A influência do óxido de grafeno e da sílica coloidal nas propriedades químicas e mecânicas de matrizes cimentícias
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Data
2020-04-20
Tipo de documento
Dissertação
Título da Revista
ISSN da Revista
Título de Volume
Área do conhecimento
Engenharias
Modalidade de acesso
Acesso aberto
Editora
Autores
Bueno, Roberto Munhoz
Orientador
Salvador, Renan Pícolo
Coorientador
Resumo
Os nanomateriais têm sido amplamente empregados em indústrias de equipamentos computacionais, componentes eletrônicos, elétricos e químicos. Entretanto, ainda existem poucos estudos sobre seus impactos na construção civil, principalmente em concretos convencionais. Amplamente empregado na construção civil, concreto sempre foi objeto de estudos, principalmente voltado a adições para melhorar sua resistência, porosidade e durabilidade. As atuais adições empregadas no concreto influenciam em uma escala micro, atuando como partículas inertes ocupando espaços vazios ou com função pozolânica. O presente estudo avaliou a influência da adição de óxido de grafeno e de sílica coloidal nas propriedades químicas e mecânicas de matrizes cimentícias. Primeiramente, foi avaliado como o processo de produção de pastas de cimento influencia a dispersão de óxido de grafeno na matriz. Então, foi avaliado como as adições de óxido de grafeno e de sílica coloidal influenciam a cinética, os mecanismos de hidratação e a microestrutura de pastas de cimento. Finalmente, foi avaliado como esses compostos influenciam o desenvolvimento de resistência mecânica de concretos em idades iniciais e avançadas. Os resultados demonstraram que a adição do óxido de grafeno e de sílica coloidal aceleram as reações de hidratação de cimento, promovem a formação de C-S-H e densificam a microestrutura dos compósitos cimentícios. Além disso, tais compostos promoveram ganhos significativos na resistência à compressão de concreto. Com isso, foi possível recomendar reduções de 14% no consumo de cimento em concretos que contêm esses compostos, com o intuito de manter a resistência mecânica. O estudo realizado pode promover uma melhora significativa na tecnologia de concretos e na sustentabilidade do ambiente construído.
Nanomaterials have been widely used in industries of electronic, electrical and chemical components. However, there are still few studies on their impacts on civil construction, mainly on conventional concretes. Concrete has always been the subject of researches, mainly aimed at the improvement of its strength, porosity and durability. The current additions used in concrete influence on a micro scale, either acting as inert particles occupying empty spaces or as pozzolanic materials. The present study evaluated the influence of the addition of graphene oxide and colloidal silica on the chemical and mechanical properties of cementitious matrices. First, the influence of the production process on the dispersion of graphene oxide in cement pastes was evaluated. Then, the influence of graphene oxide and colloidal silica on the kinetics and mechanisms of hydration and microstructure of cement pastes was analyzed. Finally, the influence of these compounds on the development of mechanical strength in concretes at short and advanced ages was characterized. Results showed that the addition of graphene oxide and colloidal silica accelerate cement hydration reactions, promote the formation of C-S-H and densify the microstructure of cementitious composites. In addition, such compounds promoted significant gains in the compressive strength of concretes. As a result, it was possible to recommend 14% reductions in cement consumption in concretes containing these compounds, to maintain mechanical strength. The study performed may promote a significant improvement in the technology of concretes and in the sustainability of the built environment.
Nanomaterials have been widely used in industries of electronic, electrical and chemical components. However, there are still few studies on their impacts on civil construction, mainly on conventional concretes. Concrete has always been the subject of researches, mainly aimed at the improvement of its strength, porosity and durability. The current additions used in concrete influence on a micro scale, either acting as inert particles occupying empty spaces or as pozzolanic materials. The present study evaluated the influence of the addition of graphene oxide and colloidal silica on the chemical and mechanical properties of cementitious matrices. First, the influence of the production process on the dispersion of graphene oxide in cement pastes was evaluated. Then, the influence of graphene oxide and colloidal silica on the kinetics and mechanisms of hydration and microstructure of cement pastes was analyzed. Finally, the influence of these compounds on the development of mechanical strength in concretes at short and advanced ages was characterized. Results showed that the addition of graphene oxide and colloidal silica accelerate cement hydration reactions, promote the formation of C-S-H and densify the microstructure of cementitious composites. In addition, such compounds promoted significant gains in the compressive strength of concretes. As a result, it was possible to recommend 14% reductions in cement consumption in concretes containing these compounds, to maintain mechanical strength. The study performed may promote a significant improvement in the technology of concretes and in the sustainability of the built environment.
Palavras-chave
Óxido de grafeno, Sílica coloidal, Cinética de hidratação, Propriedades mecânicas