Design of Compacted Lateritic Soil Liners and Covers

Laboratory tests were conducted on three lateritic soil samples to illustrate some pertinent considerations in the design of compacted lateritic soil liners and covers. The three design parameters investigated are hydraulic conductivity, desiccation-induced volumetric shrinkage, and unconfined compressive strength. Test specimens were compacted at various molding water contents using four compactive efforts. The compaction conditions were shown to have some relationship with soil compaction using either the plasticity modulus or the plasticity product (i.e., clay index). For construction quality assurance purposes, the traditional approach was compared with the modern criterion. Deficiencies associated with the traditional approach for soil liners found in literature also apply to lateritic soils. Overall acceptable zones were constructed on the compaction plane to meet design objectives for hydraulic conductivity, volumetric shrinkage strains, and unconfined compressive strength. The line of optimums was identified as a suitable lower bound for overall acceptable zones of lateritic soils. The volumetric shrinkage strain was also identified as the second most important design parameter for lateritic soils. The shapes of the acceptable zones were affected by the fines contents of the soils.