Design for sustainability: extruded alkali activated bio-composites

• Ano de defesa: 2024
• Autor(a) principal: Sposito, Camila Cassola Assunção
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Avaliação sustentável; Bamboo leaf ash; Bio-composites; Bio-compositos; Cinza da folha de bambu; Sustainability assessment
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/74/74133/tde-30092024-135605/

The design step is essential to ensure harmony between environmental responsibility and technical performance of bio-composites. Designing for sustainability allows for reducing losses throughout its life cycle, selecting processes and raw materials that will provide the best environmental and economic performance while ensuring the technical function of the final product. Thus, through three stages, this study developed alkali-activated blast furnace slag panels reinforced by fibers for extrusion. For this purpose, the use of bamboo leaf ash (BLA) as a new source of silica for alkali suspensions as an alternative to commercial silicates was proposed. In the first stage of the study, the environmental potential of the ash was evaluated through Life Cycle Assessment (LCA), anticipating consequences from the start of BLA commercialization and the expansion of its use as an alternative material for construction. The scenarios created for this analysis showed the sustainable potential of the ash, especially concerning the mitigation of the climate change category due to the high amounts of biogenic carbon associated with the bamboo cultivation life cycle. The second stage of the research consisted of determining the optimal value for the SiO2/Na2O molar ratio (ε) for three AAM matrix designs based on the choice of the activator: i) BLA suspension and NaOH (NH/BLA); ii) NaOH solution (NH); iii) Na2SiO3 solution in NaOH (NH/SS). The choice was conducted by an ecodesign method based on the environmental and functional performance of the matrix. The designs NH/BLA with ε = 1.0 and 1.5 obtained higher ecoefficiency (a \"win-win\" solution). Finally, in the third stage of the work, these two matrices were selected for the development of ventilated facade panels, extruded and reinforced by PVA fiber. The MARS-SC method was chosen to support the multicriteria decision analysis of the best sustainable solution, according to thirteen indicators divided according to the environmental, functional, and economic spheres of the product. Ultimately, the panel activated by suspension of BLA in NaOH with ε = 1.5 received the highest sustainable score (1.0). The use of BLA also positively influenced the functional properties of bending strength, toughness, Young\'s modulus, and thermal conductivity.