Synthesis of Modified Polycarboxylate Superplasticizer and Effect on Properties of Cement

In this work, polyether, acrylic acid and oleic acid were used as raw materials to synthesize oleic acid modified polycarboxylate superplasticizer (OA-PCE) by emulsion polymerization, and the synthesis process was optimized by orthogonal experiment. The colloidal interfacial chemistry results concluded that OA-PCE was more capable of reducing the surface tension of aqueous solutions than unmodified traditional polycarboxylate superplasticizer (JS-PCE), and the adsorption capacity on cement particles was more significant. The isothermal adsorption behavior of two kinds of polycarboxylate superplasticizers on cement conformed to the Freundlich isothermal adsorption equation, and it was a physical adsorption process by electrostatic action. The effect of the OA-PCE dosage on the flowability of cement slurry was preliminarily investigated by rheological behavior testing, according to the yield stress, plastic viscosity and thixotropic ring area of slurry, which showed that 0.35 wt% addition of OA-PCE in cement had the optimum effect. The mechanical properties results showed that the compressive strength values of concrete with OA-PCE (0.35 wt%) at 4 h and 7 d were 117.1% and 88.3% higher than those of control group, respectively, which all met the standards for the use of concrete in metro pipe sheets. Therefore, OA-PCE synthesized by emulsion polymerization had certain significance for the development of polycarboxylate superplasticizer both in terms of polymerization methods and practical applications.