剪切速率和温度对低水胶比水泥浆流变性能的影响

Effects of Shear Rate and Temperature on Rheology of Cement Paste with Low Water-to-Binder Ratio

水泥浆体的流变性能不仅与材料本身有关,还受环境及外部作用影响。本文针对水泥基材料实际工程中存在的主要外部影响因素,即剪切作用与环境温度,研究了两者对低水胶比水泥浆流变性能的耦合作用。结果表明:水泥浆体在剪切过程中的流变行为与所施加的预剪切有关,水泥浆体的屈服应力随预剪切速率的增大而减小,剪切增稠的程度随预剪切速率的增大而增大;温度升高,水泥颗粒对减水剂的吸附量增加,浆体在不同剪切速率下的平衡表观黏度减小;温度和剪切速率对水泥浆平衡表观黏度的影响具有耦合效应,剪切速率越高,温度的影响越小,反之亦然,并建立了不同温度和剪切速率下平衡表观黏度的数学关系。

The rheological properties of cement paste are not only related to its proportion,but also influenced by the environmental effects.In this paper,considering the main external effect factors existed in the actual engineering of cement-based materials,the influences of temperature and shear rate on the rheology of cement paste with low water-to-binder ratio were investigated.The results show that the rheological properties of cement paste are related to the pre-shearing before data logging,the yield stress decreases and shear-thickening intensity increases with the increasing pre-shearing rate.The superplasticizer adsorption on cement particles increases and the apparent viscosity at equilibrium decreases with the elevating temperature.Besides,the effects of temperature and shear rate on the equilibrium apparent viscosity of cement paste have a coupling effect.The higher the shear rate,the smaller the effect of temperature,and vice versa.The mathematical relationship of equilibrium apparent viscosity under different temperatures and shear rates is established.