Calcined shale as low cost supplementary cementitious material

Abstract

Despite the various benefits of using metakaolin as a supplementary cementitious material (SCM), the high price of metakaolin limits its use in concrete to premium applications. However there are other sedimentary minerals, such as calcined shale, that may be able to fill the need for low cost, abundant SCMs in concrete construction. The study presented here investigated a low cost calcined shale, sourced from a lightweight aggregate producer, and compared its performance as an SCM to that of a commercially available metakaolin. The effect of both SCMs on compressive strength, resistance to alkali silica reaction and mixture workability were evaluated. Results show that, other than early age compressive strength, the performance of calcined shale in cementitious mixtures is comparable to that of metakaolin. Differences in behavior of the SCMs are discussed in the context of their chemical and physical properties.