Evaluation of Performance of Void-Reducing Asphalt Membrane and Tack Coat on Asphalt Mixtures’ Longitudinal Joints

The longitudinal joint is one of the most crucial parts of asphalt pavement construction becuase several types of distress of the pavement can occur if the target density does not meet at the joint. A low density of asphalt pavement causes the pavement at the joint to be more exposed to water penetration, accelerating the rate of deterioration. To address this issue, asphalt agencies use various construction techniques and innovative materials to improve the joint’s performance. Void-reducing asphalt membrane (VRAM) is an innovative adhesive liquid that consists of an asphalt binder, an elastomeric polymer, and a wax modifier. In this study, field cores were collected from an Indiana state road to evaluate the VRAM and tack coat performance at the joint. Semicircular bending Illinois flexibility index (SCB-IFIT) and modified pulloff strength tests were performed to investigate the fatigue resistance and bond strength of VRAM and tack coat at the joint. Digital image analysis confirms that VRAM can migrate up to 15.88 mm ($5/8\mathrm{in.}$) from the interface. In addition, the pulloff strength test reveals that the interface bonding of the pavement containing VRAM is less than the pavement containing tack coat at low and intermediate temperatures. One of the key findings from the SCB-IFIT test is that the flexibility index of VRAM-containing pavement is around eight times higher than tack coat–containing pavement. Moreover, the fatigue cracking resistance of the VRAM-containing pavement is higher than the laboratory-prepared asphalt mixtures with PG 64-22, PG 70-22, and PG 76-22.