Neutron Tomography Analysis of Drying - Proof of Moisture Clog and Heating Rate Effects
Résumé
The drying of refractory monolithics is one of the main drawbacks of this class of materials due to its implication on the production halt of many industrial equipment. This is especially true for calcium aluminate cement (CAC)-bonded castables, where the vapor derived from the unreacted water and dehydration reactions can pressurize yielding cracks and explosions of the ceramic lining. Numerous advances on additives have been made to increase these materials' resistance to explosive spalling, however, the fundamentals of the physical phenomena that yields such a problem remain an open issue. For years, the techniques used to study this process were limited to indirect tests, such as the thermogravimetric analysis or the pressure and temperature measurements of samples being unidirectionally heated. Recently, direct techniques such as nuclear magnetic resonance and X-ray tomography were applied in the context of regular concrete on fire scenarios. The current work presents preliminary results of neutron tomography applied to monitoring the drying of refractory castables. The drying front shape and velocity was directly affected by the presence of a ceramic casing around the sample. This also increased the moisture accumulation commonly known as moisture clog. The effect of different heating rates was also assessed and the current framework proposed herein can be successfully applied to increase the understanding of the drying, specially when considering its use in conjunction to numerical models.