Hydraulic concrete is one of the most important materials in construction. The optimum composition will give us a quality hydraulic concrete, which is recommended in the field of civil engineering, and to obtain a desired hydraulic concrete based on the quality and dosage of the constituents for a mix, this study was to evaluate the importance of geotechnical studies in the manufacture of hydraulic concrete during the construction of structures in Bukavu. The Dreux-Gorisse method of concrete formulation was applied to the construction sites.