Synthesis And Characterization Of Functional Polycarboxylate Superplasticizer

Water reducing admixture and rust inhibitors are widely used cement concrete additives in the construction. Polycarboxylate series of high performance water reducer developes fasterly in recent years. Polycarboxylate superplasticizer can effectively improve the strength and performance of concrete, save cement dosage and energy consumption. Amino acid is one of the most promising green rebar inhibitor, which is biodegradable, environmental-friendly, low cost, widely variety and sources.The carboxy of arginine(Arg) was freed out via p-toluene sulfonic acid method. A monoester(AP) grafted with arginine p-toluene sulfonate was synthesized by esterification reaction of excessive polyethylene glycol(PEG) and arginine p-toluene sulfonate(AT). AP(I,Ⅱ,Ⅲ) was synthesized by PEG(400, 1000, 1500) and AT. APM(I,Ⅱ,Ⅲ) was synthesized by AP(I,Ⅱ,Ⅲ) and methacrylic acid(MAA). APC(I,Ⅱ,Ⅲ) was synthesized by APM(I,Ⅱ,Ⅲ) as macromonoester via polymerization. The test results showed that the APC(II) was more suitable in industrial production for the prominent performance of cement concrete and rust corrosion inhibition. Synthesis of APC(Ⅱ) was divided into three stages: AP(Ⅱ) was synthesized with esterification rate of 95% by PEG1000 and AT in molar ratio of 1.3:1 by p-toluenesulfonic acid(2wt% of PEG1000 and AT)-catalyzed for 9h at 115℃. APM(Ⅱ) was synthesized with esterification rate of 97% by AP(Ⅱ) and MAA in molar ratio of 1.3:1 by p-toluenesulfonic acid(2wt% of AP(Ⅱ) and MAA)-catalyzed and hydroquinone(1wt% of MAA) as polymerization inhibitor for 7h at 110℃. APC(Ⅱ) was synthesized by ammonium persulfate(10wt% of all monomers)- initiated radical copolymerization reaction of macromonomer APM(Ⅱ), MAA and methyl allyl sulfonate(SMAS) in molar ratio of 1.0: 4.0:1.25 at 90 for 1℃.5h. The test results showed that the fluidity of cement paste, the water reduction and the compressive strength of APC(Ⅱ) was 317 mm, 30%, and 50.6MPa, respectively.As the control test of APC, polycarboxylate superplasticizer(PC) was synthesized by homemade macromonomer(PM). The synthesis process and parameters of PC according to APC. PM(Ⅱ) was synthesized with esterification rate of 97% by PEG1000 and MAA in molar ratio of 1:3.0 by p-toluenesulfonic acid(2 wt% of PEG1000 and MAA)-catalyzed and hydroquinone(1wt% of MAA) as polymerization inhibitor for 3.5h at 95℃. PC(Ⅱ) was synthesized by ammonium persulfate(10wt% of all monomers)- initiated radical copolymerization reaction of PM(Ⅱ), MAA and methyl allyl sulfonate(SMAS) in molar ratio of 1:4.0:1.25 for 3.5h at 95℃. The test results showed that the fluidity of cement paste, the water reduction and the compressive strength of PC( Ⅱ) was 330 mm, 32%, and 51.2MPa, respectively.The performance of APC were roughly similar with PC. APC(II) and PC(II) were prominent in fluidity of cement paste, water reduction and compressive strength, which met the required national standards of GB 8076-2008 about high performance water reducing agent. The structures of monoester, macromonomer, PC and APC were characterized by FTIR. For the coordination effect of metal and Arg containing more amine groups, the adsorption of water reducer in steel surface was enhanced, which reduced the contact between harmful substances and reinforced effectively. The test in rust corrosion resistance showed that APC(II) could restrain the cathode and anode reaction at the same time, and mainly for anode corrosion inhibition, which did work in the aspect of reinforcing steel bar rust than PC(II).