The influence of mineral admixtures on sulfate resistance of limestone cement pastes aged in cold MgSO_4 solution

摘要

The influence of slag (S), fly ash (FA)and silica fume (SF) on the sulfate resistance of limestone cements was evaluated. Hardened pastes were exposed to MgSO_4 solution at 5 deg C. Visible changes of the samples during the exposure were followed. Absorption of sulfate was measured and changes in mineralogical composition were evaluated by thermogravimetric analysis and X-ray diffraction (XRD). It was fund that among admixtures used, only the addition of silica fume to limestone cement significantly improved its sulfate resistance. Cement with lower contents of C_3A and C_3S also showed favorable performance compared to cement having higher contents of these minerals.