Liu Xiang, Mao Zhongyang, Yi Lei, Fan Zhiyuan, Zhang Tao, Huang Xiaojun, Deng Min, Tang Mingshu
College of Materials Science and Engineering, Nanjing Tech University, Nanjing 211800, China.
State Key Laboratory of Materials-Oriented Chemical Engineering, Nanjing Tech University, Nanjing 211800, China.
Materials (Basel). 2022 Apr 13;15(8):2853. doi: 10.3390/ma15082853.
The main aim of this study was focused on the Method of testing alkali-carbonate reaction activity to avoid alkali-carbonate reaction damage. In this paper, the alkali-carbonate reaction activity and alkali-silica reaction activity of ten kinds of aggregates were determined and analysed by existing standards and methods, by making specimens with aggregates of 2.5-5 mm and 5-10 mm particle size, cured in 1 mol/L tetramethyl ammonium hydroxide solution at 60 °C and 80 °C. Tetramethyl ammonium hydroxide solution was used to exclude the expansion caused by alkali-silica reaction. Effects of aggregate particle size and curing temperature on the expansion of samples were systematically investigated to determine alkali-carbonate reactivity of aggregates. In order to explore the relationship between stress and strain of aggregates, these aggregates were prepared into compacted bodies to test their stress and try to discover the pattern. The results showed that the expansion of the mould specimen prepared by the aggregate of 5-10 mm particle size, cured in 1 mol/L tetramethyl ammonium hydroxide solution at 80 °C was greater than 0.1% after 42 days, which could be used as a reference criterion to determine the alkali-carbonate reaction activity of the aggregate. In addition, the expansion stress test suggest that the alkali-carbonate reaction can generate expansion stress. The expansion stress of aggregates with alkali-carbonate reaction activity were much larger than that of aggregates without alkali-carbonate reaction activity. Through SEM and EDX analysis of the products of the alkali-carbonate reaction, it was shown that the dolomite crystals in the dolomitic aggregates reacted with the TMAH solution and resulted in alkali-carbonate reaction, forming calcite and brucite.
本研究的主要目的集中在测试碱 - 碳酸盐反应活性的方法上，以避免碱 - 碳酸盐反应破坏。本文采用现行标准和方法，通过制作粒径为2.5 - 5mm和5 - 10mm的集料试样，在60℃和80℃的1mol/L四甲基氢氧化铵溶液中养护，测定并分析了十种集料的碱 - 碳酸盐反应活性和碱 - 硅酸反应活性。使用四甲基氢氧化铵溶液排除碱 - 硅酸反应引起的膨胀。系统研究了集料粒径和养护温度对试样膨胀的影响，以确定集料的碱 - 碳酸盐反应性。为了探索集料应力与应变之间的关系，将这些集料制成压实体来测试其应力并试图发现规律。结果表明，粒径为5 - 10mm的集料在80℃的1mol/L四甲基氢氧化铵溶液中养护42天后，模具试样的膨胀率大于0.1%，这可作为确定集料碱 - 碳酸盐反应活性的参考标准。此外，膨胀应力试验表明碱 - 碳酸盐反应会产生膨胀应力。具有碱 - 碳酸盐反应活性的集料的膨胀应力远大于无碱 - 碳酸盐反应活性的集料。通过对碱 - 碳酸盐反应产物的扫描电子显微镜（SEM）和能谱分析（EDX）表明，白云质集料中的白云石晶体与四甲基氢氧化铵溶液反应导致碱 - 碳酸盐反应，形成方解石和水镁石。
