Evaluation of Influence Factors on Crack Initiation of LTPP Resurfaced-Asphalt Pavements Using Parametric Survival Analysis

Survival model with Weibull hazard function was used to evaluate the influence of different factors on the crack initiation of resurfaced asphalt pavement. Data from Specific Pavement Study 5 experiments of the Long Term Pavement Performance (LTPP) program were used to conduct the analysis. The initiation time of four types of cracks including alligator (fatigue) crack, longitudinal crack on wheel path, non-wheel path longitudinal crack, and transverse crack was evaluated. Analyzed factors include overlay thickness, total pavement thickness, pretreatment pavement serviceability, traffic volume, freeze index, mixture [whether reclaimed asphalt pavement (RAP) is used], and whether milling is performed before overlay. It was found that traffic level was a significant factor for all four types of cracks. High traffic level accelerated the initiation of cracking. Thick overlay delayed the initiation of cracking except for the non-wheel path longitudinal crack, which is mainly caused by poor construction. Total pavement thickness only retarded the initiation of wheel path longitudinal cracking. Incorporating 30% RAP in the overlay accelerated the initiation of early-age fatigue cracking; however, it was not a significant cause for severe fatigue cracking. Severe freeze-thaw conditions accelerated the occurrence of non-wheel path longitudinal and transverse cracks; milling before overlay significantly retarded the occurrence of the two types of cracks.