Avaliação da degradação físico-química da mistura binária álcali-ativada de resíduo de cerâmica vermelha e escória panela

Abstract

Portland cement production is one of the main sources of CO₂ emissions in the construction industry, driving research into more sustainable alternative binders. This research evaluated the durability of alkali-activated pastes produced with binary mixtures of red ceramic waste (RCV) and ladle furnace slag (PAN), activated with NaOH and Na₂SiO₃ solutions in different proportions. Six formulations were developed varying the precursor content (70/30, 50/50 and 30/70% RCV/PAN) and the activator ratio (60/40 and 40/60% NaOH/Na₂SiO₃). The pastes were characterized in the fresh and hardened state and subjected to durability tests in aggressive environments: 5% H₂SO₄ solution, 10% MgSO₄, 3% NaCl and natural seawater, in immersion-drying cycles. Two formulations were also evaluated after accelerated carbonation curing. The results demonstrated that the mixtures with higher PAN content (70%) and a higher proportion of sodium silicate showed the best performance, achieving compressive strengths greater than 40 MPa at 28 days and maintaining or increasing mechanical strength after exposure to aggressive environments, with mass losses generally less than 5%. Microstructural analyses (FTIR, TG/DTG, and MIP) revealed the formation of dense matrices with stable C-A-S-H and N-A-S-H gels, reduced porosity, and greater resistance to leaching and chemical degradation, especially in saline and sulfate environments. Accelerated carbonation proved beneficial for calcium-rich mixtures, improving stability in chloride media. The findings confirm the high potential of RCV-PAN binary mixtures as a sustainable alternative to Portland cement, with excellent durability in aggressive conditions and a contribution to the circular economy through the valorization of local industrial waste.