Study on the steady-state and dynamic rheological characteristics of five clayey materials

Understanding the rheological properties of clayey soils is significant for construction and geotechnical engineering, as these properties influence the stability and performance of building materials and structures. This study offers a new prospective for the rheological behavior of soils with water content near the liquid limit. Steady-state and dynamic rheological tests were conducted on kaolin, montmorillonite, and other three mixed clays of them at different water contents. In addition, microstructural analysis was performed to explain the microscopic mechanisms influencing the rheological responses of clays. The results show that for all the clays, the yield stress decreases with increasing water content. With the increase of shear rate, the viscosity first decreases rapidly and then decreases slowly. Clay mixtures exhibit greater microstructural stability than pure kaolin and montmorillonite, resulting in higher yield stress. Furthermore, dynamic shear testing provided insights into energy storage and loss modulus of clays near the solid-liquid transition phase. The proposed dynamic yield stress model effectively describes yield stress variation with the liquid limit under dynamic loading, relevant for assessing soil liquefaction potential and seismic resilience of structures. These findings offer valuable guidance for optimizing soil behavior in construction and enhancing structural performance in clay-rich regions.