HIGH-TEMPERATURE, RESISTANT, ARGILLITE-BASED, ALKALI-ACTIVATED MATERIALS WITH IMPROVED POST-THERMAL TREATMENT MECHANICAL
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HIGH-TEMPERATURE, RESISTANT, ARGILLITE-BASED, ALKALI-ACTIVATED MATERIALS WITH IMPROVED POST-THERMAL TREATMENT MECHANICAL STRENGTH TOHOUE MONIQUE TOGNONVI1, SVETLANA PETLITCKAIA2, AMENI GHARZOUNI2, MYRIAM FRICHETEAU2, NATHALIE TEXIER-MANDOKI3, XAVIER BOURBON3, AND SYLVIE ROSSIGNOL2 * 1
Unité de Formation et de Recherche des Sciences Biologiques, Université Peleforo Gon Coulibaly, BP 1328, Korhogo, Côte d’Ivoire 2 Institut de Recherche sur les Céramiques (IRCER), 12 rue Atlantis, 87068 Limoges Cedex, France 3 Agence Nationale pour la Gestion des Déchets Radioactifs, 1–7 rue Jean-Monnet, Parc de la Croix-Blanche, 92298 Châtenay-Malabry Cedex, France
Abstract—Fire resistance performance is one of the most important requirements in geological storage conditions in order to improve the resistance of storage packages to high thermal constraints (in the case of a fire for example). With the need to develop new fire-resistant materials, the aim of the present study was to develop fire-resistant geopolymer binders based on CallovoOxfordian (COx) argillite. Two types of kaolin with different degrees of purity were mixed with argillite in various proportions. These mixtures were calcined at 600 or 750°C. In order to assess the fire resistance of activated materials, thermal treatment at 1000°C was performed. The compressive strength and mineralogical composition of the samples were investigated before and after heat treatment. The results showed that the addition of argillite improved significantly the thermomechanical properties of kaolin-based geopolymers containing impurities, especially the mixture containing 67% argillite and calcined at 750°C. This phenomenon was not observed for the pure-kaolin geopolymer. Improvement of fire resistance was due to the formation in situ of leucite and zeolite-type phases (KAlSi2O6 and KAlSiO4) and of wollastonite (CaSiO3) at high temperature, which is linked to the Ca available in the raw materials. Keywords—Callovo-Oxfordian argillite (COx) . Carbonate . Geopolymer . Kaolin . Thermal resistance . Thermomechanical properties INTRODUCTION Fire resistance is an important property required in numerous applications. Geopolymer materials are characterized by high thermal stability which is generally related to the solidification of melted phases and/or the formation of thermally stable crystalline phases (Davidovits 1991; Duxson 2006). These three-dimensional amorphous binders result from the activation of an aluminosilicate source with an alkaline solution (Davidovits 1991). They can be synthesized from various aluminosilicate materials such as metakaolins, common clays, fly ash, blast furnace slags, etc. (Duxson 2006; Buchward et al. 2009a; Yao et al. 2009; Autef et al. 2013). According to the literature, the fire resistance of these materials can either be from viscous sintering and pore collapse (Duxson 2006) or due to the formation of thermally stable crystalline phases (Cheng and Chiu 2003; FernandezJimenez et al. 2008). The thermal behavior of a Na-based geopolymer which was characte
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