한국건설순환자원학회논문집 (Journal of the Korean Recycled Construction Resources Institute)

한국건설순환자원학회 (Korean Recycled Construction Resources Institute)
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혼합방법에 따른 순환아스팔트 혼합물의 수분저항성 통계검정 평가

Statistical Evaluation of Moisture Resistance by Mixing Method of Recycled Asphalt Mixtures

  • 김성운 (강원대학교 첨단건설기술연구소) ;
  • 김영삼 (강원대학교 지역건설공학과) ;
  • 조영진 (한국건설생활환경시험연구원 대구.경북지원) ;
  • 김광우 (강원대학교 지역건설공학과)
  • Kim, Sungun (Advanced Construction Research Center, Kangwon National University) ;
  • Kim, Yeongsam (Department of Regional Infrastructure Engineering, Kangwon National University) ;
  • Jo, Youngjin (Daegu & Gyeongbuk Branch, Korea Conformity Laboratories) ;
  • Kim, Kwangwoo (Department of Regional Infrastructure Engineering, Kangwon National University)
  • 투고 : 2021.04.06
  • 심사 : 2021.06.12
  • 발행 : 2021.06.30
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초록

순환아스팔트 혼합물은 제조 시 믹서에서 혼합되는 동안 노화된 RAP(회수 아스팔트포장재)을 잘 녹이는 것이 중요하다. 순환아스팔트 혼합물은 모든 재료(RAP, 신규 아스팔트 및 신규 골재)를 동시에 믹서에 넣고 혼합하여 생산한다. 동시 혼합(IM)방법으로 제조된 순환아스팔트 혼합물의 경우 RAP에 포함된 노화된 바인더는 신규 바인더와 혼합되는 동안 적절하게 회생되지 못하기 때문에 동일한 혼합물 내에서 신규 골재 주위에 코팅된 바인더보다 더 높은 산화·노화 수준을 나타내며, 큰 강성을 보인다. 본 연구에서는 RAP의 노화된 바인더를 회생시키기 위해서 단계 혼합(SM) 방법을 적용하였다. 첫 번째 단계에서는 RAP과 신규 아스팔트를 혼합한 다음 두 번째 단계에서는 가열된 신규 골재와 함께 혼합하였다. 혼합 방법에 따른 순환아스팔트 혼합물의 수분저항성 개선효과를 비교하기 위해 간접인장강도(ITS)와 인장강도 비(TSR) 시험을 수행하여 SM 방법과 IM 방법 간에 통계적 t- 테스트를 수행했다. 수분저항성을 평가하기 위해서 세 가지 전처리 조건 즉, -18℃ 동결 후 60℃에서 24 시간 수침, 60℃에서 48 시간 수침 및 60℃에서 72 시간 수침 조건을 적용하였다. SM 방법으로 제조한 순환아스팔트 혼합물의 TSR은 IM 방법에 의한 순환아스팔트 혼합물보다 분명히 높았고, SM 방법의 변동계수는 IM보다 낮았다. 또한 통계적 t-test에 의해 SM 방법의 ITSWET이 α = 0.05 수준에서 IM과 유의하게 다른 것으로 관찰되었다. 또한, SM 방법의 ITSWET은 IM과 비교하여 더 가혹한 조건에서 처리할수록 훨씬 개선된 결과를 나타냈다. 따라서 단계 혼합 방법은 기존의 동시 혼합방법으로 생산된 순환아스팔트 혼합물보다 더 높은 수분저항성을 보이고, 보다 더 우수한 순환아스팔트 혼합물을 생산하기 위한 중요한 혼합 방법임을 확인하였다.

When producing recycled asphalt mix, it is important that the old binder of reclaimed asphalt pavement(RAP) should be well melted during blending in the mixer. The recycled asphalt mix is produced by instant mixing(IM) of all materials(RAP, virgin asphalt and new aggregates) all together in the mixer. However, in the same recycled mix, the binder around RAP aggregate was found to show higher oxidation level than the binder coated around the virgin aggregate because the old binder of RAP was not rejuvenated properly while instant mixing. The partially-rejuvenated RAP binder is assumed to be a high stiffness point in IM recycled mix. In this study, the stage mixing(SM) method was introduced; blending RAP and virgin asphalt for the first stage, and then mixing all together with hot new aggregates for the second stage. To compare the effect of the two mixing methods on moisture resistance of recycled mixes, a statistical t-test was performed between SM and IM using indirect tensile strength(ITS) and tensile strength ratio(TSR). Three conditioning methods were used; a 16-h freezing and then 24-h submerging, 48-h submerging, and 72-h submerging in 60℃ water. It was found that the TSR(=ITSwet/ITSdry) values of the mixes prepared by SM was clearly higher than the IM mixes, and coefficients of variation of SM mixes were lower than the IM mixes. It was also observed that the ITSWET of SM was significantly different from the IM at α=0.05 level by statistical t-test. The ITSWET of SM mix was reduced less than the IM mix in severer conditioned mixes. Therefore, it was concluded that the stage mixing method was an important blending technique for producing better-quality of recycled asphalt mixes, which would show higher moisture resistance than the recycled mixes produced by conventional instant mixing.

키워드

과제정보

본 연구는 2019년도 정부(과학기술정보통신부)의 재원으로 한국연구재단 공공조달 연계형 국민생활연구 실증·사업화 사업의 지원을 받아 수행된 연구(No. 2019M3E8A1067629)로서 강원대학교 첨단건설기술연구소의 시설·장비를 이용하여 수행되었습니다.

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