The metakaolin was produced by thermal treatment (calcination) of the starting high-
-quality kaolin clay from Serbia. The optimal calcination parameters, for which nearly
complete dehydroxylation of the material was achieved, are: temperature 650 °C and
heating time of 90 min. The conversion of the kaolinite to metakaolinite was confirmed
by XRD and IR analyses of the starting and thermally treated kaolin samples. The pozzolanic
activity was determined by Chapelle test. The obtained value 0.65 g Ca(OH)2/g
of metakaolin indicates that produced metakaolin may be used as supplementary cementitious
material