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Açaí seed ash (ASA) is a waste product from processing the açaí fruit and burning the seeds for cogeneration purposes. The present study evaluated the use of ASA from the Brazilian Amazon as partial Portland cement replacement in self-leveling mortars (SLM) for social-interest buildings. The fresh and hardened state properties of mortars were accessed with 5% and 10% ASA content, and a life cycle assessment was performed to evaluate the greenhouse gas (GHG) emissions. The maximum transport distance to enable ASA as a building material was determined by a sensitivity analysis, and specific carbon-efficiency indicators for SLM were proposed and validated. The results showed that using up to 10% ASA as cement replacement was technically and environmentally feasible since the mechanical performance was maintained and GHG emissions decreased up to 8%. The sensitivity analysis revealed that transport efficiency is crucial for ASA applications far from its production area; therefore, it should be evaluated as a regional building material. The work brings an important contribution to regional sustainable development by assessing the characteristics of a residual material and proposing the reuse of waste, reducing GHG emissions from the cement industry, and stimulating the circular bioeconomy in the Brazilian Amazon region.

The characterization of steel fiber reinforced concrete with dry consistency require greater inspection the account of the particularities in the process of mixing, molding and densification, thus this paper aims to propose a methodology combined of densification by manual and mechanical means and the mechanical characterization by the three-point flexural testin prismatic dry cast steel fiber-reinforced concrete specimen. In a qualitative way, the densification-combined methodology provided a smooth surface on the specimen appearance and a reduction of voids due to trapped air. In the flexural test we verified slip-softening and slip-hardening, respectively, to lower and higher reinforcement indexes and theoretical volumes. By the analysis of variance of the results and the database we found out that there was no significant statistical difference to the analyzed residual strength for the combination of the test method (RILEM), consistency (plastic), type (hooked end) and form (glued), when the comparison is made by quadruple association.

Resumo Os tubos de concreto com fibras de aço apresentam-se como uma variante tecnológica interessante. No estudo incipiente na localidade, o objetivo principal é o de avaliar a viabilidade técnica de tubo de concreto de armadura descontínua com fibras de aço orientadas aleatoriamente, mediante o ensaio de compressão diametral para análise do comportamento mecânico. O objetivo secundário é o de verificar a absorção de água e o teor efetivo de fibras na ponta, no meio e na bolsa do tubo. No estudo utilizaram-se as fibras de aço DRAMIX 80/60 ou 65/35, soltas ou coladas em pente, nos teores teóricos de 0,25%, 0,38% e 0,50%. Os resultados apontaram que apenas os tubos de concreto da série TCFA 80/60 - FCP nos teores efetivos de fibras de 0,36% e 0,50% e em todos os teores efetivos da série TCFA 80/60 - FS atingiram a mínima carga de ruptura e pós-fissuração estabelecida pela NBR 8890 (ABNT, 2007). Os resultados de absorção de água ficaram abaixo da máxima absorção recomendada pela NBR 8890 (ABNT, 2007) e houve maiores níveis de absorção e de teor efetivo de fibras na cadeia da ordem ponta, meio e bolsa. Ao final, mostrou-se oportuna a viabilidade técnica de tubo de concreto com fibras de aço na localidade.

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