Experiments and field observations have shown that supplementary cementitious materials (SCMs) mitigate the risk of alkali-silica reaction (ASR) in Portland cement blends, but this is difficult to describe thermodynamically due to the lack of appropriate thermodynamic database information, and challenges in defining the kinetic factors. This paper examines how four well-known SCMs (namely ground granulated blast furnace slag, silica fume, metakaolin, and fly ash) mitigate ASR, by using a multi-stage simulation and a newly extended thermodynamic database. Calcium hydroxide consumption by SCM hydration, dilution of available alkalis, and alkali binding in calcium-alkali-aluminosilicate hydrate solid solutions, play pivotal roles in understanding the influence of SCMs in ASRs. Blending aluminium-rich SCMs in ASR-prone systems appears to act by preventing the dissolution of reactive silica in aggregates rather than by suppressing the formation of ASR products. This paper provides new thermodynamic insights into the mechanisms by which SCMs enhance concrete durability against ASR.

中文翻译：

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混合水泥中碱-硅反应的热力学模型


实验和现场观察表明，辅助胶凝材料 (SCM) 可以降低波特兰水泥混合物中发生碱硅反应 (ASR) 的风险，但由于缺乏适当的热力学数据库信息以及定义方面的挑战，这很难从热力学角度进行描述。动力学因素。本文通过使用多阶段模拟和新扩展的热力学数据库，研究了四种著名的 SCM（即磨碎的粒状高炉矿渣、硅灰、偏高岭土和粉煤灰）如何减轻 ASR。 SCM 水合消耗的氢氧化钙、可用碱的稀释以及钙-碱-铝硅酸盐水合物固溶体中的碱结合，在理解 SCM 对 ASR 的影响方面发挥着关键作用。在容易发生 ASR 的系统中混合富铝 SCM 似乎是通过防止聚集体中活性二氧化硅的溶解来起作用，而不是通过抑制 ASR 产物的形成来起作用。本文提供了关于 SCM 增强混凝土抗 ASR 耐久性的机制的新热力学见解。