COMPACTION BEHAVIOUR OF PERIWINKLE SHELL ASH TREATED LATERITIC SOIL FOR USE AS ROAD SUB-BASE CONSTRUCTION MATERIAL

Lateritic soil treated with up to 12% periwinkle shell ash (PSA) by dry weight of soil was evaluated for use as road pavement material. Three compaction energies were used: British Standard light (BSL), West African Standard (WAS) and British Standard Heavy (BSH). The maximum dry density increased with decrease in optimum moisture content for all compaction efforts. Peak unconfined compression strength (UCS) and California bearing ratio (CBR) were obtained at a threshold of 6% PSA content for all compaction efforts. Durability assessment showed that the resistance to loss in strength increased with increase in PSA content but did not show any consistent trend with increasing compaction effort. Peak resistance to loss in strength of 24.3% was obtained at 8% PSA treatment for British standard heavy compaction effort. Microanalysis studies revealed that improvement in soil properties was due to the formation of cementitious products of calcium silicate hydrate and calcium aluminate hydrate at inter particle contact of soil grains. The study showed that PSA can be used to improve lateritic sub-base of lightly trafficked roads, but would be more effective as admixture in either lime or cement stabilization of lateritic soil. © 2019 Taiwan Geotechnical Society.