Abstract Both alkalis and calcium play essential roles in the formation of alkali-silica reaction (ASR) products. Investigation of their combined effect helps to better understand the conditions of ASR. In this study, samples with a constant Ca/Si ratio of 0.3 but different K(or Na)/Si and K/Na ratios have been synthesized at 80 °C. Experimental studies and thermodynamic modelling show that a sufficient amount of K or Na is essential to initiate ASR; at low alkali concentrations C-S-H is stabilized instead. However, too high alkaline concentrations (≥900 mM at K(or Na)/Si ≥ 1) also favor C-S-H formation and suppress ASR product formation. The results reveal a strong effect of the alkalis (K and/or Na) on calcium concentrations and on the formation of ASR products; a maximum ASR product formation is observed at Na or K concentrations between 200 and 500 mM and at initial Ca/Si ratio between 0.1 and 0.4.

中文翻译：

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钾、钠、钙对碱硅反应产物形成的综合作用

摘要 碱和钙在碱-二氧化硅反应 (ASR) 产物的形成中都起着至关重要的作用。研究它们的组合效应有助于更好地了解 ASR 的状况。在本研究中，在 80 °C 下合成了具有恒定 Ca/Si 比为 0.3 但不同 K（或 Na）/Si 和 K/Na 比的样品。实验研究和热力学模型表明，足够量的 K 或 Na 对于启动 ASR 至关重要；在低碱浓度下，CSH 反而稳定了。然而，过高的碱性浓度（在 K（或 Na）/Si ≥ 1 时≥900 mM）也有利于 CSH 的形成并抑制 ASR 产物的形成。结果表明碱（K 和/或 Na）对钙浓度和 ASR 产物的形成有很强的影响；