Journal of the Korea Institute of Building Construction (한국건축시공학회지)

The Korean Institute of Building Construction (한국건축시공학회)
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Mechanical Properties of Alpha-Calcium Sulfate Hemihydrate Replaced Concrete for Application to Box Culvert Power Transmission

전력구 콘크리트 구조물 적용을 위한 알파형 반수석고 치환 콘크리트의 역학적 특성

  • Received : 2018.10.16
  • Accepted : 2019.01.09
  • Published : 2019.02.20
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Abstract

This study evaluated the mechanical properties of the alpha-calcium sulfate hemihydrate replaced concrete to reduce the cracking in a box culvert power transmission. After setting the replacement ratio of alpha-calcium sulfate hemihydrate at 0, 6, 9, 12, and 15%, the setting time, compressive strength, and drying shrinkage were measured and the microstructure and crystal structure were analyzed. As a result, it was confirmed that as the replacement ratio of alpha-calcium sulfate hemihydrate increased, the setting time decreased and the compressive strength declined. On the other hand, when the alpha-calcium sulfate hemihydrate was set with 15% of replacement ratio, about 60% reduction in the drying shrinkage was shown compared to that of ordinary Portland cement. Therefore, it is thought that when the concrete replacing the alpha-calcium sulfate hemihydrate is applied to a box culvert power transmission, the cracking reduction performance will be improved, and the improvement of compressive strength will be required.

본 연구에서는 전력구 콘크리트 구조물에서 발생하는 균열저감을 위해 알파형 반수석고를 치환한 콘크리트의 역학적 특성을 평가하였다. 알파형 반수석고의 치환율은 0, 6, 9, 12, 15%로 설정하여, 응결시간, 압축강도, 건조수축을 측정하였으며, 미세구조 및 결정구조의 분석을 실시하였다. 실험 결과, 알파형 반수석고의 치환율이 증가할수록 응결시간이 단축되었으며, 압축강도가 저하되는 경향을 확인하였다. 한편, 알파형 반수석고를 15% 치환할 경우 보통포틀랜드시멘트 콘크리트에 비해 건조수축이 약 60% 저감되는 효과가 나타났다. 따라서, 전력구 콘크리트 구조물에 알파형 반수석고를 치환한 콘크리트를 적용할 경우 균열저감 성능이 향상될 것으로 판단되며, 압축강도의 개선은 필요할 것으로 판단된다.

Keywords

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Figure 1. SEM micrograph of alpha-calcium sulfate hemihydrate

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Figure 2. Particle size distribution of used materials

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Figure 3. Slump measurement results of alpha-calcium sulfate hemihydrate-replaced concrete

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Figure 4. Setting time measurement results of alpha-calcium sulfate hemihydrate-replaced concrete

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Figure 5. Compressive strength measurement results of alpha-calcium sulfate hemihydrate-replaced concrete

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Figure 6. Drying shrinkage measurement results of alpha-calcium sulfate hemihydrate-replaced concrete

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Figure 7. X-ray diffraction analysis

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Figure 8. SEM micrographs (Age 7 days)

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Figure 9. SEM micrographs (Age 28 days)

Table 1. Physical properties of materials

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Table 2. Chemical compositions of materials

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Table 3. Experimental plan

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Table 4. Mix proportion of concrete

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References

  1. Kevin J, Neal S. Properties of high-performance concrete containing shrinkage-reducing admixture. Cement and Concrete Research. 1997 Jul;27(9):1357-64. https://doi.org/10.1016/S0008-8846(97)00135-X
  2. Woo SK, Chu IY, Kim KJ, Lee Y. Cracking behavior of concrete box culvert for power transmission due to drying shrinkage. Journal of the Korea Institute for Structural Maintenance and Inspection. 2016 Jan;20(1):1-8. https://doi.org/10.11112/JKSMI.2016.20.1.001
  3. Kwon KJ, Oh SK. A performance test method of waterproofing system to evaluate the responsiveness to the movement of box culvert structure for underground electronic power facility(Mock-up test method of waterproofing layer to response 10mm movement of expansion joint). Magazine of the Korea Concrete Institute. 2008 Jul;20(4):57-62. https://doi.org/10.22636/MKCI.2008.20.4.57
  4. Lee KH, Kim GY, Lee BK, Shin KS, Nam JS. Setting time, compressive strength and drying shrinkage of mortar with alpha-calcium sulfate hemihydrate. Journal of the Korea Institute for Structural Maintenance and Inspection. 2017 Sep;21(5):117-24. https://doi.org/10.11112/JKSMI.2017.21.5.117
  5. Lee KH, Kim GY, Lee BK, Kim RH, Shin KS. Evaluation of hardening properties and dry shrinkage of non-sintered binder based floor mortar utilizing alpha-hemihydrate gypsum. Journal of The Korean Institute of Building Construction. 2015 Aug;15(4):359-65. https://doi.org/10.5345/JKIBC.2015.15.4.359
  6. Sung GM, Moon JH, Park MA. Manufacture and applications of the high strength ${\alpha}$-calcium sulfate hemihydrate using FGD gypsum. Journal of The Korean Recycled Construction Resources Institute. 2009 Dec;4(4):50-3.
  7. Lee KH, Yang KH. Evaluation of pH and compressive strength development of alpha-calcium sulfate hemihydrate-based binder. Journal of The Korean Institute of Building Construction. 2016 Feb;16(1):59-65. https://doi.org/10.5345/JKIBC.2016.16.1.059