<p>This research focuses on the crucial parameter of foam concrete, its surface fractal dimension, which significantly influences mechanical and thermal characteristics. By correlating the fractal dimension D with thermal conductivity T, this study proves a robust relationship, confirmed through extensive analysis of measured thermal conductivity values from various literature.Moreover, by use of the physical foaming technique, foam concrete was produced from mostly cement and steel slag. The transient plane source technique was utilized to measure the thermal conductivity, from which the fractal dimension of the foam concrete was obtained.Consistent with that observed by the conventional SEM imaging technique, the fractal dimension dropped first and subsequently rose with the increasing steel slag content. Unlike conventional methods involving concrete slicing and sampling, our non-destructive approach relies on thermal conductivity measurement, offering simplicity, ease of operation, and preservation of concrete integrity. This innovative method presents a practical alternative for accurately determining the surface fractal dimension of foam concrete, enhancing efficiency, and minimizing structural damage.</p>