含不同官能团聚羧酸减水剂的吸附分散性能

Adsorption and Dispersing Capability of Polycarboxylate Superplasticizers with Various Functional Groups

摘要:

通过水溶液自由基聚合法合成了含有不同官能团的聚羧酸减水剂，并研究了不同结构聚羧酸减水剂的吸附分散性能，以及其对水泥水化性能的影响.结果表明：含酰胺基的聚羧酸减水剂对水泥浆体流动度的削弱程度最大，含酯基官能团的聚羧酸减水剂对水泥浆体流动度的影响程度较小.含磺酸基团的聚羧酸减水剂吸附性能增强；而含酰胺基及酯基的聚羧酸减水剂的吸附性能削弱.含酯基官能团的聚羧酸减水剂显著延缓了水泥水化诱导期，相比之下，含磺酸基官能团的聚羧酸减水剂提高了水泥水化加速期的最大水化放热速率.

Abstract:

A series of polycarboxylate superplasticizers (PCEs) with different functional groups were synthesized through free radical polymerization. The adsorption behavior as well as dispersing capability of these PCEs was investigated. In addition, the effects of these PCEs on cement hydration process were systematically studied through isothermal calarimetry and Xray diffraction(XRD). The results show that PCE with acylamino groups most significantly depresses the dispersing capability due to highly decreased adsorption amount on cement particles, while PCEs with ester function groups rarely influence the dispersing capability. PCEs with sulfonic groups exhibit enhanced adsorption behavior. The introduction of ester groups or AMPS into PCE backbones remarkably hinders the induction period of cement paste, in comparison with reference PCE (P(PEG1AA4)) (the molar ratio of side chains to negative ions is 1:4), while the introduction of sulfonic groups into PCE molecules improves the maximum hydration heat evolution rate at acceleration period. At early ages, PCEs inplanted with sufonic groups, acylamino groups, or ester groups promotes the hydration process in comparison with reference PCEs (P(PEG1AA4)). However, at 28 days, cement paste added with reference PCE (P(PEG1AA4)) exceeds that with other PCEs in cement hydration degree.