Influence of the origin of metakaolin on pozzolanic reactivity of mortars

Cement is one of the main sources of environmental impacts of concrete use. It is thus recognized that the most pragmatic solution for minimizing environmental impacts of concrete is the reduction of the cement content. This could be achieved by replacing a part of cement with mineral additions such as fly ash, blast-furnace slag or metakaolin (IVIK) during concrete mixing. In recent years, the incorporation of MK in building materials is growing. Metakaolin (Al(2)Si2O(2)) is a material obtained by calcination of kaolinite between 500 degrees C and 800 degrees C. In this study, Three MK issued from three different regions in Algeria were tested. The regions are, Jijel, Gulema and Bechar. This study aims to investigate the effects of the origin of MK blended at early age. The chemical and minalorgiques analysis (XRD, BET, SSB and SEM) show a difference in their metakaolinite content. One mortar prepared with 15% substitution rates of cement with different MK. The early-age reactivity of metakaolin-blended cement mortar was investigated. Isothermal calorimetry and compressive strength tests were performed. The hydration rate and the evolution of Ca(OH)(2) content of mortars were monitored using thermogravimetric analysis (ATG). The early age reactivity of the three MKs is very different. (C) 2017 The Authors. Published by Elsevier Ltd.