磷酸和两性季铵盐改性聚羧酸减水剂研究

Synthesis and performance of phosphate-modified and amphoteric quaternary ammonium salt-modified polycarboxylate superplasticizers used in cement paste

为研究不同电荷分布的减水剂对水泥浆体流动性能的影响,分别引入了磷酸基团和季铵盐合成了聚羧酸系减水剂PCE-P和PCE-N。利用红外光谱分析、流变仪和ζ电位手段表征,对水泥净浆流动度和保坍性能进行了测试。结果表明,制备的磷酸改性的共聚物在相同的水灰比和掺量下与水泥颗粒的表面正电荷具有较强的静电吸附作用,在掺入质量分数为0.2%时,流动度可达到287 mm,并且在120 min内仍可以保持流动度在280 mm以上,而普通的减水剂在40 min之后浆体流动度就会损失至180 mm。分散性能显著优于普通的聚羧酸系减水剂。

The charge characteristics of the polycarboxylate superplasticizers(PCEs)have a strong impact on the dispersion properties of the cement pastes.Here in this article,we introduced phosphonic group and positive group(C≡N+)respectively into polycarboxylate-like copolymers to study how they influence the property of cement pastes,and the copolymers were prepared via free-radical copolymerization.The chemical structure of the polymers and workability of cement pastes were characterized by series measurements,showing that phosphate comb polymers possessed a much higher adsorption affinity to surface of cement particles at the same w/c ratio and dosage.The phosphate copolymers also exhibited superior dispersion and more excellent workability when compared to conventional polycarboxylates and amphoteric copolymers.When cement was added with 0.2%phosphate copolymers,the degree of fluidity could reach 287 mm,and remaining 280 mm within 120 min,comparing with normal water reducing admixture which fluidity degree would decrease below 180 mm within 40 min.This research offered a promising alternative,and laid the foundation for their industrial application.