Evaluation of Various Tack Coat Materials Using Interface Shear Device and Recommendations on a Simplified Device

The performance of pavement interface bonds affects the integrity of pavement structures. In current practice, tack coats are used to ensure sufficient bonding between asphalt concrete (AC) layers as well as AC and concrete or aggregate base layers. A tack coat is a light application of bituminous materials to an existing surface using a distributor to provide sufficient bonding between pavement layers (Asphalt Institute, 1989). In the past, several research studies were conducted at the Illinois Center for Transportation to evaluate the effectiveness of tack coats between two AC layers and AC and Portland Cement Concrete (PCC) surfaces. In this study, the shear strength of seven types of tack coat materials were evaluated, four of which were hot-applied tack coat products. The results show that hot-applied products have superior shear strength as compared to emulsion type products. A simplified shear testing configuration was also acquired and preliminary testing was completed to provide some recommendations for its future use by the Illinois Department of Transportation.IDOT-R27-SP34Ope