Research On Control-released Polycarboxylic Superpiasticizer

In recent years, the third generation of superplasticizer—the polycarboxylic highperformance superplasticizer is more and more widely used. The advantages bring greatconvenience to the concrete quality control. But these also bring the problem that causeconcrete slump loss. a lot of difficulties of the concrete quality control come out with thevarious of the concrete materials. The ordinary polycarboxylic superplasticizer can hardly makeconcrete admixture to keep good workability and slump retention at present. But controlledreleased polycarboxylic superplasticizer can effectively reduce the concrete slump loss, keepconcrete has good performance in a long time, at the same time it has good mechanicalperformance and durability.This paper research on the synthesize of controlled released polycarboxylicsuperplasticizer and use the single factor experiment method to determine the optimumsynthesis process and the best reaction ratio of materials. Using the methyl allylpolyoxyethylene ether (TPEG) and acrylic acid (AA) as the main material under the action ofcomposite initiator to synthesize controlled released polycarboxyllic superplasticizer. Theoptimum reaction synthesis process is n(AA)：n(SAS)：n(seignette salt)：n(TPEG)=3.25:0.27:0.04:1, the composite initiator is0.25%of TPEG, the reaction temperature is70℃, the reactiontime is4h. The cement paste fluidity can reach300mm when mixing with the superplastidizerin this condition and the fluidity is280mm after1h.The contrast test is carried out by selecting5different kind of cement in order to do somefurther researches of the controlled released polycarboxylic superplasticizer. Both sample U30and sample U35show optimum adaptability to all these cement. The cement paste fluidity anddispersion stability are preferable. Its performance is better than SP010-GC and TJB-01.according to the concrete test, U35shows optimum controlled-release result, U30is worse thanthe U35, the SP010-GC and TJB-01are the worst. Through mechanical test, the mechanicalproperties of all these superplasticizer are similar.Through the infrared spectrogram, the molecular structures of the U30and U35are quitesimilar to the SP010-GC and TJB-01. hydroxyl vibration absorption peak of the four samplesare almost the same, it shows that the four superplasticizers have the function of delayedcoagulation. The monomer conversion rate of U35is the highest because the C-H absorptionpeak of U35is the strongest. According to the highest—COOH absorption peak, the U35hasthe optimum ability of slump retaining. The C-O-C absorption peak of the U35reaches the topshows that its side chain density is the highest. All superplasticizer have the fuction group of—COOH,—SO32-and—OH. These show that the synthesized superplasticizer has the functionof controlled release in the molecular structure.