Study on Compressive Strength of Concrete Subjected to Sustained Elevated Temperature with different Grades of Concrete

Concrete structures often face challenges under elevated temperatures, which can compromise their mechanical properties and durability. Understanding the behaviour of different concrete grades under such conditions is crucial for ensuring their performance in high-temperature environments. This study investigates the thermal behaviour and mechanical performance of concrete grades M20 and M30 under sustained elevated temperatures. Experimental trials examined compressive strength, mass loss, and visual changes in specimens subjected to temperatures of 250°C, 275°C, and 300°C for two hours. Results reveal distinct trends in weight loss and compressive strength across temperature intervals. M20 grade concrete exhibited higher vulnerability, with a pronounced reduction in strength and weight compared to M30. M30 grade concrete displayed superior thermal resistance, attributed to its enhanced mix design. Both grades showed comparable degradation patterns at higher temperatures, with an overall compressive strength reduction of approximately 35%. Visual observations highlighted discoloration, microcracks, and chalky textures as indicators of thermal stress. The findings underscore the significant influence of material composition on concrete's thermal performance, emphasizing the importance of selecting appropriate grades for high-temperature applications.