The size effect on the drying behavior of castables - An experimental and numerical perspective

Refractory castables present many attractive features. However, for hydraulic bonded monolithics, the major drawback is the long drying stage during its placement due to the likelihood of explosive spalling. The latter is a direct consequence of non-optimal management of the thermal and hygral states that leads to pressurization of water vapor and can induce severe damage to the lining. This phenomenon results in overconservative heating schedules which leads to longer production halts, economic losses and environmental effects. From numerical models to advanced laboratory tests, the missing link between fundamental research and technology innovation relies on the size scale difference among the samples studied in the labs and those lining the refractory equipment. The current study proposes a systematic analysis of the size scale effect by considering conventional thermogravimetry (50mm x 50mm cylindric samples), macro thermogravimetry (30 cm x 30 cm x 30 cm cubic samples) and also numerical simulations of different heating configuration to unveil likely relationships between different scales and the experiments setups and actual drying process. It was found out some interesting correlation between the mass loss of the macro TGA and the lab one testing a smaller sample size. Further studies to identify and validate the existence of a general scaling law are required, nonetheless, the current study provides a first step towards finally bridging the gap between small laboratory samples and real industrial geometries.