石灰石粉对水泥浆体流变性能的影响及作用机理

研究了相同流动度下石灰石粉对水泥浆体流变性能的影响规律,并采用Zeta电位仪和偏光显微镜测试了浆体Zeta电位及显微结构,通过最小需水量法分析了水泥浆体中颗粒湿堆积密实度和颗粒表面的水膜层厚度,探讨了石灰石粉对水泥浆体流变性能的作用机理.结果表明:流动度相同时,浆体的屈服应力基本相同;随着石灰石粉细度的减小以及掺量的增加,水泥浆体的黏度逐渐降低;石灰石粉在水溶液中的Zeta电位显著高于水泥,因此可大幅度减少水泥浆体中的絮凝结构,增大水泥浆体中颗粒湿堆积密实度,从而释放出更多自由水,增加颗粒表面的水膜层厚度,进而降低颗粒间相互作用力,导致水泥浆体黏度显著降低.

Effect of Limestone Powder on Rheological Properties of Cement Paste and Its Mechanism

The effect of limestone powder on rheological properties of cement paste with the same fluidity was investigated. In order to study its mechanism, Zeta potentiometer and optical microscope were employed to test the Zeta potential and microstructure of paste, respectively. Also the minimum water demand method was used to analyze wet packing density of particles in paste and water film thickness on the surface of particles. The results show that for paste with the same fluidity, yield stress is almost the same, but viscosity decreases gradually with the decrease of limestone powder fineness and increase content of limestone powder. The Zeta potential of limestone powder in aqueous solution is significantly higher than that of cement, which can significantly reduce the flocculation structure in cement paste and increase the packing density. The increased packing density indicates that more free water is released, thereby the thickness of the water film on the surface of the particles is increased and further the interaction force between particles is reduced, which leads to a significant reduction in viscosity of cement paste.