Enhancing the post-fire behavior of steel slag normal-strength concrete by adding SCM

Abstract

Tests were conducted on 360 specimens to investigate the post-fire behavior of slag concrete containing supplementary cementitious material (SCM) consisting of fly ash (FA) or silica fume (SF) upon exposure to 400, 600, 800 and 1000 °C. Eighteen concrete mixes with different contents of basic oxygen furnace slag coarse aggregate (BSSCA), FA and SF were prepared. The physical post-fire behavior was assessed by heating curve, weight loss, surface change and residual compressive strength while the chemical composition change was investigated by X-ray diffraction analysis. Results revealed that the residual strength of concrete containing BSSCA, with or without FA or SF, was better than that of natural aggregate concrete. This study successfully verifies that using BSSCA in concrete mix design will improve the post-fire residual strength. Further, no detrimental effect on the residual strength when partial cement was replaced by FA/SF to lower the carbon footprint. Accordingly, the combined use of BSSCA and SCM could produce more sustainable and robust concrete after exposed to elevated temperature.