Análise de misturas sustentáveis: o potencial do gesso reciclado e resíduos industriais na construção civil

Abstract

The growing search for sustainable solutions in the construction industry has encouraged the use of industrial waste as alternatives to Portland cement, due to the environmental impacts caused by its production. In this context, this thesis aimed to develop cementitious materials that meet regulatory standards and have potential for use in paving, using recycled gypsum, blast furnace slag, and fly ash as partial cement substitutes. The work was divided into two major phases. The first consisted of a systematic literature review, aiming to map the main types of waste used as alternative cementitious materials, identify common replacement ratios, and compile key tests conducted in national and international research. This phase enabled the identification of gaps and the definition of parameters and tests for the experimental design of the research. The second stage comprised the experimental phase, structured around the methodology for physical, chemical, and morphological characterization of the waste (recycled gypsum, blast furnace slag, and fly ash), using techniques such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Subsequently, cementitious mixtures with different proportions of waste were mixed, molded into specimens, and subjected to mechanical strength tests according to specification and flexural tensile strength, water absorption, and durability (abrasion and freeze/thaw cycles in fresh and salt water). The results demonstrated that mixtures with up to 12.5% recycled gypsum had superior performance, with characteristic strengths above 35 MPa, meeting the requirements of Brazilian and international paving standards. Mixtures with the addition of all three components had acceptable technical performance, despite regulatory limitations, and are recommended for non-structural applications. Durability tests showed greater absorption in saline environments, requiring the use of mitigating additives. Abrasion and thermal cycling tests confirmed the potential of compositions with lower substitution rates. The conclusion is that the combined use of industrial waste as a partial replacement for cement is technically, economically, and environmentally viable, contributing to reducing environmental impacts, increasing waste recovery, and promoting a circular economy in the construction industry.