NDT-Based Condition Assessment and Structural Safety Evaluation of a Reinforced Cement Concrete Water Tank in a Coastal Region: A Case Study

Reinforced cement concrete (RCC) water tanks are essential for water storage and distribution facilities in every region. The durability and structural integrity of RCC water tanks are crucial to maintaining an uninterrupted water supply to the surrounding areas. This study evaluates the structural integrity and functionality of a water tank in Karaikal, a coastal region in the Union Territory of Puducherry, India, subject to severe exposure conditions characterized by high humidity and temperature variability. An RCC water tank with a capacity of 10 lakh L in Thirunallar, Karaikal, is considered in this study. The methodology for the condition assessment includes visual inspection, non-destructive testing (NDT), and structural analysis in STAAD PRO software. NDT, including the Schmidt rebound hammer test and ultrasonic pulse velocity (UPV) test, was employed to evaluate the indicative compressive strength and in situ quality of an RCC water tank. The structure was modelled using structural drawings obtained from the Public Works Department, Karaikal. The NDT testing findings were incorporated into the model, and the structure was analyzed. Finally, the induced stress from the STAAD Pro model was compared with the in situ concrete compressive strength to assess the tank’s structural safety. The rebound hammer test results indicate that the in situ compressive strength of the tank’s beams and columns ranges from 12 MPa to 43 MPa, and the STAAD Pro analysis shows induced stresses ranging from 2.42 to 10.59 MPa. The comparison shows that the structure has higher safety margins. Hence, the deterioration observed during the visual inspection was not due to a deficiency in structural strength but rather to durability issues caused by environmental distress. Finally, suitable repair and rehabilitation methods were recommended to mitigate the deterioration based upon NDT measurements and the outputs of the structural analysis.