Corrosion of Thermo-Mechanically Treated (TMT) Mild Steel in Reinforced Concrete Structures: Mechanical and Structural Implications

Reinforced concrete (RC) remains the most widely used construction material due to its combined compressive and tensile strength principally due to the use of thermo-mechanically treated (TMT) mild steel for the reinforcement. However, the long-term performance of RC structures is severely threatened by corrosion of embedded mild steel reinforcement, particularly in chloride-rich and carbonated environments. Corrosion undermines the protective alkalinity of concrete, initiating electrochemical reactions that generate expansive rust products, causing cracking, delamination, and spalling of cover concrete. Mechanically, corrosion reduces the cross-sectional area, ductility, and bond strength of reinforcement, while structurally it leads to diminished load-bearing capacity, serviceability issues, and in extreme cases, catastrophic collapse. Evidence from global case studies of bridges, parking garages, marine piers, and residential buildings illustrates the socio-economic cost of corrosion-related deterioration. This study synthesizes existing knowledge on corrosion mechanisms, their mechanical and structural implications, and highlights contemporary mitigation approaches. Strategies such as high-performance concretes, corrosion-resistant reinforcement, cathodic protection, coatings, and advanced monitoring technologies are discussed as means to enhance durability. The findings underscore the urgent need for durability-based design, proactive maintenance, and adoption of advanced materials, especially in developing regions where reliance on conventional mild steel persists. Ultimately, effective corrosion management is critical for ensuring safe, sustainable, and resilient infrastructure systems worldwide.