Fractal Dimension of Steel Slag Foamed Concrete and Its Connection with Compressive Strength

Abstract This study utilized physical foaming to prepare steel slag foamed concrete (SSFC) using steel slag (SS) and cement as the primary raw materials. The compressive strength and microstructure of SSFC with different SS substitutions were tested, and the changes in pore size distribution and fractal dimensions were investigated, along with their relationship to the strength of SSFC. The pore size distribution of SSFC conforms to a log-normal distribution, and its pore structure exhibits distinct fractal characteristics. With increasing SS proportion, both the average pore size and fractal dimension of SSFC initially decrease and then increase, reaching their minimum values when the SS proportion is 20%, at which point the pore structure is most uniform. However, the compressive strength exhibits a clear inverse correlation, peaking at a SS proportion of 20%. The analysis indicates that a smaller fractal dimension corresponds to a more uniform pore structure and denser matrix. A numerical connection between the strength of foamed concrete and the fractal dimension has been further established, theoretically elucidating the trend that strength decreases with an increase in fractal dimension, which is consistent with the macroscopic experimental results.