Cyclic stress–strain characteristics of red clay treated with permeable water-soluble polyurethane

Abstract

Red clay, a globally distributed type of chemical weathering soil, is commonly utilized as a road base in road infrastructure. However, due to its susceptibility to water and vibrations, it is prone to settlement and formation of potholes during operation, consequently leading to damage in the pavement structure. This paper employs a dynamic triaxial apparatus to simulate realistic traffic loads and investigates the dynamic properties of red clays treated with permeable water-soluble polyurethane (PSP). Additionally, a series of microscopic tests are conducted to elucidate the microstructural mechanisms of using PSP for improving red clay, as well as the microscopic deformation mechanisms of the PSP-treated red clay (PSP clay) under cyclic loading. The results provide detailed insights into the influence of soil moisture content and PSP content on key parameters, including the resilient modulus, damping ratio, permanent deformation, and strength of PSP clay after repeated loading. Moreover, the overall performance of PSP clay is evaluated under varying loading amplitudes and confining pressures. These results are complemented and interpreted in conjunction with the findings from the microscopic tests. The findings reveal that the inclusion of PSP improves the strength of the soil skeleton by enveloping and interlocking with the clay particles. Furthermore, it is observed that the engineering properties of high-moisture-content red clay soils can be significantly improved with low levels of PSP. Under specific conditions, repeated loading further compact the PSP clays, thereby enhancing their mechanical properties. The experimental findings presented in this study are of utmost importance for the improvement and application of red clays through the utilization of rapid solutions, such as PSP.