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

Reflection cracking is one of the most common forms of distress in asphalt concrete (AC) overlay of existing concrete pavements. Due to repeated traffic loads and temperature cycles, these cracks in the existing pavements propagate through the AC overlay layer, thus reducing service life. The AC transverse cracking model in the Mechanistic-Empirical Pavement Design Guide (MEPDG) developed under the National Cooperative Highway Research Program (NCHRP) Project 1-37A does not account for reflection transverse cracking. Recognizing this deficiency, fracture mechanics-based AC reflection transverse cracking models for existing concrete pavements were developed by Texas Transportation Institute (TTI) under NCHRP Project 1-41. The existing concrete pavements include intact jointed plain concrete pavement (JPCP), intact continuously reinforced concrete pavement (CRCP), and fractured portland cement concrete (PCC) pavement. These reflection transverse cracking models were generally compatible with AASHTOWare Pavement ME Design (Pavement ME) framework. As much of the theory, concepts, assumptions, and inputs in the NCHRP 1-41 procedure as possible were implemented into Pavement ME. The difference included the computation of critical pavement responses [i.e., stress intensity factor (SIF)] and others. The finite element model was replaced by artificial neural network (ANN) models to increase computational speed and efficiency. The calibration of reflection transverse cracking models produced satisfactory goodness-of-fit statistics with no significant bias. This paper describes the implementation and national calibration of the NCHRP 1-41 reflection transverse cracking models for AC overlay of existing concrete pavements into Pavement ME.