Non‐destructive evaluation of longitudinal cracking in semi‐rigid asphalt pavements using FWD deflection data

In order to select the optimal treatment strategy for cracked pavements, the cracking conditions should be accurately investigated and evaluated. In this study, the effects of longitudinal cracking on falling weight deflectometer (FWD) deflections were investigated, and a rapid and non-destructive approach was accordingly proposed to evaluate the longitudinal cracking severity using FWD data for semi-rigid pavements. 3D finite element models were developed to simulate various intact and cracked pavements to compute the surface deflections under FWD loading. Two cracking types, namely, cracking in asphalt concrete layer (AC cracking) and cracking in both AC and cement-treated base layers (AC + CTB cracking), were considered. In most cases analyzed, the deflections of cracked pavements are greater than those of intact pavements, and they are only slightly smaller than those of intact pavements in other cases. The effects of longitudinal cracking on deflections increase with increasing crack width and decreasing distance between the crack and the loading center, and longitudinal cracking generally has greater influences on the pavement with a thicker AC layer and weaker subgrade. The effects of AC + CTB cracking on deflections are significantly greater than AC cracking, especially for the cracks near the loading center, and the influences of both AC cracking and AC + CTB cracking are negligible when the deflections are measured more than 1.8 m away from the crack. Accordingly, a rapid and non-destructive approach was proposed to distinguish the AC cracking and AC + CTB cracking using FWD data for semi-rigid pavements.