不同温湿度下丁苯乳液/硫铝酸盐水泥砂浆的干缩率

Dry Shrinkage Rate of Styrene Butadiene Copolymer Dispersion/Calcium Sulphoaluminate Cement Mortar under Different Curing Temperature and Humidity

关键词:  温度  湿度  丁苯乳液  硫铝酸盐水泥砂浆  干缩率

Key words:  temperature  humidity  styrene butadiene copolymer dispersion  calcium sulphoaluminate cement mortar  dry shrinkage rate

摘要:

采用丁苯乳液改性硫铝酸盐水泥砂浆，研究了不同温湿度养护条件（温度包括0，5，10，20，40℃，相对湿度RH包括30%，60%，90%)对丁苯乳液/硫铝酸盐水泥砂浆360 d内干燥收缩性能的影响.结果表明：不同温湿度下，掺入5%（质量分数，下同）丁苯乳液均会增大硫铝酸盐水泥砂浆的干缩率，但当丁苯乳液掺量达到10%后，砂浆干缩率会随着丁苯乳液掺量的增加而显著降低0℃养护时，砂浆干缩率均较小，随着养护温度的提高，砂浆干缩率增大；10℃养护时，砂浆干缩率达到最大（丁苯乳液掺量为5%时，养护28d后在20℃时砂浆干缩率达到最大）；20℃养护时，砂浆干缩率有所减小，但仍高于0℃和5℃养护时的干缩率；40℃养护时，基准砂浆早期产生了微膨胀，但改性砂浆则未产生.不同龄期下，高温（40℃）养护砂浆的干缩率要低于低温（0，5℃）养护时.提高相对湿度会降低砂浆干缩率，且龄期越长，作用效果越显著.

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.