Journal of the Korea Institute of Building Construction (한국건축시공학회지)

The Korean Institute of Building Construction (한국건축시공학회)
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Hydration Characteristics of Liquid Red Mud Mixed Cement Paste Neutralized with Sulfuric Acid

황산으로 중화시킨 액상 레드머드를 혼입한 시멘트 페이스트의 수화특성

  • Kang, Suk-Pyo (Department of Construction Engineering, Woosuk University) ;
  • Hong, Seong-Uk (Department of Construction Engineering, Woosuk University) ;
  • Kim, Sang-Jin (Department of Construction Engineering, Woosuk University) ;
  • In, Byung-Eun (Department of Construction Engineering, Woosuk University)
  • Received : 2022.07.13
  • Accepted : 2022.09.21
  • Published : 2022.10.20
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Abstract

In this study, Neutralized red mud(LRM+S) at a pH of 6-8 was prepared by adding sulfuric acid to liquefied red mud(LRM) at a pH of 10~12. After adding LRM and LRM+S to the cement paste, the hydration heat, compressive strength, and hydration products were examined. The observed accumulated hydration heat revealed that the calorific value of the cement paste with LRM was low and its and peak was delayed when compared with that of plain cement paste(referred to as Plain), whereas the calorific value of the cement paste with LRM+S was similar to that of Plain. At the age of 28 days, the compressive strength of the cement paste with 20% LRM was 55% of the strength of Plain. Using X-ray diffraction, it was determined that the cement paste with 20% LRM exhibited a Ca(OH)2 peak after 3 days, whereas the cement paste with 20% LRM+S and Plain exhibited a Ca(OH)2 peak after an hour. Thus, the strength degradation of cementitious materials was improved by adding neutralized red mud prepared by adjusting the pH of highly alkaline LRM with sulfuric acid.

본 연구에서는 액상 레드머드를 첨가한 시멘트계 재료의 강도저하를 개선하기 위해서, pH가 10~12인 액상 레드머드(LRM)에 황산을 첨가하여 pH를 6~8로 조절한 중화레드머드(LRM+S)를 제조하였다. LRM과 LRM+S를 각각 시멘트 페이스트에 첨가하여 수화열, 압축강도, 수화생성물을 확인하였다. 수화열 측정결과 LRM을 첨가한 시멘트 페이스트는 Plain와 비교하여 발열량이 낮고 수화속도가 지연되었지만, LRM+S를 첨가한 시멘트 페이스트는 Plain의 수화열 피크와 유사하게 나타났다. 압축강도 측정결과 PS-LRM의 압축강도는 모든 재령에서 Plain의 압축강도보다 저하되었고 28일 재령에서 55% 수준을 나타내었다. 반면에 PS-LRM+S의 압축강도는 Plain의 압축강도와 비교하여 28일 재령에서 유사한 수준을 나타내었다. XRD 분석 결과 PS-LRM는 3일부터 Ca(OH)2 피크가 확인되었지만, PS-LRM+S의 경우 Plain과 유사하게 1시간부터 Ca(OH)2 피크가 나타났다. 따라서 강알칼리성의 액상 레드머드에 황산을 첨가하여 중화레드머드를 제조하여 시멘트계 재료에 첨가하면 강도저하를 개선할 수 있을 것으로 판단된다.

Keywords

Acknowledgement

This work is supported by the Korea Agency for Infrastructure Technology Advancement(KAIA) grant funded by the Ministry of Land, Infrastructure and Transport(Grant 22TBIP-C160747-02).

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