Paper number 736

BEHAVIOUR OF ALUMINA REFRACTORY COMPOSITES FOR TEMPERATURES BELOW 800°C. EXPERIMENT AND MODELLING

J.F. Hernandez¹,³ N. Schmitt¹ P. Meunier² and J. Poirier³

1LMT-Cachan (ENS de Cachan, CNRS, Université Paris 6)
61, avenue du Président Wilson, F-94 235 Cachan Cedex, France
2Lafarge Monolitiques Réfractaires
97, avenue Aristide Briand, F-92 120 Montrouge, France
3CRDM / SOLLAC, Grande Synthe, BP 2508, F-59 381 Dunkerque, France

Summary

A study of the changes in the chemical, physical and mechanical properties of high alumina refractory castables was made for temperature below 800°C. The aim was to estimate the effects of the conversion of the hydrates contained in the binder. First, the principal steps of the dehydration were determined by X-Ray Diffraction and thermal analysis. Constitutive equations were proposed to characterise the phase transformations of the binder. The material parameters were identified by thermogravimetric analysis. Then, both the porosity of the cement paste, measured by mercury intrusion porosimetry, and the thermal shrinkage, measured by thermal dilatation tests were modelled using the previous chemical identification. Finally, the influence of the dehydration on the global properties of composites containing alumina-based aggregates was studied. Experimental data of the thermal shrinkage and Young's modulus obtained on composites with different aggregates contents were compared with a micromechanical model.

Keywords

concrete, alumina, dehydration, thermal analysis, modelling.