高掺量橡胶集料水泥砂浆收缩性能研究

Shrinkage Performance of Cement Mortar with High Content of Rubber Aggregate

为研究高掺量橡胶粉与膨胀剂对水泥砂浆收缩性能的影响,在水泥砂浆中分别单掺10%、20%、30%(体积分数)的20目(0.83 mm)、50目(0.27 mm)橡胶粉和4%、7%、10%(质量分数)的膨胀剂,在此基础上进行正交试验,测试复掺橡胶粉及膨胀剂砂浆的自由收缩性能。结果表明:单掺时,水泥砂浆的自由收缩率随橡胶粉粒径减小、掺量增大而减小;20目橡胶粉掺量在30%、50目橡胶粉掺量大于10%、膨胀剂掺量为4%时,自由收缩率显著降低;复掺时,影响自由收缩的主要因素是橡胶粉;28 d前膨胀剂对自由收缩的影响较为明显,高掺量橡胶粉补偿后期收缩的作用显著,且对同期膨胀剂有一定促进作用;膨胀剂发挥最佳补偿收缩作用的掺量为2%,这一结果为膨胀剂在干旱地区橡胶砂浆中的应用提供了依据。

In order to study the effects of high content of rubber powder and expansion agent on the shrinkage performance of cement mortar,10%,20%,30%(volume fraction)20 mesh(0.83 mm),50 mesh(0.27 mm)rubber powder and 4%,7%,10%(mass fraction)expansion agent were added into the cement mortar.On this basis,the orthogonal test was carried out to measure the free shrinkage performance of mortar mixed with rubber powder and expansion agent.The results show that the free shrinkage rate of cement mortar decreases with the decrease of rubber particle size and the increase of rubber powder content.When the content of 20 mesh rubber powder is 30%,the content of 50 mesh rubber powder is more than 10%,and the content of expansion agent is 4%,the free shrinkage rate decreases significantly.When compounded,the main factor affecting the free shrinkage is rubber powder.The effect of expansion agent on free shrinkage is obvious before 28,and the effect of high content of rubber powder on compensating the later shrinkage is significant,and it also promotes the expansion agent at the same time.The optimal content of expansion agent for compensating shrinkage is 2%,which provides a basis for the application of expansion agent in rubber mortar in arid areas.