Shear Strength between Poroelastic Road Surface and Sublayer with Different Bonding Agents

Abstract

Insufficient bonding strength between a poroelastic road surface (PERS) and a sublayer usually induces premature delamination failure. The objective of this paper was to investigate the shear bonding strength of the PERS-sublayer interface with different bonding agents and develop polyurethane-bound grain (PUG) as an alternative bonding agent. The inclined shear test was utilized to measure shear bonding strengths of control (without bonding agents) and interface-treated samples. The effects of polyurethane content within PERS, sublayer type, temperature, and freeze-thaw conditions on PERS-sublayer shear bonding strengths were investigated for control samples. Shear bonding strengths between the PERS and sublayer with a PUG layer were compared to those with epoxy asphalt and polyurethane for interface-treated samples. It was found that shear bonding strengths between PERS and asphalt-bound sublayers substantially decreased, with the increase of temperature or after one freeze-thaw cycle. Shear bonding strengths between PERS and asphalt-bound sublayers were smaller than the ones between PERS and cement-bound sublayers, regardless of polyurethane content, temperature, or freeze-thaw condition. The PUG layer enhanced PERS-sublayer interface bonding and achieved comparative bonding strength to epoxy asphalt, which was greater than the bonding strength brought by pure polyurethane. A PUG layer with 7% polyurethane produced more than 1.5-MPa shear bonding strength at 6°C for the grain size considered in this study.