Avaliação do comportamento mecânico de solo residual em misturas com rejeito de minério de ferro

Abstract

With the advancement of mining activities in Brazil, the need arose to propose environmentally suitable methods for waste disposal. The utilization of iron ore tailings (IOT) in geotechnical projects emerges as a potential option to preserve natural soil by partially or entirely replacing the volume of soil with tailings. Moreover, this practice reduces the amount of waste disposed in dams or piles, thereby minimizing extensive disposal areas and the need for stability control. Furthermore, this reuse aligns with Goal 12 of the "Sustainable Development Goals" outlined in the Agenda 2030. Thus, this research aims to study the mechanical behavior of IOT and its mixture with mature residual soil to assess its potential in Geotechnical applications, such as pavement layers, road embankments, earth dam filters, landfill cover layers, and bricks or similar products formed by soil-cement mixtures. The study involves mineralogical and physical characterization tests, as well as mechanical tests and numerical modeling. The soil, IOT, and mixtures containing 25%, 50%, and 75% of tailings by dry mass of the mixture were investigated. Additionally, parameters of interest for a mixture of soil, tailings, cement, and sand were also obtained. This mixture was modeled as a cylindrical specimen using the PLAXIS 2D software to verify the compatibility of experimental results with the program's output. The results for pure materials and soil-tailings mixtures demonstrated improvements in mechanical parameters and increased stiffness for the mixtures. The tailings did not compromise any soil characteristics. The potential applications found were in road embankments, subgrade reinforcement, and landfill cover layers. Regarding the mixture with cement and sand, the obtained values indicate a potential use for soil-cement bricks. The modeling showed that the laboratory results are reliable and representative in terms of elastic modulus, Poisson's ratio, cohesion, and friction angle. Based on the obtained results and the literature review, it can be concluded that tailings are a potential raw material for geotechnical works and elements like bricks or similar products, which could reduce environmental impacts of mining, decrease the use of natural materials, and offer a new disposal method.