A framework for predicting top-down crack initiation and growth for flexible pavements

ABSTRACT

Top-down cracking (TDC) is recognized as a significant form of distress in asphalt pavements. While the NCHRP project 1-52 introduced a mechanistic-empirical (ME) predictive model for TDC, this model was found to be less accurate in certain traffic conditions—overpredicting crack initiation in sections with medium to low traffic and underpredicting in high-traffic sections. To enhance the precision of TDC predictions, a new fracture-mechanics-based framework has been developed. This improved framework employs a Hot Mix Asphalt (HMA) fracture mechanics methodology, resulting in a marked enhancement in the accuracy of predicting crack initiation times when compared to the original sub-model from NCHRP 1-52. The new framework also incorporates a novel aging model for the asphalt mixture, ensuring more precise inputs for the crack propagation model. The propagation prediction sub-model has been refined by implementing a J-integral-based Paris’ law developed in the NCHRP 1-52 project. The efficacy of this updated framework was rigorously tested on eighteen diverse pavement sections across various geographic locations, with well-documented performance history and material properties. The outcomes indicate that the predicted initiation and propagation of TDC closely align with actual field observations, demonstrating the robustness and improved reliability of the new model.

KEYWORDS:

• Asphalt pavement
• traffic load spectra
• fracture mechanics
• top-down cracking
• crack initiation
• crack propagation

Disclosure statement

The authors have no conflict of interest to declare.

Additional information

Funding

The Authors would like to thank the Swedish Transport Administration for the financial support.