水泥浆体屈服应力和黏度与其测试分析影响因素研究

采用RHEOLAB QC型旋转黏度计,分别以转速与剪切速率为控制变量测定了水泥浆体稳态流变曲线,分别用Couette转换与流变模型研究了水泥浆体屈服应力和黏度与测试及分析影响因素之间的关系.结果表明:Couette转换能反映测试条件变化对屈服应力和黏度的影响;增大试样筒与转子的间距,由转速转化的剪切速率增大,颗粒迁移作用增强,动态屈服应力递减,塑性黏度递增;增大试样筒外壁的摩擦系数,浆体与外筒壁间相对运动情况不发生变化,对动态屈服应力与塑性黏度基本无影响;依据拟合相关系数,流变模型中Herschel-Bulkley模型的吻合程度最好;依据结果标准差,Herschel-Bulkley模型的动态屈服应力结果稳定性最好,Bingham与改进Bingham模型的塑性黏度结果的稳定性相差不大.

Effect Factors of Measurement and Analysis on Yield Stress and Viscosity of Cement Paste

The steady state rheological curves of cement paste were determined with control variables of shear rate and rotate speed by means of RHEOLAB QC rotary viscometer, and the effects of testing and rheological methods on the yield stress and viscosity of cement paste were studied through Couette inverse and rheological models.The results show that:results derived from Couette inverse reflect a better effect of testing methods on the measurement, when the gap between van and cup increases, the shear rate derived from rotate speed and particle migration of cement paste increase, and the plastic viscosity increases,while the dynamic yield stress gradually decreases; the friction coefficients of the external cylinder do not change the relative motion between the paste and outer cylinder and have little influence on the dynamic yield stress.Based on the fitting coefficients, Herschel-Bulkley model fits best with the registered data.Based on the standard deviation values,Herschel-Bulkley model has the best stability of dynamic yield stress,and stability of Bingham model is basically the same as modified Bingham model.