Resource efficiency and circular economy (CE) has become increasingly relevant to the Swedish construction company NCC in connection to the plans of demolishing the current head office in Stockholm and building a new head office next to it. NCC wants to investigate how to minimize the negative sustainability implications of bringing down a commercial facility well before its life length has expired, through exploring the possibilities of integrating principles of CE in future planning‐and construction processes. This study seeks to understand how the Swedish construction company NCC could work with decision-making for CE in order to keep their materials in the loop. As the concept of CE is broad there are many options for working with its principles. However, the construction industry is relatively new to these and a list of priorities would therefore be helpful in such an initial phase, as focusing on all would be inefficient and rather daunting. Thus, this study suggests a multi-criteria decision analysis (MCDA) as a tool for decision-making and prioritizing between various approaches to CE. Together with NCC, an MCDA was performed where three different options for working with CE were analysed (Waste as Resource, Circular Design and Circular Business Models). In a focus group, 17 criteria that were relevant to NCC were developed as a basis for analysing the options. These were then defined, scored and weighted to reveal a most preferable option. The MCDA showed that the most preferable approach to CE for NCC is working with circular design, i.e. Design for Deconstruction (DfD), followed closely by measures to increase the rate of reuse and recycling of already existing construction- and demolition waste. However, the sensitivity analysis revealed that if economic criteria received a higher weight, increased reuse and recycling is the most preferable option. MCDA was deemed a helpful decision-making tool for CE principles. While the scoring and weighting is subjective and it is challenging to quantify the criteria, the strength lies in bringing a new and innovative topic on the agenda by gathering key decision-makers in focus groups to discuss and learn. A preliminary study to this thesis was conducted at NCC (Tabrizi, 2015) with the aim of conducting a survey of good examples with regard to development of commercial properties that are designed for flexibility and deconstruction during refurbishment and end‐of‐life. It showed that the challenges relate to the hesitant perception of secondary material, design and construction limitations, the need for material documentation, organization and logistics as well as creating sustainable business models. Key success factors for overcoming these challenges for NCC is working towards better communication and promotion of secondary material through information sharing, building up a knowledge base and internal targets, as well as establishing a consistent work methodology for DfD in order to move NCC towards a circular economy.

Efficient management of construction and demolition components is crucial for the sustainability of the environment, society, and economy. Reusing construction materials is an effective way to reduce construction debris. However, reuse is hurdled due to different factors, and one of the leading causes of these factors is improper information flow. The information flow is the transfer of relevant information within the network about construction materials such as quality, quantity and other specifications in the reuse aspect. The seamless flow of relevant information on the construction process and materials is crucial to facilitate reuse. Unfortunately, there are considerable obstacles to achieving a seamless information flow. By identifying and addressing the barriers that hinder the current information flow, we can thrive towards a seamless flow of information that facilitates reuse within the construction industry. This paper examines the challenges in the flow of information within the Swedish construction industry using a qualitative exploratory research design. The research also explores some strategies adopted by a few stakeholders to promote reuse. The study is performed using existing literature and interviews with various stakeholders mainly in the Swedish construction industry. The research identifies several barriers in information flow, including a lack of collaboration among stakeholders, fragmented information, no standardization, business models that do not support reuse, and low awareness of reuse prospects. To gain better insight into the flow of information, a five-component framework has been devised based on these challenges.

In 2008, the State of Florida established a recycling goal of 75% to be achieved by 2020. In response to the Florida goal Orange County (OC), Florida has made the development and implementation of an efficient strategy for landfill diversion of its solid waste a top priority. The Florida Department of Environmental Protection (FDEP) estimated that 23 % of municipal solid waste was generated by construction and demolition (C&D) activities in 2009, with only 30 percent of C&D debris being recycled. Therefore, OC decided to create a solid waste integrated resource plan (SWIRP) initially focused on the recovery and recycling of C&D materials (2010). For SWIRP development, OC decision makers need the best available data regarding C&D debris generation and composition and an understanding of the potential markets available for recycled materials. In this investigation debris generation was estimated over the period of 2001 to 2009 for the largest single governing body within OC, unincorporated OC (UOC), representing 65 percent of county population. The debris generation model was constructed for years 2001-2010 using area values for C&D activities in six sectors obtained from building permits and debris generation multipliers obtained from literature values. The benefit of the model is that as building permit information is received, debris generation estimations can also be expediently updated. Material composition fractions obtained from waste characterization studies of landfills in the Central Florida area were applied to the debris generation model resulting in a material iv composition for all sectors for years 2001-2010. The material composition of the debris stream was found to be, on average, concrete (53%) drywall (20%), wood (12%), a miscellaneous fraction (8%), asphalt roofing material (4%), metal (2%), cardboard (1%) and carpet and padding (1%). A market analysis was performed for concrete, drywall, wood, asphalt roofing shingles and residual screened materials (RSM). It was found that statewide, markets existed for 100 percent of the materials studied and could replace significant amounts of natural material feedstocks, but that the development of more local markets was vital to meeting OC’s diversion goal to minimize the cost of transporting recyclables.

Yes / In this study, the main emphasis is placed on the development and characterization of alkali-activated binders completely produced by the use of mixed construction and demolition waste (CDW)-based masonry units as aluminosilicate precursors. Combined usage of precursors was aimed to better simulate the real-life cases since in the incident of construction and demolition, these wastes are anticipated to be generated collectively. As different masonry units, red clay brick (RCB), hollow brick (HB) and roof tile (RT) were used in binary combinations by 75-25%, 50-50% and 25-75% of the total weight of the binder. Mixtures were produced with different curing temperature/periods and molarities of NaOH solution as the alkaline activator. Characterization was made by the compressive strength measurements supported by microstructural investigations which included the analyses of X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX). Results clearly showed that completely CDW-based masonry units can be effectively used collectively in producing alkali-activated binders having up to 80 MPa compressive strength provided that the mixture design parameters are optimized. Among different precursors utilized, HB seems to contribute more to the compressive strength. Irrespective of their composition, main reaction products of alkali-activated binders from CDW-based masonry units are sodium aluminosilicate hydrate (N-A-S-H) gels containing different zeolitic polytypes with structure ranging from amorphous to polycrystalline.

Yes / As a viable option to upcycle construction and demolition waste (CDW) into value-added materials, geopolymer technology is emerging. Most studies investigate CDWs in a separated form or in combination with mainstream pozzolanic/cementitious materials focusing only on fundamental properties of geopolymer pastes, not considering to scale such materials to the level of their application in the forms of structural mortars/concretes or to characterize long-term performance/durability. This study investigated the development and characterization of ambient-cured mortars with mixed CDW-based geopolymer binders and untreated fine recycled concrete aggregates (FRCA). Mixture of CDW-based roof tile (RT), red clay brick (RCB), hollow brick (HB), concrete (C), and glass (G) was used as the precursor, while ground granulated blast furnace slag (S) was used in some mixtures to partly replace CDW precursors. Compressive strength, durability-related parameters including drying shrinkage, water absorption, and efflorescence, microstructure and materials sustainability were evaluated. Results showed that 28 d compressive strength results above 30 and 50 MPa is achievable with the entirely CDW-based and slag-substituted mortars, which were found improvable to have entirely CDW-based structural concretes. Drying shrinkage of the mortars is slightly higher than that of conventional cementitious/geopolymeric systems although it can be minimized significantly through mixture optimization. Water absorption values remain comparable with the literature. CDW-based geopolymer mortars outperform Portland cement mortars in terms of CO2 emission and energy requirement. Our findings show that via utilizing CDW-based constituents in mixed form as precursor and waste aggregates, it is possible to develop greener construction materials with acceptable strength and long-term performance. / This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100. The authors also wish to acknowledge the support of the Scientific and Technical Research Council (TUBITAK) of Turkey provided under project: 117M447.

Yes / Construction and demolition waste (CDW) management and recycling practices are crucial for transitioning to a circular economy. This study focuses on the detailed characterization of CDWs, including hollow brick (HB), red clay brick (RCB), roof tile (RT), concrete (C), and glass (G), collected from seven different sites. The CDWs were characterized based on particle size distribution, chemical composition, and crystalline nature. Pozzolanic activity was evaluated through compressive strength measurements of cement mortars with 20% cement replacement by CDWs at 7, 28, and 90 days. The results showed that clayey CDWs exhibited similar physical/chemical properties and crystalline structures. Compositions of Cs varied significantly based on their original materials. CDWs satisfied the minimum strength activity index for supplementary cementitious materials, with pozzolanic activity influenced by fineness and SiO2+Al2O3 contents. The average strength activity indexes for HB, RCB, RT, C, and G were 84.5%, 86.3%, 83.4%, 80.7%, and 75.8%, respectively. Clayey CDWs contributed to mechanical strength development, while Cs' contribution was related to hydration of unreacted cementitious particles. G exhibited the weakest pozzolanic activity due to its coarser particle size. Overall, CDWs demonstrated suitable properties for use as supplementary cementitious materials in PC-based systems.

This essay will address if and how it is possible to reuse and recycle wood waste and CDWW (construction and demolition wood waste). The background will have a short introduction and then be divided into 3 sections. The first section addresses similarities and differences between linear vs. circular economy. The second section will take up bioeconomy and how it is managed in the different countries in the world, and the last part takes up wood waste management. The purpose of this thesis is to investigate from literature if it is possible to reuse and recycle wood waste and CDWW. By reviewing case studies, see if it is possible to implement a practical sustainable recycling worldwide. There are four questions that will be answered to see if it is possible. Those are: 1, Are there enough volumes of wood waste for it to be worth to reusing/recycling it? 2, What opportunities does it provide and how can it affect society, economy, and the environment? 3, Is it worth investing in facilities that only accept wood waste and reuse/recycle the material? 4, How have the trends with wood waste been according to the data collected? The methods that have been used are literature study, qualitative and quantitative methods. Qualitative as an interview has been conducted, and quantitative as data for wood waste in Borås has been compiled. The result showed that there exist enough volumes for it to be worth reusing and recycling, however, the volumes has gone down significantly and are not stable, though this could be argued due to the COVID-19 pandemic and will most likely change and go up in volume within the next few years. There have not been any studies on how the society could be affected by reusing and recycle wood waste, although from an economic and environmental perspective it shows a positive outcome, such as new jobs get created and less deforestation and less reduction of biological diversity. Depending on the type of wood waste the facility receives, it can affect whether it is profitable or not, as the more hazardous chemicals exist in the wood residues, the more difficult and expensive the treatments and recycling becomes.

Yes / CDW-based concrete requires alkali-activators to generate geopolymerization process. These alkali-activators are difficult to be handled at the construction site and one of the rational ways to built reinforced geopolymer structures is the prefabricated construction. The connection of the precast structures is the most vulnerable component under the effect of seismic actions. Proper detailing and design of connections are crucial for sufficiently-ductile performance under seismic loading. Additionally, to achieve the disassembling and reusing of structural members, a demountable connection, i.e., dry connection, should be used instead of a wet connection. In this study, four novel fully-demountable connections for reinforced construction and demolition waste-based (CDW) geopolymer concrete members are developed. Seismic performances of these different demountable connections and one reference monolithic connections are experimentally investigated. The connections are subjected to reversed cyclic lateral displacements under constant axial loading. Comparisons are made referring to observed damage patterns, connection strengths, moment–curvature relations, initial stiffnesses, plastic hinge lengths, and energy dissipation characteristics of the proposed demountable connections and the monolithic connection. The results of the experimental study indicate that one proposed demountable connection exhibited larger lateral capacity and better seismic performance than its monolithic counterpart, whereas the other three proposals showed less performance than the monolithic counterpart. / The authors gratefully acknowledge the financial assistance of the European Union’s Horizon 2020 research and innovation programme under grant agreement No: 869336, ICEBERG

Yes / Developing a fast, cost-effective, eco-friendly solution to recycle large amounts of construction and demolition waste (CDW) generated from construction industry-related activities and natural disasters is crucial. The present investigation aims to offer a solution for repurposing CDW into building materials suitable for accelerated construction and housing in developing countries and disaster-prone areas. Feasibility of recycled concrete aggregate (RCA) inclusion in geopolymer mortars constituted entirely from CDW (masonry elements) was investigated via an environmental impact-oriented approach by addressing the composition related key parameters. Mechanical performance was evaluated through compressive strength tests, and scanning electron microscope (SEM) imaging with line mapping analyses were carried out to monitor the interfacial transition zone (ITZ) properties. To investigate the environmental impacts of the geopolymer mortars and highlight the advantages over Portland cement-based mortars, a cradle-to-gate life cycle assessment (LCA) was performed. Findings revealed that roof tile (RT)-based geopolymer mortars mainly exhibited better strength performance due to their finer particle size. Mixtures activated with 15 M NaOH solution and cured at 105 °C achieved an average compressive strength above 55 MPa. RCA size was the most influential parameter on compressive strength, and a smaller maximum RCA size significantly increased the compressive strength. Microstructural analyses showed that the ITZ around smaller RCAs was relatively thinner, resulting in better compressive strength results. LCA proved that CDW-based geopolymer mortars provide the same compressive strength with around 60% less CO2 emissions and similar energy consumption compared to Portland cement-based mortars. / This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 894100. The authors also wish to acknowledge the support of the Scientific and Technical Research Council of Turkey (TUBITAK) provided under project: 117M447

Yes / Geopolymer concrete is a promising candidate to replace conventional concrete as geopolymer concrete depends on alkali-activated binders instead of Portland cement. The elimination of cement from the mixture results in the reduction of the greenhouse gas release. From the literature, it is known that the micro-scale characteristics of the geopolymer concrete are similar to its counterparts. However, the structural performance of geopolymer elements should be investigated in detail. Therefore, in this study, the structural performance of reinforced geopolymer concrete beams is compared by conducting bending tests to determine the shear behavior of new generation geopolymer concrete produced from entirely construction and demolition wastes (CDW). In these tests, geopolymer concrete with recycled aggregates, geopolymer concrete with natural aggregates, conventional concrete with recycled aggregates, and conventional concrete with natural aggregates are used in order to study the possibility of reaching fully-recycled construction materials. Three different shear-span-to-depth ratios (a/d) are utilized to investigate the different modes of failure. Therefore, the structural performance of beams was, firstly, compared for mixtures without recycled aggregates to control the possible side effects of 100% recycled concrete construction. Load-deflection curves, moment-curvature curves, and crack patterns were utilized to conclude the performance of geopolymer concrete. Test results revealed that geopolymer concrete beams exhibited similar performance to the conventional concrete beams of the same grade. However, the inclusion of recycled aggregates caused a shift in the failure mechanism from shear-dominated to flexure-dominated, especially in specimens with larger a/d ratios. Finally, the capacity prediction performance of current codes, i.e., TS500 and ACI318, are also examined, and the calculations resulted that the current code equations have a percentage error of approximately 55% on average, although TS500 equations performed slightly better. / The authors gratefully acknowledge the financial assistance of the Scientific and Technical Research Council (TUBITAK) of Turkey and the British Council provided under projects: 218M102 and European Union’s Horizon 2020 research and innovation programme under grant agreement No: 869336, ICEBERG (Innovative Circular Economy Based solutions demonstrating the Efficient recovery of valuable material Resources from the Generation of representative End-of-Life building material).