Cement kiln dust (CKD) is a fine, powdery material, portions of which contain some reactive calcium oxide, depending on the location within the dust collection system, the type of operation, the dust collection facility, and the type of fuel used. CKD consists of four major components: unreacted raw feed, partially calcined feed and clinker dust, free lime, and enriched salts of alkali sulfates, halides, and other volatile compounds.
CKD can be used with fly ash and ground granulated blast furnace slag up to 15% by mass of cementitious material and in ground granulated blast furnace slag cements up to 10% by mass of cementitious material (Detwiler et al., 1996).
The following advantages are realized resulting from the addition of CKD along with fly ash and blast furnace slag to portland cement:
CKD must be considered and evaluated on a plant-by-plant basis since it varies in composition with respect to plant. CKD, when used alone, may result in decreased workability, setting times, and strength due to high alkali content. When using CKD with high alkali content, fly ash or blast furnace slag should be incorporated to prevent alkali-silica reaction problems. As with all other alternative cementitious materials, trial mixtures are required to achieve the desired cementitious properties.