Validating Concrete-to-Concrete Interfacial Modeling through a Multiparametric Experimental Campaign

The aging and deterioration of existing RC structures are often addressed with jacketing of weak structural members. This study proposes a blend of numerical methods to precisely simulate the interfacial bond performance in composite sections consisting of fresh and hardened concrete layers. A comprehensive experimental campaign of 75 direct shear tests was conducted, focusing on three key contributors to bonding strength: (1) surface roughness, (2) application of a bonding agent, and (3) the impact of interfacial compressive normal stresses due to confinement or external forces. The results indicated, as anticipated, that roughening benefits bonding capacity, and the bonding agent’s contribution was evident only on smooth surfaces. Regarding the effect of normal stresses, bonding performance was enhanced only up to a certain load. To further and more accurately analyze contact behavior, a novel numerical simulation integrates cohesion, friction, and plastic damage models in computer simulation and employs contact elements under explicit dynamic analysis. The proposed modeling technique efficiently accounts for various parameters, including roughness, concrete properties, and pressure on the interface, offering a versatile tool for analysis. Furthermore, a generalized optimized model has been proposed to complement the analytical simulations and categorize surfaces as either smooth or rough, with acceptable convergence, providing a practical, and robust approach for concrete-to-concrete contact modeling.