Uso de rejeito do beneficiamento de granito para substituição parcial de um solo em camadas de pavimentação

Abstract

The pollution produced by mining activity is one of the main issues discussed in today's society. Global concern on the subject raises mainly from the consequences endured by the planet, encouraging the adoption of effective and less damaging measures to the environment. Environmental issues caused by mining tailings generated at the granite processing stage are evidenced in the local context. The mining tailing used in this study originates from a mineral deposit encountered in the Seridó region of Rio Grande do Norte state, more specifically located between Caicó and São Fernando cities. Therefore, this study aims to partially replace the local soil with the incorporation of a mining tailing from granite processing in the proportions of 10%, 20% and 30% to the final mixtures of the paving layers. Trials were conducted at the Soil Laboratory of the Federal University of Rio Grande do Norte (UFRN) and NUPPRAR/UFRN in order to assess chemistry, mineral, physical and mechanical properties. The obtained results demonstrate that only the sample containing 10% of a mining tailing from granite processing (AM03) was efficient to the three types of paving layers (base, subbase and subgrade). The analysis of the other samples presented exceptions related to the CBR results or to the expansion. Furthermore, it was appraised the results of a simulation concerning economic feasibility of the sample that presented the best performance based on the cost of a road paving work auctioned by the Infrastructure Superintendency – INFRA/UFRN. The soil replacement in subgrade and base layers by the material accounted at zero cost caused a reduction of less than 1% of the total value of the work. Although the partial replacement of the soil by 10% of AM03 presents a low-cost reduction, the incorporation of such sample to the final mixture is sustained by environmental benefits that do not encumber the total value of the work.