Mechanical, rheological, and durability analysis of self-consolidating concretes containing recycled aggregates

Hiwa Mollaei,Taleb Moradi Shaghaghi,Hasan Afshin,Reza Saleh Ahari,Seyed Saeed Mirrezaei 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.88 No.2

In the present paper, the effect of recycled aggregates on the rheological and mechanical properties of selfconsolidating concrete is investigated experimentally and numerically. Hence, the specimen with two types of recycled aggregates, i.e., known and unknown resistance origins, are utilized for the studied specimens. The experiments in this study are designed using the Box-Behnken method, which is one of the response surface methods. Input variables in mixtures include silica fume in the range of 5-15% as a percentage substitute for cement weight and recycled coarse and fine aggregates in the range of 0-50% for both series of recycled materials as a substitute for natural materials. The studied responses are slump flow, V funnel, compressive strength, tensile strength, and durability. The results indicate that the increase in the amount of recycled aggregates reduces the rheological and mechanical properties of the mixtures, while silica fume effectively improves the mechanical properties. In addition, the results demonstrate that the fine recycled aggregates affect the total response of the concrete significantly. The results of tensile and compressive strengths indicate that the mixtures including 50% recycled materials with known resistance origin demonstrate better responses up to 8 and 10% compared to the materials with unknown resistance origins, respectively. Recycled materials with a specific resistance origin also show better results than recycled materials with an unknown resistance origin. Durability test results represent those concretes containing recycled coarse aggregates have lower strength compared to recycled fine aggregates. Also, a series of mathematical relationships for all the responses are presented using variance analysis to predict mixtures’ rheological and mechanical properties.

택배 등 유통포장재의 재사용 활성화를 위한 정책 지원방안 마련 연구

이소라 ( Sora Yi ),임혜숙,김영희,신용승,윤영섭,박경북,오정아,이종원 한국환경연구원 2019 수시연구보고서 Vol.2019 No.-

The Korean government announced that the growing preference for online shopping in recent years has led to the increasing uses of packaging materials, such as cardboard boxes used in parcel delivery services. In 2017, domestic parcel deliveries increased by 13.3% from the previous year to 2.319 billion parcels, and annual usage of parcel deliveries was 44.8 times per capita. This trend points to the need to examine the possibilities for reducing and recycling packaging materials at the distribution and logistics stages, introducing reusable packaging materials, and investigating how such efforts can be supported through policy measures. This study prepares for the introduction of new packaging materials such as reusable packaging based on the analysis of domestic and international trends and case studies in logistic packaging materials. In conjunction, this study proposes plans for establishing a legal basis to promote reusable packaging materials based on a review of existing regulations and laws as well as management strategies for transitioning to a sharing system. In particular, this study focuses on tertiary packaging, that is, the packaging materials used for parcel delivery services. The comparison between growth trends in the estimated consumption of cardboard boxes for parcel deliveries and the volume of parcel deliveries in Korea reveals that the consumption of cardboard boxes shows a relatively slow increase against the rapid rise in parcel deliveries. This difference in growth trends may be attributed to the increased use of packaging materials other than cardboard boxes, e.g., plastic bags. Meanwhile, the volume of parcel deliveries and that of online shopping mall transactions show a proportional correlation where parcel deliveries increase with a sharp increase in online shopping mall transactions. The analysis of the volume of online shopping mall transactions also reveals a strong correlation between online shopping malls and the volume of parcel deliveries. In this context, this study categorized online shopping products into three groups based on the level of protection provided by their packaging materials (e.g., fragile products, perishable products). Products which were unlikely to be damaged in the delivery process such as books, clothes and accessories, and household products were categorized under Group A; perishable products, which need to be kept fresh throughout the delivery process, such as food and beverages, fresh produce (agricultural and fishery products), and packaged food were put under Group B; and fragile products which have a higher risk of damage during delivery such as computers, electronics, and IT products were classified as Group C. The volume of transactions for Group A products increased 15.1-19.8% year-on-year, while Group B products showed higher growth than the other groups with an increase of 29.8-57.8%, notably, 57.8% in 2017. This growth is mainly due to an increase in purchases of packaged food. Meanwhile, Group C products showed a year-on-year increase of 12.0-21.7%. The use of packaging materials in logistics in Korea are dealt with by the following laws and regulations: the Guideline for Reducing Logistic Packaging Materials (January 16, 2019); Article 9 (Control of Generation of Packing Wastes) and Article 10 (Control, etc. of Use of Disposable Products) of the Act on the Promotion of Saving and Recycling of Resources; the Rules on the Standards for the Materials and Methods of Packaging Products; Article 59 (Promotion of Eco-Friendly Logistics) of the Framework Act on Logistics Policies; and the Guidelines for Parcel Delivery of Frozen Foods (June 26, 2019). Article 9 of the Act on the Promotion of Saving and Recycling of Resources stipulates provisions to repress the generation of packaging waste, promote their recycling, and prevent unnecessary double packaging by limiting the number of times a product can be packaged and the space volume ratio of packaging. However, the standards for packaging materials and packaging methods are not applied to products intended for transportation, thus requiring an amendment to the law. In Korea, reusable logistic packaging materials are mainly circulated through a closed loop system. In other countries, however, open loop systems such as RePACK or hybrid loop systems such as the Loop Platform are in operation. In closed loop systems, packaging materials are designed according to specified size requirements and performance standards and are reused by charging a deposit fee and recollecting the packaging through a designated recollection system. However, it is difficult for other distributors to participate in existing closed loop systems. In the case of open loop systems that enable various distributors to enter and exit the system at any time, the reusable packaging materials need to be designed according to general size and performance requirements, thereby limiting their application to diverse product groups. However, open loop systems can be expanded the use of reusable packaging materials gradually by centering on distributors who sell similar product groups. A consumer awareness survey on reusable packaging materials revealed that the majority of consumers agreed to the environmental benefits of using reusable packaging materials (89.7%) and were favorable toward using reusable packaging materials (90.9%). 84.1% of the respondents said that they are willing to pay refundable deposit fees to facilitate the reuse of packaging materials. The amount of deposit fee by type of parcel packaging preferred by consumers was identified as 1,869 won for reusable parcel boxes (for electronics, etc.), 2,084 won for reusable cooling boxes or bags (for food products, etc.), and 1,450 won for reusable parcel bags (for clothing, etc.). 95.6% of the respondents viewed it possible to introduce reusable packaging materials. Consumers responded more negatively about the use of reusable packing materials for perishable products (29.7%) than fragile products (45.0%). Also, when asked to give suggestions to central and local governments, 44.8% of the respondents suggested strengthening relevant policies and regulations, followed by more campaigns and educational programs about reusing packaging materials (27.8%), and the implementation of recollection sites and packaging materials reuse systems (14.2%). As for practical ideas to reduce packaging waste, many of the respondents proposed the immediate return of packaging materials to the product seller through parcel delivery person, followed by the idea of providing consumers with the option to choose reusable packaging. According to the opinions of related experts such as those in academia, the establishment of a system for reusing parcel packaging materials can be highly effective in the case of Korea considering the high usage of parcel delivery services per capita compared to other countries. Since parcel packaging methods used in Korea’s logistics have a higher space volume ratio than those used overseas, the need to suppress over-packaging was highlighted. The suggestions from distribution and logistics industries included various efforts to promote the reuse of packaging materials as well as anticipated problems and areas which require governmental support. The criteria for assessing the eco-friendliness of packaging materials and their recycle and reuse potential may vary depending on the materials used (e.g., base materials and the materials used for bonding and cushioning, cooling materials, internal packaging materials, as well as the materials used for invoices), printing methods, and the functions of the packaging. The level of protection provided by the packaging should also be considered in the evaluation. Based on research, the suggested criteria for assessing the eco-friendliness of packaging materials that can satisfy the keywords of recycling and reuse are given in < Table 1 >. Eco-friendly packaging policies should place priority on reducing the generation of waste by restricting usage. Also important is to design packaging materials considering their reusability in each applicable aspect. For a sharing system of reusable packaging materials, it is vital to establish a system for each of the stages of disposal, collection, recovery processing, and redistribution and to determine the roles of the stakeholder at each stage. Various aspects need to be reviewed for the efficient operation of the deposit system for reusable packaging materials, such as the introduction of disposal fees for single-use packaging materials and incentives for each stakeholder involved in the system (manufacturer, distributor, consumer, etc.). This study proposes strategies for promoting the reuse of packaging materials in logistics in terms of 1) improvements in laws and regulations, 2) central and local government support, 3) industry participation, 4) consumer participation, and 5) technology development. 1) Improvements in laws and regulations There is a need to review Article 2 of the Rules on the Standards for the Materials and Methods of Packaging Products, which stipulates exceptions for products intended for transportation, and to prepare additional standards for products intended for transportation. If the policy directions of the Ministry of Environment and the Ministry of Food and Drug Safety are in conflict, industry stakeholders may become confused as to which policy direction to follow, e.g., the perspective of food safety or the environment. Thus, guidelines need to be improved through discussions between ministries. Also, measures to promote reduction and recycling as well as the reuse of packaging materials should be reviewed to prepare specific proposals. 2) Support from central and local government It is possible to promote the transition to reusable packaging materials through instructive guidelines or laws regulating the use of disposable packaging materials until the initial investment in manufacturing reusable packaging materials and constructing the infrastructure for their implementation is completed and a stable operation system is established. Financial incentives, such as tax incentives, can help reduce the burden on the industry to implement reusable packaging materials. The government may start with a pilot project which involves an industry based on voluntary agreements, then assess the applicability of the project and make necessary improvements for expanding the scope to other companies. 3) Industry participation The transition to a sustainable system for reusable packaging can be accomplished by reviewing and developing the requirements for packaging materials in terms of their eco-friendliness and the level of protection provided, etc., and by utilizing various marketing strategies and incentives for inducing consumer participation. In addition, the standardization of packaging materials will provide a foundation for more companies and a larger range of products to be a part of the system. 4) Consumer Participation For active consumer participation, economic support (i.e., incentives) and economic burden (i.e., deposit fees) should be utilized appropriately. Economic support can reward the consumers for their eco-friendly behavior, while economic burdens can induce the completion of participation in eco-friendly practices. 5) Development of technologies The development of technologies for resource recycling and eco-friendly packaging should be carried out through cooperation between packaging material manufacturers and the distributors and logistics companies that use such packaging materials, so that packaging materials are designed and manufactured based on the considerations of resource recycling and eco-friendliness throughout their full lifecycle (manufacture of packing materials ⇒ primary and secondary packaging ⇒ packaging for logistics ⇒ consumption ⇒ recycling and processing after disposal). In this regard, priority should be given to the development of technologies for reducing packaging waste, and afterward, technologies for recycling and reusing packaging materials.

재활용 섬유패션디자인에 나타난 조형적 특성 연구

양진숙(Jin Sook Yang),박효은(Hyo Eun Park) 한국디자인문화학회 2012 한국디자인문화학회지 Vol.18 No.1

현대 사회는 다양하게 변화함에 따라 섬유패션 시장은 다양한 트렌드가 공존하고 정형화된 아름다움보다 개성과 다양성을 중요시하고 있다. 1980년대 에콜로지 패션의 영향으로 등장한 재활용 섬유패션은 환경보존운동과 자원고갈 문제 등에 의해 활발해지면서 쓰레기와 폐기물이 작품의 소재 및 주제가 되었다. 또한, 실용성과 희소성, 예술성이 가미되면서 재활용 소재만의 조형적 특성을 만들었다. 본 연구는 이러한 흐름에 맞추어 재활용 섬유패션에 나타난 조형적 특성에 대해 분석하기 위해 2000년대 이후 발표된 재활용 섬유패션디자인 사진을 주요 인터넷 사이트에서 수집하였다. 수집 된 자료에서 원형 그대로 재활용한 작품위주로 조형적 특성을 분석함으로써 재활용 섬유패션의 가능성과 소재 및 디자인 영역을 넓히는데 목적이 있다. 연구결과는 다음과 같다. 재활용 섬유패션 디자인에 나타난 소재는 일상생활에서 볼 수 있는 쓰레기와 폐기물이었으며 본래의 모습 그대로 재사용하거나 해체하여 재구성되면서 재활용 섬유패션만의 특성을 만들어내고 있었다. 재활용 섬유패션디자인의 조형적 특성으로는 소재의 고정관념을 깨고 기계화되어가는 사회에 대해 비판하는 정크 리사이클 룩(Junk Recycle Look), 낡고 오래된 듯한 이미지를 전달하는 빈티지 리사이클 룩 (Vintage Recycle Look), 현대적인 감각과 실용성을 가지고 있는 컨템퍼러리 리사이클 룩(Contemporary Recycle Look), 예술적인 요소와 실험정신이 돋보이는 아르티장 리사이클 룩(Artisanal Recycle Look)으로 나타났다. 다양한 조형적 특성들을 통해 재활용 섬유패션이 현대 섬유패션과 차별화 된 디자인을 추구하면서 희소성과 실용성, 창의성을 가지고 자원절약과 환경보호에 대한 의지를 적극적으로 보여주고 있었다. 이러한 연구결과, 재활용 섬유패션디자인의 조형적 특성은 쓰레기와 폐기물이 소재로서의 가능성과 재활용 디자인만의 조형적 특성을 만듦으로 현대 섬유패션디자인과의 차별성을 가지고 있었으며 지구환경과 자원고갈 등에 대한 심리적 불안감과 메시지를 전달하여 사회적인 문제에 대해 적극적으로 생각하고 해결방안을 모색하고 있는 걸 알 수 있었다. 마지막으로 본 연구를 통해 섬유패션의 영역 확장과 재활용 소재의 발전 가능성, 섬유패션 디자인이 앞으로 나아갈 방향의 기초자료가 되길 기대한다. As modern society diversifies, individuality and diversity are being more appreciated than standardized beauty in textile fashion market, where various trends coexist. Recycled textile fashion emerged under the influence of ecology fashion in the 1980s. With the promotion of environmental protection and recognition of scarce resources, trash and wastes were introduced as the theme and materials of art works. Practicality, scarcity and artistry were combined to make up formative features unique to recycled materials. The objective of this study is to analyze formative features displayed in recycled textile fashion. In order to do so, photographs of recycled textile fashion design were collected from major internet web-sites published since 2000. By focusing on projects which kept the original forms of recycled materials and analyzing their formative characteristics, this research seeks to extend the potential of recycled textile fashion and diversity of its materials and design. The results of research showed that materials used in recycled textile fashion design were wastes that can be easily found in our daily lives. They were either used in its original forms or were disassembled and rearranged. Junk Recycle Look criticizes mechanization of the society and seeks to free itself from fixed form of materials. Vintage Recycle Look transfers worn out and faded images. Modern taste and practicality can be found from Contemporary Recycle Look. Lastly, Artisanal Recycle Look displays artistic elements with an experimental spirit. It was found that through various formative features, recycled textile fashion pursues new designs different from modern textile fashion. With scarcity, practicality and creativity in mind, recycled textile fashion actively exhibited its determination to save resources and protect environment. As the findings illustrated, the formative features of recycled textile fashion design lied in its potential to turn wastes and trash into usable materials. It differentiated itself from modern textile fashion design by delivering messages concerning the environment and scarce resources. Not only did it raise issues of society, but also committed itself to finding solutions. It is hoped that this study will be seen as valuable foundational resources, leading to a further development of textile fashion and recycled materials.

폐비닐 재활용을 위한 재생원료 분석 및 배합비율에 따른 특성 평가

안낙균,이찬기,김정환,박필환,김승환,윤진호 한국자원리싸이클링학회 2021 資源 리싸이클링 Vol.30 No.1

생활계에서 발생되는 폐비닐은 토사, 금속, 유리 등의 이물질로 인해 고형연료(SRF, Solid Refuse Fuel)로 사용되었지만 최근 환경문제로 인해 고형연료의 사용량이 감소하고 있어 재활용이 필요한 실정이다. 본 연구에서는 폐비닐 재활용을 위해 우선 생활계 폐비닐로 생산된 복합 재생원료와 영농폐비닐로 생산된 PE 단일 재생원료에 대해 분석을 진행하였다. 원료 분석 결과, 폐비닐은 주로 폴리에틸렌으로 이루어져 있고 복합 재생원료는 약 2%의 회분이 잔존하고 있으며 PE 단일 재생원료의 경우는 회분이 없는 것을 확인하였다. 또한 두재생원료의 배합비율에 따른 인장강도를 측정한 결과 열처리 온도 200 ℃, 압착 압력 30 MPa, 배합비율 3:7 (복합:PE 단일) 조건에서 인장강도가 최대 약 16 MPa임을 확인하였다. 굽힘강도는 열처리 온도 200 ℃, 압착 압력 30 MPa, 배합비율 3:7 (복합:PE 단일) 조건에서최대 약 39 MPa임을 확인하였다. 따라서 재생원료들의 배합비율에 따른 강도 특성 변화를 확인함으로써 폐비닐의 재활용 가능성을 제시하고자 하였다. Waste vinyl generated from household waste has been used as a solid refuse fuel (SRF) due to the presence of impurities such as soil, metal, and glass; however, the amount of SRF used has been decreasing owing to recent environmental problems, thereby necessitating the need for recycling. In this study, the mixed recycled raw material produced from household waste vinyl and polyethylene (PE) single recycled raw material produced from agricultural waste vinyl were examined. Raw material analysis revealed that waste vinyl was mainly composed of polyethylene, and approximately 2% of ash remained in the mixed recycled raw material, whereas no ash was found in the PE single recycled raw material. In addition, the analysis of tensile strength according to the mixing ratio of the two recycled raw materials revealed that the highest tensile strength was approximately 16 MPa under the heat treatment temperature of 200 °C, compression pressure of 30 MPa, and a mixing ratio of 3:7 (mixed:PE single). In addition, the highest bending strength was approximately 39 MPa under the heat treatment temperature of 200 °C, compression pressure of 30 MPa, and a mixing ratio of 3:7 (mixed:PE single). Therefore, the possibility of recycling waste vinyl was suggested by investigating the change in strength characteristics according to the mixing ratio of the recycled raw materials.

국내 건축 설계에서의 재활용재료 적용에 대한 연구

윤정원 한국문화공간건축학회 2017 한국문화공간건축학회논문집 Vol.- No.58

Understanding the concept of architectural materials with recycled contents should precede integrated design process with recycled building materials, making a building become an environment embodying the principle of sustainability. Therefore, firstly this study examines the scope and meaning of recycling through analysis of Korean and foreign studies and literatures. Following the conceptual redefinition of recycling considered in this study, the paper analyzes four building sustainability assessment tools including BREEAM, LEED, CASBEE and G-SEED, focusing on assessment criteria and evaluation parameters enabling practical application of materials with recycled contents. Because G-SEED includes use of green certified products to ensure use of recycled materials. Analysis of Good Recycled products and Eco-label products certified in available resource recycling is also performed based upon information provided in online product database. Subsequently, the limitations in applying materials with recycled contents for architectural design in Korea are discussed. The possibility of activating the application of architectural materials with recycled contents is identified by introducing case studies in foreign countries.

도로포장용 상온 재생 아스팔트 혼합물 개발

이종만,김낙석,김완상,홍은철 한국방재학회 2009 한국방재학회논문집 Vol.9 No.3

In order to use recycled aggregate as pavement base or subbase materials, the US and many other European countries have started research since the early 1980s. Korea also had a recycle idea as a plan for the vast amount of construction wastes due to the downtown renovation in the 1990s, but was not put into practical use. After the resources saving and recycle expedition law in 1994, wastes from construction sites that have more than a certain amount of construction budget were recycled as pavement base and subbase materials, but now, researches are being conducted to use them as paving materials. The use of construction wastes is meaningful in many ways. It helps the natural conservation and aggregate consumption, and also improves pavement performance. This research presents a development of cold-mixed reclaimed asphalt pavement materials using recycled aggregates. 순환골재를 도로의 기층재료나 보조기층용 골재로 활용하기 위하여 1980년대 초부터 미국과 유럽의 여러 나라에서 연구가 진행되었다. 우리나라에서도 1990년대 도심지 재개발 및 아파트 재건축의 증가로 건축폐기물이 다량으로 발생하여 이에 대한 대책을 마련하기 위한 방안으로 재활용 논의가 있었으나 실용화되지 못하였고 1994년 자원의 절약과 재활용 촉진에 관한 법률이 제정되어 일정 공사금액 이상의 건설사업자가 건설현장에서 배출되는 건설폐자재를 재활용화 하도록 규정한 이후에 구조물 채움재나 도로의 보조 기층재, 성토 및 복토용으로 활용되다가 최근에 포장재료로 활용하기 위한 연구가 수행되고 있다. 건설폐자재의 활용은 자원재활용과 함께 자연환경을 보호하고 부족한 골재난을 해소할 수 있으며 양질의 재료를 이용하여 포장의 공용성을 확보할 수 있어 여러 측면에서 효과적이다. 본 연구에서는 순환골재를 이용하여 자원을 재활용하고 에너지 소비를 절감할 수 있는 상온 재생 아스팔트 혼합물 개발을 위한 연구 수행결과를 정리 하였다.

송배전관로 되메움재로 활용하기 위한 국내 순환골재의 다짐 및 열적 특성 평가

위지혜,최항석,홍성연,이대수,박상우 한국지반공학회 2011 한국지반공학회논문집 Vol.27 No.7

Recently, the utilization of recycled aggregates for backfilling a power transmission pipeline trench has been considered due to the issues of eco-friendly construction and a lack of natural aggregate resource. It is important to identify the physical and thermal properties of domestic recycled aggregates that can be used as a backfill material. This paper evaluated thermal properties of concrete-based recycled aggregates with various particle size distributions. The thermal properties of the recycled aggregates and river sand provided by local vendors were measured using the transient hot wire method and the transient needle probe method after performing the standard compaction test. The needle probe method considerably overestimated the thermal resistivity of recycled aggregates especially at the dry of optimum water content because of experiencing disturbance while the needle probe is being inserted into the specimen. Similar to silica sand, the thermal resistivity of recycled aggregates decreased when the water content increased at a given dry density. Also, this paper evaluated some of the existing prediction models for the thermal resistivity of recycled aggregates with the experimental data, and developed a new prediction model for recycled aggregates. This study shows that recycled aggregates can be a promising backfill material substituting for natural aggregates when backfilling the power transmission pipeline trench.

폐기물의 성토재 재활용에 관한 환경법적 문제

박종원 한국환경법학회 2019 環境法 硏究 Vol.41 No.1

As part of the waste recycling policy, there has been considerable recycling of waste into soil as filling materials. However, a legal management system related to recycling wastes as filling materials was not established until just recently. As a result, there have been many cases in which recycling wastes as filling materials has led to soil contamination. On the one hand, can a competent authority issue an order to clean up the contaminated land under the Soil Environment Conservation Act (“SECA”), where the waste has been duly recycled as filling materials in accordance with the Wastes Control Act (“WCA”)? On the other hand, can a competent authority issue an order to take action for disposing of the waste that was illegally recycled as filling materials under the WCA, if the waste forms an integral part of the soil? As for the possibility of an order to clean up the contaminated land under the SECA, the “contaminated soil” whose level of contamination is found to exceed the worrisome level of soil contamination should be cleaned up under the SECA whether or not the legal recycling of the waste is the cause of soil contamination. Moreover, regarding the possibility of an order to take action against the disposal of waste under the WCA, the material should have been disposed of illegally and should be considered to be a “waste” based on the time the order was issued. It cannot be said that a material that was a waste in the past will be a waste permanently. The necessity that constitutes the main indication of the “waste” conception is necessarily variable. The Korean Supreme Court has consistently held that, even if a material was a waste in the past, if society approves the need for the material in the general sense, the material loses its properties as a waste from that time. Given these points, even if a material had the properties of a waste at the time of landfill, if it has been used as a filling material in processes such as mixing with other soil or physical mixing with the soil of the existing land to form part of the land and has started to perform normal functions as soil, it should be no longer be considered to be a waste. Therefore, it is not subject to the waste disposal order. 폐기물 재활용 정책의 일환으로 폐기물을 토양에 매립하는 일이 심심치 않게 이루어져 왔으나, 그에 대한 관리법제는 체계적이었다고 보기 어렵다. 그간 성토재, 복토재 등으로 폐기물의 재활용이 폭넓게 허용되어 왔으나, 얼마 전까지만 해도 「폐기물관리법」에 따른 재활용 기준이나 준수사항에서 토양에 대한 접촉으로 인한 토양오염의 가능성을 따로 고려하고 있지 않았었기 때문에, 폐기물의 성토재로의 재활용이 토양오염으로 이어지는 사례가 적지 않았다. 한편, 「폐기물관리법」과 「토양환경보전법」은 그 제정시기, 규율목적, 내용 등이 상이하고 양 법률 간의 적용관계가 명시되어 있지 아니하여 법 적용 현장에서 많은 혼란을 초래하고 있다. 특히, 과거 「폐기물관리법」에 따라 적법하게 성토재 등으로 재활용되었다가 그 후에 「토양환경보전법」에 따른 조사 결과 우려기준 초과 사실이 드러난 경우 이를 정화조치명령의 대상으로 할 수 있는가의 문제가 제기될 수 있다. 혹은 그 반대로 과거 「폐기물관리법」을 위반하여 불법적으로 성토재 등으로 재활용된 경우, 일정한 시간의 경과에 따라 해당 폐기물이 토양과 일체를 이루게 되었을 때 이를 폐기물처리조치명령의 대상으로 할 수 있는가의 문제도 제기될 수 있다. 이 글은 이와 같은 현실적인 문제에 있어서 어떻게 양 법률을 적용할 것인가에 관한 해석론을 제시하는 것을 목적으로 한다. 먼저 토양정화조치명령의 대상이 되는지 여부의 판단에 있어서는, 토양오염의 원인 행위가 무엇인지를 묻지 않고 「토양환경보전법」에 따른 토양오염물질이 그 우려기준을 초과한다면 ‘오염토양’에 해당하는 것이고 따라서 정화조치명령의 대상이 되는 것으로 보아야 할 것이다. 설령 해당 오염토양이 「폐기물관리법」 등의 관계법령에 따라 적법하게 성토재 등으로 재활용된 결과로서 발생한 것이라고 하더라도 달리 볼 것은 아니다. 다만, 경우에 따라서는 신뢰보호원칙 위반의 문제는 남게 될 것이다. 한편, 폐기물처리조치명령의 대상이 되는지 여부에 관해서는 폐기물의 불법 투기・매립 등과 같은 발동 요건에 해당하여야 함을 물론이고, 그 내용상으로 해당 폐기물을 적정하게 처리할 것을 명하기 위해서는 그 명령을 발령하는 시점을 기준으로 해당 물질이 ‘폐기물’로서의 성질을 갖추고 있어야 할 것이다. 한 번 폐기물이 영원한 폐기물인 것은 아니다. 폐기물 개념의 주요 징표를 이루는 ‘필요성’은 필연적으로 가변적이다. 이는 객관적으로 사람의 생활이나 사업활동에 필요하다고 사회통념상 승인될 정도에 이르렀다면 그 물질은 그 때부터 폐기물로서의 속성을 잃는다는 대법원의 확립된 태도를 통해서도 확인할 수 있다. 이에 더하여, 폐기물의 법적 개념 정의, 폐기물처리조치명령의 취지와 성질 및 요건・내용에 대한 해석, 폐기물과 토양의 구별 기준, 폐기물의 성토재 재활용 기준 등을 종합적으로 고려할 때, 설령 어떠한 물질이 매립될 당시에는 폐기물로서의 성질을 갖추고 있었고 또 당시의 재활용 기준에 맞지 않게 다른 토양과의 혼합 등의 과정을 거쳐 성토재로 사용되었다고 하더라도, 상당한 기간이 경과함에 따라 (i) 더 이상 오염된 상태가 아니고, (ii) 기존 토지의 흙과 물리적으로 분리할 수 없을 정도로 혼합되어 토지의 일부를 구성하게 되었고, (iii) 「폐기물관리법」상의 성토재 재활용 기준을 충 ...

상온 재활용 아스팔트 혼합물의 초기 상온양생 강도 발현을 위한 무기질 재료 반응특성 분석

김영민,최현준,류주열 한국도로학회 2018 한국도로학회논문집 Vol.20 No.6

PURPOSES: The object of this study is to select appropriate inorganic materials, and find the best mixing formula to secure fast curing time and enough initial strength, and then to evaluate the durability of the asphalt mixtures according to the degree of addition of the compound manufactured by the determined blending ratio. METHODS : The breaking time and reactivity between seven kinds of inorganic minerals, and the selected recycled aggregate and emulsified asphalt were compared to determine the best initial curing strength for the mixtures. Then, three inorganic materials were chosen as the materials that provide good breaking time and reactivity, and the best mixing formula for the three materials was determined. The chemical composition of the compound manufactured using the mixing formula was analyzed by energy dispersive x-ray system method. Finally, indirect tensile strength (ITS) test was performed (for two days) at room temperature to determine the proper amount of additives that will provide the best initial strength. RESULTS: From the results of the reactivity test, the best mixing formula (A:C:G = 60:30:10) for the three selected inorganic materials with short braking time and high reactivity was determined. The four types of cold reclaimed asphalt mixtures for ITS testing were manufactured by adding the inorganic material compounds at 0%, 3%, 5%, and 7%, and the ITS values were measured after two curing days. The ITS values at 5% and 7% were 0.308 MPa and 0.415 MPa, respectively. The results of quality control tests (Marshall stability, porosity, flow value, etc.) at 5% and 7% satisfied the specification criterion for the cold recycled asphalt mixtures. CONCLUSIONS : The selected inorganic materials (A, C, and G) and the best mixing formula (A:C:G = 60:30:10) accelerated the reaction with emulsified asphalt and shortened the curing time. Depending on the inorganic material used, the breaking time and reactivity can be directly related or unrelated. This is because of the chemical compositions of recycled aggregates, infiltrated foreign matter, and chemical reactions between the inorganic materials and other materials. Therefore, it is important to select the proper materials and the best mixing formula when evaluating the characteristics of the practically used materials such as recycled aggregates, inorganic materials, and emulsified asphalt.

Sustainable 3D printing with recycled materials: a review

Shivani Lodha,Bo Song,박상인,Hae-Jin Choi,Sang Won Lee,Hyung Wook Park,최승겸 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11

Combining recycling and additive manufacturing (AM) can bring significant environmental and economic advantages. Using recycled materials can help reduce waste and the need for virgin materials, which can be resource-intensive to extract and process. Recycling is also more energy-efficient than extracting and processing virgin materials. This paper reviews and discusses the current trends and limitations of using recycled materials for AM, an essential step toward a more sustainable manufacturing process. Specifically, this paper reviews the research on waste materials transformed into resins for stereolithography (SLA), digital light projection (DLP) printers, filaments for fused deposition modeling (FDM), as well as metal powders for selective laser melting (SLM) and selective laser sintering (SLS) printing processes. The goal is to provide an overview of the recycled materials used in AM, their recycling methods, and the mechanical and thermal properties of the resulting materials and manufactured parts. The paper also discusses potential improvements in the process and areas for future research.