Experimental campaign for the physical, mechanical and chemical characterisation of the Matam soil: application to the study of supports of the Balterdi Bridge

This article is a follow-up to the first in situ work that determined the soil lithology of Balterdi Village (Matam, Senegal). The second phase present of the study consists of a physical, mechanical and chemical characterisation of the same soil in the laboratory. The various samples taken from the core drilling operations were tested and analysed in the laboratory for their classifications and nomenclatures in accordance with standard NF P11-300. In addition to these geotechnical tests, chemical tests (pH, sulphate ions, magnesium ions, chloride ions, salinity) were carried out on the soil and on the water table to determine their degree of aggressiveness and thus set the level of protection of the foundation concretes according to the NF P18-011 standard. Chemical analysis tests (pH, sulphate ions, magnesium ions, ammonium ions) were also carried out on some soil and river water samples in accordance with EN206-1. The various results of the laboratory tests have revealed three distinct soil horizons: brown to reddish clay, brown to reddish clay and beige silty to very silty sand. The results of chemical analyses reveal two classes of aggressiveness: a low environmental aggressiveness for reinforced concrete in civil engineering structures (XA1 class) and a: high aggressiveness due to chlorides present in water (XS3 class). It should be noted that the site in question is a tidal zone subject to an overflow of water from the river.