Permeability-Enhancing Drying Additives - A Perspective from in-situ Analysis

 The drying process of hydraulic bonded refractories represents a crucial bottleneck to the widespread adoption of this significant class of materials. Mitigating the risk of explosive spalling is of paramount importance as it entails extended heating procedures, resulting in substantial CO2 emissions and reduced end-user productivity. To minimize the occurrence of such explosions, two commonly deploying strategies involve the utilization of semi-empirically defined temperature plateaus and the incorporation of permeability-enhancing additives. Among these later, polymeric fibers have emerged as a preferred choice due to their cost-effectiveness and efficacy. Nevertheless, despite the ability to tailor various properties such as fiber melting temperature and melt viscosity, the underlying mechanisms by which these synthetic materials enhance permeability remain not clearly understood. Hence, the present study proposes the use of neutron tomography to provide insights into the influence of these fibers on the drying process. Notably, alterations in the velocity of the drying front and moisture accumulation were quantified. The anticipated outcomes of this investigation encompass advancing fundamental understanding of these mechanisms, providing practical guidelines to optimize the potential of polymeric fibers in averting explosive spalling, thereby inducing safer and faster drying processes for refractory castables.