagella beating are our unicellular ancestors 3.5 billion years ago. Since then, we have evolved to form pluricellular organisms. However, to keep the ability of displacement, to heal our wounds for example, our cells lost their flagellum, since it was not optimal in a dense cell environment: cells are too close to each other to leave enough space for the flagella to accomplish propulsion. The cytoskeleton thus developed inside the cell body to ensure cell shape changes and movement, and also mechanical strength within a tissue. The cytoskeleton of our cells, like the polymers or filaments that sustain the flagellum, is also composed of semi-flexible filaments arranged in bundles, and also in

  8. Radiolabelled Cellular Blood Elements

    International Nuclear Information System (INIS)

    This volume contains the abstracts of the 5th International Symposion on Radiolabelling of Cellular Blood Elements to be held in Vienna, Austria, September 10-14, 1989. The Meeting is the fifth in a series of meetings designed to discuss the basics and clinical application of radiolabelling techniques. In these days, beside the search for new labelling agents and extending the knowledge in clinical use, the use of monoclonal antibodies is a big new challenge. All reviewed contributions that have been accepted for presentation are contained in this volume. (authors) 58 of them are of INIS scope

  9. Comparison of Performance of Standard Concrete And Fibre Reinforced Standard Concrete Exposed To Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    K.Srinivasa Rao

    2013-01-01

    Full Text Available Concrete elements exposed to fire undergo temperature gradients and as a result, undergo physical changes or spalling which leads to expose steel reinforcement. This causes distress in concrete structures. The performance of concrete can be improved with the addition of steel fibres to concrete especially when it is exposed to heat. Therefore, this study has been carried out to generate experimental data on standard concrete ofgrade M45 and Fiber Reinforced Standard Concrete exposed to elevated temperatures. For each type of concrete six sets of cubes, cylinders, and beams have been cast. Each set contains 5specimens. A total of thirty cubes, thirty cylinders, and thirty beams of Standard Concrete and Fiber Reinforced Standard Concrete have been cast, out of which 5 sets of standard concrete and fiber reinforced standard concrete are exposed to elevated temperatures of 500C, 1000C, 1500C, 2000C and 2500C for 3 hours and the sixth set is tested at room temperature as control concrete. These specimens have been tested for compressive strength, split tensile strength, and flexural strength in hot condition immediately after taking out from oven. The results are analyzed and final conclusions are drawn.

  10. Modelling reinforcement corrosion in concrete

    DEFF Research Database (Denmark)

    Michel, Alexander; Geiker, Mette Rica; Stang, Henrik;

    2012-01-01

    reached causing the formation of anodic and cathodic regions along the reinforcement. Critical chloride thresholds, randomly distributed along the reinforcement sur-face, link the initiation and propagation phase of reinforcement corrosion. To demonstrate the potential use of the developed model, a......A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold is...

  11. Construction of concrete hot cells

    International Nuclear Information System (INIS)

    1. Construction of concrete hot cells; 1.1 Fundamentals; 1.2 Cell sizes; 1.3 Cell categories; 1.4 Work place/operating place and cell ergonomics; 1.5 Cell instrumentation. 2. Shielding; 2.1 louerete walls; 2.2 Big access holes. 3. Standard equipment; 3.1 Manipulators; 3.2 Radiation protection windows; 3.3 Safety boxes; 3.4 Equipment transfer airlocks; 3.5 Duets; 3.6 Working tables; 3.7 Illumination; 3.8 Ventilation system.

  12. Innovations in nuclear concrete constructions

    International Nuclear Information System (INIS)

    The technical requirements and scope of concrete work on nuclear projects present significant engineering and construction challenges. These demands represent the extremes in many areas of construction operations. In meeting these challenges, engineering and construction forces have developed several innovations which can be beneficially applied to other types of construction. Innovative approaches in the general categories of engineering scope, construction input to engineering, work planning, special methods and techniques, and satisfaction of quality assurance requirements are given in this paper. The transfer of this technology to other segments of the construction industry will improve overall performance by avoiding the problem areas encountered on nuclear projects

  13. Microcracking and durability of high strength concretes

    International Nuclear Information System (INIS)

    Durability of 28 days compressive strength concrete of 20 to 120 MPa has been studied. The ability of concrete to transport aggressive agents has been determined for four properties: the air permeability, the chloride diffusivity, the water absorption and the carbonation. A chloride migration test for high and very high strength concrete (HSC and VHSC) has been built. The relationship between transport properties and the compressive strength after one and 28 days of humid curing has always the same shape: transport decreases when strength increases. However, transport properties often vary in the ordinary concrete field. Beyond, the domain is much more limited. The relationship between transport properties and strength valid for ordinary concrete can not be simply extrapolated for HSC and VHSC. To determine the part of microcracking of HSC and VHSC, concrete behaviour stored in two mediums has been studied: the ones shaming the storing condition of concrete in auto-desiccation, the others reproducing the storing conditions of concrete in desiccation. Auto-desiccation (measuring relative humidity at balance) and desiccation (measuring mass losses) have been showed. Microcracks and shrinkage strains have been measured. It has been showed that auto-desiccation microcracks proving in HSC or VHSC don't question the durability. Microcracks, as for permeability, do not develop between 28 days and one year. On the contrary, desiccation microcracks observed in HSC and VHSC, increase with transport properties between 28 days and 1.5 year. Thus, a bulk concrete is always more durable than a cover concrete. At last, the good influence of increase of curing of 1 to 28 days on the transport of all concretes has been emphasized. (author)

  14. Lightened plaster: alternative solutions to cellular solids addition

    Directory of Open Access Journals (Sweden)

    Del Río, M.

    2004-09-01

    Full Text Available The following paper pretends to analyze different processes in order to lightweighters gypsum as an alternative way at the cellular fillers addition, in order to establish the most suitable ones for the manufacture of plasterboard. Outstanding the process which uses foamings addition to lighten gypsum uses nowdays only to manufacture cellular concrete.

    En este artículo se presenta el análisis de diferentes procedimientos para aligerar la escayola, como alternativas a la adición de sólidos celulares, determinando los más adecuados para la realización de prefabricados. Dentro de estos procedimientos cabe destacar la adición de espumantes, hasta ahora sólo utilizados para la fabricación de hormigones celulares.

  15. Fibrous Calcareous Concretions in the Capsules of Human Pineal Glands

    OpenAIRE

    Kodaka Tetsuo; Mori Ryoichi; Ezure Hiromitsu; Ito Junji; Otsuka Naruhito

    2013-01-01

    We examined calcareous concretions in the capsule of 15 human pineal glands containing a large amount of the concretions in the matrix. The capsule concretions, brown to blackish-brown in color and/or translucent, were smaller than the matrix concretions, which were yellowish-white. The matrix concretions showed the typical mulberry-shaped overall appearance with scallop-shaped concentric laminations of non-fibrous structures, but the capsule concretions, which also contained Ca and P, showed...

  16. US Patent: Composite concrete article and method of manufacture thereof

    OpenAIRE

    Morrow, Ruth; Belford, Patricia

    2014-01-01

    A method of manufacturing a composite concrete article comprising affixing at least one layer of textile to a base layer and incorporating the base layer into a body of wet uncured concrete such that the base layer becomes embedded in the concrete, whereby at least a portion of the at least one textile layer defines at least a portion of a surface of the cured concrete article with the base layer embedded within the concrete to anchor the textile layer to the concrete.

  17. Study on Micro-Structure and Durability of Fiber Concrete

    OpenAIRE

    Huijun Wu; Jing Zhao; Zhongchang Wang

    2013-01-01

    In this study, we compare micro-structure characteristics of alkali-resistant glass fiber reinforced concrete, polypropylene fiber reinforced concrete, basalt fiber reinforced concrete and common concrete. Moreover, they were tested and analyzed micro-structure characteristics of fiber reinforced concretes by mercury injection, mainly analyzed the size of pore distribution, studied the influence on improving pore structure. In addition, the internal structure of fiber reinforced concrete was ...

  18. Integrated cellular systems

    Science.gov (United States)

    Harper, Jason C.

    The generation of new three-dimensional (3D) matrices that enable integration of biomolecular components and whole cells into device architectures, without adversely altering their morphology or activity, continues to be an expanding and challenging field of research. This research is driven by the promise that encapsulated biomolecules and cells can significantly impact areas as diverse as biocatalysis, controlled delivery of therapeutics, environmental and industrial process monitoring, early warning of warfare agents, bioelectronics, photonics, smart prosthetics, advanced physiological sensors, portable medical diagnostic devices, and tissue/organ replacement. This work focuses on the development of a fundamental understanding of the biochemical and nanomaterial mechanisms that govern the cell directed assembly and integration process. It was shown that this integration process relies on the ability of cells to actively develop a pH gradient in response to evaporation induced osmotic stress, which catalyzes silica condensation within a thin 3D volume surrounding the cells, creating a functional bio/nano interface. The mechanism responsible for introducing functional foreign membrane-bound proteins via proteoliposome addition to the silica-lipid-cell matrix was also determined. Utilizing this new understanding, 3D cellular immobilization capabilities were extended using sol-gel matrices endowed with glycerol, trehalose, and media components. The effects of these additives, and the metabolic phase of encapsulated S. cerivisiase cells, on long-term viability and the rate of inducible gene expression was studied. This enabled the entrapment of cells within a novel microfluidic platform capable of simultaneous colorimetric, fluorescent, and electrochemical detection of a single analyte, significantly improving confidence in the biosensor output. As a complementary approach, multiphoton protein lithography was utilized to engineer 3D protein matrices in which to

  19. Investigation of modified asphalt concrete

    Science.gov (United States)

    Zimich, Vita

    2016-01-01

    Currently the problem of improving the asphalt quality is very urgent. It is used primarily as topcoats exposed to the greatest relative to the other layers of the road, dynamic load - impact and shear. The number of cars on the road, the speed of their movement, as well as the traffic intensity increase day by day. We have to upgrade motor roads, which entails a huge cost. World experience shows that the issue is urgent not only in Russia, but also in many countries in Europe, USA and Asia. Thus, the subject of research is the resistance of asphalt concrete to water and its influence on the strength of the material at different temperatures, and resistance of pavement to deformation. It is appropriate to search for new modifiers for asphaltic binder and mineral additives for asphalt mix to form in complex the skeleton of the future asphalt concrete, resistant to atmospheric condensation, soil characteristics of the road construction area, as well as the growing road transport load. The important task of the work is searching special modifying additives for bitumen binder and asphalt mixture as a whole, which will improve the quality of highways, increasing the period between repairs. The methods described in the normative-technical documentation were used for the research. The conducted research allowed reducing the frequency of road maintenance for 7 years, increasing it from 17 to 25 years.

  20. Nanomodified magnesian schungite protective concrete

    Directory of Open Access Journals (Sweden)

    A.S. Ryzhov

    2010-03-01

    Full Text Available Currently, there is increasing demand for building materials with low permeability to the radioactive gas radon and materials that have protective properties against radiation exposure and non-ionizing radiation. Formulations have been developed and now special building flooring and plaster radiation protective mixtures are commercially available. With the acceleration the pace of development of nuclear energy safe utilization of liquid and solid radioactive waste is a vital task for the survival of humanity.With the use of innovative magnesian barite and magnesian schungite composites opportunities to solidify LRW and solid radioactive waste monolithing are expanded. Magnesium-schungite nanostructured concrete exceed heavy concrete on Portland cement by gamma radiation and strength characteristics reducing multiplicity. Formulations are protected by a patent for an invention.The paper shows a clear advantage of magnesia cement (compared with Portland cement in terms of specific mass energy parameters Em and Wm. The data demonstrates that the magnesia cement is characterized by higher parameters of maximum frequency of oscillation of the atoms ?m, which, apparently, is the key to explaining the increased protection (shielding properties of materials based on magnesia cement mixed with shungite of gamma radiation and exposure to radiofrequency electromagnetic radiation the range.Magnesium-schungite radiation-shielding materials are approved by Rospotrebnadzor for use for collective protection to reduce the income of radon in indoor air, gamma and x-ray production, residential, public and administrative buildings, as well as in food, pharmaceutical, medical and child care.

  1. Concrete decontamination and demolition methods

    International Nuclear Information System (INIS)

    The US Department of Energy (DOE), Division of Environmental Control Technology, requested Nuclear Energy Services to prepare a handbook for the decontamination and decommissioning (D and D) of DOE-owned and commercially-owned radioactive facilities. the objective of the handbook is to provide the nuclear industry with guidance on the state-of-the-art methods and equipment available for decommissioning and to provide the means to estimate decommissioning costs and environmental impact. The methods available for concrete decontamination and demolition are summarized to provide an overview of some of the state-of-the-art techniques to be discussed at this workshop. The pertinent information on each method will include the selection factors such as the rate of performance in terms of concrete removal per unit time (cubic yards per day), manpower required by craft, unit cost (dollars per cubic yard) and the advantages and disadvantages. The methods included in this overview are those that have been routinely used in nuclear and nonnuclear applications or demonstrated in field tests. These methods include controlled blasting, wrecking ball or slab, backhoe mounted ram, flame torch, thermic lance, rock splitter, demolition compound, sawing, core stitch drilling, explosive cutting, paving breaker and power chisel, drill and spall, scarifying, water cannon and grinding

  2. Radionuclide Retention in Concrete Wasteforms

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Dawn M.; Jansik, Danielle P.; Golovich, Elizabeth C.; Cordova, Elsa A.

    2012-09-24

    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of LLW and MLLW, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

  3. Transport of gases through concrete

    International Nuclear Information System (INIS)

    Gases will be generated within a radioactive waste repository. The magnitude of the gas pressure caused by the build-up of such gases will depend on the relative rates of gas generation and release from the repository. An increase in the gas pressure has the potential to affect the integrity of the repository structure. This structure will be mainly comprised of materials based on hydraulic cements (concretes and grouts) which exhibit some degree of permeability. It is essential, therefore, to understand the migration of gases through structures composed of such materials so that any deleterious effects can be avoided in the design of the repository. The bulk of the gas produced will be hydrogen, from the anaerobic corrosion of steels. The contribution from methane produced by the degradation of organic components in the waste may also be significant. The object of this work is to quantify the gas migration rate in several different types of cementitious material as a function of both gas pressure and the degree of water saturation and to establish whether the pressures likely to be achieved in a repository can cause the expected transition to bulk flow migration in water-saturated concrete. This report details progress made during the first year of the research programme. (author)

  4. RADON GENERATION AND TRANSPORT THROUGH CONCRETE FOUNDATIONS

    Science.gov (United States)

    The report gives results of an examination of radon generation and transport through Florida residential concretes for their contribution to indoor radon concentrations. Radium concentrations in the 11 concretes tested were all <2.5 pCi/g and radon emanation coefficients were all...

  5. Re-Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper two aspects of re-assessment of the reliability of concrete bridges are discussed namely modelling of the corrosion of reinforcement and updating of uncertain variables. The main reason for deterioration of concrete bridges is corrosion of the reinforcement. Therefore, modelling of...

  6. Elevated temperature effects on concrete properties

    International Nuclear Information System (INIS)

    The design of facilities to process or store radioactive wastes presents many challenging engineering problems. These facilities must not only provide safe storage of radioactive wastes but must also be able to maintain confinement of these materials during and after natural phenomena events. Heat generated by the radioactive decay of the wastes will cause the temperature of the concrete containment structure to increase to a magnitude higher than that found in conventional structures. These elevated temperatures will cause strenght related concrete properties to degrade over time. For concrete temperatures less than 150 degrees F no reduction in strength is taken and the provisions of ACI 349 apply. ACI 349 states that higher temperatures are allowed if tests are provided to evaluate the reduction in concrete strength properties. Methods proposed in a report, 'Modeling of Time-Variant Concrete Properties at Elevated Temperatures', by Pacific Northwest Laboratories can be used to evaluate the effects of elevated temperatures on concrete properties. Using these modified concrete properties the capacity of a concrete structure, subjected to elevated temperatures, to resist natural phenomena hazards can be determined

  7. Properties of concrete containing used engine oil

    Directory of Open Access Journals (Sweden)

    Nasir Shafiq

    2011-07-01

    Full Text Available Since last few years cement replacement materials, industrial by-products and agricultural wastes in concrete production are widely used. It imparts positive environmental effect because the waste materials are not released to the environment. It was reported that the leakage of motor oil onto concrete surfaces in old grinding units increased the resistance such concrete to freezing and thawing, it made to understand that the effect is similar to adding an air-entraining chemical admixture to the concrete. However, the hypothesis is not backed by significant research study and not reported in the available literature. This paper presents results of the experimental study conducted to investigate the effects of used engine oil on properties of fresh and hardened concrete.  With the addition of used engine oil, concrete slump was increased by 18% to 38% and air content by 26% to 58% as compare to the slump of control concrete. Porosity and oxygen permeability of concrete containing used engine oil was also reduced and the compressive strength was obtained approximately same as that of the control mix

  8. Elevated temperature effects on concrete properties

    International Nuclear Information System (INIS)

    The design of facilities to process or store radioactive wastes presents many challenging engineering problems. Such facilities must not only provide for safe storage of radioactive wastes but they must also be able to maintain confinement of these materials during and after natural phenomena events. Heat generated by the radioactive decay of the wastes will cause the temperature of the concrete containment structure to increase to a magnitude higher than that found in conventional structures. These elevated temperatures will cause strength-related concrete properties to degrade over time. For concrete temperatures less than 150 degree F, no reduction in strength is taken and the provisions of ACI 349, which states that higher temperatures are allowed if tests are provided to evaluate the reduction in concrete strength properties, apply. Methods proposed in a Pacific Northwest Laboratory (PNL) report, Modeling of Time-Variant Concrete Properties at Elevated Temperatures, can be used to evaluate the effects of elevated temperatures on concrete properties. Using these modified concrete properties the capacity of a concrete structure, subjected to elevated temperatures, to resist natural phenomena hazards can be determined

  9. Analyses of Concrete Structures Exposed to Fire

    DEFF Research Database (Denmark)

    Hertz, Kristian

    The text book contains the data and methods necessary for fire safety design of concrete constructions. The methods relate to standard fire as well as to any time of any other fire course.Material data are presented for concretes exposed to fire, and calculation methods are given for the ultimate...

  10. Present Stage of Gelivity Resistant Concrete Features

    Directory of Open Access Journals (Sweden)

    Bogdan Rujanu

    2008-01-01

    Full Text Available The characteristics of the concrete gelivity by imposing strictly conditions to the composition are studied. We observed the new formed structure so as components from cement stone, vulnerable at freeze thaw, to be lower as percentage. The resulted concrete structures will have the main characteristic of reduced cement consumption, high exigencies of freeze thaw durability and low costs.

  11. Form Filling with Self-Compacting Concrete

    DEFF Research Database (Denmark)

    Thrane, Lars Nyholm

    2002-01-01

    This paper describes a newly started Ph.D. project with the aim of simulating the form filling ability of Self-Compacting Concrete (SCC) taking into account the form geometry, reinforcement configuration, casting technique, and the rheological properties of the concrete. Comparative studies of the...

  12. Durability of hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.; Borsje, H.

    1998-01-01

    The subject of this study was the performance of hydrophobic treatment to protect concrete against chloride penetration from de-icing salts. Hydrophobic treatment makes a concrete surface absorb less water and less chloride. Several types of tests were carried out to study the performance of hydroph

  13. Durability of hydrophobic treatment of concrete

    NARCIS (Netherlands)

    Vries, J. de; Polder, R.B.; Borsje, H.

    1998-01-01

    The subject of this study was the performance of hydrophobic treatment to protect concrete against chloride penetration from de-icing salts. Hydrophobic treatment makes a concrete surface absorb less water and less chloride. Test methods and requirements for commercial products were established. In

  14. PULSED LASER ABLATION OF CEMENT AND CONCRETE

    Science.gov (United States)

    Laser ablation was investigated as a means of removing radioactive contaminants from the surface and near-surface regions of concrete from nuclear facilities. We present the results of ablation tests on cement and concrete samples using a pulsed Nd:YAG laser with fiber optic beam...

  15. Fatigue Performance of Fiber Reinforced Concrete

    DEFF Research Database (Denmark)

    Jun, Zhang; Stang, Henrik

    1996-01-01

    The objective of the present study is to obtain basic data of fibre reinforced concrete under fatigue load and to set up a theoretical model based on micromechanics. In this study, the bridging stress in fiber reinforced concrete under cyclic tensile load was investigted in details. The damage...

  16. Review of constructive models for concrete

    International Nuclear Information System (INIS)

    This report has been prepared for the Commission of the European Communities, Joint Research Centre, ISPRA. The report reviews the constitutive models for concrete and is a part of a survey of the status of the analytical capabilities for predicting the structural response of NPP concrete containment buildings to severe loading conditions

  17. Polymer concrete cell applications in zinc electrowinning

    International Nuclear Information System (INIS)

    The use of polymer concrete cells in zinc electrowinning plants is discussed and the properties of these cells are described. These include, improved corrosion resistance, modularization, maintenance reduction and integrated designs and attachments for bus bars and walkways and for solution handling. Use of UNICELL polymer concrete cells in different cell houses is reviewed. (author)

  18. Concrete corrosion associated with Thiobacillus (SP - Brazil)

    International Nuclear Information System (INIS)

    The presence of Thiobacillus, heterotrophic bacteria and fungi is investigated in concrete samples from a deteriorated water tank. A sample of the soil which was in contact with the concrete was also evaluated. The thiobacillus isolated were submitted to a growth test. (M.A.C.)

  19. Self-compacting fibre-reinforced concrete

    NARCIS (Netherlands)

    Grunewald, S.; Walraven, J.C.

    2001-01-01

    The project 'self-compacting fibre-reinforced concrete (SCFRC)' is part of the Dutch STW/PPM program - 'cement-bonded materials' - DCT.4010. Subproject III to which the project ,SCFRC' belongs deals with the development of new high performance concretes. The project 'SCFRC' aims at investigating the

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

    Directory of Open Access Journals (Sweden)

    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

  1. A Study on the Cover Failure in Concrete Structure Following Concrete Deterioration

    International Nuclear Information System (INIS)

    The RC (Reinforced Concrete) structures in the spent fuel dry storage is required structural integrity for a long period of the service life time. A study on the concrete cracking behavior by stress on concrete is necessary for life time estimation of structures because concrete cracking can reduce the radiation shielding performance and deteriorate the durability of spent fuel dry storage. The purpose of this study is to analyze the relationship between the range of the steel expansion and the crack creation and propagation using the ABAQUS tool. Parameters used in this study were concrete strength, concrete cover depth and the steel diameter. The value of steel radius to volume expansion was applied to suppose the expansion of reinforcing bar under the load condition. As a result of this case study, it is confirmed that the critical steel expansion which can initiate cracking is proportional to tensile strength. And primary factors which effect crack creation of concrete cover are in order of concrete strength, cover thickness and steel diameter. If concrete strength is lowered about its 30%, the rate of surface crack occurrence accelerates 15 times maximally. The critical expansion value of steel increased as the increment of concrete cover depth. The surface cracking of concrete cover was created at the value of steel expansion, ranging from 0.019 to 0.051 mm under the cover depth 50 mm. (authors)

  2. Multiuser Cellular Network

    CERN Document Server

    Bao, Yi; Chen, Ming

    2011-01-01

    Modern radio communication is faced with a problem about how to distribute restricted frequency to users in a certain space. Since our task is to minimize the number of repeaters, a natural idea is enlarging coverage area. However, coverage has restrictions. First, service area has to be divided economically as repeater's coverage is limited. In this paper, our fundamental method is to adopt seamless cellular network division. Second, underlying physics content in frequency distribution problem is interference between two close frequencies. Consequently, we choose a proper frequency width of 0.1MHz and a relevantly reliable setting to apply one frequency several times. We make a few general assumptions to simplify real situation. For instance, immobile users yield to homogenous distribution; repeaters can receive and transmit information in any given frequency in duplex operation; coverage is mainly decided by antenna height. Two models are built up to solve 1000 users and 10000 users situations respectively....

  3. Modeling and cellular studies

    International Nuclear Information System (INIS)

    Testing the applicability of mathematical models with carefully designed experiments is a powerful tool in the investigations of the effects of ionizing radiation on cells. The modeling and cellular studies complement each other, for modeling provides guidance for designing critical experiments which must provide definitive results, while the experiments themselves provide new input to the model. Based on previous experimental results the model for the accumulation of damage in Chlamydomonas reinhardi has been extended to include various multiple two-event combinations. Split dose survival experiments have shown that models tested to date predict most but not all the observed behavior. Stationary-phase mammalian cells, required for tests of other aspects of the model, have been shown to be at different points in the cell cycle depending on how they were forced to stop proliferating. These cultures also demonstrate different capacities for repair of sublethal radiation damage

  4. Engineering Cellular Metabolism

    DEFF Research Database (Denmark)

    Nielsen, Jens; Keasling, Jay

    2016-01-01

    Metabolic engineering is the science of rewiring the metabolism of cells to enhance production of native metabolites or to endow cells with the ability to produce new products. The potential applications of such efforts are wide ranging, including the generation of fuels, chemicals, foods, feeds......, and pharmaceuticals. However, making cells into efficient factories is challenging because cells have evolved robust metabolic networks with hard-wired, tightly regulated lines of communication between molecular pathways that resist efforts to divert resources. Here, we will review the current status and challenges...... of metabolic engineering and will discuss how new technologies can enable metabolic engineering to be scaled up to the industrial level, either by cutting off the lines of control for endogenous metabolism or by infiltrating the system with disruptive, heterologous pathways that overcome cellular regulation....

  5. Testing the durability of concrete with neutron radiography

    International Nuclear Information System (INIS)

    The ability of concrete to withstand the penetration of liquid and oxygen can be described as the durability of concrete. The durability of concrete, can in turn, be quantified by certain characteristics of the concrete such as the porosity, sorptivity and permeability. The quantification of neutron radiography images of concrete structures and, therefore, the determination of concrete characteristics validate conventional measurements. This study compares the neutron radiography capability to obtain quantitative data for porosity and sorptivity in concrete to laboratory or conventional measurements. The effects that water to cement ratio and curing time have on the durability of concrete are investigated

  6. XFEM for Thermal Crack of Massive Concrete

    Directory of Open Access Journals (Sweden)

    Guowei Liu

    2013-01-01

    Full Text Available Thermal cracking of massive concrete structures occurs as a result of stresses caused by hydration in real environment conditions. The extended finite element method that combines thermal fields and creep is used in this study to analyze the thermal cracking of massive concrete structures. The temperature field is accurately simulated through an equivalent equation of heat conduction that considers the effect of a cooling pipe system. The time-dependent creep behavior of massive concrete is determined by the viscoelastic constitutive model with Prony series. Based on the degree of hydration, we consider the main properties related to cracking evolving with time. Numerical simulations of a real massive concrete structure are conducted. Results show that the developed method is efficient for numerical calculations of thermal cracks on massive concrete. Further analyses indicate that a cooling system and appropriate heat preservation measures can efficiently prevent the occurrence of thermal cracks.

  7. Conductive concrete wins Popular Science prize

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1997-06-01

    A conductive concrete developed by a research team at IRC (Institute for Research in Construction, National Research Council of Canada) has won a prize in the home technology category because of its possible use in heating homes. Following the award, there have been a number of inquiries regarding possible applications for the concrete. Greatest interests in the concrete have been in its potential to heat buildings by using it as flooring. Other possible applications included de-icing pavements to building warming pads for parking aircraft. Essentially, carbon fibres and conductive particles are added to a concrete mix in such a quantity that they form a network within the mix, ensuring high electrical conductivity. A demonstration project is underway to build a 20 by 80 foot conductive concrete pad to test the material`s capability as a snow removal and de-icing tool.

  8. STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS

    International Nuclear Information System (INIS)

    This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits

  9. Technology for reuse of contaminated concrete constituents

    International Nuclear Information System (INIS)

    During decommissioning activities of nuclear installations, large amounts of contaminated concrete will have to be processed. All this concrete has to be treated and stored as radioactive waste, which implies major economical and environmental consequences. It was shown that the contamination is mainly concentrated in the porous cement stone. By separating this cement stone from the clean dense aggregate particles, a considerable volume reduction can be reached. KEMA has developed, designed and constructed a pilot plant scale test installation for separation of aggregate from contaminated concrete. The separation is based on a thermal treatment followed by milling and sieving. The clean aggregate can be re-used in concrete, whereas the (slightly) contaminated cement stone could be upgraded to a binder for concrete used in the nuclear industry. (author)

  10. Autoclave foam concrete: Structure and properties

    Science.gov (United States)

    Mestnikov, Alexei; Semenov, Semen; Strokova, Valeria; Nelubova, Viktoria

    2016-01-01

    This paper describes the technology and properties of autoclaved foam concrete taking into account practical experience and laboratory studies. The results of study of raw materials and analysis of structure and properties of foam-concrete before and after autoclave treatment are basic in this work. Experimental studies of structure and properties of foam concrete are carried out according to up-to-date methods and equipment on the base of the shared knowledge centers. Results of experimental studies give a deep understanding of properties of raw materials, possible changes and new formations in inner layers of porous material providing the improvement of constructional and operational properties of autoclaved foam concrete. Principal directions of technology enhancement as well as developing of production of autoclave foam concretes under cold-weather conditions in Russia climate are justified.

  11. Electrical Resistance Tomography imaging of concrete

    KAUST Repository

    Karhunen, Kimmo

    2010-01-01

    We apply Electrical Resistance Tomography (ERT) for three dimensional imaging of concrete. In ERT, alternating currents are injected into the target using an array of electrodes attached to the target surface, and the resulting voltages are measured using the same electrodes. These boundary measurements are used for reconstructing the internal (3D) conductivity distribution of the target. In reinforced concrete, the metallic phases (reinforcing bars and fibers), cracks and air voids, moisture gradients, and the chloride distribution in the matrix carry contrast with respect to conductivity. While electrical measurements have been widely used to characterize the properties of concrete, only preliminary results of applying ERT to concrete imaging have been published so far. The aim of this paper is to carry out a feasibility evaluation with specifically cast samples. The results indicate that ERT may be a feasible modality for non-destructive evaluation of concrete. © 2009 Elsevier Ltd. All rights reserved.

  12. Properties of heavyweight concrete produced with barite

    International Nuclear Information System (INIS)

    Heavyweight concrete has been used for the prevention of seepage from radioactive structures due to the harmful effect of radioactive rays to living bodies (i.e., carcinogenic, etc.). The most important point about heavyweight concrete is the determination of w/c ratio. Selected cement dosage should be both high enough to allow for radioactive impermeability and low enough to prevent splits originating from shrinkage. In this study, heavyweight concrete mixtures at different w/c ratios were prepared in order to determine the most favorable w/c ratio of heavyweight concrete produced with barite. Physical and mechanical experiments were first carried out, and then by comparison with the results of other related studies the findings of this study were obtained. At the end of the study, it was found that the most favorable w/c ratio for heavyweight concrete is 0.40 and the cement dosage should not be lower than 350 kg/m3

  13. Studies on recycled aggregates-based concrete.

    Science.gov (United States)

    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

  14. STUDY OF THE EFFECT OF ALUMINUM CONTENT AND C / S RATIO ON THE PHYSICO-MECHANICAL AND THERMAL PROPERTIES OF A LIGHTWEIGHT CONCRETE MADE FROM SAND DUNE

    OpenAIRE

    Z. Damene; M.S. Goual; I. Saiti; N. Benhassine; Ferhat, A.

    2015-01-01

    This research is a contribution to the development of local materials especially in the development of a cellular concrete with dunes sand. This is an experimental study whose objective is to see the influence of the C/S (dosage of cement compared to sand) and the dosage of aluminum on the physico- mechanical and thermal performance of lightweight concrete cellular type. The results showed that the cement compared to the sand has a remarkable effect on the reaction and that on expansion the m...

  15. Radiation Damage In Reactor Cavity Concrete

    Energy Technology Data Exchange (ETDEWEB)

    Field, Kevin G [ORNL; Le Pape, Yann [ORNL; Naus, Dan J [ORNL; Remec, Igor [ORNL; Busby, Jeremy T [ORNL; Rosseel, Thomas M [ORNL; Wall, Dr. James Joseph [Electric Power Research Institute (EPRI)

    2015-01-01

    License renewal up to 60 years and the possibility of subsequent license renewal to 80 years has established a renewed focus on long-term aging of nuclear generating stations materials, and recently, on concrete. Large irreplaceable sections of most nuclear generating stations include concrete. The Expanded Materials Degradation Analysis (EMDA), jointly performed by the Department of Energy, the Nuclear Regulatory Commission and Industry, identified the urgent need to develop a consistent knowledge base on irradiation effects in concrete. Much of the historical mechanical performance data of irradiated concrete does not accurately reflect typical radiation conditions in NPPs or conditions out to 60 or 80 years of radiation exposure. To address these potential gaps in the knowledge base, The Electric Power Research Institute and Oak Ridge National Laboratory are working to disposition radiation damage as a degradation mechanism. This paper outlines the research program within this pathway including: (i) defining the upper bound of the neutron and gamma dose levels expected in the biological shield concrete for extended operation (80 years of operation and beyond), (ii) determining the effects of neutron and gamma irradiation as well as extended time at temperature on concrete, (iii) evaluating opportunities to irradiate prototypical concrete under accelerated neutron and gamma dose levels to establish a conservative bound and share data obtained from different flux, temperature, and fluence levels, (iv) evaluating opportunities to harvest and test irradiated concrete from international NPPs, (v) developing cooperative test programs to improve confidence in the results from the various concretes and research reactors, (vi) furthering the understanding of the effects of radiation on concrete (see companion paper) and (vii) establishing an international collaborative research and information exchange effort to leverage capabilities and knowledge.

  16. Design of concrete for high flowability: Progress report of fib task group 4.3

    NARCIS (Netherlands)

    Schmidt, W.; Grunewald, S.; Ferrara, L.; Dehn, F.

    2015-01-01

    Flowable concretes can differ significantly from traditional vibrated concrete. Concrete types like selfcompacting concrete (SCC), ultra-high performance concrete (UHPC) and high performance fibre reinforced cementitious composites (HPFRCCs) require novel mix design approaches. This has consequences

  17. Examination of Behavior of Fresh Concrete Under Pressure

    Science.gov (United States)

    Yücel, K. T.

    2012-05-01

    Transporting fresh concrete constitutes a significant part of the production process. Transferring ready-mixed concrete on-site is done using concrete pumps. Recent developments in concrete technology, and in mineral and chemical additives, have resulted in new developments in pumping techniques and the use of different concrete mixtures and equipment. These developments required further knowledge of the behavior of fresh concrete under pressure. Two criteria were determined for the pumpability of concrete: the power required to move the concrete or of the repulsive force; and the cohesion of the fresh concrete. It would be insufficient to relate pumpability to these two criteria; the values of segregation pressure, diffusion ability, water retention capacity, and side friction of the mixture are significant parameters in ensuring that concrete is pumped freely along the pipe. To solve the pumpability problem, friction stresses should be determined as a function of the linear pressure gradient, the pressure leading to segregation of the fresh concrete should be determined, and tests for the bleeding of concrete under pressure should be examined. The scope of the research is the examination of the behavior of fresh concrete under pressure. To determine the segregation pressures, a test apparatus was designed for the bleeding of concrete under pressure. The main purpose of the study is to determine whether the concrete can be pumped easily and whether it will lose its cohesion during the pumping, based on tests of concrete workability and bleeding of concrete under pressure.

  18. The State of Cellular Probes

    OpenAIRE

    Yim, Youngbin

    2003-01-01

    Cellular probe technology is one of several potentially promising technologies for obtaining accurate travel time information. In 1996, the Federal Communications Commission (FCC) mandated E911 requirements that cellular location be provided when 911 emergency calls come in to emergency management authorities. The E911 requirements allow 50 -300 meters from the emergency call location, depending on the type of cellular phone technology used and whether handset-based or network-based solutions...

  19. Never-ageing cellular senescence

    OpenAIRE

    Ogrunc, Müge; d’Adda di Fagagna, Fabrizio

    2011-01-01

    Cellular senescence was historically discovered as a form of cellular ageing of in vitro cultured cells. It has been under the spotlight following the evidence of oncogene-induced senescence in vivo and its role as a potent tumour suppressor mechanism. Presently, a PubMed search using keywords ‘cellular senescence and cancer’ reveals 8398 number of references (by April 2011) showing that while our knowledge of senescence keeps expanding, the complexity of the phenomenon keeps us – researchers...

  20. A Failure Criterion for Concrete

    DEFF Research Database (Denmark)

    Ottosen, N. S.

    1977-01-01

    A four-parameter failure criterion containing all the three stress invariants explicitly is proposed for short-time loading of concrete. It corresponds to a smooth convex failure surface with curved meridians, which open in the negative direction of the hydrostatic axis, and the trace in the...... deviatoric plane changes from almost triangular to a more circular shape with increasing hydrostatic pressure. The formulation of the criterion in terms of one function for all stress states facilitates its use in structural calculations. The criterion is demonstrated to be in good agreement with...... experimental results over a wide range of stress states, including both triaxial tests along the tensile and the compressive meridian and biaxial tests. The values of the four parameters are determined so that they only depend on the ratio of uniaxial tensile to compressive strength, and parameter values are...

  1. 'PATRE': High speed concrete scabbling

    International Nuclear Information System (INIS)

    The decommissioning of a nuclear installation requires the complete and thorough decontamination of the buildings before dismantling to green field. This decontamination generally consists in cleaning and scabbling when necessary the concrete walls and floors. Up to now these works were often performed with hand-held machines, with limited power, and therefore were very long and had a high man-power content. PATRE is a concept which mechanizes the process, and allows the use of high power scabbling machines, thus allowing to reach much higher speed than with manual operations. The first tests with PATRE showed the following results: - 10 mm scabbling at a rate of 8 to 10 m2/h, - 45 mm scabbling, with 4 passes at a global rate of 1.5 m2/h

  2. Analytical Study Of Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Hosam A. Dahaam

    2013-05-01

    Full Text Available Nonlinear finite element analyses is carried out using the ANSYS11 program to predict the ultimate load for two different types of reinforced concrete continuous two-span deep beams. Results of comparing analytical with  experimental data demonstrates the accuracy of the program. The effects of longitudinal reinforcement and web openings are studied and showed that the longitudinal reinforcement at top and middle region has little effect on the ultimate load, and the effect of web opening location has  great effect on the ultimate load especially when the load path passes through the openings centerline. Web opening location also has  great effect on values and distribution of shear and normal stresses especially at opening region.   

  3. SA-based concrete seismic stress monitoring: a case study for normal strength concrete

    Science.gov (United States)

    Hou, S.; Zhang, H. B.; Ou, J. P.

    2016-09-01

    The stress history of concrete structures that have survived an earthquake can serve as a critical index to evaluate the health of the structure. There are currently few reliable monitoring methods to assess concrete stress after a seismic event. Piezoelectric-based smart aggregate (SA) provides an innovative experimental approach to monitor stress on concrete. The principle of SA-based concrete seismic stress monitoring is based on the assumption that concrete stress can be reliably predicted by the average output voltages of limited SAs with an acceptable margin of error. In this study, the meso-scale randomness of concrete was evaluated throughout the overall stress range of concrete and the influence of different load paths was considered. Four cylindrical specimens of normal strength concrete were embedded with a total of 24 SAs. The SA output sensitivity curve in the paths of loading–unloading with different amplitudes and monotonic loading up to failure was obtained. Monitoring errors were analyzed during pre- and post-peak stages from the experimental results. This research suggests that SA-based concrete seismic stress monitoring for normal strength concrete is reliable.

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

    International Nuclear Information System (INIS)

    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

  5. Active Cellular Nematics

    Science.gov (United States)

    Duclos, Guillaume; Erlenkaemper, Christoph; Garcia, Simon; Yevick, Hannah; Joanny, Jean-François; Silberzan, Pascal; Biology inspired physics at mesoscales Team; Physical approach of biological problems Team

    We study the emergence of a nematic order in a two-dimensional tissue of apolar elongated fibroblast cells. Initially, these cells are very motile and the monolayer is characterized by giant density fluctuations, a signature of far-from-equilibrium systems. As the cell density increases because of proliferation, the cells align with each other forming large perfectly oriented domains while the cellular movements slow down and eventually freeze. Therefore topological defects characteristic of nematic phases remain trapped at long times, preventing the development of infinite domains. By analogy with classical non-active nematics, we have investigated the role of boundaries and we have shown that cells confined in stripes of width smaller than typically 500 µm are perfectly aligned in the stripe direction. Experiments performed in cross-shaped patterns show that both the number of cells and the degree of alignment impact the final orientation. Reference: Duclos G., Garcia S., Yevick H.G. and Silberzan P., ''Perfect nematic order in confined monolayers of spindle-shaped cells'', Soft Matter, 10, 14, 2014

  6. Monitoring durability of new concrete bridge decks

    Science.gov (United States)

    Aktan, Haluk M.; Yaman, Ismail O.; Staton, John F.

    2001-08-01

    The ND durability monitoring procedure, which measures the soundness of field concrete, is based on the fundamental relationship between ultrasonic pulse velocity (UPV) and permeability of an elastic medium. An experimental study documented adequate sensitivity between UPV and concrete permeability. The durability monitoring procedure is based on a parameter developed as part of this study and called paste quality loss (PQL) which is computed from the probability density function parameters of ultrasonic pulse velocity measurements taken from standard and field concrete. For PQL computation, measurements taken on standard concrete specimens, which are made from field concrete mixture, are compared to field measurements. The verification tests on 1000 mm x 1500 mm x 230 mm lab-deck specimens indicated that the PQL parameter computed from the UPV measurements as early as the 28th day is a good predictor of soundness. The UPV measurements made at increasing age of concrete very clearly document the rapid loss of soundness of improperly cured concrete decks. Deck replacement projects on three NHS bridges were used in the implementation of durability monitoring by PQL (paste quality loss) evaluation. The respective 56-day PQL's were calculated as 15%, 31% and 9% indicating a significant variability in the three bridges.

  7. Self-cleaning geopolymer concrete - A review

    Science.gov (United States)

    Norsaffirah Zailan, Siti; Mahmed, Norsuria; Bakri Abdullah, Mohd Mustafa Al; Sandu, Andrei Victor

    2016-06-01

    Concrete is the most widely used construction materials for building technology. However, cement production releases high amounts of carbon dioxide (CO2) to the atmosphere that leads to increasing the global warming. Thus, an alternative, environmental friendly construction material such as geopolymer concrete has been developed. Geopolymer concrete applies greener alternative binder, which is an innovative construction material that replaces the Portland cement. This technology introduced nano-particles such as nanoclay into the cement paste in order to improve their mechanical properties. The concrete materials also have been developed to be functioned as self-cleaning construction materials. The self-cleaning properties of the concrete are induced by introducing the photocatalytic materials such as titania (TiO2) and zinc oxide (ZnO). Self-cleaning concrete that contains those photocatalysts will be energized by ultraviolet (UV) radiation and accelerates the decomposition of organic particulates. Thus, the cleanliness of the building surfaces can be maintained and the air surrounding air pollution can be reduced. This paper briefly reviews about self-cleaning concrete.

  8. Life Cycle Assessment of Completely Recyclable Concrete

    Directory of Open Access Journals (Sweden)

    Mieke De Schepper

    2014-08-01

    Full Text Available Since the construction sector uses 50% of the Earth’s raw materials and produces 50% of its waste, the development of more durable and sustainable building materials is crucial. Today, Construction and Demolition Waste (CDW is mainly used in low level applications, namely as unbound material for foundations, e.g., in road construction. Mineral demolition waste can be recycled as crushed aggregates for concrete, but these reduce the compressive strength and affect the workability due to higher values of water absorption. To advance the use of concrete rubble, Completely Recyclable Concrete (CRC is designed for reincarnation within the cement production, following the Cradle-to-Cradle (C2C principle. By the design, CRC becomes a resource for cement production because the chemical composition of CRC will be similar to that of cement raw materials. If CRC is used on a regular basis, a closed concrete-cement-concrete material cycle will arise, which is completely different from the current life cycle of traditional concrete. Within the research towards this CRC it is important to quantify the benefit for the environment and Life Cycle Assessment (LCA needs to be performed, of which the results are presented in a this paper. It was observed that CRC could significantly reduce the global warming potential of concrete.

  9. Behavior of compacted clay-concrete interface

    Institute of Scientific and Technical Information of China (English)

    R.R. SHAKIR; Jungao ZHU

    2009-01-01

    Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus. The samples, having same dry density with different water content ratio, were prepared.Two types of concrete with different surface roughness, i.e., relatively smooth and relatively rough surface rough-ness, were also prepared. The main objectives of this paper are to show the effect of water content, normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface. The following were concluded in this study: 1) the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16% for the case of rough concrete surface where the shear failure occurs in the body of the clay sample; 2) the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface; 3) two types of interface failure mechanism may change each other with different water content ratio; 4) the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.

  10. Durability of heavyweight concrete containing barite

    International Nuclear Information System (INIS)

    The supplementary waste barite aggregates deposit in Osmaniye, southern Turkey, has been estimated at around 500 000 000 tons based on 2007 records. The aim of the present study is to investigate the durability of concrete incorporating waste barite as coarse and river sand (RS), granule blast furnace slag (GBFS), granule basaltic pumice (GBP) and ≤ 4 mm granule barite (B) as fine aggregates. The properties of the fresh concrete determined included the air content, slump, slump loss and setting time. They also included the compressive strength, flexural and splitting tensile strengths and Young's modulus of elasticity, resistance to abrasion and sulphate resistance of hardened concrete. Besides these, control mortars were prepared with crushed limestone aggregates. The influence of waste barite as coarse aggregates and RS, GBFS, GBP and B as fine aggregates on the durability of the concretes was evaluated. The mass attenuation coefficients were calculated at photon energies of 1 keV to 100 GeV using XCOM and the obtained results were compared with the measurements at 0.66 and 1.25 MeV. The results showed the possibility of using these waste barite aggregates in the production of heavy concretes. In several cases, some of these properties have been improved. Durability of the concrete made with these waste aggregates was improved. Thus, these materials should be preferably used as aggregates in heavyweight concrete production. (orig.)

  11. Self Compacting Concrete And Its Properties

    Directory of Open Access Journals (Sweden)

    S. Mahesh

    2014-08-01

    Full Text Available Self-compacting concrete (SCC, which flows under its own weight and doesn’t require any external vibration for compaction, has revolutionized concrete placement. Such concrete should have relatively low yield value to ensure high flow ability, a moderate viscosity to resists segregation and bleeding and must maintain its homogeneity during transportation, placing and curing to ensure adequate structural performance and long term durability. Self-compacting concrete (SCC can be defined as a fresh concrete which possesses superior flow ability under maintained stability (i.e. no segregation thus allowing self-compaction that is, material consolidation without addition of energy. Self-compacting concrete is a fluid mixture suitable for placing in structures with Congested reinforcement without vibration and it helps in achieving higher quality of surface finishes. However utilization of high reactive Metakaolin and Flyash asan admixtures as an effective pozzolan which causes great improvement in the porestructure. The relative proportions of key components are considered by volumerather than by mass. self compacting concrete (SCC mix design with 29% of coarse aggregate, replacement of cement with Metakaolin and class F flyash, combinations of both and controlled SCC mix with 0.36 water/cementitious ratio(by weight and388 litre/m3 of cement paste volume. Crushed granite stones of size 16mm and12.5mm are used with a blending 60:40 by percentage weight of total coarse aggregate. Self-compacting concrete compactibility is affected by the characteristics of materials and the mix proportions; it becomes necessary to evolve a procedure formix design of SCC. The properties of different constituent materials used in this investigation and its standard tests procedures for acceptance characteristics of self compacting concrete such as slump flow, V-funnel and L-Box are presented.

  12. Ultra high performance concrete dematerialization study

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-03-01

    Concrete is the most widely used building material in the world and its use is expected to grow. It is well recognized that the production of portland cement results in the release of large amounts of carbon dioxide, a greenhouse gas (GHG). The main challenge facing the industry is to produce concrete in an environmentally sustainable manner. Reclaimed industrial by-proudcts such as fly ash, silica fume and slag can reduce the amount of portland cement needed to make concrete, thereby reducing the amount of GHGs released to the atmosphere. The use of these supplementary cementing materials (SCM) can also enhance the long-term strength and durability of concrete. The intention of the EcoSmart{sup TM} Concrete Project is to develop sustainable concrete through innovation in supply, design and construction. In particular, the project focuses on finding a way to minimize the GHG signature of concrete by maximizing the replacement of portland cement in the concrete mix with SCM while improving the cost, performance and constructability. This paper describes the use of Ductal{sup R} Ultra High Performance Concrete (UHPC) for ramps in a condominium. It examined the relationship between the selection of UHPC and the overall environmental performance, cost, constructability maintenance and operational efficiency as it relates to the EcoSmart Program. The advantages and challenges of using UHPC were outlined. In addition to its very high strength, UHPC has been shown to have very good potential for GHG emission reduction due to the reduced material requirements, reduced transport costs and increased SCM content. refs., tabs., figs.

  13. 47 CFR 22.909 - Cellular markets.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cellular markets. 22.909 Section 22.909... Cellular Radiotelephone Service § 22.909 Cellular markets. Cellular markets are standard geographic areas used by the FCC for administrative convenience in the licensing of cellular systems. Cellular...

  14. Influence of Additives on Reinforced Concrete Durability

    Directory of Open Access Journals (Sweden)

    Neverkovica Darja

    2014-12-01

    Full Text Available The article presents the results of the research on carbonation and chloride induced corrosion mechanisms in reinforced concrete structures, based on three commercially available concrete admixtures: Xypex Admix C-1000, Penetron Admix and Elkem Microsilica. Carbonation takes place due to carbon dioxide diffusion, which in the required amount is present in the air. Chlorides penetrate concrete in case of the use of deicing salt or structure exploitation in marine atmosphere. Based on the implemented research, Elkem Microsilica is the recommended additive for the use in aggressive environmental conditions. Use of Xypex Admix C-1000 and Penetron Admix have only average resistance to the aggressive environmental impact.

  15. High temperature regime of corium concrete interactions

    International Nuclear Information System (INIS)

    The high temperature regime of corium concrete interaction is examined from the point of view of its sensitivity to the completeness of reaction of the gaseous concrete decomposition products with the metallic components of the melt. A program based on the DECOMP modeling approach has been utilized for this purpose. For a corium/concrete heat transfer that is consistent with the erosion rates observed in the BETA experiments the primary effect of the extent of reaction completeness is on the duration of the high temperature regime. This implies a potentially important effect on the aerosols stripped out during this portion of the interaction

  16. Transient heating effect on high strength concrete

    International Nuclear Information System (INIS)

    This study shows some differences in the properties and the behaviour at high temperature of two concretes (ordinary and high strength) made with the same calcareous aggregates. During heating tests at 1 C min-1, cylindrical samples of diameter 160 x 320 mm of high strength concrete, more dense, may explode in a critical temperature zone between 250 and 300 C. Differences in behaviour between OC and HSC appeared at high temperatures: there were disparities especially in thermo-hydric transfer, porosity and thermal stability. The dense microstructure of high strength concrete was found to slow up the escape of vaporized water. (orig.)

  17. Meshfree Sequentially Linear Analysis of Concrete

    OpenAIRE

    Salam Al-Sabah, Abd; Laefer, Debra F.

    2015-01-01

    A new, meshfree method employing the node-based, smoothed point interpolation method (NS-PIM) is presented as an alternative to the nonlinear finite-element approach for concrete members. The nonlinear analysis is replaced by sequentially linear analyses (SLA), and a smeared, fixed concrete cracking model was used. A notched concrete beam was employed for validation. Using a crack band width factor of 2.0 and 10-mm nodal spacing, the peak load differed by only 3.5% from experimental results. ...

  18. Fibre Optic Protection System for Concrete Structures

    Institute of Scientific and Technical Information of China (English)

    J.S.Leng; A.Hameed; D.Winter; R.A.Barnes; G.C.Mays; G.F.Fernando

    2006-01-01

    The design concepts, modelling and implementation of various fibre optic sensor protection systems for development in concrete structures were investigated. Design concepts and on-site requirements for surface-mounted and embedded optical fibre sensor in concrete were addressed. Finite element (FE) modelling of selected sensor protection systems in strain-transfer efficiency from the structure to the sensing region was also studied. And experimental validation of specified sensor protection system was reported. Results obtained indicate that the protection system for the sensors performs adequately in concrete environment and there is very good correlation between results obtained by the protected fibre optic sensors and conventional electrical resistance strain gauges.

  19. Investigation of electrokinetic decontamination of concrete

    International Nuclear Information System (INIS)

    Experiments have been conducted to investigate the capabilities of electrokinetic decontamination of concrete. Batch equilibration studies have determined that the loading of cesium and strontium on concrete may be decreased using electrolyte solutions containing competing cations, while solubilization of uranium and cobalt, that precipitate at high pH, will require lixiviants containing complexing agents. Dynamic electrokinetic experiments showed greater mobility of cesium than strontium, while some positive results were obtained for the transport of cobalt through concrete using EDTA and for uranium using carbonate

  20. Fatigue in Breakwater Concrete Armour Units

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    1985-01-01

    The reliability of rubble mound breakwaters depends on the hydraulic stability and the mechanical strength of the armour units. The paper deals with the important aspect of fatigue related to the strength of concrete armour units. Results showing significant fatigue from impact tests with Dolosse...... made of unreinforced and steel fibre reinforced flyash concrete are presented. Moreover universal graphs for fatigue in armour units made of conventional unreinforced concrete exposed to impact load and pulsating load are presented. The effect of fibre reinforcement and the implementation of fatigue in...

  1. Flexural Behavior of Textile-Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Volkova Anna

    2016-01-01

    Full Text Available This paper deals with the flexural behaviour of textile-reinforced concrete (TRC. Two samples of TRC made of high strength reinforcing fabrics made of glass and carbon rovings were produced. Three-point bending test was carried out to examine the flexural performance of the developed samples. The maximum flexural strength and reinforcement efficiency were calculated. Experimental results showed that that all types of applied fabric reinforcement contributed to increases strength as compared to nonreinforced concrete. Furthermore, the deformation behavior of reinforced concrete was analyzed. The advantage is in higher residual load-bearing capacity, which allows maintaining the integrity of the structure.

  2. Concrete Strength for Fire Safety Design

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    2005-01-01

    Idealized data are derived for the compressive strength of a number of concretes for fire safety design. The data are derived from the authors own research including test series not published before and from more than 400 other test series comprising approximately 3000 specimens known from...... literature and personal contact. The data cover a variety of concretes with aggregates such as siliceous materials, limestone, granite, sea gravel, pumice, and expanded clay to fire resistant concrete based on chamotte or Danish mo-clay. Processes are briefly described, which are responsible for the...

  3. Reusing recycled aggregates in structural concrete

    Science.gov (United States)

    Kou, Shicong

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

  4. Carbonation and CO2 uptake of concrete

    International Nuclear Information System (INIS)

    This study developed a reliable procedure to assess the carbon dioxide (CO2) uptake of concrete by carbonation during the service life of a structure and by the recycling of concrete after demolition. To generalize the amount of absorbable CO2 per unit volume of concrete, the molar concentration of carbonatable constituents in hardened cement paste was simplified as a function of the unit content of cement, and the degree of hydration of the cement paste was formulated as a function of the water-to-cement ratio. The contribution of the relative humidity, type of finishing material for the concrete surface, and the substitution level of supplementary cementitious materials to the CO2 diffusion coefficient in concrete was reflected using various correction factors. The following parameters varying with the recycling scenario were also considered: the carbonatable surface area of concrete crusher-runs and underground phenomena of the decreased CO2 diffusion coefficient and increased CO2 concentration. Based on the developed procedure, a case study was conducted for an apartment building with a principal wall system and an office building with a Rahmen system, with the aim of examining the CO2 uptake of each structural element under different exposure environments during the service life and recycling of the building. As input data necessary for the case study, data collected from actual surveys conducted in 2012 in South Korea were used, which included data on the surrounding environments, lifecycle inventory database, life expectancy of structures, and recycling activity scenario. Ultimately, the CO2 uptake of concrete during a 100-year lifecycle (life expectancy of 40 years and recycling span of 60 years) was estimated to be 15.5%–17% of the CO2 emissions from concrete production, which roughly corresponds to 18%–21% of the CO2 emissions from the production of ordinary Portland cement. - Highlights: • CO2 uptake assessment approach owing to the concrete

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

    Science.gov (United States)

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

    2014-01-01

    Currently, reuse of solid waste from disused infrastructures is an important environmental issue to study. In this research, polymer concrete was developed by mixing orthophthalic unsaturated polyester resin, artificial microfillers (calcium carbonate), and waste aggregates (basalt and limestone) coming from the recycling process of concrete sleepers. The variation of the mechanical and physical properties of the polymer concrete (compressive strength, flexural strength, modulus of elasticity, density, and water absorption) was analyzed based on the modification of different variables: nature of the recycled aggregates, resin contents (11 wt%, 12 wt%, and 13 wt%), and particle-size distributions of microfillers used. The results show the influence of these variables on mechanical performance of polymer concrete. Compressive and flexural strength of recycled polymer concrete were improved by increasing amount of polyester resin and by optimizing the particle-size distribution of the microfillers. Besides, the results show the feasibility of developing a polymer concrete with excellent mechanical behavior. PMID:25243213

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

    Directory of Open Access Journals (Sweden)

    Francisco Carrión

    2014-01-01

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

  7. Mechanical properties of concrete and reinformed concrete at high temperatures exceeding 100 deg C

    International Nuclear Information System (INIS)

    In LWR plants etc. the reinforced concrete structures are used under high-temperature environment. In order to grasp their high-temperature behavior, experimental studies have been conducted at temperatures from 100 deg C up to 500 deg C, allowing the moisture in concrete to dissipate freely. In strength and elastic modulus of the concrete there is evident temperature dependence, but the data scatter considerably depending on the experimental conditions; their quantitative evaluation is impossible. Concerning mechanical properties of reinforcing bars, the temperature dependence of their yield-point strength and the stress-strain characteristic following the yield have influences on the yield point and the ultimate yield point of the reinforced concrete beam, respectively. In high-temperature behavior of the reinforced concrete beam, the difference in thermal expansion coefficient between reinforcing bars and concrete has also influence. (Mori, K.)

  8. 29 CFR 1926.704 - Requirements for precast concrete.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 8 2010-07-01 2010-07-01 false Requirements for precast concrete. 1926.704 Section 1926..., DEPARTMENT OF LABOR (CONTINUED) SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION Concrete and Masonry Construction § 1926.704 Requirements for precast concrete. (a) Precast concrete wall units, structural...

  9. Design of ecological concrete by particle packing optimization

    NARCIS (Netherlands)

    Fennis, S.A.A.M.

    2011-01-01

    The goal of this research project on Ecological Concrete was to reduce the CO2-emission of concrete and to reuse secondary materials form concrete production and other industries simultaneously. This also minimizes the use of natural resources and the production costs. To replace cement in concrete

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

    OpenAIRE

    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,...

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

    OpenAIRE

    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...

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

    OpenAIRE

    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...

  13. Influence of different sizes of concrete and roller compacted concrete on double-K fracture parameters

    OpenAIRE

    Liu Chunjiang; Zhang Huabo; Lv Ninghua

    2016-01-01

    Affected by physical properties of various components, characteristics and stress states of junction surface and other multiple factors, concrete, as a kind of multi-phase composite material, has complicated failure mechanism, thus making its fracture mechanism research difficult. But concrete has been widely used in engineering construction, so research on concrete fracture theory is of important realistic significance and construction value. This study discusses influence rule o...

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

    OpenAIRE

    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...

  15. Predicting the Durability of Concrete Structures, including Sulfate Corrosion of Concrete

    OpenAIRE

    V.P. Selyaev; V.A. Neverov; P.V. Selyaev; E.V. Sorokin; O.A. Yudina

    2014-01-01

    Multiple data on the examination of concrete structures indicate that under the influence of various factors (temperature, humidity, gaseous medium) carrying capacity and rigidity during operation are reduced. The problems of assessing the residual life and durability of concrete structures are considered in the article. Experimental studies on the interaction of the concrete samples with aggressive sulfate medium are conducted. By measuring the micro-hardness, isochrones of degradations,...

  16. Rehabilitation of concrete structures using Ultra-High Performance Fibre Reinforced Concrete

    OpenAIRE

    Brühwiler, E.; Denarié, E.

    2008-01-01

    An original concept is presented for the rehabilitation of concrete structures. The main idea is to use Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) to “harden” those zones where the structure is exposed to severe environmental and high mechanical loading. All other parts of the structure remain in conventional structural concrete as these parts are subjected to relatively moderate exposure. This conceptual idea combines efficiently protection and resis-tance properties of UHPFRC...

  17. Potential reduction of concrete deterioration through controlled DEF in hydrated concrete

    OpenAIRE

    Lubej, Samo; Radosavljevic, Milan

    2015-01-01

    Delayed ettringite formation (DEF) is a chemical reaction with proven damaging effects on hydrated concrete. Ettringite crystals can cause cracks and their widening due to pressure on cracked walls caused by the positive volume difference in the reaction. Concrete may show improvements in strength at early ages but further growth of cracks causes widening and spreading through the concrete structure. In this study, finely dispersed crystallization nuclei achieved by adding air-entraining agen...

  18. RESEARCH OF ADHESIVE STRENGTH OF NEW CONCRETE LAYER WITH A SURFACE OF OLD CONCRETE

    Directory of Open Access Journals (Sweden)

    Bulgakov Boris Igorevich

    2016-04-01

    Full Text Available Concrete is a material very commonly used in modern construction, each year over 4 billion m3 of concrete is used around the world. In the recent years high-quality fine grain and other types of concrete allow giving the modern creation city buildings new architectural expressivity, meeting the requirements of the XXI century. The trend of using of these new types of concrete is also applied in the construction of tunnel systems and the subway. The fine-grained high performance concrete obtained by using a mixture of organo-mineral additives and fiber reinforcement, compares fovourably with ordinary fine-grained concrete, namely its bending and tensile strength is higher, it has good resistance to shock impacts and fatigue, as well as crack resistance, water resistance and resistance to erosion. So this type of fine-grained high performance concrete is suitable for the construction of subway tunnels and other special objects. When evaluating the concrete performance in underground rock layers subjected to complex mechanical forces, it is important to take into account the stress of metro upon departure and stopping at the stations. The article presents a new experimental method of determining the adhesion strength of fine-grained high performance concrete layer freshly poured on the surface of old concrete in the process of construction and repair of underground. The result of this method application showed that fine-grained high performance concrete is capable of skid resistance higher than 55 % compared to regular fine-grained concrete without additives.

  19. Recycling of fresh concrete exceeding and wash water in concrete mixing plants

    OpenAIRE

    Férriz Papí, J. A.

    2014-01-01

    The exceeding concrete and washing equipment water are a matter to solve in concrete production. This paper explains several possibilities for recycling and analyses the products obtained with one recycling equipment. The objective of this work is to study the possibility to increase the percentage of recycling in new mixes. The developed study relates wash water density and fine particles content. Besides, mortar and concrete samples were tested introducing different quantities of these fine...

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

    OpenAIRE

    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. DEFLECTION CALCULATION OF REINFORCED CONCRETE FLEXURAL ELEMENTS WITH THE TOP LAYER MADE OF HIGH QUALITY CONCRETE

    OpenAIRE

    Potapov Yuriy Borisovich; Barabash Dmitriy Evgen’evich; Rogatnev Yuriy Fedorovich; Panfilov Dmitriy Vyacheslavovich; Mehdi Jawid Mohammad

    2016-01-01

    One of the main requirements to the operational integrity of reinforced concrete flexural elements is nonexeedance of the deflection limits at the assumed load. It is possible to provide the given requirement using different methods, one of which is the production of a sandwich construction of the concretes with different strength. The article presents the results of theoretical and experimental investigations of the deflection of reinforced concrete beams with the top layer made of high-qual...

  2. Possibilities of Using Concrete Waste in the Further Production of Concrete Composite

    OpenAIRE

    Olga Finoženok; Ramunė Žurauskienė

    2011-01-01

    Concrete is a secure building material due to outstanding characteristics of which used in different constructions all over the world. A number of scientists examined the use of different waste products in building material manufacture in order to economize the input of energy and natural resources. On the basis of conducted tests, we can maintain that after 28 days of consolidation, the strength of concrete in the process of manufacturing of which the coarse aggregate of concrete waste was u...

  3. Bond of Reinforcement in Concrete Applied to Concrete Quality Control: The Bottle Bond Test

    OpenAIRE

    García Taengua, Emilio José; Martí Vargas, José Rocío; Serna Ros, Pedro

    2014-01-01

    This paper presents the results of an experimental research dealing with bond strength as a parameter for concrete quality control. To this end, a low-cost testing technique has been developed: the Bottle Bond Test (BBT). Specimens for the BBT are produced by casting concrete into empty plastic bottles (used as moulds) with a reinforcing bar longitudinally centred. The result is a bottle-shaped concrete specimen with an embedded rebar, which is pulled out to determine bond strength. Different...

  4. MIMO Communication for Cellular Networks

    CERN Document Server

    Huang, Howard; Venkatesan, Sivarama

    2012-01-01

    As the theoretical foundations of multiple-antenna techniques evolve and as these multiple-input multiple-output (MIMO) techniques become essential for providing high data rates in wireless systems, there is a growing need to understand the performance limits of MIMO in practical networks. To address this need, MIMO Communication for Cellular Networks presents a systematic description of MIMO technology classes and a framework for MIMO system design that takes into account the essential physical-layer features of practical cellular networks. In contrast to works that focus on the theoretical performance of abstract MIMO channels, MIMO Communication for Cellular Networks emphasizes the practical performance of realistic MIMO systems. A unified set of system simulation results highlights relative performance gains of different MIMO techniques and provides insights into how best to use multiple antennas in cellular networks under various conditions. MIMO Communication for Cellular Networks describes single-user,...

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Influences of Reinforcement on Differential Drying Shrinkage of Concrete

    Institute of Scientific and Technical Information of China (English)

    GAO Xiaojian; QU Guangbin; ZHANG Ailian

    2012-01-01

    Shrinkage strain of concrete specimen with different reinforcement configuration was measured at various depths from the exposed surface by using several pairs of displacement sensors.Only one surface of the concrete specimen was exposed to dry condition during the experiment.The results show that differential shrinkage strain occurs in both plain and steel reinforced concrete specimens according to depths from the exposed surface.A higher reinforcement ratio results in a greater restraint against shrinkage of concrete nearby reinforcement rebar and a worse differential shrinkage strain distribution in the concrete specimen.The restraint against shrinkage of concrete becomes lower with the increasing distance from reinforcement rebar.Under the same reinforcement arrangement,a higher free shrinkage of concrete leads to a stronger restraint against shrinkage and a higher shrinkage stress formation in local concrete.The relationship between shrinkage strain and reduction of relative humidity in reinforced concrete structure is far different from that in plain concrete.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Comparison of the fracture process of the rubberized concrete and plain concrete under bending load

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Acoustic emission (AE) technique is employed to investigate the damage process of the notched plain concrete and rubberized concrete specimens under 3-point bending load.AE signals in the fracture process of notched specimens are illustrated by analyzing the distribution of amplitude and hit rate of AE signals.AE signals in the rubberized concrete have lower activity and amplitude than in the plain concrete.By AE location analysis,it is found that the high energy events mainly are distributed near the notch tip.According to AE energy,the fracture process zone (FPZ) is determined.By comparing the FPZ of both concretes,it is found that the incorporation of rubber particles in concrete can greatly alleviate the damage process of concrete specimens and the damage zone in the rubberized concrete is much smaller than in the plain concrete.The moment tensor is also used to analyze the type of cracks and it is found that tensile cracks dominate the early period of loading,while shear cracks become dominant with propagation of cracks in late load period.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Pentek concrete scabbling system: Baseline report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-07-31

    The Pentek scabbling technology was tested at Florida International University (FIU) and is being evaluated as a baseline technology. This report evaluates it for safety and health issues. It is a commercially available technology and has been used for various projects at locations throughout the country. The Pentek concrete scabbling system consisted of the MOOSE{reg_sign}, SQUIRREL{reg_sign}-I, and SQUIRREL{reg_sign}-III scabblers. The scabblers are designed to scarify concrete floors and slabs using cross-section, tungsten carbide tipped bits. The bits are designed to remove concrete in 318 inch increments. The bits are either 9-tooth or demolition type. The scabblers are used with a vacuum system designed to collect and filter the concrete dust and contamination that is removed from the surface. The safety and health evaluation during the human factors assessment focused on two main areas: noise and dust.

  11. Statistical analysis of ultrasonic measurements in concrete

    Science.gov (United States)

    Chiang, Chih-Hung; Chen, Po-Chih

    2002-05-01

    Stress wave techniques such as measurements of ultrasonic pulse velocity are often used to evaluate concrete quality in structures. For proper interpretation of measurement results, the dependence of pulse transit time on the average acoustic impedance and the material homogeneity along the sound path need to be examined. Semi-direct measurement of pulse velocity could be more convenient than through transmission measurement. It is not necessary to assess both sides of concrete floors or walls. A novel measurement scheme is proposed and verified based on statistical analysis. It is shown that Semi-direct measurements are very effective for gathering large amount of pulse velocity data from concrete reference specimens. The variability of measurements is comparable with that reported by American Concrete Institute using either break-off or pullout tests.

  12. Sequestration of CO2 by concrete carbonation.

    Science.gov (United States)

    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

  13. Frost resistance of fibre reinforced concrete structures

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan De Place

    0.4-1% by volume of fibres cannot replace air entrainment in order to secure a frost resistant concrete; the minimum amount of air needed to make the concrete frost resistant is not changed when adding fibres· the amount of air entrainment must be increased when fibres are added to establish the......Frost resistance of fibre reinforced concrete with 2.5-4.2% air and 6-9% air (% by volume in fresh concrete) casted in the laboratory and in-situ is compared. Steel fibres with hooked ends (ZP, length 30 mm) and polypropylene fibres (PP, CS, length 12 mm) are applied. It is shown that· addition of...

  14. Development of Soda Residue Concrete Expansion Agent

    Institute of Scientific and Technical Information of China (English)

    WANG Bao-min; WANG Li-jiu; M F Mohd Zain; F C Lai

    2003-01-01

    A new type of concrete expansion agent has been successfully developed for the first time in the world by utilizing an industrial waste residue-soda residue and an industrial wasteliquor.Adding 3%-6% of the agent into Portland cement enables a shrinkage-compensating concrete to be prepared.Mortar and concrete containing this expansion agent have better shrinkage-compensating and mechanical properties.The raw materials component,production process,technical properties,micro-analysis of mortar made with this expansion agent,mechanism of expansion and research results are described in this article.The experimental results show that the new type of concrete expansion agent accords with the standard and its main mineral component is xCaO-ySO3-zAl2O3.

  15. Evaluating Deterioration of Concrete by Sulfate Attack

    Institute of Scientific and Technical Information of China (English)

    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.

  16. Modeling of Corrosion-induced Concrete Damage

    DEFF Research Database (Denmark)

    Thybo, Anna Emilie A.; Michel, Alexander; Stang, Henrik

    In the present paper a finite element model is introduced to simulate corrosion-induced damage in concrete. The model takes into account the penetration of corrosion products into the concrete as well as non-uniform formation of corrosion products around the reinforcement. To ac-count for the non......-uniform formation of corrosion products at the concrete/reinforcement interface, a deterministic approach is used. The model gives good estimates of both deformations in the con-crete/reinforcement interface and crack width when compared to experimental data. Further, it is shown that non-uniform deposition of...... corrosion products affects both the time-to cover cracking and the crack width at the concrete surface....

  17. Chloride migration in concrete with superabsorbent polymers

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede

    2015-01-01

    Superabsorbent polymers (SAP) can be used as a means for internal curing of concrete. In the present study, the development of transport properties of concrete with SAP is investigated. The chloride migration coefficient according to NT BUILD 492 is used as a measure of this. Twenty concrete...... mixtures are tested 7, 14, and 28 days after casting. The development of degree of hydration is followed for 20 corresponding paste mixtures. Both when SAP is added with extra water to compensate the SAP water absorption in fresh concrete and without extra water, the internal curing water held by SAP may...... contribute to increase the degree of hydration. No matter if SAP is added with or without extra water, it appears that the so-called gel space ratio can be used as a key parameter to link age and mixture proportions (water-to-cement ratio and SAP dosage) to the resulting chloride migration coefficient; the...

  18. FUETAP concrete - an alternative radioactive waste host

    International Nuclear Information System (INIS)

    These tailored autoclaved concretes (FUETAP concentrates) offer a number of advantages as hosts for a wide variety of radioactive wastes. They are formed at low temperatures and pressures (1000C and 0.1 MPa) from readily available raw materials and require no new processing technology. The extreme latitude in concrete formulations ensures the acceptance of the gamut of waste materials. The leachability of nuclides from the resulting ceramic-like concretes is quite low with essentially no prospect of pressure build-up from long-term self-irradiation in the final storage containers. The solids are thermally stable up to at least 9000C. Additional studies are in progress to verify that FUETAP concretes are acceptable alternative waste hosts for defense, TRU, and commercial high-level radioactive waste. (orig.)

  19. Airplane impacts on reinforced concrete shells

    International Nuclear Information System (INIS)

    Results of nonlinear and ultimate load finite element analyses of reinforced concrete shells subject to airplane impact loads are presented. Algorithmic difficulties and impact-release conditions are discussed. (orig.)

  20. REINFORCED CONCRETE SILO DEMOLITION BY BLASTING

    OpenAIRE

    Josip Krsnik; Zvonimir Ester; Marin Petrov

    1993-01-01

    This paper represents the demolition of reinforced concrete silo by blasting. The loadbearing structure was blasted so that the weight of the silo itself done most of the felling (the paper is published in Croatian).

  1. Use of metallic fibers in concretes

    Directory of Open Access Journals (Sweden)

    Kherbache Souad

    2014-04-01

    Full Text Available The addition of a waste (fibers in construction materials, particularly, the concretes is a technique increasingly used, for several reasons, either ecological, or economic, or to improve some properties in a fresh or hardened state. In our work we studied the behavior of the concrete and the mortar containing metallic fibers resulting from the unit BCR which is in Bordj-Menaiel in Algeria (metallic fibers resulting from the rejection at the end of the domestic operation of silvering of the tools and which is stored in plastic bags which are preserved in metal containers. Our work consists to study the behavior of the concretes and the mortars containing these fibers of cement substitution. We noted that the use of these fibers in the concretes in substitution of cement decreases its of compressive strength and flexural strength but to 10% of waste these strength remain acceptable.

  2. Structure and properties of textile reinforced concrete

    Directory of Open Access Journals (Sweden)

    A.A. Volkova

    2015-11-01

    Full Text Available In this paper the structure and properties of textile-reinforced concrete were investigated. Two types of high strength reinforcing fabrics made of glass and carbon rovings were used in this study. The samples of textile-reinforced concrete were produced. The mechanical properties of the developed samples were determined via a three-point bending test. The maximum flexural strength and reinforcement efficiency were calculated. It was found that the samples with textile reinforcement have higher strength characteristics as compared to nonreinforced concrete. Furthermore, the deformation behavior of reinforced concrete was analyzed. The advantage is in higher residual load-bearing capacity, which allows maintaining the integrity of the structure.

  3. Models of transport processes in concrete

    International Nuclear Information System (INIS)

    An approach being considered by the US Nuclear Regulatory Commission for disposal of low-level radioactive waste is to place the waste forms in concrete vaults buried underground. The vaults would need a service life of 500 years. Approaches for predicting the service life of concrete of such vaults include the use of mathematical models. Mathematical models are presented in this report for the major degradation processes anticipated for the concrete vaults, which are corrosion of steel reinforcement, sulfate attack, acid attack, and leaching. The models mathematically represent rate controlling processes including diffusion, convection, and reaction and sorption of chemical species. These models can form the basis for predicting the life of concrete under in-service conditions. 33 refs., 6 figs., 7 tabs

  4. Constitutive equation of concrete: Mesomechanical isotropic model

    Czech Academy of Sciences Publication Activity Database

    Kafka, Vratislav; Vokoun, David

    2005-01-01

    Roč. 1, č. 2 (2005), s. 183-193. ISSN 1573-6105 Institutional research plan: CEZ:AV0Z20710524 Keywords : plasticity * constitutive modeling * concrete * mesomechanics Subject RIV: JI - Composite Materials

  5. Statistical analysis of concrete creep effects

    International Nuclear Information System (INIS)

    The principal sources of uncertainty in concrete creep effects are the following: uncertainty in the stochastic evolution in time of the mechanism of creep (internal uncertainty); uncertainty in the prediction of the properties of the materials; uncertainty in the stochastic evolution of environmental conditions; uncertainty of the theoretical models; errors of measurement. Interest in the random nature of concrete creep (and shrinkage) effects is discussed. The late beginning of the studies on this subject is perhaps due to their theoretical and computational complexity: nevertheless, since creep and shrinkage affect features of concrete structures as the residual prestressing force in prestressed sections, the stress redistribution in steel-concrete composite beams, deflections and deformations, stress distributions in non-homogenous structures, reactions due to delayed restraints and creep buckling, these studies are very important. This paper is aimed to find the statistics of some of these effects taking into the account the third type of source of uncertainty

  6. Cooling performance evaluation of the concrete cask

    International Nuclear Information System (INIS)

    The concrete cask storage system stores spent fuel by first sealing it within canisters and then containing such canisters inside a concrete cask. This report describes the results of a full-size model test performed to examine the heat dissipation characteristics of the concrete cask and to ascertain its ability to deal with elevated temperature. The specification to which a full-size concrete cask model was fabricated assumed an interim storage of 17x17UO2 fuel that was burned in PWR, estimating the heating value of spent fuel containing canister to be approximately 20 kW apiece. The test, which actually covered canister heating values ranging from 10 kW to 30 kW per unit to allow for temperature variations likely to be experienced in actual operation, verified that the concrete cask member did not exceed temperature limits. Test condition anticipated highest air temperature inside the spent fuel storage facility to be 30degC and, with reference to existing standard, set temperature limits of 65degC or less for the main body of concrete and 90degC or less for the local part as criteria. Preliminary 3-D thermo hydrodynamic analysis done prior to the test indicated that the temperature of the local part of the concrete cask member would be below 90degC. It also confirmed that steel material used as the structural member of the canisters or concrete cask would remain around 200degC even in an area where it was highest, validating that the integrity of such material would pose no problem from the analytical point of view. Heat dissipation performance test conducted in steady state verified that the concrete cask was able to have a sufficient cooling capacity against per-canister heating values in the 10 kW to 30 kW range which had been chosen in anticipation of temperature variation thought to be encountered in actual service. Also, to examine the consequence of the concrete cask having lost its cooling ability, another heat dissipation test was carried out under

  7. Adhesion between high-strength concrete, epoxy resin and CFRP

    OpenAIRE

    Aguiar, J. L. Barroso de; Krzywon, Rafal; Camões, Aires; Gorski, M.; Dawczynski, Szymon

    2008-01-01

    This paper presents a study on the adhesion between high-strength concrete, epoxy resin and CFRP. The adhesion of the high-strength concrete was compared with the same property measured in conventional concrete. Shear tests were made to test adhesion from concretes to epoxy resin. Flexural tests were used to evaluate the adhesion between concretes, epoxy and CFRP. The effect of temperature was also evaluated. For ordinary temperatures (20 ºC) the results showed a better flexural performance o...

  8. Fiber Concrete under Temperature Drop Load with Stochastic FEM

    Institute of Scientific and Technical Information of China (English)

    QI Feng; ZHANG Wen-jin

    2008-01-01

    Plain concrete plate and fiber concrete plate subjected to temperature drop load were analyzed on stochastic finite element method (FEM). It is found that fibers can enhance concrete ability to resist temperature drop load for improving concrete's fracture energy and deferring the crack process. It is found for concrete not to improve apparently its tensile strength and fracture energy is recommended to be its appraisal parameter.

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

    OpenAIRE

    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...

  10. Study on the Dynamic Performance of Polypropylene Fiber Reinforced Concrete

    OpenAIRE

    Zhang Ying; Zheng Chunhang; Wu Rujun; Chen Xi; Guoping Jiang

    2013-01-01

    The dynamic performance of polypropylene fiber reinforced concrete is studied with the SHPB experiment. The relationship of the strain-stress curves are all obtained in the experiment. The crack characteristics of polypropylene reinforced concrete and plain concrete are also investigated. Analyzed the relation between the character on the crack surface of concrete and material properties and the impact pressure. Also the multi-fractal characteristics are given on the crack surface of concrete...

  11. CALCULATION ALGORITHM FOR CONCRETE LONGEVITY BY GENERALIZED CRITERION

    OpenAIRE

    S. N. Leonovich

    2014-01-01

    The paper describes problems pertaining to corrosion theory and forecast of reinforced concrete structure service life. The author considers that application of modern investigation methods on the basis of failure mechanics and analysis concrete porosity will make it possible to develop a general theory of concrete corrosion and calculation of reinforced concrete structure service life. Provision of the required longevity of reinforced concrete structures is not less important than the provis...

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

    OpenAIRE

    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...

  13. Capability of GGBS concrete exposed to sea water

    International Nuclear Information System (INIS)

    This paper reported studies the penetration of chloride into ground granulated blast furnace slag (GGBS) concrete with exposure on marine environment. Test were conducted on ordinary portland cement (OPC) concrete and 60% (by weight) of OPC replaced GGBS (S-60). The specimens immersed in sea water were tested for chloride penetration. The results show that higher replacement level of GGBS in concrete significantly reduce the chloride content in concrete. The results also show that chloride concentration decreases with increasing depth into concrete. (author)

  14. Transfer and anchorage bond behaviour in self-compacting concrete

    OpenAIRE

    Rigueira-Víctor, J. W.; Arbeláez, C. A.; Serna-Ros, P.; Martí-Vargas, J. R.

    2006-01-01

    Self-compacting concretes (SCC) provide solutions to the problems facing precast concrete construction, enhancing competitiveness, reducing turnaround times and improving final product quality. SCC is fast becoming a key product for the future development of the precast pre-stressed concrete industry.The present paper compares the bond performance of SCC and traditional concrete (TC). The bond performance results confirm the viability of SCC in precast pre-stressed concrete manufacture, despi...

  15. Experimental Studies on Impact Characteristics of Steel Fibre Reinforced Concretes

    OpenAIRE

    K. Anbuvelan

    2014-01-01

    Research work carried out so far towards the development of concrete that exhibits improved impact resistance than conventional concrete. There are several situations in which concrete structural elements are subjected to impact loading. The behaviour of concrete under impact loads is far from adequate and there is significant variability in the published literature. The primary reason for this is the lack of a standardized technique of testing concrete under impact. In this project, an attem...

  16. Modelling of the fracture toughness anisotropy in fiber reinforced concrete

    OpenAIRE

    Tarasovs, S.; J. Krūmiņš; V. Tamužs

    2016-01-01

    Steel fiber reinforced concrete is potentially very promising material with unique properties, which currently is widely used in some applications, such as floors and concrete pavements. However, lack of robust and reliable models of fiber reinforced concrete fracture limits its application as structural material. In this work a numerical model is proposed for predicting the crack growth in fiber reinforced concrete. The mixing of the steel fibers with the concrete usually creates...

  17. US Patent: Method of manufacture of a composite concrete article

    OpenAIRE

    Morrow, Ruth; Belford, Patricia

    2014-01-01

    A method of manufacturing a composite concrete article comprising forming a textile structure, removing material from regions of the textile structure to create voids in the textile structure and incorporating the textile structure into a body of wet uncured concrete such that the concrete flows into the voids created in the textile structure, embedding the textile structure into the concrete, whereby the textile structure defines at least a portion of a surface of the cured concrete article.

  18. Concreting method that produce high modulus of elasticity

    OpenAIRE

    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...

  19. Some Properties of Fiber Reinforced Self Compacting Concrete

    OpenAIRE

    Eren, Özgür; Alyousif, Ashraf

    2010-01-01

    Today many countries are producing self-compacting concrete (SCC) and it is known that SCC has many advantages compared to conventional concrete. On the other hand, it is very well known that tensile strength of concrete can be improved by adding steel fibers in concrete. Although fiber reinforced concrete (FRC) is being produced in Cyprus for a long time, SCC is a new product for construction industry. Therefore, combination of SCC & FRC would bring many benefits. This study was split in...

  20. Analysis of production factors in high performance concrete

    OpenAIRE

    Gilberto Carbonari; Ravindra Gettu; Luiz Agullo; Berenice Martins Toralles Carbonari

    2003-01-01

    The incorporation of silica fume and superplasticizers in high strength and high performance concrete, along with a low water-cement ratio, leads to significant changes in the workability and the energy needed to homogenize and compact the concrete. Moreover, several aspects of concrete production that are not critical for conventional concrete are important for high strength concrete. This paper will discuss the need for controlling the humidity of the aggregates, optimizing the mixing seque...

  1. HIGH PERFORMANCE CONCRETE WITH GGBS AND ROBO SAND

    OpenAIRE

    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 ...

  2. Design of ecological concrete by particle packing optimization

    OpenAIRE

    Fennis, S.A.A.M.

    2011-01-01

    The goal of this research project on Ecological Concrete was to reduce the CO2-emission of concrete and to reuse secondary materials form concrete production and other industries simultaneously. This also minimizes the use of natural resources and the production costs. To replace cement in concrete in a safe way, the main question answered in this thesis was how particle packing models can be used to predict the mechanical properties of ecological concrete from its basic components. To optimi...

  3. Study of concrete deterioration thirough its microstructure

    OpenAIRE

    Ribas Silva, Moema

    1993-01-01

    The observed morphologies in concrete microstructure indicates a microbiological deterioration of the material. Some hypothesis are suggested, for the presence of the microorganisms in concrete. Its microstructure has been analysed through specified techniques and some microphotos of the observed morphologies and deterioration products are shown in this work.

    Las morfologías observadas en la microestructura del hormigón indican una degradación microbiológica del material. A...

  4. Utilization of Electronic Waste Plastic in Concrete

    Directory of Open Access Journals (Sweden)

    Vivek S. Damal

    2015-04-01

    Full Text Available In India, bitumen pavements are commonly used for highways. Due to the increasing traffic intensity, distress such as rutting and cracking of pavements are very common in Indian roads. Under varying seasonal temperature, flexible pavements tend to become soft in summer and brittle in winter. Investigations revealed that properties of concrete can be better than bitumen roads. But now a day‟s concrete roads are used commonly because concrete roads have more life span than the bitumen roads. In large cities now a day‟s concrete roads are used because concrete roads are more durable, strengthen and having more life span than bitumen roads. Waste plastics and E-waste (electronic waste both by domestic and industrial sectors can be used in the production of asphalt mix. Waste plastic, mainly used for packing are made up of polyethylene, polypropylene, polystyrene. Electronic waste, abbreviated as e-waste, consists of discarded old computers, TVs, refrigerators; radios, etc are basically any electrical or electronic appliance that has reached its end of life. An experimental study is made on the utilization of E-waste particles as fine aggregates in concrete with a percentage replacement ranging from 0 % to 21.5% i.e. (7.5%, 15% and 21.5% on the strength criteria of M30 Concrete. Compressive strength Concrete with and without E- waste plastic as aggregates was observed which exhibits a good strength. The feasibility of utilizing E-waste plastic particles as partial replacement of fine aggregate has been presented. In the present study, compressive strength was investigated for Optimum Cement Content and 7.5% E-plastic content in mix yielded stability and very good in compressive strength of 43 grade cement.

  5. Design Methods for Fibre Reinforced Concrete

    DEFF Research Database (Denmark)

    Stang, Henrik

    The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil.......The present paper describes the outline of a research project on Fibre Reinforced Concrete (FRC) currently being carried out in Denmark under the supervision of Danish Council of Technology, Danish Technical Research Council and Danish Natural Science Research Counsil....

  6. Mechanical Properties of Plastic Concrete Containing Bentonite

    OpenAIRE

    Peng Zhang; Qiaoyan Guan; Qingfu Li

    2013-01-01

    Plastic concrete consists of aggregates, cement, water and bentonite, mixed at a high water cement ratio, to produce a ductile material. It is used for creating an impermeable barrier (cut-off wall) for containment of contaminated sites or seepage control in highly permeable dam foundations. The effects of water to binder ratio and clay dosage on mechanical properties of plastic concrete were investigated. The results indicate that the water to binder ratio and clay dosage have great influenc...

  7. Self-sensing concrete with nanomaterials

    OpenAIRE

    Chen, Z; Ding, Y; Torgal, Fernando Pacheco; Zhang, Y.

    2013-01-01

    Conductive concrete containing nano carbon black (NCB) and carbon fibre (CF) to enable the self-diagnosis of strain and damage was studied. The effect of NCB and CF on workability, mechanical properties and fractional change in resistance (FCR) in fresh and hardened concrete was analysed. The relationship between the FCR, the strain of initial geometrical neutral axis (IGNA) and the degree of beam damage was established. The results showed that the relationship between the FCR and the IGNA st...

  8. Measurement of neutron activation in concrete samples

    International Nuclear Information System (INIS)

    The results of activation studies of ordinary and barytes concrete samples relevant for research reactor decommissioning are given. Five important long-lived radioactive isotopes (54Mn, 60Co, 65Zn, 133Ba, and 152Eu) were identified from the gamma-ray spectra measured in the irradiated concrete samples. Activation of these samples was also calculated using ORIGEN2 code. Comparison of calculated and measured results is given. (author)

  9. Variability in properties of Salado Mass Concrete

    International Nuclear Information System (INIS)

    Salado Mass Concrete (SMC) has been developed for use as a seal component in the Waste Isolation Pilot Plant. This concrete is intended to be mixed from pre-bagged materials, have an initial slump of 10 in., and remain pumpable and placeable for two hours after mixing. It is a mass concrete because it will be placed in monoliths large enough that the heat generated during cement hydration has the potential to cause thermal expansion and subsequent cracking, a phenomenon to avoid in the seal system. This report describes effects on concrete properties of changes in ratio of water to cement, batch size, and variations in characteristics of different lots of individual components of the concrete. The research demonstrates that the concrete can be prepared from laboratory-batched or pre-bagged dry materials in batches from 1.5 ft3 to 5.0 yd3, with no chemical admixtures other than the sodium chloride added to improve bonding with the host rock, at a water-to-cement ratio ranging from 0.36 to 0.42. All batches prepared according to established procedures had adequate workability for at least 1.5 hours, and achieved or exceeded the target compressive strength of 4500 psi at 180 days after casting. Portland cement and fly ash from different lots or sources did not have a measurable effect on concrete properties, but variations in a shrinkage-compensating cement used as a component of the concrete did appear to affect workability. A low initial temperature and the water-reducing and set-retarding functions of the salt are critical to meeting target properties

  10. Durability Environmental Regionalization for Concrete Structures

    OpenAIRE

    Daming Luo; Yan Wang; Ditao Niu

    2013-01-01

    Environment is the external factor that affects the durability of concrete structures. Buildings in different regions with different climates will respond to durability deterioration in different ways. For macroenvironmental regionalization, the dominant factor analysis method of the climatic zonation was applied into the environmental regionalization in this paper. Based on the environmental characteristics in China and the effect of environmental factor on the durability of concrete structu...

  11. An ultrasound monitoring system for concrete structures

    OpenAIRE

    Wolf, Julia; Mielentz, Frank; Milmann, Boris; Helmerich, Rosemarie; Wiggenhauser, Herbert; Kurz, Jochen Horst; Moryson, Ralf M.; Samokrutov, Andrey; Alekhin, Sergey; Alver, Ninel

    2014-01-01

    The research project "Ultrasonic Net for Concrete Monitoring (UNeCOM)" aims at developing a methodology for an embedded ultrasonic network for the condition assessment of infrastructure constructions. Civil engineering structures made of concrete, which are located in tectonically active regions or undergo special loading conditions, may require continuous monitoring. It is important to assess the condition of the building and its stability to recognise and classify the effect of a seismic ev...

  12. Strain rate effects for spallation of concrete

    Directory of Open Access Journals (Sweden)

    Häussler-Combe Ulrich

    2015-01-01

    Full Text Available Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property – which can be covered by rate dependent stress strain relations – or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

  13. Porous concrete mixtures for pervious urban pavements

    OpenAIRE

    Castro, J.; Fernández, B.; Videla, C.; de Solminihac, H.

    2007-01-01

    The present study aimed to analyze the hydraulic and mechanical behaviour of a series of roller-compacted, laboratory porous concrete mixtures. The mix design variables examined were the actual void ratio in the hardened concrete and the water/cement ratio. From these results the better dosages from the mechanical and hydraulical behaviour point of view were determined. One of the designs developed was found to exhibit excellent hydraulic capacity and 20% greater strength than the mixtures re...

  14. Humidity measurements in the precast concrete

    International Nuclear Information System (INIS)

    The precast concrete industry manufactures requires a good knowledge and control of the humidity factor: during the manufacturing process, in order to regulate the water content of aggregates, or the fresh concrete workability: during the quality control of the product characteristics. The principles of measurements: conductivity, dielectric characteristics and neutron moisture meters are compared for cost, humidity range, accuracy, temperature dependence, interfering elements, density dependence, grain size and shape

  15. Bacteria-based self-healing concrete

    OpenAIRE

    Jonkers, H.M.

    2011-01-01

    A typical durability-related phenomenon in many concrete constructions is crack formation. While larger cracks hamper structural integrity, also smaller sub-millimeter sized cracks may result in durability problems as particularly connected cracks increase matrix permeability. Ingress water and chemicals can cause premature matrix degradation and corrosion of embedded steel reinforcement. As regular manual maintenance and repair of concrete constructions is costly and in some cases not at all...

  16. Seismic analysis of infilled reinforced concrete frames

    OpenAIRE

    Novak, Luka

    2013-01-01

    The effect of masonry infills on seismic behaviour of reinforced concrete frames is described. In the first part of the thesis, the theoretical background and procedure for seismic analysis of such structures according to Eurocode 8 are presented. The effect of masonry infill was demonstrated by means of an example of four-storey reinforced-concrete building, including the consideration of the effect of soft storey mechanism. All linear elastic analyses were performed with ETABS software. The...

  17. Monitoring the durability of marine concrete structures

    OpenAIRE

    Tzoura, Effrosyni; Basheer, Muhammed; Nanukuttan, Sreejith; McPolin, Daniel; McCarter, John; Grattan, Kenneth; Sun, Tong; Srinivasan, Sudarsan

    2016-01-01

    New techniques based on embedded sensors have been developed for monitoring reinforced concrete structures for assessing their durability, which can be used instead of the conventional non-destructive test techniques. The continuous monitoring of concrete for its durability with various types of sensors allows not only early assessment of the potential durability of structures, but also a prediction of their service life. Effrosyni Tzoura and Muhammed Basheer of University of Leeds, Sreejith ...

  18. Civil engineering: EDF needs for concrete modelling

    International Nuclear Information System (INIS)

    Concrete structures which are encountered at EDF, like all civil engineering structures, age. In order to adapt the maintenance conditions of these structures, particularly to extend their service life, and also to prepare constructions of future structures, tools for predicting the behaviour of these structures in their environment should be available. For EDF the technical risks are high and consequently very appropriate R and D actions are required. In this context the Direction des Etudes et Recherches (DER) has developed a methodology for analysing concrete structure behaviour modelling. This approach has several aims: - making a distinction between the problems which refer to the existing models and those which require R and D; - displaying disciplinary links between different problems encountered on EDF structures (non-linear mechanical, chemical - hydraulic - mechanical coupling, etc); - listing of the existing tools and positioning the DER 'Aster' finite element code among them. This document is a state of the art of scientific knowledge intended to shed light on the fields in which one should be involved when there is, on one part a strong requirement on the side of structure operators, and on the other one, the present tools do not allow this requirement to be satisfactorily met. The analysis has been done on 12 scientific subjects: 1) Hydration of concrete at early ages: exothermicity, hardening, autogenous shrinkage; 2) Drying and drying shrinkage; 3) Alkali-silica reaction and bulky stage formation; 4) Long term deterioration by leaching; 5) Ionic diffusion and associated attacks: the chlorides case; 6) Permeability / tightness of concrete; 7) Concretes -nonlinear behaviour and cracking (I): contribution of the plasticity models; 8) Concretes - nonlinear behaviour and cracking (II): contribution of the damage models; 9) Concretes - nonlinear behaviour and cracking (III): the contribution of the probabilistic analysis model; 10) Delayed behaviour of

  19. COMPRESSIVE STRENGTH CHARACTERISTICS OF TILE WASTE CONCRETE

    OpenAIRE

    Ofonime A. Harry*, Ifiok E. Ekop

    2016-01-01

    Increase in the use of concrete in construction industry in Nigeria has led to the rise in the cost of its constituent material. This has necessitated research into the use of alternative material which is cheaper and can produce a comparable level of strength as the conventionally used ones. This paper present the results of an investigation into the compressive strength characteristics of concrete made with ceramic tile waste as coarse aggregates. The percentage of tile waste was varied in ...

  20. Commingling Yarns for Reinforcement of Concrete

    OpenAIRE

    Kravaev, Plamen; Janetzko, Steffen; Gries, Thomas; Kang, Bong-Gu; Brameshuber, Wolfgang; Zell, Maike; Hegger, Josef

    2009-01-01

    Textile reinforced concrete (TRC) is an innovative composite material, which is being intensely and practice-oriented investigated on national and international level. In the last few years this material has gained increasing importance in the field of civil engineering. In the context of the collaborative research project SFB 532 at the RWTH Aachen University, research was carried out to understand and to predict the behaviour of different yarn structures in fine grained concrete. Based on t...