碱-矿渣水泥浆体的碳化过程研究

Study on carbonation process of alkali-activated slag cement pastes

针对碱-矿渣水泥水化产物中不存在Ca(OH)2且碳化比较严重的现象,选择水玻璃和NaOH作碱组分,采用X-射线衍射仪和可变真空扫描电子电镜研究了碱-矿渣水泥浆体的碳化产物和微观形貌,结合氮吸附方法分析了碳化对碱-矿渣水泥浆体孔结构的影响.结果表明:碱-矿渣水泥浆体的碳化是CO2直接和水化硅酸钙(C-S-H)凝胶发生作用的结果,碳化后生成的碳酸钙主要以方解石的形式存在;碳化后,C-S-H凝胶的Ca与Si原子比降低,浆体的比表面积增大,平均孔径降低,而累积孔体积的变化情况和碱组分有关.

As there is no Ca（OH）2 in the hydration products of alkali-activated slag cement, and its carbonation is serious, water glass and NaOH were selected as the alkali activater, and X-ray diffraction （XRD） and scanning electron microscope （SEM） were adopted to study the carbonation and structure of alkali-activated slag cement, while the pore structure was researched by Nitrogen adsorption. The results show that the carbonation takes place directly on the C-S-H gel and calcium carbonate, the carbonated product of alkali-activated slag pastes, existing mainly in the form of calcite. After carbonation, the Ca/Si of C-S-H gel decreases, while specific surface area of the pastes increases and the average pore diameter reduces. The change in cumulative volume of pores varies with the alka-li activater.