In addition, the usage of marble dust as a partial replacement of sand showed an improvement in porosity values. This improvement in porosity could be explained as a result to the filler effect of marble dust. The filler effect of marble dust was proved by Kristulovic [14] and Demirel [12].
The relationship between compressive strength (fc) and porosity (P) of the series at 56 days is shown in Fig. 25. The best fits of results obtained in the study are presented respectively for concrete with marble dust as partially replaced cement and partially replaced sand as follows in Eqs. (7) and (8):