Combined Effects of Bottom Ash and Lime on Behaviour of Expansive Soil

Abstract

This study illustrates the effectiveness of combining bottom ash and hydrated lime to enhance the engineering properties of expansive soil. The bottom ash was collected from Eraring Power Station in New South Wales, Australia, as a by-product of coal-fired power stations, and soil specimens were used as artificial soil including kaolinite, bentonite and fine sand in a reasonable ratio to stimulate soil samples with characteristics of expansive soil. The stabilised soil samples were prepared by altering the bottom ash content from 0% to 30% on a dry weight basis of expansive soil as well as with constant percentage of 5% in hydrated lime. Through conducting a series of experimental tests including linear shrinkage and unconfined compressive strength (UCS) in various curing time, the shrinkage and strength behaviour of treated soils were investigated and compared with untreated soil samples. The results revealed that the combination of bottom ash and hydrated lime significantly reduced the linear shrinkage, while it increased the strength of expansive soil. The use of bottom ash alone is not recommended due to a slight increase of linear shrinkage and a minor negative impact on the soil strength. The optimum content of combined bottom ash and hydrated lime to stabilise expansive soils is also presented.