Abstract
In July 2007 the Massachusetts State Highway Department (Mass-Highway) began a pavement rehabilitation project involving the placement of hot-mix asphalt (HMA) over a section of portland cement concrete (PCC) pavement on Interstate 495. The pavement rehabilitation consisted of a 50.8-mm (2-in.) thick leveling course, followed by a 25.4-mm (1-in.) thick reflective crack relief interlayer (RCRI) and an overlay of another 50.8-mm (2-in.) thick intermediate course consisting of a dense-graded HMA mixture that was identical to the leveling course. Within approximately 2 months after placement, reflective cracking was observed in the area where only the initial 50.8-mm-thick leveling course had been placed. Approximately 6 months after the section that included the RCRI had been placed, reflective cracking was also observed. This paper summarizes a field and laboratory forensic effort that was aimed at determining the cause of the early reflective cracking on Interstate 495 in Massachusetts. Field testing, with the falling weight deflectometer as well as coring of PCC pavement, was used to assess the PCC joint performance in the vertical and horizontal deflection modes. Laboratory testing was conducted on laboratory-prepared HMA and evaluated for cracking resistance under vertical and horizontal deflections and for test temperatures that simulated field conditions. A general framework is introduced that can be used to assess the compatibility of different HMA and RCRI mixtures intended for use on composite pavements during the mixture selection and design phase before field placement.