Avaliação do ciclo de vida de agregados leves artificiais produzidos com resíduo industrial e argila vermelha local (Nordeste/Brasil)

Abstract

The adoption of alternative materials has become an increasingly constant practice in civil construction in the search for sustainable solutions for the conservation of natural resources. The reuse of industrial waste in new construction materials has aroused growing interest in environmental impacts of the production of recycled aggregates to replace conventional aggregates. To this end, this study sought to measure the environmental impacts resulting from the production of artificial lightweight aggregates produced with sugarcane biomass ash (SCBA) and red clay from the Northeast of Brazil through the Life Cycle Assessment (LCA) methodology. For this, an industrial production proposal was prepared with specification of the stages and equipment, with the possibility of being adapted to different regions of Brazil. The LCA procedure followed four main steps, prescribed by the ABNT ISO 14040:2009 and ABNT ISO 14044:2009 standards: definition of objective and scope, inventory analysis, impact assessment and interpretation. The system boundary went from the cradle to the gate level and includes the stages of extraction, collection and processing of raw materials and production of lightweight aggregates. The environmental impacts were evaluated for three compositions of the artificial lightweight aggregate (pure clay, 50% replacement and 90% SCBA). The compositions were studied in three locations of the factory: Itajá/RN, Goianinha/RN and Parnamirim/RN. The inventory data were processed using OpenLCA 1.10 software using the CML 2001 non baseline method and midpoint approach. The impact categories studied were: acidification, eutrophication, global warming, human toxicity, ozone depletion, photochemical oxidants, terrestrial ecotoxicity, freshwater ecotoxicity and marine ecotoxicity. The results showed that the use of SCBA in the composition of lightweight aggregates allowed a reduction of up to 87.21% in the use of red clay as a natural resource, in two of the three scenarios analyzed. The aggregate compositions using SCBA showed lesser environmental impacts (except in the category of global warming) compared to the composition of pure clay in scenarios where the location of the factory is close to where the waste is obtained. The transport stages influenced significantly in all impact categories due to the use of fossil fuel (diesel) and the results are very sensitive to transport distances. The stage of burning light aggregates is highlighted in the global warming category. This study clearly showed that lightweight aggregates with the use of industrial waste can contribute to the reduction of environmental impacts during their production. The results can support decision-making processes and the development of similar LCA studies in lightweight artificial aggregates.