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This paper presents simulations of different concentration plants that use Inert Construction and Demolition Waste as feed to generate coarse aggregates from old concretes. Different feed materials were studied: CDW generated in Spain; low-strength concretes, C16/20, which are ordinary concrete used in civil construction; and high-strength concretes, C50/60, from specific demolitions, such as old viaducts and bridges. Granulometric and densimetric analyses were performed, and the composition of the granulometric fractions of the proposed concretes were analyzed based on previous studies carried out, to understand the materials that can be recovered and considered for reinvestment in the market. Investment analysis considering the CAPEX, OPEX, revenue, IRR, MIRR, NPV, and DPP of the different concentrating plants with varying streams of concentration to recover the materials of interest (coarse aggregates) are presented and discussed. The results of the analyses indicate greater viability in plants that use mobile plants and the use of water jigs., Peer Reviewed, Postprint (published version)

The construction industry is a significant contributor to environmental issues, primarily due to the generation of substantial amounts of demolished concrete waste and CO2 emissions resulting from cement clinker production. Therefore, this study aims to assess the feasibility of recycling demolished concrete by-products (waste concrete powder and recycled concrete aggregates) into aggregates suitable for use in concrete mixes by utilizing active carbonation methods with flue gas use, an area that has been lacking in previous research. To conduct a detailed cost analysis, mathematical models based on Cost-Benefit Analysis with the Activity-Based Costing approach have been developed incorporating transportation, recycling, sequestration, and environmental costs based on the current and proposed state of Value Stream Mapping. To validate the feasibility and practicality of the developed models, a case study in Hong Kong has been conducted. The results of the study demonstrate an approximately 29 % greater economic efficiency of the proposed alternative concrete waste recycling method compared to the traditional approach. In the alternative method of concrete waste carbonization using flue gas, there is a significant reduction in the environmental cost of over 51 %, primarily attributed to the decreased reliance on commercially sourced CO2. Furthermore, the ability of waste concrete powder to sequester CO2 generates additional benefits, promoting sustainable recycling. These findings provide valuable insights into the potential for enhancing sustainability in construction material cycles. © 2024 Institution of Chemical Engineers

Reutilisation of the construction and demolition (C&D) wastes as aggregate in concrete is a vital step towards sustainability as it prevents depletion of natural resources as well as alleviates wastes. However, the attached mortar on the aggregate surface renders certain shortcomings like excessive water absorption, high porosity, and weak interfaces. Recycled aggregates can be treated to improve these shortcomings. However, the minimisation of the drawbacks involves huge energy, materials, and cost. Moreover, the efficacy of such adopted method is sometime questionable, and which needs further research. This study demonstrates bio-treatment of recycled coarse aggregate (RCA) as a means of upcycling and compares it with conventional cement slurry treatment. A novel spraying technique has been applied that significantly economises biocement treatment. The experimental results show that biocement treatment reduced the water absorption by 70%. The treatment has filled the pores of RCA and has prevented water absorption. In contrast, cement slurry coating treatment shows increase in water absorption of RCA by 19%. The compressive strength of concrete with 100% biocement treated RCA surpasses that of concrete with natural coarse aggregates. The genesis of this dramatic improvement in case of biocement has been established through micro-scale studies including scanning electron microscopy and energy-dispersive X-ray spectroscopy. The cost analysis demonstrates that RCA upcycled with biocement treatment is more economical than natural aggregates or cement treated ones. Findings of the present study led to the conclusion that 100% replacement of natural coarse aggregates can be achieved by upcycling C&D wastes as coarse aggregate through bio-treatment.

Over the last few years, the construction sector has experienced increasing demand for raw materials due to the rapid growth of the urban population. At the same time, most of the post-war buildings in Europe have reached the end of their service life. As a consequence, a period of intense demolition activities with significant waste generation is expected in the upcoming years. Both situations are eventually translated into significant environmental pressure. Concrete is the main component in construction and demolition waste (C&DW). Due to the high environmental footprint of this material, it is crucial to eliminate its consumption through recycling and re-use. Currently, concrete rubbles are crushed with regular crushers and used mainly for low-grade applications (down-cycling) such as road foundations. Despite the environmental and financial benefits, this practice is still not at a sustainable level since raw materials are still needed for new structures, while the demand for low-quality secondary materials in the construction sector has already declined. Two innovative recycling technologies called C2CA and Smart crushing (SC) developed recently in the Netherlands, aiming to close the material loop in the construction sector. These technologies recover most of the original concrete materials at high-quality, which can be use in the production of new concrete at higher rates than traditionally. This research focuses on the environmental and financial implications of the novel C2CA and SC recycling systems as alternative solutions to the Traditional crushing (TC) method. The evaluation was conducted based on an integrated LCA&LCC analysis framework in which the monetised environmental impacts (shadow costs) were internalised in the actual costs occurred within the supply chain of recycled concrete (production of primary materials, recycling, transports). On this basis, the recycling systems were compared from two different perspe, Civil Engineering | Building Engineering - Structural Design

This paper concerns the deconstruction of buildings as an alternative for demolition. Deconstruction has environmental, social and economic benefits since it allows the reuse of existing materials. Reuse within the construction industry has the potential to reduce waste streams while decreasing the demand for excavation of natural resources. The paper proposes a system for reusing in-situ concrete in new construction. For that, it provides a first exploration of the various aspects pertaining to such a system. As the preliminary findings show that the phase of cutting is technically viable, an estimation of possible energy saving is made. The analysis compares energy consumption of cutting methods for reuse in comparison with common recycling methods. This estimation tests whether the proposed method is favorable in terms of energy. The conclusion is that further research and testing are required in order to determine the feasibility of the system as a whole and the conditions and effects if coming into practice. Furthermore, a standard method for reuse must be developed in order to introduce the system to the market. Keywords: deconstruction, concrete deconstruction, concrete reuse, concrete recycling

RE:Concrete

As the construction sector is shifting towards circular economy models, the role of mineral construction materials as main waste fraction in terms of volumes is crucial. A characterization of this mineral stock, as well as the waste derived from it is decisive in ensuring the application of the best practices of circular economy. This paper describes a methodology for assessing the mineral building stock through a combination of geospatial and image analysis. By analysing old topographic maps, buildings are grouped according to their building age into different typologies and based on these maps the construction and demolition activity is evaluated. The mineral stock is assessed and estimations of the mineral construction and demolition waste (CDW) is generated for different stochastic scenarios. This methodology is applied exemplarily on the country of Luxembourg. It was found that the total mineral construction stock for Luxembourg is 276.75 Mt and has been growing at a rate of 20.81% to 24.39% in the last 30 years. Furthermore, the study identified a mean age of the urban building stock of about 60 years and a typical maximum building lifetime of 122 years. Based on the stochastic projections the mineral CDW generated from the existing building stock is expected to be up to 226.9 Mt by 2100, while if future building scenarios are considered, it can be as high as 885.3 Mt. The annual CDW production is expected to be sufficient for a viable concrete recycling activity if regulations on the waste volume flows are made available.

As the construction sector is shifting towards circular economy models, the role of mineral construction materials as main waste fraction in terms of volumes is crucial. A characterization of this mineral stock, as well as the waste derived from it is decisive in ensuring the application of the best practices of circular economy. This paper describes a methodology for assessing the mineral building stock through a combination of geospatial and image analysis. By analysing old topographic maps, buildings are grouped according to their building age into different typologies and based on these maps the construction and demolition activity is evaluated. The mineral stock is assessed and estimations of the mineral construction and demolition waste (CDW) is generated for different stochastic scenarios. This methodology is applied exemplarily on the country of Luxembourg. It was found that the total mineral construction stock for Luxembourg is 276.75 Mt and has been growing at a rate of 20.81% to 24.39% in the last 30 years. Furthermore, the study identified a mean age of the urban building stock of about 60 years and a typical maximum building lifetime of 122 years. Based on the stochastic projections the mineral CDW generated from the existing building stock is expected to be up to 226.9 Mt by 2100, while if future building scenarios are considered, it can be as high as 885.3 Mt. The annual CDW production is expected to be sufficient for a viable concrete recycling activity if regulations on the waste volume flows are made available.

In accordance with the Paris Agreement and the national goal of climate neutrality by 2045, Sweden needs to lower its greenhouse gas emissions. The second-largest source of CO2 emissions in the country comes from the production of cement, one of the main ingredients of concrete. With concrete being an ideal construction material, and Sweden needing to build more urban housing, Sweden is now in a position where they need to combine a high rate of housing construction with emission cuts to reach the climate goals. Concrete from construction and demolition waste is recyclable and can be used as an aggregate in new concrete and as an input in cement production. This is, however, currently not being done in Sweden and concrete waste is instead used for low-grade purposes such as road construction, landfill infrastructure, and backfilling. This study, therefore, aims to identify why recycled concrete is not being used to a larger extent in Swedish housing. An interview study has been conducted with actors along the concrete value chain to find out the extent to which housing projects use recycled concrete today, as well as what challenges and possibilities there are for increased use. The results show that recycled concrete within housing projects is currently only used for backfilling. Sweden does not have big enough volumes of high-quality concrete waste for it to be commercially viable to recycle it into recycled aggregate concrete. This recycling process is both costlier and more time-consuming than using conventional methods with raw materials, something Sweden has an abundance and easy access to. There is also a reluctance within the construction industry to use new and unproven methods and materials. Improved on-site sorting of waste materials, leading to higher quality aggregates, and construction standards adapted to the use of recycled materials, are actions to be taken to allow for an increased use of recycled aggregate concrete. All interviewed actors also me

RE:Concrete

This paper concerns the deconstruction of buildings as an alternative for demolition. Deconstruction has environmental, social and economic benefits since it allows the reuse of existing materials. Reuse within the construction industry has the potential to reduce waste streams while decreasing the demand for excavation of natural resources. The paper proposes a system for reusing in-situ concrete in new construction. For that, it provides a first exploration of the various aspects pertaining to such a system. As the preliminary findings show that the phase of cutting is technically viable, an estimation of possible energy saving is made. The analysis compares energy consumption of cutting methods for reuse in comparison with common recycling methods. This estimation tests whether the proposed method is favorable in terms of energy. The conclusion is that further research and testing are required in order to determine the feasibility of the system as a whole and the conditions and effects if coming into practice. Furthermore, a standard method for reuse must be developed in order to introduce the system to the market. Keywords: deconstruction, concrete deconstruction, concrete reuse, concrete recycling

In accordance with the Paris Agreement and the national goal of climate neutrality by 2045, Sweden needs to lower its greenhouse gas emissions. The second-largest source of CO2 emissions in the country comes from the production of cement, one of the main ingredients of concrete. With concrete being an ideal construction material, and Sweden needing to build more urban housing, Sweden is now in a position where they need to combine a high rate of housing construction with emission cuts to reach the climate goals. Concrete from construction and demolition waste is recyclable and can be used as an aggregate in new concrete and as an input in cement production. This is, however, currently not being done in Sweden and concrete waste is instead used for low-grade purposes such as road construction, landfill infrastructure, and backfilling. This study, therefore, aims to identify why recycled concrete is not being used to a larger extent in Swedish housing. An interview study has been conducted with actors along the concrete value chain to find out the extent to which housing projects use recycled concrete today, as well as what challenges and possibilities there are for increased use. The results show that recycled concrete within housing projects is currently only used for backfilling. Sweden does not have big enough volumes of high-quality concrete waste for it to be commercially viable to recycle it into recycled aggregate concrete. This recycling process is both costlier and more time-consuming than using conventional methods with raw materials, something Sweden has an abundance and easy access to. There is also a reluctance within the construction industry to use new and unproven methods and materials. Improved on-site sorting of waste materials, leading to higher quality aggregates, and construction standards adapted to the use of recycled materials, are actions to be taken to allow for an increased use of recycled aggregate concrete. All interviewed actors also me

RE:Concrete

Sampaio, C.H. et al., Demolished concretes recycling by the use of pneumatic jigs, Waste management and research, 38 (4) pp. 392-399. Copyright © 2020. DOI: 10.1177/0734242X20902835., Large quantities of construction and demolition waste is generated annually around the world. Part of this material is processed in recycling plants. After removing metals, fines and lights, the construction and demolition waste is crushed and sized and can be used as aggregates for low resistance concrete, for road sub-base, city landfill and other low value-added applications. For their use as coarse aggregate in structural concretes, construction and demolition waste must exhibit high densities and regularity of the material. This material usually is presented in demolished concretes. About 20% of the particles from demolished concretes can be used as coarse aggregates substituting part of natural aggregates in structural concretes. This article presents studies of demolished concretes recycling by the use of a pneumatic jig. All jigging tests were carried out with three different concretes produced in three strength classes: C16/20, ordinary concrete; C50/60, high strength concrete; and C70/85, very high strength concrete. Based on density distribution of the three concretes, there are reasonable masses with densities over 2.7¿g¿cm-3, particle density considered appropriate to the used as coarse aggregate for structural concretes. The concretes present different mass recoveries of the denser particles (different liberation). Coarse aggregates can be recovered with reasonable masses by the use of air jigs: About 65% for high strength concretes and about 75% for the low strength concrete. The jigging concentration efficiency depends on the concrete liberation, density and size distribution., The authors would like to thank the Brazilian National Council for Scientific and Technological Development (CNPq) for financial support. We are also very thankful to NORIE (Núcleo Orientado para a Inovação da Edificação), LEME (Laboratório de Ensaios Estruturais) and LEAMET (Laboratório de Estudos Ambientais para Metalurgia), research groups of the Federal University of Rio Grande do Sul, Brazil, where production and characterization of the concrete samples were carried out., Peer Reviewed, Postprint (author's final draft)

Currently, natural resources are consumed at an alarming rate than their production (United Nations Environment Programme, 2014). This imposes unprecedented pressure on the environment. The problem seems to get worse with the present increase in population and demand for infrastructures. To alleviate these and other related problems, a circular approach to construction material flow is crucial. Recycling construction and demolition wastes (C&DW) to generate high-quality materials is essential to ensure materials circularity in the construction sector. This article, therefore, describes the development of two large-scale technologies called Advanced Dry Recovery (ADR) and Heating Air classification System (HAS). ADR and HAS are industrial-scale technologies aimed to recycle End-of-Life (EoL) concrete into coarse, fine and ultrafine particles. While ADR is used to sort out clean coarse aggregates, HAS is used to produce clean fine aggregates by heating and separating the ultrafine hydrated cement components. The process parameters and the quality of aggregates are briefly described. Accordingly, concrete made of recycled coarse and fine aggregates displays comparable mechanical properties as the reference concrete which is made of natural aggregates. Both technologies are designed to be mobile so that EoL concrete wastes are processed at the site of demolition or close to ready-mix concrete plants, reducing the heavy traffic related to construction activities. These technologies, in general, have a potential in increasing sustainability and thereby greening the construction sector. This is by far a convenient contribution towards sustainable development and a big step towards closing the recycling loop in the construction sector., Resources & Recycling

RE:Concrete

Concrete is the most widely used artificial material, and shapes the largest area of the built environment in the Netherlands. Its waste stream is responsible for the highest percentage of construction and demolition waste and fundamental knowledge for affordable high-grade applications from old concrete has already been introduced. More precisely, the development of technologies that can separate End-of-life (EoL) concrete into its constituents, facilitates its recycling and reuse into new building materials and not in low-quality applications. However, in terms of concrete recycling, there is insufficient communication of the novel technologies in the construction sector and supply chain systems are not introduced in real-world problems. The current research focuses on a closed-loop approach concerning the production of conventional concrete based on a supply chain design. Specifically, the conventional and closed-loop supply chain of the production of concrete are designed in accordance with the SCOR Model. The main differences are identified and a ‘Concrete-to-concrete Recycling Plant’ is proposed as a solution to the EoL problem. It argues to change completely the conventional supply chain of concrete, and therefore recommendations for its future location in an urban environment are given. Additionally, a calculation tool regarding the recycling plant is developed in order to evaluate the suggested solution. The present study demonstrates that for each category of concrete, either prefabricated or site-cast, a recycling plant should be located next to the prefabricated or mortar industry in order to diminish transportation and inventory costs, as well as take advantage of the operating speeds of the novel technologies that compose the plant. Results indicate that a recycling plant is in accordance with the current market conditions and constitutes an efficient solution to the EoL concrete treatment by making concrete a circular material. Further research is req, Management of Technology (MoT)

The increasing volume of Construction and demolition waste (CDW) associated with economic growth is posing challenges to the sustainable management of the built environment. The largest fraction of all the CDW generated in the member states of the European Union (EU) is End-of-life (EOL) concrete. The most widely applied method for EOL concrete recovery in Europe is road base backfilling, which is considered low-grade recovery. The common practice for high-grade recycling is wet process that processes and washes EOL concrete into clean coarse aggregate for concrete manufacturing. It is costly. As a result, a series of EU projects have been launched to advance the technologies for high value-added concrete recycling. A critical environmental and economic evaluation of such technological innovations is important to inform decision making, while there has been a lack of studies in this field. Hence the present study aimed to assess the efficiency of the technical innovations in high-grade concrete recycling, using an improved eco-efficiency analytical approach by integrating life cycle assessment (LCA) and life cycle costing (LCC). Four systems of high-grade concrete recycling were analyzed for comparison: (i) business-as-usual (BAU) stationary wet processing; (ii) stationary advanced dry recovery (ADR); (iii) mobile ADR; (iv) mobile ADR and Heating Air Classification (A&H). An overarching framework was proposed for LCA/LCC-type eco-efficiency assessment conforming to ISO standards. The study found that technological routes that recycle on-site and produce high-value secondary products are most advantageous. Accordingly, policy recommendations are proposed to support the technological innovations of CDW management., Resources & Recycling

The increasing volume of Construction and demolition waste (CDW) associated with economic growth is posing challenges to the sustainable management of the built environment. The largest fraction of all the CDW generated in the member states of the European Union (EU) is End-of-life (EOL) concrete. The most widely applied method for EOL concrete recovery in Europe is road base backfilling, which is considered low-grade recovery. The common practice for high-grade recycling is wet process that processes and washes EOL concrete into clean coarse aggregate for concrete manufacturing. It is costly. As a result, a series of EU projects have been launched to advance the technologies for high value-added concrete recycling. A critical environmental and economic evaluation of such technological innovations is important to inform decision making, while there has been a lack of studies in this field. Hence the present study aimed to assess the efficiency of the technical innovations in high-grade concrete recycling, using an improved eco-efficiency analytical approach by integrating life cycle assessment (LCA) and life cycle costing (LCC). Four systems of high-grade concrete recycling were analyzed for comparison: (i) business-as-usual (BAU) stationary wet processing; (ii) stationary advanced dry recovery (ADR); (iii) mobile ADR; (iv) mobile ADR and Heating Air Classification (A&H). An overarching framework was proposed for LCA/LCC-type eco-efficiency assessment conforming to ISO standards. The study found that technological routes that recycle on-site and produce high-value secondary products are most advantageous. Accordingly, policy recommendations are proposed to support the technological innovations of CDW management., Resources & Recycling

Concrete is the most widely used artificial material, and shapes the largest area of the built environment in the Netherlands. Its waste stream is responsible for the highest percentage of construction and demolition waste and fundamental knowledge for affordable high-grade applications from old concrete has already been introduced. More precisely, the development of technologies that can separate End-of-life (EoL) concrete into its constituents, facilitates its recycling and reuse into new building materials and not in low-quality applications. However, in terms of concrete recycling, there is insufficient communication of the novel technologies in the construction sector and supply chain systems are not introduced in real-world problems. The current research focuses on a closed-loop approach concerning the production of conventional concrete based on a supply chain design. Specifically, the conventional and closed-loop supply chain of the production of concrete are designed in accordance with the SCOR Model. The main differences are identified and a ‘Concrete-to-concrete Recycling Plant’ is proposed as a solution to the EoL problem. It argues to change completely the conventional supply chain of concrete, and therefore recommendations for its future location in an urban environment are given. Additionally, a calculation tool regarding the recycling plant is developed in order to evaluate the suggested solution. The present study demonstrates that for each category of concrete, either prefabricated or site-cast, a recycling plant should be located next to the prefabricated or mortar industry in order to diminish transportation and inventory costs, as well as take advantage of the operating speeds of the novel technologies that compose the plant. Results indicate that a recycling plant is in accordance with the current market conditions and constitutes an efficient solution to the EoL concrete treatment by making concrete a circular material. Further research is req, Management of Technology (MoT)

Betong är idag och har länge varit det allra vanligaste byggnadsmaterial i Sverige. Det är ett robust och mångsidigt byggnadsmaterial med flera fördelar. Detta arbete är en experimentell studie av betongavfall från Hedareds sand & betong för betongprogrammet RE: Concrete och Högskolan i Borås. Betongavfallet krossas till ny ballast och därefter siktas och gjuts till ny betong enligt olika betongrecept. Försöken sker i betonglabbet i Högskolan i Borås för att krossa och tillverka betong. Grundreceptet har tillhandhållits av Hedareds sand & betong. Syftet med arbetet har varit att undersöka möjligheterna för att kunna använda återvunnen betong i nya bärande konstruktioner. Målet var att bevisa att det var tekniskt möjligt att åstadkomma en 100 % ersättning av ballast med återvunnen betong och få fram ny betong som passar den bärande stommen i en byggnad. Olika egenskaper undersöktes så som tryckhållfasthet för den nya betongen och partikelfördelning samt vattenabsorption för ballasten med målet att uppnå likvärdigt resultat som för referensbetongen. Resultatet visar att det är möjligt att kunna återvinna betong till 100 %. Arbetbarheten är bra i flertal försök men bör förbättras för att uppnå likvärdig arbetbarhet som referensbetongens. Referensbetongens tryckhållfasthet är 59 MPa och bästa tryckhållfasthet som erhållits för återvunnen betong är 57,2 MPa. Detta tyder på ett positivt resultat och den återvunna betongen i denna studie kan ersätta naturgrusballast i en bärande konstruktion till 100 %., Concrete is and has been for a long time the most common building material in Sweden. It is a robust and multipurpose building material with several advantages. This report is about an experimental study of concrete waste from Hedareds sand & betong. The concrete waste is crushed to a new aggregate and then sifted and casted into new concrete. The study was conducted in the Concrete Laboratory at University of Borås for crushing and casting of concrete. Recipes are supplied by Hedareds sand & betong as a starting point, which is later modified gradually to achieve better results. The purpose of this study is to investigate the possibilities for using recycled concrete in new constructions. It is also examined if the recycled concrete is technically sustainable and if the workability is good enough for using in load bearing structures. Different properties are studied such as compressive strength, particle distribution, water absorption and workability to achieve equivalent results as the reference concrete. The result obtained in this study shows that it is possible to recycle concrete by replacing aggregates to 100 % in new concrete. Workability is good in several tests, but it should be improved to achieve the same workability as the reference concrete. The reference concrete's compressive strength is 59 MPa and the best compressive strength obtained for recycled concrete is 57.2 MPa. This indicates positive results and the recycled concrete in this study can replace ordinary concrete in a load bearing construction.

Betong är idag och har länge varit det allra vanligaste byggnadsmaterial i Sverige. Det är ett robust och mångsidigt byggnadsmaterial med flera fördelar. Detta arbete är en experimentell studie av betongavfall från Hedareds sand & betong för betongprogrammet RE: Concrete och Högskolan i Borås. Betongavfallet krossas till ny ballast och därefter siktas och gjuts till ny betong enligt olika betongrecept. Försöken sker i betonglabbet i Högskolan i Borås för att krossa och tillverka betong. Grundreceptet har tillhandhållits av Hedareds sand & betong. Syftet med arbetet har varit att undersöka möjligheterna för att kunna använda återvunnen betong i nya bärande konstruktioner. Målet var att bevisa att det var tekniskt möjligt att åstadkomma en 100 % ersättning av ballast med återvunnen betong och få fram ny betong som passar den bärande stommen i en byggnad. Olika egenskaper undersöktes så som tryckhållfasthet för den nya betongen och partikelfördelning samt vattenabsorption för ballasten med målet att uppnå likvärdigt resultat som för referensbetongen. Resultatet visar att det är möjligt att kunna återvinna betong till 100 %. Arbetbarheten är bra i flertal försök men bör förbättras för att uppnå likvärdig arbetbarhet som referensbetongens. Referensbetongens tryckhållfasthet är 59 MPa och bästa tryckhållfasthet som erhållits för återvunnen betong är 57,2 MPa. Detta tyder på ett positivt resultat och den återvunna betongen i denna studie kan ersätta naturgrusballast i en bärande konstruktion till 100 %., Concrete is and has been for a long time the most common building material in Sweden. It is a robust and multipurpose building material with several advantages. This report is about an experimental study of concrete waste from Hedareds sand & betong. The concrete waste is crushed to a new aggregate and then sifted and casted into new concrete. The study was conducted in the Concrete Laboratory at University of Borås for crushing and casting of concrete. Recipes are supplied by Hedareds sand & betong as a starting point, which is later modified gradually to achieve better results. The purpose of this study is to investigate the possibilities for using recycled concrete in new constructions. It is also examined if the recycled concrete is technically sustainable and if the workability is good enough for using in load bearing structures. Different properties are studied such as compressive strength, particle distribution, water absorption and workability to achieve equivalent results as the reference concrete. The result obtained in this study shows that it is possible to recycle concrete by replacing aggregates to 100 % in new concrete. Workability is good in several tests, but it should be improved to achieve the same workability as the reference concrete. The reference concrete's compressive strength is 59 MPa and the best compressive strength obtained for recycled concrete is 57.2 MPa. This indicates positive results and the recycled concrete in this study can replace ordinary concrete in a load bearing construction.

The C2CA concrete recycling process consists of a combination of smart demolition, gentle grinding of the crushed concrete in an autogenous mill, and a novel dry classification technology called ADR to remove the fines. The` main factors in the C2CA process which influence the properties of Recycled Aggregates or Recycled Aggregate Concrete (RAC) include the type of Parent Concrete (PC), the intensity of autogenous milling and ADR cutsize point. This study aims to investigate the influence of PC and intensity of the autogenous milling on the quality of the produced recycled aggregates. Three types of concrete which are frequently demanded in the Dutch market were cast as PC and their fresh and hardened properties were tested. After near one year curing of PC samples, they were recycled independently while the aforementioned recycling factors were varied. The effects of different recycling variables on the water absorption, density, crushing resistance and durability of produced recycled aggregates were investigated. According to the results, type of the parent concrete is the predominant factor influencing the properties of the recycled aggregates. Milling intensity was found to be effective on improving the properties of recycled aggregates coming from weaker parent concrete. The experimental results suggest that among various milling intensities, milling at medium shear and medium compression improves the overall quality of RA.

Production of waste materials, via industrial and human activities, creates big environmental and economic problems but also opportunities to recover valuable resources. EU28 currently generates 461 million tons per year of ever more complex Construction and Demolition Waste (CDW) with average recycling rates of around 46%. There is still a significant loss of potential valuable minerals, metals and organic materials all over Europe. Considering the fact that public and private sectors have become aware of the urgency and importance of CDW recycling, the European Commission has taken initiatives towards sustainable treatment and recycling of CDW funding three tandem projects focusing on the development of an innovative and sustainable concrete recycling process. To that end, this article will firstly present the main achievements and ongoing activities for developing the innovative concrete recycling technology in the course of the EU C2CA, HISER and VEEP projects. In addition some figures related to the cost of each recycling unit process and the selling price of the recycled products are presented.

Production of waste materials, via industrial and human activities, creates big environmental and economic problems but also opportunities to recover valuable resources. EU28 currently generates 461 million tons per year of ever more complex Construction and Demolition Waste (CDW) with average recycling rates of around 46%. There is still a significant loss of potential valuable minerals, metals and organic materials all over Europe. Considering the fact that public and private sectors have become aware of the urgency and importance of CDW recycling, the European Commission has taken initiatives towards sustainable treatment and recycling of CDW funding three tandem projects focusing on the development of an innovative and sustainable concrete recycling process. To that end, this article will firstly present the main achievements and ongoing activities for developing the innovative concrete recycling technology in the course of the EU C2CA, HISER and VEEP projects. In addition some figures related to the cost of each recycling unit process and the selling price of the recycled products are presented., Materials and Environment

The Master's programme Industrial Ecology is jointly organised by Leiden University and Delft University of Technology. - Two main features of the construction and demolition systems translate into environmental pressure; an increasing need for building materials, to provide and maintain the infrastructure for growing urban populations, and the management of large amounts of waste streams that come from demolition and construction activities. Because of its high volume and limited management alternatives, the concrete waste is a critical stream. In the Netherlands, 95% of concrete rubble from construction and demolition waste is recycled into an application of lower grade through regular crushing. Alternative methods for reintegrating the coarse fraction into new concrete are Advanced Dry Recovery (ADR), electrical fragmentation (EF) and wet processing. Around 2% of the concrete waste stream is wet processed, but this alternative is energy intensive and expensive. Oppositely, ADR and EF are simpler technologies that also offer to retrieve the value of concrete, but are still at a pilot stage. This research project focuses on ADR as a recycling alternative to regular crushing in specific scenarios, addressing financial and environmental implications through the use of Life Cycle Assessment (LCA) and Life Cycle Costing (LCC). The main research question is: What are the environmental and economic implications of different concrete recycling scenarios in the Netherlands? The applicability of the results is that of a first estimate of the economic and environmental implications of shifting to ADR concrete-rubble recycling, with a detailed coverage of costs and types of environmental interventions. The research question is addressed from two different perspectives. First, a case study from the HISER project, sponsored by the European Union, is evaluated integrating LCA and LCC. The case is about the demolition of an end-of-life building and the construction of a new build, Technology, Policy and Management, Engineering Systems and Services; Values, Technology and Innovation, Industrial Ecology Joint degree Leiden & Delft

The C2CA concrete recycling process consists of a combination of smart demolition, gentle grinding of the crushed concrete in an autogenous mill, and a novel dry classification technology called ADR to remove the fines. The` main factors in the C2CA process which influence the properties of Recycled Aggregates or Recycled Aggregate Concrete (RAC) include the type of Parent Concrete (PC), the intensity of autogenous milling and ADR cutsize point. This study aims to investigate the influence of PC and intensity of the autogenous milling on the quality of the produced recycled aggregates. Three types of concrete which are frequently demanded in the Dutch market were cast as PC and their fresh and hardened properties were tested. After near one year curing of PC samples, they were recycled independently while the aforementioned recycling factors were varied. The effects of different recycling variables on the water absorption, density, crushing resistance and durability of produced recycled aggregates were investigated. According to the results, type of the parent concrete is the predominant factor influencing the properties of the recycled aggregates. Milling intensity was found to be effective on improving the properties of recycled aggregates coming from weaker parent concrete. The experimental results suggest that among various milling intensities, milling at medium shear and medium compression improves the overall quality of RA.

Production of waste materials, via industrial and human activities, creates big environmental and economic problems but also opportunities to recover valuable resources. EU28 currently generates 461 million tons per year of ever more complex Construction and Demolition Waste (CDW) with average recycling rates of around 46%. There is still a significant loss of potential valuable minerals, metals and organic materials all over Europe. Considering the fact that public and private sectors have become aware of the urgency and importance of CDW recycling, the European Commission has taken initiatives towards sustainable treatment and recycling of CDW funding three tandem projects focusing on the development of an innovative and sustainable concrete recycling process. To that end, this article will firstly present the main achievements and ongoing activities for developing the innovative concrete recycling technology in the course of the EU C2CA, HISER and VEEP projects. In addition some figures related to the cost of each recycling unit process and the selling price of the recycled products are presented.

Production of waste materials, via industrial and human activities, creates big environmental and economic problems but also opportunities to recover valuable resources. EU28 currently generates 461 million tons per year of ever more complex Construction and Demolition Waste (CDW) with average recycling rates of around 46%. There is still a significant loss of potential valuable minerals, metals and organic materials all over Europe. Considering the fact that public and private sectors have become aware of the urgency and importance of CDW recycling, the European Commission has taken initiatives towards sustainable treatment and recycling of CDW funding three tandem projects focusing on the development of an innovative and sustainable concrete recycling process. To that end, this article will firstly present the main achievements and ongoing activities for developing the innovative concrete recycling technology in the course of the EU C2CA, HISER and VEEP projects. In addition some figures related to the cost of each recycling unit process and the selling price of the recycled products are presented., Materials and Environment

The Master's programme Industrial Ecology is jointly organised by Leiden University and Delft University of Technology. - Two main features of the construction and demolition systems translate into environmental pressure; an increasing need for building materials, to provide and maintain the infrastructure for growing urban populations, and the management of large amounts of waste streams that come from demolition and construction activities. Because of its high volume and limited management alternatives, the concrete waste is a critical stream. In the Netherlands, 95% of concrete rubble from construction and demolition waste is recycled into an application of lower grade through regular crushing. Alternative methods for reintegrating the coarse fraction into new concrete are Advanced Dry Recovery (ADR), electrical fragmentation (EF) and wet processing. Around 2% of the concrete waste stream is wet processed, but this alternative is energy intensive and expensive. Oppositely, ADR and EF are simpler technologies that also offer to retrieve the value of concrete, but are still at a pilot stage. This research project focuses on ADR as a recycling alternative to regular crushing in specific scenarios, addressing financial and environmental implications through the use of Life Cycle Assessment (LCA) and Life Cycle Costing (LCC). The main research question is: What are the environmental and economic implications of different concrete recycling scenarios in the Netherlands? The applicability of the results is that of a first estimate of the economic and environmental implications of shifting to ADR concrete-rubble recycling, with a detailed coverage of costs and types of environmental interventions. The research question is addressed from two different perspectives. First, a case study from the HISER project, sponsored by the European Union, is evaluated integrating LCA and LCC. The case is about the demolition of an end-of-life building and the construction of a new build, Technology, Policy and Management, Engineering Systems and Services; Values, Technology and Innovation, Industrial Ecology Joint degree Leiden & Delft

Recycled concrete aggregates (RCA) can be used as a replacement of natural aggregates for a concrete production to save natural sources and also to decrease amount of demolition waste which has to be landfilled. Precast production generates some percentage of defected elements which are carted off and recycled with other demolition waste. In this study defected elements are separately recycled into RCA with beneficial properties and used directly into new mixtures for precast elements. Results from testing of RCA and application into new concrete mixtures are presented. It was proved that the replacement of raw aggregates by RCA up to 20% has no negative influence on physico-mechanical properties of concrete., Recyklované betonové kamenivo (RCA) lze použít jako náhradu přírodní kamenivo pro výrobu betonu, zachránit přírodní zdroje, ale i ke snížení množství odpadu demoličního, který je ukládán na skládku. Prefa výroba generuje určité procento vadného prvky, které jsou vyváženy a recyklovány s ostatním demoličním odpadem. V této studii jsou zmetky samostatně drceny na RCA, s dobrými vlastnosti a přímo užity do nových směsí pro prefabrikované prvky. Jsou prezentovány výsledky z testování RCA a aplikace do nové betonové směsi. Bylo prokázáno, že nahrada přírodního kameniva pomocí RCA až do 20 % nemá negativní vliv na fyzikálně mechanické vlastnosti betonu.

Recycled concrete aggregates (RCA) can be used as a replacement of natural aggregates for a concrete production to save natural sources and also to decrease amount of demolition waste which has to be landfilled. Precast production generates some percentage of defected elements which are carted off and recycled with other demolition waste. In this study defected elements are separately recycled into RCA with beneficial properties and used directly into new mixtures for precast elements. Results from testing of RCA and application into new concrete mixtures are presented. It was proved that the replacement of raw aggregates by RCA up to 20% has no negative influence on physico-mechanical properties of concrete., Recyklované betonové kamenivo (RCA) lze použít jako náhradu přírodní kamenivo pro výrobu betonu, zachránit přírodní zdroje, ale i ke snížení množství odpadu demoličního, který je ukládán na skládku. Prefa výroba generuje určité procento vadného prvky, které jsou vyváženy a recyklovány s ostatním demoličním odpadem. V této studii jsou zmetky samostatně drceny na RCA, s dobrými vlastnosti a přímo užity do nových směsí pro prefabrikované prvky. Jsou prezentovány výsledky z testování RCA a aplikace do nové betonové směsi. Bylo prokázáno, že nahrada přírodního kameniva pomocí RCA až do 20 % nemá negativní vliv na fyzikálně mechanické vlastnosti betonu.

Recycled concrete aggregates (RCA) can be used as a replacement of natural aggregates for a concrete production to save natural sources and also to decrease amount of demolition waste which has to be landfilled. Precast production generates some percentage of defected elements which are carted off and recycled with other demolition waste. In this study defected elements are separately recycled into RCA with beneficial properties and used directly into new mixtures for precast elements. Results from testing of RCA and application into new concrete mixtures are presented. It was proved that the replacement of raw aggregates by RCA up to 20% has no negative influence on physico-mechanical properties of concrete., Recyklované betonové kamenivo (RCA) lze použít jako náhradu přírodní kamenivo pro výrobu betonu, zachránit přírodní zdroje, ale i ke snížení množství odpadu demoličního, který je ukládán na skládku. Prefa výroba generuje určité procento vadného prvky, které jsou vyváženy a recyklovány s ostatním demoličním odpadem. V této studii jsou zmetky samostatně drceny na RCA, s dobrými vlastnosti a přímo užity do nových směsí pro prefabrikované prvky. Jsou prezentovány výsledky z testování RCA a aplikace do nové betonové směsi. Bylo prokázáno, že nahrada přírodního kameniva pomocí RCA až do 20 % nemá negativní vliv na fyzikálně mechanické vlastnosti betonu.

Recycled concrete aggregates (RCA) can be used as a replacement of natural aggregates for a concrete production to save natural sources and also to decrease amount of demolition waste which has to be landfilled. Precast production generates some percentage of defected elements which are carted off and recycled with other demolition waste. In this study defected elements are separately recycled into RCA with beneficial properties and used directly into new mixtures for precast elements. Results from testing of RCA and application into new concrete mixtures are presented. It was proved that the replacement of raw aggregates by RCA up to 20% has no negative influence on physico-mechanical properties of concrete., Recyklované betonové kamenivo (RCA) lze použít jako náhradu přírodní kamenivo pro výrobu betonu, zachránit přírodní zdroje, ale i ke snížení množství odpadu demoličního, který je ukládán na skládku. Prefa výroba generuje určité procento vadného prvky, které jsou vyváženy a recyklovány s ostatním demoličním odpadem. V této studii jsou zmetky samostatně drceny na RCA, s dobrými vlastnosti a přímo užity do nových směsí pro prefabrikované prvky. Jsou prezentovány výsledky z testování RCA a aplikace do nové betonové směsi. Bylo prokázáno, že nahrada přírodního kameniva pomocí RCA až do 20 % nemá negativní vliv na fyzikálně mechanické vlastnosti betonu.

In the C2CA concrete recycling process, autogenous milling of the crushed End of Life (EOL) concrete is a mechanical method to remove cement paste from the surface of aggregates. During autogenous milling, the combination of shearing and compression forces, promotes selective attrition and delivers a better liberation. In order to investigate the effects of shear and compression on the cement recovery and specify the importance of them, a new set-up is designed and constructed. This set-up permits aforesaid forces to be determined and controlled. For experimental design, the MINITAB 16 software was used and 13 different experimental runs based on varying shear and compression forces were conducted. After each experiment, the amount of cement recovery using XRF analysis, water absorption of the recycled aggregates and energy consumption during the process were measured. Results show that both shear and compression forces have in?uence on improving the cement recovery. With simple changes in the setting of an autogenous mill like bed height or residence time the need for high-cost secondary crushing during concrete recycling could be eliminated., Structural Engineering, Civil Engineering and Geosciences

In the C2CA concrete recycling process, autogenous milling of the crushed End of Life (EOL) concrete is a mechanical method to remove cement paste from the surface of aggregates. During autogenous milling, the combination of shearing and compression forces, promotes selective attrition and delivers a better liberation. In order to investigate the effects of shear and compression on the cement recovery and specify the importance of them, a new set-up is designed and constructed. This set-up permits aforesaid forces to be determined and controlled. For experimental design, the MINITAB 16 software was used and 13 different experimental runs based on varying shear and compression forces were conducted. After each experiment, the amount of cement recovery using XRF analysis, water absorption of the recycled aggregates and energy consumption during the process were measured. Results show that both shear and compression forces have in?uence on improving the cement recovery. With simple changes in the setting of an autogenous mill like bed height or residence time the need for high-cost secondary crushing during concrete recycling could be eliminated., Structural Engineering, Civil Engineering and Geosciences

The emerging sustainable development movement in the construction industry requires the recycling of waste materials to reduce the negative environmental impact of construction activities. In many countries, old concrete, a major waste stream generated from the demolition of obsolete buildings/structures, is being recycled. However, for various reasons, progress toward concrete recycling varies from country to country. This paper discusses the current status of concrete recycling in the U.S. construction industry based on results from a two-part questionnaire survey. The first part of the survey collects information on the recycling practices of surveyed concrete companies. The second part adapts questions from a study conducted in Australia and Japan to examine the awareness, benefits, difficulties, and recommended methods related to concrete recycling. The findings showed that although recycling old concrete is common in the U.S., its application is mostly limited to backfill and pavement base; using waste concrete in new concrete production is not widely applied. There are also similarities and differences in the perceptions of concrete recycling between U.S. concrete companies and their counterparts in Australia and Japan.

The emerging sustainable development movement in the construction industry requires the recycling of waste materials to reduce the negative environmental impact of construction activities. In many countries, old concrete, a major waste stream generated from the demolition of obsolete buildings/structures, is being recycled. However, for various reasons, progress toward concrete recycling varies from country to country. This paper discusses the current status of concrete recycling in the U.S. construction industry based on results from a two-part questionnaire survey. The first part of the survey collects information on the recycling practices of surveyed concrete companies. The second part adapts questions from a study conducted in Australia and Japan to examine the awareness, benefits, difficulties, and recommended methods related to concrete recycling. The findings showed that although recycling old concrete is common in the U.S., its application is mostly limited to backfill and pavement base; using waste concrete in new concrete production is not widely applied. There are also similarities and differences in the perceptions of concrete recycling between U.S. concrete companies and their counterparts in Australia and Japan.

The emerging sustainable development movement in the construction industry requires the recycling of waste materials to reduce the negative environmental impact of construction activities. In many countries, old concrete, a major waste stream generated from the demolition of obsolete buildings/structures, is being recycled. However, for various reasons, progress toward concrete recycling varies from country to country. This paper discusses the current status of concrete recycling in the U.S. construction industry based on results from a two-part questionnaire survey. The first part of the survey collects information on the recycling practices of surveyed concrete companies. The second part adapts questions from a study conducted in Australia and Japan to examine the awareness, benefits, difficulties, and recommended methods related to concrete recycling. The findings showed that although recycling old concrete is common in the U.S., its application is mostly limited to backfill and pavement base; using waste concrete in new concrete production is not widely applied. There are also similarities and differences in the perceptions of concrete recycling between U.S. concrete companies and their counterparts in Australia and Japan.