Characterization of Substrate-to-Overlay Interface Bond in Concrete Repairs: A Review

Repair and strengthening of concrete structures have become more important with the aging of existing infrastructure and the rising reconstruction costs. One of the popular and economical methods to extend the service life of concrete structures is to use bonded material overlays. The material mismatch between the substrate and overlay makes the substrate-to-overlay interface bond weaker and more susceptible to damage. Hence, the performance of such composite bimaterial structures depends on the soundness of this interface bond. This paper reviews the literature on bonded concrete repairs, focusing on existing test methods to characterize the interface bond properties (e.g., strength, fracture energy, etc.). Furthermore, the paper discusses substrate surface preparation techniques, overlay materials, and durability, and it makes recommendations for future research. To the authors' knowledge, there are no reviews that critically evaluate the different types of test methods available for bonded concrete repairs, although there is an abundance of test methods available. The authors believe this document will aid in test selection, material selection, and surface preparation for concrete repairs.