Estudo do potencial da cinza de folha de bambu para sua utilização como material pozolânico e sustentável em matrizes cimentantes
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Data
2019-02-18
Autores
Moraes, Maria Júlia Bassan de
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Universidade Estadual Paulista (Unesp)
Resumo
O contexto mundial de preocupação em relação ao meio-ambiente, seu uso desenfreado e a emissão dos gases estufa, principalmente a emissão de dióxido de carbono destacou a importância da pesquisa para se buscar novas alternativas sustentáveis nos meios de produção, dentre eles se encaixa a indústria do cimento Portland. A proposta deste estudo é uma nova alternativa sustentável para a construção civil, estudando a cinza de folha de bambu (CFB) como material pozolânico para ser utilizado como substituição parcial do cimento Portland. A cinza de folha de bambu foi produzida através de um processo de autocombustão sem temperatura controlada, e foi caracterizada física e quimicamente através dos ensaios de Fluorescência de Raio – X (FRX), determinação do teor de sílica amorfa, Difratometria de Raio – X (DRX), Granulometria a Laser, Microscopia Eletrônica de Varredura por Emissão de Campo (FESEM), Espectroscopia de Infravermelho por Transformada de Fourier (FTIR) e Analise Termogravimétrica (TGA). Sua reatividade foi analisada através dos ensaios de condutividade elétrica e pH, ensaio de Frattini e pastas de Cal/CFB e Cimento/CFB, as quais foram submetidas aos ensaios de FTIR, TGA e FESEM. Para avaliar sua influência na argamassa no estado fresco e endurecido, foram realizados os ensaios de índice de consistência e o ensaio de resistência à compressão, comparando-se as argamassas com substituição parcial do cimento à uma argamassa controle, sem adição mineral. Já a influência da cinza na durabilidade foi analisada através da porosimetria por intrusão de mercúrio e da capacidade de neutralização ácida. Através dos resultados obtidos, concluiu-se que a CFB estudada é formada principalmente por sílica (74,23%), %), sendo que 92,33% desse óxido se trata da sílica amorfa. O tempo de moagem ótimo da cinza é de 50 minutos. A fluidez da matriz cimentícia é prejudicada com a adição da cinza, porém continua aceitável. A CFB foi classificada como altamente reativa, o que refletiu na sua influência no comportamento mecânico e na durabilidade das matrizes cimentantes. Todas as argamassas com substituição parcial apresentaram resistência à compressão similar a argamassa controle com apenas 3 dias de cura e para as seguintes idades. Na análise de porosimetria por intrusão de mercúrio (PIM), pastas com substituições com teores de 20% e 30% de CFB apresentaram maior tortuosidade ou menos poros conectados do que a pasta de controle. Dessa forma, o método de autocombustão provou ser bem-sucedido e a CFB trata-se de uma alternativa adequada e sustentável para ser utilizada como substituição parcial do cimento Portland em matrizes cimentantes.
The global context of concern for the environment, its unrestrained use and emission of greenhouse gases, especially the emission of carbon dioxide, highlighted the importance of research to find new sustainable alternatives in the means of production, among them, the Portland cement industry. The proposal of this study is a new sustainable alternative for civil construction, studying bamboo leaf ash (BLA) as pozzolanic material to be used as partial replacement of Portland cement. The bamboo leaf ash was produced by a process of autocombustion without temperature control, and was characterized physically and chemically by means of X - Ray Fluorescence (FRX), determination of the amorphous silica content, X - Ray Diffractometry (XRD), Laser Granulometry, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The reactivity analysis was carried out by means of electrical conductivity and pH measurements, Frattini analysis and calcium hydroxide / CFB and Cement / CFB pastes, which were assessed by FTIR, TGA and FESEM analysis. In order to evaluate its influence on the mortar in the fresh and hardened states, the tests of consistency index and compressive strength were carried out, comparing mortars with cement partial replacement with a control mortar, without mineral addition. The influence of the ash on durability was analyzed by means of mercury intrusion porosimetry analysis (MIP) and acid neutralization capacity. The results obtained showed that the studied CFB is mainly composed of silica (74,23%), 92,33% of which are amorphous silica. The optimal milling time of the ash is 50 minutes. The fluidity of the cementitious matrix is impaired with the addition of ash but remains acceptable. The CFB was classified as highly reactive, which reflected in its influence on the mechanical behavior and durability of the cementitious matrices. All the mortars containing CFB presented very similar compressive strength to a control mortar after only 3 days of curing and at the following tested curing ages: 7, 28 and 90 days. In the mercury intrusion porosimetry analysis, the pastes with 20 and 30% CFB content presented higher tortuosity or fewer connected pores than the control paste. Thus, the auto-combustion method proved to be successful and CFB is a suitable and sustainable alternative for OPC partial replacement in cementitious matrices.
The global context of concern for the environment, its unrestrained use and emission of greenhouse gases, especially the emission of carbon dioxide, highlighted the importance of research to find new sustainable alternatives in the means of production, among them, the Portland cement industry. The proposal of this study is a new sustainable alternative for civil construction, studying bamboo leaf ash (BLA) as pozzolanic material to be used as partial replacement of Portland cement. The bamboo leaf ash was produced by a process of autocombustion without temperature control, and was characterized physically and chemically by means of X - Ray Fluorescence (FRX), determination of the amorphous silica content, X - Ray Diffractometry (XRD), Laser Granulometry, Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA). The reactivity analysis was carried out by means of electrical conductivity and pH measurements, Frattini analysis and calcium hydroxide / CFB and Cement / CFB pastes, which were assessed by FTIR, TGA and FESEM analysis. In order to evaluate its influence on the mortar in the fresh and hardened states, the tests of consistency index and compressive strength were carried out, comparing mortars with cement partial replacement with a control mortar, without mineral addition. The influence of the ash on durability was analyzed by means of mercury intrusion porosimetry analysis (MIP) and acid neutralization capacity. The results obtained showed that the studied CFB is mainly composed of silica (74,23%), 92,33% of which are amorphous silica. The optimal milling time of the ash is 50 minutes. The fluidity of the cementitious matrix is impaired with the addition of ash but remains acceptable. The CFB was classified as highly reactive, which reflected in its influence on the mechanical behavior and durability of the cementitious matrices. All the mortars containing CFB presented very similar compressive strength to a control mortar after only 3 days of curing and at the following tested curing ages: 7, 28 and 90 days. In the mercury intrusion porosimetry analysis, the pastes with 20 and 30% CFB content presented higher tortuosity or fewer connected pores than the control paste. Thus, the auto-combustion method proved to be successful and CFB is a suitable and sustainable alternative for OPC partial replacement in cementitious matrices.
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Palavras-chave
Cinza de folha de bambu, Material pozolânico, Sustentabilidade, Caracterização, Reatividade, Durabilidade, Comportamento mecânico, Bamboo leaf ash, Pozzolanic material, Sustainability, Characterization, Reactivity, Durability, Mechanical behavior