Volume 28, Issue 6 (November 2005)
Statistical Evaluation of the Hydraulic Conductivity of Compacted Lateritic Soil
This paper examines the variation of hydraulic conductivity of a compacted lateritic soil with molding water content, dry unit weight, and initial degree of saturation under as-compacted conditions. Trends in the hydraulic conductivity versus molding water content relationships are similar to those obtained for nonlateritic, temperate zone soils. Hydraulic conductivity generally decreased as dry unit weight and initial degree of saturation increased. However, for the same values of dry unit weight, specimens compacted on the wet side of optimum water content yielded lower hydraulic conductivities than those compacted on the dry side of optimum water content. For lateritic soil specimens compacted at about 2% or more on the wet side of optimum water content, hydraulic conductivities less than 1 × 10−7 cm/s can be achieved when the dry unit weight is greater than or equal to 16.3 kN/m3 and initial saturation is greater than or equal to 88%. Statistical analysis of the results obtained in this study show that relatively weak relationships exist between hydraulic conductivity and molding water content or dry unit weight. Stronger relationships are obtained when hydraulic conductivity is plotted against initial degree of saturation. It is shown that a more accurate prediction of hydraulic conductivity can be achieved when a multiple regression equation is used to relate degree of saturation and compaction energy to hydraulic conductivity. The British Standard heavy compactive effort offers a wider range of molding water contents within which soils can be compacted to yield low hydraulic conductivity. This range is, however, limited by consideration for long-term desiccation and shear strength.