Preparation Of High Performance Polycarboxylate Superplasticizers And Their Adaptability To Clay

As the third generation high-performance water reducer,polycarboxylate superplasticizers(PCE)have the advantages of low dosage,high water reduction rate,flexible molecular structures,and environmental friendliness.However,among which the polycarboxylate superplasticizers exhibit outstanding sensitivity to clay in practical application.From the point view of molecular structure design,the functional monomer of[2-(Methacryloyloxy)ethyl]trimethylammonium chloride solution(DMC),3-dimethyl(methacryloyloxyethyl)ammonium propane sulfonate(DMAPS)and acrylamide(AM)with cationic groups were introduced into the structure of traditional polycarboxylate superplasticizers.The effects of acid-ether ratio,the dosage of functional monomer and initiator on the dispersion of polycarboxylate superplasticizers were discussed,and the optimum synthetic ratio was obtained.And these reaction conditions,three kinds of polycarboxylate superplasticizers with high performance(APC1,APC2 and APC3)were synthesized respectively.The relative molecular weights and the molecular weight distributions of polycarboxylate superplasticizers were analyzed by GPC.The results showed that the molecular weight of the polycarboxylate superplasticizers ranged from25000 to 40000 g/mol,and the polydispersity indexes(PDI)were fine.The molecular structure of polycarboxylate superplasticizers with high performance was characterized by ~1H NMR and FT-IR,and the results indicated that the three polycarboxylate superplasticizers had been successfully prepared.The performance test of the self-made high performance polycarboxylate superplasticizers shows that the high performance polycarboxylate superplasticizers has better dispersibility,dispersion retention and water reducing performance than the traditional polycarboxylate superplasticizers.The strength of the samples with the addition of three high-performance polycarboxylate superplasticizers is slightly higher than that of the samples combined with PCE1 and PCE2,and the comprehensive performance of APC1 was the best among them.The fluidity of cement paste mixed with sodium bentonite showed that the as-prepared high performance polycarboxylate superplasticizers have good dispersibility and dispersion retention,and the comprehensive performance of APC1was the best among them.The TOC results indicated that the as-prepared polycarboxylate superplasticizers with high-performance has selective adsorption on cement and clay particles and good adaptability to clay.And the XRD and TGA results indicated that the polycarboxylate superplasticizers adsorbed with sodium bentonite.?-Cyclodextrin(?-CD)-based zwitterionic clay inhibitors were synthesized via activators regenerated by electron transfer for atom transfer radical polymerization(ATRP)and monomer DMAPS polymerization initiated by macroinitiator based on?-CD.When the content of clay inhibitor was 0.195‰in pure cement paste and 1%bentonite cement paste,it has good fluidity,flow retention and mud resistance.