The alkali–silica reaction (ASR) starts with the dissolution of silica in alkali-reactive aggregates. Besides the thermodynamic basics of silica dissolution, kinetic data are needed to model ASR in order to describe the temporal course of the reaction. Although the dissolution kinetics of silica has been investigated frequently, data for concrete-like environments (pH > 12) and under special influences, such as de-icer impact by sodium chloride (NaCl) or the release of aluminium (Al) from feldspars, are rare or missing. In the present study, long-term (2.5 years) dissolution tests were performed to obtain kinetic data for two types of aggregate (granodiorite, rhyolite) under concrete-like conditions (pH 13.8, with/without calcium hydroxide (Ca(OH)₂) and sodium chloride) at temperatures of 25, 45 and 60°C. The findings show that silica dissolution rates effective for ASR differ up to four orders of magnitude, ranging from (log r₁) −13.13 to −9.96 mol/m²s as a function of aggregate type, temperature, sodium chloride concentration and calcium hydroxide. Besides a predominant influence of temperature and calcium hydroxide, sodium chloride promotes the dissolution of silica and lowers the aluminium concentration, especially at higher temperatures. The activation energy for silica dissolution (84 ± 4 kJ/mol) did not change significantly in the presence of sodium chloride.

中文翻译：

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聚集体溶解动力学

碱-硅反应 (ASR) 始于二氧化硅在碱反应聚集体中的溶解。除了二氧化硅溶解的热力学基础知识外，还需要动力学数据来模拟 ASR，以描述反应的时间过程。尽管经常研究二氧化硅的溶解动力学，但混凝土类环境 (pH > 12) 和特殊影响下的数据，例如氯化钠 (NaCl) 的除冰作用或长石中铝 (Al) 的释放，很少见或缺失。在本研究中，进行了长期（2.5 年）溶解试验，以获得两种类型骨料（花岗闪长岩、流纹岩）在类混凝土条件（pH 13.8，有/无氢氧化钙（Ca(OH) ₂) 和氯化钠) 在 25、45 和 60°C 的温度下。研究结果表明，对 ASR 有效的二氧化硅溶解速率相差多达四个数量级，范围从 (log  r ₁ ) −13.13 到 −9.96 mol/m ² s，作为聚集体类型、温度、氯化钠浓度和氢氧化钙的函数. 除了温度和氢氧化钙的主要影响外，氯化钠还促进二氧化硅的溶解并降低铝的浓度，尤其是在较高温度下。二氧化硅溶解的活化能 (84 ± 4 kJ/mol) 在氯化钠存在下没有显着变化。