不同长度侧链的梳状结构聚羧酸盐的合成及其对新拌水泥浆体性能的影响

Synthesis of Polycarboxylate with Different Comb Structures and It's Influence on Properties of Fresh Cement Pastes

通过自由基聚合反应合成了3组主链聚合度基本相同、侧链长度不同的梳状结构聚羧酸盐,对其表面张力和对水泥浆体流动性的影响进行了测试,并研究了其对硅酸盐水泥及添加不同品种和掺量的辅助性胶凝材料的水泥浆体的液相表面张力、流动性及Zeta电位的影响。结果表明:其它实验条件不变、主链聚合度相同的情况下异戊烯醇聚氧乙烯醚(TPEG)与α-甲基丙烯酸(α-MAA)的摩尔比从1:1增加到5:1,合成的聚羧酸盐的表面张力从47.70 m N/m降低至35.53 m N/m,添加到水泥净浆中时初始流动度从280 mm增大至310 mm;随着辅助性胶凝材料和聚羧酸减水剂掺量的增加,水泥浆体的液相表面张力减小、流动性增强;当水胶比从0.5降到0.3,水泥浆的Zeta电位呈现上升趋势,浆体稠度变大,Zeta电位变化更明显;水胶比为0.3时,水泥浆体的Zeta电位值随着辅助性胶凝材料和聚羧酸减水剂掺量的增加呈现下降趋势。

Three polycarboxylates with different comb structures(i.e., the same degree of polymerization in main chains and different side chains) were synthesized via radical polymerization reaction. The effect of polycarboxylates on the surface tension and the fluidity in cement pastes was determined. The effect of polycarboxylates on the surface tension of liquid, the fluidity, and Zeta potential of cement pastes with different kinds and contents of mineral admixture were also investigated. The results show that the surface tension of polycarboxylate decreases from 47.70 m N/m to 35.53 m N/m and the paste fluidity increases from 280 mm to 310 mm with increasing the molar ratio between isoamyl alcohol polyoxyethylene(TPEG) and α-methacrylate(α-MAA) from 1:1 to 5:1. The liquid surface tension of cement pastes decreases and the paste fluidity increases with increasing the dosage of supplementary cementitious materials and polycarboxylate. As the water-cement ratio decreases from 0.5 to 0.3, the Zeta potential of cement pastes increases. When the water-cement ratio is 0.3, the Zeta potential decreases with increasing the dosage of supplementary cementitious materials and polycarboxylate.