Limited information about the atomic structure of amorphous and nanocrystalline alkali–silica reaction (ASR) products is available. Here, reactive molecular simulations were employed to construct a model of these products based on defective shlykovite. To introduce disorder into the models, various annealing temperatures (ranging from ambient to temperatures above silicate dissolution) were tested. Structures obtained from annealing at 700 K reproduced the main peaks observed experimentally in X-ray diffraction patterns of “ASR-P1” phase, a nanocrystalline or amorphous alkali–silica reaction product recently identified in synthetic and field concrete. Pair distribution functions and structure factors computed for this structure also compared well with previous data reported for “amorphous” ASR products. These results demonstrate that what was previously considered “amorphous” ASR products might be related to nanocrystalline defective shlykovite structures.

中文翻译：

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纳米晶和非晶ASR产品的原子结构


关于非晶态和纳米晶碱硅反应 (ASR) 产品原子结构的信息有限。在这里，采用反应分子模拟来构建基于缺陷什利科维特的这些产品的模型。为了将无序引入模型，测试了各种退火温度（从环境温度到高于硅酸盐溶解的温度）。 700 K 退火获得的结构再现了在“ASR-P1”相的 X 射线衍射图中实验观察到的主峰，“ASR-P1”相是最近在合成混凝土和现场混凝土中发现的纳米晶或无定形碱-二氧化硅反应产物。针对该结构计算的对分布函数和结构因子也与之前报告的“非晶”ASR 产品数据进行了很好的比较。这些结果表明，以前被认为是“无定形”的 ASR 产品可能与纳米晶缺陷什利科维特结构有关。