STRENGTHENING OF THE ROADBED LAYER OF THE RN4

The RN4 is one of the major routes in Burkina Faso that connects the capital and largest city of the country, Ouagadougou, to the eastern cities such as Koupela. Within Ouagadougou, the urban section of this national road passes through Komber-Pandema Avenue at the East interchange and traverses wetlands that border the lakes and ponds of the city. As part of the rehabilitation of this wet stretch, the company COGEB International aimed to strengthen the roadbed foundation layer to cope with potential hydraulic pressures and the wet-dry cycles associated with the rainy and dry seasons.

Initially, a granular drain mat was installed at the PST (Upper Part of Earthworks) level to capture flows and percolations from surrounding water basins that could potentially reach beneath the road structure. For the reinforcement of the road structure, the Macgrid® EG geogrid was installed sandwiched between the drain mat and the foundation layer. The MacGrid® EG geogrids are polypropylene geogrids manufactured using an extrusion process characterized by symmetrical strength in both directions. The extruded structure of this geogrid allows for better distribution of forces within the road layers, reducing the stresses applied to the foundation soil, thereby reinforcing the road structure. It also increases the bearing capacity of the unbound layers due to its stiffness combined with its bidirectional tensile strength.