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A escassez de recursos naturais e os impactes ambientais causados pela indústria da construção civil têm motivado o desenvolvimento de novos materiais e práticas integradas às três vertentes da sustentabilidade: ambiental, social e económica. A mudança da economia linear atual, com base no processo de extrair-transformar-usar-rejeitar, para um processo circular é inevitável, neste novo modelo são preservados os recursos que já estão em uso e mantido seu valor económico mais elevado pelo maior tempo possível. A economia circular é a oportunidade da indústria da construção civil se reinventar, atingindo melhores níveis de eficiência e produtividade, além de reduzir significativamente a dependência de combustíveis fósseis, uso de recursos e geração de resíduos. Particularmente as estruturas de betão armado possuem elevado valor energético por utilizarem em larga escala o cimento e poderiam absorver resíduos de outras indústrias, seja na sua composição ou no seu sistema de montagem em obra (cimbres e cofragens), como é o caso do presente trabalho que propõe a utilização de painéis a partir de compósitos de matriz termoplástica reciclável para sistemas cofrantes. Para tal, produziu-se pré-impregnados por um processo inovador de deposição de polímero em pó (PET reciclado) e seguidamente transformou-se em perfis compósitos por pultrusão. Este processo de fabrico deu origem a perfis compósitos que permaneceram em contato com argamassa de cimento e óleo descofrante durante o período de cura, simulando as duas condições em que as cofragens normalmente são solicitadas. Em diferentes períodos de cura da argamassa, os provetes foram ensaiados a flexão, testando assim a influência do meio altamente alcalino nas propriedades mecânicas do compósito. Os resultados apresentaram elevados valores de módulo de elasticidade e excelente resistência para o uso em cofragens, além de se concluir que o meio alcalino não afetou o desempenho dos perfis compósitos.
The scarcity of natural resources and the environmental impacts caused by the construction industry have motivated the development of new materials and practices integrated to the three aspects of sustainability: environmental, social and economic. The change from the current linear economy, based on the process of extract-transform-use-reject, to a circular process is inevitable, in this new model are preserved resources that are already in use and maintained their highest economic value for as long as possible. Circular economics is the opportunity for the construction industry to reinvent itself, achieving better levels of efficiency and productivity, and significantly reducing dependence on fossil fuels, resource use and waste generation. In particular, reinforced concrete structures have a high energy value because they use cement in large scale and could absorb waste from other industries, either in their composition or in their on-site assembly system (formworks). Therefore, the present work proposes the use of panels from recyclable thermoplastic matrix composites for cofrant systems. For this, prepregs were produced by an innovative powder deposition process (recycled PET) and then made into composite profiles by pultrusion. This manufacturing process gave rise to composite profiles that remained in contact with cement mortar and desorbing oil during the curing period, simulating the two conditions in which the formers are normally required. At different cure times of the mortar, the test specimens were flexed, thus testing the influence of the highly alkaline medium on the mechanical properties of the composite. The results presented high values of modulus of elasticity and excellent resistance for use in formwork, in addition to the conclusion that the alkaline medium did not affect the performance of the composite profiles.
The scarcity of natural resources and the environmental impacts caused by the construction industry have motivated the development of new materials and practices integrated to the three aspects of sustainability: environmental, social and economic. The change from the current linear economy, based on the process of extract-transform-use-reject, to a circular process is inevitable, in this new model are preserved resources that are already in use and maintained their highest economic value for as long as possible. Circular economics is the opportunity for the construction industry to reinvent itself, achieving better levels of efficiency and productivity, and significantly reducing dependence on fossil fuels, resource use and waste generation. In particular, reinforced concrete structures have a high energy value because they use cement in large scale and could absorb waste from other industries, either in their composition or in their on-site assembly system (formworks). Therefore, the present work proposes the use of panels from recyclable thermoplastic matrix composites for cofrant systems. For this, prepregs were produced by an innovative powder deposition process (recycled PET) and then made into composite profiles by pultrusion. This manufacturing process gave rise to composite profiles that remained in contact with cement mortar and desorbing oil during the curing period, simulating the two conditions in which the formers are normally required. At different cure times of the mortar, the test specimens were flexed, thus testing the influence of the highly alkaline medium on the mechanical properties of the composite. The results presented high values of modulus of elasticity and excellent resistance for use in formwork, in addition to the conclusion that the alkaline medium did not affect the performance of the composite profiles.
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Keywords
Economia Circular Cofragens Painéis Compósitos Pultrusão Circular Economy Formworks Composite Panels Pultrusion