Calcium silicate minerals can react with CO₂ to form calcium carbonate and have been proposed to be a sustainable binder as a potential CO₂ sinker. In this study, the carbonation characteristics are comparatively assessed among calcium silicates having different calcium/silica (Ca/Si) ratios and polymorphs (CS, C₃S₂, γ-C₂S, β-C₂S, C₃S). Calcium silicate compacts exposed to a 100% CO₂ environment at a 0.4 MPa pressure were tested for carbonation temperature evolution, degree of carbonation (DOC), mechanical properties, and microstructural characterization. Results indicate γ-C₂S is the most reactive, reaching a DOC of 50% in 24 h, followed by C₃S₂, CS, β-C₂S, and C₃S, which generally agrees with the pattern of the cumulative normalized temperature increase. Meanwhile, carbonated β-C₂S compact attains the highest compressive strength of 80 MPa in 24 h, followed by γ-C₂S, C₃S₂, and C₃S, while CS only reaches 20 MPa. Calcite and aragonite are the preferable polymorphs of calcium carbonate in the carbonated C₃S, γ-C₂S, β-C₂S, and C₃S₂, while only the carbonation of CS generates vaterite in addition to calcite and aragonite. The unreacted grains coated by a thin rim of calcium-modified silica gels are encapsulated by the continuous calcium carbonates, which composes the skeleton of the carbonated calcium silicates.

中文翻译：

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碳酸活化硅酸钙作为可持续粘合剂的比较研究：反应性，机械性能和微观结构

硅酸钙矿物可以与CO ₂反应形成碳酸钙，并且已被提议作为可持续的粘结剂作为潜在的CO ₂沉降物。在这项研究中，碳酸化特性相对钙硅酸盐中评估具有不同钙/二氧化硅（钙/ Si）的比和多晶型物（CS，C ₃小号₂，γ-C ₂ S，β-C ₂ S，C ₃ S） 。测试了在0.4 MPa压力下暴露于100％CO ₂环境的硅酸钙压块的碳化温度演变，碳化程度（DOC），机械性能和微观结构表征。结果表明γ-C ₂S是最具反应性的，达到了50％的在24小时DOC，接着为C ₃小号₂，CS，β-C ₂ S，和C ₃ S，其通常同意的累积归一化温度增加的图案。另一方面，碳酸β-C ₂的紧凑型在无所获24小时80兆帕的最高压缩强度，接着γ-C ₂ S，C ₃小号₂，和C ₃ S，而只CS达到20兆帕。方解石和文石是在碳酸Ç碳酸钙的优选多晶型物₃ S，γ-C ₂ S，β-C ₂ S，和C ₃小号₂，而除了方解石和文石之外，仅CS的碳化会生成球ate石。连续的碳酸钙包封了薄薄的钙改性硅胶边缘所覆盖的未反应颗粒，碳酸钙构成了碳酸硅酸钙的骨架。