EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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9 resultados
Resultados da Pesquisa
Item Lignin-based admixtures : a scientometric analysis and qualitative discussion applied to cement-based composites.(2023) Carvalho, Victor Rezende; Costa, Laís Cristina Barbosa; Baeta, Bruno Eduardo Lobo; Peixoto, Ricardo André FiorottiThe development of lignin-based admixtures (LBAs) for cement-based composites is an alternative to valorizing residual lignins generated in biorefineries and pulp and paper mills. Consequently, LBAs have become an emerging research domain in the past decade. This study examined the bibliographic data on LBAs through a scientometric analysis and in-depth qualitative discussion. For this purpose, 161 articles were selected for the scientometric approach. After analyzing the articles’ abstracts, 37 papers on developing new LBAs were selected and critically reviewed. Significant publication sources, frequent keywords, influential scholars, and contributing countries in LBAs research were identified during the science mapping. The LBAs developed so far were classified as plasticizers, superplasticizers, set retarders, grinding aids, and air-entraining admixtures. The qualitative discussion revealed that most studies have focused on developing LBAs using Kraft lignins from pulp and paper mills. Thus, residual lignins from biorefineries need more attention since their valorization is a relevant strategy for emerging economies with high biomass availability. Most studies focused on production processes, chemical characterizations, and primary fresh-state analyses of LBA-containing cement-based composites. However, to better assess the feasibility of using different LBAs and encompass the multidisciplinarity of this subject, it is mandatory that future studies also evaluate hardened-sate properties. This holistic review offers a helpful reference point to early-stage researchers, industry professionals, and funding authorities on the research progress in LBAs. It also contributes to understanding the role of lignin in sustainable construction.Item Mechanical and durability performance of concretes produced with steel slag aggregate and mineral admixtures.(2022) Costa, Laís Cristina Barbosa; Nogueira, Marcela Aguiar; Andrade, Humberto Dias; Carvalho, José Maria Franco de; Elói, Fernanda Pereira da Fonseca; Brigolini, Guilherme Jorge; Peixoto, Ricardo André FiorottiThe steel slag is a residue for the steel industry that is already applied in many cement-based composites, although there is a lack of studies on the durability of this material in aggressive environments. This work evaluated the durability against chloride attack of concrete produced using steel slag as aggregate and mineral admixture, called steel slag powder. For comparison purposes, reference concretes using conventional aggregates and commercial mineral admixtures (silica fume and metakaolin) were produced. The concretes produced with steel slag aggregates and steel slag powder had lower chloride penetration depths compared to conventional ones. The steel slag powder presented an ability similar to silica fume of forming Friedel salt. The concrete produced with steel slag aggregates also presented a smaller water absorption and a higher compressive/tensile strength compared to the reference one. In general, this research observed that steel slag concretes are techni- cally feasible options for the construction sector.Item Eco-efficient steel slag concretes : an alternative to achieve circular economy.(2022) Costa, Laís Cristina Barbosa; Nogueira, Marcela Aguiar; Ferreira, Larissa Caroline; Elói, Fernanda Pereira da Fonseca; Carvalho, José Maria Franco de; Peixoto, Ricardo André FiorottiAnnually billions of tonnes of aggregates are extracted to apply in civil construction generating environmental impacts and energy consumption. So, based on circular economy principles applying residues as aggregates is a good solution to reduce the mining activity and to generate a more efficient destination for the residues. Thus, this research aims to evaluate the technical, economic, and environmental performance of concretes produced entirely with steel slag aggregates. The concretes were characterized through physical properties, as specific gravity, water absorption, compressive and tensile strength. Durability tests (expansibility) were also conducted. The authors analyzed the cost assessment and environmental impact of steel slag concrete production as well. The incorporation of steel slag increases the compressive and tensile strength of concrete, analyzed in different ages. Additionally, the steel slag does not present expansibility when confined in the concrete matrix. The entire replacement of natural aggregates for steel slag allowed to reduce in 31% the cement consumption, a decrease of 140 kg/m3 , for the same strength class. The environmental analysis showed that the incorporation of steel slag aggregates reduced the cement intensity of concrete and its impact. Regarding the cost assessment, the mixtures with steel slag presented a lower cost compared to the conventional one. These results indicate that steel slag aggregates could be used in a cleaner production of concrete, replacing natural aggregates with no injury. This research provides the feasibility of using steel slag aggregates in a cleaner and cheaper concrete production and contribute to the promotion of sustainable solutions for the construction sector through the circular economy principles.Item Steel slags in cement-based composites : an ultimate review on characterization, applications and performance.(2021) Martins, Ana Carolina Pereira; Carvalho, José Maria Franco de; Costa, Laís Cristina Barbosa; Andrade, Humberto Dias; Melo, Tainá Varela de; Ribeiro, José Carlos Lopes; Pedroti, Leonardo Gonçalves; Peixoto, Ricardo André FiorottiSteel slags are by-products generated in high volumes in the steel industry. Their main constituents are calcium, silicon, ferric, aluminum, and magnesium oxides. Larnite, alite, brownmillerite, and ferrite are also found. The presence of expansive compounds cause concern when used in cement-based compos- ites; however, mitigating routes have been proposed. Activation techniques improve the binding proper- ties of steel slag powder, potentiating its use as a supplementary cementitious material (SCM). As an aggregate, steel slag presents good morphological and mechanical properties. Promising mechanical and durability performances in cement-based composites encourage further research to promote the use of steel slag.Item Mechanical performance and resistance to carbonation of steel slag reinforced concrete.(2021) Andrade, Humberto Dias; Carvalho, José Maria Franco de; Costa, Laís Cristina Barbosa; Elói, Fernanda Pereira da Fonseca; Silva, Keoma Defáveri do Carmo e; Peixoto, Ricardo André FiorottiThe use of residues as alternative materials in the production of cement-based composites is significantly growing since it embraces the circular economy concepts. This alternative reduces the demand for nat- ural resources by the construction sector and provides a proper destination for a range of industrial resi- dues. However, the alternative materials must perform properly for safe applications. In this way, the steel slag, a residue of the steel industry, stands out. The steel slag is already applied in some cement- based composites showing enhancement in the mechanical performance, although its durability is barely evaluated. So, this research produced eco-friendly structural concretes of three compressive strength classes and for similar application parameters. The evaluations were performed in concretes with total replacement of conventional aggregates by steel slag aggregates, containing no chemical admixtures and in the presence of a PCE-based superplasticizer. The mechanical performance and resistance to car- bonation of these products were evaluated. An accelerated carbonation test was proposed and adopted to better understand the carbonation phenomenon within the research timeframe. The steel slag concretes presented higher compressive strengths and reductions in carbonation depths up to 60% compared to conventional ones. These results corroborate the technical feasibility of applying steel slag as aggregates in cement-based composites.Item New methodology to analyze the steel–concrete bond in CFST filled with lightweight and conventional concrete.(2021) Natalli, Juliana Fadini; Xavier, Ellen Martins; Costa, Laís Cristina Barbosa; Rodrigues, Bárbara Héllen; Sarmanho, Arlene Maria Cunha; Peixoto, Ricardo André FiorottiThe construction sector is constantly seek- ing for new building systems that are cheaper, faster and with a reduced generation of residues. In this way, the use of concrete-filled steel tubes (CFST) increased due to its fast and clean execution, and its high mechanical strength, durability and ductility. The performance of this system depends on the steel– concrete interaction that occurs in the form of a natural bond. The present work evaluates the natural bond mechanisms manifested in thin-walled steel tubes filled with three types of concrete: conventional, lightweight and lightweight with expansive admix- ture. Push-out tests were realized in the CFSTs and the results were compared with bond strength values prescribed by international standards. Finally, the residual concrete adhered to the CFST interface was evaluated by a new methodology using visual resources. Results indicated that the lower modulus of elasticity of the lightweight concretes contribute to the enhancement of the confinement effect and microlocking. And the expansive admixture improved the adhesion performance of the filling core. Addi- tionally, the new methodology presents a good correlation with the other tests and it is easy to apply.Item Correlation between ultrasonic pulse velocity and thermal conductivity of cement-based composites.(2020) Mendes, Júlia Castro; Barreto, Rodrigo Rony; Costa, Laís Cristina Barbosa; Silva, Guilherme Jorge Brigolini; Peixoto, Ricardo André FiorottiThe thermal conductivity of construction materials is among the main factors influencing the thermal performance of buildings. This property is, thus, extensively demanded for design purposes. The thermal conductivity is especially related to the pore system and the composition of cement-based composites, the same factors that affect their Ultrasonic Pulse Velocity (UPV). In this sense, the present work evaluates the correlation between thermal conductivity and UPV. To this purpose, mortar specimens were investigated, with varying mix proportions, fine aggregate types, and dosages of air-entraining admixture. A satisfactory determination coefficient (R2 > 0.9) was obtained between thermal conductivity and UPV of the mortars when they were grouped under similar components and pore structure. It was observed that the pore system of the mortars tested is more influential to the UPV than their overall porosity. In this sense, a better correlation was found between UPV and thermal conductivity than between thermal conductivity and specific gravity. Additionally, the fine aggregate type presents a significant impact—not only due to its chemical and mineralogical properties but also as a result of the morphology that each aggregate generates within the matrix. In conclusion, this technique potentially presents high applicability to the thermal characterisation of cement-based composites.Item Design and thermal evaluation of a social housing model conceived with bioclimatic principles and recycled aggregates.(2019) Franco, Luiza Carvalho; Mendes, Júlia Castro; Costa, Laís Cristina Barbosa; Pira, Rúbia Ricceli; Peixoto, Ricardo André FiorottiThe present work discloses the design and thermal evaluation of single-family houses adapted with bioclimatic principles to tropical climates – the Vila Sustentável complex. The architectural layout of each 2-bedroom unit embraces accessibility measures and bioclimatic strategies for energy-efficiency. The envelope embodies an innovative approach: the full replacement of natural aggregates by processed steelmaking slag in all cement-based composites (mortars, concretes and concrete blocks). These building elements were characterized physically and thermally. Subsequently, the thermal performance of the buildings was evaluated through an energy simulation using the software EnergyPlus. Results indicated that the stack effect designed in the living room promotes high ventilation rates with no energy consumption. The building elements produced with steel slag presented better thermal performance than the conventional ones, due to the high thermal inertia and low thermal conductivity of the slag. In this sense, the passive strategies proposed are replicable and energy-efficient alternatives for tropical countries.Item Desempenho de concretos de escória de aciaria frente a ataque de cloretos.(2019) Costa, Laís Cristina Barbosa; Peixoto, Ricardo André Fiorotti; Silva, Guilherme Jorge Brigolini; Peixoto, Ricardo André Fiorotti; Souza, Flávio Teixeira deEm 2017, o Brasil fabricou 34,4 milhões de toneladas de aço, sendo a nona maior produção mundial. Essa atividade gera diversos resíduos e coprodutos, destacando-se a escória de aciaria, que em sua maioria tem destinos pouco nobres, como aterros, depósitos e revestimento para vias secundárias. Estudos recentes comprovaram que concretos com escória de aciaria tem desempenho mecânico equivalente ou superior aos convencionais. Porém, existem poucas pesquisas avaliando a durabilidade dos mesmos. Os ambientes sujeitos ao efeito das marés são os mais perigosos para estrutura de concreto armado devido presença de cloretos que levam a diminuição da seção das armaduras e subsequente fissuração do concreto. Assim, esse trabalho avaliou a durabilidade frente a ataque de cloretos de concretos fabricados utilizando de escória de aciaria como agregado e adição mineral. Nessa pesquisa foram produzidos concretos com dois consumos de cimento (310 kg/m³ e 450 kg/m³). Com finalidade de comparação, foram fabricadas matrizes de referência utilizando agregados convencionais e adições minerais comerciais, como sílica ativa e metacaulim. Inicialmente todas as matrizes foram caracterizadas quanto as suas características físicas e mecânicas, tais como índice de vazios, massa específica, resistência à compressão e resistência à compressão por tração diametral. Subsequente, foi analisado a resistência a penetração de cloretos, através da exposição de corpos de prova a soluções agressivas de NaCl por períodos de 35 e 55 dias. Após esse período foi avaliado as profundidades penetradas por cloretos e a capacidade de formar sal de Friedel das três adições minerais utilizadas. De forma geral, os concretos com agregado convencional apresentaram menor índice de vazios e menor massa específica, os diferentes consumos de cimento não afetaram significativamente essas características. No entanto, apesar dos maiores índices de vazios, as matrizes fabricadas com agregado de escória de aciaria possuem resistência à compressão e à tração superiores aos convencionais. O aumento do consumo de cimento proporcionou uma melhora no desempenho mecânico dos concretos produzidos com ambos os agregados. A adição mineral de escória de aciaria apresentou comportamento semelhante à das adições comerciais quando combinada aos dois tipos de agregado e nos dois consumos de cimentos. Suas características físicas e mecânicas foram principalmente similares as matrizes produzidas com incorporação de metacaulim. Com relação a durabilidade, os concretos produzidos com agregado de escória de aciaria tiveram menores profundidades de penetração de íons cloretos quando comparado aos convencionais. O aumento do consumo de cimento implicou na produção de concretos mais duráveis, com menores profundidades atacadas. Avaliando a capacidade de formar cloretos combinados (Sal de Friedel) a adição mineral de escória de aciaria apresentou comportamento similar a sílica ativa. O maior teor de cloreto combinado foi notado no concreto com metacaulim. De modo geral, nessa pesquisa observou-se que agregados e adições minerais produzidas com escória de aciaria são opções tecnicamente viáveis para fabricação de concretos.