Novel Technological Route to Overcome the Challenging Magnesia Hydration of Cement-free Alumina Castables

Tiago M. Souza, Mariana A. L. Braulio, Victor C. Pandolfelli

Federal University of São Carlos, GEMM, Materials Engineering Dept., 13565-905 São Carlos – SP/Brazil

Revision 05.06.2012, 17.09.2012

Volume 5, Issue 1, Pages 93 - 98


Due to the expansive behavior associated with the brucite [Mg(OH)2] formation, magnesia hydration is a challenging subject in the refractory castable area. Although various anti-hydration techniques have been suggested in the literature, a technological solution for this issue has not yet been presented. Instead of inhibiting brucite formation, speeding up its formation could be a suitable microstructural engineering resulting in the Mg(OH)2 accommodation in the castable pores and increasing the green mechanical strength of the castables, without crack formation. Therefore, acetic acid was selected and added as a hydrating agent, affecting the amount of brucite generated and also its morphology. As an overall result, the reaction was accelerated and provided some structural flexibility to the Mg(OH)2. This interesting alternative route can result in technological advances on the understanding and use of higher magnesia amounts in cement-free refractory castable compositions.


refractory castables, magnesia hydration, acetic acid


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