Viability of using calcined clays, from industrial by-products, as pozzolans of high reactivity

The present work studies the use of clays like high reactivity metakaolin, as pozzolans for concrete. This study adopted two clay types: kaolinite and kaolin by-products from the paper industry. In this second clay, besides the possible technical advantages, the ecological benefit of the use of a by-product must be considered. Initially, the chemical and mineralogical characteristics of the clays were determined. After this, calcination and milling was carried out aiming at obtaining materials with pozzolanic activity. After milling took place in the clays kaolinite and in the by-products, with the best physical characteristics, lab tests were carried out to verify the pozzolanic activity of these materials with Portland cement and with lime. The results show a low performance of the kaolinite and a high performance of the by-products industrial. The low performance of the kaolinite was credited to the lack of homogeneity of the calcination, as the material was obtained after the calcination, and the low efficiency of its milling process. (c) 2005 Elsevier Ltd. All rights reserved.