Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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Fundamental Research on Reactivity of Silica Source in the Rapidly Cured Inorganic Micro-Defect-Free(MiDF) Concrete

촉진 양생한 무기계 MiDF 콘크리트에서 실리카질 원료의 반응성에 관한 기초 연구

  • Choi, Hong-Beom (Department of Architectural Engineering, Kongju National University) ;
  • Kim, Jin-Man (Department of Architectural Engineering, Kongju National University)
  • Received : 2019.05.31
  • Accepted : 2019.06.28
  • Published : 2019.06.30
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Abstract

In this paper, the reaction properties of silica source in the accelerated curing conditions using autoclave and the fundamental properties of inorganic Micro Defect Free(MiDF) concrete using silica source are studied. Studies show that Si ions elution rate from silica source in autoclave curing is higher in amorphous source. In tap water conditions, solids which is source after autoclaved curing show a higher mass reduction in amorphous materials, which is attributed to the higher elution rate of ion. In $Ca(OH)_2$ solution conditions, amorphous materials show higher mass increase, due to increase in C-S-H minerals. From experiment for influence on the properties of MiDF concrete by using nano silica materials, the specimen with silica fume shows an increase in compressive strength and a decrease in absorption depending on replacement rate up to 5.5%, while nano silica with amorphous phase and high-fineness shows a decrease in compressive strength and decrease in the water absorption. The specimen with nano silica increases the pore below 10,000nm, but reduces pore between 10,000 and 100,000nm. The above results show that the porosity and absorption rate of MiDF concrete can be reduced by using amorphous nano-size silica. However, to reduce the pore of 50 to 10,000nm, better dispersion of nano material in the cement matrix will be necessary. We will focus on the this item in the next research.

본 연구에서는 오토클레이브를 활용한 촉진양생 조건에서 실리카 원료의 반응 특성 및 이를 활용한 무기계 MiDF 콘크리트의 기초 특성을 검토하였다. 다양한 나노 물질의 반응성을 알아보기 위한 용출 특성 실험에서 오토클레이브 양생 시 Si 이온의 용출은 비결정질의 원료에서 더 높게 나타났다. 상수 분위기에서 오토클레이브 양생된 고형물은 비결정질 원료일수록 높은 질량 감소를 보였는데, 이는 이온의 용출량이 높기 때문으로 사료된다. $Ca(OH)_2$ 수용액 조건에서는 비결정질 원료가 많은 질량 증가를 보였는데, 이는 C-S-H의 생성에 기인한 것이다. 나노 실리카 재료가 MiDF의 특성에 미치는 실험에서 실리카 퓸은 대체율 5.5%까지 MiDF의 압축강도 증가와 흡수율 감소에 기여하였고, 비결정질의 고분말도 나노 실리카는 대체율이 증가함에 따라 압축강도는 저하하였지만 흡수율 감소에 기여하였다. 또한 나노 실리카를 첨가한 시험체는 기대와 달리 10,000nm 이하의 공극은 증가하였지만, 10,000~100,000nm 범위의 공극은 감소하는 것으로 나타났다. 이상의 결과를 통해 비정질의 나노 사이즈 실리카를 활용하여 MiDF 콘크리트의 공극 및 흡수율을 저감이 가능함을 알 수 있었다. 그러나 목표로 하였던 50~10,000nm 사이의 공극을 줄이기 위해서는 시멘트 매트릭스에 나노 재료를 더욱 잘 분산시키는 것이 필요할 것이며, 이에 관한 연구가 지속될 필요가 있다.

Keywords

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Fig. 1. Operation condition of autoclave

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Fig. 2. Mold for manufacture

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Fig. 3. Ca ion depending on curing time and solution

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Fig. 4. Si ion depending on curing time and solution

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Fig. 5. Weight change depending on curing time and solution

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Fig. 6. Mineral analysis depending on solution

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Fig. 7. Mineral analysis of silica source in Ca(OH)2 solution

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Fig. 8. Compressive strength and water absorption of MiDF concrete

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Fig. 9. Incremental intrusion pore distribution of MiDF concrete

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Fig. 10. Cumulative intrusion of MiDF concrete

Table 1. Chemical composition of materials

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Table 2. Blaine of materials

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Table 3. Experimental plan for silica source reaction in autoclave condition

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Table 4. Experimental plan for MiDF concrete

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Table 5. Mix design for MiDF concrete

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