Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposure
Ultra-high-performance concrete (UHPC) is renowned for its superior mechanical and durability characteristics. While many studies have focused on thermal effects such as explosive spalling and the compressive and flexural properties of UHPC, there is limited research on its residual uniaxial tensile...
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Elsevier
2025-07-01
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| Series: | Case Studies in Construction Materials |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2214509524013251 |
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| author | Sohit Agrawal Erika Yulianti Mugahed Amran Chung-Chan Hung |
| author_facet | Sohit Agrawal Erika Yulianti Mugahed Amran Chung-Chan Hung |
| author_sort | Sohit Agrawal |
| collection | DOAJ |
| description | Ultra-high-performance concrete (UHPC) is renowned for its superior mechanical and durability characteristics. While many studies have focused on thermal effects such as explosive spalling and the compressive and flexural properties of UHPC, there is limited research on its residual uniaxial tensile behavior. Moreover, variations in the heating rates adopted across different studies further complicate the ability to formulate broad, generalizable conclusions. This study aims to address these gaps by systematically investigating the thermal behavior of unconfined steel-fiber reinforced UHPC in line with the ASTM E119 standard fire exposure. Methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and mechanical and durability testing were employed to comprehensively assess UHPC's post-fire performance at ambient temperature. Results revealed that by 200 ˚C, portlandite began converting into calcium oxide and water vapor. Simultaneously, levels of calcium silicate hydrate and calcium carbonate rose, indicating continued hydration at elevated temperatures. SEM imaging exposed significant microstructural issues at 300 ˚C, including debonding between fibers and the matrix, alongside microcracking and degradation at the aggregate-cement paste interface. This deterioration correlated with a significant increase in porosity, permeability, and water absorption, particularly at 300 ˚C. Although compressive strength continued to rise, peaking at 300 ˚C, tensile properties only showed optimal performance up to 200 ˚C before declining, demonstrating a differential impact of temperature on UHPC’s mechanical behavior. Despite this, UHPC displayed tensile strain-hardening behavior up to 300 ˚C, with post-peak strain increasing from 0.2 % at ambient temperature to 0.66 % at 300 ˚C. Nevertheless, a 1.5 % volume fraction of steel fibers proved ineffective in restraining explosive failure at temperatures exceeding 300 ˚C. |
| format | Article |
| id | doaj-art-f5593e5e213b447ea21b04d7f0383af1 |
| institution | Kabale University |
| issn | 2214-5095 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Case Studies in Construction Materials |
| spelling | doaj-art-f5593e5e213b447ea21b04d7f0383af12025-01-11T06:41:25ZengElsevierCase Studies in Construction Materials2214-50952025-07-0122e04173Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposureSohit Agrawal0Erika Yulianti1Mugahed Amran2Chung-Chan Hung3Department of Civil Engineering, National Cheng Kung University, 1, University Rd, Tainan City 701, TaiwanDepartment of Civil Engineering, National Cheng Kung University, 1, University Rd, Tainan City 701, TaiwanDepartment of Civil Engineering, College of Engineering, Prince Sattam Bin Abdulaziz University, Alkharj 11942, Saudi ArabiaDepartment of Civil Engineering, National Cheng Kung University, 1, University Rd, Tainan City 701, Taiwan; Corresponding author.Ultra-high-performance concrete (UHPC) is renowned for its superior mechanical and durability characteristics. While many studies have focused on thermal effects such as explosive spalling and the compressive and flexural properties of UHPC, there is limited research on its residual uniaxial tensile behavior. Moreover, variations in the heating rates adopted across different studies further complicate the ability to formulate broad, generalizable conclusions. This study aims to address these gaps by systematically investigating the thermal behavior of unconfined steel-fiber reinforced UHPC in line with the ASTM E119 standard fire exposure. Methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), and mechanical and durability testing were employed to comprehensively assess UHPC's post-fire performance at ambient temperature. Results revealed that by 200 ˚C, portlandite began converting into calcium oxide and water vapor. Simultaneously, levels of calcium silicate hydrate and calcium carbonate rose, indicating continued hydration at elevated temperatures. SEM imaging exposed significant microstructural issues at 300 ˚C, including debonding between fibers and the matrix, alongside microcracking and degradation at the aggregate-cement paste interface. This deterioration correlated with a significant increase in porosity, permeability, and water absorption, particularly at 300 ˚C. Although compressive strength continued to rise, peaking at 300 ˚C, tensile properties only showed optimal performance up to 200 ˚C before declining, demonstrating a differential impact of temperature on UHPC’s mechanical behavior. Despite this, UHPC displayed tensile strain-hardening behavior up to 300 ˚C, with post-peak strain increasing from 0.2 % at ambient temperature to 0.66 % at 300 ˚C. Nevertheless, a 1.5 % volume fraction of steel fibers proved ineffective in restraining explosive failure at temperatures exceeding 300 ˚C.http://www.sciencedirect.com/science/article/pii/S2214509524013251High temperaturesChemical constituentsMicrostructureDurabilityTensile strain-hardening |
| spellingShingle | Sohit Agrawal Erika Yulianti Mugahed Amran Chung-Chan Hung Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposure Case Studies in Construction Materials High temperatures Chemical constituents Microstructure Durability Tensile strain-hardening |
| title | Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposure |
| title_full | Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposure |
| title_fullStr | Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposure |
| title_full_unstemmed | Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposure |
| title_short | Behavior of unconfined steel-fiber reinforced UHPC post high-temperature exposure |
| title_sort | behavior of unconfined steel fiber reinforced uhpc post high temperature exposure |
| topic | High temperatures Chemical constituents Microstructure Durability Tensile strain-hardening |
| url | http://www.sciencedirect.com/science/article/pii/S2214509524013251 |
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