Recycling Of Construction Waste Research Articles

Development of sustainable alkali-activated slag bricks with high content of carbonated recycled concrete fines: Strength, microstructure and environmental benefit

This research presents a novel method of recycling construction waste while capturing CO2 through the formation of mineral carbon. The technology uses carbonated recycled concrete fines (CRCF) as the primary raw material to produce sustainable, high-performance alkali bricks with high replacement rates. Firstly, a general assessment of the physical and chemical properties of CRCF was carried out, which revealed the formation of silica gel encapsulating the surface of CRCF during carbonation. Subsequently, alkali bricks were prepared utilizing CRCF. The study investigated the impact of various mix proportions, water-to-cement ratios, and manufacturing process parameters on brick strength. Additionally, an in-depth analysis of reaction products and brick microstructures was carried out. The results showed that the bricks produced from CRCF were stronger than those from RCF, indicating enhanced reactivity after carbonation. Finally, an analysis demonstrated that utilizing RCF from construction waste can significantly reduce carbon dioxide emissions, thereby mitigating the environmental impact associated with cement production.

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.

Analysis of water migration in an earthen landfill cover with recycled construction waste

In this study, numerical analysis was conducted to investigate the effects of particle sizes on water migration in a three-layer landfill cover system using recycled concrete aggregates (RCAs). This cover system consists of a top fine recycled concrete aggregate (FRC) layer and a middle coarse recycled concrete aggregate (CRC) layer overlying a bottom silty refuse soil layer. Numerical simulations were performed to back analyse a flume model test data and further evaluate the particle size effects of RCAs on the effectiveness of the cover system. With the increase in rainfall duration, surface runoff reduced, while the lateral diversion increased pronouncedly. Nonetheless, no significant percolation is observed through the cover system using RCAs during 100-year extreme rainfall with different durations. Based on the results, the d10 of FRC is recommended to be from 0.2 mm to 0.5 mm.

Crack development and fracture performance of Recycled Powder Engineered Cementitious Composites (ECC): Experimental investigation

In this paper, recycled concrete powder (RCP) and recycled brick powder (RBP), with particle sizes ranging from 10 to 130 μm, are used to completely replace the fine aggregate quartz sand at a ratio of 1:1. On this basis, recycled glass powder (RGP), with a discussed particle sizes range of 38–300 μm, is used to partially substitute the cementitious materials. Polyethylene (PE) fibers are used as the reinforcement in the Engineered Cementitious Composites (ECC). Using the particle size range and substitution rate of RGP as variables, the crack development, crack mouth opening displacement (CMOD), fracture toughness and fracture energy of Recycled glass powder ECC (RGP-ECC) were discussed through a three-point bending experiment on a single-edge notch beam. A relatively comprehensive evaluation was made on the fracture performance and behavior of recycled ECC, and a suitable mix ratio of recycled powder ECC was given. The results show that the addition of various recycled powders will not affect the multi-slit cracking behavior of ECC, and the cracks can still spread densely, giving the specimen greater deformation capacity and CMOD. The total substitution of fine aggregate by RCP and RBP has a positive impact on the fracture toughness KICini, KICun and fracture energy (GF), but the addition of RGP has some minor negative effects. Among the particle size range and substitution rate of RGP, the influence of substitution rate is more obvious, and the fracture performance will show a downward trend after growth as the substitution rate increases. Choosing the appropriate RGP substitution rate and particle size range can maximize the recycling of construction waste while ensuring fracture performance.

Blockchain-driven framework for construction waste recycling and reuse

Conventional management mechanisms for construction waste recycling and reuse (CWRR) often cause considerable information asymmetry, inadequate government supervision, and imperfect incentive mechanisms, resulting in frequent illegal dumping and landfilling of construction waste and relatively low recycling rates. To address these issues, we introduce blockchain technology to CWRR. The design science research methodology was adopted to identify the main steps in functional requirement identification and blockchain framework development for CWRR. To explain how blockchain can improve the CWRR process, a conceptual model for the functional requirements of the proposed framework was constructed using qualitative analysis. A blockchain-driven framework was developed to overcome practical barriers in the CWRR industry. Based on scenario simulation results, the proposed framework had execution and transaction costs of $4.735 and $1.276, respectively, and latency performance at the millisecond level. The results indicate that (1) based on specific problems systematically identified from CWRR practices, the proposed framework can address practical barriers in the CWRR industry more directly; (2) the CWRR industry can use blockchain technology to achieve information sharing, comprehensive government supervision, and effective incentive mechanisms and (3) the blockchain-driven framework has high efficacy and can promote efficient CWRR and high-quality development of CWRR industry chain. This management model is conducive to forming a collaborative CWRR industry chain that can lead to broader adoption of blockchain technology across industries.

Circular economy and waste: a bibliometric analysis of global scientific production

The Circular Economy (CE) has emerged as an alternative to combat the linear production model, which significantly contributes to the environmental impacts faced today, such as depletion of natural resources, energy scarcity, climate change, and loss of biodiversity. Introduced in 1989, CE is a burgeoning research area, highlighting the need for a more in-depth analysis of its development. This research aimed to conduct a bibliometric analysis of publications in CE related to waste, using the Web of Science database. Between 2007 and 2022, the study identified the countries and authors with the highest production, the most cited journals and articles, and thematic analysis through keyword co-occurrence. The research demonstrated the evolution of studies, particularly from 2020 to 2022, revealing Europe as a leader in publications and indicating the need for encouragement in the African continent. Studies on plastic recycling and energy recovery proved to be extensively explored areas, unlike electronic and construction waste recycling, which emerged as promising fields.

Utilizing response surface methodology (RSM) to predict the mechanical characteristics of concrete incorporating treated recycled construction and demolition waste aggregate (CDW) and discarded reverse osmosis (RO) membrane

Utilizing response surface methodology (RSM) to predict the mechanical characteristics of concrete incorporating treated recycled construction and demolition waste aggregate (CDW) and discarded reverse osmosis (RO) membrane

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.

Анализ возможности повторного использования и переработки строительных отходов на этапе создания информационной модели здания

The article discusses the possibility of reusing and recycling construction waste in the early stages of building design. The use of Building Information Modeling (BIM) to solve problems of systematizing information about the possibility of reusing and recycling construction waste allows us to solve ecological problems of a construction project, including the issues of choosing ecological friendly and sustainable materials for the implementation of design solutions, as well as increasing the efficiency of construction waste management.

Environmental feasibility and implications in using recycled construction and demolition waste aggregates in road construction based on leaching and life cycle assessment – A state-of-the-art review

Due to rapid population growth and urbanization, construction activities have increased worldwide resulting in generation of enormous volume of construction and demolition (C&D) waste. On one hand, C&D waste is generated during the construction, destruction, and rehabilitation of existing structures. While on the other, the transportation sector consumes large volumes of aggregates for pavement construction and maintenance. The extraction of finite natural aggregates causes potential damage to the environment. Recycled C&D waste, once converted into recycled aggregates, has the potential to be utilized in pavement layers due to its sound quality and composition; also resulting in lowering the landfill loads. This review article critically summarizes the environmental risks regarding chemical composition and leaching behavior of C&D wastes in pavements. Additionally, this review evaluates the environmental impacts of C&D waste aggregate production and application in pavements using life cycle assessment (LCA). Overall, the aim of this study is to investigate the environmental impacts and benefits of C&D waste to enable highway administrations to adopt and promote the use of C&D waste in development of sustainable road infrastructure. In this way, the review articleattemptsto promotea new era of sustainable road construction and achieve net zero waste goal.

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.

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.

Characterization and Environmental Evaluation of Recycled Aggregates from Construction and Demolition Waste in Belgrade City Area (Serbia).

Sustainable consumption of construction materials is an important segment of sustainable development goals towards reducing climate change. Since the consumption of natural aggregates raises environmental concerns, there is an increasing demand for use of recycled aggregates (RAs), as it enhances social and environmental benefits and creates a market opportunity. This paper presents the practice of using recycled construction and demolition waste (CDW) in the Belgrade city area (Serbia) as a resource. Two groups of CDW from Vinča landfill site near Belgrade are analyzed: raw material before, and RAs after, construction of a recycling facility on site. Comprehensive characterization is performed (including particle size distribution, density, water and organic pollutants content, various mechanical resistances, flakiness index, etc.) and compilation of samples analyzed and compared to show a holistic overview. The test outputs in both groups show acceptable values and meet required standards, indicating that recycled CDW generated in the Belgrade area can be used as a substitute to natural aggregates. In addition to that, the environmental and economic benefits from this use as a substitute are analyzed and discussed, proving the substantial income from sold Ras and the landscaping benefits, as well as ecological and economic benefits from energy savings.

Exploring the contributions of circular business models towards the transition of green economy in the Ghanaian construction industry

PurposeIn recent times, both academics and industrialists have undertaken research into various areas of circular business models (CBM) in a bid to promote a green economy. Yet despite numerous studies conducted, the ensuing discourse contains scant information regarding the contributions of CBM towards the transition of green economy in the construction industry. This present study therefore aims to explore the contributions of CBM in the transition towards a green economy in the Ghanaian construction industry.Design/methodology/approachA comprehensive literature review was first conducted to identify the contributions of CBM towards the transition towards a green economy. A quantitative research strategy was then adopted to collect primary questionnaire data from professionals with knowledge of CBM and the green economy from 104 participants for the study. The data gathered was analyzed using descriptive statistics and exploratory factor analysis viz. Principal component analysis.FindingsThe contributions of CBM towards the transition towards a green economy were found to be: value contributions (i.e. lower carbon footprint, lower emission of waste by the industry, value creation for clients, innovation in construction materials and methods, reduced maintenance cost, creation of energy efficient infrastructures, improved value proposition for firms, improved sustainability of the industry and reduced pressure on finite resource.); green contributions (i.e. recycling and reuse of construction waste, promotion of green building technology, increased potential for economic growth, increased resource efficiency and creation of green building market) and longevity contribution (i.e. increased life span of buildings). It was evident that CBM make significant contributions in the transition towards green economy and as such, policymakers and other stakeholders within the construction industry must adopt these models to maximize their green credentials and accrue inherent benefits associated with transitioning towards a green economy.Originality/valueThis paper presents a novel and comprehensive study that explores the contributions of CBM towards engendering a green economy. The study’s results provide construction industry stakeholders and policymakers with clear insight into the contributions of CBM towards the transition into a green economy. In practice, this study provides much needed guidance to support construction practitioners to transition towards a green economy in alignment with the United Nations' Sustainable Development Goals (SDGs).

Evaluation of Chloride Ion Attack in Self-Compacting Concrete Using Recycled Construction and Demolition Waste Aggregates

Construction and demolition waste (CDW) destined for recycling companies has great potential for use in civil construction, since it gives rise to recycled aggregates of different particle sizes that can be used in concrete. However, there is a lack of studies on the durability of concrete produced with recycled aggregates from CDW. This study analyzed the influence of incorporating recycled aggregates from CDW, sand, and gravel on the durability parameters of SCC mixtures, with and without the addition of metakaolin (MK), when subjected to two exposure conditions: outdoors and in cycles of attack by chloride ions. Five mixtures were produced: reference SCC, with natural sand and gravel; SCC with recycled sand and gravel; SCC with recycled sand and gravel and the addition of 10% MK; SAC with recycled sand, natural gravel, and the addition of 10% MK; and SCC with natural sand, recycled gravel and the addition of 10% MK. The water/binder ratio was kept constant for all mixtures and the additive dosage was adjusted according to the variation in the use of aggregates. The mechanical and durability properties were assessed using axial compressive strength, ultrasonic pulse velocity, chloride penetration, chloride ion diffusion, and electrical resistivity tests. The results showed the feasibility of using recycled aggregates from CDW in SCC. The addition of MK significantly improved the performance of SCC using these aggregates. The mixtures with added MK showed a low risk of corrosion and high resistance to chloride ion penetration, and, under highly aggressive attack conditions, it was observed that the chloride ions did not exceed the minimum cover thickness recommended for reinforced concrete structures. The addition of MK to the mix with recycled aggregates caused an 84.6% reduction in the Cl− diffusion coefficient, there was also a 40.3% reduction in Cl− penetration and an increase of up to 156.14% in electrical resistivity compared to the mix with recycled aggregates without the addition of MK. The SCC mix with recycled sand and metakaolin stood out positively compared to the others, achieving an axial compressive strength similar to the reference mix (55.10 MPa). We, therefore, conclude that it is possible to produce such a mix with acceptable performance and ensure good behavior under aggressive environmental conditions.

Study on the mechanical properties and deterioration mechanism of recycled aggregate concrete for low-grade highway pavements

This study is motivated by the imperative for sustainable construction practices, specifically focusing on recycling construction waste into low-grade highway pavements to enhance environmental sustainability and resource efficiency. The investigation explores the workability, mechanical properties, and interfacial transition zones (ITZs) of recycled aggregate concrete (RAC), emphasizing the incorporation of recycled coarse aggregate (RCA) from construction waste. The primary objective is to delineate the optimal mixture proportions of RAC that effectively balance resource utilization with the technical requisites for low-grade highway pavements. Through rigorous orthogonal testing and analysis, a mixture was identified that achieves a high RCA replacement rate while preserving workability and mechanical properties. Additionally, nanoindentation tests were employed to probe the nanomechanical properties of the ITZs in RAC, aiming to elucidate the underlying degradation mechanisms. Results reveal that the porous and rough surface of RCA significantly impacts the properties of RAC, with a marked decrease in elastic modulus and an increase in ITZ width identified as primary contributors to mechanical deterioration. Consequently, this study not only provides crucial insights for the application of RAC in low-grade highway pavements but also sets the stage for future research aimed at enhancing the sustainability and performance of recycled 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.

Assessment of the split tensile strength of fiber reinforced recycled aggregate concrete using interpretable approaches with graphical user interface

Incorporating recycled concrete aggregates into concrete represents a sustainable approach to mitigate the extraction of natural mineral resources and alleviate the adverse environmental effects associated with the concrete industry. Nevertheless, it encounters challenges due to the vulnerability of the hardened mortar adhering to natural aggregates. Thus, leading to an increased susceptibility to cracking and reduced strength. Therefore, this study utilized machine learning (ML) methods such as gene expression programming (GEP), random forest regression (RFR), artificial neural networks (ANN), ANN-Bagging, and ANN-Boosting models to forecast the split tensile strength (STS) of fiber-reinforced recycled aggregate concrete (FRRAC). To develop the models, 257 data points were gathered from experimental studies, encompassing ten influential input variables and considering the STS as the output variable. The accuracy of the models was assessed using statistical metrics. The five developed prediction models showcased excellent and reliable performance, with an impressive correlation coefficient (R) exceeding 0.80 during training and reaching 0.92 in testing. However, the GEP model outperformed the remaining four models, with an excellent R-value of 0.980 in training and 0.983 in testing. In addition, the standalone ANN model demonstrated performance on par with the ensemble ANN-Boosting model. In contrast, the ANN-Bagging ensemble model outperformed the individual ANN model, showcasing superior prediction accuracy with impressive R-values of 0.952 and 0.975 for training and testing, respectively. Moreover, the feature analysis based on SHapley Additive exPlanations (SHAP) revealed that fiber content, recycled aggregate density, cement, and water have the highest contribution in estimating the STS of FRRAC. Furthermore, a user-friendly graphical interface (GUI) has been developed to simplify the application of machine learning models in predicting the strength properties of concrete. In conclusion, the findings can encourage the utilization of FRRAC in both structural and non-structural reinforced concrete elements. Therefore, promoting the recycling and reuse of construction waste into building materials and thereby reducing environmental impact. Furthermore, incorporating recycled concrete aggregate in construction projects has the potential to decrease construction material costs, as it reduces reliance on natural resources such as natural coarse aggregate.