砂浆静-动态流变的黏弹塑性特征

Viscoelasticity characteristics of mortars in static and dynamic rheological test

基于静态与动态流变学理论,利用共轴圆筒式流变仪,研究了高性能砂浆的黏弹塑性行为。在低水胶比条件下,通过调整减水剂掺量,使各组砂浆具有相同的初始坍落扩展度,静态流变测试结果表明粉煤灰微珠或石灰石粉掺入均可降低砂浆屈服应力、塑性黏度、触变性及其经时变化率,而动态流变测试结果则反映了粉煤灰微珠和石灰石粉加入后,砂浆局部网络结构密集程度提高及絮凝结构流态改变所需耗散能量减少的情况。试验证明,砂浆的静态表观黏度与动态复数黏度、静态滞回环面积与动态损耗模量-转速曲线所包围的面积随水化时间的变化规律是一致的,采用静/动态流变行为同时测定的方法可以综合描述砂浆的黏弹塑性。

Based on the theory of static and dynamic rheology, the viscoelasticity of high performance mor-tar is studied using a coaxial cylinder rheometer. With a low water-to-binder ratio, the slump flow of mor-tars is about the same by adjusting the dosage of superplasticizer. The static rheological test results of freshmortars indicate that the addition of fly ash microsphere（FAM） or limestone powder（LP） can reduce theyield stress, plastic viscosity and thixotropy, as well as their growth rate over time. The dynamic rheologi-cal test results reflect the higher intensities of partial physical crosslinking network and the reduction of en-ergy consumption in changing of flocculent structure flowability in mortars when FAM or LP has been add-ed. It has been proved that the static apparent viscosity and dynamic complex viscosity, the area of statichysteresis loop and the area surrounded by dynamic loss modulus-speed curves both show a strong consis-tency along with hydration time. Measuring static and dynamic rheological behavior simultaneously can com-prehensively describe the viscoelasticity of mortars.