The possibility of improving the geotechnical properties of lateritic soils developed over migmatite gneiss by compacting it with lateritic soils developed over schistose quartzite was investigated. Petrographic analysis of the representative rock samples was carried out. Laboratory tests were executed in accordance with the specifications of British Standard 1337. Samples of the migmatite gneiss derived soil were thus mixed prior to compaction, with 10%, 20%, 30%, 40% and 50% of the soil

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... d from the schistose quartzite. The major minerals in the migmatite gneiss were quartz, alkali feldspar, plagioclase feldspar, biotite and muscovite while the schistose quartzite consists mainly of quartz and muscovite. Mechanical stabilization of the migmatite gneiss-derived lateritic soil with soil developed over schistose quartzite was quite effective. For instance, correlations coefficients of-0.75, 0.88 and 0.97 were established between the percentage of the stabilizer and optimum moisture content (OMC), unsoaked California Bearing Ratio (CBR) and cured Unconfined Compressive Strength (UCS) res0pectively. Significant decrease in the values of OMC and increase in the values of Maximum Dry Density, UCS and CBR were obtained upon stabilization with 40% of the stabilizer. Since marginal increases in CBR and UCS were recorded when the amounts of stabilizer were increased above 40%, this percentage is quite appropriate for the stabilization of the studied soil.