聚羧酸系减水剂的分散作用及其引气性能(英文)

DISPERSIBILITY AND AIR ENTRAINING PERFORMANCE OF POLYCARBOXYLATE-TYPE WATER REDUCERS

采用自由基聚合法合成了一系列聚羧酸减水剂,通过正交试验研究了减水剂官能团种类及比例,引发剂、链转移剂对其在水泥浆中分散性能的影响。在此基础上,通过优化官能团比例及调整分子量合成了一种引气性低且分散性高的聚羧酸系减水剂。分析了官能团比例和分子量对聚羧酸系减水剂引气性能的影响,探讨了分子量及其分布与聚羧酸系减水剂的分散性能及其饱和掺量的关系。结果表明:合适的官能团比例是降低聚羧酸系减水剂引气性的前提。官能团比例合适时,分子量过高将导致其引气性增强,聚羧酸系减水剂在水泥净浆中的分散性低,且在水泥砂浆中的饱和掺量高。

A series of polycarboxylate-type water reducers （PCWRs） were synthesized by free radical copolymerization. Effects of type and ratio of the functional group, initiator and chain transfer on the dispersibility of the PCWRs in cement grout were investigated by using an orthogonal test. The PCWR with a low air entraining capability and a high dispersibility was synthesized by optimizing the functional group ratio and adjusting the molecular mass. The effects of the functional group ratio and the molecular mass on the air entraining performance of the PCWR were analyzed. The relationships among the molecular mass and its distribution and the dispersibility, as well as the saturation dosage of the PCWRs were discussed. The results show that. The strengthened air entraining capability of the PCWR with the appropriate functional group ratio results from the excessively high molecular mass. When the molecular mass is excessively high, the dispersibility of the PCWR in the cement paste is low, but its saturation dosage in cement mortar is high.