Journal of the Korean GEO-environmental Society (한국지반환경공학회 논문집)

Korean Geo-Environmental Society (한국지반환경공학회)
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Strength Development Characteristics of Clay Stabilized with Electric Furnace Steel Slag

전기로 제강슬래그로 안정화된 연약점토의 강도 발현 특성

  • Hyeongjoo Kim (Department of Civil Engineering, Kunsan National University) ;
  • Taegew Ham (Renewable Energy Research Institute, Kunsan National University) ;
  • Taewoong Park (Department of Civil and Environmental Engineering, Kunsan National University) ;
  • Taeeon Kim (Department of Civil and Environmental Engineering, Kunsan National University)
  • Received : 2024.04.11
  • Accepted : 2024.04.24
  • Published : 2024.05.01
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Abstract

This study aimed to investigate the changes in chemical components that occur when weak clay is mixed with steel slag modified with calcium oxide, and to understand the expression characteristics of compressive strength according to hydrophilicity and curing time. XRF testing, SEM imaging, vane shear strength and uniaxial compressive strength testing were conducted. Calcium (Ca) released from the steel slag increases the Ca content in clay by increasing the number of crystal particles and forming a coating layer known as calcium silicate hydrate (CaO-SiO2-H2O) through chemical reactions with SiO2 and Al2O3 components. The weak clay stabilized with steel slag is classified into an initial inactive zone where strength relatively does not increase and an activation zone where strength increases over curing time. The vane shear strength of the initial inactive area was found to be 4.4 to 18.4 kN/m2 in the state of the weight mixing ratio Rss 30% (steel slag 30% + clay 70%). In the case of the active area, the maximum uniaxial compressive strength increased to 431.8 kN/m2 after 480 hours of curing time, which increased due to the apparent adhesion strength of clay through pozzolanic reaction. Therefore, considering the strength expression characteristics of stabilized mixed clay based on the mixing ratio (Rss) during the recycling of steel slag can enhance its practicality in civil engineering sites.

본 연구는 산화칼슘 개질제로 제강슬래그를 사용하여 연약점토와 혼합 시 발생하는 화학적 성분의 변화가 수경성 및 양생시간에 따른 압축강도 발현 특성을 파악하고자 XRF시험과 SEM 촬영, 베인전단강도, 일축압축강도시험을 수행하였다. 제강슬래그로부터 용출되는 칼슘(Ca)은 점토 내 Ca 함량을 증가시키고, SiO2 및 Al2O3 성분과의 화학적 반응으로 칼슘실리카게이트 수화물 (CaO-SiO2-H2O) 반응으로 점토의 피막층이 형성되어 결정체 입자수를 증가시킨다. 따라서, 중량혼합비 Rss 30%(제강슬래그 30% + 점토 70%) 상태에서 초기 비활성영역의 베인전단강도는 4.4~18.4kN/m2로 나타났다. 활성영역의 경우 양생시간 480시간 경과 시 최대일축압축강도는 431.8kN/m2까지 증가되었으며, 이는 포졸란 반응에 의해 점토의 겉보기 점착(Attraction) 강도를 증가시킨다. 본 연구를 통해 토목현장에서 제강슬래그의 재활용을 위해 연약점토와 혼합 시 제강슬래그의 혼합율(Rss)에 따라 연약점토는 강도발현이 되므로 활용성을 높일 수 있다.

Keywords

Acknowledgement

본 연구는 2020년도 및 2021년도 정부(교육부)의 재원으로 한국연구재단의 지원을 받아 수행된 4단계 BK21 미래인재양성사업과 기초연구사업임(4299990614343, NRF-2021R1A6A1A03045185).

References

  1. Ahmedzade, P. and Sengoz, B. (2009), Evaluation of steel slag coarse aggregate in hot mix asphalt concrete, Journal of Hazardous Materials, Vol. 165, pp. 300~305.
  2. Horpibulsk, S., Rachan, R. Suddeepong, A. and Chinkulkijniwat, A. (2011), Strength development in cement admixed Bangkok clay: laboratory and field investigations, Soils and Foundations, Vol. 51, No. 2, pp. 239~251.
  3. Kim, J. M. and Park, H. I. (2012), Properties of steel slag aggregate for concrete, Magazine of the Korea Concrete Institute, Vol. 24, No. 6, pp. 35~38 (In Korean). https://doi.org/10.22636/MKCI.2012.24.6.35
  4. Kim, Y. W., Oh, M. H., Park, J. B. and Kwon, O. S. (2014), Removal efficiency of heavy metals and nutrients by zeolite and basic oxygen furnace Slag, Journal of the Korean Geo-Environmental Society, Vol. 15, No. 11, pp. 13~19 (In Korean). https://doi.org/10.14481/jkges.2014.15.11.13
  5. Lee, K. S., Lee, Y. K., Choi, J. S. and Han, H. M. (2010), An experimental study on the development of soft ground firming agent using EAF reduction slag, Proceedings of the Korean Geotechical Society Conference, pp. 998~1001 (In Korean).
  6. Lee, S. H., Kim, W. K. and Kang, S. H. (2012), Hydration mechanism of ground granulated blast furnace slag, Magazine of the Korea Concrete Institute, Vol. 24, No. 6, pp. 31~34 (In Korean).
  7. Lorenzo, G. A. and Bergado, D. T. (2004), Fundamental parameters of cement-admixed clay-new approach, Journal of Geotechnical and Geoenvironmental Engineering, Vol. 130, No. 10, pp. 1042~1050.
  8. Miura, N., Horpibulsk, S. and Nagaraj, T. S. (2001), Engineering behavior of cement stabilized clay at high water content, Soils and Foundations, Vol. 41, No. 5, pp. 33~45.
  9. Na, H. S., Yoon, Y. W. and Yoon, G. L. (2011), Environmental effect of the reduced slag in the electric furnace, Journal of the Korean Geo-Environmental Society, Vol. 12, No. 7, pp. 23~29 (In Korean).
  10. Seng, S. and Tanaka, H. (2011), Properties of cement-treated soils during initial curing stages, Soils and Foundation, Vol. 51, No. 5, pp. 775~784.
  11. Shi, C. (2004), Steel Slag-Its Production, Processing, Characteristics, and Cementations Properties, Journal of Materials in Civil Engineering, Vol. 16, No. 3, pp. 230~236.
  12. Shin, J. W., Yoon, Y. W. and Yoon, G. L. (2011), Geotechnical characteristics of reduced slag-soil mixtures in electric furnace, Journal of the Korean Geo-Environmental Society, Vol. 12, No. 7, pp. 31~37 (In Korean). https://doi.org/10.14481/JKGES.2011.12.7.4
  13. Tang, Y. X., Miyazaki, Y. and Tsuchida, T. (2001), Practices of reused dredging by cement treatment, Soils and Foundations, Vol. 41, No. 5, pp. 129~143.