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Calculation of Alkali Silica Reaction (ASR) Induced Expansion before Cracking of Concrete 被引量:1
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作者 庄园 钱春香 XU Wen 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2013年第1期110-116,共7页
A calculation method for predicting the formation of alkali-silica gel and analyzing the relationship of ASR induced expansion and aggregate size was proposed. The complicated chemistry of alkali silica reaction was s... A calculation method for predicting the formation of alkali-silica gel and analyzing the relationship of ASR induced expansion and aggregate size was proposed. The complicated chemistry of alkali silica reaction was simplified to be controlled by the diffusion process of chemical ions into reactive aggregates. The transport of chemical ions was described by the Fick's law. The ASR induced expansion was assumed to be directly related to the volume of produced alkali-silica gel. The finally expansion of a representative volume element (RVE) of concrete was then calculated according to the ratio of volume of alkali-silica gel and RVE. The input parameters of the model contains radius of reactive aggregate, volume fraction of reactive aggregate, initial concentration of chemical ions and porosity of cement paste. The applicability of the model was validated by an experiment of ASR-affected concrete specimens containing glass aggregate. It is shown that the amount of alkali-silica gel and ASR induced expansion can be well predicted. The expansion increasing with the decreasing aggregate size can be reproduced by the proposed model. 展开更多
关键词 alkali silica reaction EXPANSION calculation model aggregate size
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Multiscale Homogenization Analysis of Alkali–Silica Reaction (ASR) Effect in Concrete 被引量:2
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作者 Roozbeh Rezakhani Mohammed Alnaggar Gianluca Cusatis 《Engineering》 SCIE EI 2019年第6期1139-1154,共16页
The alkali silica reaction (ASR) is one of the major long-term deterioration mechanisms occurring in con- crete structures subjected to high humidity levels, such as bridges and dams. ASR is a chemical reaction betwee... The alkali silica reaction (ASR) is one of the major long-term deterioration mechanisms occurring in con- crete structures subjected to high humidity levels, such as bridges and dams. ASR is a chemical reaction between the silica existing inside the aggregate pieces and the alkali ions from the cement paste. This chemical reaction produces ASR gel, which imbibes additional water, leading to gel swelling. Damage and cracking are subsequently generated in concrete, resulting in degradation of its mechanical proper- ties. In this study, ASR damage in concrete is considered within the lattice discrete particle model (LDPM), a mesoscale mechanical model that simulates concrete at the scale of the coarse aggregate pieces. The authors have already modeled successfully ASR within the LDPM framework and they have calibrated and validated the resulting model, entitled ASR-LDPM, against several experimental data sets. In the pre- sent work, a recently developed multiscale homogenization framework is employed to simulate the macroscale effects of ASR, while ASR-LDPM is utilized as the mesoscale model. First, the homogenized behavior of the representative volume element (RVE) of concrete simulated by ASR-LDPM is studied under both tension and compression, and the degradation of effective mechanical properties due to ASR over time is investigated. Next, the developed homogenization framework is utilized to reproduce experimental data reported on the free volumetric expansion of concrete prisms. Finally, the strength degradation of prisms in compression and four-point bending beams is evaluated by both the mesoscale model and the proposed multiscale approach in order to analyze the accuracy and computational ef - ciency of the latter. In all the numerical analyses, different RVE sizes with different inner particle realiza- tions are considered in order to explore their effects on the homogenized response. 展开更多
关键词 Multiscale homogenization Representative volume element alkalisilica reaction Lattice discrete particle model
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Alkali-Silica Reaction Inhibited by LiOH and Its Mechanism 被引量:2
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作者 莫祥银 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2003年第1期13-16,共4页
A high alkali reactive aggregate zeolitization perlite was used to test the long term effectiveness of LiOH in inhibiting alkali silica reaction.In this paper,the rigorous conditions were designed that the mortar b... A high alkali reactive aggregate zeolitization perlite was used to test the long term effectiveness of LiOH in inhibiting alkali silica reaction.In this paper,the rigorous conditions were designed that the mortar bars had been cured at 80℃ for 3 years after autoclaved 24 hours at 150℃.Under this condition,LiOH was able to inhibit the alkali silica reaction long term effectiveness.Not only the relationship between the molar ratio of n(Li)/(Na) and the alkali contents in systems was established, but also the governing mechanism of such effects was also studied by SEM. 展开更多
关键词 lithium compounds alkali silica reaction long term performance MECHANISM
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Effect of Anti-freezing Admixtures on Alkali-silica Reaction in Mortars 被引量:5
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作者 柳俊哲 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2005年第2期80-82,共3页
The influence of anti-freezing admixture on the alkali aggregate reaction in mortar was analyzed with accelerated methods. It is confirmed that the addition of sodium salt ingredients of anti-freezing admixture accele... The influence of anti-freezing admixture on the alkali aggregate reaction in mortar was analyzed with accelerated methods. It is confirmed that the addition of sodium salt ingredients of anti-freezing admixture accelerates the alkali silica reaction to some extent, whereas calcium salt ingredient of anti-freezing admixture reduces the expansion of alkali silica reaction caused by high alkali cement. It is found that the addition of the fly ash considerably suppresses the expansion of alkali silica reaction induced by the anti-freezing admixtures. 展开更多
关键词 anti-freezing admixture alkali-silica reaction reactive aggregates fly ash
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Efficacy of Aluminum Hydroxides as Inhibitors of Alkali-Silica Reactions 被引量:2
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作者 Alexey Brykov Anna Anisimova 《Materials Sciences and Applications》 2013年第12期1-6,共6页
A comparative study of amorphous and crystalline forms of commercial aluminum hydroxides as inhibitors of alkalisilica reactions in Portland cement mortars has been performed. It was found that at dosages of 1% to 3%,... A comparative study of amorphous and crystalline forms of commercial aluminum hydroxides as inhibitors of alkalisilica reactions in Portland cement mortars has been performed. It was found that at dosages of 1% to 3%, amorphous aluminum hydroxide can efficiently inhibit alkali-silica expansion of Portland cement compositions. High inhibiting activity of amorphous Al(OH)3 additives may be explained by their ability to actively bind Ca(OH)2 formed by the hydration of silicate phases of cement, to form ettringite (with participation of gypsum). Crystalline Al(OH)3 additives that do not possess the ability to interact with Ca(OH)2 even after additional grinding, however, demonstrate week properties to inhibit alkali-silica expansion. This may indicate that the inhibitory effect of Al(OH)3 at least—partly, may be given by its influence on the concentration of Al3+ ions in the pore solution. Some expansion of the samples with admixtures of Al(OH)3 observed during the alkaline expansion accelerated test procedure is not associated with the formation of ettringite and is only due to alkali-silicate reactions. 展开更多
关键词 Aluminum HYDROXIDE alkali-silica reaction INHIBITION Portland CEMENT Concrete
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Effect of the Composite of Natural Zeolite and Fly Ash on Alkali-Silica Reaction
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作者 封孝信 FENGNai-qian HANDong 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2003年第4期93-96,共4页
The effect of the composite of natural zeolite and fly ash on alkali-silica reaction (ASR) was studied with natural alkali-reactive aggregate and quartz glass aggregate respectively.The expansive experiment of mortar ... The effect of the composite of natural zeolite and fly ash on alkali-silica reaction (ASR) was studied with natural alkali-reactive aggregate and quartz glass aggregate respectively.The expansive experiment of mortar bar and concrete prism was completed.The results show that ASR can be suppressed effectively by the composite of natural zeolite and fly ash. 展开更多
关键词 natural zeolite fly ash alkali-silica reaction (asr)
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The Impact of Aluminum- and Iron-Bearing Admixtures on the Resistance of Portland Cement Mortars to Alkali-Silica Reaction and Sulfate Attack 被引量:1
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作者 Alexey Brykov Anna Anisimova +2 位作者 Natalya Rozenkova Mohammed Hadi Maxim Mokeev 《Materials Sciences and Applications》 2015年第6期539-548,共10页
Study of sulfate resistance of mortars with aluminum- and iron-bearing admixtures (Al(OH)3, Al2(SO4)3, FeSO4, Fe2(SO4)3) in conditions close to those established in ASTM C 1012, and the study of the mitigation effect ... Study of sulfate resistance of mortars with aluminum- and iron-bearing admixtures (Al(OH)3, Al2(SO4)3, FeSO4, Fe2(SO4)3) in conditions close to those established in ASTM C 1012, and the study of the mitigation effect of these admixtures on alkali-silica reaction in accordance with accelerated “mortar bar” test ( GOST 8269.0, ASTM C 1260) were performed. Iron (II) and (III) sulfates show ability for mitigation alkali-silica reaction, while also, in contrast with Al-bearing substances, do not induce the drastic reducing of the initial setting time and do not promote the progress of sulfate corrosion. Compared with FeSO4, iron (III) sulfate has moderate deleterious impact on the early strength of cement paste and can be of interest alone as an inhibitor of ASR. Iron (II) sulfate may be used together with aluminum sulfate to offset the accelerating effect of the latter on the setting of cement paste and to reduce a risk of sulfate corrosion. During prolonged water storage, the mortar elongation and secondary ettringite formation do not occur, even when Al2(SO4)3 is available. Therefore, the investigated admixtures cannot act as agents of internal sulfate attack, however, Al2(SO4)3 can enhance the outer sulfate attack. 展开更多
关键词 alkali-silica reaction SULFATE Attack Mitigation ALUMINUM SULFATE IRON SULFATE Portland Cement
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Effect of Mineral Admixtures on Alkali-Silica Reaction
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作者 张承志 WANG Aiqin 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2008年第1期16-19,共4页
The influence of silica fume, slag and fly ash on alkali-silica reaction under the condition of 70 ℃ is studied. The results show that silica, slag and fly ash may inhibit alkali-silica reaction only under suitable c... The influence of silica fume, slag and fly ash on alkali-silica reaction under the condition of 70 ℃ is studied. The results show that silica, slag and fly ash may inhibit alkali-silica reaction only under suitable content. When the content is less than 10%, silica fume does not markedly influence the expansion of alkali- silica reaction. When the content is 15%-20%, silica fume only may delay the expansion of alkali-silica reaction. When the content is 30%-70%, slag may only delay the expansion of alkali-silica reaction, but cannot inhibit the expansion of alkali-silica reaction. When the content is 10%, fly ash does not markedly influence the expansion of alkali-silica reaction. When the content is 20%-30%, fly ash may only delay the expansion of alkali-silica reaction, but cannot inhibit the expansion of alkali-silica reaction. When the content is over 50%, it is possible that fly ash can inhibit effectively alkali-silica reaction. 展开更多
关键词 mineral admixture alkali-silica reaction EFFECTIVENESS
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Effect of Pozzolanic Reaction Products on Alkali-silica Reaction
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作者 魏风艳 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2006年第3期168-171,共4页
The effect of fly ash on controlling alkail-silica rection (ASR) in simudated alkali solution was studied. The expausion of mortar bars and the content of Ca( OH)2 in cement paste cured at 80 °G for 91 d were... The effect of fly ash on controlling alkail-silica rection (ASR) in simudated alkali solution was studied. The expausion of mortar bars and the content of Ca( OH)2 in cement paste cured at 80 °G for 91 d were measured. Traasmission electron microscopy (TEM) and high-resolution transmission electron microscot9 (HRTEM) were employed to study the microstructure of C-S-H. TEM/ energy dispersive spectroscopy (EDS) leas then used to determine the composition of C-S-H. The pore structure of the paste was analyzed by mercury intntsion porosimetry (MIP). The results show that the contents of fly ash of 30% and 45% can well inhibit ASR. And the content of Ca(OH) 2 decreases with the increase of fly ash. That fly ash reacted with Ca(OH)2 to produce C-S-H with a low Ca/Si molar ratio could bind more Na^+ and K^+ ious, and produce a reduction in the amount of soluble alkali available for ASR. At the same time, the C- S- H produced by pozzolanic reaction converted large pores to snudler ones ( gel pores smaller than 10 nm ) to deusify the pore structure. Perhaps that could inhibit alkali trausport to aggregate for ASR. 展开更多
关键词 alkali Ca/ Si molar ratio C-S-H alkali-silica reaction
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The Mechanism of the Eeffect of Mineral Admixtures on the Expansion of Aalkali-silica Reaction
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作者 王爱勤 张承志 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2008年第3期376-380,共5页
On the base of the influence rule of silica fume, slag and fly ash on alkali-silica reaction under the condition of 70 ℃, the mechanism of the effect of mineral admixtures on alkali-silica reaction is studied further... On the base of the influence rule of silica fume, slag and fly ash on alkali-silica reaction under the condition of 70 ℃, the mechanism of the effect of mineral admixtures on alkali-silica reaction is studied further in the paper. The results show that the effects of mineral admixtures on alkali-silica reaction are mainly chemistry effect and surface physichemistry effect. Under suitable condition, the chemistry effect may make alkali-silica reaction to be inhibited effectively, but the physichemistry effect only make alkali-silica reaction to be delayed. The chemistry effect and the physichemistry effect of minerals admixture are relative to the content of Ca(OH)2 in system. Under the condition that there is a large quantity of Ca(OH)2, mineral admixture cannot inhibit alkali-silica reaction effectively. Only when Ca(OH)2 in the system is very less, it is possible that mineral admixture inhibits alkali-silica reaction effectively. 展开更多
关键词 mineral admixture alkali-silica reaction MECHANISM
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Calcined Clay Pozzolan as an Admixture to Mitigate the Alkali-Silica Reaction in Concrete
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作者 James Sarfo-Ansah Eugene Atiemo +2 位作者 Kwabena Appiah Boakye Delali Adjei Albert A. Adjaottor 《Journal of Materials Science and Chemical Engineering》 2014年第5期20-26,共7页
Calcined clay pozzolan has been used to replace varying portions of high alkali Portland limestone cement in order to study its effect on the alkali-silica reaction (ASR). Portland limestone cement used for the study ... Calcined clay pozzolan has been used to replace varying portions of high alkali Portland limestone cement in order to study its effect on the alkali-silica reaction (ASR). Portland limestone cement used for the study had a total Na2Oeq of 4.32. Mortar-bar expansion decreased as pozzolan content in the cement increased. The highest expansion was recorded for reference bars with no pozzolan, reaching a maximum of 0.35% at 42 days whilst the expansion was reduced by between 42.5% and 107.8% at 14 days and between 9.4% and 16.4% at 84 days with increasing calcined clay pozzolan content. Mortar bars with 25% pozzolan were the least expansive recording expansion less than 0.1% at all test ages. X-ray diffractometry of the hydrated blended cement paste powders showed the formation of stable calcium silicates in increasing quantities whilst the presence of expansive alkali-silica gel, responsible for ASR expansion, decreased as pozzolan content increased. The study confirms that calcined clay pozzolan has an influence on ASR in mortar bars and causes a significant reduction in expansion at a replacement level of 25%. 展开更多
关键词 CALCINED CLAY POZZOLAN alkali-silica reaction Expansion Sodium silicaTE gel Calcium silicaTES
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Ultrafine Silica Additives Behavior during Alkali-Silica Reaction Long-Term Expansion Test
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作者 Alexey Brykov Mikhail Voronkov Maxim Mokeev 《Materials Sciences and Applications》 2014年第2期66-72,共7页
A silica fume, precipitated silica, metakaolin and siliceous fly ash behavior as constituents of mortars was studied, while mortar samples have been tested for long-term alkali-silica reaction expansion in accordance ... A silica fume, precipitated silica, metakaolin and siliceous fly ash behavior as constituents of mortars was studied, while mortar samples have been tested for long-term alkali-silica reaction expansion in accordance to the GOST 8269.0 specification. Solid-state 29Si-MAS NMR spectroscopy and thermogravimetric analysis were used to describe Portland cement hydration, supplementary cementitious material pozzolanic reaction and to establish a structure of products of those processes. It was found that long-term test conditions, in contrast to the accelerated test, do not affect the composition of products formed too much, compared to normal conditions. This allows results obtained with long-term test to be expected as more relevant in terms of predicting of supplementary cementitious materials inhibiting properties. 展开更多
关键词 alkali-silica reaction SUPPLEMENTARY Cementitious Materials MAS NMR THERMOGRAVIMETRIC Analysis Pozzolanic reaction
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The Mitigation of Alkali-Silica Reactions by Aluminum-Bearing Substances
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作者 Alexey Brykov Anna Anisimova Natalia Rozenkova 《Materials Sciences and Applications》 2014年第6期363-367,共5页
An ability of aluminum-bearing substances-amorphous aluminum hydroxide, aluminum sulphate and basic aluminum sulphate to mitigate alkali-silica reactions in Portland cement mortars has been studied. At equivalent dosa... An ability of aluminum-bearing substances-amorphous aluminum hydroxide, aluminum sulphate and basic aluminum sulphate to mitigate alkali-silica reactions in Portland cement mortars has been studied. At equivalent dosages in terms of Al2O3, these substances are ranged in the following order in respect of inhibiting effect: Al(OH)1.78(SO4)0.61 ≥ Al2(SO4)3 > Al(OH)3. It is found that the plasticizing agents of the main types used in cement compositions have no influence on the inhibiting effect of aluminum-bearing admixtures. To control the setting time of cement paste, iron(II) sulphate may be used for partial substitution of Al2SO4·18H2O, and this operation is not influence on the results of ASR expansion test. 展开更多
关键词 alkali-silica reaction MITIGATION ALUMINUM HYDROXIDE ALUMINUM Sulphate Basic ALUMINUM Sulphate Concrete Iron(II) Sulphate Portland Cement SUPERPLASTICIZERS Water-Reducing ADMIXTURES
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ASR抑制下高性能混凝土的长期抗卤水腐蚀性
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作者 程明 余红发 +2 位作者 张丽芳 刘连新 刘成奎 《建筑材料学报》 EI CAS CSCD 北大核心 2023年第3期310-316,共7页
以中国西北地区高浓度盐碱环境为背景,研究了含潜在碱活性细骨料的大掺量矿物掺合料高性能混凝土(HPC)在Na^(+)-Cl^(-)-SO_(4)^(2-)型卤水中的力学性能和损伤演变.结果表明:在卤水浸泡3650 d时,HPC的相对动弹性模量大于90%,抗腐蚀系数大... 以中国西北地区高浓度盐碱环境为背景,研究了含潜在碱活性细骨料的大掺量矿物掺合料高性能混凝土(HPC)在Na^(+)-Cl^(-)-SO_(4)^(2-)型卤水中的力学性能和损伤演变.结果表明:在卤水浸泡3650 d时,HPC的相对动弹性模量大于90%,抗腐蚀系数大于1,线性膨胀率小于0.12%;较高的当量碱含量在一定程度上加剧HPC的碱硅酸反应(ASR);引气能够提高HPC的抗卤水腐蚀能力,降低ASR引起的膨胀;采用大掺量矿物掺合料和潜在碱活性细骨料制备的强度等级为C50的HPC,在Na^(+)-Cl^(-)-SO_(4)^(2-)型卤水中具有优良的长期耐久性. 展开更多
关键词 高性能混凝土 卤水腐蚀 碱-硅酸反应 相对动弹性模量 强度 膨胀率
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Effect of Glass Powder on Chloride Ion Transport and Alkali-aggregate Reaction Expansion of Lightweight Aggregate Concrete 被引量:3
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作者 王智 史才军 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS 2009年第2期312-317,共6页
The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated. Ground blast furnace slag, coal fly... The effects of glass powder on the strength development, chloride permeability and potential alkali-aggregate reaction expansion of lightweight aggregate concrete were investigated. Ground blast furnace slag, coal fly ash and silica fume were used as reference materials. The re- placement of cement with 25% glass powder slightly decreases the strengthes at ? and 28 d, but shows no effect on 90 d's. Silica fume is very effective in improving both the strength and chloride penetration resistance, while ground glass powder is much more effective than blast furnace slag and fly ash in improving chloride penetration resistance of the concrete. When expanded shale or clay is used as coarse aggregate, the concrete containing glass powder does not exhibit deleterious expansion even if alkali-reactive sand is used as fine aggregate of the concrete. 展开更多
关键词 waste glass powder fly ash blast furnace slag silica fume lightweight aggregate chloride permeability alkali-aggregate reaction
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Alkali-Silica Reactivity and Strength of Mortars with Expanded Slate, Expanded Glass or Perlite
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作者 Mehrzad Zahabi Aly Said 《Open Journal of Civil Engineering》 2021年第1期119-133,共15页
Lightweight aggregates are increasingly used in concrete construction. They reduce concrete selfweight furnishing a structural advantage. In contrast, the mechanical properties and durability of lightweight concrete c... Lightweight aggregates are increasingly used in concrete construction. They reduce concrete selfweight furnishing a structural advantage. In contrast, the mechanical properties and durability of lightweight concrete can become the governing factor on lightweight aggregate replacement ratios. Alkali-Silica Reactison (ASR) and compressive strength of mortar samples with expanded slate, expanded glass or perlite, covering the spectrum of internal porosity and weight of lightweight aggregates, were evaluated. Scanning electron microscopy was utilized to evaluate the contribution of the aggregates’ porosity and chemical composition in inhibiting ASR. Perlite, owing to its highly porous microstructure and lower matter excelled in ASR expansion while chemical composition and denser microstructure of the heavier expanded slate resulted in more signified late ASR expansion and higher compressive strength. An attempt in visual inspection of ASR attack of alkali metal ions on silica-rich expanded glass using an ultra-accelerated exposure to sodium hydroxide solution was made</span></span><span style="font-family:Verdana;">. 展开更多
关键词 Lightweight Concrete alkali-silica reaction Expanded Glass Aggregate Expanded Slate Aggregate Perlite Aggregate
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冻融循环-碱硅酸反应对再生混凝土损伤的影响
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作者 秦拥军 呙哲懿 +1 位作者 张驰 张亚斌 《混凝土》 CAS 北大核心 2024年第10期10-15,31,共7页
我国西北地区长期处于严寒以及盐渍土环境会导致混凝土耐久性的下降。为了研究再生混凝土在冻融循环(FTC)后,受碱硅酸反应(ASR)而发生二次损伤的规律,以再生粗骨料为变量,将再生混凝土分别进行20次、40次冻融循环后浸泡在80℃的1 mol/L ... 我国西北地区长期处于严寒以及盐渍土环境会导致混凝土耐久性的下降。为了研究再生混凝土在冻融循环(FTC)后,受碱硅酸反应(ASR)而发生二次损伤的规律,以再生粗骨料为变量,将再生混凝土分别进行20次、40次冻融循环后浸泡在80℃的1 mol/L NaOH溶液中进行ASR 28 d,研究再生混凝土表面形貌、膨胀率、质量损失率、相对动弹性模量等损伤指标,分析FTC作用下ASR对再生混凝土二次损伤的机理。试验结果表明:前期冻融次数的增加使得内部裂缝增多导致后期ASR反应速率提升,随着FTC次数越多,再生粗骨料取代率越高,再生混凝土受ASR作用下膨胀率越大,在再生粗骨料取代率为70%时混凝土膨胀率达到最大值;当再生粗骨料取代率小于50%时,由于试件骨料初始损伤相对较小以及碱活性较弱,呈现超叠加损伤效应,当再生粗骨料取代率为50%以上时,ASR对混凝土的二次损伤变大,产生的硅酸盐凝胶总量增多,质量损失率也随之增大;随着冻融循环次数以及再生粗骨料取代率的增加,使得试件受到更多的基体损伤,且远大于附着砂浆二次水化过程中的结构密实作用导致混凝土的相对动弹性模量的下降并且随着再生粗骨料取代率的增大,骨料中更多碱活性物质被暴露在碱溶液下,给后期ASR提供了良好的反应环境,相对动弹性模量的下降程度越大,但前期的FTC并没有影响ASR反应二次损伤相对弹性模量规律。 展开更多
关键词 再生混凝土 碱-硅酸反应 冻融循环 二次损伤 耐久性
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粉煤灰对ASR的抑制及有效性评估 被引量:8
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作者 卢都友 吕忆农 +1 位作者 许仲梓 唐明述 《硅酸盐学报》 EI CAS CSCD 北大核心 2003年第5期498-503,共6页
以中国快速砂浆棒法为基础 ,分别研究了在 40 ,60 ,80℃养护条件下低钙粉煤灰对硅质砾石、沸石化珍珠岩和石英玻璃碱硅酸反应 (alkalisilicareaction ,ASR)膨胀的抑制作用。讨论了集料碱活性、养护温度对粉煤灰抑制ASR效果的影响和建立... 以中国快速砂浆棒法为基础 ,分别研究了在 40 ,60 ,80℃养护条件下低钙粉煤灰对硅质砾石、沸石化珍珠岩和石英玻璃碱硅酸反应 (alkalisilicareaction ,ASR)膨胀的抑制作用。讨论了集料碱活性、养护温度对粉煤灰抑制ASR效果的影响和建立粉煤灰及其它矿物外加剂抑制ASR有效性评估方法的技术路线和问题。结果表明 :粉煤灰抑制ASR的效果与集料碱活性和养护温度密切相关。一定养护温度下 ,集料活性越大 ,抑制效果越差 ;对特定活性集料 ,养护温度越高 ,抑制效果越差。粉煤灰对不同集料和同种集料不同养护温度下ASR膨胀抑制效果差异 ,主要与ASR历程有关 ,即与集料ASR本身特性有关。特定集料和养护条件下粉煤灰对ASR膨胀的抑制效果不能简单推广至其它种类不同的集料和养护条件。粉煤灰抑制ASR有效性应根据工程评价目的和要求分别确定。 展开更多
关键词 碱硅酸反应 粉煤灰 矿物外加剂 活性集料 养护温度 有效性
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温度和集料对混凝土ASR有效碱的影响规律 被引量:5
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作者 庄园 钱春香 徐文 《建筑材料学报》 EI CAS CSCD 北大核心 2012年第2期184-189,共6页
从碱硅酸反应(ASR)的化学本质出发,将有效碱进一步定义为扩散进入活性集料内并与活性SiO2发生化学反应的液相碱.在此基础上,以熔融石英玻璃为活性集料,研究养护温度、活性集料粒径和活性集料掺量(质量分数)对单颗活性集料内有效碱含量(... 从碱硅酸反应(ASR)的化学本质出发,将有效碱进一步定义为扩散进入活性集料内并与活性SiO2发生化学反应的液相碱.在此基础上,以熔融石英玻璃为活性集料,研究养护温度、活性集料粒径和活性集料掺量(质量分数)对单颗活性集料内有效碱含量(质量分数)的影响;结合Fick第一定律和第二定律,建立了有效碱浓度的计算模型.结果表明:养护温度对单颗活性集料内有效碱含量影响显著;活性集料粒径对单颗活性集料内有效碱含量无显著影响;随着活性集料掺量的增加,单颗活性集料内有效碱含量呈现出一定的下降趋势;所建立的有效碱浓度计算模型可以有效反映养护温度、活性集料粒径和活性集料掺量对其的影响,对后续建模工作有一定的参考价值. 展开更多
关键词 碱硅酸反应 养护温度 活性集料 集料粒径 集料掺量 计算方法
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粉煤灰抑制ASR的机制 被引量:17
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作者 魏风艳 许仲梓 《材料科学与工程学报》 CAS CSCD 北大核心 2005年第5期537-541,共5页
本文研究粉煤灰对ASR的抑制作用。测定了不同粉煤灰掺量砂浆棒膨胀率、水泥石中Ca(OH)2含量以及主要水化产物C-S-H凝胶的微观结构和化学组成,并对粉煤灰抑制ASR的机制进行探讨。结果表明:随粉煤灰掺量增加,其对ASR具有显著的抑制效果。... 本文研究粉煤灰对ASR的抑制作用。测定了不同粉煤灰掺量砂浆棒膨胀率、水泥石中Ca(OH)2含量以及主要水化产物C-S-H凝胶的微观结构和化学组成,并对粉煤灰抑制ASR的机制进行探讨。结果表明:随粉煤灰掺量增加,其对ASR具有显著的抑制效果。水泥石中Ca(OH)2含量不断减少,二次反应生成大量低n(Ca)/n(Si)的C-S-H凝胶。随n(Ca)/n(Si)降低,C-S-H凝胶中固溶了大量的Al,凝胶的固碱能力增强,从而使混凝土孔溶液中的有效碱大大减少,减轻了ASR程度。凝胶的固碱能力增强除了因n(Ca)/n(Si)降低,使C-S-H凝胶的固碱能力增强之外。还可能因为Al3+代替Si4+形成[AlO4]5-四面体,由于Al3+比Si4+少一价,引起电价不平衡,系统带负电,因此碱离子更容易进入C-S-H凝胶中,减少了碱与活性集料反应的机会。 展开更多
关键词 CA/SI比 C-S-H 碱-硅酸反应
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