Abstract
After a period in service, the degradation of concrete structures is unavoidable. For large concrete areas, thin bonded cement-based overlay is a suitable rehabilitation technique. However, the durability of such repairs sometimes remains difficult to predict, especially because of the variable conditions inherent in the work site. The present paper, associating experiment and simulation approaches, focuses on some key parameters influencing debonding propagation along the concrete overlay-substrate interface under static loading. Based on the cohesive crack concept, a model using identified and quantified parameters was built and validated by comparing numerical and experimental results. Different factors having an impact on the interface debonding were then investigated. For the overlay material, the parameters analysed were autogenous shrinkage, Young's modulus, tensile strength and types of fibre-reinforcement. For the curing conditions, the relative humidity of the surroundings was taken into account. Concerning the overlay-substrate interface, the fracture energy and bond defects were considered. The model predictions allowed the influence of each factor to be evaluated. In particular, the effect of shrinkage on the durability of the composite specimens was clarified. The importance of the capacity of fibres to control debonding by restraining crack opening was proved.