降黏型聚羧酸减水剂的制备与应用研究

Preparation and application of viscosity-reducing polycarboxylic acid water reducer

以低分子质量乙烯醚类(2+2型)乙二醇单乙烯基聚乙二醇(EPEG)为大单体,甲基丙烯基酒石酸(单酯)为小单体,巯基乙醇为链转移剂,在双氧水和维生素C构成的氧化还原体系中与丙烯酸发生自由基聚合反应,制得一种降黏型聚羧酸减水剂PC-D。通过正交试验和单因素试验,得到其最佳反应工艺参数为:酸醚比5,链转移剂、甲基丙烯基酒石酸(单酯)和引发剂用量分别为大单体质量的0.35%、14%和5.5%,滴加时间为1 h。在高强混凝土中,PC-D与相同折固掺量下的市售降黏型聚羧酸减水剂PC-Q、PC-M相比,混凝土和易性得到明显改善,混凝土经时1 h排空时间变化分别减小了20.5%、28.2%。PC-D已在绿地山东国际金融中心工程中得到成功应用。

A kind of viscosity-reducing polycarboxylic acid water reducer PC-D was prepared through free radical polymeriza-tion occurs with acrylic acid in the redox system composed of hydrogen peroxide and vitamin C using low molecular weight ethy-lene glycol ether type 2 +2 big monomer vinyl single polyethylene glycol(EPEG) as the macromonomer,methyl allyl tartaric acid(monoester)as small monomer,mercaptoethanol as chain transfer agent. Through orthogonal test and single factor test,the optimum reaction conditions were obtained as follows:acid to ether ratio 5,the amount of chain transfer agent,methylpropenyl tartaric acid(monoester) and initiator were 0.35%,14% and 5.5 of the mass of macromonomer,respectively,the doping time is 1 h. Polycarboxylic acid water reducer PC-D in high strength concrete can shorten the emptying time of high strength concrete by 20.5% and28.2%,compared with viscosity reducing superplasticizer PC-Q and PC-M with the same folding content,and the workability of high strength concrete was obviously improved. The polycarboxylic acid water reducer PC-D has been successfully applied in the green Shandong International Financial Center project.