Investigation of intrinsic de-bonding in bonded concrete overlays: Material characterisation and numerical Study

This study investigates the evolution of intrinsic interfacial de-bonding of Roller Compacted Steel Fibre Reinforced Polymer Modified Concrete (RC-SFR-PMC) bonded on substrate Ordinary Portland Cement Concrete (OPCC), using both experimental and numerical techniques. The relative effects of evolving material inhomogeneity and composite dimensional stability during curing was studied as a function of overlay structural scale, using a 2D plane strain Interface Cohesive Zone Model (ICZM). The effects of creep coefficient on interface restraint capacity and ensuing cohesive zone length were clearly evaluated. The results showed that the applied curvature due to the measured shrinkage strain was inadequate to cause critical de-bonding. In the FEA results, while the rate of interface energy release generally varies as a function of the bi-material relative stiffness and overlay structural scale, it is also evident that the two variables lose effects as the overlay structural scale approaches 0.50. The overall indicative trend shows that the rate of energy release in compliant overlay when relative stiffness( α<0) is higher than when α>0. Therefore, a more compliant overlay typically exhibits less relative restraint to bending induced de-bonding.