Manufactured aggregate from cement kiln dust

Abstract

This paper presents the results of a laboratory study that evaluated the geotechnical and geoenvironmental properties of a manufactured aggregate derived from cement kiln dust (CKD). The aggregate manufacturing process involves accelerated carbonation technology (ACT), has been used to treat contaminated soils at trial scale. The process operates at commercial scale in the UK, producing aggregates from thermal residues. The ACT process relies on the accelerated reaction of carbon dioxide with the calcium oxide in the CKD material in the presence of water. No additional binder was used in this study, relying solely instead on the formation of carbonate to form the aggregate. In this paper, the aggregate manufacturing process is briefly described. To explore future potential construction applications of the aggregate, several geotechnical test results are used to assess strength and durability (i.e. individual particle strength, internal shear strength of the particle assemblage, wet–dry testing, freeze–thaw testing). Screening tests on the aggregate’s geoenvironmental characteristics are discussed (metal leaching, dissolved heavy metal adsorption and hydraulic conductivity) to assess potential uses further. It is shown that the aggregate studied has adequate properties for a variety of construction applications, but is unsuitable for use in freezing and thawing environments.