Experimental study on the use of crushed granite sand for lithostabilization of lateritic soils in road construction

The use of local materials in road infrastructure provides a sustainable alternative to the high costs of conventional construction materials. However, certain lateritic gravels exhibit insufficient geotechnical properties for direct use in pavement layers. This study evaluated the potential improvement in the physical and mechanical properties of two types of lateritic gravels through the incorporation of crushed granite sand. Four addition rates were investigated: 15%, 20%, 25%, and 30%. The laboratory tests included particle size analysis, Atterberg limits, sand equivalent, Modified Proctor compaction, and California Bearing Ratio (CBR) tests. The results showed that the addition of crushed granite sand significantly enhanced the gradation and dry density of the materials while reducing their plasticity. For the first lateritic gravel, a 20% addition of crushed granite sand yielded a CBR value of 14 and a plasticity index (PI) of 15.8%, making it suitable for use as a subgrade layer, according to CEBTP standards. The second lateritic gravel, improved with 15% crushed sand, achieved a CBR of 35 and a PI of 19.7%, meeting the requirements for a foundation layer. These findings highlight the effectiveness of lithostabilization with crushed granite sand as a sustainable approach to improve and valorize local lateritic materials for road construction.