Potential of low-grade kaolinitic clay as a cement substitution in concrete

Metakaolin, produced from pure kaolinitic clays have been used as a supplementary cementitious material over the years due to its technical benefits. However, the availability of pure kaolinitic clays remain a challenge since it can be found in only specific areas. This work, therefore, investigates the potential use of less pure kaolinitic clays, which is found almost everywhere as SCM for construction purposes. XRF, XRD and TG/DSC analysis were conducted on the clay. The clay was calcined at 600 oC and used to partially replace ordinary Portland cement by 10 wt%, 20 wt% and 30 wt%. Compressive strength was found to decrease as calcined clay content increased.