Research on dynamic load strength criteria of cement stabilized macadam based on strength tests under simple stress states

Establishing durable asphalt pavement is crucial for realizing green roads. The strength model is the calculation basis for the design of durable pavement structures. Existing strength models for cement-stabilized macadam (CSM) typically derive from static load strength tests, neglecting the impact of loading rates. Firstly, this study validated the strength model under three-dimensional stress state using true triaxial compression test data of CSM and determined the parameters of the strength model. And by conducting uniaxial compression (UC), direct tension (DT), and indirect tensile (IT) strength tests under static and dynamic load conditions, simplified strength model parameters were determined under different loading modes. Then, we calculated the strength under a three-dimensional (3D) stress state of CSM based on simplified strength models with different loading rates, studied the relationship between the strength and loading rate. Finally, the relationship between the parameters of the simplified strength model under dynamic load conditions and the loading rate (v) was established, the dynamic strength model under a 3D stress state of CSM was determined. Using the correlation between driving speed and loading rate, the strength models of CSM for different grades of highways were determined. The results indicate that there is a significant difference between triaxial compression strength and the strength calculated by the simplified strength model under different loading rates. The strength with a loading rate of 50 MPa/s can reach about twice the triaxial compression strength. As the v increases, the strength under the 3D stress state increased in a power function. The strength model parameters under 3D stress state of CSM were related to the v as a linear relationship. Due to different driving speeds, the strength models of CSM of different levels of highways varied. This work makes the strength models of CSM more complete and improves the accuracy of CSM layer design.