Evaluation on Moisture Susceptibility of Stone Mastic Polyurethane Concrete

Abstract

Stone mastic polyurethane concrete (SMPC) is a new pavement material that is mixed at room temperature and has excellent pavement performance. To accurately evaluate the moisture susceptibility of SMPC with varying polyurethane content, the trend of residual splitting strength was analyzed and quantified through laboratory freeze-thaw splitting tests. Then scanning electron microscopy (SEM) was used to characterize the microscopic morphology of the fracture surface of SMPC samples after freeze-thaw cycles. Next, the porosity distribution was quantified using MATLAB version 2015b, and the strength attenuation mechanism was analyzed. Finally, the relationship between residual splitting strength, freeze-thaw cycles, and varying polyurethane content was established by the grey Verhulst model. The results showed that the splitting strength increased with increasing polyurethane content. It also increased with increasing polyurethane content at the same number of freeze-thaw cycles. In addition, at the same polyurethane content residual splitting strength decreased with the increase in the number of freeze-thaw cycles and reached stability after three cycles. The SEM scanning images were analyzed by MATLAB, and it was found that the increase in porosity caused by interface failure between the aggregate and the polyurethane binder was the main reason for the decrease in SMPC residual splitting strength. Finally, the established relationship model was used to fit the residual splitting strength at different freeze-thaw cycles, elucidating the connection between residual splitting strength and various freeze-thaw cycles.