External validation of the recently reported drying theory

Even though developed drying theory and Deff-MR curves were successfully used, for modelling the suitable drying regimes of roofing tiles on laboratory and industrial scale during last 15 years, its theoretical contribution as a tool on which all internal moisture mechanisms can be easily registered is still not close enough to the brick and tile companies. The main goal of this paper was to additionally externally validate the developed drying theory and to reveal the universal potential of variable Deff-MR curves for various drying application. The first step was to digitalize the various MR vs – time and MR vs linear shrinkage data taken from the literature. These data were further processed in accordance with the reported drying theory. Deff – MR curves were constructed in the next step. These curves were compared with the originally reported one. The shape of curves was at the first sight similar but after a close look actually all deviation of original data from fitted Deff - MR curves had its theoretical explanation. The transition points of internal mechanisms registered on theoretical Deff – MR curve were revealed on externally taken literature data. It is interesting that this pattern was revealed regardless to the fact that the calculation method for time-dependent Deff coefficient was different. This was reliable external validation proof that that the developed drying theory and Deff-MR have universal theoretical and practical significance.