STRENGTH CHARACTERISTICS OF LATERITIC SOIL- ROCK FLOUR MIXTURES STABILISED WITH LIME FOR ROAD PAVEMENT APPLICATION

Abstract

The study evaluated the strength characteristics of lateritic soil-rock flour mixtures stabilized with 0,3,6,9 and 12% soil- rock flour ratio with lime ratio of 0, 2.5, 5,7.5 and 9%, compacted at optimum moisture content (OMC) using British Standard Light (BSL), West Africa Standard (WAS) and British Standard Heavy (BSH) compactive efforts. Results showed that the lateritic soil sample used for this study is classified as A-7-6 according to American Association of State Highway and Transportation Officials (AASHTO). The formulated mixtures from the A-7-6 soil and rock flour with lime showed an improvement in the index properties of the stabilized soil. The results showed a decrease in Liquid limits, Plastic limits and plasticity index respectively with increase in rock flour and lime content. The results also showed a slight decrease in maximum dry density (MDD) and increased optimum moisture content (OMC). Addition of rock flour and lime to the natural soil shows improvement in the CBR and Durability values of the stabilized specimen. BSH gave the highest value of 38.97% at 12% RF and 10% lime for CBR, while BSH gave the highest value of 855.94 kN/m2 at 12% RF and 10% lime for durability. Furthermore, the unconfined compressive strength (UCS) of the sample were greatly improved with the addition of rock flour and lime at various compaction energies, The results showed that the unconfined compressive strength increased with increasing lime and rock flour content from 132.57 kN/m2 at 0 % to 497.53 kN/m2 for 12% rock flour and 10% lime content when compacted with British Standard light compaction effort, 850.04 kN/m2 at 0 % to 1,176.62 kN/m2 for 12% rock flour and 10% lime content for West Africa Standard compaction effort and 740.27 kN/m2 for 0 % to 1,129.56 kN/m2 for 12% rock flour and 10% at British standard heavy compaction effort. This therefore indicates overall, that the addition of rock flour and lime (12%RF and 10% lime) to poor/weak lateritic soil improved the soil strength and resistance to loss in strength. This study has established the potentials of using rock flour and lime to stabilize a class of lateritic soil for pavement construction purposes.