Circular Construction Research Articles

Innovative valorization of biomass waste-derived sodium silicate for geopolymer concrete synthesis: Sustainability assessment and circular economy potential

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 CO2 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.

A concrete answer for circular construction: three prototypes reusing saw-cut elements

Existing concrete buildings should be retained for as long as possible to reduce the environmental burden of demolition and new construction. However, when urban pressure makes demolition unavoidable, salvaging and reusing concrete elements elsewhere in new structures, rather than reducing them to rubble, efficiently prolongs the use of existing resources at their highest structural value. Concrete reuse is not a new approach: pioneer cases have demonstrated its potential, but broader adoption has still not been seen across the wider industry. Three prototypes recently built by Ecole Polytechnique Fédérale de Lausanne researchers and students in Switzerland demonstrate the feasibility and potential of reusing elements saw-cut from cast in situ concrete structures. The prototypes deal with different scales of elements, from small blocks to large slab elements and 3D assemblies. Lifecycle assessments confirm that reusing concrete elements drastically reduces the upfront global warming potential of new construction, providing a new lower-bound benchmark for sustainable, circular construction.

Tied islands: The role of organizational members in knowledge transfer across strategic projects

Transferring knowledge across strategic projects is challenging. This study investigates how informal practices of members of the parent organization shape the transfer of knowledge across strategic projects. This was addressed through an in-depth case study of strategic projects in an innovation trajectory of a large public organization aiming to accelerate to transition towards circular construction. We identified five disabling practices: shaming and blaming, disconnecting, holding onto the department and project boundaries, fostering one-way relationships and avoiding internal conflict. Furthermore, we identified three enabling practices: supporting circular projects, sharing similarities across projects and integral visioning. The results contribute to the cross-project knowledge transfer literature by showing how members of partner organizations can enable or disable knowledge transfer across strategic projects. Furthermore, the results contribute to the strategic project literature by illuminating the importance of informal practices of members of the parent organization.

An assessment of barriers to digital transformation in circular Construction: An application of stakeholder theory

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.

Mapping out focus for circular economy business models (CEBMs) research in construction sector studies – a bibliometric approach

Purpose The circular economy business models (CEBMs) provide ways for firms operating in the construction industry to move from a linear to a circular approach. Thus, this study aims to explore CEBM research within the construction sector to show the focus area of studies, highlighting new areas that require attention. Design/methodology/approach This study adopted a bibliometric approach, using the Scopus database as the data source. The keywords used for paper extraction from the database were “circular economy business” OR “circular business” AND “model” OR “models” AND “construction industry” OR “building industry”. The VOSviewer software was then used to prepare a co-occurrence and co-authorship map based on the bibliographic data gathered. Findings The study’s findings reveal five research clusters in the construction industry. These clusters include circular construction intelligence, modular business modelling, eco-construction, sustainable construction economics and smart energy-efficient buildings. The two most cited scholars had two publications each, while the top journals are the Journal of Cleaner Production and Sustainable Production and Consumption. This study concludes that there is a need for research within the construction sector to focus on CEBMs’ archetypes and frameworks. This will enable a smooth transition from linear to circular business models in the sector. Research limitations/implications The information was gathered from a single database, Scopus; hence, using other databases, including Web of Science, Google Scholar and Dimensions, might produce more articles for examination and, consequently, different findings on the subject under investigation. Practical implications These findings would assist researchers in considering the areas mentioned, which are yet to receive attention, and, by extension, enhance economic development while maintaining environmental sustainability. Originality/value This paper made a significant contribution to the body of knowledge by identifying scholars and platforms that have been instrumental in advancing CEBM research and highlighting new areas that require attention in the construction sector.

Spatial optimization of circular timber hubs

In the European Union, construction is responsible for 36% of CO2 emissions and 40% energy consumption. The reuse of construction materials has been receiving increasing attention, including regulations established by the European Union, and cities establishing goals to reuse construction materials. This is the case for Amsterdam, which established the goal of reusing 50% of construction materials in new construction by 2030. Part of the challenge of reuse of construction materials in urban areas is to optimize the waste-to-resource loops: finding the optimal scale and location for circular construction hubs—facilities that collect, store, and redistribute construction waste as secondary construction materials. In this paper, we use the supply and demand of timber construction materials in Amsterdam as a case study to find the optimal scale and location for construction hubs. We used the spatial simulated annealing algorithm as an optimization method for balancing the trade-off between small and large-scale hubs, using cost-effectiveness to compare potential locations and identify the optimal solution. We found that the optimal number of hubs for our study area is 29, with an average service radius of 3 km. This study has implications for policymakers, urban planners, and companies seeking to implement circular economy principles.

Evaluating the key competency skills of construction professionals for the attainment of circular construction in developing economies

Climate change has become a global problem, and the construction industry (CI) contributes significantly to this challenge. To circumvent these effects, the circular economy (CE) concept should be implemented in the CI. Developing economies could possess significant potential for implementing CE principles to attain sustainability, particularly in the CI. However, achieving this would require professionals in the CI to adopt some key competencies that should propel success in circular construction. Therefore, this study aims to identify the key competencies required by professionals in the CI to attain circular construction using Ghana as a case study. A quantitative research approach and purposive sampling technique were adopted. After an extensive literature review which showed several key competencies, a cross-sectional survey was conducted among five large construction firms and fifty-two responses from experienced professionals in the industry were obtained. Relative importance index and principal component factor analysis (PCFA) were adopted to evaluate the obtained data. Key significant competency skills for construction professionals to propel circular construction were identified such as specification writing for components and materials, designing for multiple-use cycles, and designing for near-zero energy buildings, among others. Three components were extracted from the PCFA which served as the guidelines for enhancing the competency skills of construction professionals namely, implementing sustainable circular practices, embracing sustainable operations management techniques, and adopting sustainable design principles. In addition, to enhance its practical implications, a competency implementation framework was also developed for construction professionals of developing economies to propel the adoption and evaluation of their competency skills toward circular construction.

Reuse of cut concrete slabs in new buildings for circular ultra-low-carbon floor designs

The study explores an original idea that responds to the urgent need to reduce the detrimental environmental impacts of load-bearing floor construction in new buildings by reusing saw-cut reinforced concrete (RC) pieces salvaged from soon-to-be demolished structures. Cutting and reusing large RC pieces rather than crushing them to rubble is an untapped emerging circular construction method with a high potential for reducing waste generation, natural resource consumption, and upfront greenhouse gas emissions. Through an iterative design and analytical process, the study demonstrates how discarded cast-in-place RC floors can be cut and reused to build new low-carbon, little-extractive, load-bearing building floors. The study provides two new floor design solutions that valorise frequently discarded construction components (reinforced concrete slabs and steel profiles), combining construction technologies already used by the industry. The parametric design of 20′280 combinations of donor and receiver structures and their environmental analysis through Life-Cycle Assessment show that the new floor systems have shallow detrimental environmental impacts, with a reduction of upfront greenhouse gas emissions averaging 80 % compared to conventional practice. Floor-system solutions as low as 5 kgCO2e/m2 have been obtained. Structural assessments additionally show that flat slabs that are currently demolished meet the structural requirements at the preliminary design stage for reuse in new office or housing buildings. In particular, thanks to mandatory minimum reinforcement, 18-cm thick or thicker flat slabs built in Switzerland after 1956 and spanning up to 4 m are expected to be technically reusable as-is over their entire span. Overall, this study sets up a new benchmark for innovative floor systems with minimum environmental impacts and calls for considering soon-to-be demolished RC structures as mines of valuable construction components.

Architectural Perspectives on Wood Reuse within Circular Construction: A South–Central European Study

This study explores the perspectives and practices of architects regarding the reuse of wood in construction across five South–Central European countries: Slovenia, Serbia, North Macedonia, Bosnia and Herzegovina (BiH), and Montenegro. Based on a survey of architectural professionals, this research explores their attitudes, challenges, and motivations for using reclaimed wood, with a focus on circular construction principles. Key findings reveal unanimous agreement among respondents that both their profession and government entities inadequately support or promote wood reuse within the context of circular construction. While architects value reclaimed wood, there are country-specific variations. Environmental benefits, unique aesthetics, historical value, and sustainability are cited as primary motivators for reclaimed wood use. Additionally, respondents emphasize the ecological aspect as the most important consideration in wood product reuse, followed by economic and technological factors. Common concerns revolve around the long-term quality and maintenance of wood products. This research provides insights into the challenges and opportunities surrounding reclaimed wood use in South–Central Europe, highlighting the need for support mechanisms and increased awareness to advance circular construction practices in the region. These findings can have implications for architects and investors by identifying market opportunities, promoting eco-friendly practices, and providing valuable insights for future building designs with a focus on reclaimed wood elements within circular construction.

Geopolymer as stabilising materials in pavement constructions: A review

Construction in weak or soft soil needs soil stabilization. The most popular stabilizers are fly ash, cement, and lime to stabilize a road pavement's base, subbase, and subgrade courses. Cement is a crucial component of many construction materials for the entire world. However, it has particular environmental problems and the long-term durability of soil-cement combinations, which impacts life. The production process of this cement requires a tremendous amount of energy and produces a large quantity of carbon dioxide, resulting in environmental pollution. To get out of this problem, researchers have found an alternative by using geopolymers. This paper gives a state-of-the-art review of geopolymer-based soil stabilization for road pavements. It discusses how weak and soft soils are stabilized with waste materials forming geopolymers, thus enhancing their properties to use as pavement materials. The paper also reviews the utilization of various wastes as base materials for geopolymer towards stabilizing soil for road construction as circular construction. Towards end the paper highlighted the future research agendas.

Unreinforced concrete masonry for circular construction

This paper proposes an effective approach to realise circular construction with concrete, and shows Unreinforced Masonry as a foundational building block for it.The paper outlines the importance of circularity in building structures. It specifically focuses on the impact of circular construction with concrete on improving the sustainability of the built environment in a rapidly urbanising world economy. Subsequently, the relevance of principles of structural design and construction of unreinforced masonry to achieve circularity is articulated. Furthermore, the paper presents and summarises recent developments in the field of Unreinforced Concrete Masonry (URCM) including digital design tools to synthesise structurally efficient shapes, and low-waste digital fabrication techniques using lower-embodied-emission materials to realise the designed shapes. The paper exemplifies these using two physically realised, full-scale URCM footbridge prototypes and a commercially available, mass-customisable building floor element, called the Rippmann Floor System (RFS).The paper also outlines the benefits of mainstream, industrial-scale adoption of the design and construction technologies for URCM, including accelerating the pathway to decarbonise the concrete industry. In summary, the paper argues that URCM provides a solution to significantly mitigate the carbon emissions associated with concrete and reduce the use of virgin resources whilst retaining its benefits such as widespread and cheap availability, endurance, fire safety, low maintenance requirements and recyclability.

Compared Environmental Lifecycle Performances of Earth-Based Walls to Drive Building Envelope Design

Raw earth has useful applications in contemporary buildings as a sustainable and circular construction material. The present study aims to assess the environmental performance of several earth-based wall systems with similar thermal performance, through a life cycle thinking approach. In particular, a life cycle assessment is developed for (a) unstabilized rammed earth (produced in situ), (b) compressed earth blocks (prefabricated in the factory), (c) stabilized rammed earth and (d) light earth, all combined with biobased (natural fibers, e.g., lime hemp, cork) and/or conventional materials for building insulation. Results show benefits in terms of avoided carbon emission, water footprint and embodied energy throughout the production chain and highlight limits and potential improvements. In addition, the CO2 offset by crops is also estimated based on carbon embedded in natural fibers. In particular, light earth wall systems are the most suitable to minimize environmental impacts, while massive constructive technologies (as unstabilized rammed earth) show a higher dynamic thermal performance for intended use in Mediterranean climates.

Potential of BREEAM-C to support building circularity assessment: Insights from case study and expert interview

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.

Circular Material Usage Strategies and Principles in Buildings: A Review

Building construction accounts for a significant proportion of global greenhouse gas emissions, raw material extraction, and waste production. Applying circular economy (CE) principles in the building construction industry would considerably reduce these values. However, uptake by the industry is relatively slow, which is largely attributed to sectoral barriers, including limitations in knowledge and experience. This review paper aims to assess and contribute to diminishing these obstacles by offering a comprehensive review of circular material usage principles and strategies within the construction sector. Opportunities and facilitators of change are also presented, including innovations and emerging technologies in recycling, digitization, robotic systems, novel materials, and processing. Finally, four case studies demonstrate the application of circular theory via a novel block system, recycled aggregate, modular kitchen reuse, and an energy efficiency retrofit. The conclusions show that future efforts should prioritize the development of strong regulatory frameworks, awareness initiatives, and international cooperation. In this regard, the integration of technological advancements, such as AI, robotics, and blockchain, is essential for optimizing waste management efficiency. Furthermore, education on circular practices plays a critical role. Through global collaboration, standardizing circular construction approaches can promote a more sustainable and resilient building construction industry.

Pathways to decarbonization, circular construction, and sustainability in the built environment

PurposeThe built environment is responsible for approximately 40% of the world’s energy consumption, 30% of raw material use, 25% of solid waste, 25% of water use, 12% of land use and 33% of greenhouse gas emissions. Thus, environmental improvement and decarbonization are becoming increasingly critical objectives for the construction industry. Sustainable construction can be achieved through several practices, including: considering life-cycle assessment, circular construction, resource efficiency and waste management and providing eco-efficient materials, reducing energy demands and consumption and incorporating low-carbon technologies and renewable energy sources. To achieve sustainable construction goals, it is critical to educate the future workforce about decarbonization, circular construction and how to overcome the challenges involved in transitioning to sustainable construction. This study aims to understand the gap in student knowledge related to decarbonization and circular construction and the importance of incorporating these topics in civil engineering and construction management curricula.Design/methodology/approachThis study surveyed 120 undergraduate and graduate students at one of the largest minority-serving institutions in the USA to understand the gap in student knowledge related to decarbonization and circular construction as well as the importance of incorporating these topics in civil engineering and construction management curricula. The authors conducted several statistical measures to assess the consistency, reliability and adequacy of the sample size, including the Kaiser–Meyer–Olkin measure of sampling adequacy, the normality test to evaluate the appropriateness of using an ordered probit regression analysis and a multicollinearity test to observe the correlation between independent variables. The data was analyzed using ordered probit regression analysis to investigate the need for a curriculum that serves in educating students about decarbonization and circular construction.FindingsThe results of this research highlight the gaps in students’ knowledge pertaining to sustainable practices and the importance of providing future construction workforce with such knowledge to tackle global inevitable challenges.Originality/valueThe findings of this study contribute to sustainable construction bodies of knowledge by advocating for a reformed curriculum to prepare the future workforce and adopt less carbonized, more circular approaches within the engineering and construction industry.

Exploring the opportunities and challenges of transitioning to a circular economy in the construction industry

The construction industry is one of the largest industries in the world, responsible for global waste and pollution. As such, there is a growing interest in transitioning to a circular economy, which aims to reduce waste and increase resource efficiency. The purpose of this study is to investigate the opportunities and challenges in transitioning to circular construction industry in Albania. The research method is qualitative and is based on semi-structured interviews with respondents representing different roles in the construction industry. The findings show that construction stakeholders are primarily driven by mandatory laws and regulations in embracing circular practices. The industry faces significant challenges in effectively adopting and implementing circular economy in its managerial processes and to overcome these difficulties, the study highlights the importance of collective efforts, involving key players such as architects, designers, contractors, and policymakers to formulate and enforce policies that encourage circular design and construction methods, while fostering circular business models. The study contributes to the existing literature by shedding light on the motivations and challenges faced by contractors in transitioning to a circular economy, and provide valuable insights for policymakers, industry stakeholders, and academics to support the sustainable development of the construction industry in Albania and beyond.

Reusing and recycling timber for a circular construction

With a budget of circa 20 million euros and 30 partners, SirkTRE is one of Norway’s biggest R&D projects of its kind. It is managed by Omtre AS and counts 6 work packages. Ola Rostad is the leader for task SirkGLOBAL, the work package which is responsible for networking and outreach internationally.

Modelling and Analysis of Pufferfish (Torquigener albomaculosus) Circular Nest on Seafloor

This study analyzed the structural features of the circular structures built by the male pufferfish (Torquigener albomaculosus) on the seafloor. This impressive circular structure which is built by male pufferfish exists in different depths and sizes on the seafloor. One of the objectives for the male pufferfish constructing these circular structures is to influence the opposite sex. The morphological features of these circular structures built on the sea floor were analyzed mathematically. This analytical study was performed using photographs received from the sea floor as well as the ratios of circular formations discovered in this context. During the image analysis, the histogram equalization method was used to improve the visuals and reveal the patterns of circular structures. The Hough transform method, which is commonly used in the determination of circular structures, was used in the process of precisely determining the dimensions of the obtained circular structures. The circle size ratios obtained from the images and the circular structure dimension ratios obtained from the observation were examined. When the ratio analysis results from 2 images and 6 observation data were examined, it was observed that significant traces of the golden ratio were seen in these nested circular structures. According to this study’s analysis of the pufferfish nest, which demonstrated proper development, the percentage difference between the golden ratio and the radius of the circular structures was determined to be as low as 0.185%. Additionally, these circular constructions were recreated in 3D while preserving their proportions, and their hydrostatic pressure characteristics were analyzed depending on their actual depths on the seafloor.

Local recycling and reuse of concrete and soil: The societal impact of double-loop learning from circular urban transformation projects

The article presents certain findings from a large European research and development project aiming to generate societal impact through multi-stakeholder collaboration based on circular economy principles in the built environment. In the project, eight apartment buildings were demolished, and recycled aggregate concrete was used to cast the foundation for a new city hall being constructed nearby. Additionally, excavated soil from the construction of the city hall was transported to the urban development site where apartment buildings had been demolished, and the excavated soil was used in the terrain for the new urban development in the area. The local reuse of excavated soil significantly reduced transport volumes as the soil would otherwise have been transported long distances out of the city. The primary impact of the project was the direct environmental effects associated with the local concrete and soil recycling. The secondary impacts were linked to improved coordination and management of circular construction projects in the municipality through knowledge and competences being developed during the project (single-loop learning). Finally, the project also created awareness in the municipal organisation about strategic and organisational changes needed to facilitate future circular construction projects (double-loop learning).

The Sustainable School as an Venue for Environmental Education

Sustainable schools are energy-efficient, environmentally friendly buildings that provide a healthy living environment and promote environmental education. Reference examples from abroad show the characteristics of sustainable schools as an expression of ecological design, circular construction and the integration of learning environments with nature and sports activities. We were interested in whether teachers recognize the sustainable features of the schools they teach in and to what extent they integrate them into the curriculum. We conducted a short survey in some Slovenian elementary school and came to the conclusion that teachers are mostly unaware of the sustainable features of the schools and do not include them in their learning processes. The results of the study can be used as recommendations for the introduction of sustainable school principles into the pedagogical and architectural profession.