PSI - Issue 64

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Structural Integrity Procedia 00 (2023) 000 – 000

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Procedia Structural Integrity 64 (2024) 1832–1839

SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Repair and strengthening of existing structures using FRP composites externally-bonded with toughened epoxy adhesives Angelo Savio Calabrese a , Massimiliano Bocciarelli a , Tommaso D’Antino a , Tommaso Papa a , Pierluigi Colombi a, * a Department of Architecture, Built Environment and Construction Engineering, Politecnico di Milano, Milan 20133, Italy Abstract This literature review investigates the efficacy of toughened epoxy adhesives for structural repair and strengthening of existing structures with FRP composites. Highlighting the limitations of traditional epoxy adhesives, such as susceptibility to fatigue loading and impact actions, the study explores the potential of toughened formulations to mitigate fracture propagation issues. Through the incorporation of additional phases like rubber particles or nanomaterials, toughened adhesives offer increased fracture toughness and improved structural performance. However, this could also lead to trade-offs, including potential reductions in mechanical properties, glass transition temperature reduction and possible health and environmental concerns. This study presents an overview of the main toughening mechanisms occurring in modified epoxy resins. Two toughening techniques are described and discussed, namely the rubber-toughening and nanomaterial-toughening. The study further investigates the effects of the use of toughened adhesives in externally-bonded FRP strengthening/repair applications, involving both steel and concrete substrates. Eventually, the difference in bond-slip behavior of toughened and traditional adhesives is described, with reference to currently available literature studies on the topic. This review paper shed light on the promising advantages of using toughened epoxy adhesives in FRP applications, in terms of higher bond and strain capacity and enhanced bond transfer mechanisms between composite and substrate, if compared to traditional adhesives. © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers © 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

* Corresponding author. Tel.: +39-022-399-4280; fax: +39-022-399-4220. E-mail address: pierluigi.colombi@polimi.it

2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers 10.1016/j.prostr.2024.09.234