Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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An Experimental Study on the Improvement of Quality of Mixed Aggregate Using Recycled Aggregate

순환골재 사용 혼합골재의 품질 개선을 위한 실험적 연구

  • Kim, Jung-Ho (Technology Research Center, Halla Encom) ;
  • Sung, Jong-Hyun (Technology Research Center, Halla Encom) ;
  • Kim, Choong-Gyum (Technology Research Center, Halla Encom) ;
  • Lee, Sea-Hyun (Dept. of Living and Built Environment Research, Korea Institute of Civil engineering and Building Technology) ;
  • Kim, Han-Soo (Dept. of Architectural Engineering, Konkuk University)
  • 김정호 (한라엔컴 기술연구소) ;
  • 성종현 (한라엔컴 기술연구소) ;
  • 김충겸 (한라엔컴 기술연구소) ;
  • 이세현 (한국건설기술연구원 건축도시연구소) ;
  • 김한수 (건국대학교 건축공학과)
  • Received : 2018.09.17
  • Accepted : 2018.12.06
  • Published : 2018.12.30
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Abstract

In this study, recycled aggregate and natural aggregate were mixed in advance using an aggregate mixing facility that was developed to improve the quality of recycled aggregate concrete. Then the mixed aggregate was applied and concrete characteristics before and after a mix were considered. Based on the findings extracted, this study aimed to suggest a new direction for quality stabilization and application activation of recycled aggregate. The test results of change rates of mortars and coarse aggregates in fresh concrete mixed by a concrete mixer, before and after mixing aggregates showed that the variations of the mortars and coarse aggregates in the concrete mixed with the aggregates beforehand were decreased than those in the concrete before mixing them. The variation of compressive strength and the mean compressive strength at the ages of 3 and 7 days showed similar results before and after the aggregates were mixed, and the strength at the age of 28 days before and after mixing them showed larger deviation than that at the ages of 3 and 7 days. The use of the mixed aggregates after mixing aggregates beforehand reduced the variation in strength and is believed that it is advantageous for long-age strength development. The above results show that the variations of coarse aggregates and compressive strength in the concrete using the mixed aggregates produced by mixing recycled aggregates and natural aggregates beforehand are reduced so it will be possible to produce the homogeneous concrete by mixing aggregates beforehand.

본 연구에서는 순환골재 콘크리트의 품질안정화를 목표로 기술 개발한 골재 혼합설비를 활용하여 순환골재 및 천연골재를 사전 혼합하였으며, 생산 된 혼합골재를 적용하여 혼합 전과 혼합 후의 콘크리트 특성을 검토하였다. 이렇게 도출된 결과를 토대로 순환골재의 품질 안정화 및 사용 활성화를 위한 새로운 방향을 제시하고자 하였다. 골재 혼합 전 후에 따른 믹서로 비빈 굳지 않은 콘크리트 중의 모르타르와 굵은 골재량의 변화율 시험 결과 사전 골재 혼합 시 혼합 전 콘크리트 대비 모르타르 및 굵은 골재량의 편차가 줄어드는 것으로 확인되었다. 재령 3일과 재령 7일에서의 압축강도 편차 및 평균압축강도는 혼합 전 후 비슷한 결과를 나타냈으며, 28일 강도에서는 재령 3, 7일보다 혼합 전 후 강도 편차가 크게 발생했다. 사전 골재 혼합을 통한 혼합골재 사용 시 강도 편차가 줄어드는 것으로 확인되었으며, 사전 골재 혼합을 통한 혼합골재 사용 시 장기강도 발현이 유리할 것으로 사료된다. 위의 결과를 토대로 순환골재 및 천연골재 사전 혼합을 통해 생산된 혼합골재를 사용한 콘크리트 결과 굵은골재량, 압축강도 편차가 줄어드는 것으로 나타나 사전 골재혼합을 통해 균질한 콘크리트를 생산할 수 있는 것으로 판단된다. 이는 생산되는 순환골재 특성에 따라 천연골재와 사전 혼합을 통해 균질한 골재 특성을 맞춰 생산할 수 있으며, 순환골재의 문제점 중 하나인 품질편차를 해결할 방안으로 고려된다.

Keywords

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Fig. 1. Aggregate mixing facility

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Fig. 2. Method of aggregate mixing

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Fig. 3. Grain size distribution ratio of fine aggregate

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Fig. 4. Grain size distribution ratio of coarse aggregate

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Fig. 5. Difference in unit volume weight of the mortar

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Fig. 6. Difference in coarse aggregate volume

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Fig. 7. Compressive strength of initial discharge

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Fig. 8. Compressive strength of final discharge

Table 1. Plan of experiment

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Table 2. Properties of cement

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Table 3. Physical properties of aggregate

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Table 4. Properties of plasticizer

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Table 5. Mixing proportion

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Table 6. Result of fresh concrete

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Table 7. Result of compressive strength

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References

  1. Kim, J.H. (2011). An experimental study on the concrete performance improvement using pre-mixer, Korea Concrete Institute, 287-288 [in Korean].
  2. Lee, S.H., Shim, J.W. (2010). Enactment Provision of Recycled Aggregate Concrete, Journal of the Korea concrete Institute, 22(1), 33-35 [in Korean].
  3. Seo, C.H., Kim, B.Y. (2005). An experimental study on the durability of recycled aggregate concrete, Journal of the Korea concrete Institute, 17(3), 385-392 [in Korean]. https://doi.org/10.4334/JKCI.2005.17.3.385
  4. Yang, I.H., Jeong, J.Y. (2016). Effect of recycled coarse aggregate on compressive strength and mechanical properties of concrete, Journal of the Korea concrete Institute, 28(1), 105-113 [in Korean]. https://doi.org/10.4334/JKCI.2016.28.1.105