Cement Kiln Dust (CKD): Characterisation and utilisation in cement and concrete

Cement kiln dust (CKD) is a by-product of the cement manufacturing process. Despite the fact that usually its composition is similar to partially calcined raw feed, the variability in raw materials, fuel, type of process, dust collection systems and product specifications influence both the physical and chemical characteristics resulting in a highly variable material. As a result, a thorough characterization of the material has not been completed and commercial use of CKD in industry and products has been limited. The relatively high alkaline content of CKD is the predominant factor preventing its recycling in cement manufacturing. One effective way to utilize CKD is to use it in the production of blended cements. However research has been sporadic regarding the applicability of CKD as such an activator in concrete. Past research of blended cements containing CKD as a partial replacement of cement and ground granulated blast-furnace slag and/or fly ash has produced results that are variable and contradictory. The chemical composition of the CKD used most likely had a direct impact on the results obtained. The objective of this paper is to provide a general overview of the research that has taken place into the CKD production, composition, and characterization and the keys to utilization of CKD in the cement and concrete industry.