Avaliação do desempenho técnico de cimentos com resíduo da serragem de mármore

Abstract

The cement manufacturing process generates major environmental impacts from the exploitation of non-renewable resources, high energy consumption and greenhouse gas emissions. The partial replacement of clinker by mineral admixtures is considered a key issue to reduce carbon emissions from the cement industry and the synergy arising from the combination of different mineral admixtures with Portland clinker has been explored in research and in the standards of different countries. Although the use of limestone filler is a consolidated practice, its replacement by marble sawdust residue can contribute to the reduction of environmental loads of the ornamental stone industry and stimulate circularity. In this research, six cement formulations were studied, combining calcined clay, blast furnace slag, limestone filler or marble sawing waste, adopting a clinker factor of 50%. The technical performance evaluation had as reference the requirements and criteria standardized in ABNT NBR 16697:2018. Additionally, the mineralogical compositions of the hydrated phases were evaluated using X-ray diffraction. The cementitious efficiency at 7 and 28 days of age of the set of mineral additions and the intensity of greenhouse gas emissions of each cement at 3, 7, 28 e 91 days of age were also calculated. All the studied cements met the standardized requirements, with emphasis on the formulations with calcined clay, blast furnace slag and marble sawing waste, which reached compressive strengths of 28 MPa and 41 MPa, respectively at 7 and 28 days, and with blast furnace slag and marble sawing waste, which presented the lowest intensity of greenhouse gas emissions. This research demonstrated the potential of marble sawdust waste to replace limestone filler in the production of composite cements and that the synergy between alumina-rich mineral additions and limestone filler or marble sawdust waste allows reducing the clinker factor and greenhouse gas emissions in the cement industry, while preserving the mechanical performance required by construction market practices