高硅酸三钙水泥硬化砂浆干缩过程

DRYING SHRINKAGE PROCESS OF HARDENED HIGH TRICALCIUM SILICATE CEMENT MORTAR

通过测定高硅酸三钙(C3S)水泥砂浆在20℃两种相对湿度(RH40%,RH50%)下的干缩曲线,研究了该水泥砂浆的干缩动力学及干缩过程,揭示了该水泥砂浆干燥收缩过程的演变规律。结果表明高C3S水泥砂浆在3～60d的收缩阶段,其收缩速率不同,可分为3个阶段:收缩速率较快的收缩减速阶段;收缩速率较慢的收缩减速阶段和收缩速率几乎不变的稳态收缩阶段。提出了高C3S水泥系统的干燥收缩过程假设:3～14d,主要是相对蒸汽压较高且孔径较大的孔失水导致收缩;14～28d,主要是相对蒸汽压较小且孔径较小的孔失水导致收缩;28～60d,则主要是水泥石失去凝胶吸附结合水导致收缩。

The drying shrinkage dynamics and drying shrinkage process of high C3S cement mortar were studied according to its drying shrinkage curves tested at two drying condition of RH 50% and RH 40% at 20 ℃. The results show that high C3S cement mortar is in the distinct shrinkage stage at the age of 3-60d. According to shrinkage rate, the shrinkage stage can be divided into 3 stages： a shrinkage slowdown stage at a faster shrinkage rate; a shrinkage slowdown stage at a slower shrinkage rate; and a stage at a constant rate. The drying shrinkage processes are as follows： at the age of 3-14 d, shrinkage mainly due to moisture loss from the bigger pores which have higher relative vapor pressure; at the age of 14-28 d, shrinkage mainly due to moisture loss from the smaller pores which have lower relative vapor pressure; at the age of 28-60 d, shrinkage mainly due to loss of adoption water of gels in cement stone.