Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropes

Exposure of reinforced concrete (RC) structures to elevated temperatures results in significant degradation of their mechanical properties and overall structural integrity, necessitating the development of effective repair strategies to restore their load-bearing capacity and long-term durability. T...

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Main Authors: Ahmed Ashteyat, Mousa Shhabat, Ibrahim Al-Hazmi
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Composites Part C: Open Access
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Online Access:http://www.sciencedirect.com/science/article/pii/S2666682025000349
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author Ahmed Ashteyat
Mousa Shhabat
Ibrahim Al-Hazmi
author_facet Ahmed Ashteyat
Mousa Shhabat
Ibrahim Al-Hazmi
author_sort Ahmed Ashteyat
collection DOAJ
description Exposure of reinforced concrete (RC) structures to elevated temperatures results in significant degradation of their mechanical properties and overall structural integrity, necessitating the development of effective repair strategies to restore their load-bearing capacity and long-term durability. This study introduces a novel approach through both experimental and theoretical investigations into the efficacy of using Near-Surface Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) ropes to repair two-way high-strength concrete (HSC) solid slabs subjected to elevated temperatures of 600 °C for a duration of 3 h. A total of eight slabs, each measuring 1050 × 1050 × 70 mm, were tested, comprising two normal-strength concrete (NSC) slabs and six HSC slabs. The study examined three primary variables: the number of CFRP ropes (2 or 3), their orientation angles (0° or 45°), and their configuration patterns (radial star or concentric squares). The key performance indicators evaluated included load capacity, failure modes, stiffness, and ductility. The experimental results indicated that the NSM-CFRP rope repairing technique significantly enhanced the structural performance of heat-damaged slabs. Load capacity improved by 12 % to 35 %, stiffness by 260 % to 343 %, and ductility by 127 % to 324 % when compared to unstrengthened slabs. Notably, the configurations of one rope in a radial star pattern around the column (R-SR) and three ropes arranged in concentric squares at a 45° angle (3R-CS 45°) demonstrated the highest recovery efficiencies, restoring the pre-fire load capacity by 10 % and 1 %, respectively. Theoretical analysis revealed that the models by El-Gamal et al. and Ospina et al. provided close alignment with the experimental findings, with average experimental-to-theoretical ratios of 1.09 and 1.12, respectively. In contrast, the ACI 440.2R-22 model was more conservative, yielding a ratio of 1.22, while the JSCE-97 model significantly overestimated the punching shear capacity, exhibiting the least accuracy among the models analyzed, with a mean ratio of 1.81 and a standard deviation of 0.126. The findings of this research underscore the viability of NSM-CFRP ropes as an efficient and economical method for restoring heat-damaged concrete slabs. This approach provides a flexible repair solution that requires minimal disruption, positioning it as an ideal option for industrial and infrastructure rehabilitation projects.
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spelling doaj-art-9e387136cc5b4f0ba51949f47c4de69f2025-08-20T03:10:30ZengElsevierComposites Part C: Open Access2666-68202025-07-011710059010.1016/j.jcomc.2025.100590Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropesAhmed Ashteyat0Mousa Shhabat1Ibrahim Al-Hazmi2Department of Civil Engineering, College of Engineering in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi Arabia; Faculty of Engineering, Department of Civil Engineering, The University of Jordan, Amman 11942, Jordan; Corresponding author at: Faculty of Engineering, Department of Civil Engineering, The University of Jordan, Amman 11942, Jordan.Department of Civil Engineering, College of Engineering in Al-Kharj, Prince Sattam Bin Abdulaziz University, Al-Kharj 11942, Saudi ArabiaDepartment of Civil Engineering, The University of Akron, Akron, OH 44325, USAExposure of reinforced concrete (RC) structures to elevated temperatures results in significant degradation of their mechanical properties and overall structural integrity, necessitating the development of effective repair strategies to restore their load-bearing capacity and long-term durability. This study introduces a novel approach through both experimental and theoretical investigations into the efficacy of using Near-Surface Mounted (NSM) Carbon Fiber Reinforced Polymer (CFRP) ropes to repair two-way high-strength concrete (HSC) solid slabs subjected to elevated temperatures of 600 °C for a duration of 3 h. A total of eight slabs, each measuring 1050 × 1050 × 70 mm, were tested, comprising two normal-strength concrete (NSC) slabs and six HSC slabs. The study examined three primary variables: the number of CFRP ropes (2 or 3), their orientation angles (0° or 45°), and their configuration patterns (radial star or concentric squares). The key performance indicators evaluated included load capacity, failure modes, stiffness, and ductility. The experimental results indicated that the NSM-CFRP rope repairing technique significantly enhanced the structural performance of heat-damaged slabs. Load capacity improved by 12 % to 35 %, stiffness by 260 % to 343 %, and ductility by 127 % to 324 % when compared to unstrengthened slabs. Notably, the configurations of one rope in a radial star pattern around the column (R-SR) and three ropes arranged in concentric squares at a 45° angle (3R-CS 45°) demonstrated the highest recovery efficiencies, restoring the pre-fire load capacity by 10 % and 1 %, respectively. Theoretical analysis revealed that the models by El-Gamal et al. and Ospina et al. provided close alignment with the experimental findings, with average experimental-to-theoretical ratios of 1.09 and 1.12, respectively. In contrast, the ACI 440.2R-22 model was more conservative, yielding a ratio of 1.22, while the JSCE-97 model significantly overestimated the punching shear capacity, exhibiting the least accuracy among the models analyzed, with a mean ratio of 1.81 and a standard deviation of 0.126. The findings of this research underscore the viability of NSM-CFRP ropes as an efficient and economical method for restoring heat-damaged concrete slabs. This approach provides a flexible repair solution that requires minimal disruption, positioning it as an ideal option for industrial and infrastructure rehabilitation projects.http://www.sciencedirect.com/science/article/pii/S2666682025000349Two-way slabHigh strength concreteHigh temperatureCfrp-ropeNear-surface mountedPrediction models
spellingShingle Ahmed Ashteyat
Mousa Shhabat
Ibrahim Al-Hazmi
Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropes
Composites Part C: Open Access
Two-way slab
High strength concrete
High temperature
Cfrp-rope
Near-surface mounted
Prediction models
title Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropes
title_full Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropes
title_fullStr Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropes
title_full_unstemmed Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropes
title_short Repairing high-strength concrete two-way solid slabs exposed to elevated temperature using NSM-CFRP ropes
title_sort repairing high strength concrete two way solid slabs exposed to elevated temperature using nsm cfrp ropes
topic Two-way slab
High strength concrete
High temperature
Cfrp-rope
Near-surface mounted
Prediction models
url http://www.sciencedirect.com/science/article/pii/S2666682025000349
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