Study On Design And Synthesis Of Water-reducing Agent For High Flow And High Maintainability Cement Slurry

Polycarboxylic acid superplasticizer is a kind of surfactant which can adsorb on the surface of cement particles.Its molecular structure is special,the preparation process is simple and controllable,the dispersion effect of cement particles can be improved significantly under the condition of low admixture,and the strength,cold tolerance and compressive resistance of concrete have great influence on construction.Based on the molecular configuration and mechanism of polycarboxylic acid superplasticizer,a new type of polycarboxylic acid superplasticizer was prepared by free radical polymerization TPEG（2400）different small monomers and large monomers.The molecular structure of the product was characterized by infrared spectroscopy.The molecular weight of the product was analyzed by liquid-mass spectrometer.Using acrylic acid as small monomer,TPEG（2400）as large monomer,green nontoxic H₂O₂-Vc as redox system to initiate free radical polymerization reaction to obtain acrylic acid system high efficiency polycarboxylic acid superplasticizer,the best synthesis scheme was determined by optimizing the material ratio.When the molar mass ratio of monomer is 4:1,the addition of oxidant is 2.0%,the addition of reducing agent is 0.48%,and the dosage of adding and reducing water is 0.12%,the slurry fluidity of cement can still reach 260 mm,60min after it reaches 330 mm,and the test effect of different kinds of cement is quite remarkable,among which the maximum fluidity of reference cement slurry can reach 325 mm,and the research results have good practical application prospect.Under the same experimental conditions,NVP water reducing agent was synthesized by polymerization TPEG（2400）small monomer and large monomer with more hydrophilic NVP.When the molar mass ratio of monomer is 3.5:1,the fluidity of cement slurry reaches 290 mm,1h mm;and the polymerization of maleic anhydride with larger monomer with higher carboxyl content is achieved.When the reaction temperature rises to 80°C,the other experimental conditions remain unchanged,the net slurry fluidity of cement can reach 220 mm.