A micromechanical approach to computing linear and nonlinear moisture and temperature stresses in concrete pavements

Temperature and moisture gradients can cause significant tensile stresses in concrete pavement, which can lead to cracking without the occurrence of any mechanical loads. Currently, most analysis and design methods assume linear distribution of thermal and hygrothermal strains through the slab depth, which usually underestimates the critical tensile stresses in the concrete pavement. A novel micromechanical approach to calculate the moisture curling stresses in concrete pavements based on measured relative humidity gradients is proposed. In this approach, the loss in moisture from the cement microstructure creates a negative pressure in the concrete capillary pores, which ultimately produces the bulk concrete shrinkage and moisture curling (differential shrinkage). The hygrothermal strain at each point in the slab depth is calculated through the Kelvin-Laplace and Mackenzie equations, which provide a basis for calculating the moisture curling stresses at any time, similarly to the formulation for calculating temperature curling stresses. The evolution of stresses due to nonlinear temperature and moisture gradients are calculated based on field measurements with consideration for the tensile creep of concrete. The proposed formulation allows for a concise analytical solution to evaluate the effects of moisture and temperature curling on slab size and the concrete's material constituents.