The Research Of Viscosity-Modifying Admixture Of Concrete

Viscosity-modifying admixture(VMA) is more and more used in cement and concrete, which mainly serve as an important admixture component of self-leveling concrete, self-compacting concrete and shotcrete. It has good effect for viscosity-modifying admixture to reduce water dilution, bleeding, segregation and sedimentation in cement-based systems.The research is a systemic study on VMA including itself properties and the adaptability between VAM and different High-range water-reducers(HRWR). In the course of it, rheological characteristics of cement paste and motar are researched by rheology theory. What is more, workable and thixotropic exponent are indexed to depict rheological property of paste and good effect is achieved. Results of experiments are as follow. HRWRs exist saturated concentration when addition of VAM is fixed; Fluidity of the cement paste is in inverse proportion to the saturated concentration of HRWRs under the condition of invariable concentration of VAM and uniform concentration of HRWR; Rheological characteristic of the cement pastes follows Bingham model; adaptability between ZH and HPMC, SM and PAM,ZH and HEC and between FDN and CMC is gopd.At the same time, the results of the concrete containing VAM experiments show VAM can effectively improve the fluidity of the concrete, reduce bleeding, segregation and sedimentation of the cement concrete.