Demolition Waste Research Articles

An Image‐Based Approach to Automated Recognition of Asbestos‐Containing Components in Wall Demolition Waste

AbstractThe feasibility to discriminate potentially asbestos‐containing components from asbestos‐free concrete based on camera images using the example of wall demolition waste is investigated. For this, three types of asbestos substitute materials and two types of concrete are crushed and photographed. The classification of the fragment images is carried out with a) morphological and texture features and b) with features automatically extracted by the pretrained MobileNetV3 network. Feret diameters, circularity, and others served as morphological descriptors. The texture was described by measures of grey‐level intensity, as obtained from the grey‐level co‐occurrence matrix. Support vector machines are found to achieve classification accuracies above 99 % based on the automatically extracted features. The presented identification approach is promising to automate the treatment process of asbestos‐containing materials from construction and demolition waste, which is effortful and requires expert knowledge to this day.

Environmental Management Framework for Road Network Demolition Wastes for Construction Industry of Pakistan

Demolition waste from construction industry, especially from road networks, is one of the most voluminous and harmful categories of waste worldwide; therefore, its proper handling is essential for sustainable waste management for environmental, social, and economic benefits. Prolific and unregulated construction activities, conflicts, and defective works are major reasons. The current work aims to address the issue by presenting a framework for an enhanced understanding of sustainable demolition waste management (DWM). A critical analysis of the literature aided to identify major concerns related to different causes, their impacts, and challenges being faced by the construction industry in such management endeavors. The study adopted questionnaire-based methodology to understand the critical relation among the three variables. The Delphi technique supported by industry professionals and pilot study helped to formulate a realistic questionnaire tool. Using the concept of multivariate statistical analysis, structure equation modeling (SEM) helped to assess the structural relationships between the three variables. The research instrument met the reliability, validity and internal consistency criteria required. Each variable achieved a high effect size, f2, with a value of co-efficient of determination of more than the threshold value of 70%. Thus, this supported the fitness criterion of the SEM-based measurement model. Path coefficients yielded the acceptance of all alternate hypotheses, resulting in a strong positive relationship among the three constructs. Therefore, demolition waste impacts are deemed as an effective mediator when explaining the impact between the other two variables. The developed framework presents a coherent and systematic approach and identifies strategies that could be used to address these issues and lead to DWM, including options available for capacity building and implementation and evaluation for supporting sustainability.

Nanocomposites Derived from Construction and Demolition Waste for Cement: X-ray Diffraction, Spectroscopic and Mechanical Investigations

In the production of cement, raw materials can be partially substituted by regenerable waste provided from glasses, construction and demolition waste in order to reduce the environmental problem and burden of landfills. In this study, limestone–silicate composites were synthesized using starting materials such as glass waste and lime, brick, autoclaved aerated concrete (ACC), mortar or plaster waste. The structure and mechanical properties of the nano-composite materials have been studied. The mean CaCO3 crystallite sizes are higher for composites containing ACC and brick than for doping with lime, mortar and plaster. Cement-based materials are formed by replacing 2.5% of the Portland cement with limestone–silicate composites. The results indicate new possibilities for introducing 2.5%of composites in cement paste because they promote the formation of the C-S-H network, which provides strength and long stability for the cement paste. The influence of varied types of mix composites in the expired cement on the initial cracking strain and stress, tensile strength and compressive strength were investigated. The compressive strength values of composite-expired cement specimens are situated between 11.8 and 15.7 MPa, respectively, which reflect an increase from 22.9 up to 63.54% over the compressive strength of expired cement matrix.

Application of Aggregates from Construction and Demolition Wastes in Concrete: Review

In the current century, urbanization and the development of the construction industry have led to the generation of construction and demolition waste (CDW), imposing pressure on ecology and the environment. This has attracted the attention of industry personnel and researchers. This work discusses the current research on recycled coarse or fine aggregate, mainly focusing on the physical, mechanical and durability properties of sustainable concrete with recycled coarse or fine aggregate. Furthermore, it also summarizes CDW recycling and classification in major countries, the production processes of recycled aggregate, and the physical properties. This review will provide a reference for the application of concrete with recycled coarse or fine aggregate. Moreover, this review notes that replacing natural aggregates with both coarse and fine recycled aggregates awaits further experimental exploration.

Phase formation and carbonation impact on the strength of alkali-activated demolition waste with calcium compounds

The present study evaluates the impact of calcium compounds on the reaction kinetics of alkali-activated construction demolition waste. Two materials, concrete and brick demolition waste, were milled to powders and supplemented with either carbonated cement stone or freshly ground cement stone. The mixed solids were further subjected to alkaline activation using a sodium silicate solution. X-ray diffraction, isothermal conduction calorimetry, thermogravimetric analysis, scanning electron microscopy and compressive strength tests were employed to understand the interaction of the reactants. The results indicate that cubes prepared from freshly ground cement stone exhibited higher compressive strength of around 18 MPa than those from carbonated cement stone with a maximum of 7 MPa. This superior strength was approved by subsequent analysis methods. A more significant reaction was observed in the material containing freshly ground cement stone, resulting in increased strength within the system. The presence of portlandite in freshly ground cement stone facilitated the initial formation of calcium silicate hydrate phases.

Effect of incorporating biomass bottom ash and construction and demolition waste powder on the physical-mechanical properties and micro-structure of ternary-blended mortars

Biomass bottom ash (BBA) and construction and demolition waste (CDW) are two waste types whose recycling requires immediate actions due to the high quantities in which they are generated worldwide. Since the cement industry is currently facing a real challenge on a global scale due to the environmental cost implicit in cement production, the objective of this study was to evaluate the possibility of reusing those wastes as an addition in ternary-blended eco-cements with a lower impact than common cements. To achieve this, the chemical, physical, mechanical and micro-structural characterisation of the pastes and mortars manufactured with substitution percentages of 10–40% and 1:1 ratio was carried out. The results showed that the mixture of biomass bottom ash and construction and demolition waste powder in the same proportion had the capacity to fix lime and that the new ternary-blended eco-cements made with 20%, 30% and 40% substitution can be classified as CEM IV/A or CEM IV/B pozzolanic cements pursuant to the EN 197–1 standard. All of the new eco-cements also met the regulatory requirements for initial setting time and soundness, with no workability problems recorded. Finally, the mortars made with cement substitutions up to 20% developed similar or greater compressive strength and presented lower porosity at a later age than the reference mortar, making them suitable for use in construction.

Species selection as a key factor in the afforestation of coastal salt-affected lands: Insights from pot and field experiments

Soil salinization is a significant global issue that leads to land degradation and loss of ecological function. In coastal areas, salinization hampers vegetation growth, and forestation efforts can accelerate the recovery of ecological functions and enhance resilience to extreme climates. However, the salinity tolerance of tree species varies due to complex biological factors, and results between lab/greenhouse and field studies are often inconsistent. Moreover, in salinized areas affected by extreme climatic and human impacts, afforestation with indigenous species may face adaptability challenges. Therefore, it is crucial to select appropriate cross-species salinity tolerance indicators that have been validated in the field to enhance the success of afforestation and reforestation efforts. This study focuses on five native coastal tree species in Taiwan, conducting afforestation experiments on salt-affected soils mixed with construction and demolition waste. It integrates short-term controlled experiments with potted seedlings and long-term field observations to establish growth performance and physiological and biochemical parameters indicative of salinity tolerance. Results showed that Heritiera littoralis Dryand. exhibited the highest salinity tolerance, accumulating significant leaf proline under increased salinity. Conversely, Melia azedarach Linn. had the lowest tolerance, evidenced by complete defoliation and reduced biomass under salt stress. Generally, the field growth performance of these species aligns with the results of short-term pot experiments. Leaf malondialdehyde content from pot experiments proved to be a reliable cross-species salinity tolerance indicator, correlating negatively with field relative height growth and survival rates. Additionally, parameters related to the photosynthetic system or water status, measured using portable devices, also moderately indicated field survival, aiding in identifying potential salt-tolerant tree species. This study underscores the pivotal role of species selection in afforestation success, demonstrating that small-scale, short-term salinity control experiments coupled with appropriate assessment tools can effectively identify species suitable for highly saline and degraded environments. This approach not only increases the success of afforestation but also conserves resources needed for field replanting and maintenance, supporting sustainable development goals.

Environmental impacts and performance assessment of recycled fine aggregate concrete.

Natural disasters and human demolition create vast amounts of construction and demolition waste (CDW), with a substantial portion being concrete waste. Managing this concrete waste is a daunting challenge for developing countries with limited resources, aiming to mitigate its harmful environmental effects. Therefore, the proposed approach involves using recycled fine aggregates (RFA) instead of fresh fine aggregates (FFA) in concrete, which aligns closely with achieving sustainable environmental objectives. Extensive laboratory tests were conducted to assess the effects of adding RFA to concrete. The influence of 0 to 100% RFA replacement and different curing times was investigated on compressive strength, tensile strength, resistance against chloride ion penetration and chemicals exposure, and quality of aggregates. So, around 30%, 35%, 20%, and 79% reductions in compression strength, tensile strength, modulus of elasticity, and workability were estimated when 100% RFA was used in recycled aggregate concrete (RAC). However, according to results analyses, the performance of RAC is reliable up to 50% of RFA in proposed conditions and mix design. In addition, major environmental impacts such as global warming potential, aquatic eutrophication, and aquatic acidification were reduced by 47%, 40%, and 18%, respectively, for concrete having 50% RFA than concrete having 100% FFA.

From Construction to Contamination: Examining Soil Quality Degradation Associated with Construction and Demolition Waste in an Indian Urban Area

From Construction to Contamination: Examining Soil Quality Degradation Associated with Construction and Demolition Waste in an Indian Urban Area

Analysis of Multi-Stakeholder Behavioral Strategies in the Construction and Demolition Waste Recycling Industry through an Evolutionary Game Theory

Construction and demolition waste (C&DW) recycling products have drawn worldwide attention over the past few decades. There is a general agreement among researchers that C&DW recycling is an important means for curbing the deterioration of the environment. Previous papers mainly focused on the decision-making behavior of dual stakeholders or tripartite stakeholders, as well as the lack of cooperation among multiple stakeholders. This study explored a dynamic evolutionary game model with three different parameter conditions to research the decision-making behaviors and stable strategies of the multi-stakeholders involved in the C&DW recycling product industry, including government departments and some enterprises. This research also investigated how the government’s supervision costs, penalties applied to enterprises, and resource taxes affect the dynamic evolution process of C&DW recycling. This research conducted numerical simulations using Python to analyze stakeholders’ behavioral evolutionarily stable strategy (ESS) and the sensitivity to main factors in each stage of the C&DW recycling process to accelerate the development of construction waste resource utilization. Based on the results of the evolutionary game, this paper proposed that the roles of multi-stakeholders are different at different stages of industry development, and that supervision costs, penalties, and resource tax have their own impacts on the C&DW recycling product industry. The paper suggests a range of discussions and simulation studies to highlight the significance of the government’s refined and moderate adjustments to the regulatory incentive system and the level of government regulation and involvement at different stages of the process. These adjustments are aimed at promoting the sustainable recycling and utilization of construction and demolition waste (C&DW) products within some countries’ construction industry.

Utilizing Waste Materials to Enhance Crop Production: A Review

Waste management is a crucial aspect of modern societies, encompassing various activities to ensure the safe and effective disposal of waste materials. It can be classified as hazardous waste, electronic trash (e-waste), industrial waste, and municipal solid waste (MSW). Sustainable waste management practices aim to reduce environmental impact while protecting public health. Urbanization leads to increased residential water consumption, however reusing wastewater for non-potable applications like agriculture can be cost-effective. The overall costs of delivering wastewater for agricultural reuse, including treatment, storage, and transportation, are less the total costs of safe environmental disposal alternatives. Drainage may also be a source of macronutrients (nitrogen, phosphorus, and potassium), which reduces the cost of wastewater for agricultural reuse. The adoption of these principles could lead to a 48% reduction in global greenhouse gas emissions by 2030. The management of hazardous waste, including toxic, flammable, corrosive, or reactive materials, is also a significant concern. In order to safeguard public health and stop the spread of infectious illnesses, animal manure management is crucial. The global generation of construction and demolition waste is expected to double by 2025, with the majority generated in Asia. Sustainable waste management practices are necessary to ensure public health and the environment.

Synergistic effects of recycled demolition waste and GGBS-FA based geopolymers on the mechanical properties and stabilization mechanism of high plasticity clay

Recycled demolition waste (RDW) and ground granulated blast furnace slag-fly ash-based geopolymer (GFG) are promising materials for treating high-plasticity clay (CH) in highway subgrades. However, the underlying synergistic stabilization mechanisms remain unclear. To elucidate the fundamental mechanisms governing post-treatment soil stabilization, a multi-scale laboratory investigation was undertaken. This investigation encompassed the evaluation of mechanical properties (compaction, California bearing ratio (CBR), and unconfined compressive strength (UCS)) to quantify the enhanced performance of the treated soil. Additionally, microstructural and mineralogical characterization was performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and atomic force microscopy (AFM) to elucidate the microscopic mechanisms responsible for this improvement. The results indicated that the addition of RDW led to a reduction in the optimum moisture content (OMC) while increasing the maximum dry density (MDD) of CH. Moreover, upon incorporating RDW-GFG, the mechanical properties of the cured soil exhibited significant improvement. Specifically, the addition of 25% RDW to CH resulted in a 184% increase in CBR and effective improvement in water stability (immersion swelling percentage is reduced). Furthermore, when 25% RDW and 15% GFG were added to CH, the UCS has increased significantly by 8 times. The addition of RDW effectively enhanced the particle size distribution, compacted the soil, thus increased the shear strength. The results from XRD and SEM analyses revealed that the inclusion of GFG could generate geopolymer cementitious bonding network in the soil matrix. These materials facilitated bonding between CH particles and RDW, filling the pores and densifying the overall structure, thus increasing its strength. The synergy of RDW-GFG substantially improved the highly plastic soil through physicochemical actions, markedly elevating both its strength and water stability. Consequently, the outcomes of this experimental study offer valuable insights for road engineering applications.

Compressive Strength, Permeability, and Abrasion Resistance of Pervious Concrete Incorporating Recycled Aggregate

Extensive use of cement in the construction industry increases CO2 emissions and has a negative impact on the environment. In this work, recycled coarse aggregate (RCA) from construction and demolition wastes (C&DW) was used to fabricate sustainable pervious concrete (PC). In order to mitigate the environmental hazards of excess cement waste and to improve the engineering properties of PC, silica fume (SF) and ground granulated blast-furnace slag (GGBS) were added. The effects of SF and GGBS on the compressive strength, permeability coefficient, porosity, and abrasion resistance of recycled aggregate pervious concrete (RAPC) were investigated. The results show that the incorporation of GGBS and SF effectively improves the compressive strength of RAPC but reduces the permeability coefficient and porosity. Moreover, due to the filling effect and pozzolanic activity, the incorporation of GGBS and SF significantly enhances the abrasion resistance of RAPC. Furthermore, the relationships between the compressive strength, permeability coefficient, porosity, and abrasion resistance of RAPC are clarified. The optimum replacement is achieved when the SF content is 7%, and the GGBS content is 20%, respectively, which results in the highest compressive strength (28.9 MPa) and the lowest permeability coefficient (1.2 mm/s) at 28 days, and the lowest mass loss rate (12.1%) after the Cantabro abrasion test.

Performance of foam concrete developed from construction and demolition waste

Unconscious industrialization, urbanization and consumption of natural resources pose a serious threat to the environment. The threat can be reduced by upcycling construction and demolition waste (CDW) in the production of foam concrete, which is a special type of concrete used especially for thermal insulation purposes. This study aims to use of CDW as a source of fine aggregate (0–4 mm) in the production of foam concrete mixtures. A series of mixtures with target density values between 500 and 900 kg/m3 were designed with various recycled aggregate and foam contents to investigate the physical, mechanical and thermal properties of the mixtures. Findings of the study reveal that mixtures with an elevated foam content possess a greater number of larger pores, which, as observed through microscopy, form interconnected structures that are porous. On the other hand, adding more fine recycled material (FRM) makes the matrix denser, which reduces the overall porosity and increases the packing density. In contrast to increased content of FRM, correlation coefficient of (−0.77) reveal a more powerful inverse relationship between risen level of foam content (−0.67) and the reduction ratio of fresh-to-dry density and the increase in compressive strength from 7 to 28 days. It is also known that mixes with more foam have better thermal insulation because they trap more air, while mixes with more FRM show an increase in thermal conductivity. The sensitivity analysis showed that changes in thermal conductivity are almost three times as sensitive for FRM content, which means they have a bigger effect than changes in foam content. Employing the Taguchi method, (R_0.714) emerges as the most efficient tested combination indicative of superior overall performance. Notably, the Taguchi method predicts the untested combination (0.100-F/C ratio + 0.714-R/C ratio) as potentially more efficient, suggesting avenues for further exploration and optimization. This study furnishes valuable insights into sustainable construction practices by reutilizing CDW in foam concrete production, thereby contributing to both environmental conservation and enhanced structural outcomes.

Mechanical and Thermomechanical Evaluation of Geopolymeric Concrete Derived from Demolition Waste and its Comparison with Conventional Portland Cement Concrete

Mechanical and Thermomechanical Evaluation of Geopolymeric Concrete Derived from Demolition Waste and its Comparison with Conventional Portland Cement Concrete

Enhancing the physical performance of concrete containing construction and demolition waste against the effects of accelerated carbonation and chloride ingression

Enhancing the physical performance of concrete containing construction and demolition waste against the effects of accelerated carbonation and chloride ingression

Pull-out response of a geogrid buried in recycled sands

Recycled construction and demolition waste (RCDW) has demonstrated geotechnical properties that encourage it to be used in reinforced soil structures (RSS) with geosynthetics. However, the interaction between RCDW and reinforcements needs to be better understood, given its importance for design. This paper presents a qualitative study on the interaction between geogrid and recycled sands by means of pull-out tests performed on small equipment. Tests with the same degree of compaction and a geogrid buried in different types of recycled and natural sands (for comparison purposes) were performed. The characterisation of the materials was carried out in the laboratory and the variability of their geotechnical properties was evaluated. In addition, fill material moisture content was investigated as another potential factor influencing soil-geogrid interface shear. The results of the pull-out tests demonstrated the specific influences of the factors investigated. The comparative study showed that recycled sands can be suitable materials to be used as backfill in geosynthetic reinforced soil structures, meeting physical, mechanical and environmental requirements for this kind of work.

Combined application of CDWs as precursors and aggregates in geopolymer composites: A comprehensive rheological analysis

The study of rheological characterization of construction and demolition waste (CDW)-based geopolymeric materials has gained interest due to digital innovation in construction and the increased focus on sustainable materials. Understanding the rheological behavior of these materials is essential due to their rapid geopolymeric reaction kinetics and viscosity behavior. This study investigated the impact of various CDW-based fine recycled aggregates, including crushed concrete aggregates (CRC), crushed ceramic-tile aggregates (CTA), and crushed brick aggregates (CBA), on the rheological behavior of geopolymer mortars (GPMs). Natural sand (NSA) was utilized as a reference for comparison purposes. In addition to CDW-aggregates, the GPMs were also made from optimized CDW-based precursors of brick waste powder (BP), ceramic-tile waste powder (TP), or concrete waste powder (CP). As a result, twelve different GPMs were considered, each containing 100 % individual CRC, CTA, and CBA fine aggregates, blended with BP, TP, and CP precursors. The study evaluated the relationship between the design variable of SiO2/Al2O3 molar ratio as well as the packing densities (PD) of GPM systems and their rheological characteristics, such as flow, apparent and plastic viscosity, yield and shear stresses, thixotropy and shear strains employing the compressible packing method. The results indicate that all GPMs possess shear-thinning or pseudoplastic characteristics. Enhanced SiO2/Al2O3 molar ratio generally resulted in increased rheological parameters. However, using TP as a precursor and CBA as fine aggregates in GPM matrices led to significant enhancement in rheological parameters due to the higher specific surface area of TP and the greater irregularity, convexity, and absorption capacity of CBA particles. Notably, although the enhanced non-colloidal frictional interactions and colloidal flocculation of CRC, CTA, and CBA resulted in reduced flow tendency of GPMs, they have been found to improve the thixotropy during the initial geopolymeric gelation stage.

Introducing a Novel Concept for an Integrated Demolition Waste Recycling Center and the Establishment of a Stakeholder Network: A Case Study from Germany

Using recycled aggregates has many positive environmental impacts because of the conservation of natural resources and minimization of waste. The use of recycled aggregates in downcycling processes is already common in Germany, whereas utilizing them to produce high-quality recycled concrete is rarely applied in practice. The reasons behind this lag have been investigated based on surveys and interviews with stakeholders. Miscommunication and missing information were identified in all stakeholder groups. Therefore, establishing a robust network and facilitating knowledge transfer by specifying the demand for recycled aggregates in the case study region have been considered as prerequisites. Therefore, the paper presents a novel concept of a stakeholder network for an integrated construction and demolition waste center. The conceptualization integrates the recycling companies and construction product manufacturers in one venue with research, service, and educational divisions. The design of the facilities is based on calculations regarding future construction activities and the demand for concrete production. The proposed concept aims to supply the region in the west of Germany with high-quality recycled products while also establishing a robust network that offers benefits in terms of logistical optimization and knowledge transfer.

Prediction of properties of recycled aggregate concrete using machine learning models: A critical review

Recycled aggregate concrete (RAC) not only alleviates the shortage of natural aggregates but also promotes the recycling of construction and demolition waste, contributing to sustainable development. Traditional empirical and statistical formulas have limited applicability and perform poorly when dealing with complex relationships. Therefore, machine learning has been widely used to predict the performance of RAC. In this paper, an overview is provided of the current research examining the impact of various parameters on the workability, mechanical properties and durability of RAC. The discussion and evaluation are focused on the applicability, accuracy, hyper-parameter selection, and input variables of machine learning algorithms that are employed to predict the performance of RAC. The advantages and disadvantages of different algorithms are compared, and the practical suggestions are given based on their performance. Additionally, the limitations of current research are discussed, and the perspectives for the prediction of RAC's performance based on the machine learning models are proposed.