Evaluation of bond strength between hot mix asphalt and stone mastic asphalt surfacing layers

Abstract

Poor bonding between asphalt layers cause many distresses, and the most typical problem is the slippage failure. This failure usually occurs when there are exists insufficient bond between the interfaces of the two layers in contact. Therefore, sufficient tack coat is needed to provide greater bonding strength between pavement layers to be able to withstand traffic and environmental stresses. Thus, this study is conducted to evaluate the influence of tack coat, application rates, and layer thickness on the interface bond strength between hot mix asphalt and stone mastic asphalt. A total of three tack coat materials have been used, which are RS-1K and RS-2K and RS-2KL. These tack coat materials were applied at three different application rates, 0.25 l/m², 0.40 l/m² and 0.55 l/m² which represent low, medium and high application rates respectively in accordance with the JKR specification. Direct shear test has been conducted at shearing rate 1 mm/min and shearing platens 5 mm gap. Analysis obtained shows interface shear strength increased as layer thickness and application rate increase. High viscosity of tack coat produced high interface shear strength than low viscosity tack coat.