Utilização de carepa de trefilação como agregado miúdo na fabricação de concreto de cimento Portland.

Abstract

The increasing concern about the environmental impacts, particularly regarding CO₂ emissions from Portland cement concrete production, which is responsible for approximately 8% of global carbon dioxide emissions, has led to the search for sustainable alternatives such as "green concrete." This aims to reduce the environmental impact of the construction sector through the use of more eco-friendly practices and materials. Based on this context, the present study aims to investigate the mechanical behavior of Portland cement concrete incorporating iron oxide particles from steel mill scale, a byproduct of the drawing process, as a partial sand substitute. The study explores the viability of this byproduct as a fine aggregate, analyzing its effect on concrete compressive strength. For this, test specimens were produced using a reference mix with crushed stone, sand, and water, to which varying amounts of mill scale (5%, 10%, 15%, and 20% by weight) were added as a replacement for sand. The methodology involved performing compression tests following ABNT NBR 5738 (2015) standards, using a universal testing machine. The curing period was varied at 7, 14, 21, and 28 days, with 60 test specimens analyzed. Data analysis was performed through average calculations and analysis of variance (ANOVA) to assess the influence of mill scale content and curing time on concrete's mechanical properties. Results showed that incorporating mill scale led to a reduction in compressive strength as the mill scale content increased. This reduction may be associated with contamination of the byproduct, the yet-to-be-determined ideal mix, and the concentration of compressive stresses in the mill scale region. ANOVA revealed that mill scale content significantly affects the mechanical properties of concrete. Visual inspection of the test specimens after testing confirmed acceptable fracture modes, though no direct correlation between fracture mode and mechanical property variation was found. In conclusion, while mill scale shows potential as an alternative material in concrete, further studies are needed to determine the optimal mix and mitigate the effects of contamination to enhance mechanical strength and material sustainability.