Study on the potential use of Tunisian clays as pozzolanic material

Samples of Tunisian clays from different locations are calcined at 600, 700 and 800 degrees C. Geotechnical, chemical and physical properties of both untreated and calcined samples are studied. The pozzolanic activity of the calcinated clays is evaluated by compressive strength performed on calcinated clay-calcium hydroxide mini-cylinders. The geotechnical study associated with the chemical analysis was found to be useful to predict the pozzolanic activity of the clays. Clays rich in kaolinite were shown to have the highest strength and therefore the best pozzolanic activity. The presence of some mineral clays such as illite, montmorillonite and muscovite does not improve the pozzolanic activity despite their relatively high level of silica, alumina and iron. (C) 2006 Elsevier B.V. All rights reserved.