Study on the Improvement of Gravelly Laterites Using Mining Waste: Case of Phosphogypsum of Senegal

The objective of this study is to contribute to the valorisation of Senegalese phosphogypsum in road construction with the aim of improving the characteristics of lateritic gravel. Samples of laterite were taken in Ngoundiane and Tassette and physical and mechanical identification tests were carried out. An initial study on phosphogypsum and laterites was carried out, followed by the preparation of mixtures containing between 0 and 40% phosphogypsum with laterite. The results showed that phosphogypsum alone is not suitable for use as a base course. However, an optimal mixture of 30 % increases the fine content, reduces plasticity, and increases the CBR and compressive and tensile strengths. Nevertheless, phosphogypsum appears to be a granular corrector and allows for the judicious use of Tassette and Ngoundiane laterites as a base course. Keywords: phosphogypsum, recovery, road engineering, laterite