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.
Sustainable cements are an important alternative to reduce the environmental impact of the cement industry by lowering the clinker-to-cement ratio with supplementary cementitious materials. In this respect, the present study aimed to evaluate the influence of partial clinker replacement by sugarcane bagasse ash (SCBA) and limestone filler (LF) on the mechanical and durability performance of mortars. Four blended Portland cements were produced with binary and ternary mixes of clinker, SCBA, and LF. An ordinary cement was also produced for comparison purposes. All five cements were characterized and applied in mortars in order to assess compressive strength and water absorption. Next, 28-day specimens were immersed in a sulfuric acid solution for 56 days to investigate deterioration using mass loss, length variation, water absorption, and compressive strength tests. In general, the combination of SCBA and LF produced more sustainable cements with suitable properties, as SCBA improved the mechanical behavior, while LF improved the durability performance of mortars. In this context, ternary mixes with 14% SCBA and 14% LF are indicated for mechanical uses, while 7% SCBA and 14% LF are recommended for durability purposes, as both maintained the respective properties of the reference cement.
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