Abstract
The fire safety of concrete structures is a major concern, as exposure to severe thermal environments causes significant degradation of the material’s mechanical properties and integrity. This study aims to evaluate the impact of high temperatures on concrete in order to identify critical degradation thresholds and analyze the associated physicochemical mechanisms. A concrete mix was prepared using cement and local aggregates to achieve an average concrete strength of three distinct test groups with an overall mean initial compressive strength of 41.8 MPa. Concrete cores were subjected to temperature stages set at 200°C, 400°C, 600°C and 800°C for periods of 60 and 120 minutes, followed by compressive strength tests and mass loss measurements. The results obtained reveal a slight decrease in the characteristics of the concrete at temperatures below 400°C. Above this temperature, there is a drastic drop in the physical and mechanical performance of concrete, particularly in terms of compressive strength. In fact, there is an almost exponential decrease in compressive strength, which drops from 41.8 MPa before firing to 8 MPa and 4.9 MPa for firing at 800 °C for 60 and 120 minutes. This thermal degradation is due to the decomposition of portlandite, which leads to a decline in density, increase in porosity and loss of bonds between aggregates, as well as the appearance of micro cracks in concrete test specimens.
Keywords: Compressive Strength, Concrete Performance, High Temperatures, Mass Loss, Thermal Degradation.