Fig. 7. Relative water content difference with respect to the initial state for the samples heated using the fast and slow protocols. The dashed lines can be used to infer the temperature distribution on the sample by the infrared’s temperature. This might be related to the dehydration reactions occurring at this position. After that, the water removal rate stabilizes around the 0.15 %/min, until the end of the experiment (also shown by the linear behavior, with r² = 0.99). For the slow heating, the behavior is similar but delayed, with the maximum peak taking place around 41 minutes. This is a strong indication that this peak is in fact related to a thermally activated chemical reaction of dehydration. After this event, the drying rate decays until reaching a constant stage. Nevertheless, it is interesting how the water removal rate is considerable higher, around 0.45 %/min. The reason for this later faster water removal, for the sample that was heated slowly, might be related to the presence of the temperature plateau. If, for instance, the final temperature was the common operating temperature found in the industry, it is believed that the sample heated by the fast protocol would finish its drying earlier. Fig. 8. Evolution of relative difference for top and bottom slices of the sample and the respective rates for the slow heating and fast heating cases. Further studies with temperature measurements and with longer heating protocols are necessary to further understand this unexpected behavior. Nonetheless, these findings highlight the complexity of designing heating schedules and how the temperature plateaus need to be well understood and justified to promote safer drying process. CONCLUSIONS The drying of refractory castables is a complex subject which requires interdisciplinary efforts, ranging from numerical methods, experimental techniques and knowledge of the industrial perspective. Advanced non-intrusive techniques originally applied to Portland cement concrete can provide unprecedented findings. In the current