Development of an overlay design model for reflective cracking with and without steel reinforcing nettings

Hot-mix asphalt (HMA) overlays are typically used to rehabilitate cracked pavements. Cracks in the existing pavement move continuously due to thermal expansion and traffic loadings, and then propagate upward to the new pavement surface causing reflective cracking. Steel reinforcing nettings have been used successfully in Europe for the past two decades to improve HMA resistance to reflective cracking. By summer 2002, steel reinforcements were used in at least 15 projects in the US. To investigate the potential of steel reinforcing nettings to mitigate the reflection of cracks, a theoretical approach is presented based on Three-Dimensional (3D) finite element modeling. The 3D finite element model accurately simulates steel reinforcement as a non-homogeneous interlayer with openings. Both the crack initiation and propagation phases for the reinforced and non-reinforced cases were considered. Results of this analysis were then used to develop design equations that may be used to predict the overlay service life against reflective cracking with and without steel reinforcement. In general, based on finite element analysis (FEA), steel reinforcement was found to improve the overlay service life by a factor ranging from 50 to 90 percent depending on the overlay thickness and the pavement structural capacity.