Pavement infrastructure built on expansive soil can experience multiple forms of degradation, mainly cracks when there are no adequate arrangements made to avoid or to limit the impact of the changes on the volume of the supporting soil. In this research, three objectives have been adopted in-depth on the performance characteristics of West Africans soil and aim to (i) accessing characteristics of soil types in the region; (ii) assessing the performance of these soils with 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5% and 5.5% of cement and (iii) using geogrid to evaluate the performance of pavement on clayey soil. Design of flexible pavement is largely based on empirical methods using layered elastic and two-dimensional finite element (FE) analysis. Currently a shift underway towards more mechanistic design techniques to minimize the limitations in determining stress, strain and displacement in pavement analysis. For this reason, computational analysis of pavement methods have been investigated on the structural model pavement and the effectiveness of geogrids as a reinforcement of layer in a flexible pavement system. In this study, flexible pavement modeling is done using Abaqus software in which model dimensions, element types and meshing strategies are taken by successive trial and error to achieve desired accuracy and convergence of the research. Flexible pavements (with and without geogrids) were built and subjected to 127.49 kN load applications and the Finite Element Method (FEM) as computer analysis under static load. The results reveal that the proportion of percentage cement leading to the best performances varying from 3% to 5.5%. And, the pavement made with geogrid in subgrade is the best. As a conclusion, in an unstable area, this research suggests the use of silty clayey sandy treated with a minimum percentage of 3% cement in subbase layer and geogrid in subgrade because, the inclusion of geogrid in subgrade reduces the deformation.