Analysis of mechanical and physical behaviour of post-burn concrete

Abstract

The occurrence of a high temperature change, such as in a fire incident will have an impact on the concrete structure, cracked surface structure, damage/collapse, and discoloration of the concrete. This research is conducted on K300 concrete with a sample of 15 cm x 15 cm x 15 cm cubes. Burning is carried out at temperatures of 250°C, 500°C, 750°C, and 1000°C with a containment time of 2, 4 and 6 hours. The cooling process is carried out by immersion then rested for 24 hours at room temperature. From the results of the research obtained at temperatures of 250°C, 500°C, 750°C, and 1000°C, the decrease in compressive strength are 4.44% -7.41%, 12.59% -22.96%, 56.44% -66.22%, and 76.74% - 100%. At the containment time for 2 hours, 4 hours and 6 hours, the decrease in compressive strength are w = 4.44% - 76.74%, 6.67% -93.70%, and 7.41% - 100%. At temperatures of 250 °C, 500°C, 750°C, and 1000°C, the increase in porosity are 8.09% - 9.57%, 11.79% - 15.50%, 16.98% - 18.46%, and 19.20% - 26.61%. At the containment time for 2 hours, 4 hours, and 6 hours, the increase in porosity are 8.09% - 19.20%, 8.83% - 22.16%, and 9.57% - 26.61%. From this research, it can be seen that the increase in temperature has a greater impact on the decrease in the compressive strength of concrete and the increase in the porosity of concrete compared to the increase in the combustion duration. Through this research, regression equations are generated which can be used to calculate the residual compressive strength at other combustion temperatures.