压蒸条件下硅灰对矿渣水泥性能的优化作用

用纯硅酸盐水泥和磨细矿渣（比表面积６００ｍ３／ｋｇ）配成高含量矿渣水泥（矿渣６７．５％），以水灰比０．３２，掺１．５％萘系超塑化剂Ｍｉｇｈｔｙ－１５０拌成净浆。矿渣水泥净浆在１７５℃、１ＭＰａ条件下压蒸１ｄ以后强度大幅度下降，水泥孔结构粗化。如用７％硅灰取代磨细矿渣，矿渣水泥净浆强度在连续压蒸下不但不降而且不断上升，在１２５℃、１ＭＰａ压力下压蒸１４ｄ，强度可达１１４ＭＰａ。矿渣水泥在掺入硅灰以后，水泥液相的ｐＨ可望降至１２以下，因此这种水泥可以用来作ＧＲＣ的基材。硅灰的加入改变了矿渣水泥的水化反应和产物，使矿渣水泥强度下降的产物ａ－Ｃ２ＳＨ不再形成。用扫描水银测孔仪测定了硬化浆体的孔结构，结果表明，总孔隙率和最可几孔径在掺入硅灰后均明显减小，且随蒸养时间的增加而越来越小。

Cement pastes have been prepared at W/ C Of 0. 32 by using high slag content cement and Mighly-150 naphthalenebased superplasticizer at the dosage of 1. 5%. The high slag content cement is composed of PC and 67. 5% of finely ground slagwith the specific surface area of 600m2/kg. There exist a remarkable reduction in strength and coarsening in the pore structurefor the pastes autoclaved for id at 175t and 1MPa, while strength enhancement has been found for the pastes using 7% ofsilica fume as the replacement of slag. The strength can be as high as 114MPa when autoclaved for 14d under 125t and 1MPa.The alkalinity Of pore solution can be reduced below PH12 with the blending of silica fume into slag cement. The blended cementcan therefore be used to make GRC products. The addition of silica fume leads to certain change in the hydration process and thecomposition of hydrates, namely a -- CZSH which is a hydrate causing the reduction of strength does not form in the pastes. Thedetermination of the pore structure with MIP indicates that the total porosity and the most probable pore diameter decrease clearlyafter the addition of silica fume, and that they further decrease with the time of autoclave.