Strain Energy Release Rate at Interface of Concrete Overlaid Pavements

A new method for calculating energy release rate (ERR) at interface of concrete overlaid pavements is proposed using crack closure and the nodal force technique. This method transforms a three dimensional pavement system into a two dimensional interfacial crack model via a theoretical conversion. The interfacial ERRs of steel fibre reinforced, roller compacted, polymer modified concrete overlay pavement subjected to vehicular load were calculated and compared with the measured interfacial fracture toughness of the bi material. It was found that the ERRs considerably decrease with the increase in overlay thickness and elastic modulus of foundation. Thin overlays (less than 100mm) should not be considered in overlay pavement design to avoid interfacial delamination induced by heavy vehicular loading. For a typical overlay pavement system subjected to complex vehicular loads, an interfacial crack suffers mainly from damage due to mode I, opening, compared to mode II, sliding, while mode III, tearing damage is negligible.