Bond Performance of the Slurry Infiltrated Fiber Concrete Overlay on Normal Strength Concrete Substrate

Many concrete structures require strengthening or repair and a significant method of strengthening the Reinforced Concrete (RC) members is to add a concrete jacket. A type of concrete known as Slurry-Infiltrated Fiber Concrete (SIFCON) has come into use. SIFCON is a unique form of Fiber-Reinforced Concrete (FRC) known for its superior mechanical properties. The effectiveness of upgrading the RC members through jacketing depends on several factors, the most important of which is the bond performance between the substrate and overlay layers. This study examined how various factors influence the bonding performance between the SIFCON overlay and the Normal Strength Concrete (NSC) substrate. The research investigated the effects of surface preparation methods, types of bonding agents, and steel fiber geometry. Three tests were conducted to evaluate the bond strength: the Slant Shear Test (SST), Tensile Bond Test (TBT), and Flexural Bond Test (FBT). The surface preparation methods ranked from best to worst as follows: Grinding (G), Sandblasting (S), and Diamond Cutting (DC). The increase in the bond strength depended on the type of bonding agent and the surface preparation method. When the failure mode changed from Bond Interface (BI) to both BI and Weaker Concrete (BI-WC) or from BI-WC to WC, the increase was noticeable. If the failure mode shifted directly from BI to WC, the growth was significant. However, if the failure mode remained the same, the increase was minimal.