Experimental Study On Polycarboxylate-based Superplasiticizers

Polycarboxylate-based Superplasiticizers have the characteristics of lower dosage, high water-reducing ratio and low slump loss of concrete mixture, which have become an important research item in high performance water-reducing agents of concrete.In this paper, by using polyoxyethylene(PEG) and acrylic acid(AA) as main raw materials, a type of medium esterified macromonomer(PA) was prepared. The condition of esterification action of PA was explored, i.e. the influences of solvents, temperature, time and catalyst etc. on esterification rate were investigated. Then, a type of comb-type polycarboxylate-based superplasticizer was synthesized by using acrylic acid, PA made by ourselves and sodium allylsulfonate(SAS). The conditions of synthesis such as temperature, reaction time, pH value, the types and dosage of chain transfer agents and initiators etc. were studied. A product of polycarboxylate-based superplasticizers was prepared under best condition. The compounding performances of the product made by ourselves with different retarders were researched. The obtained results indicate that the best cooperating effect can be achieved when the product compounded with sodium gluconate. The experiments of performance inspecting of cement paste and concrete added with the compounded product were conducted. The results show that the compounded product has better compatibility with cement; based on standard GB8076-1997, concrete experiment indicate the compounded product having water-reducing ratio of 31.9% under the dosage of 0.3% solid weight, and the compressive strength ratios at 3d, 7d, 28d of 169.4% ,185.9% and 155 % respectively.