Study On Synthesis And Performance Of Polycarboxylic Type Superplasticizer

This paper focuses on a series of problems of polycarboxylic typesuperplasticizer,based on the principle of molecular design and the research of radical polymerization andoptimization matching monomer activity, a polycarboxylic type superplasticizer wassynthesized withsimplely process, low energy consumption, less side effects, lowaccretion and high water-reducing rate, and the function mechanism has been discussedby the research of the relationship between structure and adsorption, adsorptionanddispersion.(1) A polycarboxylic type superplasticizer was synthesized with OXAB, MAS andMAL.The best reactant ratio were n(OXAB):n(MAL):n(MAS)=0.85:2.75:0.3andm(APS)=3.5%, and the optimalreaction conditions were80℃for2.5h and then90℃for0.5h, which was obtainedvia orthogonal test and single factor optimize. The initial slumpof C40concrete containing the0.8%superplasticizerwas235mm and remained85mmafter1h.Air content of the concrete was3.8%,and its strength reached up to62.7MPaat28d.(2) Isopropanol has been replaced by methyl-2-propen-1-olto synthesize OXAC,which is more facile and more cheaper. A polycarboxylic type superplasticizer wassynthesized with OXAC and AA.The best reactant ratio were n(OXAC):n(AA)=0.046:0.175and m(H2O2)=1.2%, m(VC)=26.9%, and the optimalreaction conditionswere60℃for5.0h, which was obtainedvia orthogonal test and single factor optimize.The initial slump of C40concrete containing the0.92%superplasticizerwas217mm andremained195mm after1h.Air content of the concrete was3.5%,and its strength reachedup to65.4MPaat28d.(3) Effect of hydration time and hydration temperature on the amount of PC that adsorbed onthe surface of cement particles have been studied.The adsorbance maximizing in20minutes. Thehigher the hydration temperature, the higher the adsorbance. (4) Adsorption isotherm of PC with different serieshas been studied. With the increase ofthe content of anion and the decrease of side chain length, the adsorbance increasegradually. With ester ratio increased, the adsorbance first increases, then decreases, whenthe ester ratio was7:1, it has the best adsorption performance. PC with different side chainhas been fitting with Langmuir model and Freundlich model. The result shows that Langmuirmodel is more suitable, correlationindex are more than0.97.Saturatedadsorbance and thetrend of equilibriumconstantare consistent with the experimental result. Freundlichmodel is inappropriated, the correlation index are less than0.90.