Calcined clayey soils as a potential replacement for cement in developing countries

Influence of alkali activator type and proportion on strength performance of calcined clay geopolymer mortar

“…But, competing demand by different industries for high purity kaolin clay, high cost and intensive purification process are some of the factors limiting its availability to be used as either SCM or precursor for alkali activation [6]. Calcined clays are presently considered as cost-effective alternatives to high purity metakaolin clay and offer greater supply sustainability, due to the availability of vast clay reserves globally supplemented by clay waste generated by the ceramics industries and from construction projects [7]. Many of these clays have high iron contents and used to be considered unsuitable precursors for geopolymers [8], until recently, when research proved the viability of red geopolymer cement [9].…”