发泡浆体流变特性对轻质混凝土匀质性的影响

为改善轻质混凝土匀质性,提升轻质混凝土力学性能,本文通过建立Herschel-Bulkley(H-B)塑性黏度计算模型,探究了发泡浆体流变特性对泡沫沉降和浆体中陶粒分布的影响。结果表明：随增稠剂掺量的增加,轻质混凝土发泡浆体的屈服应力和基于非线性H-B模型η_H-B=0.016 67K(80ⁿ-20ⁿ)(η_H-B为H-B模型得出的发泡浆体塑性黏度;K为一致性系数;n为流动指数)得到的塑性黏度增大,导致发泡浆体沉降距下降,陶粒在浆体中的分形维数提高;当发泡浆体塑性黏度大于1.74 Pa·s、屈服应力大于92.87 Pa时,可制备抗压强度大于10 MPa的轻质混凝土。由此可见,优化发泡浆体流变特性是克服陶粒在发泡浆体中易上浮问题的关键,可有效改善轻质混凝土匀质性,提升轻质混凝土力学性能。

Effects of Rheological Properties of Foamed Slurry on Homogeneity of Lightweight Concrete

In order to improve the homogeneity of lightweight concrete and enhance the mechanical properties of lightweight concrete, the Herschel-Bulkley (H-B) plastic viscosity calculation model was established to explore the influences of rheological characteristics of foamed slurry on the foam settlement and ceramsite distribution in slurry. The results show that with the increase of thickener content, the yield stress and the plastic viscosity of lightweight concrete foamed slurry based on nonlinear H-B model η_H-B=0.016 67K(80ⁿ-20ⁿ) (η_H-B is the plastic viscosity of foamed slurry obtained by H-B calculation model; K is consistency coefficient; n is flow index) increase. As a result, the settlement distance of foamed slurry decreases and the fractal dimension of ceramsite in slurry increases. When the plastic viscosity of foamed slurry is greater than 1.74 Pa·s and the yield stress is greater than 92.87 Pa, the lightweight concrete with compressive strength greater than 10 MPa is prepared. It is seen that optimizing the rheological properties of the foamed slurry is the key to overcome the easy floating problem of ceramsite in foamed slurry, which can effectively improve the homogeneity of lightweight concrete and enhance the mechanical properties of lightweight concrete.