Comparison of Long-Term Strength Development of Steel Fiber Shotcrete with Cast Concrete Based on Accelerator Type
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Department of Civil Engineering, Kangwon National University, 1 Gangwondaegil, Chuncheon 24341, Korea
2
KIIT (Kangwon Institute of Inclusive Technology), Kangwon National University, 1 Gangwondaegil, Chuncheon 24341, Korea
*
Authors to whom correspondence should be addressed.
Materials 2020, 13(24), 5599; https://doi.org/10.3390/ma13245599
Received: 21 November 2020
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Revised: 4 December 2020
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Accepted: 7 December 2020
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Published: 8 December 2020
(This article belongs to the Collection Concrete and Construction Materials)
This study analyzed the effect of accelerating agents, such as aluminate, cement mineral, and alkali-free accelerators, on the long-term performance of steel-fiber-reinforced shotcrete. The shotcrete performance was studied based on the type and amount of steel fiber added. Performance tests were performed to identify the accelerator providing better long-term performance to the steel-fiber-reinforced shotcrete. Changes in strength and flexural performance over time were investigated. The compressive strength and flexural strength tests on 1-, 3-, 6-, 12-, and 24-month-old test specimens were performed, wherein 37 kg of steel fiber was added to the cement mineral and aluminate mixes, and 40 kg of steel fiber was added to the alkali-free mix. The 1-month compressive strength result of all the test variables satisfied the Korea Expressway Corporation standard. The compressive strength of the cast concrete and shotcrete specimens increased with age, demonstrating a strength reduction, particularly in the 24-month-old shotcrete specimens. Thus, the shotcrete performance may deteriorate in the long-term. In the 24-month-old specimen, substantial flexural strength reduction was observed, particularly in the aluminate and alkali-free specimens. The relative strength of the specimens was compared with that of the cast concrete mold specimens. The results suggest the use of alkali-free accelerators, considering the long-term performance of tunnels and safety of workers. Moreover, increasing the steel fiber performance rather than the amount of low-performance steel fiber must be considered.
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Keywords:
steel fiber shotcrete; long-term performance; accelerators types; cement mineral accelerator; aluminate accelerator; alkali-free accelerators; tunnel site
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MDPI and ACS Style
Yun, K.K.; Choi, S.; Ha, T.; Hossain, M.S.; Han, S. Comparison of Long-Term Strength Development of Steel Fiber Shotcrete with Cast Concrete Based on Accelerator Type. Materials 2020, 13, 5599. https://doi.org/10.3390/ma13245599
AMA Style
Yun KK, Choi S, Ha T, Hossain MS, Han S. Comparison of Long-Term Strength Development of Steel Fiber Shotcrete with Cast Concrete Based on Accelerator Type. Materials. 2020; 13(24):5599. https://doi.org/10.3390/ma13245599
Chicago/Turabian StyleYun, Kyong K., Seunghak Choi, Taeho Ha, Mohammad S. Hossain, and Seungyeon Han. 2020. "Comparison of Long-Term Strength Development of Steel Fiber Shotcrete with Cast Concrete Based on Accelerator Type" Materials 13, no. 24: 5599. https://doi.org/10.3390/ma13245599
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