INTERNATIONAL JOURNAL FOR INNOVATIVE RESEARCH IN MULTIDISCIPLINARY FIELD

Abstract: Concrete is one of the most extensively used structural materials in the construction industry due to its versatility and adaptability for a wide range of applications. In India, most reinforced cement concrete (RCC) elements such as slabs, beams, and columns are commonly constructed using M30 grade concrete, which falls under normal strength concrete. During their service life, concrete structures may be subjected to various natural and man-made hazards, including earthquakes, floods, cyclones, and landslides. Among these, fire accidents represent one of the most critical threats, as they can expose structures to extremely high temperatures. Although concrete is generally considered a fire-resistant material, exposure to elevated temperatures can significantly alter its physical and mechanical properties. In severe fire incidents, temperatures may exceed 1000°C depending on the intensity and duration of exposure, leading to substantial structural damage.

To simulate fire exposure conditions, an experimental program was conducted to study the effect of elevated temperatures on concrete specimens. Cube specimens of size 150 mm × 150 mm × 150 mm were cast and subjected to temperatures ranging from ambient conditions up to 1000°C at increments of 150°C for a duration of three hours. The residual compressive strength of the concrete was then evaluated using both destructive testing and non-destructive techniques, including Rebound Hammer and Ultrasonic Pulse Velocity (UPV) tests. In addition to strength assessment, physical changes such as color variation, strain, crack width, and percentage of weight loss were carefully observed. Furthermore, the temperature distribution within the concrete specimens was measured by embedding thermocouples at intervals of 75 mm from the surface to the core, enabling the analysis of thermal gradients. The results obtained from destructive testing were compared and validated with non-destructive test outcomes to ensure reliability and consistency of the findings.