Synthesis And Properties Of Ether-Type Polycarboxylate Superplasticizer

As concrete admixtures, polycarboxylate superplasticizers exhibit some excellent abilities of water-reducing, dispersion, slump retention, improving the strength of concrete, reducing the cement usage, etc. Therefore, the research and development of new polycarboxylate superplasticizers with more excellent performance and effective cost have an important practical significance, which is also the development trend of high performance superplasticizer in the future. In this dissertation, a series of ether-type and modified ether polycarboxylate superplasticizer had been synthesized and their properties were investigated.In this thesis, two kinds of ether-type polycarboxylate superplasticizers abbreviated as EPC and HEPC were respectively synthesized firstly via aqueous solution copolymerization of allyl polyoxyethylene ether monomer (APEG) or methyl alkenyl polyoxyethylene polyoxypropylene ether (VPEG), which acted as active macromonomer and selected monomers, in the presence of the chain transfer agent and initiator. The reaction conditions were optimized by single factor and orthogonal experimental design, in which cement initial and long-term paste fluidity was used as the measure indices. The optimized EPC and HEPC product was tested for adaptability of cement and concrete properties. The results showed that the cement paste fluidity of EPC had a large loss in the condition of W/C at0.35and the addition amount of0.3%. However, the cement paste fluidity of HEPC were maintained without any loss in the condition of W/C at0.29and the addition amount of0.2%, and HEPC exhibited an excellent adaptability of different cements. The EPC and HEPC water-reducing rate of concrete was respectively up to10%and30%. Compressive strength of concrete of HEPC for each age increased by more than220%after3days, which was significantly superior to that of EPC. Therefore, the EPC is a common ether-type polycarboxylate superplasticizer, while the HEPC is a high performance ether-type polycarboxylate superplasticizer.The APEG modified method:(1) the new ether-type polycarboxylate superplasticizer (CEPC) were synthesized in aqueous solution via copolymerization of monomers and butyl-terminated APEG, which was prepared from APEG and1-bromobutane;(2) a new amphoteric polycarboxylate superplasticizer (AEPC) was prepared for the first time in aqueous solution via copolymerization of monomers and cationic modified APEG, which was synthesized from APEG and2,3-epoxypropyltrimethylammonium chloride. The cationic modified APEG was characterized by infrared spectroscopy (FT-IR). With double bond retention and cement paste fluidity as the measure indices, the modified reaction conditions had been optimized, and the optimized products of CEPC and AEPC were tested for adaptability of cement and concrete properties. The results showed that compared with EPC, long-term(30min) cement paste fluidity of CEPC increased, while its initial (0min) cement paste fluidity declined slightly. Compared with EPC and CEPC, cement adaptability of AEPC was more excellent. Its concrete water-reducing rate was up to15%and compressive strength of concrete for each age increased by more than70%after3days. It can be a highly effective polycarboxylate superplasticizer.In this dissertation, in order to further enhance the performance of product applications, the complex of ether-type polycarboxylate superplasticizers and retarders had been studied systematacially and compared with commercial high performance superplasticizers to evaluate their properties. The results showed that HEPC complex and AEPC (1900) compound exhibit an excellent cement adaptability, compared with the commercial WF020and WF023,. Therefore, the HEPC compound reducer and APEG (1900) complex superplasticizer should have a good application prospect.