PROPERTIES AND CHARACTERISTICS OF LIME TREATED LATERITE SOILS .

Abstract

The construction of rural and low traffic roads to meet the present day and future requirements is the greatest challenge for transportation engineers in the developing countries. The greatest handicap for the construction of good road network and the improvement of village roads is the scarcity of suitable local construction materials coupled with inadequate funds. Construction cost can be reduced through stabilization. One of the methods is by lime treatment. In this study, the influence of the physical characteristics of five selected laterite samples on their engineering behaviour in the natural untreated state and on their responsiveness to treatment with lime as chemical stabilizing agent was determined in the laboratory. The percentages of lime used on the laterite samples varied from 2% to 10%. Tests on both the cured and uncured mixture produced increase in CBR val ue, unconfined compressive strength, compressive strength, shear strength and failure stress with increasing lime content. The rate of increase depends on the soil type. The optimum moisture content. the plastic limit and the liquid limit of the mixture increase with increasing lime content while the maximum dry density, plasticity index, ultimate strain, linear shrinkage and swell decrease with increasing lime content. Beneficial results were obtained using lime additive for treating all the samples especially the highly plastic and organic, soil types such as sample type A. 'which in its untreated condition can be often detrimental for use as subbase material for road construction as a result of differential expansion and shrinkage when it undergoes changes in moisture

content. Lime treatment of the soil sample reduces the change in volume when it undergoes changes in moisture content and improves strength characteristics which make the treated soil suitable for use as subbase material. The increase in strength of treated soil samples C and D make them suitable for use as base material. The results also show that the minimum lime content for treatment of the tested lateritic soils for use as either subbase or base material in pavement construction is 6%.