TAKING INTO ACCOUNT THE SWELLING AND SHRINKAGE OF EXPANSIVE SOILS IN THE DESIGN AND BEHAVIOR OF PAVEMENTS

This work focused on the influence of swelling-shrinkage cycles on expansive soils and the behavior of pavements built on these soils in the Lama Depression, specifically on the Sehoue-Massi section of National Interstate Route No. 2 in southern Benin, a vital artery linking the north and south of the country. Its main objective was to study the variation in bearing capacity (CBR index) of swelling clay soils subjected to repeated swelling-shrinkage cycles, in order to improve pavement design and anticipate their behavior in the face of this phenomenon. After a literature review on the phenomenon and the pathologies observed on affected roads, soil samples were collected for analysis. The soil analysis revealed that it was a non-organic, swelling clay soil with a high susceptibility to swelling and shrinkage. The study, conducted over eight wetting-drying cycles, resulted in a 5% to 8% increase in CBR bearing capacity, representing a 60% improvement. However, these values remain low, and the studied expansive clay is still classified as S3. The pavement design, carried out according to the specifications of the Algerian CTTP 2001 catalog, favored a flexible structure adapted to the low bearing capacity of the soil.