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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]

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]

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]

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 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]

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]