Hydraulic Conductivity of Compacted Tropical Clay Treated with Rice Husk Ash

Abstract

Laboratory study on compacted tropical clay treated with up to 16% rice husk ash (RHA), an agro-industrial waste; to evaluate its hydraulic properties and hence its suitability in waste containment systems was carried out. Soil-RHA mixtures were compacted using standard Proctor, West African Standard and modified Proctor efforts at-2, 0, 2 and 4% of optimum moisture content (OMC). Compacted samples were permeated and the hydraulic behaviour of the material was examined considering the effects of moulding water content, water content relative to optimum, dry density and RHA contents. Results showed decreasing hydraulic conductivity with increasing moulding water content and compactive efforts; it also varied greatly between the dry and wet side of optimum decreasing towards the wet side. Hydraulic conductivity generally decreased with increased dry density for all effort. Hydraulic conductivity increased with rice husk ash treatment at the OMC; but were within recommended values of 1 x 10-7 cm/s for up to 8% rice husk ash treatment irrespective of the compactive effort used. This shows the suitability of the material as a hydraulic barrier in waste containment systems for up to 8% rice husk ash treatment and beneficial reuse of this agro-industrial waste product.