聚羧酸系减水剂对水泥砂浆塑性毛细管负压的影响研究

The Influence of Polycarboxylate Superplasticizer on Capillary Depression of Cement Mortar at Plastic Stage

主要研究了不同类型聚羧酸系减水剂对水泥砂浆塑阶段性毛细管负压发展的影响。试验结果表明,保坍型和超保坍型聚羧酸减水剂不仅对砂浆流动度损失性能改善明显,而且对砂浆塑性阶段毛细管负压增长速率也有减缓作用。对于C30混凝土筛出的低强度等级水泥砂浆,保坍型聚羧酸减水剂相对于减水型聚羧酸减水剂能延缓自由水释放,有效降低砂浆初凝前塑性阶段毛细管负压的增长速率,降低砂浆塑性开裂风险。对于C50混凝土筛出的高强度等级水泥砂浆,超长保坍聚羧酸减水剂降低砂浆初凝前塑性阶段毛细管负压的增长速率有限,与缓凝剂配合可实现有效控制砂浆塑性开裂。

The influence of different types of polycarboxylate superplasticizer on the development of the cement mortar capillary depression at plastic stage was studied.The experimental results show that the polycarboxylate superplasticizer with keeping slump and the super keeping slumps not only improve the performance of mortar fluidity loss,but also slow down the mortar plastic capillary depression growth rate.For the cement mortar of low grade screened out from the C30 concrete,compared the polycarboxylate superplasticizer with water reducing with the polycarboxylate superplasticizer with keeping slump can release free water effectively and reduce mortar plastic capillary depression growth rate before initial setting mortar,and reduce the risk of mortar plastic cracking.For the cement mortar of the high grade screened out from the C50 concrete,the polycarboxylate superplasticizer with super keeping slumps reduces mortar plastic capillary depression growth rate before initial setting mortar is limited,and the combination of retarder can effectively control the risk of mortar plastic cracking.