浆液的流变类型是研究注浆扩散模型的基础,采用旋转黏度计对不同水灰比、温度及水化时间条件下的普通硅酸盐水泥浆液的流变特性进行测试。结果表明:(1)在20℃-50℃范围内,不同水灰比的水泥浆液,同级剪切速率下温度对剪切力的影响有所不同。水灰比为0.5,0.7的浆液在同级剪切速率下,剪切力随温度增加而增大,且比较显著;而对水灰比1.0,1.5,2.0的浆液,在同级剪切速率下,剪切力均随着温度增加而减小,温度对水灰比为1.0的浆液的剪切力的影响最小。(2)搅拌状态下浆液在同级剪切速率下的剪切力均随着水化时间的增加而增加,且温度越高,剪切力增加的幅度越大。(3)在20℃-50℃范围内,各特定水灰比浆液的流变模式并未随温度、水化时间发生显著的改变。(4)水灰比对水泥浆液的流型起主导控制作用。水灰比为0.5,0.7的浆液表现出具有屈服应力的幂律流体模式,其屈服应力、稠度系数随着温度、水化时间增加而增长,而流变指数随温度、水化时间的增加而减小;对水灰比为0.7的浆液,其剪切力–剪切速率的非线性关系并不显著,可将其简化采用宾汉流变模式近似描述,其拟合结果与测试数据点仍具有较高的相关性,水灰比为1.0的浆液为具有屈服应力的宾汉流体,但是屈服应力较小,可以近似为牛顿流体,采用牛顿流变方程描述其流变特性;水灰比1.5,2.0的水泥浆液则表现出牛顿流体特征;水灰比1.0,1.5,2.0的水泥浆液,其动力黏度随着温度的增加逐渐减小,但随着水化时间的增加而增大。
Grout rheological type is the foundation of grouting diffusion model research. Under different conditions of water cement ratio(W/C),temperature,hydration time and the rheological properties of ordinary portland cement grout were investigated by rotary viscometer. The results show that:(1) When temperature is 20 ℃–50 ℃,the effect laws of temperature on the shear force under the same shear rate change with W/C. The shear force increases with the rise of temperature when W/C of 0.5 and 0.7. However,the shear force decreases with the rise of temperature when W/C of 1.0,1.5 and 2.0.(2) The shear force under stirred up condition increases with the increasing of hydration time at the same shear rate,and the higher of the temperature,the bigger of the increment of shear force.(3) The rheological pattern of cement grout does not change too much under the different temperatures and hydration times when the temperature is 20 ℃–50 ℃.(4) The flow pattern of cement grout is controlled by W/C. The cement grouts with W/C of 0.5 and 0.7 are power-law fluid with yield stress. With the increase of temperature and hydration time,the yield stress and consistency factor shows increasing trend. While the flow behavior index decreases with the increase of temperature and hydration time. When W/C is 0.7,the non-linear relationship between shear force and shear rate is not so significant. So the rheological behavior can be simplified to Bingham rheological model,which fits the test data point very well. When W/C is 1.0,the rheological behavior of cement grout displays Bingham fluid with unapparent yield stress,which can be considered as a Newtonian fluid and use Newtonian rheological equation to describe its rheological behavior. When W/C is 1.5 and 2.0,the cement grouts are Newtonian fluid. When W/C is 1.0,1.5 and 2.0,the dynamic viscosity of cement grout decreases with the increasing of temperature,while it increases with the increasing of hydration time.