PSI - Issue 64

Pier Francesco Greco et al. / Procedia Structural Integrity 64 (2024) 1888–1895 Pier Francesco Greco/ Structural Integrity Procedia 00 (2019) 000 – 000

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5. DISCUSSION AND CONCLUSIONS The results presented in this paper show that vegetal fibers improve the maximum strain capacity of biocomposites with respect to unreinforced specimens, showing softening behavior after  peak in the flexural stress – strain curves. This softening effect is different in each sample of the same mixture to the inherent variability of natural fibers and the mixing process. The enhanced strain capacity of the biocomposites makes it suitable for strengthening applications in masonry structures, particularly historic ones Gioffrè et al.(2021). This enhancement is quantified through the fracture energy G f and the fracture energy ratio rG f , highlighting the contribution of post-peak resistance to the overall mechanical performance. Specimens reinforced with Spanish broom and hemp fibers exhibit significantly high strain energy capacity, particularly evident in three-point bending tests. The use of fibers in the composite reduces the effective cross-sectional area of the specimen, resulting in voids filled with air, which serve as weak points because of the lack of cohesion between fibers and mortar. Indeed, mortar and fibers operate at different stages of the load – displacement curve, with mortar influencing the initial stages and fibers significantly contributing after the peak load. This cohesion between the materials can be improved by using additives, organic, like rice starch Wang et al. (2022) and egg white Shanmugavel et al (2023), or inorganic, such as graphene Abbass et al. (2023), Pepi et al (2024), to enhance cohesion and maximize synergistic contributions of elements throughout testing. Work is in progress to assess the performance of biocomposites in structural strengthening of masonry structures, where the vegetal fibers are coated with nanomaterials. AKNOWLEDGMENT This work has been funded by the European Union - NextGenerationEU under the Italian Ministry of University and Research (MUR) National Innovation Ecosystem grant ECS00000041 – VITALITY - CUP J97G22000170005. These Authors are grateful to Fabbrica Tessile Bossio, Italy, for providing Spanish Broom fibers. REFERENCES Formisano, A., Dessì, E.Jr., Landolfo, R., 2017. Mechanical-physical experimental tests on lime mortars and bricks reinforced with hemp, AIP Conference Proceedings, Thessaloniki. Adam, J.P., 1988. L'arte di costruire presso i Romani: materiali e tecniche. Longanesi. Adesina, A., 2020. Recent advances in the concrete industry to reduce its carbon dioxide emissions. Environmental Challenges 1. Abbass, A., Paiva, M.C., Oliveira, D.V., Lourenço, P.B., Fangueiro, R., 2023. Graphene/polyurethane nanocomposite coatings – Enhancing the mechanical properties and environmental resistance of natural fibers for masonry retrofitting. Composites Part A 166. Andrew, R. 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