Revitalizing an Existing Reinforced Concrete Bridge: Deficiencies, Repair Techniques and the Role of FRPs

Italy, known for its large historical and cultural building heritage, boasts a vast network of reinforced concrete (RC) bridges that plays a crucial role in connecting various regions. However, over the time and due to the exposure to harsh environmental conditions, these bridges have exhibited structural deficiencies, including deterioration, cracking, and loss of load- carrying capacity. In a deeper scale, corrosion of the steel-reinforcement due to chloride ingress and carbonation are both evident. The latter leads to the deterioration of the concrete, the loss of the bond between steel-reinforcement and concrete, and the reduction of the structural integrity. Furthermore, bridges may experience excessive deflection, which compromise their serviceability performance. To address these drawbacks, a range of repair techniques have been employed. These include, among the others, conventional methods such as crack sealing, surface patching, and cathodic protection to mitigate corrosion. On the other side, advanced materials like fiber-reinforced polymer (FRP) have been relatively recent favored. It consists of high-strength fibers embedded in a polymer matrix (generally epoxy-based), which have gained prominence as a viable solution for the structural rehabilitation of RC-bridges. In fact, FRP offers several advantages including a high strength-to-weight ratio, corrosion resistance, and excellent durability. FRP-composites can be used for strengthening and retrofitting bridge components, such as beams, columns, slabs, and shear walls, to enhance their load-carrying capacity and structural performance. Various FRP- based rehabilitation techniques are commonly employed in Italy, including externally bonded FRP sheets/strips, near-surface mounted FRP rods, and FRP wraps for the confinement of concrete columns. The techniques involve the application of FRP materials to the external or internal surfaces of deteriorated elements, effectively enhancing their strength and/or stiffness. The present paper aims to report a success case-study concerning the external strengthening of a RC-bridge carried out using FRP-materials in the perspective of demonstrating the validity of the FRP-application for bridge strengthening and maintenance based on a proper design and time-dependent visual observations.