混凝土用磷酸基缓凝剂的制备与性能研究

Preparation and Properties of Phosphate Retarders for Concrete

以尿素为底物合成了一种新型的磷酸基缓凝剂(UEP),通过对反应条件的优化确定了最优的合成条件:尿素、浓硫酸、亚磷酸、甲醛的摩尔比为1∶1∶4∶4. 4,反应温度为120℃,反应时长为24 h。与市售缓凝剂HEDP、EDTMPS进行了净浆中性能的对比分析、水化热及混凝土性能测试发现,几种样品均符合国标要求,缓凝能力EDTMPS>UEP>HEDP,UEP样品水化热出峰靠后但放热量高,可能是造成其在净浆中初始流动性好,而缓凝效果稍差于EDTMPS的原因。

A new phosphoric acid-based retarder(UEP)was synthesized with urea as substrate.And the optimum synthesis conditions were determined by optimizing.The molar ratio of urea,sulfuric acid,phosphorous acid,formaldehyde was 1:1:4:4.4,the reaction temperature was 120℃,and the reaction time was 24 h.The hydration heat test and the concrete performance test were used to determine the excellent performance of the synthesized retarder comparing with the HEDP and EDTMPS.It was found that all the samples met the national standard,the retarding capacity was EDTMPS>UEP>HEDP.The delayed peak of UEP samples but high heat release may be the reason that the initial fluidity of UEP sample was better than that of EDTMPS,but the retarding effect was slightly worse.