新拌水泥基材料触变性测试与评价方法研究

Study on Thixotropy Test and Evaluation Method of Fresh Cement⁃based Material

针对新拌水泥基材料触变性难以定量评价的问题,通过系列试验提出从水泥净浆、砂浆、混凝土三个层次递进式评价其触变性的方法。对于新拌净浆,采用触变系数表征其触变性,触变系数越大新拌净浆触变性越好。对于新拌砂浆,采用砂浆形状稳定系数表征其静态触变性,该系数越接近1新拌砂浆静态触变性越好,采用跳桌振动后的最终扩展度与初始扩展度之差表征其动态触变性,差值越大新拌砂浆动态触变性越好。对于新拌混凝土,采用静动态屈服应力比、形态保持系数等指标表征其触变性,静动态屈服应力比和形态保持系数越大新拌混凝土触变性越好。与传统方法相比,该测试和评价方法更具有针对性,简单实用,测试结果直观可靠。

Aiming at the problem that it is difficult to quantitatively evaluate the thixotropy of fresh cement-based material,a progressive evaluation method from three levels of cement paste,mortar and concrete was proposed through a series of tests.For fresh paste,thixotropy coefficient is used to characterize its thixotropy.The greater the thixotropy coefficient,the better the thixotropy of fresh paste.For fresh mortar,the shape stability coefficient of mortar is used to characterize its static thixotropy.The closer the coefficient is to 1,the better the static thixotropy of fresh mortar is.The difference between the final expansion degree and the initial expansion degree after table jumping vibration is used to characterize its dynamic thixotropy.The greater the difference is,the better the dynamic thixotropy of fresh mortar is.For fresh concrete,the thixotropy of fresh concrete is characterized by static and dynamic yield stress ratio and shape retention coefficient.The greater the static and dynamic yield stress ratio and shape retention coefficient,the better the thixotropy of fresh concrete.Compared with traditional methods,the test and evaluation method are more targeted,simple and practical,and the test results are intuitive and reliable.