纳米SiO2对水泥剪切强度及浆液流变性质影响的试验研究

Experimental Study on Effect of Nano-SiO on Shear Strength and Rheological Properties of Cement

为了研究纳米SiO2对水泥剪切强度及流变性质的影响,针对水灰比1.0和3 d养护时间下的不同水泥试样开展了一系列不同法向应力条件下的直剪试验,研究了纳米SiO2颗粒对试样的剪切行为及剪切强度参数(剪切强度、黏聚力、内摩擦角)影响规律,以及减水剂对浆液流变性质的影响规律。结果表明:水泥结石体试样随着剪切位移的增大,剪切应力逐渐增大,直至达到峰值应力,之后表现为应变软化阶段;添加纳米SiO2后,结石体试件的黏聚力和内摩擦角分别提高了8.2%和4.1%。添加纳米SiO2的浆液黏度明显增加;通过添加1.5%含量的减水剂,可以显著提高含纳米SiO2浆液的流动性,从而获得具有高流动性和渗透能力的浆液。

In order to study the effect of nano-SiO2 on shear strength and rheological properties of cement grout, a series of direct shear tests were conducted under multiple constant normal loads for cement grouted samples with water-cement ratio of 1.0 and 3-day curing time. Then, the influence of nano-SiO2 on shear behavior and shear strength parameters (τp, c and φ) of samples was studied, and the rheological properties of grouts after adding super plasticizer were further studied. The results showed that with the increase of shear displacement, the shear stress increased gradually until the peak stress was reached, and then it appeared as strain softening stage. After the addition of nano-SiO2, the cohesion and internal friction angle of the samples were increased by 8.2 % and 4.1 %, respectively. The viscosity of grouts containing nano-SiO2 increased significantly. By adding 1.5 %super plasticizer, the fluidity of the grouts containing nano-SiO2 could be significantly improved, so as to obtain the grouts with high fluidity and permeability.