Caracterização de escórias de aciaria e avaliação do seu uso na produção de argamassa de revestimento

Abstract

The steel industry is an important supplier of inputs for civil construction, its world production in 2017 worth 1.7 billion tons of crude steel and the national value of 34.4 million tons. However, the steel industry produces a significant amount of waste, including steel slag, represented by 27% of total co-products and direct residues produced in Brazil in 2017, or 5.64 million tons. The majority of this waste is currently used in roads and sub-bases (50%), as well as land and landfill leveling (42%). Thus, the incipience of the reuse of steel slag as an aggregate in mortar for civil construction is observed, being a sector that requires a great quantity of raw material since it demands between 14% and 50% of the natural resources of the planet. The present study aims to characterize five different steel slags and evaluate the technical viability of the partial replacement of natural aggregate (sand) by recycled aggregate from the BSSF slag (Baosteel Slag Short Flow) in production of mortar. It should be noted that the characterized waste comes from Companhia Siderúrgica do Pecém / CE. For chemical and mineralogical analysis, were perfomed the XRF and XRD tests, respectively; as well as the granulometry tests, determination of the content of material passing through the 75 μm, absorption and specific mass for the physical analysis of the alternative materials. Mixed mortars were produced with the usual mix in the proportion of cement, hydrated lime and wet sand 1: 1: 6 by volume; being 50kg of cement, 20kg of hydrated lime and 6 cans of wet sand; typically used in Fortaleza to facade cladding. Four mixes were performed, one of them being a reference (without recycled aggregate) and three mixes (10%, 20% and 30% of BSSF recycled aggregate replacing the natural aggregate). In the fresh state, the workability was analyzed through the consistency index, the incorporated air content and the mass density. In the hardened state, test specimens were produced, evaluating the mechanical properties of the mortar, through tests of resistance to axial compression and tensile strength in flexion at the ages of 7 and 28 days. Panels were perfomed, in masonry, for the analysis of the resistance of adhesion to the traction and evaluation of the watertightness by the pipe method. The results were evaluated by analysis of variance, ANOVA, and satisfactory results were obtained for the application of BSSF slag to the production of coating mortar in the 10% content.