Abstract: Refractory materials from kaolinitic clays and clay chamotte or quartz were studied to increase the refractoriness
under load at temperature above 1300°C. Two different clays mined in Burkina Faso were used and chamotte grains were
obtained by preliminary firing a local clay. Fired materials at 1350-1400°C present a typical granular composite microstructure
where large grains of chamotte or quartz are embedded in the clay matrix phase. Under load at high temperature, the behavior
of material is influenced by the nature of the clay matrix phase that progressively melt at high temperature, the type of
chamotte or quartz grains, the grain sizes of different phases and the sequence of the thermal transformations during firing.
Kinetics of creep under a constant load were characterized against temperature and time. It gives the typical temperatures at
fixed creep strains, that’s a well-recognized method for the refractoriness quantification. It’s shown that the kinetic of creep
change with the variation of viscosity with temperature of the melted clay matrix phase, that’s related to both the chemical
composition and the extend of the micro-composite nature of the heat transformed clays. Results also indicated that values of
activation energy for creep are correlated to the refractoriness of materials.
Keywords: Clay, Chamotte, Mullite, Refractoriness

Clay, Chamotte, Mullite