• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.643-648
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• 2002

A research for recycling the demolished-concrete as concrete aggregate has been concerned in all over the world. There, however, are some problems that qualities of recycled aggregates are not only largely different, but also mechanical properties of recycled aggregate concrete decrease a little in comparison with that of natural aggregate concrete. In this study, the resistance of freezing and thawing of concrete using source-concrete recycled aggregate(SRN) and demolished-concrete recycled aggregate(DRA) was investigated. Futhermore a research for improvement of freeze and thaw durability of recycled aggregate concrete was performed. Relative dynamic modulus of elasticity of SRN and DRA recycled aggregate concrete was dropped 60% before 150 of freezing and thawing cycle, and was much lower than that of control concrete. Relative dynamic modulus of elasticity of recycled aggregate concrete was increased to decrease water-cement ratio, but the freeze and thaw durability of recycled aggregate concrete was not enough improved. Futhermore, when metakaolin and silica fume were repalced, the freeze and thaw durability of recycled aggregate concrete containg metakaolin was more improved than that of silica fume.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2004년도 학술대회지
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• pp.15-19
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• 2004

The production of waste concrete is increased continuously by urban renewal, reconstruction, remodeling, and so on. So the positive use of recycled aggregate concrete is needed. Research for recycled aggregate concrete that use recycled aggregate from the mid-80s to solve environmental problem of aggregate insufficiency and waste concrete is consisting vigorously. However, specifications and mix design about waste concrete's use are evading use of recycled aggregate concrete yet in spot being not taken a triangular position. Therefore. it analyze existing research data for recycled aggregate concrete collection to develop strength estimate program in this research. Recycled aggregate concrete's strength estimate program if specifications and mix design about recycled aggregate concrete are taken a triangular position to foundation recycled aggregate concrete's practical use to increase judge.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.169-172
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• 2004

Recently, because of the shortage of natural aggregate and the environment regulation of government, the application of recycled aggregate by solution method is observed according as the concern for the reuse of waste concrete. But because the quality of recycled aggregate is poor and quantitative quality judgment standard of recycled aggregate is fluffy, construction field application is difficult. Therefore, this study compares and investigates effect that quality of recycled aggregate influencing recycled concrete. As the result of this study, the more quality of aggregate increases, the more recycled concrete quality increased and high quality recycled aggregate generally displayed performance of similar level with nature aggregate. But, durability of recycled concrete using recycled aggregate appeared lower than concrete using natural aggregate without reference to aggregate quality.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 춘계 학술발표회 제16권1호
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• pp.384-387
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• 2004

Though recycled aggregate is useful resources for concrete, its application to structural frame is not frequent, because of low quality of recycled aggregate. Owing to the development of manufacturing technology to recycled aggregate, it is possible to produce high quality recycled aggregate. The purpose of this study is to confirm the applicability of the high quality recycled aggregate, instead of the natural aggregate, to normal concrete. Main factors of this study are substitute proportion of recycled aggregate, types of recycled aggregate, targeting compressive strength of recycled concrete. From the results of the study, we concluded that it is possible to use high quality recycled aggregate, to get the same strength as concrete using normal aggregate.

• 한국건축시공학회지
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• 제7권2호통권24호
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• pp.85-92
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• 2007

In the past, recycled aggregate was used very limitedly in low value-added areas such as the base layer of roads. However, in response to the shortage of natural aggregate, high consciousness of resource saving and changed idea on environment, the quality of recycled aggregate has been improved considerably, and the percentage of recycled construction waste is increasing every year compared to simple landfill or incineration. Recently the Act on the Promotion of Construction Waste Recycling was enacted on December 2003 for the efficient use of recycled aggregate, and the Standards for the Quality of Recycled Aggregate for Concrete (Proposal) were announced in order to use and manage recycled aggregate according to quality. According to the Standards for the Quality of Recycled Aggregate for Concrete (Proposal), it is recommended to substitute recycled coarse aggregate and fine aggregate below 30% each. However, compared to the trend of recycling, the recycling rate of aggregate is still quite low. It is because of low performance of recycled aggregate, users' lack of understanding, etc. These problems basically come from the decrease of strength of recycled concrete resulting from the use of recycled aggregate, and recycled aggregate is still considered not reliable because there have been not many cases of actual application. If the basic problem of strength decrease is solved and data on recycled aggregate is provided through actual field placing, we may maximize the use of recycled aggregate. Thus, in order to maximize the use of recycled aggregate that satisfy the recycled aggregate quality standards, the present study made a mock-up similar to real structures, evaluated its performance and examined the field applicability of recycled aggregate concrete.

• 지질공학
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• 제13권3호
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• pp.345-358
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• 2003

근래에 와서 천연골재자원의 보호와 건설 폐기물의 재활용의 측면에서 폐 콘크리트에서 분리한 재생골재의 재활용이 모색되어 왔으나, 재생골재는 주로 콘크리트 도로기층용과 구조물 됫채움재와 같은 저급재료로 사용되고 있다. 본 연구는 재생골재의 콘크리트 용 골재로의 효율적인 재활용 가능성을 위하여, 재생골재의 구성광물, 화학조성 및 공학적 물성 특성 파악하고 재생콘크리트(RCA)의 시공성과 역학적 특성에 대한 연구를 수행하였다. 재생골재에 잔존하는 폐 콘크리트의 모르타르 및 시멘트 페이스트는 골재의 기초 물성 특성, 재생콘크리트의 시공성 및 굳은 콘크리트의 공학적 특성에 주요한 영항을 미치는 것으로 나타났다. 그러나, 적절한 양의 재생굵은골재를 대체한 재생콘크리트는 압축강도와 동결융해 내구성에서 보통 콘크리트의 기준에 근접하는 것으로 나타났다 따라서, 재생골재의 제조과정에서 폐 콘크리트의 모르타르 및 시멘트 페이스트의 제거가 효율적으로 이루어지고 적절한 대체율이 적용되면, 재생골재는 콘크리트용 골재로서 효율적인 사용이 확대 될 수 있을 것으로 사료된다.

• 한국도로학회논문집
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• 제17권4호
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• pp.19-24
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• 2015

PURPOSES : The objective of this study is to evaluate the effect of the residual mortar of recycled concrete aggregate on the expansion behavior during alkali silica reaction (ASR). METHODS: In order to evaluate the net effect of residual mortar on ASR expansion behavior, two aggregate samples with the same original virgin aggregate source but different residual mortar volumes were used. ASTM C1260 test was used to evaluate the ASR expansion behavior of these two aggregates and the original virgin aggregate. RESULTS: The greater the amount of residual mortar in recycled concrete aggregates, the less is the induced ASR expansion. Depending on the amount of residual mortar in recycled concrete aggregate, the ASR expansion of recycled concrete aggregate may be less than half of that of the original virgin aggregate. CONCLUSIONS: The residual mortar of recycled concrete aggregate may lead to the under estimation of the ASR expansion behavior of the original virgin aggregate.

• 콘크리트학회논문집
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• 제14권3호
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• pp.307-314
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• 2002

천연골재 부족현상의 해소, 자원절약 및 환경보존 등의 목적으로 폐콘크리트를 재생골재로 재활용하기 위한 연구가 진행되고 있으나, 재생골재의 품질변동이 클 뿐만 아니라, 재생골재 사용 콘크리트의 역학적 성질이 보통콘크리트와 비교하여 다소 떨어지는 문제점이 지적되고 있다. 본 연구에서는 폐골재 사용 콘크리트의 동결음해 저항성을 파악하기 위하여 실시한 일련의 실험결과를 요약하면 다음과 같다. 모재 및 폐골재에 부착된 모르타르량의 다소에 따라 재생골재의 품질이 크게 좌우되므로 파쇄공정의 개선이 매우 중요한 과제로 생각된다. 재생골재 사용 콘크리트의 압축강도는 보통콘크리트와 비교하여 큰 차이가 없었으나, 염화물 이온 침투성은 재생골재에 부착된 모르타르량 때문에 보통콘크리트보다 크게 떨어짐을 알 수 있었다. 재생골재 사용 콘크리트의 동결융해 저항성은 재생골재에 부착된 모르타르의 연행공기량에 따라 크게 상이하였으며, NA 모재 및 폐골재 사용 콘크리트의 내구성지수는 보통콘크리트에 비하여 월등히 떨어졌으나, AA 모재골재 사용 콘크리트는 오히려 큰 값임을 알 수 있었다. 그러므로 재생골재 사용 콘크리트의 동결융해 저항성을 향상시키기 위해서는 적정량의 연행공기를 포함한 재생골재의 사용이 반드시 요망된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
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• pp.345-348
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• 2006

Along with recent improvement of recycling technique, the quality of the recycled concrete aggregate have become very competitive to the natural concrete aggregate. Therefore, a practical use of the recycled concrete aggregate may be possible for structural members. Majority studies about the recycled concrete aggregate was emphasized a limitation of fundamental study concerned with a strength characteristics and durability of the recycled aggregate concrete. Therefore, for the extension of application of recycled concrete aggregate, this investigation verifies the strength characteristics and structural performances of PHC piles used with coarce and fine recycled concrete aggregate.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.105-108
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• 2005

This study investigated fundamental properties of the recycled aggregate which was produced through recent hi-techniques of recycling. In addition, the mechanical properties of the concrete that used the recycled aggregate were compared to the concrete used the natural aggregate. From the results of the mechanical property tests, as the recycled aggregate replacement ratio increased, the compressive strength and elastic modulus decreased. When the recycled aggregate completely replaced the natural aggregate, the compressive strength and elastic modulus was about 15$\%$ and 35$\%$ lower than the natural aggregate concrete, respectively. Based on the test results, equations for prediction of compressive strength and elastic modulus were suggested in the consideration of the amount of the replaced recycled aggregate. Based on the test results and study, the equation predicting the required development length of the recycled aggregate concrete is proposed.