Bibliografías temáticas / Concrete admixture

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Literatura académica sobre el tema "Concrete admixture"

Autor: Grafiati
Publicado: 4 de junio de 2021
Última modificación: 1 de febrero de 2022

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Artículos de revistas sobre el tema "Concrete admixture"

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Agbi, G. G., O. Z. Tachere y H. O. Juwah. "Evaluation of the impact of chemical admixtures on the compressive strength properties of concrete". Applied Journal of Physical Science 3, n.º 1 (30 de abril de 2021): 72–80. http://dx.doi.org/10.31248/ajps2021.051.

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This study was carried out to evaluate the effect of chemical admixtures on the compressive strength of concretes. The concretes were produced with the concrete mix ratio of 1:2:4, while water to cement (w/c) ratios of 0.35, 0.4, 0.45, 0.5 and 0.55 were adopted. Different concrete mixtures were produced using two chemical admixtures (hydroxycarboxylic acid and MasterRheobuild 1100) applied at the rate of 1.3% (weight of the cement), during the production process. Laboratory results of the fine aggregate used for the concrete production showed that it was well graded met international standards. All the concretes were produced and tested in accordance to American Society for Testing and Materials (ASTM) standard procedures. Results indicated that the concrete produced with the chemical admixtures showed better concrete performances both in the fresh and hardened state. After 28 days of casting, concrete produced with MasterRheobuild 1100 admixture had the best compressive strength (32 MPa); compared with the compressive strength of the concrete produced with the hydroxycarboxylic acid admixture (28 MPa), and the control concrete samples that had compressive strength of 25 MPa. In addition, the fresh concrete produced with chemical admixtures gave a better slump than the fresh concrete produced without any chemical admixture. Likewise, hydroxycarboxylic acid admixture performs better among the two admixtures used, given a more linear relationship between the slump and water/cement ratio. These results showed the importance of chemical admixtures when higher compressive strength becomes a vital factor in structural constructions
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Xie, Jian Bin, Tian Chun He, Yong Ping Ai y Guo Jin Ji. "Study on the Properties of Mass Hydraulic Concrete with Admixtures of Limestone Powder and Water Quenched Iron Slag". Advanced Materials Research 255-260 (mayo de 2011): 3573–78. http://dx.doi.org/10.4028/www.scientific.net/amr.255-260.3573.

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For mass concrete with the admixtures of limestone powder and water quenched iron slag (shortly called double admixture concrete) in dam of Jinghong hydropower station located at the downstream of Lancang river in Yunnan province, the mineral composition of double admixture was analyzed in this paper. And it is also studied by materials testing and microscopic analysis methods such as laser particle analysis, scanning electron microscopy, energy spectrum analysis, X-ray diffraction analysis and thermo gravimetric-differential thermal analysis that the hydration, hydrated product and mechanism of hydration process in the system of cementing and double admixture material system. Then the mechanical, thermal and deformation properties and the durability of the concrete with double admixtures were also analyzed by experimental methods. The study results show it was theoretically feasible that adopting the double admixtures as the admixture of the mass hydraulic concrete which can be roller compacted concrete or normal concrete. And the properties of the double admixture concrete in Jinghong hydropower station meet all kind requirements.
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Gadgihalli, Vishal, Ramya, Abrar Khan, Raghavendra Prasad Dinakar y Babitha Rani. "ANALYSIS OF PROPERTIES OF CONCRETE USING HUMAN HAIR LENGTH GREATER THAN 10CENTIMETER DIPPED IN SALT WATER AS FIBER REINFORCEMNT ADMIXTURE". International Journal of Research -GRANTHAALAYAH 5, n.º 4RASM (30 de abril de 2017): 50–53. http://dx.doi.org/10.29121/granthaalayah.v5.i4rasm.2017.3368.

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Admixtures now days play a predominant role in concrete manufacturing. The admixtures ranged from blood in history to fiber reinforcement admixture. In this paper the author analyzing the properties of concrete using salt water cured and oven dried human hair whose length exceeding 10cm as fiber reinforced admixture is studied and verified by strength of ordinary Portland cement without using any admixture. Using human hair length greater than 10cm as fiber reinforcement admixture gave good percentage of increment in compressive strength and flexural strength, but as the length of the human hair increases used for concrete as fiber reinforcement admixture reduces the strength.
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4

Pazderka, Jiří. "The Crystalline Admixture Effect on Concrete and Cement Mortar Compressive Strength". Key Engineering Materials 722 (diciembre de 2016): 87–91. http://dx.doi.org/10.4028/www.scientific.net/kem.722.87.

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There have been many experimental measurements of the waterproofing ability of concrete with a crystalline admixture. For the comprehensive evaluation of crystalline admixtures, it is necessary to consider their effect on the compressive strength of concrete fck, not only their waterproofing ability. The paper describes laboratory testing which subject was the selected crystalline admixtures effect on the compressive strength of concrete fck. The results have shown that the compressive strength fck,cubeof concrete with a crystalline admixture (added in an amount of 2%) was almost identical to the specimens from concrete without admixture after 28 days. The compressive strength of the next specimens from cement mortar with a smaller amount of a crystalline admixture (1%) after the 28 days was higher than the strength of the specimens without admixtures.
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Stehlík, Michal. "ENHANCING THE DURABILITY OF CONCRETE MADE OF CONCRETE RECYCLATE BY ADDITIVES AND ADMIXTURES". JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 20, n.º 2 (10 de marzo de 2014): 270–79. http://dx.doi.org/10.3846/13923730.2013.802708.

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The aim of this research is to find an optimum combination of silicate admixtures and epoxy dispersion additives which would positively influence the durability and mechanical properties of concretes made of concrete recyclate. The durability of concrete is dependent on its cover layer permeability and also on the overall permeability of concrete recyclate. The cover layer permeability was evaluated by means of three methods, namely the air permeability method TPT and two methods of measuring water permeability, GWT and ISAT. Fine silicate admixtures and dispersion additives influence the air and water permeability of concrete made of concrete recyclate in different ways. The dose of 10% of microsilica or 30% of slag or fly ash decreases the air permeability of concrete. Water permeability, on the other hand, is decreased by adding a dose of 12% of pure epoxy dispersion. As regards improving the mechanical properties of concrete made of concrete recyclate, it seems to be promising to use a combination of 30% of slag admixture or 10% of microsilica admixture with 12% of epoxy dispersion additive. However, the price of admixtures and additives is relatively high. That is why additive enhanced concretes made of concrete recyclate are intended for special purposes.
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Luo, Mei Fang. "Study on Effects of Concrete Admixtures on Performance of Concrete". Applied Mechanics and Materials 94-96 (septiembre de 2011): 856–59. http://dx.doi.org/10.4028/www.scientific.net/amm.94-96.856.

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Concrete admixture is a kind of addition agents, which can improve the performance of concrete. Adding a certain amount of concrete admixture can enhance the early strength, the age strength, and the anti-permeability strength of concrete. Also, concrete admixtures can improve the workability and adjust the setting time of concrete, so as to reduce the dosage of concrete and save the cost of concrete. This paper describes the types of concrete admixture and their functions, studies the functions of water reducers, and analyzes their effects to concrete, so as to improve the concrete performance and save materials in actual operation.
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Wang, Xue Fang y Jian Lan Zheng. "Influence of Compounded Mineral Admixtures on Shrinkage and Early-Age Cracking Behaviors of Concrete". Advanced Materials Research 450-451 (enero de 2012): 738–42. http://dx.doi.org/10.4028/www.scientific.net/amr.450-451.738.

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Influence of compounded mineral admixtures on shrinkage and early-age cracking behaviors of concrete was studied, based on the fellow factors: fly ash to blast furnace slag(denoted as BSF) ratio, fly ash-metakaolin ratio, BSF-silica fume ratio. Research shows that the Pozzolanic admixtures compounded with cementitious admixtures have complementary and synergistic effect for hydration progress of concrete, which can enhance the volume stability and cracking behaviors of concrete. However, the pozzolanic admixture compounded with other pozzolanic admixture, two pozzolanic admixtures will grab Ca(OH)2 resource. And then if the dosage of mineral admixture is higher, the compounding will result to decrease the volume stability and cracking behaviors of concrete.
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8

Zheng, Yu Xian y Xun Guo Zhu. "The Influence on the Concrete Durability in Bleed Air Performance Caused by Concrete Admixture". Advanced Materials Research 690-693 (mayo de 2013): 767–70. http://dx.doi.org/10.4028/www.scientific.net/amr.690-693.767.

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The article issued the influence on concrete durability caused by concrete admixture, based on the further study on concrete admixture bleed air performance test, and researched the influence on concrete durability caused by it. The experiments show that the admixtures of air-entraining performance improve internal pore structure of concrete and increase the compacting condition concrete. Concrete admixture also can improve the impermeability of concrete frost resistance and improve the resistance to environmental actions, and proposed concrete air content of the Dalian region suitable value.
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Al-obaidey, Shubbar Jawad. "The Synergic Effects of Mineral Admixtures in Ternary Blended Cement: A Review". Journal of Engineering 27, n.º 2 (1 de febrero de 2021): 83–105. http://dx.doi.org/10.31026/j.eng.2021.02.07.

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In the last decades, using mineral admixture in concrete became very necessary to improve concrete properties and reduce CO2 emissions associated with the cement production process. Subsequently, more sustainable concrete can be obtained. Ternary blended cement containing two different types of mineral admixture can achieve ambitious steps in this trend. In this research, the synergic effects of mineral admixtures in ternary blended cement and its effects on concrete fresh properties, strength, durability, and efficiency factors of mineral admixture in ternary blended cement, were reviewed. The main conclusion reached after reviewing many literature pieces is that the concrete with ternary blended cement, depending on types of mineral admixtures used, replacement percentages by weight of cement, and age of concrete, exhibited superior properties than with no mineral admixtures and corresponding binary blended cement concrete.
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Zhao, Mei Li. "The Effects of Mineral Admixture on the Compressive Strength of Concrete". Advanced Materials Research 450-451 (enero de 2012): 263–66. http://dx.doi.org/10.4028/www.scientific.net/amr.450-451.263.

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Mineral admixture was one or more industrial waste, or mixed with finely ground natural minerals, or grinded mixture.By replacing part of the cement with mineral admixtures , cement could be saved and improved the performance of concrete. In this paper，the compressive strength and slump of the concrete with mineral admixture were tested. The amount of cement replaced by mineral admixture in the concrete affected the compressive strength and the slump. According to the compressive strength and slump of the concrete, the optimum dosage of the mineral admixture was from 30% to 40%.
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Tesis sobre el tema "Concrete admixture"

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Millard, Marcus J. "Effects of Lithium Nitrate Admixture on Early Age Concrete Behavior". Thesis, Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/11615.

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Alkali silica reaction (ASR), a reaction which occurs between reactive siliceous mineral components in the aggregate and the alkaline pore solution in concrete, is responsible for substantial damage to concrete structures in the U. S. and across the world. Lithium admixtures, including lithium nitrate (LiNO3), have been demonstrated to mitigate ASR damage, and are of particular interest for use in concrete airfield pavement construction, where ASR damage has been recently linked to the use of certain de-icing chemicals. Although the effectiveness of lithium admixtures at ASR-mitigation is well-researched, relatively less is known regarding the potential effects, including negative effects, on overall concrete behavior. The goal of this research is to better understand the influence of LiNO3 admixture on early age concrete behavior, and to determine if a maximum dosage rate for its use exists. Isothermal calorimetry, rheology and bleed water testing, time of setting, chemical shrinkage, autogenous shrinkage, free and restrained concrete shrinkage, and compressive and flexural strength were measured for pastes and concretes prepared with a range of LiNO3 dosages (i.e., 0, 50, 100, 200, and 400% of the recommended dosage). In addition, the interaction of LiNO3 with cement was evaluated by comparing results obtained with six cements of varying alkali and tricalcium aluminate (C3A) contents. Additionally, one of these cements, was examined alone and with 20% by weight Class F fly ash replacement. Results indicate that the hydration of the tricalcium silicate and tricalcium aluminate components of cement are accelerated by the use of LiNO3, and that low alkali cements (typically specified to avoid damage by ASR) may be particularly susceptible to this acceleration. However, inclusion of Class F fly ash at 20% by weight replacement of cement (also common in applications where ASR is a concern) appears to diminish these possibly negative effects of LiNO3 on early age hydration acceleration and heat generation. Dosages higher than the current standard dosage of LiNO3 may have minor effects on fresh concrete workability, causing slight decreases in Bingham yield stress, corresponding to slightly higher slump. Fresh concrete viscosity may also be affected, though more research is necessary to confirm this effect. LiNO3 had no effect on quantity of bleed water in the mixes tested. Generally, LiNO3 had no effect on initial and final setting times, although increasing dosages caused faster set times in the lowest alkali (Na2Oeq = 0.295%) cement examined. In shrinkage testing, higher LiNO3 dosages appeared to cause initial expansion in some sealed paste specimens, but in all cases the highest dosage led to greater autogenous shrinkage after 40 days. In concrete specimens, however, the restraining effect of aggregates diminished shrinkage, and no effect of the LiNO3 was apparent. In no cases, with any dosage of lithium tested, with or without fly ash replacement, did restrained shrinkage specimens show any cracking. Strength testing produced mixed results, with laboratory specimens increasing in 28-day compressive strength, but companion specimens cast in the field and tested by an outside laboratory, exhibited lower 28-day compressive strength, with increasing lithium dosages. Flexural specimens, also cast in the field and tested by an outside laboratory, appeared to show an increase in 28-day flexural strength with increasing lithium dosages. However, because of the conflicting results when comparing the various strength data, further research is necessary for conclusive evidence of LiNO3 effects on concrete strength.
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2

SULAIMAN, SALMAN OLUWATOYIN. "FREEZE-THAW DURABILITY OF CONCRETE WITH NATURAL AND RECYCLED CONCRETE AGGREGATES USING AIR ENTRAINING ADMIXTURE". OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/1864.

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Freezing and thawing cycles is one of the most damaging factors that affect the durability of concrete. The damages caused by the cyclic freeze-thaw action can be divided into two factors. The first factor is an increase in internal crack, which causes the loss in relative dynamic modulus (RDM) of the concrete and the second factor is surface scaling, which leads to weight loss of the concrete. In this study, the durability of concrete made by replacing natural coarse aggregates (NCA) with various percentages of recycled concrete aggregates (RCA). Also some tests have been conducted with the addition of air entraining admixture (AEA). Prior to mixing the concrete, both NCA and RCA were characterized to determine their suitability as a construction material. Concrete mixes consisting of 0, 20, 40, 60, 80, and 100% replacement (by weight) of NCA with RCA were prepared. The same concrete mixes were prepared again but with the addition of an air entraining admixtures (AEA). All specimens were tested for compressive strength after a curing period of 7, 14, and 28 days. The compressive strength of the concrete made with different percentage of RCA decreases as the percentage of RCA increases. After 28 days of curing, samples with 0, 40, and 100% replacement of NCA with RCA were placed in the freeze-thaw chamber along with 0, 20, 40, 60, 80, and 100% NCA replacement containing AEA. After several cycles of freezing and thawing; the RDM, change in weight and change in length were measured. In this study loss of RDM and weight loss were noticed, as the cyclic freeze-thaw increases. It has also been observed that concrete mixes containing AEA were still durable after 300 cycles of freezing and thawing; however, the specimens without AEA failed before 150 cycles.
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Tatli, Emre. "Pretreatment Of Peanut Shells For Co-production Of Glucose And Concrete Admixture". Master's thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615535/index.pdf.

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This thesis work aims the ionic liquid pretreatment of peanut shells for co-production of glucose as fermentable sugar and lignin, considering a multi product perspective. The effects of ionic liquid type and pretreatment time period on the sugar and lignin yields were investigated, as the particle size and temperature parameters were determined in the preliminary studies. Peanut shells were pretreated at constant temperature, 150 oC, for 5, 15 and 30 minutes with 1-ethyl-3-methylimidazolium acetate and for 15, 30 and 60 minutes with 1-ethyl-3-methylimidazolium chloride. The pretreated peanut shells were then subjected to enzymatic hydrolysis in order to produce fermentable sugars, mostly, glucose. The solid residue obtained upon enzymatic hydrolysis was analyzed in terms of lignin quantity. 1-ethyl-3-methylimidazolium acetate pretreatment for 15 minutes resulted in the maximum reducing sugar and lignin yields
28 g of reducing sugar and 20 g of solid residue with 70% lignin were obtained per 100 g of peanut shells. Higher pretreatment time resulted in lower yields. Moreover, no optimal time period for 1-ethyl-3- methylimidazolium chloride pretreatment was obtained, since reducing sugar and lignin yields increased as the time period increased. Also all reducing sugar and lignin yields were lower than that obtained with 1-ethyl-3-methylimidazolium acetate. Lignin obtained upon enzymatic hydrolysis of 1-ethyl-3-methylimidazolium acetate pretreated peanut shells were characterized by SEM, FTIR, TGA and XRD analyses, which also showed the morphological and structural effects of pretreatment and enzymatic hydrolysis on peanut shells
and used as concrete admixture, which increased the flow of the concrete by 6%.
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Al, Menhosh A. A. A. Z. "An experimental study of high-performance concrete using metakaolin additive and polymer admixture". Thesis, University of Salford, 2018. http://usir.salford.ac.uk/45085/.

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In recent years, there has been a growing interest in the use of supplementary cementing materials and polymers to produce high-performance concrete. Utilizing a mineral substance as cement replacement in concrete has less environmental pollution and greatly increases the service life of the concrete structures due to improve the most of concrete properties in compared with conventional concrete. The aim of this project is an experimental study of high-performance concrete using metakaolin (MK) additive as partial replacement of cement and addition of the Styrene-Butadiene rubber (SBR) and Polyvinyl acetate (PVA), to conduct a novel research to investigate the effectiveness of the additives materials on the performance of concrete. It also investigates the effect of additional recycled plastic and glass fibre as reinforcements used in the modified concrete. Firstly, trial mixes of 460 cubes, 24 cylinders and 30 prisms were made to study the setting time, workability, mechanical properties and water absorption of the concrete to find the optimum metakaolin to cement ratio (MK/C), polymer to cement ratio (P/C), water to cement ratio (W/C), and the best curing method among the wet, dry and moist, respectively. The designed concrete mixes have a certain cement/sand/gravel proportion of 1:1.5:3. The trial mixtures were tested for setting time, slump of fresh concrete mix, mechanical properties, including compressive, splitting and flexural strength, and water absorption capacity at age up to 28 days. Three polymers to cement ratios, which are 2.5, 5 and 7.5%, and five metakaolin replacement ratio for the cement, which are 10, 15, 20, 30 and 40%, were studied, respectively. For these mixtures, five W/C ratios, which are 0.35, 0.38, 0.40, 0.45, and 0.50, respectively, were compared. The use of recycled plastic and glass fibre reinforcements took 5% of the total cement weight and tested for splitting and flexural strength testes. The first phase work has shown clear improvement of the performance of concrete modified by partial replacement of cement by metakaolin and adding polymers admixture together. The optimised mix was identified to be that of 5% added polymers included 80% SBR and 20% PVA, 15% metakaolin replacement for cement, 0.45 W/C ratio, and using limestone aggregate as a coarse aggregates and using moist curing method as a curing condition for the concrete. Secondly, the optimum mixture identified in the trial study was further investigated for its mechanical including compressive, flexural, and deformable proprieties at prolonged ages up to 545 days. In addition, a specific durability properties of concrete including water and gas permeability, carbonation penetration, chloride penetration, chemical attack resistance, water absorption, rate of water absorption and the corrosion rate of the steel reinforcement in the concrete. The results show that significant improvement in mechanical properties including compressive, splitting, flexural strength and deformation properties. Also, the results show improvement in durability properties including chemical resistance, water absorption, rate of water absorption, carbonation depth of penetration, chloride ion penetration, water penetration under pressure, water permeability, gas penetration and steel corrosion resistance. The optimum mix of 15% partial replacement of cement by metakaolin, 5% polymer, 0.45 W/C ratio and moist curing condition of the modified concrete produced high-performance concrete more environmental friendly due to improved overall of the mechanical and durability properties of the concrete. Finally, microscopic composition of the hydration products and the corresponding pores structure have been investigated for the optimised mixes based on the material composition analysis and microscopic images obtained using scanning electronic microscope (SEM) and the computed tomography scanner (CT) technologies. Correlation between the mechanical, durability properties and the microscopic phases has been investigated and discussed for a deep understanding of the mechanism of the optimum mixture. SEM and CT scanner technologies provide qualitative and quantitative description of the concrete properties. It’s also, proved that the concrete modified by both of metakaolin and two types of polymers have a significant change in the pores structure of concrete compared with other mixes. Scanning electron microscopy and computed tomography scanner results show that the approach can be effectively applied in high-performance concrete related studies and provide further evidence on mechanical and durability properties of concrete.
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5

Yazan, Kazim. "Effects Of Retempering With Superplasticizer On Properties Of Prolonged Mixed Mineral Admixture Containing Concrete At Hot Weather Conditions". Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/3/12606751/index.pdf.

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Concrete which is manufactured in a mixing plant to be delivered to construction site in unhardened and plastic stage is called ready-mixed concrete. Because of technical and economical reasons, many mineral and chemical admixtures are used in ready-mixed concrete production. As a result of extra mixing and delayed placing of ready-mixed concrete (especially at hot weather conditions), there can be many problems about concrete, like slump loss. Addition of water for retempering concrete is the usual procedure, but addition of water without proper adjustment in mixture proportions, adversely affects compressive strength. During this study, effects of prolonged mixing and retempering with superplasticizer on properties of fresh and hardened concrete at hot weather conditions are observed. Some of the properties of concrete inspected are compressive strength, splitting tensile strength, slump and air content. All mixes contain air entrainer and water reducer at a standard amount. The difference between mixes comes from kind and amount of mineral admixture which cement is replaced by. During the study, fly ash, blast furnace slag, ground clay brick and natural pozzolan are used at amounts, 25% and 50% of cement. Also, a mixture of pure cement is prepared as control concrete. 15 cm initial slump is planned in the experimental work. After five minutes and at the end of first, second, third and fourth hours of mixing process, if needed retempering process is proceeded with superplasticizer and samples are taken. As a result of retempering with superplasticizer, the aimed slump values are obtained. The effects are than, observed. As a result of this study, it has been observed that replacing Portland cement with certain mineral admixtures, especially fly ash at certain amounts, can be a solution for slump loss problem, by retarding the slump loss effect of prolonged mixing. Also it has been seen that ground clay brick causes better performance for slump values at lateral stages of mixing with respect to pure Portland cement. Another important observation has been about the increase in the amount of air caused by air entraining admixtures in fresh concrete based on prolonged mixing at hot weather conditions.
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Justice, Joy Melissa. "Evaluation of Metakaolins for Use as Supplementary Cementitious Materials". Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6936.

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Two metakaolins were evaluated for use as supplementary cementitious materials in cement-based systems. The metakaolins varied in their surface area (11.1 v. 25.4 m2/g), but were quite similar in mineralogical composition. Performance of metakaolin mixtures was compared to control mixtures and to mixtures incorporating silica fume as partial replacement for cement at water-to-cementitious materials ratios of 0.40, 0.50, and 0.60. In this study, the early age properties of fresh concrete and the mechanical and durability properties of hardened concrete were examined. Early age evaluations aimed to determine the reactivity of metakaolin (heat of hydration) and its effect on mixture workability (slump, setting time, unit weight). In addition, three types of shrinkage were monitored in metakaolin-cement systems: chemical, autogenous, and free. Compressive, tensile, and flexural strength and elastic modulus were measured at various concrete ages. The influence of metakaolin addition on durability was assessed through accelerated testing for sulfate resistance, expansion due to alkali-silica reaction, and through rapid chloride permeability measurements. To further quantify the underlying mechanisms of metakaolin's action, the microstructure of pastes was examined. Calcium hydroxide (CH) content was determined using thermogravimetric analysis and verified using differential thermal analysis. Surface area and pore size distribution were evaluated via nitrogen adsorption. These analyses yielded information about the pozzolanic reactivity of metakaolin, associated CH consumption and pore structure refinement, and resulting improvements in mechanical performance and durability of metakaolin-concretes.
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Adjoudj, Mhamed. "Effet des additions minérales et organiques sur le comportement rhéologique du béton". Thesis, Cergy-Pontoise, 2015. http://www.theses.fr/2015CERG0784/document.

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L'emploi de certaines additions minérales et organiques dans la confection du mortier et du béton contribue à une modification du processus d'hydratation du ciment. L'incorporation de ces additions minérales entraîne également une modification de la distribution granulaire, l'apparition de nouveaux sites de nucléation et une nouvelle activité des surfaces des grains. Ceci nécessite le malaxage avec des superplastifiants qui viennent défloculer les grains, libérer l'eau piégée dans les interstices et améliorer l'ouvrabilité du béton. Ces modifications des propriétés physicochimiques des composants du béton affectent directement les propriétés rhéologiques du mortier et du béton à l'état frais ainsi que ses composantes finales.L'objectif principal de ce travail est focalisé sur la prédiction des modifications rhéologiques apportées par les additions minérales aux mortiers afin de trouver les meilleures compositions d'une mise en œuvre convenable. Une étude expérimentale est entamée sur des mortiers normalisés où le ciment ordinaire est substitué partiellement par différentes additions minérales telles que la fumée de silice, le laitier des hauts fourneaux, la pouzzolane naturelle et le calcaire. Avec l'eau de gâchage, on a ajouté plusieurs types de superplastifiants avec différents dosages où les paramètres rhéologiques du mortier ont été mesurés respectivement par un mini cône et un rhéomètre.Les paramètre rhéologiques obtenus varient sensiblement avec chaque type d'addition minérale et dépendent de ses propriétés et son interaction avec le superplastifiant et les grains de ciment. Le superplastifiant à base de polycarboxylates est plus efficace en présence du ciment contenant du calcaire ou du laitier conduisant à une amélioration des propriétés rhéologiques. Par contre, le mortier devient plus visqueux s'il contient un fort pourcentage de pouzzolane naturelle. Une relation mathématique est proposée qui exprime la variation de chaque paramètre rhéologique selon le taux de substitution du ciment et le dosage en superplastifiant. Cette relation est exprimée par le produit de trois paramètres; l'effet de l'addition minérale, l'effet du superplastifiant et l'effet de leur interaction. Les coefficients de corrélation trouvés sont proches de l'unité et justifient bien la convenance de ce choix. L'application de cette nouvelle relation à d'autres résultats trouvés par d'autres chercheurs présente une grande satisfaction avec des résultats satisfaisant et des coefficients de corrélation allant 0,9 à 0,98
The use of some organic and inorganic admixtures in the production of mortar and concrete contributes to a change in the cement hydration process. The incorporation of these mineral additions also causes a change in the grain distribution, the appearance of new nucleation sites and a new activity of the grain surfaces. This requires mixing with superplasticizers which deflocculates grains, releases the trapped water in the interstices and improves the workability of concrete. These changes in the physicochemical properties of the cement paste directly affect the rheological properties of mortar and concrete in the fresh state and its final components.The main objective of this work is focused on the prediction of rheological changes of mineral additions mortars and finds the best composition for a suitable casting. An experimental study is underway on standardized mortars where ordinary cement is partially substituted by different mineral additions such as silica fume, blast furnace slag, natural pouzzolan and limestone powder. With the mixing water, was added several types with different dosages of superplasticizers where the rheological parameters of the mortar were measured respectively by a rheometer apparatus and a mini cone test.The Theological parameters obtained vary with each type of mineral addition and depend on its properties and its interaction with the superplasticizer and cement grains. The polycarboxylate superplasticizer is more effective in the presence of limestone powder or cement containing slag resulting in improved rheological properties. However, the mortar becomes more viscous if it contains a high percentage of natural pozzolan. A mathematical relationship is provided which expresses the variation of each rheological parameter according the substitution rate of the cement and superplasticizer dosage. This relationship is expressed by the product of three parameters; the effect of the mineral addition, the effect of the superplasticizer and the effect of their interaction. The correlation coefficients found are close to unity and well justify the appropriateness of this choice. The application of this new relationship to other results found by other researchers has high satisfaction with satisfactory results and correlation coefficients ranging from 0.9 to 0.98
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Islam, G. "Evaluating reactivity and sorptivity of fly ash for use in concrete construction". Thesis, University of Dundee, 2012. https://discovery.dundee.ac.uk/en/studentTheses/94122abd-aa82-4c91-85ea-079505e14489.

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This thesis describes research carried out to investigate techniques for (i) rapidly assessing the reactivity of fly ash; and (ii) evaluating its interaction with air-entraining admixtures (AEAs), both with regard to use in concrete. The materials considered for the project included, 54 fly ashes from 8 UK sources, and an additional three materials from Bangladesh, covering a range of fineness, loss-on-ignition (LOI) and production conditions (run-of-station, carbon removed, air-classified, co-combustion, oxy-fuel technology); Portland Cements (PCs) from five UK sources with various properties (strength classes 32.5 R, 42.5 N and 52.5 N); laboratory grade hydrated and quick limes; and three commercial AEAs and a standard laboratory grade reagent (surfactant). The research examining fly ash reactivity considered activity index tests to BS EN 450 (BSI, 2005c) as the reference and investigated tests covering fly ash properties/providing measures of fly ash behaviour to rapidly assess this. These included (i) fly ash fineness (45 µm sieve residue, or LASER particle size distribution (PSD) parameters), LOI and flow properties; (ii) accelerated curing of PC and lime-based mortars (iii) lime consumption by fly ash when combined with PC in paste or suspension (Frattini) or from a saturated lime solution; (iv) various measures of fly ash chemical composition (based on oxide/mineralogical analysis); and (v) a quicklime slaking test. The test results were validated by strength tests with 100 mm concrete cube. Results of the above indicated good correlations between fly ash fineness, mortar flow/water requirement and (pozzolanic) activity index (standard or accelerated curing). However, fly ash reactivity and fresh properties appeared to be influenced by the properties of the test PC (e.g. chemical composition and fineness) and there is a need to take this into account during assessment. Generally, finer fly ashes gave better flow; however, there is an optimum fineness (d90 ~40 µm) for best performance, and which is similar to the fineness of the test PC. Strong correlations between the accelerated and standard cured PC-based mortar indicate the latter can be used to estimate the former taking account of the fly ash properties. In view of eliminating the effect of PC properties on reactivity, mortar tests with laboratory grade hydrated lime suggested potential for this. However, for better assessment, this approach requires further work to address issues relating to slower rates of strength gain and increased time requirements, although high temperature conditions were used for curing. Measuring Ca(OH)2 consumption from fly ash/PC paste or suspension agreed with the behaviour in mortar, but needs special instruments (e.g. TGA or XRF). A similar approach with saturated lime did not work well, despite several measures being taken to try and improve this. The oxide and mineralogical analysis results of fly ash did not give good correlations with activity index, but improved when a factor combining them with fineness was considered. The test results were validated in concrete and with air-classified fly ashes from single sources which gave clear trend/behaviour. The lime slaking test was found to be ineffective for identifying fly ash reactivity. The reactivity assessment results were validated by carrying out concrete strength tests. In general, more consistent trends were obtained for fly ash from single source as noted with mortar earlier. Methods adopted/developed to assess the interaction of fly ash with AEA included (i) the foam index test; (ii) acid blue 80 (AB80) dye adsorption test (spectroscopic method); and (iii) methylene blue test. High variability in foam index test results between different operators were noted, which reflected differences in the degree of shaking applied and difficulties in identification of the test end point. Adoption of an automatic shaker and determination of suitable test conditions reduced this by more than 50%. Reliable test procedures were also established for the AB80 dye adsorption method. The results obtained from these tests gave very good correlations with fly ash specific surface area and the AEA dose required (both with commercial AEAs and standard reagent) for achieving target air contents in mortar and concrete. The methylene blue dye test also gave good correlations with these parameters, but was less effective for low LOI fly ashes. Between laboratory tests were carried out at three UKQAA members and considered, LOI, fineness (45 µm sieve and LASER PSD), and activity index. The results gave good agreement with those obtained at the Concrete Technology Unit for this work and again emphasized the role of fly ash fineness on its reactivity. Overall, fly ash fineness was found to be the best means of rapidly assessing its reactivity. Some of the other methods considered gave promising behaviour but require further refinements. Therefore, it is suggested that in addition to 45 µm sieve residue, other types of fineness measurement (e.g. sub 10 µm quantities, d50 and d90) can be considered suitable alternatives to activity index. Similarly, foam index tests with the automatic shaker or the AB80 test method could both be used as fly ash physical requirement tests, or in production control for air-entrained concrete.
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Láznička, Josef. "Studium vlivů ovlivňujících životnost cementobetonových krytů v ČR". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392354.

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This thesis deals with the study of cement – concrete coverings. The aim of the thesis is a summary of current knowledge of these constructions. The experimental part of this paper deals with the design of concrete for the lower layer of cement – concrete cover. Emphasis is placed on the elimination of microcracks and to increase the lifetime of these construction.
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Vieira, Flávio de Lima. "Estudo da viabilidade do resíduo proveniente das porcelanas de isoladores para utilização em concretos bombeáveis estruturais". Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/8131.

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This research aims to evaluate the tecniques for disposal of waste obtained from electrical insulators. These pieces are one of the supplies widely used for electric power generation, and become a waste due to their replacement for new ones after maintenance and expansion works, in places like substations, generating units, distribution networks, transmission lines and its own production process. In Brazil, it is possible to acumulate waste from these insulators in courtyards and waste areas, besides wastelands, impairing the environment. Thus, it is known that an alternative for treatment is needed and the lack of knowledge and techical safe forces the development of reasearches about this subject, what are still in the beggining. So, this study proposes the evaluation of potential use of such a porcelain in concrete, through the replacement of conventional aggregates and cement. The research was conducted with a careful characterization of the waste in different maximum dimension sizes, with physicochemical and mineralogical analysis obtained from X-Ray diffration and images from scanning eletronic microscopy, for example. Besides, tests of alkali-aggregate reaction were perfomed in order to assess the chemical stability of the waste in mortar. Regarding to viscoelastic and mechanical properties, the compressive strength, modulus of elasticity, water absorption, and abrasion/erosion were performed. The experimental program considered eleven different mixes of pumped concrete, take into account the following replacement rates: 8% replacement of cement; 50% and 100% replacement of fine aggregate; and 45% and 100% replacement of coarse aggregate. Some mixes were done with both replacement of fine and coarse aggregate. The investigation of mechanical strength, deformation and durability, in conditions aforementioned, demonstrates that concrete with replacement was statistically similar to concrete without any replacement by waste, resulting a suitable concrete with porcelain waste content. The efficiency of compressive strength ranged from 0,087 MPa/kg to 0,107 MPa/kg and the modulus of elasticity reached values up to 38 GPa, indicating expressive results for these properties. Lastly, in research is possible to observe the conclusions about reological characteristics of all concrete and the influence of these replacement on cement content.
A presente pesquisa aborda a temática da destinação do resíduo dos isoladores elétricos proveniente da cadeia geradora de energia elétrica, como as relacionadas às manutenções e ampliações das subestações, unidades geradoras, redes de distribuição, linhas de transmissão e do próprio processo de produção do isolador. No Brasil esta cadeia acumula progressivamente resíduos em pátios e áreas de descarte, e às vezes esses materiais são lançados por terceiros em locais como terrenos baldios, impactando no meio ambiente. Nesse contexto, uma alternativa seria sua utilização para outros fins, os quais, por falta de conhecimento e segurança técnica, ainda se encontram em fases iniciais de estudo. Diante disso, a presente pesquisa propõe a investigação do potencial de uso destas porcelanas no concreto, em substituição aos agregados convencionais e também ao cimento. Para tanto, conduziu-se incialmente uma caracterização minuciosa do resíduo nas suas diversas dimensões, por meio de análises químicas, físicas e mineralógicas utilizando diferentes métodos, como a difração de raios X e imagens por microscópico eletrônico de varredura, por exemplo. Na sequência foram realizados testes para verificar a estabilidade química do resíduo em argamassa para o desencadeamento de reações álcalis-agregado. Em relação à sua incorporação no concreto, foram realizados ensaios para aferição da resistência à compressão, módulo de elasticidade, absorção de água, abrasão e erosão. As análises foram realizadas em onze concretos estruturais bombeáveis com diferentes teores de substituição, que contemplaram adição de 8% em substituição ao cimento, no agregado miúdo com 50% e 100% de substituição, no agregado graúdo com 45% e 100%, e em algumas composições com substituições simultâneas no miúdo e graúdo. De posse dos resultados, foi traçado um perfil de resistência mecânica, deformabilidade e durabilidade que apresentaram para algumas substituições valores estatisticamente iguais ao concreto sem resíduo, tornando factível a utilização do concreto com porcelana. Eficiências para resistência à compressão variando de 0,087 MPa/kg a 0,107 MPa/kg, módulo de elasticidade com valores de até 38 GPa, são números significativos para as propriedades. Análises da reologia do concreto e impactos no consumo de cimento são aspectos também observados e discutidos no decorrer do trabalho.
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Libros sobre el tema "Concrete admixture"

1

Association, Cement Admixtures. Admixture data sheet: Quality assured admixtures. 9a ed. Kings Langley, Herts: Cement Admixtures Association, 1992.

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Korhonen, C. J. Freezing temperature protection admixture for Portland cement concrete. [Hanover, N.H.]: U.S. Army Cold Regions Research and Engineering Laboratory, 1996.

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Brooks, Eric W. Prestressed concrete bridge beams with microsilica admixture: Final report. Salem, Or: Oregon Dept. of Transportation, Research Unit, 1998.

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Lloyd, Christopher G. The effects of a calcium lignosulphonate admixture on concrete properties. Salford: University of Salford, 1986.

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Gao xing neng hun ning tu wai jia ji: High performance admixture for concrete. Beijing: Hua xue gong ye chu ban she, 2008.

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Dodson, Vance H. Concrete Admixtures. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4757-4843-7.

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Dodson, Vance H. Concrete admixtures. New York: Van Nostrand Reinhold, 1990.

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Hersch, Martin. Cement & concrete admixtures. Cleveland, Ohio: Freedonia Group, 1998.

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1938-, Mailvaganam N. P., ed. Chemical admixtures for concrete. 3a ed. New York: Routledge, 1999.

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Rixom, M. R. Chemical admixtures for concrete. 2a ed. London: E. & F.N. Spon, 1986.

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Capítulos de libros sobre el tema "Concrete admixture"

1

Munoz, Andrea, Sergio Cifuentes y Henry A. Colorado. "Admixture Optimization in Concrete Using Superplasticizers". En TMS 2018 147th Annual Meeting & Exhibition Supplemental Proceedings, 625–33. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-72526-0_59.

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Longhi, F. y F. Surico. "Effect of a Crystallizing Admixture on Concrete Properties: Italian Concrete Days". En Lecture Notes in Civil Engineering, 312–24. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-23748-6_24.

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Atienza, Jacki, John Fox y Charles Lanning. "Quantifying a Particulate-Based Admixture in Hardened Concrete". En Advances in Cement Analysis and Concrete Petrography, 161–71. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2016. http://dx.doi.org/10.1520/stp161320180001.

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Wang, Yuan y Bin Liu. "Study and Application of Salt-Scaling Resistant Admixture in Concrete". En Environmental Ecology and Technology of Concrete, 105–10. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-983-0.105.

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Dvorkin, Leonid, Vadim Zhitkovsky, Nataliya Lushnikova y Yuri Ribakov. "Metakaolin as Mineral Admixture for Cement-based Composites". En Metakaolin and Fly Ash as Mineral Admixtures for Concrete, 53–164. Boca Raton: CRC Press, 2021. http://dx.doi.org/10.1201/9781003096825-4.

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Hoang, Nguyen Ba, Pham Van Hung, Tran Viet Khanh y Nguyen Viet Huy. "Application of Asphalt Concrete using Limestone with Cement & Admixture". En Lecture Notes in Civil Engineering, 391–96. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-15-0802-8_60.

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Schwoon, Oliver. "A New Efficient and Safe Admixture for Freeze/Thaw Resistant Concrete". En High Tech Concrete: Where Technology and Engineering Meet, 2162–68. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-59471-2_247.

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Han, Jian Guo y Pei Yu Yan. "The Effect of Shrinkage-Reducing Admixture on Mechanical Properties and Volume Stability of Concrete". En Environmental Ecology and Technology of Concrete, 230–34. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-983-0.230.

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Moelich, Gerrit M., Rick van Huffel y Riaan Combrinck. "Used Oil as an Admixture to Improve the Rheological Properties of Concrete". En 3rd International Conference on the Application of Superabsorbent Polymers (SAP) and Other New Admixtures Towards Smart Concrete, 184–91. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-33342-3_20.

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Khode, Bhalchandra V. y Sujesh D. Ghodmare. "Effect of Mineral and Chemical Admixture for Improvement of High-Performance Concrete". En Smart Technologies for Energy, Environment and Sustainable Development, 417–25. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-6148-7_41.

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Actas de conferencias sobre el tema "Concrete admixture"

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"Performance on Used Iron Sand as Concrete Admixture". En 3rd International Conference on Civil, Biological and Environmental Engineering. International Institute of Chemical, Biological & Environmental Engineering, 2016. http://dx.doi.org/10.15242/iicbe.c0216009.

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Pokorný, Jaroslav, Martina Záleská, Milena Pavlíková y Zbyšek Pavlík. "Properties of foamed fine-grained composites containing active mineral admixture". En SPECIAL CONCRETE AND COMPOSITES 2019: 16th International Conference. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0002926.

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Jiang, Meiling, Xianyu Jin y Nanguo Jin. "Influence of Mineral Admixture on Early-Age Concrete Cracking". En 12th Biennial International Conference on Engineering, Construction, and Operations in Challenging Environments; and Fourth NASA/ARO/ASCE Workshop on Granular Materials in Lunar and Martian Exploration. Reston, VA: American Society of Civil Engineers, 2010. http://dx.doi.org/10.1061/41096(366)341.

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Fořt, Jan, Jiří Madĕra, Petr Hotĕk, Martin Mildner y Robert Černý. "Optimization of concrete mixture composition with superabsorbent polymer admixture". En INTERNATIONAL CONFERENCE OF NUMERICAL ANALYSIS AND APPLIED MATHEMATICS ICNAAM 2019. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0026593.

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Guerrero, Hector N., Christine A. Langton y Michael L. Restivo. "Testing and Analysis of Early Age Stress-Strain Development of Concrete Overlay for Reactor In-Situ Decommissioning". En ASME 2011 Pressure Vessels and Piping Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/pvp2011-57902.

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Non-uniform moisture distribution during early age drying and curing of protective concrete overlays for Savannah River Site reactors decommissioned in-situ were expected to result in differential shrinkage that lead to tensile stresses and possible cracking. The goal was to not exceed the concrete tensile strength of 2.8 MPa or compressive strength of 23.8 MPa. An experimental study was performed on the development of shrinkage and creep strains in concrete slab specimens embedded with strain gages and relative humidity sensors at controlled ambient temperature and relative humidity conditions. The experimental data was used to verify the validity of available physics-based methods and code calculations to predict early age shrinkage and creep strains, respectively. Data on the expansive effect of a shrinkage compensating admixture based on CaO was also obtained. Prediction of the surface stress in the test specimen suggests that without the shrinkage compensating admixture, the tensile strength would be slightly exceeded. However with the admixture, the combined effects of shrinkage, creep and expansion due to the admixture is predicted to result in all compressive stresses within the full scale slab, eliminating the possibility of cracking.
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Marušiak, Šimon, Milena Pavlíková y Zbyšek Pavlík. "Diatomite powder as pozzolana active mineral admixture in mortar mix composition". En SPECIAL CONCRETE AND COMPOSITES 2019: 16th International Conference. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0002563.

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Monkman, Sean, Mark MacDonald y Doug Hooton. "The Durability of Concrete Produced Using CO2 as an Admixture". En Fourth International Conference on Sustainable Construction Materials and Technologies. Coventry University, 2016. http://dx.doi.org/10.18552/2016/scmt4s165.

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XU, Peng, Zheng-Jun WANG y Ying GONG. "Progress of straw ash high performance concrete admixture Application Research". En 2018 International Conference on Energy Development and Environmental Protection (EDEP 2018). Paris, France: Atlantis Press, 2018. http://dx.doi.org/10.2991/edep-18.2018.4.

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Yu, Zhao, Wang Yong y Zhang Jianwei. "Application of Fuzzy Comprehensive Evaluation on Choosing Concrete Water Reducing Admixture". En 2010 International Conference on Computing, Control and Industrial Engineering. IEEE, 2010. http://dx.doi.org/10.1109/ccie.2010.129.

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Dobias, Daniel. "RESISTANCE OF CONCRETE MODIFIED WITH STYRENE-ACRYLATE BASED ADMIXTURE TO AGGRESSIVE ENVIRONMENT". En 19th SGEM International Multidisciplinary Scientific GeoConference EXPO Proceedings. STEF92 Technology, 2019. http://dx.doi.org/10.5593/sgem2019/6.2/s26.032.

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Informes sobre el tema "Concrete admixture"

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Watts, Benjamin E., Danielle E. Kennedy, Ethan W. Thomas, Andrew P. Bernier y Jared I. Oren. Long-Term Durability of Cold Weather Concrete : Phase II. Engineer Research and Development Center (U.S.), enero de 2021. http://dx.doi.org/10.21079/11681/39579.

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Recent laboratory results confirm that it is possible to protect concrete from freezing solely using chemical admixtures and indicate that the amount of admixture required may be significantly less than previously recommended. Researchers have also verified that admixture-based freeze protection can produce concrete that is durable to winter exposure for a minimum of 20 years, through petrographic examination of core specimens obtained from past field demonstrations. Freeze protection for concrete using chemical admixtures alone has been an area of active research for 3 decades; however, the most recent methodology recommends very high addition rates of accelerating and corrosion inhibiting admixtures, which result in significant challenges, including slump loss, rapid setting, and potentially excessive temperature rise. As part of a laboratory study, researchers systematically varied the dosage of freeze protection admixtures used in concrete cured in a 23 °F environment. Preliminary findings indicate that a 50% reduction in admixture dose maintained adequate freeze protection and resulted in compressive strengths exceeding those of room-temperature controls at 7 and 28 days. The combination of improved handling, reduced cost, and verified durability associated with the use of admixtures for freeze protection makes a compelling case for broader adoption of this technique in winter operations
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Korhonen, Charles J. y Sherri A. Orchino. Off-the-Shelf Antifreeze Admixture for Concrete Initial Laboratory Investigation. Fort Belvoir, VA: Defense Technical Information Center, enero de 2001. http://dx.doi.org/10.21236/ada392642.

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Wachowski, Lawrence, Paul Tourney, Matthew Miltenberger y Neal Berke. Hydrophobic concrete admixture product testing and validation : contractor's supplemental report for CPC Project F09-AR05A. Construction Engineering Research Laboratory (U.S.), enero de 2018. http://dx.doi.org/10.21079/11681/26076.

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Deb, Robin, Paramita Mondal y Ardavan Ardeshirilajimi. Bridge Decks: Mitigation of Cracking and Increased Durability—Materials Solution (Phase III). Illinois Center for Transportation, diciembre de 2020. http://dx.doi.org/10.36501/0197-9191/20-023.

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Type K cement offers a lower slump than conventional concrete, even at a higher water-to-cement ratio. Therefore, a suitable chemical admixture should be added to the Type K concrete mix design at a feasible dosage to achieve and retain target slump. In this project, a compatibility study was performed for Type K concrete with commercially available water-reducing and air-entraining admixtures. Slump and air content losses were measured over a period of 60 minutes after mixing and a particular mid-range water-reducing admixture was found to retain slump effectively. Furthermore, no significant difference in admixture interaction between conventional and Type K concrete was observed. Another concern regarding the use of Type K concrete is that its higher water-to-cement ratio can potentially lead to higher permeability and durability issues. This study also explored the effectiveness of presoaked lightweight aggregates in providing extra water for Type K hydration without increasing the water-to-cement ratio. Permeability of concrete was measured to validate that the use of presoaked lightweight aggregates can lower water adsorption in Type K concrete, enhancing its durability. Extensive data analysis was performed to link the small-scale material test results with a structural test performed at Saint Louis University. A consistent relation was established in most cases, validating the effectiveness of both testing methods in understanding the performance of proposed shrinkage-mitigation strategies. Stress analysis was performed to rank the mitigation strategies. Type K incorporation is reported to be the most effective method for shrinkage-related crack mitigation among the mixes tested in this study. The second-best choice is the use of Type K in combination with either presoaked lightweight aggregates or shrinkage-reducing admixtures. All mitigation strategies tested in this work were proved to be significantly better than using no mitigation strategy.
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Samson, Eric y Tiewei Zhang. Modeling the effect of a hydrophobic concrete admixture on chloride ingress : contractor's supplemental report for CPC Project F09-AR05A. Construction Engineering Research Laboratory (U.S.), enero de 2018. http://dx.doi.org/10.21079/11681/26087.

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Baral, Aniruddha, Jeffery Roesler y Junryu Fu. Early-age Properties of High-volume Fly Ash Concrete Mixes for Pavement: Volume 2. Illinois Center for Transportation, septiembre de 2021. http://dx.doi.org/10.36501/0197-9191/21-031.

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High-volume fly ash concrete (HVFAC) is more cost-efficient, sustainable, and durable than conventional concrete. This report presents a state-of-the-art review of HVFAC properties and different fly ash characterization methods. The main challenges identified for HVFAC for pavements are its early-age properties such as air entrainment, setting time, and strength gain, which are the focus of this research. Five fly ash sources in Illinois have been repeatedly characterized through x-ray diffraction, x-ray fluorescence, and laser diffraction over time. The fly ash oxide compositions from the same source but different quarterly samples were overall consistent with most variations observed in SO3 and MgO content. The minerals present in various fly ash sources were similar over multiple quarters, with the mineral content varying. The types of carbon present in the fly ash were also characterized through x-ray photoelectron spectroscopy, loss on ignition, and foam index tests. A new computer vision–based digital foam index test was developed to automatically capture and quantify a video of the foam layer for better operator and laboratory reliability. The heat of hydration and setting times of HVFAC mixes for different cement and fly ash sources as well as chemical admixtures were investigated using an isothermal calorimeter. Class C HVFAC mixes had a higher sulfate imbalance than Class F mixes. The addition of chemical admixtures (both PCE- and lignosulfonate-based) delayed the hydration, with the delay higher for the PCE-based admixture. Both micro- and nano-limestone replacement were successful in accelerating the setting times, with nano-limestone being more effective than micro-limestone. A field test section constructed of HVFAC showed the feasibility and importance of using the noncontact ultrasound device to measure the final setting time as well as determine the saw-cutting time. Moreover, field implementation of the maturity method based on wireless thermal sensors demonstrated its viability for early opening strength, and only a few sensors with pavement depth are needed to estimate the field maturity.
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Robert F. Rathbone y Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), octubre de 2002. http://dx.doi.org/10.2172/834172.

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Robert F. Rathbone y Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), abril de 2002. http://dx.doi.org/10.2172/833650.

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Robert F. Rathbone y Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), abril de 2001. http://dx.doi.org/10.2172/833653.

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Robert F. Rathbone y Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), octubre de 2001. http://dx.doi.org/10.2172/833656.

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