The bridges are located at Palliodaivayal, Marudangavayal, Vallikkollaikadu, Maravanvayal, Manamelkudi, Kottaipattinam, Periyamadaippaychchal, Nattanipurasakudi, Kanatangudi, A Manakudi and Chitturuvadi. Structural audits conducted by a private consultancy for NHAI’s Ramanathapuram Project Implementation Unit identified damage to concrete and reinforcement at several locations.
The inspections included non-destructive tests such as Ultrasonic Pulse Velocity, Rebound Hammer and Half-Cell Potential tests. Low or doubtful ultrasonic pulse velocity readings indicated possible internal cracks, voids and deterioration of concrete, while Half-Cell Potential tests pointed to a high probability of reinforcement corrosion at several locations. Chemical tests also detected carbonation of concrete.
Physical inspections revealed exposed and corroded reinforcement, loss of steel cross-section due to rusting, cracked and debonded concrete cover, and spalling. Bearings at some bridges were found to be corroded and seized. Expansion joints at several locations were clogged with debris and vegetation, affecting drainage and contributing to water seepage, efflorescence and salt deposits on structural components. Cracks and localised damage were also observed in concrete railings and other elements.
Based on the findings, NHAI has floated a tender for repair, rehabilitation and structural strengthening. The proposed works include removing deteriorated concrete, treating and strengthening corroded reinforcement, pressure-grouting cracks, concrete jacketing of piers and other structural components, and applying carbon fibre-reinforced polymer (CFRP) to strengthen vulnerable members.
The consultants have recommended temporary structural propping before major repairs begin, particularly during the removal of damaged concrete from load-bearing components. Static deflection load testing has also been recommended after completion of the rehabilitation works, before the bridges are cleared for heavy traffic.
