聚羧酸系减水剂的吸附分散行为研究

摘要

通过合理的假设预测了聚羧酸系减水剂(PC)在水泥颗粒表面的吸附形态，并采用超滤膜法将自制PC分离成四种不同分子量范围的分离组分F1（平均分子量为10万以上），F2（5万至10万），F3（1万至5万），F4（1万以下），通过有机碳总分析法及净浆流动度表征了该PC/分离组分的吸附量以及对水泥浆体的分散性。研究结论显示：PC分子呈卷曲状吸附于颗粒的表面，而非直线型，而且随掺量的增加这种卷曲程度逐渐增大；各分离液/PC对基准水泥浆体的分散性大小顺序为：F2＞F1＞PC0＞F3＞F4；PC在水泥颗粒表面吸附过程属于分级吸附，其中分子量较小的减水剂分子首先吸附到水泥颗粒的表面，而后是分子量较大的分子。%Polycarboxylic superplasticizer's absorbent morphology on the surface of cement particles is forecasted through reasonable assumption, and ul-trafiltration membrane method is applied to separate polycarboxylic superplasticizer into four kinds of components (F1, F2, F3, F4) in different molecular weight ranges. Organic carbon total analysis and cement paste fluidity demonstrate this PC/ separated components' absorbent capacity and dispersion per-formance on cement pastes. It could be concluded that the order of all separated liquids/polycarboxylic superplasticizer's dispersion performance follow the rule as F2>F1>PC0>F3>F4. PC's absorbing process on the surface of cement particles is classification absorption, while water reducing agents with smaller molecular weight absorbed on the surface of cement particles first, then the agents with larger molecular weight.