Evaluation of the optimal process of thermal activation of kaolins

Metakaolin is a pozzolanic material obtained through thermal activation of kaolin. this researchaims to investigate the effect of degree and duration of heating on the pozzolanic properties and reactivityof the produced material. two types of iranian mineral raw material, namely, k1 and k3, and one byproductof the domestic kaolin beneficiation process, k2, were activated by heating in a furnace chamberat temperatures 650–900 °c for 1 and 2 h. the changes in the crystalline structure of these materialswere evaluated using x-ray diffraction (xrd), and also compressive strength tests were carried out onthe mortars containing metakaolin to study the reactivity of the produced materials. the obtained resultsindicated that 1 h is sufficient for thermal activation of kaolin, and the optimal activation temperature isbetween 750 and 850 °c. moreover, it was observed that activated metakaolin has an appreciable influenceon the increase in compressive strength of the mortars