Journal of the Computational Structural Engineering Institute of Korea (한국전산구조공학회논문집)

Computational Structural Engineering Institute of Korea (한국전산구조공학회)
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Application of Gaussian Mixture Model for the Analysis of the Nanoindentation Test Results of the Metakaolin-based Geopolymer with Different Silicon-to-Aluminum Molar Ratio

실리콘-알루미늄 몰 비의 변화에 따른 메타카올린 지오폴리머의 나노인덴테이션 결과 분석을 위한 가우시안 믹스쳐 모델의 활용

  • Park, Sungwoo (Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology)
  • 박성우 (울산과학기술원 도시환경공학과)
  • Received : 2022.01.05
  • Accepted : 2022.03.31
  • Published : 2022.04.30
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Abstract

This study proposes the deconvolution method for the nanoindentation test results of geopolymer employing the Gaussian mixture model. Geopolymer has been studied extensively as an alternative construction material because it emits relatively lower CO2 compared to ordinary Portland cement. Geopolymer is made of aluminosilicate and alkaline solution, and the Si/Al molar ratio affects its mechanical properties. Previous studies revealed that the Si/Al molar ratio of 1.8~2.0 results in the highest compressive strength, and the Si/Al molar ratio over 1.8 degrades the compressive strength of geopolymer severely; however the reason for the compressive strength degradation is still unclear. To understand the effect of the Si/Al molar ratio on the geopolymer structure, this study exploits the nanoindentation. The phase deconvolution of the indent modulus data is successful using the Gaussian mixture model, and it is observed that the Si/Al molar ratio alters the homogeneity of the geopolymer. Geopolymer becomes more homogeneous up to an Si/Al molar ratio of 1.8 at which geopolymer exhibits the highest compressive strength. The examination of this study is assumed to be adopted as evidence of strength degradation by the Si/Al ratio higher than the optimum value.

본 논문에서는 지오폴리머의 상변화를 관찰하기 위하여 나노인덴테이션 데이터를 가우시안 믹스쳐 모델로 분석하는 방법을 제시하였다. 지오폴리머는 일반 시멘트 대비 CO2 발생량을 줄일 수 있어 시멘트 대체 재료로써 많은 연구가 이루어지고 있다. 기존 연구들로부터 최적의 실리콘/알루미늄 비율을 찾았으나 1.8 초과에서 압축강도 저하의 원인은 아직 불분명하다. 본 연구에서는 실리콘/알루미늄 비율이 재료에 미치는 영향을 조사하고자 나노인덴테이션 실험을 수행하였다. 실험 결과를 가우시안 믹스쳐 모델로 상분석하였고, 실리콘/알루미늄 비율이 증가할수록 재료가 균질거동을 하는 것을 관찰할 수 있었다. 본 연구결과는 강도저하를 규명하는데 직접적인 근거로 활용될 수 있을 것으로 기대된다.

Keywords

Acknowledgement

본 연구는 한국연구재단이 주관하는 박사후 국내연수 사업(No. 2.210988.01)의 지원을 받아 수행되었습니다.

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