Xiao Liu;Ziming Wang;Xu Liang;Jie Zhu;Huiqun Li;Heng Zhou;
<正>In order to achieve rapid transportation and convenient preparation,the polycarboxylate superplasticizer(PCE) was synthesized in non-aqueous system with bulk polymerization.The results showed that the dispersing properties of synthesized PCEs using AIBN as initiator were superior to BPO as initiator under the same conditions.PCE using isopentenyl polyethylene glycol(TPEG) or isobutenyl polyethylene glycol(IPEG) as macromonomer exhibited excellent fluidities and retaining properties at 80OC and 750C,respectively.For AA(acrylic acid) + TPEG + AIBN,the fumaric acid was suitable to copolymerize as the third monomer but the maleic anhydride not.The test results of Fourier Transform infrared spectroscopy(FTIR) confirmed the bulk polymerization for all the monomers.The measurement of molecular weight and distribution showed that the characteristics of molecular weight and distribution for all the synthesized samples were in accordance with their fluidity properties in cement pastes.The synthesized PCE as solid form was dissolved into the water to prepare the PCE solution,and its cement application performances were studied systematically.The results showed that the setting time changed little or shortened slightly after adding PCE.Besides,PCEs with good paste fluidity retentions exhibited the longest final setting time and the shortest setting time interval.The hydration heat curves showed that the PCEs with good fluidity properties can obviously delay the hydration process and lower the hydration heat. Originality Generally the PCE products used in concrete projects are in the form of solution to be provided,and the typical concentration is in the range of 20-50%,which means that more than half of the PCE product is water.A large amount of water in PCE product leads to increased inconvenience such as transportation cost,storage volume and concentration change.The synthesis of PCE powder without any solvent,which likes to the form of dry-mixed mortar,is beneficial to achieving the rapid development of concrete admixture technology. In the theory of polymer chemistry,the polymerization product can be obtained by bulk polymerization u~(211)nder a non-aqueous condition.Therefore,this polymerization method is applied to the synthesis of PCE in this investigation.There are at least two advantages for this innovation:the one is that the synthesized product is directly solid state,which can be pulverized into the form of powder to be convenient to load,unload,and save space;the other one is that the arbitrary concentration of PCE can be prepared by the final polymerization product whether in laboratory or in construction site.Such superiorities can widen the application of solid PCE in construction engineering.
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