Recycling Of Demolition Waste Research Articles

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.

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.

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.

Mechanical and Durability Characterization of Hybrid Recycled Aggregate Concrete.

The recycling of construction and demolition waste (CDW) for the extraction of recycled concrete aggregates (RCAs) to be used to produce recycled aggregate concrete (RAC) is widely acknowledged internationally. However, CDW not only contains concrete debris but may also contain burnt clay bricks. The recycling of such CDW without the segregation of different components would result in recycled aggregates having different proportions of concrete and brick aggregates. The utilization of these aggregates in concrete requires a detailed investigation of their mechanical and durability properties. In this regard, the present study focused on investigating the mechanical and durability properties of hybrid recycled aggregate concrete (HRAC) made by the 100% replacing of natural aggregates with recycled brick (RBAs) and RCA in hybrid form. The partial replacement of cement with fly ash was also considered to reduce the corban footprint of concrete. An extensive experimental program was designed and carried out in two phases. In the first phase, a total of 48 concrete mixes containing coarse RBA and RCA in mono and hybrid forms were prepared and tested for their compressive strength. The test results indicated that the compressive strength of HRAC is greatly affected by the proportion of coarse RBA and RCA. In the second phase, based on the results of the first phase, eight concrete mixes with the most critical proportions of RBA and RCA in hybrid form were selected to evaluate their mechanical and durability performance. In addition, four mixes with natural aggregates were also prepared for comparison purposes. To evaluate the mechanical properties of the concrete mixes, compressive strength and modulus of rupture (MOR) tests were performed, while for the evaluation of durability properties, water absorption and behavior after exposure to aggressive conditions of acidic and brine solutions were studied. The results revealed that a 20% replacement of cement with fly ash resulted in acceptable mechanical and durability properties of HRAC intended to be used for making concrete bricks or pavers.

Study on the performance of ternary blended cement with calcined clay and recycled concrete powder

Recycled concrete powder (RCP) has a large amount of calcium carbonate, which suggests that it can be used to make limestone - calcined clay (CC) cement (LC3) system by replacing limestone powder. So that it can promote the recycling of construction demolition waste and reduce the requirement of the natural resource for LC3. In this study, the fresh and hardened properties of CC-RCP cement system were comprehensively characterized by varying the CC/RCP ratio and dosage, including rheological, mechanical properties, hydration products and pore structure. The results indicate that the addition of CC prolong the setting time, but the effect could be mitigated by the recombination of RCP. By comparing with RCP, CC had a less obvious effect on increasing viscosity, but it could improve the shear thickening behavior of paste. In the case of less total content of CC and RCP, a ratio of 1:1 CC/RCP was better for the development of long-term strength. Whereas, with the increasing of substitution, the mixtures with CC alone or blending with RCP in a 2:1 ratio achieved higher strength. The incorporating of CC and RCP could make the conversion of C4AH13 into hemicarboaluminate (Hc) and monocarboaluminate (Mc), and it resulted in a denser structure with more medium capillary pores and gel pores than that mixtures with CC only.

Investigating the Determinants of Construction Stakeholders’ Intention to Use Construction and Demolition Waste Recycling Products Based on the S-O-R Model in China

In China, the annual generation of construction and demolition waste (CDW) has been steadily increasing, accompanied by a generally low recycling rate. To promote sustainable development, there is an urgent need to enhance the recycling of CDW. This paper aims to investigate the determinants of construction stakeholders’ intention to use CDW recycling products in China. The stimulus–organism–response (S-O-R) model, integrating the technological–organizational–environmental (TOE) framework, personal perceptions, personal traits, and the intention to use, was chosen as our theoretical model. Through an analysis of 272 valid questionnaires, the partial least squares structural equation modeling (PLS-SEM) was utilized to evaluate the model and test the proposed hypotheses. The results indicated that personal traits are the most influential factor shaping construction stakeholders’ intention to use, followed by personal perceptions, while external stimuli exert no direct significant impact on the intention to use. Nevertheless, personal traits and personal perceptions play a significant mediating role in the relationship between external stimuli and the intention to use, forming a noteworthy serial chain mediation. The research findings imply that in China, bolstering personal traits plays a critical role in guiding and promoting the intention to use CDW recycling products.

Sustainable urban development: Evaluating the potential of mineral-based construction and demolition waste recycling in emerging economies

Widespread illegal disposal of surging construction and demolition waste (CDW) is a prominent threat to recycling, leading to resource wastage and environmental issues. The lack of data is a major barrier to designing an effective waste management system in emerging economies. Employing a mixed-method approach, a cross-sectional case study was conducted on an Indian city to assess the existing system and investigate the root causes of low recycling rates and limited demand for recycled materials. The study finds that (a) illegal disposal is prevalent due to the "end-of-pipe" approach of the waste management system, (b) policy enforcement on waste generators is weak, (c) low-rise residential buildings are the major contributor of waste, (d) low demand for recycled material is due to lack of awareness, marketing, incentives, and high costs, (e) transportation costs are 50 % higher than the recycled material cost, and (f) lack of segregation leading to the production of low-value materials. All these factors make recycling unattractive and the circular economy (CE) unfeasible. Stakeholder awareness, a centralized trading platform, and integrated waste management systems are essential to promote recycling and advance SDGs 9, 11, and 12, focusing on industry, sustainable cities, and responsible consumption and production.

Köpük Beton Üretiminde İnşaat Yıkıntı Atığı İnce Agregası Kullanımı ve Optimum Su/Çimento Oranının Belirlenmesi

İnşaat sektöründe hammadde temini doğal kaynaklarımız hızlı azalmasına veya tahrip edilmesine neden olmaktadır. Doğal kaynakların azalmasını veya tahrip edilmesini azaltmak için inşaat yıkıntı atıklarının geri kazanılması, hammaddeye ihtiyacını ve aynı zamanda çevresel kirliliğini de azaltılacaktır. Bu çalışmada inşaat yıkıntı atığı ince (kum) agrega ile köpük beton üretile bilirliği araştırılmıştır. Karışımlarda agrega olarak 4 mm elekten geçen inşaat yıkıntı atığı kullanılarak 5 farklı su/çimento oranı ile köpük beton üretilmiştir. Üretilen köpük beton numunelerinin birim hacim ağırlıkları, basınç dayanımları, su emme oranı, ultra ses geçiş hızı ve ısıl iletkenlik katsayıları gibi özellikleri incelenmiştir. Bu özeliklerden en uygun olanlar S/Ç oranı 0,45 olan karışım tasarımı vermiştir.

The effect of incentive policies on the diffusion of construction and demolition waste recycling: A government perspective.

Construction and demolition (C&D) waste recycling plays a significant role in waste reduction and carbon reduction, which is critical for sustainable development. However, due to various limitations such as financial problems, C&D waste recycling industry is not well developed in developing countries. To address this problem, this study combines complex network theory and evolutionary game theory to analyse the diffusion of C&D waste recycling behaviour among enterprises under governmental incentive policies within a complex network context. The results demonstrate that the size of the network has limited effects on behaviour diffusion in Watts-Strogatz small-world network. Additionally, the study highlights the clear impact of governmental incentive probability, initial rate and connection degree on the diffusion path. By quantitatively investigating the effects of incentive tools, this study contributes to the knowledge of C&D waste management and provides valuable implications for stakeholders seeking to promote the diffusion of C&D waste recycling.

Effect of construction demolition waste as fine aggregate and NaOH molarity on strength and fracture parameters of slag based geopolymer mortars

To achieve sustainable development, it is imperative that we find ways to manage sand resources wisely. One approach to mitigate the impact of sand extraction is the recycling of construction demolition waste (CDW) and its reuse in construction activities. This research paper primarily delves into the investigation of the strength and fracture properties of slag-based geopolymer mortar (SGPM) while varying the molarities of sodium hydroxide and altering the proportions of recycled fine aggregate (RFA) sourced from CDW. Two distinct binder-to-fine aggregate mix ratios, namely 1:1 and 1:3, were taken into consideration. The study employed sodium hydroxide (NaOH) and sodium silicate solutions as alkali-activators. Various NaOH concentrations of 2 M, 4 M, 6 M, 8 M, and 10 M were utilized, and RFA was employed to replace natural fine aggregate at levels of 10%, 20%, 30%, and 40%. The workability of SGPM was assessed in terms of flowability, while the compressive and flexural strengths were measured following a 28-day curing period. Moreover, fracture parameters, including load–deflection behavior, peak load, deflection at peak load, and fracture energy, were investigated through a three-point bending (TPB) test conducted on notched beams. The test results revealed that the flowability, expressed as a percentage of flow, decreased as the molarity of NaOH and the percentage of RFA increased. Conversely, the compressive and flexural strength values exhibited an upward trend as the NaOH concentration increased from 2 to 10 M. A substantial improvement in both compressive and flexural strengths was observed at a 10 M NaOH solution, with increases of 20.73% and 10.63% in the 1:1 mix ratio and 18.94% and 10.46% in the 1:3 mix ratio. However, these values decreased with an increase in the percentage of RFA, ranging from 10 to 40%. Notably, specimens containing 8 M and 10 M NaOH concentrations demonstrated a more brittle behavior compared to specimens with other NaOH concentrations. Moreover, a decline in fracture energies was evident as the molarity of NaOH and the percentage of RFA increased. These findings highlight effect of NaOH concentration, RFA content on mechanical and fracture properties of SGPM, providing valuable insights for sustainable construction materials.

Pricing Decisions in Construction and Demolition Waste Recycling Supply Chains under Carbon Tax Scenarios

Pricing decisions for construction and demolition waste recycling are severely hampered by consumer uncertainty in assessing the value of recycled building materials. This paper uses a construction and demolition waste (CDW) recycling utilization model that consists of a building materials manufacturer and a building materials remanufacturer and compares both the prices and the profits under different carbon tax scenarios, i.e., consumer risk-averse and risk-neutral scenarios. The main conclusions are as follows. (1) The optimal price of traditional products is always negatively correlated with consumer risk aversion. Unlike traditional products, the optimal price of recycled building materials is negatively related to the degree of consumer risk aversion in the case of a low carbon tax; the opposite conclusion is obtained in the case of a high carbon tax. (2) When the abatement cost coefficient is below the threshold and the carbon tax is low, the profits of the building materials manufacturer and remanufacturer show a U-shaped trend with consumer risk aversion; in the case of a high carbon tax, the profits of the two enterprises are positively correlated with consumer risk aversion. In addition, when the abatement cost coefficient is above the threshold, there is an interval in which the profits of the building materials manufacturer are positively correlated with consumer risk aversion in the case in which the carbon tax satisfies this interval. In all the other cases, there is a U-shaped trend in profits and consumer risk aversion levels for both the building materials manufacturer and the remanufacturer.

Preparation of recycled sand from WRSG and compressive and flexural behavior of recycled aggregate concrete

The use of both recycled coarse aggregates (RCAs) and recycled sand (RS) derived from weathered residual soil of granite (WRSG) into concrete has the potential to greatly enhance the recycling of construction and demolition waste. However, the characterization of RS from WRSG and the compressive and flexural performance in fresh concrete containing RCAs and RS have not been thoroughly investigated. In this study, clay content, fineness modulus, chemical compositions, mineral compositions, and pore structure of RS from WRSG were tested. On this basis, the optimized preparation parameters of RS were suggested. The compressive behavior, flexural behavior, and cement hydration degree of recycled aggregate concrete (RAC) simultaneously containing RS and RCAs were investigated comprehensively. A stereological model was proposed to explain the results related to cement hydration. The results showed that: (a) the optimized preparation could substantially lower the clay content of RS; (b) RS was more porous than natural sand (NS), resulting in a higher water absorption during mixing; (c) the compressive strength of concrete containing RS developed faster than the concrete with NS; (d) at day 90, the compressive and flexural strength of the concrete containing RS were not less than those of the concrete with NS; and (e) RS was shown to have a greater influence on the hydration degree of cement paste than RCAs, due to RS significantly reducing the average value of inter-aggregate spacing in concrete, making the cement paste more susceptible to the internal curing effect induced by the water in aggregate pores.

Water content estimation of recycled building materials based on near-infrared spectroscopy

Recycling of construction and demolition waste (CDW) is one key component of the circular economy. Reusing construction materials opens the opportunity to preserve finite natural resources and their corresponding landscapes, and also reduces the emission of greenhouse gases.Unfortunately, recycling of CDW is challenging when the new product ought to be used on the same quality level as the demolished one and down-cycling should be avoided. Therefore, the CDW needs to be classified and impurities must be removed. The water content quantification of the recycled aggregates is important because the amount of existing water needs to be known, e.g., when calculating a mixture for recycling concrete. New developments in the classification and the sorting of CDW make use of the information from the spectral range in the visual and infrared region. Therefore, the approach of this study is to examine whether this information can be used to estimate the water content of various CDW materials. Based on reflection measurements in the near-infrared range between 1000nm and 2300nm a mathematical relationship between the spectral measurements and the water content is established. Three estimates for the water content are set up. The mean absorption, the water index, and the absorption difference are later tested on CDW material samples covering concrete, autoclaved aerated concrete, lightweight concrete, brick, roof tile, calcium silicate brick and gypsum.

基于环境教育的建筑固废再生利用实践研究

基于环境教育的建筑固废再生利用实践研究

Experimental and numerical evaluations of the shear performance of recycled aggregate RC beams strengthened using CFRP sheets

Conserving the ecosystems of the globe, protecting natural resources, and improving environmental conditions can all be achieved by considering sustainability in the construction industry. Recycling of building and demolition waste is one of the key approaches being investigated to accomplish this target. Twelve reinforced concrete (RC) beams were constructed for the current study in order to analyze the shear behavior of recycled aggregate concrete (RAC) beams externally strengthened with carbon fiber reinforced polymer (CFRP) sheets. The main goal of the experimental matrix was to investigate the effect of the recycled aggregate ratio on the shear response of RAC, where three recycled coarse aggregate ratios of 20%, 60%, and 100% were suggested. Additionally, the effects of incorporating two or four CFRP strengthening layers on the ultimate load, failure pattern, load-deflection responses, and stiffness of RAC beams were also investigated. Results revealed that, when different ratios of recycled aggregate estimated at 20%, 60%, and 100% were substituted for natural aggregates, the compressive strength decreased by 4.3%, 24.2%, and 40.0%, respectively, compared to natural aggregate concrete. Moreover, the RC beam that was cast utilizing 20% recycled aggregates and strengthened with four CFRP sheets exhibited the highest ultimate load among all the tested RAC beams of 84.8 kN, which was 22.9% higher than the un-strengthened specimen totally cast with natural aggregate. Furthermore, a three-dimensional (3D) non-linear finite element model (FEM) was constructed using the ABAQUS program in order to compare the effects of employing continuous CFRP sheets for the whole critical shear span length to intermittent strips that had been experimentally tested.

Assessing the Effects of Refuse-Derived Fuel (RDF) Incorporation on the Extrusion and Drying Behavior of Brick Mixtures

This study explores the potential benefits of incorporating Recycled Demolition Waste (RDF) as an additive in ceramic mass for the brick industry, with a focus on applications such as thermoblocks. The research underscores the significance of sustainable waste management practices and environmental conservation by diverting waste from landfills. RDF, exhibiting combustion properties above 550 °C, emerges as a valuable candidate for enhancing clay-based materials, particularly in the brick production process where firing temperatures exceed 850 °C. Conducted in two phases, the research initially concentrated on RDF preparation, RDF integration with clay materials, and its influence on extrusion and drying phases. Employing innovative techniques involving brick and tile industry machinery coupled with sand incorporation yielded promising results. The grounding of RDF particles to less than 1 mm not only facilitated the mixing process but also ensured stable grinding temperatures within the hammer mill, reducing operational costs. During extrusion, challenges associated with unprocessed RDF material were addressed by utilizing ground RDF, leading to a more efficient and cost-effective process with enhanced plasticity and reduced water requirements. Practical implications for brick plant operations were identified, promoting resource and energy savings. Drying behavior analysis revealed the positive impact of RDF integration, showcasing reduced sensitivity, decreased drying linear shrinkage, and improved density properties. RDF’s role as an inert additive resulted in a 5% reduction in density, enhancing porosity and thermal insulation properties, particularly in thermoblock applications. In the brick industry, where durability, thermal performance, and cost-efficiency are paramount, this study emphasizes the potential benefits of incorporating RDF into clay-based materials. While further research is needed to address the firing procedure of RDF as a brick mass additive, the initial findings underscore the promise of this approach for sustainable and environmentally responsible brick production. This study contributes to the literature by shedding light on the advantages and challenges of integrating RDF into clay-based products, supporting sustainability and waste reduction in construction and manufacturing. The findings provide valuable insights into the performance and feasibility of these mixtures, offering crucial information for industries striving to adopt eco-conscious production methods. This article not only outlines the applied methodology and experimental setup but also presents results related to the behavior of RDF-inclusive clay block mixtures in the production environment. Anticipated to exert considerable influence on future practices and policies, this research contributes to the growing body of knowledge concerning eco-friendly and sustainable manufacturing processes.

Recycling of construction waste as an innovative direction of the program of post‐war reconstruction of destroyed cities

AbstractThere are officially more than 5.5 thousand dumps in Ukraine, landfills with a total area of more than 9,000 hectares, and there are more than 2000 illegal dumps. The issue of waste disposal (garbage) has always been very acute, not only during the war, a significant part of this waste is construction waste. During the hostilities, many Ukrainian cities and settlements suffered various types of destruction, and some suffered almost the greatest destruction of various objects of urban infrastructure. All this contributed to the emergence of a large amount of demolition waste. The article analyzes the current state of management of demolition waste in Ukraine. The goals and objectives of recycling construction waste in the conditions of post‐war reconstruction of destroyed urban areas are formulated. The results of theoretical studies of methods of utilization of demolition waste by their reuse in construction are given. The preferred types of construction waste in case of destruction of buildings include clogged soil, asphalt, stone materials, brick, concrete and reinforced concrete, wood, ceramic tiles, etc. Each of these types of demolition waste needs a separate recycling. The article gives the classification and structure of demolition waste and defines, what operations to handle it are required. The requirements for the arrangement of temporary storage of construction waste are formulated. Prospects for the development of recycling of demolition waste in Ukraine are considered. The ways of reuse in construction of demolition waste components are proposed. Recommendations of measures of step‐by‐step management of construction waste in Ukraine were provided.

Barriers to circular economy practices during construction and demolition waste management in an emerging economy

The construction industry requires significant quantities of material and energy resources, which are either recycled or disposed as waste after demolition. Circular Economy (CE) facilitates the benefits of reuse and recycling of Construction and Demolition Waste (CDW) and promotes the industry in cradle-to-cradle or “Resolve” paradigms. However, in emerging economies, the industry merely achieves to harness a negligible amount of the CDW's intrinsic monetary benefit and sustainability, due to multiple barriers to circular practices. This study examines barriers that obstruct the incorporation of circular economy practices in the Indian construction industry. The study uses Relative Importance Index (RII), Factor Analysis, and Regression analysis to arrive at a list of macro-environmental barriers to the use of CE in CDW. The findings are presented using the PESTEL framework, with Political, Social, and Economic factors being the dominant barriers to the use of CE in CDW in emerging economies. Results from this study point towards the need for better guidelines by regulators for recycling of CDW, incentive schemes, and overall capacity building in emerging economies.

Formulating Geopolymer Mortars through Construction and Demolition Waste (CDW) Recycling: A Comprehensive Case Study

Formulating Geopolymer Mortars through Construction and Demolition Waste (CDW) Recycling: A Comprehensive Case Study