Advances in Circular Valorization of Construction and Demolition Waste (CDW) Toward Low-Carbon and Resilient Construction: A Comprehensive Review

Abstract

Civil engineering faces the dual challenge of addressing climate change and managing construction and demolition waste (CDW). While existing analyses often focus solely on the mechanical characteristics of recycled materials, there is a significant gap in research on integrating these technical advancements with climate-resilient infrastructure and public policies that encourage circularity. This article offers a detailed review of the technical possibilities for materials derived from CDW, shifting the focus from “low-value recycling” to higher value-added uses. We analyze progress in this area over the past decade (2015–2025), specifically exploring the role of Building Information Modeling (BIM), Artificial Intelligence (AI), and advanced pretreatment processes (such as carbonation and alkaline activation) in improving material properties. A unique contribution of this work is the creation of a conceptual framework connecting materials science to global sustainability indicators and urban resilience strategies. Our findings show that, while technical feasibility is well established, the transition to a circular economy is hampered by the absence of standardized environmental metrics and effective public policies. This review summarizes these interdisciplinary trajectories and presents a plan for engineers and policymakers to transform construction and demolition waste (CDW) from a problem into a strategic resource for climate-adaptable urban development.

1. Introduction

Global temperatures are expected to exceed the 1.5 °C warming ceiling in the coming decades, rising as much as 4 °C by the end of the century if current trends continue [1]. The construction industry is largely responsible for this situation, accounting for approximately 40% of global carbon emissions annually. This is mainly due to the production of energy-intensive materials such as cement, steel, and asphalt, and linear production models that generate substantial construction and demolition waste [2].

By contrast, civil infrastructure is more exposed to climate stressors, including high temperatures, rising sea levels, heavy rainfall, and drought. These events pose risks, including structural damage, operational interruptions, and, in some cases, catastrophic failures [3]. The destructive impact of these phenomena is evident in the recent floods in Brazil, Spain, and Nepal (

Table 1. Recurring climate events and infrastructure impacts.

Country	Event Description	Human Impact	Infrastructure Impact	Source
Brazil	Floods in Rio Grande do Sul	173 deaths, hundreds of injuries, mass displacement	Severe damage to roads and bridges	[4]
Spain	Historic flood in Valencia	Over 200 deaths, service disruption for thousands	Urban drainage and power grid failures	[6]
Nepal	Nationwide flooding	2.59 million people affected	Failures across all infrastructure sectors	[5]

), which caused severe damage to bridges and drainage systems in cities [4,5,6]. Extreme weather conditions intensify material degradation, such as metal corrosion and cracks on concrete surfaces, compromising infrastructure durability and increasing maintenance costs [7,8]. To adapt, civil engineering needs to invest in resilient projects and promote a comprehensive transformation of the sector [9].

Extreme weather conditions accelerate material deterioration, such as metal oxidation and surface cracks in concrete, reducing asset durability and increasing maintenance costs [9,10]. For example, road modifications due to climate change could increase annual maintenance costs by hundreds of millions of dollars globally by 2050 [7,8]. To adapt, civil engineering must invest in robust design and a broad transformation of the sector [9]. A summary of key climate threats and their impacts on infrastructure is presented in

Table 2. Key climate threats and impacts on civil infrastructure.

Climate Threat	Event Description
Extreme temperatures [10,11]	Accelerated material deterioration, thermal expansion, and increased energy demand
Heavy rainfall/floods [4,5]	Erosion, foundation instability, bridge and road damage
Droughts [12]	Soil shrinkage, cracking of pavements, and water supply system failures
Sea level rise [8]	Coastal infrastructure flooding, corrosion of materials
Freeze–thaw cycles [13]	Surface cracking, accelerated concrete degradation

.

These extreme weather events are becoming commonplace and cannot be seen as isolated cases, but rather as a systemic transformation that surpasses the predictive capacity of conventional engineering techniques. This reveals a significant disconnect despite the increased frequency and severity of these phenomena; climate models and design standards guiding infrastructure construction are still based on immutable historical data. These outdated models fail to account for contemporary climate change, which does not follow linear patterns, resulting in inadequate assessments of structural risks [8]. Therefore, civil engineering needs to adopt a two-pronged strategy: modernizing predictive models to reflect current environmental challenges while simultaneously incorporating materials that reduce carbon emissions in the sector.

There is a strong correlation between the valorization of CDW in the construction supply chain and climate change mitigation strategies. Reusing this waste rather than disposing of it in landfills reduces energy demand for new mining operations and preserves natural carbon sinks. As Szalay [14] mentioned, it is adopting parametric models to assess environmental impact is fundamental to establishing reference values for embodied carbon in buildings. Therefore, the circularity of CDW, in addition to providing the necessary materials for resilient adaptation, directly reduces the sector’s embodied carbon (extraction, manufacturing, and transportation), thereby mitigating its contribution to global warming. Overcoming the barriers to sustainable construction, Hakkinen and Belloni [15] demonstrate that it involves separating materials management from resource consumption, thereby ensuring a low-carbon life cycle.

Despite the progress, a significant gap in research remains: many studies to date treat the valuation of CDW as an isolated problem confined to the laboratory, with no connection to broader policies on climate resilience in cities and digital transformation. This review seeks to fill this crucial gap by presenting a multidimensional synthesis that combines innovation in materials, digital monitoring (BIM/AI), and life-cycle assessment (LCA) [16,17].

The central purpose of this article is to move beyond a simple descriptive analysis of recycled resources and to offer a strategic guide to “high-value circularity.” By connecting technical feasibility, including soil stabilization and advanced concrete treatment methods, with management and digital technologies, this research makes an innovative contribution by considering CDW not only as recycled byproducts but also as essential assets for creating climate-resilient, data-driven infrastructure.

2. Technical Opportunities in CDW-Based Materials

The construction industry is transforming to become more efficient in materials use and to adopt circularity, driven by digital optimization through Building Information Modeling (BIM) and the incorporation of CDW into material cycles [16,17,18]. The schematic flow is shown in Figure 1.

Environmental Product Declarations (EPDs) are used to accurately assess the life-cycle effects of materials [19,20]. Innovation in materials and the practical implementation of CDW represent the main paths for civil engineering in combating climate change. Transforming waste into high-performance materials constitutes an effective approach to minimizing environmental impacts and ensuring the durability of buildings. These material-based opportunities, rather than generic policy targets, represent the most efficient way for engineering to meet current climate demands [21]. Furthermore, the transition to a circular model requires technological advances that enable the large-scale incorporation of recycled aggregates into structural concrete, thereby significantly reducing the sector’s carbon footprint, as noted by Tam et al. [22].

2.1. Development of Climate-Resilient Infrastructure

Efficient urban planning must adapt to the increase in severe weather events to ensure safety and sustainability. This requires implementing approaches that utilize combined natural and alternative solutions from the outset of the project [11,23]. Developed construction techniques and materials are essential to cope with flooding, intense heat, and storms [4,24]. Some specific adaptations include elevated roads in flood-prone regions [25], moisture- and corrosion-resistant materials in coastal areas, and flexible constructions that can be adjusted to future climate changes [26].

Table 3. Climate-resilient infrastructure strategies.

Strategy	Primary Benefit	Source
Elevated roads in flood zones	Reduces vulnerability to floods	[25]
Nature-based solutions	Green roofs, permeable pavements	[23]
Robust materials	Flood- and corrosion-resistant	[11]
Digital simulations	Predict vulnerabilities using climate data	[27]

summarizes strategies for enhancing infrastructure resilience to climate-related risks.

Furthermore, combining virtual simulations with climate information enables engineering professionals to identify vulnerabilities and enhance building durability [27]. It is essential to balance resilience with reduced emissions; adaptation and mitigation strategies complement each other to achieve carbon neutrality throughout an asset’s life-cycle [28].

2.2. Innovative Technologies

Digital transformation in the construction industry is vital to mitigating the impacts of climate change. New technologies such as IoT, Artificial Intelligence, Building Information Modeling (BIM), and Digital Twins, among others, enable waste reduction and more accurate information integration. Innovative technologies play a crucial role in addressing climate change. Optimizing projects to reduce waste through digitalization and advanced modeling, and applying techniques such as BIM [29].

Beyond waste reduction, technological innovations enhance energy efficiency and support long-term management. Gao, Wang, and Xu [27] suggest using digital twins, the Internet of Things (IoT), 3D printing, and robotics to improve energy efficiency. To predict climate impacts and enhance infrastructure management, Papadopoulos & Balta [30] suggest using artificial intelligence and big data. More advanced studies propose a deep sorting process that leverages artificial intelligence and robotics to improve CDW quality. Chen et al. [31] developed a prototype mobile robot for recycling work on construction sites, equipped with an advanced real-time 3D location and navigation system that achieves high efficiency and accuracy.

Wang, Li, and Yang et al. [32] developed advanced robotic technology that employs two residue recognition algorithms. The authors demonstrate that these algorithms, combined with technologies such as Simultaneous Location and Mapping (SLAM) and an instance segmentation method, can more efficiently and quickly identify the CDW. The authors implemented a CDW database to train a computer vision model. This enhanced recognition and sorting accuracy is crucial for producing purer input streams. As a direct consequence of this effective separation, high-quality Recycled Coarse Aggregate (RCA), Recycled Fine Aggregate (RFA), and Recycled Cementitious Powder (RCP) are obtained.

Machine learning analysis is also an alternative approach to enhance infrastructure management, enabling the prediction of potential failures and the optimization of resource utilization [27,30]. For the construction industry to undergo a significant transformation, new construction technologies must be combined with rigorous environmental metrics. To achieve this, Civil Engineering must enable sustainable decisions by incorporating diverse innovations into a data ecosystem and adopting digital tools. This discussion of robotics focuses on its application to the separation and sorting of end-of-life (EoL) waste, which aligns with the scope of this review.

2.3. Policy and Planning

Innovative techniques such as carbon capture, utilization, and storage (CCUS), including carbon dioxide storage in underground geological formations, the use of cementitious materials as carbon sinks throughout their life cycle, and the reuse of carbon dioxide to produce carbonate material [33,34].

While innovations in materials and technologies provide essential tools for Civil Engineering to mitigate carbon footprints and promote CDW circularity, the construction sector’s inertia and market barriers require strategically targeted policy interventions, including metric standardization (e.g., LCA) and a focus on Environmental Product Declarations (EPDs) for sustainability. The effective adoption of these solutions depends directly on a robust Policy and Planning framework [35]. In this context, Civil Engineering plays a crucial role, not only in implementing technical solutions but also in providing data for decision-making on sustainability and effective policymaking. This contribution is evident in the direct link between materials science, the construction process, and climate objectives [19]. In public policies for carbon mitigation, Carbon Dioxide Removal (CDR) is central to achieving these goals, and its environmental impacts are often analyzed using LCA to evaluate synergies with circularity [36]. Within this area, three key approaches are defined: CCUS, which focuses on capturing CO₂ directly from primary emitters, such as cement and power plants, and permanently storing it in geological formations. CCUS includes routes for converting captured CO₂ into value-added products such as synthetic fuels, chemicals, and construction materials. Finally, Bioenergy with Carbon Capture and Storage (BECCS) is classified as a negative-emission technology, combining CO₂ capture from biomass burning with geological storage, which results in the net removal of atmospheric carbon [37].

One of the key strategic pillars for addressing climate change through civil engineering is the development of effective policies and plans. To encourage the implementation of sustainable, resilient practices, it is essential to integrate climate objectives into civil engineering. To achieve this, public policies and strategic planning are vital. Establishing regulations, standards, incentive mechanisms, and certifications provides a framework for achieving these objectives. Civil engineers can be crucial in formulating policies and regulations that promote the capacity to quickly resist and recover from the adverse effects of climate change (climate-resilient development) and in designing systems that ensure economic, social, and environmental sustainability throughout the life cycle of infrastructure (sustainable infrastructure) [38]. Mas-Coma et al. [24] discuss the need for carbon footprint reporting in infrastructure projects, arguing that it should be mandatory and that public policies should be more supervisory than solely incentivizing.

To achieve effective adaptation through strategic development, Mosisa et al. [23] emphasize integrating public policies with scientific evidence. Recent findings by Amran et al. [10], Franco et al. [39], and Andric, Koc, and Al-Ghamdi [3] suggest that technological innovations require tax incentives and subsidies, and mandatory efficiency standards. Papadopoulos and Balta [30] suggest developing technical standards aligned with sustainability, driven by the sector’s digitalization. According to the OECD [11], collaboration between the government and the private sector would facilitate the exchange of data and best practices through intersectoral platforms.

Implementing requirements such as climate risk assessments for the approval of large projects would be a good practice, as integrating climate goals into development plans is essential [11,39]. Creating environmental performance indicators for infrastructure projects and implementing audits and monitoring throughout the project life cycle are also sustainable and resilient practices [36]. The lack of international harmonization in methodologies, such as LCA, makes it difficult to measure real progress in reducing greenhouse gas (GHG) emissions.

Long-term climate forecasts should be incorporated into infrastructure planning; however, aligning infrastructure with global emissions-reduction goals requires integration among governments, the private sector, and civil society. Mandatory regulations, international standardization of environmental metrics, auditable emissions reporting, and voluntary incentives are crucial to combating climate change.

2.4. Sustainable Materials and Circular Economy Practices

The construction industry has made reducing its carbon footprint a key priority. To this end, new materials and construction methods have become the focus of extensive scientific research. Options such as low-carbon cements, modular solutions incorporating industrial waste, modular prefabrication, and alkali-activated concretes are among the strategies currently being investigated by the sector.

Among the most promising strategies to reduce natural resource consumption and CO₂ emissions is the circular economy [36], which prioritizes reuse, recycling, and waste reduction across the project lifecycle. The industry can shift toward more sustainable materials and construction practices that reduce greenhouse gas emissions and minimize environmental impact [40]. This includes the use of recycled materials, reduced cement consumption, and the adoption of energy-efficient construction techniques [35]. It also involves replacing cement with low-impact materials, such as industrial waste and geopolymers (fly ash, blast-furnace slag, natural and artificial pozzolans), which significantly reduce the carbon footprint while improving durability and chemical resistance.

Extensive research has examined various types of waste, including CDW. This material is produced in large quantities worldwide and typically has a low reuse rate, making it suitable for a wide range of applications. The following sections will elaborate on aspects of its use that may contribute to climate change mitigation. The incorporation of new materials as partial or total substitutes for traditional ones has been studied for decades. However, adopting more holistic perspectives has proven particularly challenging for the construction sector. This is exemplified by the implementation of a circular economy approach, which aims to reduce consumption of natural resources, increase durability, and lower emissions throughout a building’s life cycle. Through this transformative strategy, the construction industry shifts from being a primary source of environmental impact to a key partner in addressing climate change.

Following this tendency, Munaro Tavares [41] addresses deconstruction and adaptability. This approach centers on the Design for Adaptivity and Disassembly (DfAD) methodology, which comprises the Design for Deconstruction (DfD) and Design for Adaptability (DfA) methods. The DfD method involves planning and designing a building with a structure that facilitates dismantling at the end of its service life, thereby simplifying reuse [41,42]. The DfA method, by contrast, aims to ensure that buildings can be modified and adapted over time, thereby avoiding premature demolition and extending their service life [43]. Both DfD and DfA are key instruments for carbon mitigation and for implementing circularity principles. Cai and Waldmann [42] divide structures in their final phase of use into two categories: engineered structures (DfD) and non-engineered structures. In the designed structure, the old structures enter the “smart demolition techniques” process, which consists of a circular process of Deconstruction & Disassembly, Management of reusable components, Transport and connection design, Reconstruction of components, Reassembly and reconstruction, and return to Deconstruction & Disassembly. The non-designed structure process: old structures are recycled or deposited in landfills.

2.5. Overall Considerations on Sustainable Infrastructure and Innovation

Based on the topics discussed, it is evident that fostering sustainable, resilient infrastructure will require the construction sector to integrate new technologies, engage effectively with public policy, and adopt innovative construction practices. These actions will enable civil engineering to play a central role in combating climate change. In this context, mitigating climate change is a very important factor; however, valuing CDW is equally vital for preserving natural resources and reducing waste. Adopting a permanent circular economy remains a historical necessity and a professional responsibility, even when the energy required to process recycled materials challenges the economic benefits of using natural resources. Thus, engineering transcends its traditional technical scope. It has emerged as a leading discipline for addressing climate challenges through innovation and sustainability, integrating multidisciplinary fields spanning scientific, technological, political, and social dimensions.

3. The Role of Construction and CDW in Climate Change Mitigation

One strategy in international policy to transform waste streams into high-value resources is to maximize the circular recovery of CDW. To measure circularity’s effectiveness, a quantitative, integrated evaluation framework is needed. Therefore, to improve waste efficiency, it is essential to reduce the environmental impacts of transport and maximize the performance of treatment methods. Accordingly, the three dimensions of sustainability (Environmental, Economic, and Social) were established as the analytical pillars of this study, utilizing the LCA-based Sustainability Index for Construction Waste (CWLSI) [44]. This index serves as a fundamental basis for our assessment, offering an organized overview of how each valuation approach contributes to the decarbonization of sectors across its sub-indices.

CDW is viewed as both an environmental challenge and a technical resource for civil engineers to mitigate climate change. Thus, this waste accounts for a significant share of global waste, and its sustainable management is essential to enhance civil engineering resilience, align with the Sustainable Development Goals, and support carbon neutrality [45]. For effective waste management, quantitative surveys and sustainability assessments using composite indicators (including objectives, evaluation criteria, indices, and performance parameters) are indispensable. An integrated, lifecycle-based framework for CDW management was proposed by Yeheyis et al. [44], divided into three key phases:

• Pre-construction phase: Focused on reducing waste through the implementation of policies, the use of technologies, such as BIM, and the optimization of resources, still in the project.
• Construction and renovation phase: It aims to minimize waste generation through efficient management of materials and on-site sorting.
• Demolition phase: Utilizes selective deconstruction techniques to maximize the recovery of recyclable and reusable materials. The non-recyclable fractions are directed to composting, incineration, or landfill.

At the heart of this framework is the Construction Waste Life Cycle-Based Sustainability Index (CWLSI), established as a decision-support tool. The authors select performance indicators across the environmental, economic, and social dimensions, which are normalized, weighted, and aggregated to calculate specific sub-indices, which are then combined to derive the final CWLSI. In the present study, the fundamentals of the CWLSI were applied to organize the available literature, ensuring that the evaluation of each technology or policy goes beyond technical feasibility and considers its broader socioeconomic and environmental effects. Yeheyis et al. [44] concluded that the LCA-based Sustainability Index for construction waste can be a helpful tool for decision-making regarding material selection, sorting, recycling, reuse, and treatment and disposal options for construction and demolition waste. Recycling and reusing this waste offer environmental, economic, and social benefits, as outlined below.

3.1. Environmental Benefits

Reusing waste reduces the amount sent to landfills, preserves soil, and reduces land-use impacts, thereby extending the operational capacity of existing landfills. Using CDW reduces natural resource consumption, thereby contributing to ecosystem conservation [45]. Purchase et al. [46] conducted a comparative study between the linear economy model (in which construction materials, at the end of their useful life, are destined for landfills or incineration) and the circular economy model (which keeps materials in use for longer). They found that circularity in the CDW sector reduces natural resource consumption (Figure 2a,b).

Tanthanawiwat et al. [47] conducted a comparative study of conventional landfill management and a 100% recycling scenario to assess environmental impacts. For concrete constructions, the reduction in natural resource scarcity would be approximately 24%. For wooden structures, the reduction would be around 65%. Based on these results, the authors found that environmental credits would be generated, yielding net benefits from replacing materials derived from natural resources with recycled materials. A study by Barros Martins et al. [48] in the municipality of São José dos Campos, São Paulo, showed that sending all waste to landfills resulted in approximately 26,618 tCO₂eq of emissions and a consumption of 48.086 million BTU in 2021. A simulation using the WARM model (Waste Reduction Model, developed by the USEPA) was based on waste generation in this municipality, which amounts to approximately 205.6 thousand tons of municipal solid waste and 435.5 thousand tons of CDW. The authors verified reductions of 10,836 tCO₂-eq in emissions and approximately 978,842 million BTU in energy savings. The authors demonstrate that these benefits result from the recycling and reuse of CDW as an aggregate in civil construction.

To increase resource efficiency, Gálvez-Martos et al. [49] suggest reducing transport-related impacts and maximizing the environmental performance of waste treatment methods. To improve the final quality of recycled aggregate, the authors suggest optimizing Best Management Practices (BMPs), which include minimizing transportation impacts and maximizing the reuse and recycling of secondary materials. However, quantifying the demonstrated environmental benefits is not always straightforward or linear. LCA results for recycled materials are highly dependent on the system boundaries and the allocation method used (or “cut-off” rule) [50]. For example, a 100:0 cut-off rule—often applied in standardized product category rules such as EN 15804—assigns all benefits of resource substitution to the product containing the recycled material, effectively treating the recycled input as “burden-free” [51]. Conversely, different allocation methods, such as 0:100, would assign all burdens from the recycling process to the user of the recycled material, potentially canceling or even reversing the perceived benefit. This crucial methodological dependence shows that the environmental benefit of recycling is, to some extent, an accounting outcome.

3.2. Economic Benefits

While the environmental advantages of CDW recycling are evident, it also has direct economic implications, as explored below. Rohani et al. [52] examined two scenarios: partial recovery of materials and waste reduction and reuse. The authors observed that both scenarios yielded economic and social gains, resulting in net benefits of approximately US$6.97 million in the first scenario and US$14.46 million in the second. These benefits included job creation, reduced gas emissions, and the economic use of reused materials. Although entrepreneurs were near the financial break-even point (a limitation on direct profitability), the circular economy in CDW, according to the authors, yields substantial collective and environmental benefits.

Caro et al. [21] analyzed two types of recycling: conventional recycling, which uses current techniques to produce recycled aggregate (such as concrete, bricks, ceramics, and glass), and advanced recycling, which produces supplementary materials from construction waste. The authors compared average treatment costs. The average cost of conventional recycling is approximately 4.6 ± 1.1 EUR/t, whereas that of advanced recycling is 25 ± 7 EUR/t. The authors noted that advanced recycling is much more expensive than conventional recycling. However, in terms of global economic benefits by mitigating economic and climate impacts, advanced recycling reduces an average of 264 ± 51 kg CO₂-eq per ton of CDW. By comparison, conventional recycling reduces 181 ± 28 kg CO₂-eq per ton of waste.

A study in New Zealand by Purchase et al. [46] proposed introducing a landfill disposal fee to encourage recycling and reuse of waste, along with a severe fine for illegal disposal. Together, these measures formed a conceptual model of the waste chain that evaluated the environmental and climatic effects of varying the chain’s components. For recycled materials to be cost-competitive, economic measures such as landfill taxes or fees are important. To this end, Tošić et al. [53] used multi-criteria optimization to assess concrete with recycled aggregates, identifying landfill taxes as viable measures to achieve cost parity. The authors noted that as rates increased, so did the economic and social benefits. They concluded that, for waste minimization to be economically viable, the fee should exceed a threshold to cover costs. This practice would significantly reduce waste sent to landfills, decrease gas emissions, and save energy and natural resources.

Yuan et al. [54] included 8 variables (factors) in the conceptual model of the construction and demolition waste (CDW) chain that allow for the representation of the interactions of the key factors, which are as follows:

(1)

Environmental awareness: Increasing through strengthening regulations and raising awareness regarding the reduction in CDW.

(2)

Waste collection: Reduces illegal disposal and is directly related to incentives at different stages of CDW management.

(3)

Illegal disposal: It may incur environmental costs to the population.

(4)

Waste sorting: The percentage of sorting is directly linked to the incentive in the management of CDW.

(5)

Recycling and reuse: Two variables are needed to form the basis for calculating the benefits gained from managing CDW.

(6)

Regulation: Directly impacts CDW management, as strict regulation can result in less illegal disposal.

(7)

Total cost of waste management: This cost includes the environmental cost resulting from illegal disposal.

(8)

Total benefits of waste management: These include savings in disposal costs, savings in transportation, cost savings in the purchase of materials, and revenues from the sale of waste materials.

After the author introduced the main factors into the model, a diagram was developed to simulate the practice of CDW management on a computer.

For recycled aggregate to be cost-competitive, landfill fees or fines are essential [46]. In Europe, these cost-effective measures are sufficient to boost recycling and reuse, leading some member states to achieve diversion rates of more than 70% of CDW from landfill disposal [49]. However, the transition from the economic circularity model in the waste sector is not without risks and financial barriers. Immediate economic viability is constrained by the substantial upfront costs of advanced sorting and processing infrastructure. In addition, RA prices are more volatile than those of natural aggregates. The lack of targeted investment strategies and the risk of technological obsolescence in recycling equipment represent significant barriers to large-scale adoption, particularly for small and medium-sized enterprises [21]. A unified assessment framework for key strategies was applied in this review, comprising a descriptive analysis of CDW valuation, with the aim of evaluating the performance of recycled materials and digital technologies across three fundamental pillars: Technical feasibility, economic viability, and environmental impact. This framework identifies the main scientific bottlenecks hindering the transition to a large-scale circular economy in the context of climate change.

Table 4. Unified evaluation of CDW valorization based on the proposed sustainability framework.

Case Study/Material	E.I.	E.V.	T.F.	Key Scientific Issue	Main References
Recycled Concrete Aggregates (RCAs)	H(+)	M	H	Quality variability and carbonation	[53,55,56]
Recycled Glass in concrete	M	L	M	Alkali-silica reaction (ASR)	[57,58,59]
Ceramic Waste (Bricks/Tiles)	M	M	H	Pozzolanic activity optimization	[55,60,61]
BIM-Integrated Management	H	L (Initial)	M	Data interoperability and sensors	[18,62,63]
Design for Disassembly (DfAD)	VH	L	M	Lack of standardized codes	[41,64]

E.I. = Environmental Impact; E.V. = Economic Viability; T.F. = Technical Feasibility; H = High; M = Medium; L = Low; VH = Very High.

highlights the trade-offs between technical maturity and market scalability.

3.3. Social Benefits

CDW management indirectly contributes to improving socioeconomic and health conditions. Aspects associated with CDW recycling are presented in

Table 5. Aspects associated with CDW recycling and social benefits.

Social Impact	Description	Source
Job Generation	Direct jobs in sorting, transporting, and processing CDW	[62]
Inclusion of Cooperatives	Insertion of waste pickers and cooperatives in the construction value cycle	[49]
Professional Training	Technical training programs for local labor in reuse techniques	[57]
Improvement of Urban Health and Health	Reducing pollution and disease vectors with less waste in dumps and burnings	[63]
Reduction in Social Vulnerability	Infrastructure projects with CDW reuse in underserved urban areas	[65]

.

The benefits of CDW management extend beyond environmental and economic improvements, as waste management creates concrete opportunities to include marginalized populations through job creation. It consequently directly affects long-term public health and education, stimulates regional development, and promotes social equity [49,66]. Circular-economy initiatives involving waste in developing countries integrate workers into cooperatives for collection, sorting, processing, and distribution, thereby providing income, access to social protections, and safer working conditions. This social benefit aligns with the principles of the Circular Economy, which aim to create new value chains [62]. Circular-economy initiatives involving waste in developing countries integrate workers into cooperatives for collection, sorting, processing, and distribution, thereby providing income, access to social protections, and safer working conditions. This social benefit aligns with the principles of the Circular Economy, which aim to create new value chains [62].

Training programs in low-income communities enhance technical recycling skills and support community projects that promote education for more sustainable construction focused on reusing CDW materials. These programs promote local empowerment and transform passive beneficiaries into active participants [57]. Gálvez-Martos et al. [49] identify a shortage of skilled labor and communication difficulties as the primary causes of inefficiency and excess waste on European construction sites, and emphasize that addressing these gaps is vital. In developing countries, illegal disposal of CDW remains common, and marginalized people live near landfills, exposed to hazardous materials, dust, and toxins. Proper management of CDW reduces reliance on landfills and, consequently, improves health and well-being for vulnerable communities [63].

Reducing reliance on sanitary landfills would increase soil fertility and improve conditions for constructing new housing, thereby providing a social benefit. Reusing waste that would otherwise be sent to landfills can help reduce soil contamination from toxic materials and unpleasant odors. Recent findings by Marinkovic et al. [66] suggest that numerous studies have thoroughly evaluated the environmental and economic benefits. However, the methodologies used in these analyses are inefficient for investigating social benefits. The authors argue that social indicators are subjective and, therefore, difficult to quantify due to the lack of large-scale data. Qualitative evaluation is more commonly used than quantitative evaluation in social benefit analyses. However, social inclusion through recycling cooperatives is evident. The adoption of new construction methods supports the technical training program, thereby benefiting peripheral communities [65].

3.4. Overall Considerations on Technical Trade-Offs and Circularity

According to this study’s findings, CDW management not only reduces greenhouse gas emissions and conserves natural resources but also delivers economic and social benefits. However, achieving these benefits is not automatic or trivial; it requires careful technical and political consideration.

From a technical standpoint, caution is needed regarding circularity and rapid decarbonization. CDW recycling can generate emissions from transport, shredding, and processing, and it can also consume significant energy. Under certain LCA limits, these factors can negate the benefits of reducing virgin raw material production. Multi-criteria decision-making is essential for finding the optimal balance among technical performance, cost, and environmental impact [53].

In addition, two critical pillars remain in this field. One gap is the rebound effect, which arises from the increased availability of materials from efficient recycling, potentially leading to higher consumption and negating the initial gains in resource conservation. Another research gap is the development of robust, large-scale quantitative methodologies to assess social benefits [36]. From this perspective, CDW is considered both a source of reusable materials and a precious resource. Furthermore, with appropriate management, the construction sector can adopt more circular, sustainable construction models, thereby mitigating climate change. To advance in this field, future studies should focus on standardized, harmonized LCA methodologies that clearly address allocation issues and develop quantifiable metrics for the essential social dimensions of circularity.

4. Circular Valorization and Climate Mitigation Through CDW Applications

Given the multiple options for using CDW, the examples presented in this section have been carefully selected to highlight the technical feasibility and the high value of recycled aggregates in civil construction. This section, which builds on optimizing the use of CDW as a significant resource and on exploring the environmental, economic, and social challenges outlined in Section 3, focuses on applications that extend beyond simple disposal, including concrete, structural components, and specific road pavements, demonstrating the sector’s potential to significantly reduce carbon emissions and enhance resource circularity.

Scientific research on the circular valorization of CDW has gained significant relevance, with numerous studies evaluating its use as an aggregate in concrete, mortar, and supplementary materials published in journals, books, and symposium proceedings. Many of these studies highlight the economic, social, and environmental benefits that contribute to environmental preservation, as presented in Section 3.

High-performance applications significantly reduce the embodied energy in new buildings and promote circularity. Such applications include, for example, the use of recycled powder as a partial replacement for cement, which contributes to the sector’s decarbonization, as discussed by Xiao et al. [67]. In parallel, the practical implementation of CDW in civil construction should be evaluated for its capacity to foster circular value creation and contribute to carbon sequestration, as highlighted by Silva et al. [68]. In this sense, the cases presented in this section demonstrate a technological transition in which CDW ceases to be treated as waste and becomes a strategic resource for mitigating and adapting to climate change.

4.1. Scope and Literature Selection

The database used for the systematic literature search was Scopus, and the most relevant studies on the circular valorization of CDW were considered. The decade from 2015 to 2025 was also considered because it coincides with the Paris Climate Agreement and the Sustainable Development Goals (SDGs), which scientifically justifies the time frame. The terms used in the search for Titles, Abstracts, and Keywords were “recycled aggregate,” “CDW,” and “CD&W.” This initial search yielded more than 13,000 documents. To ensure the systematicity and quality of the review, the following inclusion criteria were considered, resulting in 8906 documents: (i) articles from peer-reviewed journals; (ii) document language in English; (iii) relevance to the intersection between circular economy, climate change, and civil engineering. Exclusion criteria included conference proceedings, editorials, studies focusing exclusively on waste management without relation to the circular economy or environmental impact, and book chapters. After screening, we selected the most representative studies for full-text analysis and inclusion in this review.

An analysis of 8906 documents from the Scopus database (2015–2025) reveals a significant paradigm shift in research on CDW. In the last decade, the strategic focus has transitioned to sustainability and climate resilience (Figure 3a,b), overcoming the approach limited to the physical and mechanical properties of recycled aggregates. This evolution is reflected in the growing prominence of sub-areas such as Environmental Sciences and Energy (Figure 4).

Studies focused on mitigating climate impacts are led by China, followed by significant contributions from India and the United States. Additionally, countries such as Portugal, Brazil, and Germany have directed efforts towards aligning the valorization of CDW with urban resilience [69]. This trend indicates that technical performance has ceased to be an isolated objective and has become a fundamental component of the circular economy and low-carbon agenda.

4.2. Timeline Between 2015 and 2025

The purely technical approach to concrete with CDW, which was pursued in the previous decade, remains important; however, the search for low-carbon solutions and the mitigation of construction’s environmental impacts are now the central focus. Scientific production focused on the environmental, social, and economic benefits of CDW comprises 78.5% of articles, 17% of conference papers, and 4.4% of book chapters [69], highlighting the high level of rigor and advancement of knowledge in this field. The timeline will be presented below in condensed form, outlining each phase of the research on CDW related to sustainability and climate resilience in civil construction (

Table 6. Timeline between 2015 and 2025: CDW use in civil engineering, sustainability, and resilience to climate change.

Initial Technical Focus	Digital Integration and Focus on Infrastructure Resilience	Technological Consolidation and Resilience
2015–2017: Technical studies on the physical and mechanical properties of concrete and mortars using CDW as both coarse and fine aggregate. Analyses of the contribution of CDW use in reducing the effect of greenhouse emissions [17]. 2018–2019: During this period, there was increased attention to the circular economy, with several practical applications utilizing CDW as an aggregate. Studies on carbonation in recycled concretes were intensified. LCA and CO2 footprint were also considered in this period, driven by global climate treaties.	As a result of climate change, articles on the resilience of civil engineering have gained greater emphasis. The search for integrated digital tools to optimize large-scale projects and improve CDW quality was observed during this period. The use of BIM and GIS aims to optimize, track, and qualify the waste stream [27].	Embedded technologies applied for the optimization of waste streams and traceability, to predict mechanical properties in concretes with CDW, to enhance performance through tests with hybrid mixtures (CDW +fly ash, slag, silica fume). CDW treatments with accelerated carbonation to improve the mechanical properties of recycled concretes were also investigated [70].

).

A literature review indicates that the integration of processing technologies and new methods for analyzing and treating CDW was consolidated in 2024, a year marked by significant growth. This reflects the civil construction industry’s strong commitment to more sustainable, circular construction. The technological advances presented in the articles, along with proposals for infrastructure improvements and waste reuse, are listed below.

4.3. Aggregates in Concrete

With a rigorous mix design and control of the modulus of elasticity (E_c), recycled aggregate concrete (RCA) can achieve structural strengths comparable to those of conventional concrete [71,72,73]. This technological development has consolidated the inclusion of recycled aggregate concrete (RAC) in international standards, such as the fib Model Code 2020 and Eurocode 2 [74]. Currently, advanced treatments aim to reduce porosity and ionic penetration, focusing on both improving the quality of RCA and separating fines from the hardened cement paste. These fines are reintroduced into the chain as raw material for new cement or for CO₂ sequestration, closing the material cycle [75].

Table 7. Performance outcomes and key findings of studies on Recycled Aggregate Concrete (RAC).

Origin of RCA	Properties Evaluated	Main Findings	Source
Review of ML applied to RCA	Workability, mechanical, durability, ML	Comparison of ML algorithms for RCA prediction; applicability and accuracy discussed	[76]
Composites with various materials	Compressive strength	Cement and recycled content are the most influential factors for strength	[77]
Various RCA datasets	Compressive strength modeling	AutoGluon: CatBoost best performance (RMSE 1.45); cemented the most influential variable	[78]
Meta-study	SSD, absorption, compressive strength, ML	Reduced SSD → 40.5% drop in compressive strength; CNN achieved high accuracy (R2 0.969 training)	[79]
Treatment with silica fume, slag	Strength, durability	Additions improved the strength and durability of RCA	[80]
AI for sustainable mix design	Mix design optimization with AI	AI applied to RCA for sustainable mix design	[81]
ML modeling	Compressive strength using KNN/meta-heuristic	Innovative KNN model; good applicability for RCA prediction	[82]
Database (607 records)	Compressive strength + ML	Hybrid models (GWO-SVR) up to R2 0.9056; cement and absorption key variables	[83]
AI multi-target modeling	Compressive and tensile strength + AI	Random Forest best performance: RCA% and cement are key variables	[84]
Experimental RCA concretes	Compressive strength	ANN model R2 up to 0.97; RCA viable when well-controlled	[85]
Review: RCA modification and treatments	Physical properties, treatments, and durability	Reviews mechanical, chemical, and biological treatments for RCA; promising methods highlighted	[86]
Review: RCA in infrastructures	Strength, permeability, cost-environmental	Shows treatments improve RCA quality; discusses infrastructure applications	[87]
Experimental + ANN applied to RCA.	Compressive strength, ANN modeling	ANN achieved R2 ≈0.97 for RCA compressive strength prediction; replacement is feasible with design adjustments	[88]
ANN applied to RCA	Compressive strength prediction	The proposed ANN predicted RCA compressive strength accurately, which is helpful for mix optimization	[89]
ICA-XGBoost model	Compressive strength prediction (ICA-XGBoost)	ICA-XGBoost outperformed other ML models in RCA strength prediction	[90]

(ML) Machine learning; (RMSE) Root Mean Squared Error (RMSE); (SSD) Saturated Surface Dry; (CNN) Convolutional Neural Network; (AI) Artificial Intelligence; (KNN) K-nearest Neighbors Model; (GWO-SVR) Gray Wolf Optimizer Based Support Vector Regression; (ANN) Artificial Neural Network.

shows the recent advances in RCA performance and Machine Learning modeling.

As illustrated in Figure 5, the reuse of CDW now follows a graded process—from primary crushing to advanced screening—enabling applications of functionally graded concrete (FGC). The use of ML-based predictions and advanced pretreatments (such as regrinding to extract adhered mortar) enables the industry to achieve structural reliability comparable to that of natural aggregates, significantly reducing the sector’s carbon footprint [91,92].

Beyond physical analysis, improving concrete strength with RA involves understanding the complex interaction between the porosity of the bonded mortar and the newly formed Interfacial Transition Zone (ITZ). Recent innovations in machine learning (ML) have changed the approach to strength prediction, using multifactorial optimization models instead of purely empirical formulas [29,83,93]. These models, such as Artificial Neural Networks (ANN) [93], combine essential variables, such as water absorption of fines, the effective w/c ratio, and replacement levels, to understand the nonlinear effects of degradation on compressive strength [94]. Optimization methods now employ hybrid algorithms (e.g., GWO-SVR [83]) to assess how porosity affects the overall elastic modulus, enabling modification of the concrete formulation to increase the water requirements of recycled fines, thereby ensuring structural reliability comparable to that of natural aggregates.

4.3.1. Pre-Treatment and Quality Enhancement

Pre-treatment is summarized as demolition and selective screening to remove unwanted materials (gypsum, metals, plastics, etc.) using magnetic and air separation. Primary/secondary crushing and vibratory screening produce coarse aggregate, fine aggregate, and powder [22,74,91]. Advanced pretreatment techniques contribute to the isolation of bonded mortar and the recovery of fine materials to produce new cement, effectively closing the carbon-materials cycle [95]. These methods include:

• Mechanical/Chemical Abrasion: Abrasion with steel balls and washing with sulfuric acid to produce high-value-added fine aggregates [96].
• Microwave-Assisted Treatment: Generates thermal stress at the mortar-aggregate interface, removing up to 48% of the bonded mortar [97].

Although these approaches improve the quality of coarse aggregate, fine aggregate requires closer supervision due to its greater porosity and water-absorption capacity [98]. Proper selection increases the chances of reusing recycled aggregates in paving and drainage layers, and in structures. However, technological advances must be supported by effective public policies; technology alone is not enough to overcome market barriers. For example, even though Brazil has made considerable progress in research, national supervision and standardized guidelines are still lacking to expand these innovations [95].

4.3.2. Advanced Treatment

The pre-treatment stage involves a thorough classification that enables the initial separation of usable fractions, as previously discussed. However, these materials still have limitations, such as old adhered mortar, high porosity, and microcracks, which impair the mechanical performance and durability of recycled concrete compared with conventional concrete. Advanced treatments can improve the quality of CDW. The pre-treatment stage typically includes chemical treatment, alkaline activation, and carbonation. Subjecting CDW to chemical surface treatment can reduce water absorption and improve bond strength with cementitious matrices [99]. It was observed that the combined use of nano-SiO₂ and sodium silicate in RA improved the mechanical and durability properties of the adhered mortar. According to the authors, chemical treatment tends to fill pores and repair cracks in the mortar as nano-SiO₂ acts. In addition to improving the properties of RA, NMS, when combined with Na₂SiO₃, can promote the formation of secondary C-S-H, thereby enhancing the interfacial transition zone (ITZ).

Tam et al. [100] immersed the RAs in an acidic solution (hydrochloric, sulfuric, or phosphoric acid) at approximately 20 °C for 24 h to remove mortar adhering to the aggregates. This treatment improves mechanical properties by approximately 20%. The chemical treatment reduces water absorption by up to 36.7% and increases bulk density by 5.4% [101].

4.3.3. Alkali Activation

Alkaline activation involves combining aluminosilicate-containing substances (e.g., fly ash, slag, and metakaolin) with alkaline activating agents, such as NaOH and Na₂SiO₃. This process produces a sodium aluminosilicate hydration gel (N-A-S-H) (Figure 6), which functions as a low-carbon geopolymer binder [58,102,103]. This approach has the potential to reduce CO₂ emissions by up to 90% while achieving durability comparable to or even superior to that of traditional concrete [103].

To analyze the relationship between mechanical efficiency and environmental impact, a comparative study of optimized geopolymer compositions was conducted. Given that many existing studies do not present detailed LCA data, a simplified model was used, grouping the research according to its ability to reduce CO₂ emissions and the energy used in the curing process:

• Conservative (±60% reduction): compressive strength < 30 MPa; natural curing or with low molarity solutions.
• Intermediate (65–70% reduction): strength between 35–55 MPa; moderate thermal curing (24–48 h).
• High Optimization (≥75% reduction): strength > 60 MPa. Although high mechanical performance can be achieved with recycled concrete aggregates (RCAs), these processes often require thermal curing, which may partially offset the CO₂-reduction benefits due to higher energy consumption.

From the collected data, a scatter plot was prepared (Figure 7), with the Y-axis representing compressive strength (MPa) and the X-axis representing the estimated CO₂ reduction. The dashed horizontal blue line shows the compressive strength of 70 MPa, while the dashed vertical green line indicates a 70% reduction target in CO₂. Together, these lines define the "Optimized Region" in the upper-right corner, underscoring investigations that achieve both high mechanical performance and significant environmental mitigation. This visualization enabled category segmentation via quadrant division, as suggested by [104]. The relationship between these variables (Figure 7) shows that, as compressive strength increases, CO₂ reduction capacity tends to stabilize or decrease, likely due to the more energy-intensive processes or higher activator concentrations required to form high-strength binders. Although alkali-activated binders have significant potential to give industrial waste a “second life” and significantly reduce the industry’s carbon footprint, their acceptance remains slow due to regulatory barriers and a lack of market momentum [105,106].

4.3.4. Environmental Contribution and CO₂ Uptake

The use of recycled aggregates (RAs) makes concrete a carbon absorber. Recycled Aggregates Concrete (RAC) accumulates CO₂ through carbonation, interacting with cement paste residues to generate stable calcium carbonate (CaCO₃) [75]. Research shows that RA can capture 5–8 kg of CO₂ per ton, depending on particle size and exposure duration [34,114]. Furthermore, Life Cycle Assessment (LCA) indicates that for each 1 MPa increase in compressive strength, emissions increase by approximately 7.23 kg of CO₂-eq, underscoring the delicate relationship between structural performance and environmental impact [115]. In addition to natural effervescence, the rapid effervescence of the recovered fine fraction (as shown in Section 4.3.1) acts as a continuous CO₂ sink [116]. This procedure increases the density of the adhered porous mortar, reducing water absorption and improving mechanical strength, while effectively removing heavy metals from the waste [117]. Industrial activities, such as the company Neustark and research project FastCarb, demonstrate the commercial viability of this approach, which is fundamental for a genuine circular economy in the cement sector [118].

Strategically, recycled materials (RA) reduce the depletion of natural resources and transportation-related emissions by promoting local use [93]. In the European Union and the United Kingdom, robust government policies, along with mandatory recycling targets, have proven effective [49]. In addition to reducing carbon emissions, the use of RA helps minimize the environmental impacts of mineral extraction, such as deforestation and habitat destruction, and strengthens urban resilience against supply chain disruptions caused by extreme weather events [119]. Finally, the incorporation of pozzolanic materials, such as fly ash, slag, and rice husk ash, further reduces the carbon footprint and reduces the need for clinker without affecting durability over time.

4.4. Road Base of Pavement and Soil Stabilization

The CDW used in highway construction is a well-established approach to strengthening the transportation system’s resilience. Crushed waste can exhibit mechanical strength similar to that of natural aggregates, with California Bearing Ratio (CBR) values ranging from 60% to 100% and resilient modulus values (as measured in triaxial dynamic tests) between 150 and 250 MPa [120,121]. Research shows that compositions with entirely recycled aggregates can reduce reflected energy by 30% and greenhouse gas emissions by up to 35% over the pavement’s life cycle [122]. Furthermore, the use of untreated recycled aggregates can reduce the total environmental impact by up to 40% [123]. Soil stabilization further increases pavement durability by improving the bearing capacity and moisture resistance of foundation soils [123]. When ground into fine particles, recycled concrete aggregate (RCD) acts as a pozzolanic material, especially when mixed with small amounts of lime or cement [117]. This enhances the formation of cementing phases and fills voids, resulting in a denser, lower-permeability structure. This stabilization can increase compressive strength by up to 40% compared to traditional soil-cement mixtures while reducing CO₂ emissions by 25–30% [122].

Despite these advantages, the use of CDW in paving is often considered a low-value form of recycling, placing it at a disadvantage compared to applications in structural concrete. A specific logistical challenge persists: construction and demolition waste is generated mostly in urban areas, while paving projects are implemented mostly outside metropolitan areas. Long transport distances can negate environmental gains, contradicting the principles of circularity. Thus, while paving represents a technically viable and financially attractive alternative, it should be seen as a temporary approach rather than a definitive goal for achieving high circularity in civil engineering [124,125].

4.5. Overall Considerations on Valorization, Durability, and Regional Challenges

The use of CDW in civil engineering has strong potential for reuse. According to available technical evidence, these wastes can be processed and subjected to quality control to ensure satisfactory structural performance and mechanical and durability properties comparable to those of conventional materials, whether used as aggregate, a stabilizing agent, or a precursor material. In addition to promoting significant reductions in CO₂ and embodied energy emissions, the use of CDW advances the circular economy and mitigates the environmental impacts of civil construction. However, the general applicability of these approaches must be considered alongside the diverse climatic and geological conditions. In tropical areas, such as Brazil, high rainfall can accelerate CDW degradation by increasing pollutant leaching and organic material decomposition. As Tošić et al. [53] mentioned, it is the high water absorption capacity and porosity of recycled aggregates are further affected by the constant humidity in these environments, requiring more rigorous pre-treatment and storage protocols to preserve the integrity of the Interfacial Transition Zone (ITZ) and overall durability. Thus, to support more sustainable, resilient construction practices aligned with global goals and to reduce emissions of harmful gases, CDW is emerging as a strategic material for this transition.

5. Challenges and Barriers to Circular Valorization and Climate Neutrality

To accelerate the transition to climate neutrality, it is crucial to identify the challenges and limitations in applying CDW. Current barriers represent a significant technical obstacle to circular valorization. The main obstacles to closing material loops in the construction sector are the lack of high-quality standardized processing and the large variability of waste streams [16]. Furthermore, the practice of low-value recycling, which fails to fully exploit CDW’s potential to reduce embodied carbon in new infrastructure, is exacerbated by the absence of integrated policies and economic incentives [126]. Therefore, overcoming these technical and regulatory gaps is a prerequisite for civil engineering to meet the urgent demands of the global climate agenda.

5.1. Material Quality and Variability

The quality and variability of CDW depend on its sources and processing methods [91]. This variability can affect the final product’s performance, necessitating careful quality control. The vast majority of CDW originates from two sources: construction, primarily due to inefficient execution processes that result in material losses, and the demolition, renovation, and repair of existing infrastructure. Studies consistently indicate that CDW is composed mainly of concrete, mortar, and gypsum, with proportions that vary significantly depending on the specific circumstances of each case. Figure 8 illustrates the variability in CDW composition reported across studies.

The collection and separation of CDW generated during new construction are typically the easiest, as material systems are often independent (e.g., masonry, concrete structure, and internal ceilings). However, during renovations, implementing this process correctly is challenging, as the quantities generated at each site are small and are typically disposed of without separation. As a result, the material’s variability is very significant. In addition, for large-scale use, CDW must be collected and transported to a recycling facility to achieve sufficient volume for new construction projects with large areas and/or volumes. Temporal variability must also be considered: although the generated volume is large, the locations of the generation points are typically dispersed, and not all CDW generation occurs simultaneously. These factors pose a challenge to producing CDW with homogeneous properties for large-scale projects. From a climate perspective, this heterogeneity represents a significant obstacle to circular value creation as it often limits recycled aggregates to low-grade applications. Although most standards prescribe a maximum substitution rate of up to 25% of natural coarse aggregate with recycled aggregate (RA) from CDW in structural concrete, caution regarding variability remains essential. The large variation in CDW often requires more cement per cubic meter to ensure structural safety and compensate for possible strength fluctuations. This need directly increases the concrete’s embodied carbon, creating a technical dilemma that can undermine the environmental benefits of recycling. Thus, reducing CDW variability through advanced classification and processing is not only a technical necessity but an essential strategy to enhance the decarbonization of concrete made with recycled aggregates. A critical assessment of the advantages, limitations, and environmental considerations of conventional concrete and concrete with recycled aggregate was conducted by Akbulut et al. [93] and is presented in

Table 8. Critical Assessment of Conventional Concrete (CC) versus Recycled Aggregate Concrete (RAC): Advantages, Limitations, and Environmental Considerations [93].

Criteria	Conventional Concrete (CC)	Recycled Aggregate Concrete (RAC)
Production	✓ Provides high-quality, consistent aggregates. ✖ Requires large amounts of natural resources.	✓ Utilizes construction and demolition waste. ✖ Mix control can be more complex.
Sustainability	✖ Low sustainability potential. ✖ Generates more construction waste.	✓ Supports circular economy principles. ✓ Reduces landfill waste.
Carbon Footprint	✖ High carbon emissions. ✖ Intensive cement consumption.	✓ Reduced carbon footprint. ✓ Lower emissions from extraction and transportation.
Performance	✓ High strength and reliability. ✓ Easier quality control.	✓ Achievable strength with treatment and admixtures. ✖ May have higher water absorption.
Cost	✖ Increasing raw material costs over time ✓ Short-term supply is predictable.	✓ Lower raw material cost. ✓ Avoids disposal fees. ✖ May require pre-treatment investment.
Workability	✓ Predictable slump and flow behavior.	✖ Often reduced due to higher water absorption. ✓ Can be improved with admixtures.
Durability	✓ Long-term performance is well-established. ✓ Proven resistance to environmental exposure.	✖ Potential durability issues without proper treatment. ✓ Can be improved with SCMs and fibers.
Standardization and Codes	✓ Widely covered by national and international standards.	✖ Limited inclusion in design codes. ✓ Increasing acceptance through recent revisions.

.

5.2. Intrinsic Quality Issues of RA

In addition to the variability of construction and demolition waste (CDW), the intrinsic quality of recycled aggregates (RAs) remains a significant bottleneck for high-value-added circular recycling, as their performance is typically inferior to that of natural aggregates. RAs are more porous and mechanically weaker due to the residual mortar adhered to them. This high permeability requires a higher water-to-cement ratio or a higher cement content to maintain consistency, thereby increasing the material’s carbon footprint and reducing its environmental viability [93,133,134,135]. Moreover, the high porosity resulting from the adhered residual mortar poses a complex microstructural challenge, with two Interfacial Transition Zones (ITZs) [136,137], as illustrated in Figure 9, that compromise the mechanical strength and rigidity.

From the perspective of mitigating climate change, the high porosity of recycled aggregate (RA) promotes rapid CO₂ dispersion, thereby accelerating reinforcement corrosion and reducing the structure’s durability (Figure 10).

The environmental impacts of recycled materials can be compromised if construction robustness is reduced, since the carbon impact generated by early replacement outweighs the initial savings [17]. In addition, to ensure long-term sustainability with recycled materials, it is essential to adopt a complete life-cycle view, in which processes that enhance strength become critical [66]. These limitations justify the 25% limit mentioned in the previous section and drive research into advanced pretreatment methods (as discussed in Section 4.1) to improve RA in structural applications and achieve the environmental sustainability objectives of the circular economy.

5.3. Life Cycle Assessment (LCA) and Circularity

By conducting an LCA and comparing the environmental impacts of concrete with natural and recycled aggregates, researchers can identify ways to improve sustainability and inform decision-making [20,65,140]. LCA analysis can help the construction industry adopt more sustainable concrete production practices and focus efforts on reducing environmental impacts. Therefore, it is crucial to recognize that LCA results depend on the system boundary (cradle-to-gate or cradle-to-cradle) and the functional unit used in the study. Including the landfill-diversion benefit may yield an additional 10–40% reduction in GWP relative to studies that use only a gate-to-gate analysis. Transport distance for CDW is also a highly relevant factor, as it can increase impacts by 5–15% in long-distance scenarios, thereby reducing environmental benefits. This insight is essential for standardized reporting and accurate comparisons, as discussed by Marinkovic et al. [66]. However, limited information and public interest in more sustainable buildings reflect low awareness of the construction industry’s environmental impacts. Herranz-Pascual et al. [141] show that, despite positive attitudes, a gap persists between discourse and the adoption of circularity practices. Barriers such as underdeveloped markets and convenience hinder behavioral change. Economic barriers and a lack of information and awareness are the biggest challenges to the circular transition. These barriers are summarized in Figure 11.

The construction industry must overcome economic and information barriers by actively implementing public policies. Evidence of reduced environmental impact, as measured by GWP, supports the use of LCA as a key tool for sustainable construction. Therefore, it is essential to provide information and create contexts that make the adoption of circular-economy practices attractive and straightforward. Both circularity assessment and LCA are complementary approaches, and their integration provides a more comprehensive understanding of environmental sustainability. Although challenging, combining these elements enables more informed choices toward a circular and sustainable economy [36].

Table 9. Quantitative relationship between landfill tax levels and CDW recycling rates (2021–2023 data). Source: Adapted from EEA [144] and European Commission [145].

Country	Landfill Tax for CDW (Approx. €/t)	CDW Recycling/Recovery Rate (%)	Policy Impact Analysis
Netherlands	>€75	>98%	High tax combined with strict landfill bans.
Denmark	€60–€80	>95%	Tax acts as a primary driver for circular economy.
United Kingdom	~€118 (Standard)/€3.5 (Inert)	~90%	Tiered tax encourages sorting of inert waste.
Belgium (Flanders)	€40–€100	>90%	High correlation between cost and diversion.
Italy	€5–€25 (Regional var.)	~75–80%	Moderate tax: results vary by region.
Portugal	<€20	~45–60%	Emerging system; lower tax limits efficiency.
Greece/Romania	Low/Symbolic	<25%	Insufficient economic incentive for the RA market.

correlates the landfill tax value with the CDW recovery/recycling rate, demonstrating the quantitative impact.

Based on Table 9, it is possible to conclude that there is a quantitative correlation between the economic burden of landfill tax and the efficiency of CDW recycling. According to the EEA [144], there is a tipping point in the effectiveness of public policies: countries with taxes above €50/ton achieve recovery rates above 90%. Conversely, in regions where taxes are below €50/ton, the impact coefficient cannot alter the market, resulting in recycling rates below 50%. Thus, this economic elasticity, analyzed in recent econometric models [146], indicates that a €10 increase in landfill fees results in a measurable diversion of waste to recovery centers. From a climate perspective, this change is crucial: high taxes on waste disposal not only encourage the circular economy but also significantly reduce the industry’s overall carbon footprint by preventing methane emissions from landfills and reducing the need for virgin materials, which have high carbon emissions [44]. However, for this to hold, the regulatory framework must also include landfill bans on recyclable materials [145], ensuring that circular valorization remains the most economically and environmentally viable pathway.

6. Future Directions: An Integrated Framework for Climate-Resilient CDW

For construction and demolition waste recycling to reach its full potential in combating climate change, we can no longer treat technological, regulatory, and educational advancements as isolated fronts. The sector’s future demands genuine integration, where digital transformation (Section 6.1) helps overcome the logistical barriers and the lack of trust discussed in Section 5. By aligning automated processing with digital passports and performance standards (Section 6.2), the sector moves beyond simple “waste recycling” and begins to generate high-value assets. This integrated vision ensures that civil engineering decarbonization goals are based on real data and structural safety.

6.1. Integrating Digital Innovation: From Sorting to Traceability

The innovations presented in

Table 10. Technological innovations and their impact on CDW processing.

Technological Innovation	Primary Purpose in Processing	Key Benefit (Climate and Circular Economy)	Source
Automated Sorting Robot	Overcome variability and ensure the high purity and Recycled Aggregate (RA) consistency.	It enables a safer, larger replacement for natural aggregate, reducing perceived technical risk.	[27]
Traceability (Blockchain)	Check the origin, composition, and traceability of each RA batch throughout the value chain.	It increases market confidence and validates sustainability and low-carbon claims.	[147,148]
New Blends (Low Clinker)	Develop high-performance concretes that maximize RA absorption and minimize the need for cement.	Direct reduction in the carbon concrete footprint by replacing clinker with low-carbon materials.	[149,150]
Additive Manufacturing (3D Printing)	Optimize material use and enable prefabricated element development with RA/CDW.	Minimizing in situ waste and accelerating the construction of circular infrastructure.	[151,152]

(formerly Table 8) do not work in isolation; they are interdependent. Automated sorting robots, for example, are the first essential step in ensuring the purity of the material needed for large-scale use. Simultaneously, the development of new low-clinker blends enhances the sector’s environmental gains.

In this scenario, Blockchain technology emerges as a robust solution to one of the oldest problems in the recycled aggregates (RAs) market: distrust in the material’s origin and variability (discussed in Section 5.2). Although uncertainties remain regarding costs and practical implementation, Blockchain is today a more promising tool for ensuring data immutability and traceability. It functions as a digital ledger that tracks destruction from demolition to its final application, directly integrating Life Cycle Assessment (LCA) [148]. As detailed in Figure 12, this network involves multiple participants who validate each step of the chain, increasing market confidence and facilitating the proven reduction in CO₂ emissions [39,147].

The integration of LCA via Blockchain follows a rigorous four-stage structure, according to ISO 14040:2006 [153], ensuring auditable and transparent environmental management (

Table 11. Blockchain-based LCA structure [148]. Reproduced from [148], with permission from Elsevier. This article is under the CC BY license.

1. Goal and Scope Definition	2. Inventory Analysis	3. Impact Assessment	4. Interpretation and Reporting
FU is the specific item with a unique ID.	Primary data collected at the facility level using IoT technologies and supplier questionnaires is allocated to the specific product.	The *LCA software module on the blockchain uses the collected data to perform impact calculations.	Hot spot analysis to identify the most essential processes for impact reduction measures
Scope includes the production of the item (from raw material production), transport, and EoL. The use stage is excluded because of variability in consumer care.	The data were taken from standardized databases.	Selected impact categories may be GHG emissions, water use, land use, and water pollution.	Critical review of data completeness and consistency
Data, and hence LCA results, are refreshed regularly (1–4 times a year) to have up-to-date results.	Several methods of data validation Integration of AI and OCR for data processing		Communication of impact results to consumers through various channels (labels, website, etc.)

Note: * Generic LCA software module proposed in the original study [148]. No primary LCA data processing was performed by the authors of this manuscript using specific software.

).

Blockchain-based LCA structure [148]. (Here you maintain your table with the phases: 1. Objective and scope; 2. Inventory; 3. Impact assessment; 4. Interpretation). This structure enables real-time inventory data to be found via IoT and validated by AI, transforming the LCA from a static report into a dynamic decision-making tool.

Complementing digitization, 3D Concrete Printing redefines what is possible in civil construction, enabling complex shapes that would be infeasible with traditional methods [10]. More than aesthetics, this technology focuses on resilience: through geometric optimization, it is possible to create structures capable of withstanding extreme loads or seismic events with much less material [103]. The great advantage of 3D printing, however, is the drastic reduction in in situ waste and the ability to incorporate high percentages of recycled aggregates and other low-carbon industrial waste [39,152]. In short, the synergy between optimized processing and digital innovation is the bridge to a truly circular CDW management system. By combining the traceability of Blockchain with the precision of 3D printing, we can overcome historical barriers to trust and variability, maximizing the sector’s climate-mitigation potential.

6.2. Development of Performance-Based Standards

Developing performance-based criteria is crucial to shifting attention away from simple mechanical strength and towards the suitability and longevity of buildings constructed with CDW [146,154]. While contemporary research often emphasizes mechanical performance in laboratory settings, future standards should include environmental metrics, such as embodied carbon and Life Cycle Assessment (LCA), to quantify the direct impact of waste management on reducing greenhouse gas (GHG) emissions.

This shift in criteria, from prescription-focused to performance-based, bridges the gap between public policy and materials science. An example of this is the requirement for rigorous protocols to control hazardous substances, such as heavy metals and asbestos, ensuring that recycled materials contribute to a safe, sustainable system without posing environmental risks [103]. Furthermore, to maintain the infrastructure’s resilience, these standards need to assess the behavior of materials under various climatic conditions, including high temperatures and heavy rainfall [155]. Recent research highlights this need by investigating whether permeable concrete made from CDW meets drainage requirements for flood risk management and aligns with public safety criteria.

In essence, harmonizing circular economy objectives with government policies strengthens these standards and builds trust among regulators, investors, and builders. By prioritizing high-quality recycled aggregates for structural applications, these standards foster industry innovation, motivating producers to develop sorting and treatment technologies that meet the most demanding criteria of a low-carbon construction sector.

6.3. Education and Awareness: Fostering a Sustainable and Resilient Culture

The shift to resilient, low-carbon construction depends fundamentally on cultural and educational reforms. It is not enough to pass on knowledge; it is necessary to promote a mindset shift to foster sustainability and resilience across all phases of infrastructure.

Changes in the methodology of academic-professional teaching must be urgently reviewed to address climate change. A key change is the integration of LCA and low-carbon materials into core topics. Herranz-Pascual et al. [141] argue that the lack of instruction on LCA and low-carbon materials undermines practical sustainability efforts. The cultural resistance identified in Section 5.3, often rooted in a lack of technical familiarity with RA, mirrors broader barriers to the Circular Economy. As Tiza et al. [40] point out, this skepticism persists even in regions with high recycling potential. Overcoming it requires more than just advocacy; it demands technical training that bridges the gap between theory and practice. By integrating the climate-driven durability models discussed by Li et al. [156] into professional development, decision-makers can better navigate structural vulnerabilities, while the criteria from Tiza et al. [40] provide a reliable basis for standardizing RA performance.

Promoting a circular economy involves more than just technical data; active action is needed to eliminate the deeply rooted uncertainties about the safety, quality, and even the appearance of recycled materials. As Andrew [157] mentioned, it is essential to educate the public about the environmental and social benefits of circular practices, especially given the high carbon emissions associated with conventional materials such as Portland cement. However, providing information alone is rarely sufficient to change public perception. The author argues that community participation is the true driver of social acceptance of infrastructure that uses CDW. By involving local stakeholders from the outset, developers can foster clear dialogue about performance standards and quality testing, turning skepticism into trust and into collective responsibility for sustainable development.

6.4. Regulatory Instruments and Economic Incentives for CDW Adoption

Only a market- and regulation-based mechanism, backed by robust political support, can ensure supply and demand for recycled materials in civil engineering [158]. Recent findings by Nußholz et al. [19] suggests that the most relevant factors for overcoming companies’ inertia and initial resistance to CDW are mandatory legislation and penalties. In Brazil, laws regulate CDW management, as outlined in the national guidelines summarized in

Table 12. Regulations on fees, fines, and licenses for CDW management in Brazil.

Year	Regulation Name	Content
2002	CONAMA Resolution No. 307 [159]	Establishes the guidelines, criteria, and procedures for the management of the CDW. It classifies waste A, B, C, and D and obliges municipalities to prepare their Integrated Management Plans.
2022	Decree No. 10936 [160]	Regulates the PNRS (Law No. 12305/2010), detailing obligations and instruments, such as Solid Waste Management Plans for large generators, including CDW.
2004	ABNT NBR 15112 [161]	Establishes the guidelines for the design, implementation, and operation of Transshipment and Sorting Areas (TTA) for CDW and bulky waste.
2004	ABNT NBR 15116 [162]	It establishes the requirements for the use of recycled CDW aggregates in pavements and concretes with no structural function, encouraging recycling.
2010	Law No. 12305 (PNRS) [160]	Establishes the national policy that governs all solid waste, including CDW. It defines the shared responsibility and management hierarchy (non-generation, reduction, reuse, recycling, treatment, and final disposal).

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In Brazil, municipalities or states may set the amounts of fines and fees for improper waste disposal. The PNRS demonstrates that there is an incentive: reduced acquisition costs resulting from the tax exemption for CDW recycling companies. The regulations governing fees, fines, and licenses are presented in

Table 13. Regulatory instruments detailing fees, fines, and licensing mechanisms.

Regulation/Law	Core Content in Relation to Fees, Fines, and Licenses
Federal Law No. 12305 (PNRS) [160]	It establishes the responsibility of generators (including CDW) to manage their waste. It determines that non-compliance subjects the company to the sanctions provided for in the Environmental Crimes Law (Law No. 9605/98).
CONAMA Federal Resolution No. 307 [159]	It requires large generators to submit a Civil Construction Waste Management Plan (PGRCC) to obtain the Construction License/Construction Permit.
Municipal Laws, Decrees, and Codes of Postures [163]	They determine collection/disposal fees (when the municipality provides the service), establish fines for irregular disposal (throw-away), and regulate operating licenses for CDW transporters and landfills (ATTs).
State/Municipal Environmental Licensing Regulations [164]	They require an Operating License (LO) for companies that carry out activities in the Transport, Transshipment and Sorting Areas (ATT) and in the Final Disposal of CDW.
Municipal Tax Codes [165]	They can institute the Garbage Collection Fee, which may be levied on the built area or, specifically, on the waste generated.

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Countries such as Finland have adopted landfill fees to discourage landfill disposal [15]. To incentivize the adoption of innovative techniques that promote the use of CDW in higher-value-added applications, Switzerland employs an economic incentive [19]. The European Union already imposes strict technical standards for recycled materials to overcome market distrust of CDW use in the construction industry, thereby reducing the consumption of natural resources and contributing to sustainability and resilience [49]. Recent findings by Huang et al. [59] suggest that the effectiveness of policies lies in two instrument strategies, as follows:

• Push (Regulatory) projects are those that determine the economically illegal and unfeasible destination. One effective instrument is the landfill tax. As Häkkinen and Belloni [15] noted, the landfill tax, in addition to increasing disposal costs, enhances the economic viability of recycling and underscores the need to develop beneficial infrastructure. In addition to penalties, the policy must ensure the development of clear and rigorous technical standards. The lack of certification and quality standards undermines market confidence in CDW’s performance [49].
• Pul (Economic) aims to create demand and reduce adoption costs. The government should establish quotas or bonuses for infrastructure projects that use CDW, with minimum percentage requirements [59]. In addition, tax incentives and subsidies, such as tax exemptions or reductions, are needed to encourage companies to invest in recycling technologies that reduce greenhouse gas emissions [21]. These measures accelerate the development of a more stable market for CDW use in civil construction, aligning with the Circular Economy and climate-mitigation objectives.

In the broader context, Brazil focuses on mandatory regulation and proper distribution for CDW (Pull), while inspection and disposal rates remain very low. By contrast, other countries use these policies to generate demand and make recycling economically viable.

Table 14. Comparative analysis of regulatory and economic Instruments for CDW management: Brazil vs. international frameworks.

Instruments	Feature	Brazil (Legal Framework Approach)	Other Countries (EU, Finland, Switzerland)
Push (Regulatory)	Landfill Tax	Non-existent at the national level. The collection and disposal fees vary by county and are generally not enough to make landfill disposal more expensive than recycling.	Essential (e.g., Finland—cited in the text and in Häkkinen and Belloni [15]. It creates “discouragement” by making disposal illegal and/or economically unfeasible [19,59].
	Quality Norms and Standards	There are ABNT standards (e.g., NBR 15116 [162] for aggregates in floors without structural function), but gaps, a lack of rigor, and a lack of certification undermine market confidence in CDW [49].	Strict technical standards and certification (e.g., European Union). Essential to overcome market distrust and ensure performance, stimulating the replacement of natural resources.
	Mandatory Management Plan	Mandatory for large generators (PGRCC), according to CONAMA 307 [159] and PNRS [160]. Command and Control Tool.	Widely used but complemented by strong enforcement and the direct link to obtaining building permits.
	Tax Incentives for Recycling	There are, such as the cost reduction resulting from the tax exemption for CDW recycling companies (PNRS [160], in theory). Still, the application and impact are limited by low demand.	Essential (e.g., Switzerland—use of incentives for the adoption of innovation techniques and high-value-added applications). Exemptions, subsidies, and funding for recycling technologies [21].
Pull (Economic)	Quotas of Use/Public Contracting	Rare or non-existent at the federal or state level.	Common and effective. The government establishes quotas or bonuses (minimum percentage targets) for the use of CDW in public works [59]. This is the most effective way to generate and secure initial market demand.
	Valuing Innovation and Applications	At an early stage, it was dependent on isolated initiatives or research.	High focus on technological innovation for the use of CDW in higher value-added applications, rather than just low-value landfill/paving [29].

compares Brazil with other countries.

Brazilian legislation provides a basis for managing and reusing CDW; however, additional measures, including high landfill rates (Push) and incentives for technological innovation and demand (Pull), along with guidelines adopted by other countries, are indispensable to ensure scale and RA competitiveness. Transforming waste from an environmental liability into a strategic economic resource is essential to align Brazilian civil construction with the principles of the Circular Economy.

6.5. Improvement and Standardization of LCA Practice for CDW

Although conducting an LCA is essential for measuring the environmental benefits of using CDW over conventional materials, the future challenge is to standardize and improve LCA practice. This analysis provides robust data to support decision-making [14] and promotes a holistic assessment of the environmental effects of material and waste-handling impacts across the entire life cycle. For recycled materials in construction to be considered a sustainable practice, a comprehensive life-cycle assessment is essential to validate their genuine environmental benefits.

The role of LCA in validating the sustainability of CDW is to enable a holistic analysis that avoids shifting impacts from cradle to gate. Recent studies indicate that LCA plays a key role in advancing low-carbon construction [28,36]. Caro et al. [21] reported average reductions of 25–40% in CO₂-eq emissions relative to natural aggregates, based on an LCA of recycled materials in the European Union. Replacing 30% to 50% of natural aggregate with recycled aggregate reduced embodied energy by 18–27 MJ/kg, depending on the energy source and transport mode. Although the use of RA tends to increase transport emissions, this slight increase is consistently offset by eliminating the mineral extraction and quarrying stages. These significant reductions in CWP and Embodied Energy are visually summarized in Figure 13.

Recent findings by Visintin et al. [56] suggest that an LCA shows a slight advantage for RA in terms of emissions, as measured by Global Warming Potential (GWP), due to avoided impacts from natural material extraction, even though RA processing (crushing, screening) is similar to or slightly more intensive than for NA. However, there are significant environmental benefits to reducing resource consumption. Three pillars highlight the relevance of LCA for CDW: reducing impacts (energy consumption and CO₂ emissions), transparency and technical trust, and subsidies and public policies. To promote the practice of LCA, it is necessary that all studies consistently follow a standardized structure, in accordance with the internationally recognized ISO 14040/44 series of Brazilian standards (adopted in Brazil as ABNT NBR ISO 14040/44 [153]), which facilitates the comparison of results and the identification of common critical points, as detailed in

Table 15. Phases and stages of LCA and their relevance to CDW. Source: Developed by the authors based on ISO 14040/14044 [153].

Phase	Title	Main Objective	Contextualization for CDW
1	Goal and Scope Definition	Define the study’s purpose and boundaries.	Objective: To compare the environmental impact of 1 m3 of recycled aggregate and 1 m3 of natural aggregate on the compressive strength of 20 MPa concrete. System Limits: Define whether the final disposal of CDW is an output (by-product) or if the system covers crushing, transport, and application.
2	Inventory Analysis (LCI)	Collect and quantify data on energy and matter inputs and outputs.	Inputs: Quantify the energy consumption (diesel/electricity) in the crushing and transportation of CDW. Outputs: Quantify atmospheric emissions (particulate matter and CO2) from processing and transport. Challenge: Obtain primary data from Brazilian recycling plants.
3	Impact Assessment (LCIA)	Assess the significance of potential environmental impacts.	Classification and Characterization: Translate diesel consumption into (GWP) and emissions at the plant into Ecotoxicity or Photochemical Ozone Formation. Focus: To analyze the categories of Resource Depletion and Climate Change, in which CDW typically offers the most significant advantages.
4	Interpretation	Analyze the results, draw conclusions, recommend actions, and report.	Conclusion: Validate that the benefit of substitution (avoiding virgin production) outweighs the burden of processing (transportation and crushing). Recommendation: Indicate the best applications for CDW or suggest maximum transport distances to maintain the environmental advantage.

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6.6. Machine Learning (ML) Applications

Machine Learning (ML) techniques are used for efficient CDW management, waste generation prediction, and recycling process optimization [27]. These techniques are considered the next technological frontier, capable of addressing critical limitations in quality, variability, and traceability while promoting operational efficiency. Beyond improving efficiency in the construction sector, ML in CDW management can support broader environmental impact goals. Effective energy management depends on accurate predictions to support decision-making and improve resource allocation. Ma et al. [168] demonstrate that ML techniques can significantly improve energy management efficiency. Recent studies referenced in

Table 16. ML applications in CDW management.

Main ML Application	Objective Considering RCA or CDW	Relevance to Sustainability and Climate Change	Source
Hybrid models (ANN, SVR + meta-heuristics) for concrete with RA	Predict mechanical properties (e.g., compressive strength) from mixing parameters and characteristics of the recycled aggregate.	Reduces the need for destructive testing and optimizes dosages, reducing material and energy consumption	[83]
ML review in CDW management (CNN, SVM, RF, etc.)	Systematize ML uses in the generation, sorting, logistics, and recycling of construction and demolition waste	Indicates that ML can increase recycling rates and reduce shipments to landfills, contributing to a lower carbon footprint of construction	[27]
ML + sensitivity analysis for “green RCA”	Model and optimize green concretes with RA, evaluating mixing variables and mechanical performance	Supports the design of more sustainable concrete, reducing the use of natural resources and environmental impacts	[77]
Artificial intelligence for sustainable mix design of RCA	Define sustainable concrete traces with RA using AI, considering performance and emissions	Integrates mechanical performance with eco-efficiency criteria, supporting low-carbon decisions in mix design	[169]

ANN = Artificial Neural Networks; CNN = Convolutional Neural Networks; SVM = Support Vector Machines; RF = Random Forests; AI = Artificial Intelligence; RA = Recycled Aggregate; ML = Machine Learning; RAC = Recycled Aggregate Concrete; CDW = Construction and Demolition Waste.

indicate that intelligent models can optimize logistics routes, predict mechanical properties, improve sorting, and support low-carbon environmental analyses.

The implementation of advanced technologies for CDW treatment, such as automated sorting robots, provides a techno-economic balance, according to Visitin et al. [56]. This cost–benefit ratio, although these systems require a higher initial investment, is optimized by the increased structural reliability of the final product resulting from the production of high-purity recycled fractions. Long-term benefits, including significant reductions in emissions and resource depletion through high replacement rates of natural aggregates, compensate for the processing energy required [166]. These advantages are systematically evaluated through Life Cycle Costing (LCC) and environmental allocation models. To demonstrate how the initial investment is offset by life-cycle benefits,

Table 17. Economic feasibility and environmental impact of automated and on-site CDW processing technologies.

Technology	Initial Investment	Long-term Economic Benefit	Environmental Dividend	Refs.
Automated Sorting	High	Reduced labor & High-purity RA.	Optimized substitution rates.	[31,32]
Mobile Crushing (Inferred/Logistic context)	Moderate	Logistics cost reduction.	Lower CO2 from transport.	[55,56]
AI Quality Control	Moderate	Real-time certification.	Waste contamination reduction.	[169]

summarizes the economic viability and environmental performance of the main treatment technologies.

The high accuracy achieved by ML models is key to transitioning from the laboratory to industrial applications. Models such as ANN, SVR, CNN, and hybrid algorithms provide high confidence in ML-based systems, achieving high accuracy (R² > 90) in predicting the properties of recycled materials [169]. Gao, Wang, and Xu [27] highlight the use of ANN, SVM, RF, and CNN for forecasting waste generation, classification, and automated logistics optimization. Recent findings by authors suggest that these models improve sorting accuracy compared with manual methods, thereby increasing the overall efficiency of recycling systems. The approaches applied to smart logistics and environmental estimates enable the identification of lower-emission scenarios and the optimization of transport and recycling flows, as shown in

Table 18. ML models employed and variables of interest in RCA/CDW.

ML Models Addressed	Key Variables/Output Models	Central Contribution	Source
ANN, SVR, and hybrid models with optimization algorithms (e.g., GWO-SVR, PSO-SVR)	Compressive strength and mechanical properties of concretes with RA.	They show that hybrid models capture complex nonlinear relationships between RA properties, trace, and resistance, with high predictive accuracy.	[169]
Various algorithms (ANN, SVM, Random Forest, CNN, etc.) in CDW studies	CDW generation, waste sorting, recycling fees, collection, and transportation logistics	Review that maps where ML is already effective (screening, generation prediction) and where there are gaps, especially in the integration with environmental indicators and LCA	[27]
ML models combined with sensitivity analysis (variance-based)	Strength, mechanical performance, and sensitivity to mixing parameters in “green RCA”	Identify which variables (e.g., RA fraction, mineral additions) most influence performance, facilitating optimization of sustainable blends	[77]
AI/ML models for optimal mix design (ensemble and other approaches)	Concrete mix proportioning, mechanical properties, environmental indicators (energy, emissions)	Integrate AI with eco-efficiency criteria, proposing a sustainable blend of RCA that reduces emissions while maintaining adequate performance	[169]
Review of ANN, SVM, trees, ensembles, GBM, applied to RCA	Workability, Strength, Elastic Modulus, Durability, Overall RCA Performance	It makes a critical synthesis of the advantages and limitations of each algorithm and suggests good practices for variable selection, calibration, and validation of models for RCA	[76]

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In general, the studies in this section present a CDW-focused ML model that enables greater control over recycled aggregate quality, more reliable environmental analyses, and more accurate projections of structural performance. These studies clearly show that integrating ML algorithms is essential to building a more sustainable, resilient construction system that helps achieve the global goal of reducing harmful gas emissions.

6.7. Overall Considerations on the Integrated Framework and Future Perspectives

The coordinated integration of technological, regulatory, and educational advances is essential to maximizing CDW’s climate-mitigation potential. Methodologies that employ processing technologies, such as automated sorting systems, digital traceability tools, and 3D printing with CDW, improve CDW quality for construction use, thereby increasing reliability. However, different climatic and geological conditions must be considered when developing universal strategies, as heavy rainfall in tropical regions can accelerate waste degradation through leaching and organic decomposition. To maintain the material integrity, more rigorous pre-treatment is necessary [26]. Incorporating knowledge of low-carbon materials, LCA principles, and circular-economy strategies from the next generation of engineering is fundamental to overcoming existing cultural resistance. Methodological advances, such as machine learning [83] and Digital Twin technology [29,39], enable predictive modeling, real-time monitoring [93], and efficient resource management. When coupled with LCA and social-environmental cost–benefit models, these tools ensure transparent quantification of environmental benefits and accelerate the transition to a circular, low-carbon, and data-driven construction sector [56,166]. Thus, if all the guidelines discussed in Section 6 are implemented in an integrated manner, it will be possible to increase the efficiency of recycled material reuse and help meet global decarbonization targets, thereby promoting more sustainable and resilient construction in the coming decades.

7. Final Remarks

Today, the global climate presents significant challenges for civil engineering but also offers opportunities for innovation and leadership in developing sustainable and resilient infrastructure. Conserving natural resources and reducing waste are key strategies for mitigating climate change, and recycling CDW is part of this effort. Based on an analysis of current practices, challenges, and future technological directions, the following main conclusions stand out:

• Environmental Validation: The environmental advantage of using RA is consistent and has been demonstrated through LCA studies. Using the LCA method, it is possible to verify a significant potential to reduce global warming and embodied energy (reductions of 25–40% in CO₂-eq), thereby confirming RA’s fundamental role in low-carbon construction.
• Persistent barriers: Economic challenges (such as perceived upfront costs and limited market competitiveness) and regulatory fragmentation (e.g., Brazil’s hard 20% threshold for structures, compared with flexible standards in the European Union) hinder the transition to circularity.
• Need for standardization: Standardizing LCA practices, including system boundaries and functional units, is an essential future guideline to ensure comparability of results and promote technical confidence.
• Technological imperative: Machine Learning (ML) and Blockchain are advanced technologies that help overcome market mistrust. While Blockchain ensures the traceability and integrity required for large-scale structural applications of recycled aggregates, ML provides high-accuracy predictions (R² > 90) of material properties.
• Policies and Infrastructure: Implementing local policy networks and expanding CDW processing infrastructure are essential to ensure the quality and consistency of RA supply.

Civil construction can play a vital role in creating a more sustainable and resilient future by implementing public policies and deploying advanced supporting technologies. In addition, expanding CDW infrastructure, supported by local policy networks, can help mitigate climate change by providing long-term carbon storage.