外加剂对聚合物改性水泥砂浆凝结时间的影响

Effect of Admixtures on Setting Time of Polymer Modified Cement Mortar

通过系统试验，研究了聚合物改性剂、硅烷偶联剂、减缩剂及消泡剂对聚合物改性水泥砂浆凝结时间的影响。发现聚灰比（聚合物水泥含量比）与偶联剂、减缩剂及消泡剂掺量均对水泥砂浆的凝结时间影响显著：聚合物改性水泥砂浆的凝结时间较普通水泥砂浆有所延长，且随着聚灰比的增加而增大，但增长程度越来越小；随着3种外加剂掺量的增加凝结时间均表现出增大的现象，但增长速率随聚灰比的增加而减弱，聚灰比的影响程度高于外加剂；无水酒精作为偶联剂稀释剂时使聚合物改性水泥砂浆凝结时间顺延程度加剧。从凝结时间考虑，最优的聚合物和外加剂掺量如下：聚灰比0．1，消泡剂3‰，偶联剂为3‰，减缩剂宜≤2％。最后对以上3种外加剂的作用机理做了探讨。

An experimental study on the relativity between polymer cement ratio, silence coupling agent, defoamer, shrinkage reducing admixture and the setting time of polymer modified cement mortar was carried out. The results show that the influence of polymer cement ratio, coupling agent, defoamer and shrinkage reducing admixture content on the setting time is significant. Compared with ordinary cement mortar, the setting time of polymer cement mortar was extended, and increased with the polymer cement ratio increase, but the increase rate was more and more slow. The setting time increased with the contents of the three kinds of admixtures increase, but the increase rate decreased with the polymer cement ratio increase. The influence of polymer cement ratio was more than admixtures. Anhydrous alcohol used as the diluting agent for coupling agent intensified the setting time extension of polymer modified cement mortar. Considering the setting time, the optimal amount of polymer and admixtures as follow： the polymer cement ratio was 0.1, defoamer content was 3‰, coupling agent content was 3‰, shrinkage reducing admixture content should not be greater than 2%.The mechanism of action of these three kinds of admixtures was discussed.