Improved Repair of Concrete Structures Using Polymer Concrete Patch and FRP Overlay

Concrete structures that are damaged due to cracking and spalling, associated with corrosion of reinforcing bars, are often repaired using shallow depth surface patches. Cracking and full or partial delamination of the patch repairs due to shrinkage and continued corrosion is generally unavoidable. The repair typically lasts only for a few years in corrosive environments associated with coastal regions or the use of deicing salts. To provide more durable patch repairs, the use of a fiber-reinforced polymer (FRP) fabric applied as an overlay on top of a traditional polymer concrete patching material was investigated. The FRP overlay can serve as a secondary reinforcement and act as a barrier against the diffusion of moisture and chloride ions, thereby improving the performance of the patch by reducing cracking and slowing down the corrosion process. Two-dimensional finite-element analysis was used to select a suitable FRP material and configuration for the overlay. The effectiveness of the proposed improved repair method was assessed using accelerated corrosion testing of rectangular concrete prism specimens with a polymer concrete patch and an FRP overlay. Reinforcement mass loss and expansive strains in concrete due to corrosion were measured on specimens with and without the FRP overlay. The measurements indicated reductions in concrete strains, crack propagation, and corrosion level when the FRP overlay was used. Three-dimensional finite-element analysis was conducted to understand the influence of using an FRP overlay on the concrete stress distribution and the arrest of cracking.