The Synthesis And Performance Of Low Air Entraining And Set Retarding Polycarboxylate Superplasticizer

The low air entraining and set retarding polycarboxylate superplasticizer has excellentperformance,applicable to many concrete engineering,including mass concrete,the constructionconcrete of hot weather conditions,the concrete of long time parking or long distancetransportation, high strength concrete-high performance concrete,high fluidity concrete,andpumpable concrete,etc.Through the molecular design theory, put the required features functional groups into themolecular structure of polycarboxylate superplasticizer,to get the low air entraining and setretarding polycarboxylate superplasticizer. The main affecting factors of synthetic low airentraining and set retarding polycarboxylate superplasticizer was researched.Further definesynthesis conditions of low air entraining and set retarding polycarboxylate superplasticizer.Theexperiment showed that the dosage of initiator was6.8%to the weight of macromonomer, themass ratio of macromonomer, maleic anhydride, sodium methylallyl sulfonate and acrylamidewas1︰0.235︰0.100︰0.027,the reaction temperature was about80℃,the reaction time was6to7hours,the low air entraining and set retarding polycarboxylate superplasticizer of the betterfluidity of cement paste and better dispersity has synthesized.The relevant characteristic functional group found in the molecule polycarboxylatesuperplasticizer with the FT-IR characterization, these characteristic functional group includedhydroxy groups, sulfonic acid groups,carboxyl groups, acylamino groups, ether groups, etc.Themolecular structure of low air entraining and set retarding polycarboxylate superplasticizer tallywith designing molecular structure.This means that characteristic functional groups had greatinfluence on the performance of the low air entraining and set retarding polycarboxylatesuperplasticize.The performance of low air entraining and set retarding polycarboxylate superplasticizerhas tested. The result showed that the low air entraining and set retarding polycarboxylatesuperplasticize had better dispersity,better maintain plasticity,high water reducing rate, havinggood low air entraining effect, obvious slow condensation effect,and good effect of compressivestrength of concrete in the smaller content; Using different brand cement testing，the low airentraining and set retarding polycarboxylate superplasticize had strong adaptability.The testing of SEM for the low air entraining and set retarding polycarboxylatesuperplasticize,the influence of the low air entraining and set retarding polycarboxylatesuperplasticize on porosity and pore size distribution of cement,dispersion of cement andhydration of cement.In microcosmic view, demonstrated that low air entraining and set retardingpolycarboxylate superplasticize had better performance.The important influence of molecular structure of the low air entraining and set retarding polycarboxylate superplasticize on itsperformance.The compact relation of molecular structure of the low air entraining and setretarding polycarboxylate superplasticize, performance of the low air entraining and set retardingpolycarboxylate superplasticize and micro morphology of cement.The important influence ofmolecular structure of the low air entraining and set retarding polycarboxylate superplasticize onits performance and micro morphology of cement.