The Use of Municipal Solid Waste Incinerator Ash to Stabilize Dune Sands

Dune sands are problematic soils because they have low shear strength and are susceptible to collapse upon wetting. Dosages of municipal solid waste incinerator ash between 10 and 80 % were used to improve the engineering properties of dune sands. The soil-ash mixtures were allowed to cure for periods from 7 to 90 days. Laboratory tests such as compaction, unconfined compression, shear box and hydraulic conductivity tests were performed to measure the engineering characteristics of the stabilized material. The results showed that the maximum dry density remains approximately constant up to ash content of 30 % and then it decreases with the increase in ash content. The optimum water content increases with the increase in ash content. The unconfined compressive strength substantially increases with ash content up to 30 % and then decreases with the increase in ash content. The angle of friction follows similar trend to the unconfined compressive strength. However, the cohesion shows a steady increase with the ash content. The hydraulic conductivity of the stabilized material consistently decreases with the increase in the ash content. The effect of curing time on the hydraulic conductivity is minimal after 7 days of curing time. However, the unconfined compressive strength and the cohesion slightly increased with curing time up to 90 days.