Experimental study of the drying and modelling of the humidity migration in a clay matrix

¹ Laboratoire d'Études et de Recherches sur les Matériaux, les Procédés et les Surfaces (LERMPS) Équipe de Recherche sur les Agro-Matériaux et la Santé Environnementale (ERAMSE), Département de Génie Mécanique et Conception, Université de Technologie de Belfort-Montbéliard, 90010 Belfort Cedex, France
² Civil Engineering Department, École Royale Militaire de Bruxelles, Belgique
³ Laboratoire de Mécanique Appliquée, R. Chaléat (LMARC), Université de Franche-Comté, 25030 Besançon, France

Corresponding authors: kokou-esso.atcholi@utbm.fr katcholi@hotmail.com

Received: 18 June 2007
Accepted: 2 January 2008

Abstract

Available almost everywhere, therefore economic and even so durable, clays have stimulated the creativity of men who have imagined since millennia and under all latitudes, multiple processes to develop pottery (faïence enameled, porcelain, ceramics) and construction materials. These materials compete with modern materials in civil engineering for important construction works such as bridges, roads, tunnels, monuments etc. In state-of-the-art technologies, clay ceramics are used as anti-thermal coatings: turbine vanes, etc... The weakness of our scientific knowledge limits applications of these natural materials. This study on tropical clays, has for objective on one hand to develop new processing of construction materials for lodging needs that are more and more increasing in the developing countries, and the other hand to develop new refractory materials, anti-thermal coatings or ceramic prostheses. This study is part of a research program and academic cooperation between the laboratories LMARC-Besançon/France, LERMPS-Belfort/France, Civil Eng. Dept./ERM-Bruxelles/Belgique, URMA-Lomé/Togo (K.-E. Atcholi, Rapport d'activités de Recherches, Université de Lomé, Février 1997). In this paper, we present an experimental modelling of a clay matrix drying in order to better understand and resolve material deformations and cracking. The complex behaviour of the clay during drying, leads us to propose two complementary approaches: an experimental approach that allows to establish the drying kinetic and a modelling of moisture transfer in a clay matrix in order to optimise the drying. A diffusive model based on Fick's laws allowed to highlight the internal stresses causing matrixes damage.