COMPARATIVE ANALYSES OF THE ENGINEERING PROPERTIES OF LATERITES DERIVED FROM DIFFERENT ROCK TYPES ALONG YOLA-MUBI FEDERAL HIGHWAY

This research investigated the qualities of laterites in localities along Yola-Mubi Federal Highway; to evaluate their suitability as civil engineering construction materials. The study area has tropical climate and the existing rocks are sandstones, basalts, older granites, gneisses and migmatites. Ten laterite samples from five different localities (VG1, VG2, GS1, GS2, MG1, MG2, MH1, MH2, BM1and BM2) were subjected to geotechnical investigations in accordance to BS1377 (1990). The particle size distribution ranged; gravel (0% - 18 %), sand (39% - 94 %,) and fines (5% - 61%). The highest LL of 43.15% was recorded on GS2 and VG2 has the highest PL of 25.15%. GS1 yielded highest PI of 36.46%. The highest NMC of 30.01% was recorded on GS1 while the lowest NMC of 8.75% was recorded on VG2. The mean SG (2.685) of the basaltic samples and the SG (2.57) on the sandstone samples differ significantly. The highest MDD of 1.84 mg/m3 was recorded on VG2 while MG1 yielded the lowest MDD of 1.50 mg/m3. The highest OMC of 18.75 % was recorded on VG2 and MG1 has the lowest OMC of 12.38 %. The highest UCS of 42 kPa was recorded on MG1 while BM2 recorded the lowest UCS of 27 kPa. The unsoaked CBR ranges from 55% to 86%; they are directly proportional to SG and MDD; and inversely proportional to the NMC, OMC and LL. Samples VG1, VG2, MG1, MG2, MH1 and MH2 satisfied the requirements (OMC, LL, PI and fines content) and are likely to be good as general fills, sub-base and embankment materials. All samples except VG1 and VG2 are poor as base course materials; their UCS and CBR fall outside specifications. Sandstone derived laterites (VG1 and VG2) are the most suitable for civil engineering construction purposes.