EFFECT OF FINES CONTENT ON THE ENGINEERING PROPERTIES OF RECONSTITUTED LATERITIC SOILS IN WASTE CONTAINMENT APPLICATION

Abstract

A lateritic soil reddish brown in colour was reconstituted with inclusion of fines content in 0, 20, 40, 60, 80 and 90% to form six (6) different soil mixes (S1, S2, S3, S4, S5 and S6, respectively).   These soils were analysed to determine the effect of fines content on their engineering properties. Tests were carried out to determine index properties, compaction characteristics, strength properties (unconfined compressive strength (UCS) and undrained shear strength parameters) and hydraulic properties of the reconstituted soils. Specimens used for the determination of UCS, undrained shear strength parameters and hydraulic properties were prepared at the optimum moisture content (OMC) and compacted using the British Standard light, BSL (standard Proctor) energy.  Reconstitution of the natural soil (0% fines content) yielded soil samples having fines content between 61 and 93%, and grading modulus that decreased with higher fines content.  The specific gravity of the reconstituted soils decreased, while the Atterberg limits as well as derived plasticity parameters increased with higher fines content. The maximum dry density (MDD) and OMC decreased and increased, respectively, with higher fines content. The UCS and angle of shearing resistance generally decreased while cohesion increased with increase in fines content. The hydraulic properties improved with higher fines content. Test results indicate that the reconstituted lateritic soil samples meet the relevant requirements for materials to be used as hydraulic barrier in waste containment structures.