논문 상세보기

Influence of Si/Al Ratio and Curing Temperature of Geopolymer Waste Forms on Immobilization of Radioactive Borate Waste

  • 언어ENG
  • URLhttps://db.koreascholar.com/Article/Detail/430480
모든 회원에게 무료로 제공됩니다.
한국방사성폐기물학회 학술논문요약집 (Abstracts of Proceedings of the Korean Radioactive Wasts Society)
한국방사성폐기물학회 (Korean Radioactive Waste Society)
초록

Immobilization of radioactive borate waste containing a high boron concentration using cement waste form has been challenged because the soluble borate phase such as boric acid reacts with calcium compounds, hindering the hydration reaction in cement waste form. Metakaolin-based geopolymer waste form which has a pure aluminosilicate system without calcium can be a promising alternative for the cement; however, secondary B-O-Si networks are formed by a reaction between borate and silicate, resulting in poor mechanical characteristics such as low compressive strength and final setting retardation. Thus, it is important to optimize the Si/Al molar ratio and curing temperature which are critical parameters of geopolymer waste form to increase borate waste loading and enhance the durability of geopolymer. Here, metakaolin-based geopolymer waste form to immobilize simulant radioactive borate waste was fabricated by varying the Si/Al molar ratio and curing temperature. The 7 days-compressive strength results reveals that the Si/Al molar ratio of 1.4 and curing at 60°C is advantageous to achieving high waste loading (30wt%). In addition, geopolymer waste forms with the highest borate waste loading exceeded the 3.445 MPa after the waste form acceptance criteria such as thermal cycling, gamma irradiation, and water immersion tests. The leachability index of boron was 7.56 and the controlling leaching mechanism was diffusion. The thermal cycling and gamma irradiation did not significantly change the geopolymer structure. The physically incorporated borate waste was leached out from geopolymer waste form during leaching and water immersion tests. Considering these results, metakaolin-based geopolymer waste form with a low Si/Al ratio is a promising candidate for borate waste immobilization, which has been difficult using cement.

저자
  • Byoungkwan Kim(Pohang University of Science and Technology, 77, Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do)
  • Jaehyuk Kang(Pohang University of Science and Technology, 77, Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do)
  • Younglim Shin(Pohang University of Science and Technology, 77, Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do)
  • Tae-min Yeo(Pohang University of Science and Technology, 77, Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do)
  • Wooyong Um(Pohang University of Science and Technology, 77, Cheongam-ro, Nam-gu, Pohang-si, Gyeongsangbuk-do) Corresponding author