Cement stabilized aggregate has been widely used as a base/subbase material in high-grade pavement in China. Cracking caused by dry and thermal shrinkage shortly after new construction is one of the major early distresses for cement stabilized base. Cracking spacing is usually accepted as a critical criterion to evaluate cracking distresses. The objective of this study is to develop a model to predict shrinkage cracking spacing for cement stabilized base. Firstly, material properties of cement stabilized aggregate were obtained from different kinds of physical property tests for theoretical analysis. Secondly, a finite element method (FEM) model was developed and verified to simulate the dry and thermal shrinkage cracking. Lastly, a sensitivity analysis of shrinkage stresses and shrinkage cracking was conducted by considering several shrinkage related factors including moisture loss rate, temperature difference, mixture modulus and the existence of overlays. It is discovered that the strength and shrinkage properties of cement stabilized aggregate could be predicted from the 7-day unconfined compressive strength. The prediction model is validated as an accurate tool to predict shrinkage stresses and spacing of cement stabilized base. It is also found that shrinkage cracking usually occurs in the middle of base surface at the beginning, and then extends down to the bottom. The base course with lower modulus might have less shrinkage cracking. There are no radical changes in shrinkage stresses for a base when an asphalt layer was placed on the top at early stage.
Abstract