Influence of Compactive Efforts on Compacted Foundry Sand Treated With Cement Kiln Dust

Laboratory tests were carried out on foundry sand treated with up to 12% cement kiln dust (CKD) by dry weight of soil to determine its suitability for use as road pavement material. Specimens were compacted at the energy levels of Standard Proctor (BSL), West African standard (WAS) and British standard heavy (BSH). The foundry sand utilized in this study is classified as A-2(0) or SM using the America Association of Highway and Transportation Officials (AASHTO) and the Unified Soil Classification System (USCS), respectively. The 7day unconfined compressive strength (UCS) values recorded for the natural soil at BSL, WAS and BSH compactive efforts record values of 165, 316 and 344 kN/m2 respectively, while peak values of 416, 378 and 444 kN/m2 were recorded at 8 % CKD, 6 % CKD and 6 % CKD treatments of foundry sand, respectively. None of the Specimens attained the UCS value of 1710 kN/m2 conventionally used as criterion for adequate cement stabilization. California bearing ratio values recorded for the untreated foundry sand at BSL, WAS and BSH compactive efforts are 4, 6 and 8%, respectively. While peak California bearing ratio values of 15, 20 and 52% were recorded at 12% CKD treatments for BSL, WAS and BSH compactive effort respectively. The CBR values of 20 and 52% at treatment level of 8% CKD for WAS and BSH compactive effort satisfy the recommended minimum CBR value of 20-30% when compacted at optimum moisture content and 100% West African standards for sub-base material. The durability of specimens determined by immersion in water failed to produce an acceptable loss in strength value of less than 20% as specified for tropical soils. Keywords: Cement Kiln Dust, Compacted Durability, California bearing ratio, Unconfined Compressive strength