PLASTICITY AND COMPACTION CHARACTERISTICS OF LATERITIC SOILS IN TOUNGO AREA, ADAMAWA STATE, NIGERIA

The plasticity and compaction characteristics of lateritic soils in Toungo area, Adamawa State, Nigeria were investigated to establish their suitability as civil engineering construction materials. Ten disturbed samples were subjected to geochemical and geotechnical analyses. The dominant oxides ranges are: silica (SiO2) (42.85 % to 45.34 %); aluminum oxide (Al2O3) (39.12 % to 39.20%); and iron-III-oxide (Fe2O3) (6.73 % to 8.96 %). The percentage fines, specific gravity SG and natural moisture content NMC ranges are (1.23% - 45.36 %), (2.57 - 2.64) and (11.65 % - 29.12 %) respectively. Samples TNG8 and TNG10 recorded more fines and higher NMC due to higher void ratio and clay in their void spaces. The liquid limits LL, plastic limits PL and plasticity index PI ranges are (17.25 % - 48.75 %), (13.15 % - 27.85 %) and (4.10 % - 20.90%) respectively. The ranges of maximum dry density MDD and optimum moisture content OMC are (2.830 g/cm3 - 4.15 g/cm3) and (6.15 % - 14.15 %) respectively. The soils are generally poorly graded and sandy clay with plastic fines. All the lateritic soil samples (except TNG8 and TNG10) are suitable as fill materials; only samples TNG4, TNG5 and TNG9 are suitable as base and sub-base materials; samples TNG1, TNG2, TNG3, TNG6 and TNG7 can be regarded as fair; while samples TNG8 and TNG10 can only be used after stabilization.