Recycling Of Construction Waste Research Articles

A Novel Environmentally Friendly Vegetated Three-Layer Landfill Cover System Using Construction Wastes But Without a Geomembrane

The recycling and reuse of construction waste in landfill covers help reduce environmental pollution and promote sustainability. Further enhancement of the performance of the environmentally friendly landfill covers can be made by using vegetation as it is a low-cost, ecologically pleasant solution. Most related studies of vegetation were carried out in single-layer uniform soil while plant effects on water infiltration in layered soil such as a three-layer landfill cover system remain unclear. This keynote presents an integrated research approach combining laboratory one-dimensional tests as well as a 4-year full-scale field trial located in humid climates to explore the hydrological effects of plants on the performance of a novel three-layer landfill cover system using recycled concrete but without the installation of a geomembrane. Matric suction induced by plants was preserved to a greater extent under a novel vegetated three-layer landfill cover than under a bare cover even after an extreme rainfall event with a return period of greater than 1,000 years in humid regions like Hong Kong. During the 4-year field trial, the measured maximum annual percolation was 26 mm in the three-layer bare cover system, which was less than the US EPA-recommended 30 mm. Due to the presence of grass roots, the measured amount of annual percolation in the vegetated landfill cover was further reduced by up to 22%. Both the laboratory tests and field trial demonstrated that the vegetated three-layer landfill cover system using recycled concrete even without a geomembrane can effectively reduce percolation in humid climates.

A decision-support framework for planning construction waste recycling: A case study of Shenzhen, China

Construction waste recycling is to turn construction waste materials into new resources for use. It is often considered in waste management plans, in which a central dilemma is to ponder the on-site and off-site options. Both recycling options have their respective strengths and weaknesses in dealing with internal and external factors related to site, time, cost, market, and government. However, no previous study has consciously considered the two options by putting them together with the factors in a structured model to support managers in devising their waste management plans. This study aims to develop a decision-support framework to help plan on-site and off-site construction waste recycling. It does so by adopting the qualitative research methods of case study, site visits and semi-structured interviews in Shenzhen, China. Two generic factors, namely (a) project characteristics (e.g., site constraints, time allowed, and project scale), and (b) industrial and governmental supports (e.g., transportation, recycling technology, the material market, regulations, and government subsidies), are found to determine the technical and economic viability of a particular recycling option. The two factors interact with each other and evolve over time and context to effect. This paper further articulated and organized their dynamics in a construction waste recycling decision-support framework. The research can help maximize the practicality of waste management plans. It is also of value to enhance construction waste management in the long run.

Sustainable New Product Development: a decision-making tool for the construction industry

ABSTRACT During the last decades, environmental sustainability has acquired growing importance in different productive sectors. The construction sector, aware of its environmental impacts, searches for mitigation within both processes and inputs. One of these mitigation strategies is the recycling of construction and demolition waste within the production chain. This paper deals with the proposition and application of a systematic decision-making tool in the context of the construction industry. The proposed procedure introduces a tool for Sustainable New Product Development using Quality Function Deployment to analyse the use of recycled aggregate for making concrete blocks in a multivariate context. That tool allows requirements identification and prioritisation considering the perspectives of both customers and developers, as well as standards and environmental aspects. Some results of a real case application are presented, and the benefits and potential barriers related to its adoption are discussed. These results contributed to the identification of trade-offs associated with the challenge of comparing alternative construction materials. It was also possible to identify that the use of recycled materials does not necessarily ensure that a product is more environmentally friendly than others.

Determinants Affecting Purchase Willingness of Contractors towards Construction and Demolition Waste Recycling Products: An Empirical Study in Shenzhen, China.

Waste recycling is a critical method to effectively address environmental issues raised by construction and demolition waste (C&DW). As highlighted in previous studies, the contractor is considered the primary purchaser for recycled C&DW products. However, there is a limited understanding of the factors affecting the contractor’s purchase willingness towards C&DW recycling products. This study investigated these key drivers using the Exploratory Sequential Mixed Approach. Firstly, a hypothetical model was developed based on the theory of planned behavior (TPB). Secondly, a questionnaire survey was then employed in data collection. Thirdly, structural equation modeling (SEM) was adopted for data analysis. It is revealed that multiple factors directly affect the contractor’s purchase willingness towards C&DW recycling products. These factors include government measures, the contractor’s attitude, perceived behavioral control, perceived consumer effectiveness, and subjective norms. Besides, recycling product information indirectly affects the contractor’s purchase willingness. Based on the findings, the study provides strategies for the government, contractors, recycling enterprises, and public buyers to increase C&DW recycling products’ purchase willingness. Findings derived from the empirical study can be used as a theoretical reference for government departments to develop related promotion policies. Moreover, the suggestions provided are helpful to guide recycling enterprises to promote their products.

Economic benefits of construction waste recycling enterprises under tax incentive policies.

To further explore the development of construction waste recycling enterprises and promote the recycling of construction waste resources in China, a system dynamics model of the economic benefits of construction waste recycling enterprises is established using the system dynamics method and taking the tax incentive of the Guangzhou Municipal Government as an example. The economic benefits of construction waste recycling enterprises are analyzed from the perspective of the total cost, total revenue, and total recycling amount. The results of the MATLAB simulation and numerical analysis show that (1) by simulating the effects of different taxes such as value-added tax (VAT), education surcharge, urban construction tax, and enterprise income tax on the economic benefits of construction waste recycling enterprises, it is found that when tax incentives reach 70%, the VAT favorable policies bring the highest gains, followed by enterprise income tax, whereas favorable education surcharge policies and urban construction tax have the least impact on economic benefits. (2) Taking the monetary subsidy of the Guangzhou municipal government as an example, it is estimated that the total revenue of construction waste recycling enterprises will increase by 33.56% annually in 2030. When the new production technology is adopted, the return on investment (ROI) will reach 46.8% in 2030 compared to previous technological improvements. In the simulation scenario, the ROI will be 42.2%, which has a good incentive effect on the cost control of enterprises. (3) Increasing the available power to VAT and corporate income tax can improve the profitability of construction waste recycling enterprises in China; however, tax incentive policy will no longer be the main factor affecting the benefits of enterprises when a certain time is reached. (4) It is suggested that the government improves the relevant tax laws incentive policies, increase tax incentives, and add equipment tax incentive policies, actively change the tax mode, and increase indirect tax models to improve the economic benefits of enterprises. The research results provide a decision-making reference for the government to formulate laws and policies related to the economic benefits of construction waste recycling and promote the development of the construction waste recycling industry, the development of new industries, such as waste recycling and treatment, and the formation of industrial chains, to achieve the strategic goal of sustainable development.

Dynamic game strategies for construction and demolition waste recycling with learning and reference effects

Construction and demolition waste (C&DW) recycling can effectively reduce the environmental impacts caused by the massive amounts of untreated C&DW, and can promote the sustainable development of the construction industry. This study aims to provide relevant insights for the implementation of C&DW recycling, and can be practically used to guide participants' dynamic strategies in the presence of both the reference price effect and cost learning effect. Based on game theory, a static model is developed as a benchmark, including a construction materials manufacturer and a C&DW recycler under a government subsidy. Then, a dual-period dynamic model combining the learning and reference effects is established to broaden the understanding of C&DW recycling management. On this basis, the decisions and revenues of players are compared and analysed, and managerial insights are obtained through numerical analysis. It is found that both the learning and reference effects affect the manufacturer's decisions and revenues, and that the reference effect has a much greater impact on profit than the learning effect. In addition, only the learning effect has a positive influence on the recycler's recycling efforts and profits, thereby promoting C&DW recycling and reducing environmental impacts. Moreover, government subsidies always benefit the environment and recycler, and as the learning ability becomes stronger, the subsidy becomes more efficient in reducing the environmental impacts and improving the recycler's profit. Comparatively, the impact of subsidy on the manufacturer's profits depends on the learning ability. When the learning ability is relatively high, a higher subsidy is detrimental to the manufacturer in the short term but benefits it in the long term.

Characterising the resilient behaviour of pavement subgrade with construction and demolition waste under Freeze–Thaw cycles

Recycling construction and demolition (C&D) waste as fillers in pavement subgrade is a sustainable paving technology with environmental and economic merits. The performance of pavement subgrade with C&D waste depends on its dynamic resilient modulus. Meanwhile, freeze–thaw cycles are also an important issue for engineering in seasonal frozen regions. However, research on characteristics of the dynamic resilient modulus of C&D waste, especially the properties under freeze–thaw cycles, is limited. To this end, this study aims to reveal the variation law of the dynamic resilient modulus of C&D waste under repeated freeze–thaw cycles and establish a reasonable performance prediction model. This study conducts a series of laboratory tests after various freeze–thaw cycles. Results indicate that the soil–water characteristic curves of C&D waste with different compactness and number of freeze–thaw cycles can be well described by Van Genuchten’s model. Moreover, the dynamic resilient modulus enhances with the increase of matric suction, compactness, deviator stress and minimum bulk stress and exhibits a stress-hardening characteristic. Freeze–thaw cycles attenuate the matric suction and dynamic resilient modulus of C&D waste. Besides, high moisture contents, low stress levels and more freeze–thaw cycles all aggravate the attenuation of the dynamic resilient modulus in certain extent, but the attenuation is not sensitive to the compactness. Finally, this study establishes a high-accuracy prediction model of the dynamic resilient modulus considering the effect of repeated freeze–thaw cycles. This study can supply useful information on the application of C&D waste in pavement subgrade in seasonal frozen regions.

Discussion on Key Influencing Factors of Construction and Demolition Waste Recovery and Recycling Management in China

Through the literature summary, a list of key factors affecting construction and demolition (C&D) waste recycling and resource governance was identified from three levels: government governance and support, social public participation, and related enterprise participation. By building a collaborative driving model of C&D waste recovery and recycling governance, and based on the system dynamics of C&D waste recovery and recycling governance causal loop diagram, it shows the synergy between various influencing factors of the C&D waste recovery and recycling management. Conclusion: suggestions are come up with promote the development of C&D waste recovery and recycling management by increasing policy guarantees and financial support, encouraging public participation, stimulating the participation of relevant enterprises, and improving the effects of C&D waste recovery and recycling.

Recycling of construction and demolition waste and its impact on climate change and sustainable development

The huge generated amounts of construction and demolition (CD reduce the energy consumption; offset the greenhouse emissions where about 39% is attributed to the construction industry; recover added-value materials; create jobs; and protect the earth’s natural resources. The results of analysis highlight the importance of on-site recycling and segregation at source for offsetting the greenhouse gas emissions as well as mitigating the risks of the hazardous portion. The results of this analytical review promote the importance of diverting construction and demolition waste from landfill sites to recycling and help decision makers to adopt the recycling option to achieve sustainable development.

Current Applications of Recycled Aggregates from Construction and Demolition: A Review.

A literature review comprising 163 publications published over a period of 26 years from 1992 to 2018 is presented in this paper. This review discusses the generation and recycling of construction and demolition waste (CDW) as well as its main uses as raw materials for the construction engineering sector. This review pays attention to the use of CDW aggregates for sand, pavements/roads, bricks, ceramics, cementitious materials, and concrete productions, as well its uses as eco-friendly materials for water decontamination. The physical-chemical and mechanical characteristics of recycled aggregates play an important role in their correctly chosen applications. The results found in this literature survey allow us to conclude that recycled aggregates from CDW can be successfully used to produce construction materials with quality comparable to those produced with natural aggregates. We concluded that the use of CDWs as raw materials for manufacturing new construction materials is technically feasible, economical, and constitutes an environmentally friendly approach for a future construction and demolition waste management strategy.

Usinas de reciclagem de entulho e os entraves existentes no setor da construção civil: uma pesquisa exploratória

Com o objetivo de reciclar resíduos de obras, as Usinas de Reciclagem de Entulho (URE) reduzem o impacto ambiental da indústria da construção civil. Assim, este artigo discute o papel das URE na promoção de variáveis ambientais na gestão de resíduos de construção. Para isso, utilizou-se metodologia de estudo de caso em sete URE localizadas na região de São Paulo, além de entrevistas com gestores das usinas. O presidente da Associação Brasileira de Reciclagem de Resíduos da Construção Civil e Demolição e engenheiros experientes em obras civis também foram entrevistados. Conclui-se que as URE têm potencial para promover a inserção de variáveis ambientais no setor de construção civil, porém, existem muitas barreiras. Estas incluem a falta de programas de qualidade para agregados reciclados, o uso de métodos de produção ineficientes, baixa qualificação de mão-de-obra, falta de esclarecimentos ao mercado e ausência de leis que incentivem o uso de resíduos.

Green Blocks Made of Recycled Construction Waste using Recycled Wastewater

Green Blocks Made of Recycled Construction Waste using Recycled Wastewater

Use of thermally modified waste concrete powder for removal of Pb (II) from wastewater: Effects and mechanism.

Exploring effective uses of waste concrete powder (WCP), produced from recycling of construction & demolition waste is beneficial to the environment and sustainable development. In this study, WCP was first treated thermally to enhance the ability to remove Pb (II) from aqueous solutions. The experimental results revealed that the thermal treatment could enhance adsorption capacity due to modification of calcium bonding and pore structure of WCP. Preparation parameters such as temperature, particle size, and water-cement ratio were investigated to obtain the optimal operational conditions. Batch adsorption experiments were performed to explore influence factors of pH (1.00-6.00), ionic strength (0.05-2mol/L), dosage (2-50 g/L), and temperature (25-45°C). The pseudo-second-order kinetics model could adequately describe the adsorption process, and the Langmuir model was capable to predict the isotherm data well in the low concentration region (C0<500mg/L). The maximum uptake capacity for Pb (II) calculated by Langmuir model at 25, 35 and 45°C were 46.02, 38.58 and 30.01mg/g respectively, and the removal rate of Pb (II) was 92.96% at a dosage of 50 g/L (C0=1000mg/L). Precipitation, ion exchange, and surface complexation were identified to be the main mechanisms of Pb (II) adsorption through microscopic investigation by SEM-EDX, XRD, FTIR, XPS, and BET inspections. The study confirms that the WCP after thermal modification, can be selected as a promising adsorbent for the high performance and eco-friendliness.

Evaluating the creep characteristics of recycled construction waste materials under saturated and dry condition

The creep deformation characteristics of recycled construction and demolition waste (CDW) filler are important factors affecting its road performance. In this paper, a series of laboratory tests are carried out on CDW filler, including gradation test, compaction test, California bearing ratio (CBR) test, and creep test, and the road performance of different ratios of recycled CDW filler is systematically studied. The mechanical properties of different ratios of CDW materials can meet the requirements of subgrade filler in the specification. Through the creep test, it can be seen that the elastic-plastic deformation speed of CDW material is fast and the duration is short. The creep deformation stage is opposite. Combined with the theoretical analysis, it is found that the t/e-t curve under each stress level has a good linear relationship. The relationship between strain and time is hyperbolic, and the relationship between parameters A, B, and load is a power function. The creep process belongs to attenuation creep, which conforms to the Kelvin model.

Adsorption characteristics of recycled construction waste particles for ammonia-nitrogen in rainfall runoff

In order to explore the removal method of ammonia nitrogen in water and solve the disposal problem of construction waste.After the construction waste is crushed,the particles with different sizes (recycled particles for short) are screened out for ammonia nitrogen adsorption in simulated wastewater.SEM,EDS and BET were used to characterize the recycled particles, and the effects of different external factors on adsorption efficiency and ammonia nitrogen removal rate under dynamic environment were investigated.The results show that: The surface of the recycled particles was rough and had a large number of pores.The adsorption process follows the pseudo-second kinetics and Langmuir isotherm adsorption model;the maximum adsorption capacity of the recycled particles of 0—2mm, 2—3mm, 3— 5mm and 5—10mm were 0.1169mg/g, 0.1213mg/g, 0.1200mg/g and 0.1182 mg/g, respectively;the optimal pH was 6—7; Na+ had a slight effect on ammonia nitrogen adsorption.In the static adsorption experiment,the large size recycled particles have a higher adsorption capacity,while in the dynamic adsorption experiment,the small recycled particles have a higher adsorption capacity.

Preparation and Characterization of Chabazite from Construction Waste and Application as an Adsorbent for Methylene Blue

Construction waste, produced from building projects, was utilized to prepare chabazite by alkali fusion hydrothermal synthesis method. The synthesized chabazite was used as an adsorbent for the removal of methylene blue (MB). XRD, FTIR, and N2 adsorption/desorption curves were adopted to describe the physical and chemical properties of the samples. The results show that the synthesized chabazite possesses crystalline structure, typical functional groups, and large specific surface area of 421.34 m2 g-1. Adsorption isotherms and kinetic curves show that the adsorption process follows the Langmuir model and pseudo-second-order kinetics model. The maximum adsorption capacity of MB on the synthesized chabazite reaches up to 129.18 mg g-1 at 298 K, which is about 16 times that of construction waste. The removal rate of MB reaches more than 90%, and the adsorbed amount is about 35 mg g-1 after 1 h at 298 K. Thermodynamic parameters, namely [Formula: see text], [Formula: see text], and [Formula: see text] of -12.83 kJ mol-1, -27.37 J mol-1 K-1, and -4.68 kJ mol-1 at 298 K, respectively, indicate that the adsorption of MB on the chabazite is physical, orderliness-tended, and spontaneous process. Moreover, the synthesized chabazite has a good property of regeneration and reuse. The results indicate that using construction waste to prepare chabazite in application as an adsorbent is feasible, which provides a novel and environment-friendly way for recycling construction waste.

RETRACTED: Simulation of microbial enhanced recycled aggregate preparation system based on artificial intelligence and embedded processor

Construction waste recycling is prevented by its high water absorption rate and the weak bond of the new cement paste. This problem is exacerbated by the fact that Requirements for Accreditation Scheme (RFAS) recycled porridge production. To explore the possibility of repeated use of the RFAS system, it is proposed in the integrated study of Microbial Carbonate Precipitation (MCP) derived from RFAS. Due to its rapid construction, the demand for concrete raw materials, especially coarse aggregates, increases the risk of premature erosion of natural resources. Alternative energy sources for raw materials delay the possibility of this initial exhaustion. Recycled Coarse Aggregate (RCA) played an important role as a ready-mixed concrete substitute. Natural Coarse Aggregate (NCA) changes. Previous studies have shown that RCA's special reinforcing concrete lags behind NCA. I hope that may be due to the microstructure of the calcium carbonate hailstone. Recycling aggregate has high water absorption and crushing indicators. In recent years, the integrated cycle has changed the new treatment model biopsy. Degradation-enhanced protocols have been implemented to change the nature of the motor in circulation. Famous for using the information protocol learning machine based on extracting and source information, it comes on a hardware platform provided that vendors compete between the FPGA and the GPU to run intensive computational learning algorithms quickly and efficiently. Deep learning, which is considered to be the key point by which drivers compare the most advanced machine learning applications.

ПЕРЕРАБОТАННЫЙ СТРОИТЕЛЬНЫЙ ОТХОД КАК БЕТОННЫЙ ЗАПОЛНИТЕЛЬ ДЛЯ УСТОЙЧИВЫХ СТРОИТЕЛЬНЫХ МАТЕРИАЛОВ

In this work, an experimental study is conducted to compare the properties of aggregate from concrete waste generated during demolition, concrete laboratory waste and natural aggregates – which are used as control samples. The study examines the possibility of using demolition waste to develop building materials with stable properties, in order to obtain economic benefits from the disposal of man-made waste. Initially, the production of aggregates from waste is carried out by crushing concrete scrap from demolition waste and laboratory waste, followed by the study of their physical and chemical properties to obtain aggregates and concrete mixtures, the production of samples, and the determination of compressive, flexural and tensile strength. The correlation between the results obtained from various experiments is analyzed and a linear correlation between the compressive strength and other established mechanical properties is noted. The possibility of recycling construction waste, leading to the solution of several problems, is presented: reducing the cost of industrial waste disposal and improving the physical and mechanical properties of concrete by introducing it as a filler.

STATE INNOVATION POLICY FOR GREEN TECHNOLOGIES SUPPORT IN CONSTRUCTION

The purpose of the paper is to determine the status and areas of improvement of state policy to support the development of green technologies in construction. Methodology. This review is based on the characteristics of individual areas of implementation of green technologies in construction. Possibilities of using renewable sources in the process of construction and operation of buildings are considered. It is established that different methods of energy production are used in energy efficient houses. These include photovoltaic solar panels, heat pumps, photothermal collectors, geothermal waters, mini hydroelectric power plants. It is emphasized that the energy consumption of such buildings should also be reduced; for the reason of special architectural design solutions, the energy-efficient materials with high thermal insulation properties are used. The peculiarities of the policy of stimulating the increase of energy efficiency of buildings in Ukraine are considered, the conclusion on its insufficient efficiency is given. The reason for ineffectiveness of the incentive policy is figured out. The directions for reduction of air and water pollution by filtration and use of rain and melt water for household needs are considered. It is established that the active implementation of innovation is impossible mainly due to obsolete housing and worn-out utilities. Eco-design is also used to increase energy efficiency in construction and architects must actively use passive and active methods of designing houses in different climatic conditions. Green construction also involves recycling of construction waste. Improving the environmental efficiency of buildings and structures involves the use of modern insulation materials, coatings. Currently, nanomaterials with unique properties are becoming widespread in construction. They have increased physical characteristics, in particular, accumulated thermal radiation, provided significant energy savings in winter and summer. The results of the study showed that the state regulatory policy (innovation policy, support of science and R&amp;D, technology transfer, price policy regulation, updating of technological regulations) has an extremely important role in stimulating the spread of green technologies in construction. Practical implications. The most important areas of public policy in construction are: the implementation of environmental energy and quality international standards for construction products; stimulating consumer demand for environmentally friendly innovative solutions, including through “green” public procurement, setting reasonable prices for energy resources, stimulating the implementation of a holistic concept of product life cycle; development of financial mechanisms to support the demand for cleaner technologies and innovations.

Prediction of construction waste in representative cities of North and South based on Grey Model

With the orderly promotion of construction waste treatment in China, the process of construction waste reduction is also gradually launched. At present, the production of construction waste in many cities is in the historical high decline stage. In order to better plan the capacity of urban construction waste treatment and recycling, it is necessary to forecast the output of construction waste in a period of time in the future. Based on the historical data from 2012 to 2018 in the statistical yearbook, this paper forecasts the construction waste production from 2020 to 2023 in Shenyang Dalian, the core city of Northeast China, and Guangzhou and Shenzhen, the provincial capitals of Guangdong Province. By comparing the growth trend of population with the growth trend of construction waste, it is found that the growth of construction waste is along with the increase trend of population. Meanwhile, four suggestions for urban waste disposal are provided.