Construction and demolition waste (CDW) represents-35% of global waste and-40% of related emissions. Recycled aggregates from CDW support sustainability and circular economy strategies. This study investigates the enhancement of recycled concrete and ceramic aggregates using graphene oxide (GO) nanocoating, applied without coupling agents. The coating removes fine particles from aggregate surfaces and provides waterproofing. Ceramic particles, due to higher porosity, absorb more GO than concrete particles. Experimental results show water absorption reductions of 19% (concrete) and 25% (ceramic) aggregates. GO forms a uniform layer, decreases microporosity, preserves surface roughness, and reduces particle detachment by 17% and 25% for concrete and ceramic aggregates, respectively. SEM analysis confirms a pore-filling effect consistent with waterproof behavior. These findings demonstrate the GO nanocoating effectively improves durability and performance of recycled aggregates, offering a practical route towards sustainable construction materials.

Accurate object detection is crucial for managing construction and demolition waste (CDW). However, existing deep-learning models often exhibit limited performance in detecting small objects within complex environments. This study proposes a YOLOv11-based detection algorithm integrated with a novel Cascaded Group Attention (CGA) mechanism to enhance the model's ability to capture fine-grained features while significantly reducing computational and memory costs. First, we propose a transformer backbone based on CGA to improve long-range dependency modeling while substantially reducing redundant computations. Second, we employ a bidirectional multi-scale interaction module in the neck to integrate fine-grained details from high-resolution features with semantic context from low-resolution features, enabling accurate detection of CDW objects across scales. Finally, the proposed method is evaluated on two datasets. For comparison, we have reproduced several similar YOLOv11-based algorithms to validate the effectiveness of our approach. The results demonstrate a clear advantage of our approach, achieving mAP scores of 0.938 and 0.962, respectively, thereby surpassing the current state-of-the-art methods. Additionally, visualization of prediction results on test samples further confirms the high accuracy of our model. The data and code for this research can be obtained at the following link: https://github.com/jzp-csust/CDW.

ABSTRACT Increasing demand for eco-friendly building materials has motivated investigations toward alternative resources and waste utilization in construction domain. This research article concentrates on the manufacturing of unburnt bricks with reduced quantities of binder materials (lime, fly ash and gypsum) compared to conventional fly ash, lime and gypsum (FaL-G) bricks. Also, this study concentrates on the complete replacement of manufactured sand with waste foundry sand (WFS) as a filler component. Brick mixes comprising lime-10%, waste marble powder (WMP) −10%, WFS-20%, grinded construction and demolition waste (CDW) varying from 0–30% and fly ash (FA) varying from 30–60% were cast and evaluated for their mechanical, thermal and durability properties. Morphological and elemental characterizations were made on the samples utilizing scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD). Brick mix FA50WM10 containing 10% CDW gave the highest compressive strength of 12.11 MPa, equating to class-10 bricks as per Bureau of Indian Standards. Thermal and durability parameters of bricks manufactured using the above ingredients performed better compared to conventional bricks. The study is novel in reducing the cementitious materials content to 50% and completely utilizing WFS in the place of manufactured sand compared to other brick types. These bricks have the potential to minimize natural resource consumption and also enhance sustainability and circular economy in brick manufacturing.

This study focuses on paving block composites using fine aggregate from brick construction and demolition waste (CDW). The study addresses two issues that contribute to excessive resource extraction, environmental degradation, and rising material costs in urban construction: the steadily increasing production of brick CDW and the growing reliance on natural sand in the production of paving blocks. The accumulation of brick CDW in landfills and uncontrolled disposal further emphasizes the need for technically and economically feasible alternative material solutions. The results demonstrate that recycled brick CDW aggregates can be seamlessly incorporated into cement-based paving composites due to their complementary mineral compositions. Mechanical testing confirms that paving blocks made from recycled CDW have a noticeably higher compressive strength than natural sand. This performance improvement is caused by the rough surface and angular particle shape of brick CDW. These elements enhance the cement matrix's and aggregate's mechanical interlocking, creating a stronger composite structure. Furthermore, comparative analysis demonstrates that paving blocks manufactured with recycled brick CDW can achieve up to two times higher compressive strength while reducing production costs by about 50% when compared to conventional combinations. These findings suggest that recycled brick aggregates outperform natural sand in terms of cost and structural soundness. These findings suggest that recycled brick aggregates outperform natural sand in terms of cost and structural soundness. The study's findings can be used to support more resource-efficient and environmentally friendly building techniques, particularly in urban areas where brick demolition waste is easily accessible

The construction industry is one of the largest contributors to global waste generation, ranking among the top producers of solid waste worldwide. Within the context of construction and demolition waste (CDW), the cementitious fraction stands out as the only component capable of capturing atmospheric carbon dioxide (CO2) and as a viable source of supplementary cementitious material (SCM), thereby mitigating the environmental impacts associated with the anthropogenic CO2 emissions of cement production. This study aims to evaluate the potential of low-energy grinding to enrich the cement paste content in cementitious waste fines. Various grinding conditions were investigated, including different energy levels, ball loads and ball diameters, while maintaining a constant mill filling. The chemical composition in the size fractions, both before and after selective grinding, was determined using X-ray fluorescence. The results indicated that autogenous grinding was not effective because it produced only a small mass fraction of fines (<0.15 mm). The combination of 40 mm and 6.3 mm steel balls yielded the best performance in the conditions tested herein, promoting the migration of cement paste from the coarse fraction to the sand and fine fractions (<4.8 mm); however, the enrichment of cement in the finest fraction (<0.15 mm) remained limited.

Abstract The ecotoxicological evaluation of construction and demolition waste (CDW) is essential for its sustainable reuse, but assessment is challenged by the characteristically high pH of its leachates. This study performed a comparative evaluation of three plant-based bioassays ( Lemna minor , Desmodesmus subspicatus , Sinapis alba ) to identify the most robust method for assessing the phytotoxicity of seven distinct CDW leachates under environmentally relevant, unadjusted pH conditions. Furthermore, a validation experiment with model compounds (CaCl 2 , Ca(OH) 2 , NaOH) was conducted to unequivocally isolate the primary drivers of the observed growth inhibition. The L. minor bioassay demonstrated superior performance, showing clear, dose-dependent inhibition where the algal and mustard seed assays showed limited applicability due to pH tolerance or methodological constraints. Chemical analysis and validation experiments confirmed that the severe phytotoxicity of fresh CDW leachates is driven primarily by high alkalinity (pH > 11) and the associated buffering capacity, rather than by leached trace elements or specific ion phytotoxicity. High calcium concentrations at neutral pH induced only negligible, sublethal stress. We conclude that the L. minor bioassay is a sensitive and discriminating tool for this challenging matrix. Our results demonstrate that high, stable pH is the primary factor of phytotoxicity in CDW leachates, and that calcium concentration serves as a reliable indicator for this hazard. Testing unadjusted leachates provides an environmentally relevant approach for guiding the safe and sustainable management of CDW. Graphical Abstract

In China, a significant portion of construction and demolition waste (CDW) consists of clay bricks and concrete, which can be processed into recycled brick-concrete aggregate (RBCA). This study explores the utilization of compositely modified RBCA as a substitute for natural coarse aggregate in concrete. Two distinct composite modification methods were applied to pretreat RBCA, and then the resistance of the resulting recycled brick-concrete aggregate concrete (RBCAC) to sulfate attack and freeze-thaw cycles was systematically examined and elucidated the underlying enhancement mechanisms. The experimental data revealed a clear trend: increasing the proportion of RBCA in the concrete mix correlates with a marked decline in its durability performance. In contrast, the application of composite modification techniques yielded a significant enhancement in durability. This improvement is primarily attributed to the mitigation of weak interfacial zones and the promotion of a more compact microstructure within the interfacial transition zone (ITZ). Consequently, the observed enhancement in durability metrics can be principally ascribed to this microstructural optimization. This research offers substantive theoretical insights that can facilitate the broader adoption of compositely modified RBCA in the production of sustainable concrete, contributing to waste valorization and resource conservation.

Rapid urbanization is driving sharp growth in construction and demolition waste (CDW), making recycling facility selection and transport planning critical for cost-effective and sustainable urban waste management. This paper presents an end-to-end, simulation-driven decision-support framework that jointly optimizes facility selection and operational waste transportation policies under uncertainty, and systematically benchmarks competing solutions using Data Envelopment Analysis (DEA). The proposed approach embeds a metaheuristic optimization engine within a Monte Carlo simulation environment to evaluate facility configurations and dispatch–allocation decisions under stochastic waste generation and operating conditions, using sample-average performance to ensure fair and consistent comparison across scenarios. Results from the Wuhan metropolitan case study show that coordinating dispatch intensity with contracted facility capacity significantly reduces total cost and unmoved waste while stabilizing performance across stochastic realizations; DEA then provides transparent efficiency-frontier ranking across economic, operational, and environmental indicators without requiring pre-specified weights. These findings demonstrate that dispatch–capacity alignment is a dominant lever for robust and sustainable CDW logistics, and that DEA-based benchmarking enhances decision transparency when multiple near-optimal solutions coexist.

ABSTRACT Due to rapid urbanization and population growth in recent years, the global construction sector has expanded significantly, accompanied by serious environmental challenges. One of the most pressing issues is the generation of construction and demolition waste (CDW), which is heterogeneous, widespread and voluminous. This article critically examines the effects of CDW on wetland ecosystems focusing on Diepsloot and Tembisa in Johannesburg and Ekurhuleni Municipalities. Using a mixed-method approach that combines semi-structured interviews and remote sensing techniques, the study demonstrates how CDW disrupts the physical and ecological functions of wetlands. The findings confirm that CDW causes physical alteration of wetland landscapes, disrupting water flow, sedimentation patterns and natural hydrological processes essential for wetland functioning. The accumulation of CDW in wetlands results in water pollution, degrades water quality and contributes to biodiversity loss through habitat destruction and disruption of species’ breeding patterns. Furthermore, obstruction of natural drainage systems exacerbates flooding and further destabilizes these ecosystems. The article underscores the urgent need for improved waste management practices and stronger regulatory enforcement to mitigate the harmful impacts of CDW. Without meaningful reforms, continued wetland degradation threatens critical ecosystem services, including water purification, flood regulation and habitat provision.

The destructive power of major earthquakes and urban transformation processes significantly affect the type and quantity of construction waste. Construction and demolition waste (CDW), which increases in quantity every year, faces both storage and disposal problems. Sustainable solution strategies and alternatives should be developed for the replacement of CDW. In this context, the effects of replacing the aggregate with different proportions of concrete waste, ceramic waste, and glass waste—among the most important construction and demolition wastes—were evaluated for mortar in the experimental study. CEM-I 42.5R cement was used in the study, and the water-cement-aggregate ratio by weight was kept constant at 1-1-4. A total of 90 cubic specimens measuring 50 x 50 x 50 mm were produced for 1 reference and 9 replacement scenarios. A series of physical measurements and compressive strength tests and microstructure analysis were performed on all specimens cured in saturated water at 20 ± 2 °C for 7 and 28 days. Experimental results show that all series, except for the series with 15% concrete aggregate substitution in mortar mixes, have higher compressive strength than the reference series. Therefore, the compressive strength provides acceptable performance at the substitution rates used for concrete, ceramic, and glass waste. Therefore, this study, based on compressive strength analyses, demonstrates that concrete, glass, and ceramic waste aggregates can be reused in masonry mortars.

The construction of the base course relies heavily on conventional aggregates, leading to a significant depletion of natural resources. This study explores the use of construction and demolition waste (CDW) as an alternative to natural aggregate as a base course material in low-volume roads. Furthermore, the impact of using cashew nut shell liquid treated coir geocell reinforcement as a sustainable, durable and high-performance reinforcement to enhance the structural performance of the base course is also studied. The research involved conducting monotonic and repeated plate load tests on a flexible pavement model, revealing that coir geocell reinforcement significantly improved bearing capacity and modulus of subgrade reaction, with CDW performing better than natural aggregates. The Modulus Improvement Factor (MIF) ranged from 1.21 to 1.7 for natural aggregates and from 1.33 to 1.88 for CDW. Reinforcement with coir geocell was highly beneficial under repeated loads too. This reduced the plastic deformation and increased the elastic settlement of the pavement by facilitating better stress redistribution and particle interlocking. The study also proposed an analytical formulation to determine the effect of coir geocell wall flexibility on load-carrying capacity.

This study aimed to examine the impact of various production parameters on the shear performance at the interface between geopolymer mortar (GPM) and sand soil. Initially, the effects of varying NaOH concentrations (5, 10 and 15 M), aggregate types (stream aggregates (SA), crushed stone aggregates (CS) and construction and demolition waste (CDW) aggregates) and alkali/binder ratios (0.5 and 0.6) on GBFS-based GPM specimens were investigated. For this purpose, compressive strength, water absorption and ultrasonic pulse velocity (UPV) tests were carried out on GPM samples cured for 28 days. The maximum 28-day compressive strength (43.6 MPa) and the minimum water absorption (3.78%) were observed in GPM specimens activated with 15 M NaOH, produced with CS, water-cured and cast at an alkali/binder ratio of 0.5. Experimental findings revealed that the effects of aggregate type on high mechanical and low permeability properties were graded as CS > SA > CDW. Additionally, UPV test results showed positive correlation with compressive strength and water absorption values. Subsequently, the shear performance between GPM and sand soil were determined by using shear box test. In direct shear experiments, decreasing the alkali/binder ratio from 0.6 to 0.5 and the usage of CS increased the sand–GPM friction angle. Moreover, numerical modelling was employed to analysed soil-GPM interaction using the finite element method (FEM) in ABAQUS. FEM results showed that the obtained numerical findings demonstrated strong consistency with experimental data, capturing force–displacement trends therefore the numerical model can be used for parametric studies.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-33002-w.

Among Construction and demolition waste (CDW) has become a persistent challenge for urban sustainability, particularly in developing countries where institutional capacity and market coordination remain limited. While the reuse of CDW is widely recognized as technically feasible, its commercialization continues to face underlying obstacles. This research examines the factors limiting the consolidation of the CDW market in Maceió, Northeast Brazil, a city that recently experienced a large-scale geotechnical disaster and a sudden increase in CDW generation. The analysis is guided by the question: Which factors most strongly constrain the development of the CDW market in Maceió, and how do they interact? A mixed-methods design was adopted, combining survey data analyzed through the Relative Importance Index (RII), descriptive statistics, and ANOVA with semi-structured interviews involving professionals from construction, waste management, and public agencies. The results reveal five interconnected groups of barriers. The most influential are the absence of effective public policies (RII = 0.89), lack of fiscal incentives for recycling (RII = 0.88), fragmented legislation (RII = 0.87), and the systematic devaluation of recycled materials (RII = 0.85). Environmental constraints linked to land subsidence (RII = 0.90) further intensify market instability. Together, these findings show that CDW commercialization is shaped by interacting regulatory, economic, and cultural factors, underscoring the need for coordinated policy, fiscal, and governance responses in vulnerable urban contexts.

Fiber-reinforced polymer composites (FRPCs) are increasingly used in construction due to their high performance and low environmental footprint. However, their widespread adoption has raised concerns over end-of-life management, particularly under European regulations mandating high recycling rates for construction and demolition waste (CDW). This study evaluates different systems for the chemical recycling of FRPCs through microwave (MW)-assisted solvolysis using green solvents, including deep eutectic solvents (DESs) and biobased acetic acid. The process targets thermoset resin depolymerization while preserving fiber integrity, operating at reduced temperatures (≤230 °C) and lower energy demand than conventional techniques, such as pyrolysis. A systematic experimental design was applied to CDW-derived polyester composites and extended to industrial epoxy and vinyl ester composites. Among the tested solvents, glacial acetic acid + ZnCl2 (5 wt.%), achieved the highest degradation efficiency, exceeding 94% in small-scale trials and maintaining over 78% upon upscaling. Recovered fibers showed moderate property retention, with tensile strength and elongation losses of ~30% and ~45% for infusion-based epoxy composites, while those from pultrusion-based epoxy composites exhibited 16–19% and retained similar properties to the virgin material, respectively. The method facilitates fiber recovery with limited degradation and aligns with circular economy principles through solvent reuse and minimizing environmental impact.

The construction industry's heavy reliance on Ordinary Portland Cement (OPC) significantly contributes to global CO2 emissions, prompting the search for sustainable alternatives. This study investigates the partial substitution of Portland cement with construction and demolition waste (CDW) powder and concrete waste (CON) powder in mortar mixes. Replacement levels of 5%, 10%, 15%, and 20% by weight were tested following EN 196-1 standards to evaluate the mechanical performance of the resulting materials. X-ray diffraction (XRD), X-ray fluorescence (XRF), and thermo-gravimetric analyses confirmed that CDW and CON powders consist mainly of quartz and calcite, with chemical compositions compatible with cementitious systems. Mechanical testing revealed that compressive strength was maintained or slightly improved at replacement levels up to 10%, while higher substitutions led to moderate reductions due to dilution effects. The use of CDW and CON powders effectively transformed a 52.5 R Type I cement into a 42.5 R Type II equivalent, demonstrating the feasibility of producing sustainable binders with acceptable performance.

To meet 2050 climate targets, the construction sector must reduce CO2 emissions and transition toward circular material flows. Recycled aggregates (RA) derived from construction and demolition waste (CDW) and industrial byproducts such as oil shale ash (OSA) show potential for use in concrete, although their application remains limited by standardisation and performance limitations, particularly in structural uses. This study aims to develop and evaluate low-strength, resource-efficient concrete mixtures with full replacement of natural aggregates (NA) by CDW-derived aggregates, and partial or full replacement of cement CEM II by OSA–metakaolin (MK) binder, targeting non-structural 3D-printing applications. Mechanical performance, printability, cradle-to-gate life cycle assessment, eco-intensity index, and transport-distance sensitivity for RA were assessed to quantify the trade-offs between structural performance and global warming potential (GWP) reduction. Replacing NA with RA reduced compressive strength by ~11–13% in cement-based mixes, while the aggregate type had a negligible effect in cement-free mixtures. In contrast, full cement replacement by OSA-MK binder nearly halved compressive strength. Despite the strength reductions associated with the use of waste-derived materials, RA-based cement-free 3D-printed specimens achieved ~30 MPa in compression and ~5 MPa in flexure. Replacing CEM II with OSA-MK and NA with RA lowered GWP by up to 48%, with trade-offs in the air-emission, toxicity, water and resource categories driven by the OSA supply chain. The cement-free RA mix achieved the lowest GWP and best eco-intensity, whereas the CEM II mix with RA offered the most balanced multi-impact profile. The results show that regionally available OSA and RA can enable eco-efficient, structurally adequate 3D-printed concrete for construction applications.

Abstract Construction and demolition waste (CDW) are commonly disposed of in unlined landfills or inappropriately at irregular sites. Civil construction materials may contain hazardous substances that, if solubilized or leached, can negatively impact the environment and human health. Understanding the leaching behavior of CDW is essential for assessing its environmental performance and ensuring its safe reintegration into the construction supply chain. This study aimed to investigate the impact of paint presence on the leachate contamination potential. The method involved the UNE-EN 12457-3 compliance leaching test and column percolation tests conducted under both saturated and unsaturated conditions, using columns filled with CDW, with and without paint. The samples, regardless of the presence of the paint layer, were classified as non-hazardous according to the criteria established by the European Council. The results indicate that the presence of paint mainly influenced the apparent color, turbidity, and concentrations of Na + and K + in the leachate. Although various heavy metals are used in paints, especially as pigments, the presence of paint in CDW did not significantly influence the release of these metals into the leachate. The CDW leachates, regardless of the presence of paint, exhibited potential for groundwater contamination due to elevated levels of sulphate and total dissolved solids. Notably, CDW also demonstrated the capacity to remove Zn and Fe and CDW without paint was found to reduce water turbidity.

The construction sector faces the dual challenge of reducing energy consumption and mitigating the environmental burden of construction and demolition waste (CDW). Geopolymers offer a low-carbon alternative to Portland cement, yet their performance depends strongly on precursor composition. This study presents an extensive investigation of precursor chemistry, mechanical performance and phase composition, focusing on the partial substitution of ground granulated blast furnace slag (GGBFS) with mechanically activated CDW powder (15% and 30% by weight) alongside fly ash (FA). The oxide composition, amorphous content and particle size distribution were analyzed, using XRF, XRD and laser diffraction to evaluate the reactivity. Mortar samples were subsequently synthesized and tested for compressive and flexural strength, ultrasonic pulse velocity, density and porosity. The results demonstrate that while mechanically activated CDW incorporation decreases early strength compared with GGBFS-rich systems, compressive strengths above 45 MPa were attained at 28 days, with continuous improvement to >69 MPa for aged composites. The relationship between precursor chemistry, precursor sizes and mechanical performance highlights the feasibility of CDW valorization in geopolymer binders, contributing to energy efficiency, circular economy strategies and sustainable construction materials.

With the increasing population, the rapid urbanization and construction needs have led the construction sector to consume significant amounts of natural resources and generate large-scale waste. One of the fundamental building materials of the construction industry is concrete. However, its use and production result in high carbon emissions and energy consumption. In this context, the recycling of concrete, which is a key material in the sector, and the use of recycled concrete aggregates (RCA) emerge as significant solutions for reducing environmental impacts and aligning with the principles of the circular economy within the framework of sustainable construction. Study focuses on the production process, usage standards, application areas, and benefits of recycled concrete aggregates obtained from construction and demolition waste are discussed. It has been determined that RCA, which has certain quality differences compared to natural aggregates, is widely used in road infrastructure, fill materials, drainage systems, and specific structural elements. Additionally, within the scope of the technical standards in effect in Turkey and worldwide, RCA can be used in concrete production at certain proportions. However, in terms of strength, it requires a more careful engineering process compared to natural aggregates. This article evaluates the impact of recycled concrete aggregates on sustainable construction and presents recommendations for the future of the construction sector within the framework of zero waste and circular economy principles. The results indicate that recycled concrete aggregates offer a significant alternative from environmental, economic, and engineering perspectives and should be encouraged for wider use in the coming years.

Construction and demolition waste (CDW) constitute a menace in Zimbabwe. The industry’s image is tainted by rampant disposal on roadsides, in watercourses, and in landfills. Concerted practical efforts to proffer solutions to the problems of CDW disposal have achieved little. Therefore, this study aimed to develop a lean-based framework that could help reduce the impacts of CDW. An in-depth review of the related literature was conducted to establish that lean construction approaches have been adopted to minimise CDW. The literature review led to the compilation of a semi-structured questionnaire used to expedite survey research, which received insights and perspectives from 260 construction personnel gathered through a purposive sampling technique. The top-ranked lean CDW minimisation framework embeds recycling, recovering, and reuse, Kaizen (continuous improvement), Last Planner System (LPS), Just-in-Time (JIT), and Andon (visualisation). The four-step framework shows potential for reducing CDW in Zimbabwe and similar regional contexts. Some of the findings show that the recycling technologies needed to recycle construction waste are not yet available in Zimbabwe. The available regulatory frameworks are not very clear on using recovered, salvaged, and recycled construction materials. Designers are not designing in a way that controls waste streams on sites.