Estimation of stress at interface of asphalt surface and rigid base of composite pavement

Abstract

Composite pavement, with asphalt overlaid on rigid base, can achieve a great structural advantage if interfacial bonding between the two layers can be maintained. If the interfacial stress exceeds the bonding strength of the tack coat material, the asphalt surface and rigid base can become debonded. Once debonding occurs, a high level of tensile stress will develop beneath the asphalt layer under traffic loading and subsequent development of cracks will occur. Conventional concrete, roller-compacted concrete and cement-treated concrete can be used as the rigid base of composite pavement and curling in this layer may lead to normal tensile stress at the interface. In addition, traffic loading as well as braking at the surface may develop the shear stress at the interface. These interfacial stresses are needed to evaluate bonding efficiency. Therefore, this study estimates numerically the interfacial tensile and shear stress due to the temperature differential in the rigid base and due to traffic loading, respectively. The study found that stress due to traffic loading is more important than that due to temperature differential. The tensile stress produced by curling in the rigid base can range from 0·05 to 0·16 MPa. Also, the combination of vertical and horizontal loading of various axle types can generate shear stress from 0·02 to 0·56 MPa.