Study of function layer based on unbonded PCC overlays on old cement concrete pavement

Traffic loading and temperature variety are two main factors to induce reflective cracking of PCC overlay on old cement concrete pavement. With unbonded overlay design method, setting asphalt mixture function layer can effectively minimize the potential for reflection cracking. The finite element methods are used to analyze the influence of parameters of thickness and modulus of function layer on load stresses and thermal stresses in unbonded PCC overlays. The analysis results show that the recommended modulus is 1200~1400MPa, it should be as low as possible in permissible range, and reasonable thicknesses of function layer is 4~6cm.