Programa de Pós-Graduação em Engenharia Civil
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Master Thesis Estudo da pasta de cimento com substituição parcial e total da água de hidratação por manipueira(Universidade Federal do Rio Grande do Norte, 2021-07-28) Pipolo, Lisieux Feitosa Gondim; Acchar, Wilson; Silva, Vamberto Monteiro da; 0000-0002-2291-8555; http://lattes.cnpq.br/7962325767490100; Lucena, Luciana de Figueiredo Lopes; http://lattes.cnpq.br/5893551656862490; Silva, Jaqueligia Brito da; http://lattes.cnpq.br/5948828937239319; Marques, Sheyla Karolina Justino; http://lattes.cnpq.br/3917387578549073Cement paste is the union of two inputs: water and cement. From it, concrete and mortar are prepared, which are the most consumed elements in the construction industry. Given this great demand, some questions arise about the environmental impact of the high consumption of natural resources. In this sense, researches have been developed to minimize the consumption of non-renewable goods by replacing them with products from other productive activities. Within this perspective is manipueira, a liquid by-product resulting from the pressing process of cassava roots with a high content of hydrocyanic acid and high biochemical oxygen demand. Its disposal is normally done in water bodies, causing changes in the self-purification and eutrophication capacity, or through accumulation in small areas surrounding the production site without prior treatment. Considering that in 2020 Brazil was responsible for the production of 18.96 million tons of cassava root, studies to mitigate this environmental impact are relevant. The objective of this research is to analyze the behavior of cement paste produced with manipueira as a substitute for water, in terms of physical and mechanical properties and microstructure. The materials were characterized and seven pastes prepared with different replacement contents (10%, 15%, 20%, 25%, 50%, 75%, and 100%) for analysis of properties in the fresh and hardened state. In the fresh state, the presence of manipueira caused a delay in setting time up to 66% about the reference paste and plasticizing behavior to the cement pastes in all the proposed formulations. In the hardened state, an increase in compressive strength of 28% was found in the formulation with 20% replacement, and a sharp drop in the proportions of 75% and 100% replacement when compared to the reference paste. It was also verified a decrease in specific mass, increase in the void index, and capillary absorption in all replacement ratios. From the results found, microstructural analyzes were performed on samples of 20% and 100% compositions. It was noticed the formation of hydrated silicate flakes (CSH) in the paste with 20% replacement, and late ettringite in the paste with 100%. Thus, it is concluded that the studied manipueira can be used in cement pastes replacing up to 20% of the hydration water since its properties have been improved. However, the incorporation of manipueira in higher levels of replacement harmed the cement hydration process.Master Thesis Avaliação do ciclo de vida de agregados leves artificiais produzidos com resíduo industrial e argila vermelha local (Nordeste/Brasil)(Universidade Federal do Rio Grande do Norte, 2020-10-09) Rocha, Débora Patrícia Batista da; Anjos, Marcos Alyssandro Soares dos; Lucena, Luciana de Figueiredo Lopes; ; http://lattes.cnpq.br/5893551656862490; ; http://lattes.cnpq.br/3904325866154130; ; http://lattes.cnpq.br/3372872328936393; Almeida, Maria das Vitorias Vieira; ; http://lattes.cnpq.br/7590200701773198; Nóbrega, Claudia Coutinho; ; http://lattes.cnpq.br/8208309251703934The 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.Master Thesis Aplicação geotécnica de resíduo de mineração em sistemas de cobertura final de aterros sanitários(2020-03-19) Gondim, Tiago Feitosa; Ingunza, Maria Del Pilar Durante; Freitas Neto, Osvaldo de; ; ; ; Santos Junior, Olavo Francisco dos; ; Severo, Ricardo Nascimento Flores;The use of mining residues within production chains, such as civil construction, is an important environmental solution for mining activities in Brazil. Researchers have shown that different types of mining residues can be incorporated into some types of geotechnical works, fulfilling the function of hydraulic barrier. In this scenario, the use of scheelite residue in environmental geotechnics works could be an environmentally sustainable solution for this material. This work aims to evaluate the technical viability of using two scheelita mining residues as a compacted coating with hydraulic barrier function in waste landfill covering systems. Physical characterization, compacting, hydraulic conductivity on rigid and flexible wall permeameters, XRF/XRD and SEM and erodibility tests were performed on four materials formed by mixing two residues generated during the scheelite processing at the Brejuí Mine in Currais Novos/RN. In the tests, samples were conformed by the two residues used, varying from the fine residue exclusively, and departing for variations of 25% by mass of the coarse residue content (F100, F75G25, F50G50 and F25G75). The obtained results demonstrate the technical viability of the intended use of the material. The F100 and F75G25 samples proved to be viable for the intended application (hydraulic barrier in landfill covering), meeting international normative requirements. The other composites (F50G50 and F25G75) could be applied for other purposes within a waste landfill: as regularization and/or protection layers. During the hydraulic conductivity tests, it was observed that, in the samples that contained a higher percentage of fine particles (< 0,075 mm), there was a progressive decrease in the permeability of the compacted material, from 1,76x10-6 to 2,18x10-8 m/s, but not necessarily a significant variation in the density or porosity, indicating that the incorporated fines filled the voids of the larger particles increasing the flow tortuosity. The decrease in permeability can be explained by morphological factors specific to the material used.