Physical and Mechanical Features of the Quaternary Basanites of the Cap-Vert Peninsula of Dakar (Senegal, West Africa)

Abstract

This work presents the results of geotechnical tests carried out in the laboratory on specimens of Quaternary olivine basanites from the Cap-Vert peninsula of Dakar. The samples were taken following geotechnical investigations in the Fann-PE, Mermoz-Ouakam, Yoff and Ngor areas respectively. The results obtained show a dry density between 20.45 and 29.30 kN/m3 which corresponds to medium to high density basanites. The porosity varies between 0.33% and 4.20%. For microlitic basanites, the porosity remains low, on the other hand, for micrograined basanites; a slight increase in porosity is noticed. As for the methylene blue adsorption test value measured, it is between 0.25 and 1.10. The uniaxial compression strength (Rc) and Young’s modulus (E) vary respectively from 12.19 MPa to 41.748 MPa and from 1477.6 MPa to 7699.1 MPa. The low strength values are recorded in altered and vesicular basanites. Also, a correlation was made between uniaxial compression strength and porosity and showed a gradual decrease in strength with increasing porosity.