Investigation into the Top-Down Cracking of Asphalt Pavements in North Carolina

摘要

Top-down cracking has become a commonly reported cracking mechanism in asphalt pavementsworldwide. In top-down cracking a crack initiates at the surface of an asphalt concrete pavementand propagates to the bottom of the asphalt pavement layer. Because the location and governingstate of stress for top-down cracking are different than for bottom-up cracking, pavementcracking performance analysis needs to be robust enough to account for the complexmechanisms that are involved in top-down cracking. This study applies the viscoelasticcontinuum damage finite element model to the evaluation of two pavement sections in NorthCarolina where top-down cracking has been identified. Small specimen geometries are used toperform simplified viscoelastic continuum damage (S-VECD) testing on individual asphaltlayers obtained from field cores. The S-VECD model and the Fourier finite element program areused together (as the VECD-FFE model) for pavement cracking performance simulations andemploy the structure and layer material properties obtained from the two study pavements. Thesimulation results clearly support the propensity of these pavements to exhibit top-down cracking.In addition to this laboratory testing and analysis, the deflection-based method suggested byUhlmeyer et al. is applied to the data obtained from pavement sections with known crackinitiation locations in order to investigate the method’s validity. The Uhlmeyer method uses theAREA parameter that is determined from falling weight deflectometer deflections, and pavementthicknesses. The analysis results show a clear difference in the AREA versus pavement thicknessrelationship between the pavement sections with top-down cracking and those with full-depthcracking.