Distribuições granulométricas e a permeabilidade de concretos refratários contendo fibras poliméricas

The drying process of refractory castables is a critical step on their processing due to the explosive spalling tendency during the first heat up. Polymeric fibers are incorporated to the castable's formulation (0.01-0.1%wt) in order to minimize or avoid these problems, but the fibers performance has not been completely explained so far. Understanding the castable's permeability enhancement mechanisms, can lead to the design of monolithics less susceptible to explosive spalling, with better quality and optimized drying schedules. The purpose of this work was to evaluate the influence of polymeric fibers addition with different lengths (0.1-24 mm) into castables with two distinct particle-size distributions based on Andreasen's packing model using distribution coefficient values q of 0.21 and 0.26. The samples were evaluated by low temperature permeametry (LTP, 25 °C) and porosimetry.