Amorphous calcium (alumino) silicates are the main component of industrial byproducts (e.g., blast furnace slag and fly ash) and can be generated by grinding silicate minerals that are abundant in steel slag and carbonated calcium silicate binders. To promote the production of CO2-activated building material from diverse materials, this study investigated the carbonation of synthetic calcium silicate glasses, model compounds of these amorphous silicates. A dissolution-controlled carbonation mechanism was revealed, in contrast with a nucleation-controlled counterpart for the carbonation of wollastonite, a model compound of silicate minerals. The former mechanism is governed by the number of Q3 species in the silica layers on carbonated particle surfaces serving as sites for ionic exchange. The latter is evidenced by well-aligned CaCO3 nuclei precipitating on wollastonite particles under high CaCO3 supersaturation. Overall, high Ca/Si ratios favor carbonation. At Ca/Si = 1, the calcium silicate glass shows faster carbonation kinetics than wollastonite at early ages.

中文翻译：

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硅酸钙玻璃在不同钙硅酸盐比例下的碳化反应性以及与硅灰石的比较


无定形硅酸钙（铝）是工业副产品（例如高炉渣和粉煤灰）的主要成分，可以通过研磨钢渣和碳酸硅酸钙粘合剂中丰富的硅酸盐矿物来生成。为了促进从各种材料中生产 CO2 活化建筑材料，本研究调查了合成硅酸钙玻璃的碳化，这些无定形硅酸盐的模型化合物。揭示了一种溶解控制的碳化机制，与硅酸盐矿物的模型化合物硅灰石碳化的成核控制机制形成鲜明对比。前一种机制由作为离子交换位点的碳酸盐颗粒表面二氧化硅层中 Q3 物质的数量控制。后者表现为在高 CaCO3 过饱和度下，排列良好的 CaCO3 核沉淀在硅灰石颗粒上。总体而言，高 Ca/Si 比率有利于碳化。在 Ca/Si = 1 时，硅酸钙玻璃在早期表现出比硅灰石更快的碳化动力学。