Abstract:Calcium sulphoaluminate(CSA) cement mortar was modified with styrene butadiene copolymer(SB) dispersion and its dry shrinkage rates within 360 days under different curing humidities(30%, 60%,90%) and temperatures(0, 5, 10, 20,40℃) were investigated. The results show that the dry shrinkage rate of CSA cement mortar increases with 5%(by mass, the same below) SB added, but it decreases significantly with the increase of SB content when the SB content is more than 10% in all curing temperature and humidity conditions. The dry shrinkage rate of mortar is small at 0℃, but it increases with the increase of the curing temperature. The dry shrinkage rate of mortar reaches maximum at 10℃(20℃ with 5% SB, 28d). Then it decreases at 20℃ but it is still higher than that at 0℃ and 5℃. The reference mortar expands at 40℃ in early ages, whereas the modified mortar does not. The dry shrinkage rate of mortar at high curing temperature(40℃) is lower than that at low curing temperature(0℃) in all ages. The dry shrinkage rate is also reduced by increasing humidity, and the effect is more significant with the increase of curing age.