Effect of Pore Water Pressure on Response of Asphalt Concrete

Rapid traffic loading induces pore water pressure inside partially or fully saturated interconnected cracks and voids of asphalt concrete. The induced pore pressure contributes extra stresses within the pavement and accelerates crack evolution and propagation. Crack propagation facilitates diffusion of moisture through the solid phase and accelerates the degradation of the time-dependent stiffness and strength of asphalt concrete. Therefore, it is imperative to consider the coupled effects of pore water pressure, moisture diffusion, and mechanical loading on asphalt concrete pavement. The effect of pore water pressure was considered by using the effective stress concept inside deformable media. Biot’s approach was used and coupled to the nonlinear viscoelastic and viscodamage (moisture and mechanical) constitutive relationships for asphalt concrete. The models were implemented in PANDA, a finite element code developed at Texas A&M University. Capabilities of the proposed framework and constitutive relationships were demonstrated through the simulation of several realistic microstructural representations of asphalt concrete. The results of numerical simulations demonstrated how the effect of pore water pressure can intensify damage within asphalt concrete and reduce its strength. Therefore, this outcome emphasizes the importance of incorporating the effect of pore water pressure in investigating the response of asphalt concrete.