Drying shrinkage process of hardened high tricalcium silicate cement mortar

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°C. The results show that high C₃S cement mortar is in the distinct shrinkage stage at the age of 3-60 d. 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.