Journal of the Korea Institute of Building Construction (한국건축시공학회지)

The Korean Institute of Building Construction (한국건축시공학회)
권호 표지
DOI QR코드

DOI QR Code

Mineralogical Analysis of Calcium Silicate Cement according to the Mixing Rate of Waste Concrete Powder

폐콘크리트 미분말 치환율에 따른 이산화탄소 반응경화 시멘트의 광물상 분석

  • Lee, Hyang-Sun (Carbon Neutral Materials Center, Korea Institute of Ceramic Engineering and Technology) ;
  • Song, Hun (Carbon Neutral Materials Center, Korea Institute of Ceramic Engineering and Technology)
  • Received : 2023.12.11
  • Accepted : 2024.02.23
  • Published : 2024.04.20
Download PDF
⟨ Previous Next ⟩

Abstract

In the realm of cement manufacturing, concerted efforts are underway to mitigate the emission of greenhouse gases. A significant portion, approximately 60%, of these emissions during the cement clinker sintering process is attributed to the decarbonation of limestone, which serves as a fundamental ingredient in cement production. Prompted by these environmental concerns, there is an active pursuit of alternative technologies and admixtures for cement that can substitute for limestone. Concurrently, initiatives are being explored to harness technology within the cement industry for the capture of carbon dioxide from industrial emissions, facilitating its conversion into carbonate minerals via chemical processes. Parallel to these technological advances, economic growth has precipitated a surge in construction activities, culminating in a steady escalation of construction waste, notably waste concrete. This study is anchored in the innovative production of calcium silicate cement clinkers, utilizing finely powdered waste concrete, followed by a thorough analysis of their mineral phases. Through X-ray diffraction(XRD) analysis, it was observed that increasing the substitution level of waste concrete powder and the molar ratio of SiO2 to (CaO+SiO2) leads to a decrease in Belite and γ-Belite, whereas minerals associated with carbonation, such as wollastonite and rankinite, exhibited an upsurge. Furthermore, the formation of gehlenite in cement clinkers, especially at higher substitution levels of waste concrete powder and the aforementioned molar ratio, is attributed to a synthetic reaction with Al2O3 present in the waste concrete powder. Analysis of free-CaO content revealed a decrement with increasing substitution rate of waste concrete powder and the molar ratio of SiO2/(CaO+SiO2). The outcomes of this study substantiate the viability of fabricating calcium silicate cement clinkers employing waste concrete powder.

석회석은 시멘트의 주원료로써 90% 이상을 사용하고 있으며, 고온 소성 과정에서 및 석회석의 탈탄산 반응으로 많은 양의 CO2를 배출한다. 이에 석회석 사용량 저감을 위해 원료를 대체할 수 있는 부산물에 관한 연구들이 진행 중이다. 또한 광물 탄산화는 기체인 CO2를 탄산염 광물로 전환하는 기술로 산업시설에서 배출되는 CO2를 포집하여 광물로 저장 및 자원화할 수 있다. 한편, 건설폐기물은 계속적으로 증가하는 추세로, 폐콘크리트는 많은 부분을 차지하고 있다. 폐콘크리트는 파쇄 및 분쇄를 통해 순환골재로써 활용되고 있으나 이때 발생하는 폐콘크리트 미분말은 유효하게 재이용 되지 못하고 대부분 폐기 또는 매립되는 실정이다. 이에 본 연구에서는 폐콘크리트를 석회석 대체재로써 활용하여 광물 탄산화 기술을 적용할 수 있는 이산화탄소 반응경화 시멘트 제조 가능성을 확인하고자 한다. 폐콘크리트 미분말 치환율 및 이산화탄소 반응 경화 시멘트의 주요 광물이 생성되는 조건인 SiO2/(CaO+SiO2) 몰비에 따른 광물 분석 결과, 폐콘크리트 미분말 치환율과 SiO2/(CaO+SiO2) 몰비가 높을수록 주요 광물인 Pseudowollastonite와 Rankinite 생성량이 증가하였다. 또한 세 가지 SiO2/(CaO+SiO2) 몰비에서 공통적으로 폐콘크리트 미분말을 50% 치환한 경우 Gehlenite가 생성되었으며, 생성량 또한 유사하였다. 이는 콘크리트 미분말에 함유하고 있는 Al2O3 성분이 CaO와 SiO2와 반응하여 Gehlenite가 합성된 것으로 판단된다. Gehlenite의 경우 Pseudowollastonite와 Rankinite와 같이 광물 탄산화를 통해 탄산염 광물인 CaCO3를 생성하는 산화물로써 이는 Al2O3가 함유된 산업부산물을 원료로 사용하는 경우 이산화탄소 반응경화 시멘트의 광물로써 활용이 가능할 것으로 기대한다.

Keywords

Acknowledgement

This experiment research had been conducted under the financial support provided by the R&D program(Development of calcium silicate cement and cement products, RS-2022-00155521) of KEIT.

References

  1. Bae SC, Moon JH, Nam JS. Global status of cement-concrete carbon neutrality. Journal of the Korea Concrete Institute. 2022 Jan;34(1):50-7. 
  2. Technology development strategy for carbon neutrality in the cement industry. [Internet]. Deagu (Korea): Institute of Industrial Technology; 2022 Aug 26. Available from: https://rome.keit.re.kr/romeplus/biz/myis/rndData/pdIssUeReportDetaile.do?searchCdtn=&searchKeyword=%EC%8B%9C%EB%A9%98%ED%8A%B8+%EC%82%B0%EC%97%85+%ED%83%84%EC%86%8C%EC%A4%91%EB%A6%BD%EC%9D%84+%EC%9C%84%ED%95%9C+%EA%B8%B0%EC%88%A0%EA%B0%9C%EB%B0%9C+%EC%A0%84%EB%9E%B5&pageIndex=1&blbdId=S0000010&blltSeq=91646 
  3. Jose MRM, Domingos DJCP, Nazare DSLSV, Aluisio ACJ, Romulo SA. Chemical and mineralogical characterization of portuguese ceramic tiles in the historic center of sao luis do maranhao (brazil): an approximation of the mineralogy and firing temperature of the raw materials. Rem: Revista Escola de Minas. 2013 Jan;66(1):91-8. 
  4. Abdulaziz A. The global carbon footprint and how new carbon mineralization technologies can be used to reduce CO2 emissions. Chem Engineering. 2022 Jun;6(3):44. https://doi.org/10.3390/chemengineering6030044 
  5. Jang NH, Shim HM, Hua XL, Kim HT. Evaluation of chemical pre-treatment for the optimization of CO2 fixatiom using by carbonation reaction with serpentine. Journal of Industrial and Engineering Chemistry. 2008 Oct;19(5):526-32. 
  6. Kim KH. Carbon dioxide storage by mineral carbonation. KISTI Market Report. 2014 Jan;4(1):16-9. 
  7. Hwang JH, Ji HU, Thao NH. Review of CO2 undersea storage technology and research on environmental impact technology. Coastal and Ocean. 2010 Sep;3(2):13-27. 
  8. Nationwide waste generation and treatment status in 2021 [Internet]. Incheon (Korea): Korea Environment Corporation; 2022 Dec 20. Available from: https://www.recycling-info.or.kr/rrs/stat/envStatDetail.do;jsessionid=CwbyBKJt1EDHB5HtRcFizpybJEZieSjvnxDmneDXqdAD5nOGbQmwPTpPt3j5Iual.RCIS-WAS_servlet_engine1?bbsId=BBSMSTR_000000000002&nttId=1306&s_nttSj=KEC006 
  9. Song H, Shin HU, Lee JK, Chu YS, Pack DC. Image and phase analysis of low carbon type recycled cement using waste concrete powder. Journal of the Korean Recycled Construction Resources Institute. 2014 Dec;2(4):314-20. https://doi.org/10.14190/JRCR.2014.2.4.314 
  10. Lee HS, Song H. Component and phase analysis of calcium silicate cement clinker by raw materials mix design. Journal of the Korea Institute of Building Construction. 2022 Jun;22(3):251-8. https://doi.org/10.5345/JKIBC.2022.22.3.251 
  11. Kim TY, Kim NI, Chu YS. Burnability and mineral properties of clinker added chlorine. Journal of Korean Institute of Resources Recycling. 2020 Dec;29(6):48-56. https://doi.org/10.7844/kirr.2020.29.6.48