The Study On Synthesis Process And Properties Of Novel Polycarboxlate Based Plasticizer

Polycarboxylate based plasticizer is an ideal product of high range water reducer because of its small dosage,excellent ability of water reducing,low slump loss,simple production process and green environmental protection in the course of using.In developed countries,it has become the major varieties of concrete water reducer,while in domestic,it has mainly used for key projects and being increasingly used for civil commercial concrete projects currently.In engineering practice,the performance price ratio of polycarboxylate based plasticizer is not high enough,and the raw materials mainly depended on ethylene.In order to obtain polycarboxylate based plasticizer of higher performance price ratio,in this paper,a new structure has been designed.Maleic acid monoesters and N-glycinymaleamic acid of combined with allyl polyether and acrylic acid were used to synthesize a polycarboxylate based plasticizer.On the basis of orthogonal experiment,optimum molar ratio of raw materials was determined,that was,n(GMA):n(AA):n(MM):n(APEG1300)=0.8:1.8:0.7:1.1.Furthermore,optimum synthesis process was determined by single factor analysis and synthesis process optimization,that was,the initiator dosage of 3wt%,the reaction temperature of 80℃ and the reaction time of 3.5h.On the basis of optimum synthesis process,the effect of maleic anhydride instead of maleic acid monoesters on the properties of Polycarboxylate based plasticizer was studied.Maleic acid monoesters combined with MA according to a certain proportion were used to synthesize polycarboxylate based plasticizer PC-A1、PC-X1,the addition of which was 0.2wt%in the Portland Clinker of P.042.5,the initial fluidity of cement paste reached as high as 286 mm,288 mm respectively,and fluidity were 297 mm,299 mm after 2 hours.The effect of small molecule salt,GMA and PC-X1 on properties of cement and the cooperativity were studied.The results showed that the cooperativity of sodium tetraborate and PC-X1 performed well.When the addition was 0.6g,the initial fluidity of cement paste reached as high as 295mm,and the fluidity was 265mm after 2 hours,which was increased by 10mm,40mm respectively compared to the blank experiment.GMA which was added to PC-X1 had a significant impact on the solidification time of cement.When the addition of GMA was 0.6g,the solidification time reduced to 8h.Finally,the stability of synthesis process was studied.The results showed that synthesis process of PC-X1 had good stability.Furthermore,the application of PC-X1 in C30 concrete was also studied,when the addition was 0.18wt%,C30 concrete had better compressive mechanical property.Compared to marketed water-reducer PC-1,the compressive strength of concrete reached to 33.65MPa after 28 days.