Investigation of the bond and shear strength between open-graded friction course (OGFC) and dense-graded asphalt concrete

Open-graded friction course (OGFC) is a commonly used highway pavement material. The relatively low strength and low stiffness of OGFC create a concern on its interfacial bond and shear strength with the underlying dense-graded asphalt concrete (AC). The bond and shear strength may be particularly low if OGFC is directly placed on an existing milled AC layer during resurfacing operation. To address this concern, both the OGFC layer and the underlying AC layer are often resurfaced together in resurfacing operation, with the expectation that better bonding develops between two new layers. However, this practice may result in resource and monetary wastes if the bond and shear strength between the OGFC and milled AC layer are adequate. This paper reports research findings on the bond and shear strength issue based on in situ bond strength test, analysis of traffic-induced tractive force and interfacial shear stress, interfacial shear strength test, and site trials.