IMPROVING MARGINALLY SUB-STANDARD GRAVEL FOR SUB-BASE MATERIAL IN ROAD CONSTRUCTION: LESSONS FROM THE APOWA-KEJEBRIL ROAD

The successful performance of roads, to a large extent, depends on the pavement structure that is capable of carrying the imposed traffic loads. However, in some cases, the subgrade is too weak requiring removal and replacement with a stronger granular material. Material weaned from borrowed pits may be deficient in meeting the required standard parameters for use as road pavement layers. Chemical and/or mechanical stabilisations have been employed in improving the host material to meet the desired applicable engineering properties. This study investigates the impact of three proportions of cement (2, 4, and 6% by soil weight) on samples of gravel from borrowed pits used for reconstruction of the Apowa-Kejebril road, Western Region, Ghana.  The index properties of gravel samples (e.g. gradation, Atterberg limits, specific gravity and Los Angeles abrasion test), and the advanced characterisation of the cement-stabilised material through resilient modulus at different partial saturation conditions and compressive and tensile strengths were established. The results suggest that cement stabilisation at doses ranging between 2 and 6% by weight of soil efficiently improves the mechanical properties of the gravel materials from the burrow pits, allowing for their use for subbase material for the Apowa-Kebril road project, a flagship composite flexible road with all concrete block paving as the road surfacing material.