Use of cement kiln dust in blended cement concretes

This paper reports results of a study conducted to evaluate certain mechanical properties and durability characteristics of blended cement concretes, such as silica fume, fly ash and blastfurnace slag, incorporating up to 15% cement kiln dust. The results indicate that the compressive strength of silica fume and fly ash cement concretes with up to 10% kiln dust was marginally less than that of type I cement concrete. The compressive strength of slag cement concrete incorporating kiln dust was lower than that of other blended and type I cement concretes. A significant increase in the drying shrinkage was noted in the blended cement concretes. The electrical resistivity of blended cement concretes was, however, generally more than that of type I cement concrete. It is recommended to use 5% silica fume plus 10% kiln dust or 10% fly ash plus 10% kiln dust as a replacement of type I cement. Such usage would lead to technical, economic, and environmental benefits in terms of a reduction in the quantity of cement and utilisation of waste industrial by-products. As the electrical resistivity of blended cement concretes incorporating kiln dust is more than that of type I cement without kiln dust, it is expected that the useful service-life of the former would be more than that of the latter. As the compressive strength of slag cement concretes, incorporating up to 10% kiln dust, is low, it may be used in low- strength applications. It should, however, be noted that blended cement concretes require good curing to minimise drying shrinkage cracks.