碳化对碱矿渣水泥浆体微观结构的影响

Influence of Carbonation on Microstructure of Alkali-Activated Slag Cement Pastes

针对碱-矿渣水泥水化产物中不存在Ca(OH2)且碳化比较严重的现象,选择水玻璃作为碱组分,采用X-射线衍射(XRD)和可变真空扫描电子电镜(SEM)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-矿渣水泥浆体碳化导致的孔隙溶液Ca2+浓度降低由水化硅酸钙(C-S-H)凝胶脱钙补偿,碳化生成的碳酸钙主要以方解石的形式存在;碳化后,C-S-H凝胶的钙硅比降低,浆体的比表面积增大,平均孔径降低,而累积孔体积的变化与水玻璃的模数有关.

In view of the phenomena that no Ca（OH）2 exsits in the hydration products of alkali-slag cement and its carbonation is more serious, water glass was selected as the alkali activater, and XRD and SEM were adopted to study carbonation products and microstructure of alkali-slag cement pastes, 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-slag pastes exists mainly in the form of calcite. After carbonation, the Ca/Si of C-S-H gel decreases, while surface area of the pastes in- creases and the average pore diameter reduces. The change in cumulative volume of pores varies with mo- dulus of water glass.