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Abstract：
Despite extensive research, the relationship between the progression of the alkali-silica reaction (ASR) and the expansion of concrete due to ASR, particularly for the heterogeneous aggregate with slow reactivity, is not thoroughly understood. In this paper, the dissolution kinetics of reactive silica present in sandstone when exposed to NaOH solutions, alongside the expansion characteristics of rock prisms under ASR conditions, were studied. The experimental results indicate that ASR behaves as a first-order reaction, accompanied by an exponential decrease in the concentration of OH- over time, and the dissolution rate of silica is predominantly governed by diffusion dynamics. Notably, increasing the temperature accelerates ASR, which augments the expansive pressure in a confined and limited space, leading to more significant aggregate expansion. Conversely, higher temperatures also result in a diminished retention of ASR gels within the aggregate, leading to the mitigation of ASR expansion. Our findings underscore that larger aggregates retain a greater quantity of gels, resulting in more pronounced expansion. To establish an ASR prediction model based on the relationship of the ASR expansion of concrete to high and low temperatures, the parameters such as the range of curing temperatures and the grading size of aggregates should be carefully considered for the experiments.
摘要：
尽管进行了广泛的研究,碱-二氧化硅反应（ASR）的进展与ASR引起的混凝土膨胀之间的关系，特别是对于反应性慢的异质聚集体，没有被彻底理解。在本文中,当暴露于NaOH溶液时，砂岩中存在的反应性二氧化硅的溶解动力学，随着岩石棱柱在ASR条件下的膨胀特性，被研究过。实验结果表明，ASR表现为一级反应，伴随着OH-浓度随时间的指数下降，二氧化硅的溶解速率主要受扩散动力学控制。值得注意的是,升高温度会加速ASR，这增加了有限空间中的膨胀压力，导致更显著的总量扩张。相反，较高的温度也导致ASR凝胶在聚集体中的保留减少，导致ASR扩展的缓解。我们的发现强调，较大的聚集体保留了更大量的凝胶，导致更明显的扩张。基于混凝土ASR膨胀与高低温的关系,建立ASR预测模型,在实验中，应仔细考虑固化温度范围和骨料分级尺寸等参数。
