Durability assessment of MgO-based fiber cement reinforced with lignocellulosic fibers and cured in a CO2-rich atmosphere

Azevedo, A. G. S.; Baltazar, L.; Faria, P.; Savastano, H.

http://hdl.handle.net/10362/184112

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This study investigates the durability and performance of fiber cement composites produced from magnesium oxysulfate (MOS) matrices reinforced with lignocellulosic fibers, subjected to accelerated carbonation. The composites underwent mechanical, physical, and chemical characterization through flexural strength tests, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) after various aging cycles. Durability was assessed via freeze-thaw, soak-and-dry, and UV exposure tests. Carbonation led to a reduction in mechanical strength, which is attributed to the reaction of CO2 with phase 5-1-7, a key component responsible for strength development. The formation of new carbonation products, confirmed by TGA and SEM, modified the physical properties of the composites. The changes in physical properties clearly demonstrate that accelerated carbonation promoted the formation of Hydrated Magnesium Carbonates (HMCs), which precipitated in voids, thereby increasing the density of the fiber cements. XRD analysis showed a reduction in the phase 5-1-7 peak intensity following CO2 exposure, corroborating the carbonation process. These results contribute to optimizing curing processes and durability treatments, enhancing the applicability of MOS-based composites in construction, particularly for prefabricated panels and non-structural walling systems exposed to different weather conditions.

Descrição

Funding Information: To the São Paulo Research Foundation (FAPESP) - Processes: 2024/02445-4, 2021/04780-7, 2022/07179-5, and 2014/50948-3. To the CNPQ- Processes: 422701/2021-1 and 402980/2022-0. The Portuguese Foundation for Science and Technology for funding research units CERIS (UIDB/04625/2020) at the NOVA University of Lisbon and the University of Minho. Publisher Copyright: © 2025

Palavras-chave

Accelerated carbonation Durability Fiber cement boards MOS Civil and Structural Engineering Architecture Building and Construction Safety, Risk, Reliability and Quality Mechanics of Materials