Synthesis And Applied Research Of The Ether Polycarboxylate Acid Water Reducing Agent

When it is compared with the traditional water reducer， polycarboxylates highperformance superplasticizer has became a research hotspot in the concrete water reducingagent in the21st century because of its advantages，such as low dosage，high water reducingratio，low slump loss，excellent dispersion property，well-designed molecular structure andenvironment protection，and so on. Nowadays，the polycarboxylate is mainly devided into twoparts：the ester polycarboxylate and the ether polycarboxylate. The ether polycarboxylate hassimple polymerization process，short production cycle and low cost，etc，which is comparedwith ester polycarboxylate. According to the principle of molecular structure design，the etherpolycarboxylate with a comb-like molecular structure is synthesized， which containscarboxyl，hydroxy，sulfonic group，polyoxyethylene group and so on.In this paper，modified polyether macromonomer，maleic anhydride，sodium methylallylsulfonate and hydroxypropyl acrylate is used as the main raw material. Under the initiator ofammonium persulphate，the ether polycarboxylate is synthesized by the water solution freeradical polymerization. The paper study the polymerization condition through the cementpaste fluidity experiment，the best ratio of the monomers is： m（MA）：m（SMAS）：m（HPA）：m（TPEG）=3：2：2：1，the dosage of initiator is1.5%ofthe monomer total weight，Polymerization temperature is80℃，the reaction time is4h.Under the optimum synthetic conditions，a series cement paste and mortar experiment isdid by the synthesized polycarboxylate. The experimental results show that，when the dosageof polycarboxylate is0.5%and the water cement ratio is0.35，the cement initial paste fluidityis above240mm，and the paste water-reducing ratio is more than30%，the compressivestrength of cement mortar is40%of28d，and it has a better retarding effect.The structure of synthesized polycarboxylate superplasticizer is characterized by theFTIR and NMR. In order to study the mechanism of the polycarboxylate，the paper measuresthe surface tension of polycarboxylic acid water-reducing agent and Zeta potential on thesurface of the cement particles. The text uses the XRD and SEM to analysis themicro-structure of cement paste，and to study the the influence of the cement hydrationprocess with polycarboxylate superplasticizer.