PSI - Issue 68

ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Structural Integrity Procedia 00 (2025) 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 68 (2025) 259–265

European Conference on Fracture 2024 Compressive strength of high-strength concrete modified with synthetic fibers at elevated temperatures Rami Hawileh a, *, Ahmed Selim a , Maha Assad a , Jamal Abdalla a , Abdulrahman Mohamed a , Abdulrahman Madkour a a American University of Sharjah, Department of Civil Engineering, P.O. Box 26666, Sharjah, United Arab Emirates Abstract High-strength concrete (HSC) demonstrates exceptional performance at room temperature, including high compressive and flexural strengths, coupled with remarkable durability. However, it exhibits poor performance under high temperatures due to its dense microstructure that leads to increased risk of explosive spalling. Studies also showed that HSC has higher degradation in its mechanical properties under elevated temperatures compared to normal-strength concrete. Therefore, synthetic fibers, such as polypropylene (PP) fibers are added to the concrete mix to reduce the extent of spalling and increase its fire resistance. This study aims to investigate the degradation in compressive strength properties of HSC, made of local materials in the UAE, with variable composition of PP fibers and steel fibers. Two mix designs were developed in this study. The first mix had 1% steel fibers only, and the second mix consisted of 1% steel fibers with 0.1% PP fiber. Results showed that specimens with steel fibers only exhibited the highest compressive strength at room temperature with the lowest residual The second mix provided comparable strengths to the first mix and acceptable strength degradation. Thus, it can be concluded that the design of the HSC mix can be utilized with the inclusion of synthetic fibers to enhance its fire resistance whilst maintaining its strength. Finally, material models for the degradation in the compressive strength of HSC are developed for the two mixes, respectively. © 2025 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) European Conference on Fracture 2024 Compressive strength of high-strength concrete modified with synthetic fibers at elevated temperatures Rami Hawileh a, *, Ahmed Selim a , Maha Assad a , Jamal Abdalla a , Abdulrahman Mohamed a , Abdulrahman Madkour a a American University of Sharjah, Department of Civil Engineering, P.O. Box 26666, Sharjah, United Arab Emirates Abstract High-strength concrete (HSC) demonstrates exceptional performance at room temperature, including high compressive and flexural strengths, coupled with remarkable durability. However, it exhibits poor performance under high temperatures due to its dense microstructure that leads to increased risk of explosive spalling. Studies also showed that HSC has higher degradation in its mechanical properties under elevated temperatures compared to normal-strength concrete. Therefore, synthetic fibers, such as polypropylene (PP) fibers are added to the concrete mix to reduce the extent of spalling and increase its fire resistance. This study aims to investigate the degradation in compressive strength properties of HSC, made of local materials in the UAE, with variable composition of PP fibers and steel fibers. Two mix designs were developed in this study. The first mix had 1% steel fibers only, and the second mix consisted of 1% steel fibers with 0.1% PP fiber. Results showed that specimens with steel fibers only exhibited the highest compressive strength at room temperature with the lowest residual The second mix provided comparable strengths to the first mix and acceptable strength degradation. Thus, it can be concluded that the design of the HSC mix can be utilized with the inclusion of synthetic fibers to enhance its fire resistance whilst maintaining its strength. Finally, material models for the degradation in the compressive strength of HSC are developed for the two mixes, respectively. © 2025 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 ECF24 organizers Keywords: Type your keywords here, separated by semicolons ; 1. Introduction High-strength concrete (HSC) offers remarkable improvements in structural performance, particularly in terms of load-bearing capacity and durability (Assad et al., (2022); Mahmoud et al., (2021)). However, the main drawback of © 2025 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 ECF24 organizers Peer-review under responsibility of ECF24 organizers Keywords: Type your keywords here, separated by semicolons ; 1. Introduction High-strength concrete (HSC) offers remarkable improvements in structural performance, particularly in terms of load-bearing capacity and durability (Assad et al., (2022); Mahmoud et al., (2021)). However, the main drawback of

* Corresponding author. Tel.: +971 6 515 2496; fax: +971 6 515 2979. E-mail address: rhaweeleh@aus.edu * Corresponding author. Tel.: +971 6 515 2496; fax: +971 6 515 2979. E-mail address: rhaweeleh@aus.edu

2452-3216 © 2025 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 ECF24 organizers 2452-3216 © 2025 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 ECF24 organizers

2452-3216 © 2025 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 ECF24 organizers 10.1016/j.prostr.2025.06.051