Prediction of the rheological properties of mortar compounded with desert sand and Pisha sandstone ceramic sand based on density-form coupling.

Ordos, China has a large amount of environmentally hazardous Pisha sandstone and desert sand. Pisha sandstone ceramic sand and desert sand can be compounded to prepare light and fine aggregates, which are often used in construction mortar. However, it is unknown how the density and particle shapes of light and fine aggregates affect their rheological properties. In this study, we establish a predictive model for the rheological properties of light and fine aggregate mortar, using the Krieger-Dougherty and Chateau-Ovarlez-Trung models as a basis. First, density and particle morphology parameters are introduced and modified for light and fine aggregate mortars. Then, the morphological parameters of different types of fine aggregate particles were measured using image analysis techniques. This showed that the roundness of the particles decreases with decreasing density, and both the roughness and the aspect ratio increase. A regression model between the particle morphology parameters and characteristic viscosity was accordingly developed. The rheological properties of different types of mortars were examined. We find that as the particle density decreases, the yield stress and plastic viscosity decrease continuously, showing shear thickening behavior. Based on the coupled density-form effect, a modified Krieger-Dougherty model and Chateau-Ovarlez-Trung model are proposed. These proposed models result in more accurate predictions of plastic viscosity and yield stress for light and fine aggregate mortars.