Developing a fatigue fracture model for asphalt overlay reinforced with geogrid
This study examines the influence of the most important parameters on delaying reflection cracking in geogrid reinforced overlay in bending mode, employing a large scale experimental set up. The effects of grid stiffness, tensile strength, coating type, amount of tack coat, overlay thickness, crack width and stiffnesses of overlay and existing asphalt concrete on reinforced asphalt overlay was investigated. Results indicate that the cracked layer and overlay moduluses have strongest influence on reduction of reflective cracking. Also, a fatigue fracture model for reflection cracking based on modified Paris law for fracture mechanic model with linear viscoelastic correspondence principle in mode I was developed. It was found that this engineering fracture mechanics model was an efficient method of determining the fatigue damage process. Based on Schapery's theory, regression equations were developed to estimate fracture parameters. These equations can be used to predict the crack growth rate in the design of asphalt overlay against reflective cracking.