Abstract: To investigate the impact of equal volume replacement of coarse aggregate by industrial steel slag stone on the mechanical and durability properties of concrete, we produced 144 specimens with varying steel slag replacement ratio, water-cement ratio, and concrete strength grade to test the mechanical properties, frost resistance, and carbonation resistance of the specimens. The results indicate that the greater the steel slag replacement rate, the larger the difference in carbonization depth between the top surface and the bottom surface. G-0.45-100 (here 0.45 represents the water-cement ratio and 100 means that the replacemen ratio is 100%) exhibited the largest difference, at 53.4%. Moreover, steel slag concrete demonstrates better strength and frost resistance at the same age. At a steel slag replacement rate of 100%, the 28-day compressive strength of steel slag concrete with a water-cement ratio of 0.45 increased by 13% compared with that of ordinary concrete. The splitting tensile strength and the flexural strength increased by 12.6% and 7.1% respectively. SEM test revealed that the interface transition zone (ITZ) of steel slag and cement stone was denser than that of ordinary aggregate, less affected by freeze-thaw cycles, and exhibited superior interface bonding. Additionally, through multiple regression analysis and the least square method, we established a numerical model for compressive strength and a freeze-thaw damage model of steel slag coarse aggregate concrete with good fitting accuracy.

Key words: steel slag concrete, mechanical properties, freezing resistance, carbonation resistance, microscopic analysis, numerical model