Forward calculation method to determine built-in thermal curling of concrete slabs

The residual stress and built-in curling would result in the multi-cracking modes in PCC slab and have influences on the long term service behavior of JPCP. Different from the current approaches to determine built-in curling in cement concrete slabs, a new forward calculation method is proposed. User subroutines to compute temperature field and stress field were developed. Tensile and compressive creep behavior of early age concrete were separately characterized. The established model can predict the temperature field and stress field in concrete pavement since slab cast. Results indicate that built-in thermal curling is position-dependent and distributes as residual stress and residual curling. Residual stress and residual curling in slabs normally stabilize after 30 days. Curling reset technique is adopted to convert the residual curling to residual stress. Furthermore, the residual stress along depth is changed to its equivalent linear temperature gradient. In the end, measured data from full scale test road slabs are employed to evaluate the feasibility of the forward calculation method. When restrained by adjacent slabs, built-in curling behaves more as residual curling and the peak value appears in the area near the joint cutting.