PSI - Issue 64

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

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 64 (2024) 1360–1368

SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Fly Ash Geopolymer Paste for NSM CFRP Application Under Elevated Temperatures: Material Development SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Fly Ash Geopolymer Paste for NSM CFRP Application Under Elevated Temperatures: Material Development

Hamzeh Shdeifat a * , Robin Kalfat a , Riadh Al Mihaidi a a, School of Engineering, Swinburne University of Technology, Melbourne, 3122, Australia Hamzeh Shdeifat a * , Robin Kalfat a , Riadh Al Mihaidi a a, School of Engineering, Swinburne University of Technology, Melbourne, 3122, Australia

Abstract Strengthening of reinforced concrete (RC) structures using near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) technique is exhibited as effective and promising technology. However, having epoxy adhesive as the binding agent between the CFRP laminate and concrete substrate presents a serious drawback due to its low glass transition temperature (GT), which when exceeded, the epoxy adhesive loses its mechanical strength. This study focuses on optimizing a fly ash (FA) geopolymer adhesive as an alternative to epoxy. Several mixes with different constituent proportions have been investigated for their residual compressive strength and volume change at different firing periods. One mix was quenched in water to introduce and evaluate thermal shock impacts. The results demonstrate that the highest compressive strength at ambient temperature and the lowest volume change at elevated temperatures were recorded by the mix with the lowest SiO 2 /K 2 O. Mixes with higher activator alkali content achieved the highest residual compressive strength and exhibited expansion at elevated temperatures. Furthermore, the geopolymer exposed to water quenching recorded a slight decrease in both residual compressive strength and volume in comparison with samples cooled naturally. Overall, the findings suggest that employing potassium-based geopolymers in NSM CFRP applications could offer significant improvements in terms of advancing thermomechanical performance. © 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 Keywords: Epoxy resin, geopolymer adhesive, NSM CFRP Strengthening, alkali-activated fly ash/slag, potassium-based activator Abstract Strengthening of reinforced concrete (RC) structures using near surface mounted (NSM) carbon fiber reinforced polymer (CFRP) technique is exhibited as effective and promising technology. However, having epoxy adhesive as the binding agent between the CFRP laminate and concrete substrate presents a serious drawback due to its low glass transition temperature (GT), which when exceeded, the epoxy adhesive loses its mechanical strength. This study focuses on optimizing a fly ash (FA) geopolymer adhesive as an alternative to epoxy. Several mixes with different constituent proportions have been investigated for their residual compressive strength and volume change at different firing periods. One mix was quenched in water to introduce and evaluate thermal shock impacts. The results demonstrate that the highest compressive strength at ambient temperature and the lowest volume change at elevated temperatures were recorded by the mix with the lowest SiO 2 /K 2 O. Mixes with higher activator alkali content achieved the highest residual compressive strength and exhibited expansion at elevated temperatures. Furthermore, the geopolymer exposed to water quenching recorded a slight decrease in both residual compressive strength and volume in comparison with samples cooled naturally. Overall, the findings suggest that employing potassium-based geopolymers in NSM CFRP applications could offer significant improvements in terms of advancing thermomechanical performance. © 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 Keywords: Epoxy resin, geopolymer adhesive, NSM CFRP Strengthening, alkali-activated fly ash/slag, potassium-based activator © 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.: +613-9214-3421 E-mail address: hshdeifat@swin.edu.au * Corresponding author. Tel.: +613-9214-3421 E-mail address: hshdeifat@swin.edu.au

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

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