CO2预养护加气混凝土中碳酸钙结晶的形态特征,RSC Advances

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CO2预养护加气混凝土中碳酸钙结晶的形态特征
RSC Advances ( IF 3.9 ) Pub Date : 2022-05-13 , DOI: 10.1039/d2ra01901a
Jiayu Lu ₁ , Shengqian Ruan ₁ , Yi Liu ₂ , Tao Wang ₃ , Qiang Zeng ₁ , Dongming Yan ₁

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碱性建筑材料（如水泥混凝土）的早期CO _{2固化技术由于材料性能改善和CO}₂沉降潜力大等优点而受到越来越多的关注。然而，较少关注碳酸化水泥混凝土中CaCO _{3的形态特征。}研究了在 0.1、1和 2 bar 的CO ₂气体压力下养护的早龄加气混凝土 (AC)中 CaCO _{3的晶体结构和微观形态。}制造的 AC 具有高 CO ₂吸附能力（在 100 mm 立方体中每 100 g 水泥约35 g CO _{2 ）。}_{CaCO 3}的形态特征对长轴长度（b）、短轴长度（a）和纵横比（K = b / a）进行了统计分析。随着 CO ₂压力的增加，b从 0.8 到 1.8 μm 几乎没有变化，a从 0.7 减小到 0.4 μm，因此，K从 1.3 增加到 2.5。AC中不同的CaCO ₃晶体形态归因于CO ₂压力相关的晶体转变过程：低气压诱导对称的CaCO ₃生长，而高气压导致晶体尖端的方解石生长更快。该发现将加深对不同CO ₂固化压力下CaCO ₃晶体形成的理解，以调整CO ₂固化水泥混凝土的微观结构。

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Morphological characteristics of calcium carbonate crystallization in CO2 pre-cured aerated concrete

Early-stage CO₂ curing technology for alkaline construction materials (such as cement concrete) has gained increasing interest owing to the advantages of material properties improvement and high potential of CO₂ sinking. Less attention, however, has been paid to morphological characteristics of CaCO₃ in carbonated cement concrete. The crystal structure and micromorphology of CaCO₃ in an early-age aerated concrete (AC) cured under CO₂ gas pressures of 0.1, 1, and 2 bar were investigated. The fabricated AC has a high CO₂ sorption capacity (∼35 g CO₂ per 100 g cement in a 100 mm cube). The morphological characteristics of CaCO₃ were statistically analyzed in terms of long-axis length (b), short-axis length (a), and aspect ratio (K = b/a). As CO₂ pressure increases, b is almost unchanged from 0.8–1.8 μm, a decreases from 0.7 to 0.4 μm, and, consequently, K increases from 1.3 to 2.5. The different CaCO₃ crystal morphologies in AC are ascribed to the CO₂ pressure-associated crystal transformation processes: low gas pressure induces a symmetric CaCO₃ growth, while high gas pressure causes a faster calcite growth at the crystal tip ends. The findings would deepen the understanding of CaCO₃ crystal formation under different CO₂ curing pressures for tuning the microstructure of CO₂-cured cement concrete.

更新日期：2022-05-13

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