Aplicação de cinzas provenientes da queima de resíduos têxteis na geotecnia: uma abordagem experimental com foco na resistência ao cisalhamento

Abstract

The production of non-renewable industrial solid waste without proper management or reuse strategies poses a significant environmental problem, especially when such waste is disposed of or treated without due care. One example of this issue is the use of textile waste as fuel in ceramic factory kilns, which results in the generation of ashes. Although these ashes are byproducts of the process, they often lack appropriate disposal or effective reuse, exacerbating environmental impacts. Therefore, this study aims to evaluate the potential reuse of waste derived from the combustion of textile residues in geotechnical applications, focusing on shear strength. The materials investigated in this study consist of sandy soil, textile ash, and a soilash mixture. The soil was collected from a rural road, while the textile ash was obtained from a red ceramic factory located in the municipality of Russas-CE, Brazil. The samples were sent to the Russas Campus of the Federal University of Ceará (UFC), where they underwent geotechnical, mechanical, and chemical characterization. Additionally, the mechanical behavior of the textile ash was evaluated through compaction and shear strength tests. For the preparation of the soil-ash mixture, an effort was made to optimize the particle arrangement to minimize void volume, employing the Andreasen model. The physical characterization results of the analyzed soil indicated a predominance of fine and medium sand particles, with a small fraction of silt and an almost complete absence of clay. In contrast, the textile ash was composed mainly of fine and porous particles, exhibiting a high moisture retention capacity and a significant void ratio. The chemical analysis of the ash identified the presence of metal oxides and other compounds that may influence the material’s reactivity. Regarding particle packing, it was found that an optimal composition with a lower void ratio and higher compactness was achieved when the mixture consisted of 74% soil and 26% textile ash. The shear strength tests demonstrated that the addition of textile ash to the soil resulted in a material with higher resistance to shear stresses, an increased internal friction angle, and a lower void ratio compared to the soil alone. Deformations in the mixture under normal stresses were reduced by approximately 60% when compared to those of the individual soil and ash samples, as the mixture exhibited better compactness due to improved structural particle rearrangement. Finally, in addition to enhancing shear strength when combined with soil, the conducted tests demonstrated the potential of textile ash for use in mixtures, highlighting its viability as an alternative material and its contribution to mitigating the environmental impacts caused by the textile and ceramic industries.