Reaproveitamento de refratário Al2O3-ZrO2-SiO2 (AZS) como agregado em concretos aluminosos

Abstract

The refractory industry plays a significant role in various industrial sectors, being essential for production processes conducted at high temperatures and under adverse conditions, such as in the presence of corrosive environments, high mechanical wear, and involving substantial deformations and stresses. However, these ceramics have a limited service life, generating waste that is currently underutilized and applied in situations that do not take advantage of the high added value of these materials. This study evaluated a potential alternative for better waste management. For this purpose, the effects of incorporating different amounts of recycled alumina-zirconia-silica (AZS) refractory aggregate (originating from the glass industry) into alumina-based concretes were investigated. Initially, the recycled aggregate was characterized regarding its chemical composition and the crystalline phases present. Subsequently, various castables were prepared and evaluated for their flowability, apparent porosity and density, linear dimensional variation, flexural strength, and thermal shock resistance. After firing at 1400°C, an increase in mechanical strength was observed in the composition containing 10 wt.% of recycled AZS aggregates (44.50 MPa) compared to the reference castable (23.73 MPa). Additionally, higher thermal shock resistance was obtained for the composition containing 5 wt.% of recycled aggregates, with a decrease in samples’ stiffness of only 13.31% after 10 thermal shock cycles (ΔT ~ 1000°C). Thus, this work demonstrates the potential for reusing alumina-zirconia-silica refractories at the end of their service life, as they can be incorporated as recycled aggregates into alumina-based refractory castables, providing benefits to the properties of these products.