PSI - Issue 64

Omid Hassanshahi et al. / Procedia Structural Integrity 64 (2024) 81–88 Hassanshahi et al. / Durability of GFRP Composites Produced by Pultrusion under Thermal Environments

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40 °C was obtained). Flexural strength retention varied between GFRP_UP and GFRP_VE composites, with GFRP_UP generally showing higher overall retention (a maximum 5% increase was registered). In-plane shear strength retention, however, displayed similar variation trends for both composites, indicating good performance under thermal cycling (a maximum reduction of 11% was observed). Overall, these initial findings underscore the complex interplay between environmental conditions, matrix type, and mechanical performance of GFRP composites, providing valuable insights into their durability and laying the foundation for future research in this area. However, this study is limited by its focus on accelerated laboratory ageing tests, necessitating further investigation into various accelerated and natural ageing conditions and long-term effects. Ongoing research is necessary to deepen the understanding of these phenomena, enabling the development of predictive models and possible improvements in design guidelines for their reliable use in civil engineering structural applications. Acknowledgements This work was carried out in the scope of the project DURABLE-FRP (PTDC/ECI-EGC/4609/2020, doi:10.54499/PTDC/ECI-EGC/4609/2020) funded by national funds financed by the European Fund of the Regional Development (FEDER) through the Operational Program for Competitiveness and Internationalization (POCI) and the Lisbon Regional Operational Program. It was also partly financed by FCT/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020 (doi:10.54499/PTDC/ECI-EGC/4609/2020), and under the Associate Laboratory Advanced Production and Intelligent Systems ARISE under reference LA/P/0112/2020. The funding provided by FCT to the CERIS research unit, through project UIDB/04625/2020 (doi.org/10.54499/UIDB/04625/2020), is also gratefully acknowledged. References ASTM D5379-19. Standard test method for shear properties of composite materials by the V-notched beam method. ASTM D7792/D7792M-15. Standard practice for freeze/thaw conditioning of pultruded fibre reinforced polymer (FRP) composites used in structural designs. Bazli, M., Ashrafi, H. and Oskouei, A.V., 2016. Effect of harsh environments on mechanical properties of GFRP pultruded profiles. Composites Part B: Engineering, 99, pp. 203-215. CEN/TS 19101:2022. Design of fibre-polymer composite structures. European Committee for Standardization, CEN/TC 250. Grammatikos, S.A., Jones, R.G., Evernden, M. and Correia, J.R., 2016. Thermal cycling effects on the durability of a pultruded GFRP material for off-shore civil engineering structures. Composite Structures , 153 , pp.297-310. ISO 14125:1998. Fibre-reinforced plastic composites. Determination of flexural properties. ISO 14126:1999. Fibre-reinforced plastic composites. Determination of compressive properties in the in-plane direction. ISO 14130:1997. Fibre-reinforced plastic composites. Determination of apparent interlaminar shear strength by short-beam method. ISO 527-4:2021. Plastics — Determination of tensile properties. Part 4: Test conditions for isotropic and orthotropic fibre-reinforced plastic composites. ISO 6721-5:2019. Plastics — Determination of dynamic mechanical properties. Part 5: Flexural vibration. Non-resonance method. Karbhari, V.M. (2007). Durability of composites for civil structural applications. Woodhead Publishing Limited. Karbhari, V.M., Chin, J.W., Hunston, D., Benmokrane, B., Juska, T., Morgan, R., Lesko, J.J., Sorathia, U., Reynaud, D. (2003). Durability gap analysis for fibre-reinforced polymer composites in civil infrastructure. Journal of Composites for Construction . 7(3), 238-247. Nguyen, K.Q., Cousin, P., Robert, M., Elkoun, S. and Benmokrane, B., 2024. Ageing and integrity studies of GFRP composites for civil engineering applications. In Ageing and Durability of FRP Composites and Nanocomposites (pp. 219-238). Woodhead Publishing. Sousa, J.M., Correia, J.R., Cabral-Fonseca, S. and Diogo, A.C., 2014. Effects of thermal cycles on the mechanical response of pultruded GFRP profiles used in civil engineering applications. Composite Structures , 116 , pp. 720-731. Sun, W., Vassilopoulos, A.P., Keller, T. Effect of temperature on kinking failure mode of non slender glass fibre-reinforced polymer specimens. Composite Structures , 133, pp. 178-190. Vieira, P.S.C., de Souza, F.S., Cardoso, D.C.T., Vieira, J.D. and de Andrade Silva, F., 2020. Influence of moderate/high temperatures on the residual flexural behavior of pultruded GFRP. Composites Part B: Engineering , 200 , p. 108335. Yang, S., Liu, W., Fang, Y. and Huo, R., 2019. Influence of hygrothermal ageing on the durability and interfacial performance of pultruded glass fibre-reinforced polymer composites. Journal of Materials Science , 54 (3), pp. 2102-2121.