Utilização de cinza de biomassa de madeira na produção de concretos de ultra alto desempenho: uma abordagem sustentável

Abstract

This study investigates the potential use of mixed wood biomass ash as a partial substitute for cement and active silica in the production of Ultra High Performance Concrete (UHPC), seeking to reconcile mechanical performance and sustainability. The research addresses the problem of the high environmental impact associated with Portland cement production and the need to reuse industrial waste, proposing the use of a by-product from the paper industry. The methodology was based on the physicalchemical and mineralogical characterization of the ash, followed by the production of cementitious composites using three strategies for incorporating mixed wood biomass ash: direct addition, partial replacement of cement, and partial and total replacement of active silica, at percentages of 5%, 7%, 10%, and 15%. A total of 252 prismatic test specimens (4 x 4 x 16 cm) were molded and subjected to moist heat curing and mechanical tests of flexural and compressive strength at 7, 14, and 28 days, followed by microscopic characterization by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for post-failure microstructure analysis. The results indicated that the incorporation of mixed wood biomass ash, at levels of up to 10%, promoted an increase in mechanical strength, especially in the partial replacement of active silica, and favored the densification of the concrete matrix. It was also observed that the use of this residue contributes to reducing the demand for non-renewable raw materials and emissions associated with the production of cement and silica. It is concluded that mixed wood biomass ash has high technical and environmental potential for application in UHPC, making it a viable alternative for waste recovery and for strengthening sustainable practices in civil construction.