AC layer fatigue damage analysis and reflective cracking control of CRC plus AC composite pavement

The current continuous reinforced concrete composite asphalt pavement (CRC + AC) design method in China does not consider the effect of the asphalt concrete (AC) layer on the longitudinal reinforcement rate of the continuous reinforced concrete (CRC) layer. To address such issues, a finite element model of CRC + AC using continuum damage mechanics theory and finite element method was established. The most unfavorable working condition and the location of the greatest damage by comparing the damage distribution under different working conditions were determined. To resolve the limitations of traditional design methods of CRC + AC composite pavement, criteria for the microcrack width of the CRC layer under different AC layer thicknesses were proposed, based on the combined effects of AC layer thickness and CRC layer microcrack width on the damage of the AC layer. The results suggest that the left lane vehicles braking and the right lane vehicles driving at a constant speed are the most unfavorable working conditions, with the greatest degree of damage found on the lane divider of AC layer. meanwhile, the microcrack width should be below 0.64 mm to mitigate the risk of Top-Down cracking and reflective cracking. Additionally, the CRC plate crack width control standards are provided for AC layer thicknesses ranging from 4 cm to 14 cm.