Influence of residual stress on PCC pavement potential cracking

The load-induced stress and enviromental stress (curling and warping stress) are considered for PCC pavement slab cracking analysis in many design methods. However, the residual stress is not considered in design. Cement concrete slab volume changes are prevented by the structure surrounding the concrete or stable phases such as aggreagates will cause residual stress developing, and the residual stress may lead to early cracking in slab even before traffic load applying on it. Early cracking in cement concrete occurs frequently, however, currently residual stress are not considered in rigid pavement design method. Therefore, it is impossible to know the potential cracking of PCC pavement without knowing the residual stress level in a concrete pavement. In this paper, core-ring drilling is applied to release the residual stress in concrete pavement slab based on refering to measurements method in metal engineering. In the process of drilling strain gages are used to record the variation of stains on the surface of concrete slab. From test results, core-ring drilling can release stress and this method appears to be valid for measuring residual stress in concrete. Residual stress on the concrete slab surface can arrive at 7~16.8% of concrete flextual strength approximately based on finite elment analysis of core-ring dirlling process.From the tests results and theoritical results if the residual stress is considered, PCC pavement top-down cracking risk will increase, which will influence the damage style of PCC pavement.