Field Rutting Performance of Various Base and Subbase Materials under Two Types of Loading

Seven full-scale field testing sections were built to evaluate the in situ performance of raw blended calcium sulfate (BCS), stabilized BCS, stabilized reclaimed asphalt pavement (RAP), and stabilized soil as base and subbase materials. Two types of load tests were used to evaluate test sections: cyclic plate load test and rolling wheel load test. The differences in pavement response to cyclic plate and rolling wheel loads were identified. The results indicated that the conventional equivalent modulus of elasticity, where only the thickness of individual layers is considered, is not a good performance indicator. However, its modified formulation proposed here provides the means to account for the relative position of individual layers and turn the conventional equivalent modulus of elasticity into a good performance indicator. The rut depths for the rolling wheel load were much higher than those for the cyclic plate load in all test sections. The difference can be as much as three to seven times between these two types of loading. As such, the effects of principal stress rotation and lateral wander on the permanent deformation in pavement need to be addressed in the design. The results of in situ evaluation showed that the 120-grade ground granulated blast furnace slag stabilized BCS is a good candidate as an alternative to conventional stone base.