Uso da areia descartada de fundição (ADF) em substituição parcial ao cimento portland: análise das propriedades mecânicas de argamassas contendo o resíduo in natura e calcinado

Abstract

The cement industry has discussed ways to reduce carbon dioxide emissions, especially due to Portland cement production. Concurrently, the foundry industry generates high volumes of waste foundry sand (WFS), whose predominant disposal still occurs in industrial landfills. In this context, the present study evaluated the use of WFS as a partial replacement for Portland cement in mortars, comparing the performance of the residue in natura and after calcination at 1000 °C. Mortars were produced with replacement levels of 5%, 10%, and 20% relative to the cement mass, maintaining a water/cement ratio of 0.48. The mixtures were characterized in the fresh state by the consistency test and, in the hardened state, by compressive strength tests at 7 and 28 days of curing. The results indicated a gradual reduction in the consistency of the mortars with increasing replacement levels, a behavior more evident in compositions containing 20% WFS. In the hardened state, both conditions of WFS incorporation showed an initial reduction in mechanical strength at 7 days. However, at 28 days, a significant evolution in strength was observed, highlighted by the mortars containing 10% replacement, in which the in natura WFS outperformed the reference mixture, while the calcined WFS showed an even higher mechanical performance, reaching the highest strength of the study (37.48 MPa). The observed loss on ignition (18.97%) evidenced the effectiveness of calcination in eliminating organic matter and volatile compounds, favoring the interaction of the residue with the cementitious matrix. Thus, the results demonstrate that the use of WFS shows potential for application in cementitious mortars, contributing to the reduction of Portland cement and to the sustainable valorization of industrial waste.