Estudo da influência da cinza da casca de arroz, escória de alto-forno e cinza leve no potencial de redução da emissão de CO2 decorrente da produção de cimento Portland

Abstract

Concrete is the most consumed artificial material in the world. Cement is the main constituent of concrete, which is one of the main causes of carbon dioxide emissions in civil construction. This study aims to evaluate the global warming potential of partially replacing Portland cement with rice husk ash, blast furnace slag and fly ash, and to analyze the influence of replacements in different levels on the mechanical properties of tension and compression in mortars. The Life Cycle Assessment (LCA) was conducted using the SimaPro tool, using the EcoInvent 3.11 and Agri-footprint databases, using the ReCiPe 2016 Midpoint Hierarchist method with cradle-to-gate boundaries excluding transportation and with a functional unit of 1 kg. The results showed that blast furnace slag was the material with the lowest environmental impact, despite the highest strength losses, with a reduction of up to 64% in CO₂-eq emissions. Rice husk ash provided a better balance between mechanical performance and environmental impact, especially at 30% content, with a 40% increase in compressive strength compared to the reference and a 15% reduction in kgCO₂-eq emissions. Fly ash provided the cement with good mechanical strength, but a high environmental impact linked to the energy demand in its production. The additions studied provided greater mechanical strength, with the exception of blast furnace slag in some cases, and reduced CO₂ emissions, in addition to promoting a reduction in the improper disposal of these materials and the demand for Portland cement clinker.