Demolition Waste Management Research Articles

Improving the decision-making for sustainable demolition waste management by combining a BIM-based life cycle sustainability assessment framework and hybrid MCDA approach

Increasing efforts have been devoted to promoting sustainable demolition waste management (DWM) from a life cycle-thinking perspective. To this end, facilitating sustainability-oriented decision-making for DWM planning requires a sustainability assessment framework for assessing multifaceted criteria. This study develops a building information modelling (BIM)-based DWM sustainability assessment approach to facilitate the life cycle assessment (LCA) and decision-making by coupling the enriched Industry Foundation Classes model with hybrid multi-criteria decision-aiding (MCDA) methods using Dynamo visual scripting. To streamline the data-intensive LCA process, this study enriched the BIM properties and accommodated them into the LCA data template to enhance data interoperability, thus achieving seamless data transfer. Moreover, hybrid MCDA methods are integrated into the decision-making workflow for DWM scenario ranking. A pilot study is employed to verify the applicability of the decision-aiding framework. The results unveil that the sustainability score ascended with the recycling rate. The optimal DWM alternative with the highest recycling rate yields the highest sustainability score at 91.63. Conversely, a DWM alternative reflecting the ‘status quo’ in China’s recycling industry has the lowest score at 8.37, significantly lower than the baseline scenario with a 50% recycling rate. It is worth noting that the ‘growth curve’ of the sustainability score continuously flattens as the target recycling rate escalates. The increment in recycling rate from the ‘Australian standard’ scenario to the optimal scenario is 18.4%, whereas the sustainability score merely increases by 2.3%, signalling that the former scenario arrived at an optimum point for maximising the cost-efficiency of DWM under the predefined framework and contexts.

Application of Building Information Modelling in Construction and Demolition Waste Management: Systematic Review and Future Trends Supported by a Conceptual Framework

The architecture, engineering, construction, and operations industry faces an urgent need to enhance construction and demolition waste management in urban areas, driven by increasing demolition and construction activities and a desire to align with sustainable practices and the circular economy principles. To address this need, a systematic literature review on the building information modelling methodology was conducted, employing a structured protocol and specific tools for the analysis of academic studies, based on PRISMA guidelines and StArt software (version 3.4 BETA). Ninety relevant studies published between 1998 and 2024, were analysed and selected from the Web of Science, Scopus, and Engineering Village databases. Findings indicate that China leads in publications with 34%, followed by Brazil (8%) and the United Kingdom (7%). The analysis emphasises the use of drones and LiDAR scanners for precise spatial data, processed by 3D reconstruction tools like Pix4D and FARO As-Built. Revit excels in 3D modelling, providing a robust platform for visualisation and analysis. Visual programming tools such as Dynamo automate processes and optimise material reuse. The study presents a conceptual framework that integrates these technologies with the principles of the circular economy, clarifying the interactions and practical applications that promote the sustainable management of demolition waste from urban buildings and process efficiency. Although the approach promotes material reuse and sustainability, it still faces barriers such as the need for waste segregation at the source, the adaptation of innovative technologies, like the iPhone 15 Pro LiDAR and thermal cameras, as well as associated costs. These factors may limit its adoption in larger-scale projects, particularly due to the increased complexity of buildings.

The Potential of Wood Construction Waste Circularity

Wood construction waste circularity presents enormous potential to significantly de-crease total greenhouse gas (GHG) emissions in the European Union (EU). Latvia could become a frontrunner due to its historic relationship with forestry, wood construction practises and unused potential of the innovative application of wood. This research examines what the potential of “circular wood” in Latvia is, how ready the Latvian wood house construction sector is to engage in a circular economy and wood waste circularity and whether the legal framework is ready to support wood waste management in the country. This study presents a combined approach for systematic wood construction product circularity assessment that includes a review of existing EU and Latvian frameworks for construction and demolition waste (CDW) management and wood construction, a general analysis of wood waste recycling systems and technologies, a quantitative data analysis of construction waste management in Latvia and qualitative data analysis of the Latvian wood house construction sector, and interviews with a focus group of Latvian wood industry representatives. The Latvian scope has allowed us to clarify the pattern methodology and impact points to be replicated, tested and measured further on a broader scale, in other countries, or throughout the whole EU. The main findings reveal a potential life cycle assessment (LCA) verifying the circularity of wood and limitations of wood construction waste circularity in Latvia in terms of wood house construction industry readiness and a legal framework as well as overall social prejudices for circular construction. Findings indicate an overall awareness and level of willingness to participate and engage in the circular construction models among Latvians; however, proactiveness and support (legal and financial) is expected from the government and municipalities. The recommendations point towards improvements in wood waste data management, the wood construction sector and the overall impact on sustainable development goals.

Comparative LCA-MCDA of high-strength eco-pervious concrete by using recycled waste glass materials

Sustainable management of construction and demolition (C&D) waste and waste glass (WG) presents a significant challenge in densely populated regions like Hong Kong. While the potential for using WG in concrete is acknowledged, there is limited research on how to optimally use these materials to achieve sustainability, cost-effectiveness, and mechanical integrity. This study addresses these challenges by employing an integrated life cycle assessment and multi-criteria decision analysis (LCA-MCDA) within a cradle-to-gate scope, utilizing site-specific data. The VIKOR method, known for its robust decision-making capabilities in complex environmental assessments, was used to identify optimal concrete mixtures based on environmental, economic, and mechanical performance. The results indicate that replacing 25% of natural aggregate with recycled WG materials provides the best balance across the evaluated criteria. Furthermore, additional environmental benefits can be achieved by substituting natural aggregates with recycled waste concrete aggregates. This research underscores the importance of life cycle thinking in construction materials decision-making, demonstrating that significant use of recycled WG reduces energy consumption and greenhouse gas emissions, offering a sustainable alternative to conventional concrete.

Digital Technologies for Promoting Construction and Demolition Waste Management: A Systematic Review

The increasing concern about the environment has led to the necessity of ensuring efficient Construction and Demolition Waste Management (C&DWM) in the built environment. Despite the extensive research on C&DWM, the industry still faces significant challenges, including inefficiencies, high costs, and environmental impacts. Meanwhile, incorporating digital technologies (DTs) has emerged as a way to eradicate the challenges of C&DW. In response to the knowledge gap, in this research, we conducted a systematic literature review (SLR), incorporating bibliometric, text-mining, and content analysis to meet the research objectives. In total, 126 papers were retrieved from the Scopus database and transferred into VOSviewer to conduct the bibliometric analysis. The findings identified seven specific DTs, namely, blockchain, Internet of Things (IoT), Artificial Intelligence (AI), Machine Learning (ML), Robotics, Computer Vision (CV), and Building Information modeling (BIM). This study demonstrates that these technologies play a significant role in promoting efficient C&DWM in the construction industry. The study’s implication lies in its potential to guide industry stakeholders and policymakers in promoting the use of DTs and overcoming the barriers to their adoption, thereby facilitating more efficient and sustainable C&DWM practices. Finally, the findings of our research indicate possible future research directions for promoting DTs for C&DWM and eradicating the barriers to efficient implementation.

Construction and Demolition Waste Management and Artificial Intelligence – A Systematic Review

Objective: The present study aims to identify how Artificial Intelligence (AI) techniques are being employed in Construction and Demolition Waste (CDW) management through a systematic review. Method: The methodology adopted for this research comprises a systematic review of 37 papers focusing on AI applications in CDW management. The search for scientific papers was conducted using the Scopus and Web of Science databases. We extracted data on the year of publication, country of the first author, main models used, performance metrics, dataset size, dataset source, and key gaps and limitations identified by the authors. Results: The incorporation of AI in CDW management is relatively recent, with a significant rise in publications noted from 2021. Most papers have a Chinese first author, and the most frequently used ML algorithms were the RF, GBM, CNN, and ANN. Three primary research topics were identified: CDW Generation Prediction, CDW Classification and Identification, and Decision Support Systems and Logistics. Despite the advancements, challenges such as insufficient data for model training and limited interpretability of AI models persist. Research Implications: The research provides insights into how AI can enhance recycling processes and supports the integration of AI models with Decision Support Systems and logistics to promote sustainability and circularity in construction practices. Originality/Value: The research underscores the potential for AI to transform CDW management practices, offering valuable perspectives for both academic research and practical applications.

Sustainable management of construction and demolition waste in Bangladesh to promote resource recycling

ABSTRACT This study conducted during the fiscal year of 2022–2023 endeavors to offer waste generation rates (WGR) for different Construction and Demolition Waste (CDW) materials and analyze the financial and environmental benefits of CDW recycling at a national level. Findings from the study reveal that CDW in Bangladesh mainly consists of concrete (56%), brick (15%), mortar (9%), metal (6%), and ceramics (6%). Additionally, the collective CDW produced in six major cities studied totals 3.71 million tons (MT). The WGR of CDW is assessed through regression analysis. The mean WGR for Construction and Demolition activities in the fiscal year 2022–2023 are notably recorded at 64.68 kg/m2 and 1626.97 kg/m2, correspondingly for the 12 city corporations. The study highlights the potential for entrepreneurial initiatives in recycling materials like concrete, brick, mortar, metal, ceramics, and timber, leading to reduced CO2 emissions and energy consumption. The estimated economic value of recycling concrete, brick, and metals in major cities is approximately 104.5 million USD and 0.45 MT of CO2 reduction from recycling brick and metals from major cities.

Assessment and management of construction and demolition waste in tier 2 cities of Karnataka, India: a case study of Hubli-Dharwad and Davanagere.

The present study examines the current practices for managing construction and demolition waste (CDW) in two tier-2 cities of Karnataka state: Hubli-Dharwad and Davanagere. The research highlights the quantification, characterization, and effective management strategies for CDW. CDW dumping sites were identified through field visits conducted across all wards of the cities and recorded using a mobile-based app. At each site, data were collected on the types of vehicles dumping CDW, the frequency of dumping, the volume of waste in the vehicles, and the quantity of CDW removed for reuse. The dumping sites were categorized into large, medium, and small based on the area and volume of waste. In total, 130 unauthorised dumping sites were identified in Hubli-Dharwad and 62 in Davanagere. The study estimated that Hubli-Dharwad generates approximately 607 tonnes per day (TPD) of CDW, while Davanagere produces around 287 TPD. The characterization of CDW revealed that in Hubli-Dharwad, CDW consists of 14.4% concrete, 25.5% brick and mortar, 39.1% soil and aggregates, and 20% other materials. In Davanagere, the composition includes 19% concrete, 29% brick and mortar, 38% soil, and 14% other materials. Based on these findings, the study proposes a system for the collection and transportation of CDW and recommends suitable recycling technologies. While the approach outlined in this paper is well-suited for urban local bodies to assess CDW, the data on CDW reuse and recycling is primarily based on informal practices. This makes accurate quantification challenging and subject to variation over time due to a lack of regulatory oversight. Additionally, the study provides only a snapshot of CDW generation and management at a specific point in time, potentially missing seasonal variations or long-term trends in waste handling.

Evaluating the carbon emission reduction in construction and demolition waste management in China

Construction and demolition waste reduction (C&DWR) is an important measure to protect the environment and promote sustainable development in the construction sector. The present policy in China remains a lack of emphasis on carbon tax and penalty for reducing construction waste. This paper proposes a construction and demolition waste (C&DW) management model to identify the waste reduction effects of various policies in China. It simulates the effects of single policies and combined policies on waste reduction and carbon emission by using the approach of integrating system dynamics and grey model theory. The results reveal that: (1) Penalties can effectively reduce the amount of illegal dump waste and carbon emissions from illegal dump waste, with an appropriate penalty value (in Chinese CNY) suggested as ∈160,320. (2) Subsidies can vastly increase the amount of waste recycled and a carbon tax can reduce carbon emissions; the recommended values are suggested as subsidies ∈30,45 and carbon tax ∈40,70. (3) Compared to other policies, the combined policy of penalty–waste disposal charging fee–subsidy–carbon tax (160, 60, 45, 70) achieves the greatest environmental benefits in terms of reducing waste and carbon emission. (4) Governments should improve waste minimization incentive policies and gradually introduce trials for a carbon tax policy, encourage the use of digital governance combined with blockchain technology to regulate C&DW. These findings provide valuable insights for policymakers to develop effective waste reduction strategies and promote sustainability through the implementation of C&DWR theories.

Сharacteristics of demolition waste management in the regions of Ukraine

The volume of waste left from war-related destruction amounts to 10-12 million tons per year. Such volume is comparable to the annual volume of municipal solid waste generated in Ukraine. This situation led to formation of unauthorized landfills and complicated the existing problem of industrial, consumer, construction and demolition waste management. Consequently, the issue of destruction waste management became a pressing environmental and socio-economic problem. The objective of this research is to assess the characteristics of destruction waste management in the regions of Ukraine. Destruction waste is generated during construction of new buildings and public structures, as well as during renovation or demolition of existing buildings and structures; including general-use facilities. It is estimated that, before the war, nearly 7 million tons of construction and demolition waste was generated annually, with more than 50% being transported to municipal solid waste landfills. Specialized landfills for its disposal were virtually non-existent in the regions of Ukraine, so this waste, despite its resource value, was taken to municipal solid waste landfills or unauthorized dumps. Some components of construction and demolition waste are toxic. Destruction waste includes parts (fragments) of damaged (destroyed) objects, as well as materials and items that were inside or next to such objects at the time of damage (destruction) and/or during disassembly activities, including those that fully or partially lost their consumer properties and cannot be reused at the place of their origin or discovery. Destruction waste pollutes the environment, so one of the ways to reduce environmental risks is to develop an effective waste management system to stop chaotic processes during disassembly activities. Destruction waste differs from construction and demolition waste by the presence of accompanying hazardous components, complicating the development of a waste management system. The main components of destruction waste should be used as secondary raw materials for construction, production of building materials and other purposes. Provided that appropriate physical-geographic, engineering-geological, hydrogeological, technical, and socio-economic conditions are available, it is advisable to create temporary waste storage sites, with their subsequent use as secondary raw materials in the post-war period for restoration of civil, industrial, and transport infrastructure in the regions of Ukraine.

A Systematic review of integrated management system frameworks: Dimensions and implication for sustainable management of construction and demolition waste

The literature has increasingly dealt with management systems, using Total Quality Management (TQM) and Integrated Management System (IMS) interchangeably. While several terminologies have been used in the literature to refer to these two, the degree of integration of the various components of the management systems varies widely between studies. Therefore, there is a high possibility that it will be difficult to find a general or appropriate model without disciplinary barriers. Therefore, this systematic literature review (SLR) provides a holistic overview assessment and guidance of key existing studies on management system frameworks, components, factors influencing the choice of IMS, and challenges. Given the lack of existing studies focusing on construction waste, particular attention is given to the construction industry. This SLR intends to: (1) identify IMS dimensions and how the concept relates to environmental and sustainability management; (2) discover IMS frameworks and factors affecting them. A typical systematic literature search method was used to analyze the articles available on SCOPUS, Web of Science, Science Direct and Google Scholar Host between 2010 and 2022, resulting in the selection of 85 theses. The results show the following: (1) Studies indicate different forms of IMS frameworks depending on their specific study area; (2) A variety of conditions and factors affect IMS implementation, including cost reduction, optimized resources, unification of internal audits; Increased staff training; (3) Several limitations were identified in the analyzed papers, such as: the alignment of sustainability practices with environmental laws. Consequently, there is a need for a more interdisciplinary IMS approach, a deeper analysis of the effectiveness of the IMS framework across industries and regions.

Temporal evolution and thematic shifts in sustainable construction and demolition waste management through building information modeling technologies: A text-mining analysis

Construction and demolition activities are significant contributors to waste generation worldwide. As population growth accelerates worldwide, the amount of construction and demolition waste (C&DW) will increase proportionally unless proactive measures are implemented. This study analyzes the evolving research landscape on utilizing Building Information Modeling (BIM) technologies to advance sustainable C&DW management practices. A comprehensive text-mining analysis is conducted on 493 scholarly publications covering evolutions from January 2009 to February 2024 using the PRISMA framework. The research objectives are: (i) to identify key themes in domain of BIM technology in C&DW management using VOSviewer, (ii) to map the temporal evolution of research focus using SciMAT, and (iii) to identify emerging thematic trends.Co-occurrence analysis reveals three major research themes: (i) the use of digital twins and prefabrication for waste reduction, (ii) integrating environmental impact assessments, and (iii) data-driven decision-making. Strategic diagrams produced by SciMAT software uncover shifting priorities over the study period, with “reuse and recycling” emerging as motor themes, and “Prefabrication” (CIT = 481), “Decision Making” (CIT = 66), “Material Passport” (CIT = 92), and “Digital Twin” (CIT = 44) emerging as high-centrality and transversal themes. Temporal evolution mapping unveiled progressive integration of BIM tools such as (i) digital twins (TLS = 34, OCC = 9) and (ii) prefabrication (TLS = 40, OCC = 14), presenting opportunities to optimize waste reduction. This study offers a robust overview of the field, aiming to inform a diverse audience, including researchers from various disciplines, policymakers and industry professionals interested in advancing sustainable practices in C&DW management through innovative digital solutions.

Improving the Decision-Making for Sustainable Demolition Waste Management by Combining a Building Information Modelling-Based Life Cycle Sustainability Assessment Framework and Hybrid Multi-Criteria Decision-Aiding Approach

Increasing efforts have been devoted to promoting sustainable demolition waste management (DWM) from a life cycle thinking perspective. To this end, facilitating sustainability-oriented decision-making for DWM planning requires a sustainability assessment framework for assessing the trade-offs among multifaceted criteria. This study develops a BIM-based DWM sustainability assessment approach to facilitate the life cycle sustainability assessment (LCSA) and decision-making by integrating LCSA-related properties and hybrid Multi-Criteria Decision-Aiding (MCDA) methods into a BIM environment using Dynamo visual scripting. A dynamic linkage is developed in the streamlined BIM-based LCSA process, where the enriched Industry Foundation Class (IFC) models are coupled with custom LCSA data templates to achieve seamless data exchange between the BIM platform and external LCA tools. Subsequently, hybrid MCDA methods convert the assessment results into DWM scenario ranking. A pilot study verifies the applicability of the BIM-based framework. The results unveil that the sustainability score ascended with the recycling rate. The optimal DWM alternative with the highest recycling rate yields the highest sustainability score at 91.63. Conversely, a DWM alternative reflecting the ‘status quo’ in China’s recycling industry has the lowest score at 8.37, significantly lower than the baseline scenario with a 50% recycling rate. It is worth noting that the ‘growth curve’ of the sustainability score continuously flattens as the target recycling rate escalates. The increment in recycling rate from the “Australian standard” scenario to the optimal scenario is 18.4%, whereas the sustainability score merely increases by 2.3%, implying that the former scenario arrived at an optimum point for maximising the cost-efficiency of DWM under the predefined settings.

Decision support model for selecting construction and demolition waste management alternatives: A life cycle-based approach

Construction and demolition waste (C&DW) represents a pressing concern within the European Union, underscoring the urgent need for effective waste management strategies. The selection of these solutions constitutes a complex task, entailing the identification of efficient C&DW management strategies that balance appropriate practices, regulatory compliance, resource conservation, economic feasibility, and environmental considerations. LCA is widely utilized to assess environmental impact, yet the economic aspect has not been adequately incorporated into the LCA process in the field of C&DW management. The life cycle costing (LCC) methodology has been tailored to assess economic performance in conjunction with LCA. The selection of an appropriate multi-criteria decision-making (MCDM) method is vital for the C&DW system. This study proposes a novel framework for C&DW management by integrating LCA and LCC outcomes into MCDM, using AHP for weight determination, and applying TOPSIS to identify the favorable alternative. Four waste management alternatives were examined in the Lombardy region of Italy, namely (i) landfill; (ii) recycling for concrete production and road construction, incineration with energy recovery; (iii) recycling for road construction; (iv) recycling for concrete production and road construction. We determine that, with the implementation of various scenarios, the most suitable scenario emerges to be recycled for concrete production and road construction, with a score of 0.711/1; recycling for road construction with final score 0.291/1, ranks second; recycling for concrete production and road construction, incineration with energy recovery scores 0.002/1, ranks third; and landfill (scores: 0/1) is the worst choice, signifying it has the highest environmental impacts and the least economic benefits. Lastly, recommendations were formulated to enhance the environmental performance of the system.

Sustainable composites with synergistic combinations of construction and demolition waste: Behavior of rubber, HDPE, PS, and brick after short-term water immersion

The growing concern for environmental sustainability and construction and demolition (C&D) waste management has led to innovative approaches to recycling and reusing these materials. This study presents the development of sustainable composites using a unique mix of C&D wastes: rubber, high-density polyethylene (HDPE), polystyrene (PS), and bricks. Mechanical tests were performed to determine their structural integrity and suitability for construction applications. The composites were further subjected to immersion in water to evaluate their resistance to environmental factors. In addition, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) analyses were performed to obtain information on the chemical and morphological properties of the composites. The synergy achieved by combining C&D waste materials such as rubber, HDPE, PS and bricks resulted in composites that exhibited outstanding mechanical properties. The samples with the composition rubber:HDPE:PS:brick = 15:40:40:5 immersed in water for 21 days presented the best mechanical resistance properties: Rc = 146.51 MPa, Ei = 36.05 kJ/m2, Rt = 11.2 MPa. The results demonstrated that the composites maintained their structural integrity and did not undergo significant degradation when exposed to moisture, highlighting their potential for use in wet or humid environments. FTIR analysis provided valuable information on the chemical composition of the composites. The interactions between the individual components led to the formation of new chemical bonds, strengthening the overall structure of the composite material. SEM images revealed a homogeneous distribution of the components in the composites, confirming their excellent compatibility. XRD analysis showed that the crystal structure of the composites was optimized for mechanical performance, further supporting their suitability for construction applications.

Challenges in the management of construction and demolition waste in Beira-Sofola

Challenges in the management of construction and demolition waste in Beira-Sofola

Examining the Drivers to Support Improved Construction and Demolition Waste Management for a Circular Economy: A Comprehensive Review Using a Systematic Approach

With the rapid pace of global urbanisation, construction demolition waste (CDW) constitutes roughly 36% of the total solid waste deposited in landfill sites worldwide, thereby posing a significant challenge to the sustainability of the construction industry. To address this issue, circular economy strategies are proposed as a solution. This paper systematically analyses 55 research articles published in leading peer-reviewed English-language scholarly journals over the past decade. It aims to identify and categorise drivers for enhanced CDW management by synthesising findings from previous research to support the principles of a circular economy. Utilising a PESTLE model for classification and analysis provides valuable insights into disparities and distinctions among categories, regions, and countries. The resulting analysis yields valuable insights into enablers and trends, with the aim of making a substantial contribution to mitigating the impact of construction activities and thus fostering the establishment of an efficient circular economy within the sector.

Optimal supply chain performance: risk aversion to green innovation

PurposeAlthough many countries are focusing on the management of construction and demolition waste (CDW) resource utilization, the effect of risk aversion of the green innovation-led enterprise on the performance of the CDW resource utilization supply chain is unclear when considering different green innovation contexts (green innovation led by the building materials remanufacturer or by the construction waste recycler). This study aims to investigate how the level of risk aversion of the green innovation-led enterprise affects CDW resource utilization under different green innovation contexts based on contingency theory.Design/methodology/approachUsing Stackelberg game theory, this study establishes a decision model consisting of a building materials remanufacturer, construction waste recycler and CDW production unit and investigates how the level of risk aversion of the green innovation-led enterprise under different green innovation contexts influences the performance level of the supply chain.FindingsThe conclusions are as follows. (1) For the green innovation-led enterprise, the risk-averse behaviour is always detrimental to his own profits. (2) For the follower, the profits of the construction waste recycler are negatively correlated with the level of risk aversion of the green innovation-led enterprise in the case of a small green innovation investment coefficient. If the green innovation investment coefficient is high, the opposite result is obtained. (3) When the green innovation investment coefficient is low, the total supply chain profits decrease as the level of risk aversion of the green innovation-led enterprise increases. When the green innovation investment coefficient is high, total supply chain profit shows an inverted U-shaped trend with respect to the degree of risk aversion of the green innovation-led enterprise.Originality/value(1) This study is the first to construct a green innovation context led by different enterprises in the CDW resource utilization supply chain, which provides a new perspective on green management and operation. (2) This study is the first to explore the operation mechanism of the CDW resource utilization supply chain based on contingency theory, which provides new evidence from the CDW resource utilization supply chain to prove contingency theory. At the same time, this study examines the interactive effects of the green innovation cost coefficient and the degree of risk aversion of green innovation-led enterprises on the performance of supply chain members, expanding the contingency theory research on contingencies affecting enterprise performance. (3) This study will guide members of the CDW resource utilization supply chain to rationally face risks and achieve optimal supply chain performance.

Consequential life cycle assessment of demolition waste management in Germany

ContextBulk mineral waste materials such as construction and demolition waste are Germany’s largest waste stream. Despite the availability of high-quality recycling pathways such as road base layers, waste concrete is predominantly recycled into lower-quality recycling pathways like earthworks or unbound road construction. This is due to low demand for recycled aggregates in road base layers and frost protection layers, especially in public procurement.PurposeThis study assesses the environmental consequences of increasing high-quality recycling of waste concrete in the near future to provide decision support for public procurement in Germany. The focus lies on climate change due to its importance for decision-makers. However, 17 other impact categories were assessed to avoid problem shifting.MethodsLife cycle assessment (LCA) is applied with background data from ecoinvent 3.9.1. Impact assessment was conducted at midpoint level using IPCC 2021 and ReCiPe Midpoint (H). Foreground data were taken from literature and expert interviews. In line with the goal of this LCA, a consequential modeling approach was followed to account for changes in the material flow system. Substitution creates a cascade effect previously omitted in consequential LCA studies, in which lower quality recycling materials replace higher quality recycling materials in their respective utilization pathways.Results and discussionIncreasing the high-quality recycling of waste concrete into road base layers causes a reduction in environmental impacts for all 18 impact categories, as it replaces natural aggregate and avoids backfilling of mixed mineral waste and excavated earth through substitution effects. Transport distances and ferrous metal recovery were identified as hot spots. Sensitivity analyses show that only transport is a significant issue.ConclusionIncreasing the high-quality recycling of waste concrete in Germany is recommended in terms of environmental impacts. Lower-quality recycling is environmentally feasible only in cases where the avoided transport distances for natural aggregates and backfilling are significantly lower than the additional transport distances for high-quality recycling.

Development of a 3D Digital Model of End-of-Service-Life Buildings for Improved Demolition Waste Management through Automated Demolition Waste Audit

This paper presents the development of a 3D digital model of end-of-service-life buildings to facilitate a step change in preparation of pre-demolition protocols that can eliminate problems of inadequate documentation and extensive time spent in preparing pre-demolition audits. The 3D digital model consists of the following four main components: (i) digitization of paper-based drawings and their conversion to CAD; (ii) automated generation of a 3D digital model from CAD; (iii) corrections to the 3D digital model to account for changes in the lifetime of a building; (iv) a sub-model for performing pre-demolition audit. This paper proposes the innovative approaches of incorporating a minimal amount of human intervention to overcome numerous difficulties in automated drawing analysis, application of augmented reality (AR) in corrections to the 3D digital model, and data compatibility for pre-demolition audit. These processes are demonstrated using one building as case study. Using the digital model, a pre-demolition audit can be prepared in minutes rather than the many days required in current practice without a digital model. The accurate quantification of the quantities and locations of different demolition waste materials and products in buildings to be demolished will enable a systematic and quantitative evaluation of potentials of material and product reuse and eliminate contamination of different demolition waste streams (which may contain hazardous waste), which is the main cause of environmental degradation and downcycling of demolition waste materials.