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Timber-Cardboard Sandwich (TCS) panels are an emerging class of lightweight and low cost structural composite material, made from bio-based and recycled waste materials. However, there is a lack of data and knowledge as to their compressive behaviours, preventing their structural application as column or wall panel elements. This paper conducts experimental and analytical investigations to address this knowledge gap by characterising the eccentric axial performance of TCS columns. Thirty columns were tested under uniaxial compressive loading, with specimen types developed to investigate the influence of four key design parameters: cardboard core source material, the type and thickness of timber facings, and column slenderness ratio. Test results indicate that the face crushing governing failure mechanism and column ultimate capacity were primarily controlled by the timber facing material, with no observable influence of failure contributions from the cardboard core. Based on experimental observations, analytical models were developed to predict load-carrying capacity and lateral deflection for eccentrically-loaded TCS columns, giving ultimate load predictions within 5% for all studied column types. Research findings provide valuable insights that will enable cardboard to be more widely used in sustainable composite building products. [Display omitted] • Structural performance of timber-cardboard sandwich composite columns is investigated. • Columns achieve high load-bearing capacity with performance governed by timber facings. • Analytical models accurately predict eccentric load capacity and lateral deflection. • Cardboard core material type has minimal influence on structural performance but impacts production cost. [ABSTRACT FROM AUTHOR]

The construction industry faces the rising challenge of circularity, and digital transformation emerges as a pivotal solution. However, limited stakeholder involvement impedes the adoption of digital transformation. The existing literature does not analyze stakeholders' perceptions of digitalization adoption barriers. Therefore, this study investigates the barriers hindering digital transformation in circular construction by examining the varied perceptions of key stakeholders. The study contributes to aligning stakeholders' interests and leads to targeted and effective interventions, enhancing the likelihood of successful adoption. Using the Stakeholder Theory, the study identified contractors, investors, clients, waste managers and government as the most influential stakeholders in circular construction. This study explores skill and knowledge barriers, market barriers, regulatory barriers, organizational and cultural barriers, and financial and resource barriers as key dimensions hindering digital circular practices. The study integrates the fuzzy Delphi method, fuzzy decision-making trial and evaluation laboratory, and analytical network processing to address uncertainties and interrelationships among barriers. The findings indicate that stakeholders hold differing perceptions regarding the most critical barriers; however, there is a consensus that critical aspects are skill and knowledge, organizational and cultural, and regulatory barriers. Practical barriers include lack of government support, resistance to change, lack of feasibility information, lack of training capabilities, and poor digital literacy. The study provides theoretical and practical implications, informing future research and interventions to develop targeted strategies and initiatives. [ABSTRACT FROM AUTHOR]

Exorbitant greenhouse gas emissions associated with commercial sodium silicates (SS) have curtailed the large-scale practical implementation of geopolymers and have also led to discrepancies related to their sustainability. As a result, the extraction of SS from silica-rich biomass/agricultural waste ashes (AGWA) have gained the attention of researchers. This process involves heat treatment of AGWA with sodium hydroxide in addition to the calcination to produce the ash itself, thus requiring a systematic study to justify its sustainability. Therefore, this study presents an integrated techno-economic analysis (TEA) and life cycle assessment (LCA) to determine the economic and environmental feasibility of AGWA-derived activators for geopolymer concrete synthesis. The LCA results showed a 60–62% reduction in the greenhouse gas emissions of commercial SS-based geopolymer. A significant improvement was also observed in photochemical ozone formation, wherein the emissions were lesser from binders using AGWA based SS as compared to binders produced with commercially available SS. The TEA indicated that although the AGWA-derived SS reduced the cost of the activator by 50–70%, the overall cost of geopolymer concrete with these activators was still higher than OPC based concrete. The hydrothermal process was found to have a lower CO 2 emissions and production cost as compared to the thermochemical method to prepare AGWA-derived SS. All in all, the innovative valorization of biomass-waste-derived sodium silicate in geopolymer concrete has a lot of potential to foster a circular bioeconomy by closing the loop of agricultural waste and also promote circular construction by repurposing of waste materials in concrete. [Display omitted] • Biomass waste derived sodium silicate can be used as an activator for geopolymer. • 60–62% lesser GHG emissions than commercial SS based geopolymer. • Cost of commercial activator reduced by 40–70%. • Hydrothermal method had lesser production cost than thermochemical method. • Biomass waste derived activators foster circular economy. [ABSTRACT FROM AUTHOR]

Monitoring the transition to a circular economy requires not only the measurement of circularity but also of environmental impacts, which often present trade-offs due to different perspectives when assessing a product. This article proposes a novel approach, named ECI-MCDA, to combine circularity and Life-Cycle Assessment (LCA) indicators via Multi-Criteria Decision Analysis (MCDA) non-compensatory methods (Electre I and Electre TRI). The proposed approach includes a clustering analysis to inform the choice of circularity indicators, and a robustness analysis to assess the influence of the MCDA parameters. The ECI-MCDA approach is applied to a multifunctional building sandwich-block (CleanTechBlock) composed of a thermal insulation layer incorporating over 90% recycled glass. The environmental performance and circularity of CleanTechBlock is assessed for different end-of-life (EoL) scenarios, including reuse, closed- and open-loop recycling. The ECI-MCDA approach has demonstrated its efficacy in handling divergent results between circularity and environmental performance, identifying an alternative that addresses both perspectives. Additionally, the proposed approach shows the potential to support decision-making to improve circularity and environmental performance, thereby promoting the eco-design of products. • An application-driven approach to evaluate circular economy strategies. • Selection of circularity indicators at product-level using clustering methods. • Non-compensatory MCDA methods to select the most preferred alternative. • Criteria weighing by experts complemented with stochastic robustness analysis. • Trade-offs identified between LCA and circular economy perspectives. [ABSTRACT FROM AUTHOR]

The building and construction industry is characterized by high consumption of raw materials, waste generation, and significant energy-related greenhouse gas emissions. A substantial change in the way this sector operates is necessary to reduce its strong negative impact on the environment. In this context, the implementation of circular strategies is critical to achieving sustainable development. Reusing construction products derived from obsolete buildings at their end of life is increasingly being investigated as a strategy to achieve circularity. Despite growing interest, both in the literature and in the industry, several challenges hinder the large-scale adoption of circular reuse. The purpose of this study is to contribute to the efficient implementation of reuse in practice. The focus is on data and information that can support the reusability assessment of construction products. The findings are obtained through a case study comprising a building project in Bergen, Norway. First, the study assesses which material properties and information are available in the project, leading to the definition of eight information-driven evaluation criteria and a three-step process for reuse. The three-step process encompasses the following: (1) collecting information, (2) information-driven evaluations, and (3) planning for reuse. Each criterion is then shown in a reusability matrix, emphasizing an information-driven approach to reuse that has the potential to be extended beyond the context of the case study. Considerations for improving data management in a circular reuse process are discussed. This study provides an innovative method that may lead to a circular economy and sustainable development in the future. • The reuse of reclaimed building elements from an obsolete building at its end of life was deemed critical for circular construction. • A three-step process for the reuse of building elements in a case study project was defined. • The information-driven evaluations to define which products could be reused in the case study were presented with their respective criteria. [ABSTRACT FROM AUTHOR]

Building component reuse (BCR) is a critical means to reach sustainability goals in the construction industry through decreasing resource consumption, waste generation, and associated emissions. However, little is known about how BCR in circular construction can create economic value and opportunities for value creation and capture. Therefore, a qualitative multiple case study was conducted of two construction projects in Finland in which precast concrete building components were reused. Extensive datasets, combining interview data, observation, and written materials, were gathered to investigate and compare the projects, examine how economic value can be created from reuse for construction value chain actors, and identify the factors that determine value capture potential. The findings show that BCR may create economic value by decreasing costs and material consumption, but also by increasing material performance and creating new circular business models and revenue sources (such as concrete refurbishment and reuse-oriented design). Twenty-one value capture determinants for BCR were identified and classified into five value clusters on the micro, meso, and macro levels. The study expands circular construction research by associating circular value potential with the feasibility aspects of reuse in construction, giving businesses invaluable insights on how to gain economic benefits from concrete BCR. • Two building projects reusing concrete components are studied. • Economic value can be captured from component reuse throughout the process. • Twenty-one value capture determinants for concrete component reuse are identified. • Reuse can generate functional value, cost minimisation, and new revenue sources. [ABSTRACT FROM AUTHOR]

Lack of knowledge and tools hampers circular transition in the construction industry. This study analyzes the potential of a framework of circular indicators put forward by the Building Research Establishment Environmental Assessment Method (BREEAM-C) as an answer to the prevailing need of a metric for building circularity assessment to promote circular construction. A qualitative analysis approach is adopted, involving literature review, comparative case study and semi-structured interviews conducted for collecting expert opinions. An in-depth scrutiny of the BREEAM-C indicators revealed that they are rooted in circular principles, cover building circularity realizable through circular strategies, and have given due consideration to circularity in different impact areas, structural layers and life-cycle stages of buildings. Moreover, BREEAM-C indicators not only show capacity in identifying CE-related practices implemented, but also serve as benchmarks testifying that CE principles/strategies are incorporated in the design, construction, operation and management of the buildings. Despite having room for expansion, BREEAM-C has proven to be applicable and practical with potential for use in Taiwan as confirmed by expert opinions. Nevertheless, adaptation/localization is required to cater for different concerns with respect to climate and safety as well as local context and legislations. [Display omitted] • New circular indicators examined using qualitative analysis approach. • These indicators cover circular economy strategies and building life cycle stages. • These indicators constitute a candidate building circularity assessment metric. • Their validity and applicability proved through comparative case studies. • Their potential to support building circularity assessment confirmed by experts. [ABSTRACT FROM AUTHOR]

The increasing demand for and consumption of wood requires special attention in order to keep the wood industry sustainable. Therefore, timber reuse is presented as a solution to control the demand side. Unfortunately, the perception of timber decay poses a major barrier for reuse practices. Therefore, this article presents a factorised service life prediction model for wooden components that aims to promote their reuse. The model is based on the Australian service life prediction model, Timberlife, and the European CLICK design model's dose-response model. It predicts the potential for reuse of timber components based on their expected and remaining service life. To determine the service life, the model includes factors that differentiate between wood species, soil characteristics, regional climate and how the investigated components are connected to other components. The presented model focuses on in-ground and above-ground fungal decay and is limited to northwestern Europe. Opportunities for further research include, e.g., a further investigation of the soil characteristics' influence on decay, and evaluating the lag time for regions outside northwestern Europe. The presented service life prediction model can increase awareness and support a circular construction industry. • a service life prediction model for wooden components to promote their reuse. • Mapping in-ground and above-ground fungal decay to assess the wood's reuse potential. • Increasing awareness on timber reusability supports a circular construction industry. [ABSTRACT FROM AUTHOR]

• Review of digital tools to support the circular economy in the built environment. • Identification and comparison of CAD, BIM, and computational design plugins. • Highlights possibilities and limitations of the various approaches and tools. • Beyond LCA, including circularity indicators and computational methods for a CE. • Recommendations for further development of digital tools. This paper reviews digital tools for supporting the Circular Economy (CE) in the built environment. The study provides a bibliometric analysis and focuses on computer-aided design (CAD), building information modeling (BIM), and computational plugins that can be used by practitioners. While Life Cycle Assessment (LCA) is the primary methodology for evaluating buildings' environmental performance, the study identifies tools beyond LCA, including computational methods and circularity indicators, that can support the evaluation of circular design strategies. Our review highlights limitations in tools' functionalities, including a lack of representative data for LCA and underdeveloped circularity indicators. The paper calls for further development of these tools in terms of interoperability aspects, integration of more sources of data for LCA and circularity, and possibilities for a comprehensive evaluation of design choices. Computational plugins offer greater flexibility, while BIM-LCA integrations have the potential to replace dedicated LCA software and spreadsheets. Additionally, the study identifies opportunities for novel digital methods, such as algorithms for circular design with various types of reused building elements, and sharing of digital twins and material passports. This research can inform future studies and support architects and engineers in their efforts to create a sustainable built environment. [ABSTRACT FROM AUTHOR]

• Produced water can successfully be used as concrete mixing water. • Produced water increases pore formation factor in low w/c systems. • Produced water reduces workability by 20% • Produced reduces setting time by 25% • Concrete with 20% produced water maintain moderate corrosion resistance. The application of alternative non-potable water sources can be leveraged to build infrastructure components that support sustainable industrial operations in regions that experience high frequency of freshwater shortages. This study examines how the use of highly saline produced water (as mixing water) in portland cement mortar impacts workability, setting time, electrical resistivity, pore formation, and microstructure. The results show that produced water decreases both mortars setting time by 30% and workability by 20%. Alkali solubility and pore solution conductivity are also influenced by the produced water-increasing pore solution conductivity by approximately 100 mS/cm. The produced water reacts with the cementitious material to form small deposits of Friedel's salts and calcite that primarily fill the smaller pores in the matrix-thus primarily influencing the pore structure of low w/c mortar systems. In the low water/cement (w/c) produced water mortar systems (0.4), both the pore formation factor (∼2X) and resistivity (∼1.5X) are significantly higher than the control (tap water mortar systems), but in the high w/c systems (0.6) both are slightly lower. The produced water mortar systems also tend to retain more moisture during dry cycling which leads to significantly lower resistivity than the control in air-dried conditions. Diluting the produced water with tap water will reduce moisture retention during dry cycling and increase resistivity. [ABSTRACT FROM AUTHOR]

• Analyses how interventions can stimulate the transition to circular construction. • Several practices of inter-organizational collaboration hinder the transition. • Project actors are central in transforming critical points of intersection. • Reflective interventions can assist project actors in changing their practices. • Interventions organized close to day-to-day practices are crucial. This paper addresses the lack of attention for the behaviours and agency of actors in organizations in the sustainability transitions literature by focussing on practices of inter-organizational collaboration in the transition to circular construction. Practices of inter-organizational collaboration can slow down this transition and are deeply embedded in the construction regime, creating critical points of intersection. This research therefore investigated how reflective interventions can enable project actors to change their practices and support the transformation of critical points of intersection into points of opportunity in circular construction. To answer this question, we adopted a case study approach with action research elements. The results of this study contribute to the sustainability transitions literature by showing how reflective interventions can assist in the transformation of critical points of intersection through five processes, including prioritising reflection on practices, critically evaluating practices, creating a breeding ground for new practices, implementing new practices and embedding new practices in partner organizations. Furthermore, we move away from the focus on policy interventions and offer more room for the agency of actors in projects, by showing how reflective interventions can create experimental environments close to the day-to-day activities of project actors enabling them to simultaneously unlearn obsolete practices and learn new practices. [ABSTRACT FROM AUTHOR]

The Circular Economy (CE) has become increasingly important across various industries. It challenges the traditional take-make-dispose approach and aims to maximize economic value while reducing waste. However, the construction industry is still in the early stages of adopting this concept, and a clear and unified definition is needed for Circular Construction (CC) in the built environment. Without a comprehensive understanding, the CE principles and practices may be misapplied, leading to inefficiencies. To address this, a Systematic Literature Review of 316 publications was conducted to bridge knowledge gaps and to propose a definition for CC. The study identified five clusters of conceptual affinities and nine attributes that contributed to the CC definition. The results suggest that the CC concept is mainly related to the conceptual affinities of Construction and Demolition Waste Management (CDWM) and the "R" strategies, that the environment is prioritized over economic and social aspects, and that CC research focuses on building over other infrastructures, especially on aspects of building disassembly and reversibility. Still, despite these advances, most research lacks a holistic view of the application of the concept. Practitioners looking to promote cleaner construction practices can benefit from this study's valuable insights, helping to guide decision-making and prevent the misuse of the circular economy concept in the built environment. • A total of 316 articles were reviewed running from 2013 to 2022. • Five research areas were analyzed from the literature review. • CDW management was mainly associated with circular construction. • The concept is mainly addressed by buildings rather than other infrastructure. • Circular Construction definition is proposed based on nine main attributes. [ABSTRACT FROM AUTHOR]

Blockchain and smart contracts are measures to speed up the diffusion of circular economy into construction processes. Nevertheless, integrated solutions that cover all the aspects of circular supply chain including network structure, business processes, and the products are still missing. This paper is an attempt to bridge this gap, through offering a workable solution to address the disconnected nature of blockchain adoption across construction procedures. Informed by the overall approach of design science research (DSR), the solution is created following the five-staged procedure of DSR: (1) problem identification, (2) treatment suggestion, (3) treatment design, (4) evaluation and (5) conclusion. Findings establish that the proposed solution is novel in several ways; it: (1) enables construction practitioners to share their building components information on a safe and immutable medium; (2) enables government authorities (i.e., city council) to track the treatment and delivery of hazardous products/materials; (3) supports the upstream circular economy design through fostering collaboration among 'designers to designers' and 'designers to asset owners' in a blockchain network; and (4) supports developing 'a bank of reusable BIM families', encouraging designers to use these items in their designs. Apart from these contributions, this study provides some fertile ground for future research. Chief among all: future studies can provide fully automated systems through integrating the solution presented here with the Internet of Things (IoT); and researchers that validate the workability of the proposed solution across various contexts and real-life projects in exposure to various settings and peculiarities. [Display omitted] • A workable solution to facilitate the adoption of circular economy by blockchain • It shares buildings components data, tracks hazardous products/materials, and supports design for circular economy. • The blockchain network as a bank of re-usable BIM families for designers. [ABSTRACT FROM AUTHOR]

To enable an industry-level transition towards the circular economy, complementary companies and other actors from the focal industry sector, resembling an industrial ecosystem, can jointly increase circulation via reuse or recycling in the system. Although all involved actors must benefit from doing so if their engagement is to be secured, little is known about how industrial ecosystem renewal towards circularity creates benefits. Therefore, this study aims to contribute by applying ecosystem and circular industry development approaches to examine how industrial ecosystems change towards circularity, particularly in regard to the little-studied reuse principle, and identify the diverse benefits of an industry's shift towards circularity via reuse. Thus, this study examines changing industrial ecosystems in the construction industry which have high environmental impacts and focuses on the needed changes to the roles, interactions, and perceptions of ecosystem actors and the diverse benefits gained by increased reuse at company, industry, and societal levels. We conducted an extensive multiple-case study of two industrial ecosystems, namely pilot projects addressing concrete-element reuse, in Finland and Sweden and gathered extensive data covering over 20 interviews, over 18 months of ethnography, and over 300 documents. Our findings show that industrial ecosystems' renewal towards circularity requires changes in the ecosystem actors' roles (role expansions and emergence of new roles), interactions (communication, collaboration mindset, utilization of tools), and perceptions (understanding the value of circulated resources, design thinking, and change resistance to conformity). We found that such changes towards circularity generate benefits at the micro level to companies (direct business, competence, and work satisfaction benefits), at the meso level to the industry (environmental, competition, and industry feasibility benefits) and at the macro level to society (environment and employment benefits). Pragmatically, we provide insights and tools for development, business, and sustainability managers, industry associations, and policymakers seeking an increase in circular practices and principles among the industry sectors, involved companies, and surrounding society. Our study contributes to industry-level and sectoral circular economy transformation, reuse, circular construction, and ecosystem research. • We conducted a qualitative case study of two concrete-element reuse pilot projects. • Renewal towards circularity requires changes in the construction industry ecosystem. • Industrial renewal changes the roles, interactions, and perceptions of ecosystem actors. • Changes within the industrial ecosystem benefit companies, industry, and society. [ABSTRACT FROM AUTHOR]

Our food system is facing an unprecedented challenge: feeding a fast growing population without depleting precious resources like energy, soil, and water. Furthermore, the increasing urbanization has rapidly exacerbated the gap between farm to plate, leaving cities vulnerable to changes in the production and supply chain, as demonstrated by recent pandemics and wars. In this context, emerging technologies that allow plants to grow in absence of soil, permit to produce food in high densely built-up areas, bringing food production right were most consumers live. These initiatives enter within the so called Building-Integrated Agriculture (BIA), which is referred as the practice of locating greenhouses and soilless plant cultivation technologies on top and inside mixed-use buildings to exploit the synergies between the building environment and agriculture, involving resource recovery such as water, energy and nutrient flows. This paper aims at determining strategies, objectives, and best practices of BIA projects through the review of 21 case studies, to understand how a new advanced and future-oriented agriculture applied within the cities borders, can possibly shape the urban built environment and food systems of the future. [Display omitted] • Building-integrated agriculture should not be considered just a food-related practice. • Integrated soilless food production exploits synergies between buildings & agriculture. • Building-integrated agriculture can enhance food security in urban areas. • To be effective, Building-integrated agriculture must overcome important challenges. • Economic & social advantages may come from a diffuse integrated urban food production. • Building-integrated agriculture projects still require a specific knowhow. [ABSTRACT FROM AUTHOR]

Circular economy (CE) is emerging in the construction industry because it attempts to substitute the linear economy model and promote sustainable development. While the CE principles have been applied at different scales, the construction industry's research efforts and practicalities remain limited and fragile. This study aimed at understanding the levels of circularity in the construction industry with a view to formulate viable recommendations required for achieving higher degrees of circularity. This aim is achieved by learning essential lessons from the manufacturing sector, which is considered one of CE's pioneering industries. In this paper, a scientometric review of CE research within the construction and manufacturing sectors was performed. The science mapping method was applied to quantitatively analyse relevant publications retrieved from Scopus and Web of Science databases. The results suggested that the construction industry centres on recycling and reuse as the main "R" strategies, while the manufacturing industry tends to achieve higher levels of circularity due to broader implementation of remanufacturing and industrial symbiosis (IS). The content analysis of some mainstream articles further identified the potential of adopting remanufacturing and IS in the construction sector. The findings suggested that higher levels of circularity in construction could be attained through the use of remanufactured components and recycled non-construction & demolition waste (CDW). An action plan comprising regulatory pull/push, business-driven, and technological push measures was formulated to guide researchers and practitioners to pursue looking-forward CE strategies. This review draws useful lessons from other sectors and offers fresh insight into ways of actualising circular construction. The findings of this study could serve as valuable references for improving the knowledge of policymakers and practitioners for promoting circular construction. [Display omitted] • The construction industry centres on recycling and reuse as the main "R" strategies. • The manufacturing industry achieves higher levels of circularity by implementing remanufacturing and industrial symbiosis. • The construction sector achieves higher circularity through regulatory pull/push, business-driven, and technological push. [ABSTRACT FROM AUTHOR]

The construction industry is a top priority in the transition to a circular economy (CE) due to the significant ecological footprint, wastage, and depletion of enormous resources. However, as an industry ill-reputed for a stringent change resistance, complex products, and among the least digitized in the world, the transition to CE in construction suffers unprecedented barriers. This study conducted a systematic review of fifty-three relevant studies to investigate and map the barriers to CE adoption in the construction industry. The analysis revealed a growing scientific research interest in the barriers from 2018 to 2022. The study established ninety-five (95) barriers to CE adoption in the construction industry, prioritized and ranked using citation frequencies. The study developed eleven taxonomies (i.e., typologies or categories) of the barriers, including cultural, market, knowledge, financial, management, regulatory, technological, supply chain, stakeholder, technical, and organizational barriers. The most persistent taxonomies of the barriers include financial, knowledge, regulatory, management, and supply chain barriers. The study discussed the possible interactions between the barriers responsible for the push effects and chain reaction mechanisms leading to CE failure in the construction industry and established the need for an integrated strategy to break the chain. It proposed a strategy map containing targeted intervention mechanisms and countermeasures to mitigate the vital few barriers in the various taxonomies of the barriers. The findings provide a holistic understanding of the main causes of the unsuccessful transition to CE in the construction industry and provide a sound basis to develop integrated strategies to improve CE adoption. • A systematic review is conducted to identify the barriers to CE adoption in the construction. • The review revealed ninety-five barriers to CE adoption in the construction industry. • The study categorized the ninety-five barriers into eleven taxonomies. • The persistent taxonomies include financial, knowledge, regulatory, and supply chain barriers. • The study developed a strategy map of countermeasures to mitigate the barriers. [ABSTRACT FROM AUTHOR]

The circular economy (CE) paradigm can eradicate the problems caused by the traditional linear economic approach adopted by the building industry. But the efforts to implement CE in the building and construction industry are fragmented and lack consensus. If improved, the ability to measure and report on progress can help in effectively transiting to CE. In this regard, wide-ranging building circularity indicators (C-indicators) have been proposed. However, the extant literature highlights that the comprehensive research on existing CE assessment tools in the building industry is still lacking, while policymakers (e.g., European Commission) and standards (e.g., ISO) have emphasized the need for a universally recognized circularity framework for buildings. To help this cause, this review inventories and critically analyzes 35 existing tools through an extended systematic literature review of 51 carefully selected documents from both academic and grey literature. It is found that there is a sharp increase in publications in recent years, with Europe leading the way. Along with the academic community, government agencies and consulting companies have also developed several C-indicators. The content analysis suggests that most indicators are quantitative and can vary in terms of the scale of application, the adopted CE scope and definition, and the underlying key performance indicators (KPIs). The descriptive analysis reveals that most indicators are in the developing stage and substantially stress recycling and reuse, overlooking some important aspects like energy, emission, and water. Innovative technical solutions like the design for adaptability and disassembly are excessively used to measure the circular potential of structures. The existing sustainability and circularity tools are seen as a good starting point for developing new frameworks. This extensive review and critical analysis provide a synthesis and explanation of the developing research theme of building C-indicators and highlight the remaining key challenges. The findings can drive the standardization of a universally accepted framework. • There is no common method to measure circularity in buildings. • 35 building specific circularity indicators are reviewed and analyzed. • There is lack of consensus on circular economy definition and scope in construction. • Most indicators focus on recycling and reuse with limited attention to other dimensions. • Design for disassembly and adaptability are important for building circularity. [ABSTRACT FROM AUTHOR]

• Potential recycling finely grounded MSWI-BA (GBA) in concrete mixtures as SCM. • GBA is mainly constituted by silica, calcium alumina and iron. • GBA incorporation as cement replacement provided workable pastes/mortars. • GBA decreased mortars mechanical strength, due to extra porous and cracking related to metallic aluminium and mitigated ASR. The present research explored the feasibility of using dry finely ground bottom ash (GBA) from municipal solid waste incineration as SCM for concrete mixtures in cooperation with a local waste management company, LIPOR. A first study was performed using GBA as a sole partial replacement for Portland cement in paste and mortar specimens. GBA showed both beneficial and detrimental effects on paste/mortar mixtures. In terms of fresh properties, water demand on paste and workability on mortar containing GBA as cement replacement kept the same as reference specimens paste/mortars. Setting time was not affected by GBA incorporation, and ASR expansion was mitigated. The disadvantageous effect, namely, mechanical strength loss on GBA mortar, was mainly due to metallic aluminium, found on the main oxide composition and SEM of GBA, which is associated with hydrogen gas evolution. Thus, the amount of aluminium content remaining in MIBA should be analysed even after the ageing process. [ABSTRACT FROM AUTHOR]

Earth is one of the oldest and till now intensively used natural building material. Around 30% of the world population still lives or works in buildings constructed out of earth. Most of them dwell in simple huts of rural communities or traditionally hand-crafted buildings. However, a growing number of people looking for healthy, environmentally friendly buildings in so called developed societies experience benefits of earthen construction materials. Due to the hygrothermal potential of clay, these benefits of earthen constructions include evaporative cooling during cooling periods and stable relative humidity levels indoors during the heating season. In addition, earthen building materials may contribute to the urgently needed circular economy, as earthen constructions like earth blocks or earth dry boards are reusable and earth plasters and mortars are replasticisable through the addition of water, as long as no chemical binder is added. Research gaps regarding physical properties, missing standardisation concerning building law and modern construction methods, and a limited number of manufacturers are hindering a wide application of earthen construction worldwide. Meanwhile, new digital production techniques evolve, which may elicit the potential of earth as future building material. Therefore, this Ten Questions article presents the state-of-the art and research gaps related to earth as building material in light of the potential of new digital production techniques like robotic fabrication or additive manufacturing. Such discussion includes new opportunities to combine the natural performance of the material with future-oriented construction systems and a new growing circular economy. • Earth is one of the oldest and till now intensively used natural building material. • Multidisciplinary view on earth as building material. • Influence of earth on IEQ and health can be positive. • Discussion of the potential of new digital production techniques. • Potential for circularity exists but needs further research. [ABSTRACT FROM AUTHOR]

• Ecodesign method proposed to be applied at the experimental stage of construction materials development. • Application of the ecodesign method in the production of mortar made with ornamental rock wastes. • Cradle-to-gate life cycle assessment of mortars with cutting and polishing wastes. • Reduction of life cycle environmental impacts to produce the ecological mortars. • Physical and mechanical analyzes of the mortars. This paper proposed and tested a method to support the early stages of construction materials ecodesign, with an application focus on the production of mortar made with ornamental rock waste. The method was organized in four phases. In Phase 1, materials (sand and cement) and waste for mortar production were characterized. In Phase 2, a cradle-to-gate Life Cycle Assessment (LCA) was developed to compare the environmental performance of mortars made with sand and cement replacements, in different proportions (0, 10, 20 and 30% by weight), by cutting (CW) and polishing (PW) wastes. In Phase 3, mortars were produced for the best environmental benign configurations of CW and PW applications, and their physical (consistency index, bulk density, open porosity, dried mass, saturated mass and capillarity) and mechanical (flexural and compressive strength) properties were evaluated. In Phase 4, eco-efficiency indicators were calculated to select the best ecodesign scenarios. Results indicated that only the sand replacement can considerably reduce environmental impacts in mortar production. The greatest impact reduction was for the Fossil Depletion category, which was up to 25% reduced by including 30% of CW (CW-30% scenario). The physical–mechanical analysis reveals that most of mortars properties were not significantly modified with the different incorporation levels of the wastes, but CW-20% showed the best overall performance. Finally, CW-20% and CW-30% were considered the most eco-efficient scenarios for the development of mortars on experimental scale since they showed satisfactory properties while keeping a low level of environmental burdens in a life cycle approach. This agile ecodesign approach could be used by companies that understand the importance of evaluating environmental impacts during experimental stages of tests of construction materials development. [ABSTRACT FROM AUTHOR]

In the last couple of years, actors in the construction industry have shown an increasing willingness to move towards circular businesses. However, many consider circular construction to be a more expensive option, which makes actors reluctant to invest in circularity. This study contributes to the existing literature by relating the Level of Circularity (LoC) for a one-family house to its Life Cycle Costs (LCC). Using design-orientated research, the design of the one-family house was altered to gradually increase its LoC. The results revealed that it is possible to double the LoC to 0.41 compared to the initial design (LoC = 0.20) without increasing the LCC. Furthermore, the measures do not require radical changes to the design and construction process. Rather, it only requires replacing virgin materials with recycled or biological materials, and using building products that can be disassembled relatively easily. The results also revealed that increasing the circularity level further resulted in a sharp increase in product costs, and therefore an increase in LCC. This makes it less economically attractive for construction companies. Therefore, we suggest starting with relatively easy measures, which can already double the current circularity level of typical one-family houses. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The challenges of sustainable construction, industrial growth and importance of resource efficiency are clearly recognised by the UK government and are now at the forefront of strategy and policy. A critical component of the government's sustainability strategies concerns way in which construction and demolition waste (C&DW) is managed. In this study a mixed method approach was adopted to investigate current practices of C&DW management and circular construction (re-use, recycle and recovery of materials) concept awareness in the UK. Relevant stakeholders from the construction industry (contracting, demolition and C&DW organisations) were selected and their views solicited on arguments about circular construction to help establish common visions and further encourage sustainable behaviour across the sector. The study revealed that legislation by the government on the re-use and recycling threshold for every new project can substantially improve circularity within the built environment. More specifically, focus should be on smart dismantling of buildings and ways of optimising cost effective processes. This will enable fair competition between stakeholders and eventually lead to investments in innovative approaches for resource recovery from C&DW. Further incentives and appreciations from government should also be given to stakeholders who are innovating and setting benchmarks in circular construction. This can lead to harmonised technological and non-technological solutions, closed-loop material processes and a circular economy. [ABSTRACT FROM AUTHOR]

'Sustainability', 'circular economy', 'circular construction' have received increasing attention in the last decade. However, their interpretation is often unclear, as is the way a certain study fits into these research fields. In this paper, therefore, first a definition of both 'sustainability' and 'circular economy' is proposed. It is concluded that sustainability is the goal, while the circular economy is a means to achieve a more sustainable economy. Subsequently, the application of the circular economy in the construction industry is investigated, with a special focus on bridge construction. Reason is that, for instance, many concrete pedestrian bridges currently find themselves in the end-of-life phase, are demolished and often merely rebuilt, with a lot of material and energy loss as a consequence. An investigation of the available circular construction principles is therefore performed in order to determine certain limitations and gaps for future research and to stipulate the path to be followed towards circular bridge construction. This is necessary in order to prevent the same cycle of demolition and replacement from being run through again in a few decades. It is concluded that the meso-scale, the construction in general, is rarely discussed. Yet, an in-depth investigation is necessary in order to develop specific design strategies for circular bridges. A certain standardisation scheme to facilitate circularity, needs to be developed. This scheme should, however, still allow enough architectural freedom. Additionally, this scheme needs to be accompanied by, to be developed, meso-scale circularity indicators to effectively assess the eventual circularity of a bridge. • Sustainability is the goal, circular economy is the means to this end. • Specific design strategies for circular bridge construction are to be developed. • The meso-scale, the construction, needs to be elaborated thoroughly. • Circularity assessment requires a different approach from sustainability assessment. [ABSTRACT FROM AUTHOR]