基于稳态流变测试的水泥浆体剪切模式研究

采用RHEORIAB QC型旋转黏度计测定不同剪切方式下水泥浆体稳态流变曲线,并用修正宾汉姆流变模型对其进行拟合,研究了剪切方式对水泥浆体稳态流变测试的影响.结果表明:预剪切对水泥浆体动态屈服应力和塑性黏度影响不大.恒定剪切变形速率小于、等于、大于、偏大于水泥浆体结构抗剪切破坏能力时,剪切应力随时间分别先线性增加接着保持同一值、直接保持恒定值、先减小接着保持同一值、轻微增加后达到平衡.随剪切速率增加,水泥浆体在0.1～100 s-1、100～400 s-1、400～600 s-1三个区段依次呈现出剪切变稀、宾汉姆流体、剪切增稠的流变行为.剪切速率变化范围向剪切变稀或剪切增稠段移动,水泥浆体动态屈服应力减小、塑性黏度增大;单个剪切速率的剪切时间越长,水泥浆体动态屈服应力、塑性黏度均越小.

Shear Protocols of Cement Paste Based on Steady-State Rheological Test

The steady-state rheological curves of cement paste under different shear protocols were determined by means of RHEORIAB QC rotary viscometer,and the effect of shear protocols on steady-state rheology of cement paste was studied by fitting curves to the modified Bingham rheological model.The results show that: Pre-shearing has little effect on the dynamic yield stress and plastic viscosity of cement paste,when the constant shear rate of the cement paste is less than,equal to,greater than or much greater than the shear resistance of initial structure,the shear stress show trends of keeping the same value after a linear increase,keeping a constant value,decreasing and then keeping constant or increasing slightly and then reaching an equilibrium with time.With the increase of shear rate,the cement pastes show rheological behaviors in turn of shear thinning,Bingham fluid and shear thickening in the intervals of 0.1-100 s-1,100-400 s-1,400-600 s-1 respectively.The range of the shear rate shifts to the shear thinning or shear thickening rate interval,the dynamic yield stress of the cement paste decreases and the plastic viscosity increases.The longer the shear time of a single shear rate is,the smaller the dynamic yield stress and plastic viscosity of the cement paste are.