Implementation of Finite Element and Fracture Mechanics Based Reflection Cracking Models for Asphalt Concrete Overlay of Existing Asphalt Concrete Pavement in AASHTOWare Pavement ME Design

Abstract

The reflection of existing cracks from the underlying pavement is one of the primary modes of failure for rehabilitated asphalt concrete (AC) pavements with AC overlays. The AC overlay design philosophy is to delay the onset of reflection cracking or to eliminate it entirely. In recent years, rehabilitation designs are being optimized not just for cost effectiveness, but also to produce more reliable, sustainable, and environmentally friendly designs that require more detailed and sophisticated methodologies. The new finite element and fracture mechanics based reflection cracking models were developed under National Cooperative Highway Research Program (NCHRP) Project 1-41 to improve design methodology. The new models were generally compatible with the AASHTOWare Pavement ME Design (AASHTOWare) framework. The difference included the computation of critical pavement responses (i.e., stress intensity factors) and others, and thus modified. The modified models were calibrated and validated using Long-Term Pavement Performance projects. The calibration of reflection cracking models produced satisfactory goodness of fit with no significant bias. Thus, the modified reflection cracking models were successfully adapted and deployed in the AASHTOWare software to create a new improved AC overlay of existing AC pavement design methodology. This new methodology represents a paradigm shift from the traditional pavement design procedures. It significantly increases the capability of the pavement design software to simulate all the loadings experienced by AC overlay, estimate pavement responses, and predict reflection cracking based on pavement responses. This paper discusses the implementation of NCHRP 1-41 reflection cracking models for AC overlay of existing AC pavements into AASHTOWare software.