Effects of Transverse Cracks on the Backcalculated Layer Properties of Asphalt Pavements from Non-destructive Testing Data

Falling weight deflectometer (FWD) is widely accepted as a non-destructive testing system for pavement evaluation. This study aims to investigate and evaluate the effects of transverse cracks on the backcalculated layer properties of asphalt pavements from FWD data. 3D finite element (FE) models were developed to simulate various intact and transverse-cracked pavements under an FWD loading history, and the FE models were validated with the field measurements. FWD deflection data from FE models were utilized to backcalculate layer properties using a dynamic viscoelastic backcalculation procedure. The backcalculated results from transverse-cracked pavements were compared to those from intact pavements. The results indicate that the backcalculated asphalt concrete (AC) and base layer moduli of thermal-cracked pavements are significantly different from those of intact pavements. The normalized difference of backcalculated moduli between intact and thermal-cracked pavements ranges from − 68 to 23% for AC layers, while it ranges from − 57 to 36% for base layers. The backcalculation analysis on FWD data of thermal-cracked pavement can lead to an overestimation of AC modulus and an underestimation of base modulus although AC layer is weakened by thermal cracks, which is counter-intuitive to what one would expect that crack in a structural layer will result in a reduction in backcalculated modulus of that layer. Meanwhile, backcalculation procedure failed to analyze the FWD data of reflective-cracked pavements. These observations indicate that backcalculation analysis cannot accurately evaluate the layer conditions and structural performances of transverse-cracked asphalt pavements.