Evaluation of the Interlayer Stress-Absorbing Composite (ISAC) to Mitigate Reflective Cracking in Asphaltic Concrete Overlays

The problem of reflective cracking through an asphaltic pavement overlay results in high maintenance costs and rough rides to the driving public. In this experimental project, a product called the Interlayer Stress-Absorbing Composite (ISAC), a reflective cracking retardant, was installed and evaluated. According to the manufacturer, the ISAC will extend the life of an asphaltic overlay placed over a concrete pavement by retarding reflective cracking. The scope of this project included milling two inches from the concrete pavement and replacing it with a two-inch asphaltic overlay. The ISAC material was placed over cleaned and sealed transverse joints prior to placement of the asphaltic overlay. During placement of the overlay, directly after the hot roller finished rolling the overlay, a bump was visible along each transverse edge of the ISAC fabric. At the completion of rolling operations, the transverse bumps were only visible along one edge of the ISAC fabric. Due to the transverse bumps in the overlay, the overlay and the ISAC fabric were removed and the test section was repaved without the ISAC. The manufacturer explained that the likely cause of this problem was due to the old age of the ISAC material used. The age of the ISAC was almost three years, which caused the ISAC to wrinkle. According to the manufacturer, they usually don’t sell any of the ISAC products beyond thirty days old. Due to the removal of the ISAC system, an in-situ performance evaluation was not possible and this study was canceled. Since the material was removed, a cost analysis was not performed.