Curling and Curling Stresses of New Concrete Pavements

Curling generally results from the temperature differential across the concrete slab thickness and may induce undue stresses in newly placed slab. This study deals with the finite element (FE) analysis of curling stresses and field measurement of curling of a newly built jointed plain concrete pavement. The FE analysis was performed with a software program, ANSYS. The test section was modeled as a three-layer system with 300 mm concrete slab, 100 treated drainable base, and 150 mm lime-treated subgrade. All layers were assumed to be linear elastic. Temperature data was collected at five different depth locations across the concrete slab with digital data loggers. Curling was measured on five different days with a simple setup. The effect of temperature nonlinearities across the slab thickness was also examined. The results show that both upward and downward curling increase as the temperature differential increases. The maximum stress resulting from the combined effect of curling and traffic loading due to positive temperature differential is higher than that due to the negative temperature differential of same magnitude. Since temperature differential has a significant influence on curling, both curling and curling stresses can be mitigated at an early age with enhanced curing.