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China is experiencing a period of rapid urbanization and fervent construction activities, which are responsible for the accumulation of large amount of material stocks (MS). Fundamental in every society, buildings not only shape material flows before and during construction, but also during maintenance and demolition, inducing the extraction of resources and the production of construction waste. It is thus imperative to understand the amount, composition, and location of current building MS as a first step to design appropriate management strategies for an environmentally sustainable society. This research uses the latest GIS dataset of buildings in 14 representative Eastern China metropoles to quantify the current status of building MS by employing a bottom-up method. The selection of the study areas relies on the law of the primate city, which permits to quickly target the most important urban areas of a region. We review and discuss existing material intensity (MI) coefficients for Chinese buildings, and produce a new set of MIs manipulating those available in the literature. We then calculate the total MS, MS density, and per capita MS for each city. Results find that in 14 cities 7.9 Gt of building materials are currently stored in a total area of 3790 km2, resulting on an average density of 2.1 Mt/km2. The per capita building MS results being 283 t/cap, and this value correlates with a growth of the per capita GDP. We conclude the research with a hotspot analysis of the spatial distribution of the MS, identifying the MS clusters.

The large proportions of waste generated from the construction industry have led to adverse environmental and economic impacts. Consequentially, there is a need for effective construction waste management (CWM) at construction sites. This study seeks to define Building Information Modeling (BIM) dimensions and respective conceptual interactions that shape the integration of CWM with construction management. A multi-dimensional framework is proposed that leverages BIM-based automated construction waste (CW) estimation capabilities to provide guidance on CWM applications, specifically, CW disposal scheduling, disposal cost estimation, onsite reuse, and allocation of waste bins. The framework presents interactions between these CWM applications and construction management fields—scheduling, estimation, sustainability, and site planning—to enable a strategic alignment between conventional project objectives and CWM. To demonstrate the framework, a real-world pilot project is employed for the case of concrete waste. Data used are documented and tracked from the project and interviews. The results reveal a 5.3% difference between estimated and actual concrete waste quantities. Accordingly, the expected dates for scheduling concrete waste pick-up are estimated for proposed integration into the project schedule. The study estimates savings of over $35,000 from reuse and recycling. Construction activities related to a retaining wall—requiring backfill—are identified from the project schedule as opportunities for reuse. Findings reveal that waste bins could be dedicated to waste streams with high generation rates at each construction stage. Findings from this study would serve as a guide for construction practitioners in assessing key benefits of CWM in improving the scheduling, cost, and sustainability performance of construction projects.

Illegal dumping, referring to the intentional and criminal abandonment of waste in unauthorized areas, has long plagued governments and environmental agencies worldwide. Despite the tremendous resources spent to combat it, the surreptitious nature of illegal dumping indicates the extreme difficulty in its identification. In 2006, the Construction Waste Disposal Charging Scheme (CWDCS) was implemented, regulating that all construction waste must be disposed of at government waste facilities if not otherwise properly reused or recycled. While the CWDCS has significantly improved construction waste management in Hong Kong, it has also triggered illegal dumping problems. Inspired by the success of big data in combating urban crime, this paper aims to identify illegal dumping cases by mining a publicly available data set containing more than 9 million waste disposal records from 2011 to 2017. Using behavioral indicators and up-to-date big data analytics, possible drivers for illegal dumping (e.g., long queuing times) were identified. The analytical results also produced a list of 546 waste hauling trucks suspected of involvement in illegal dumping. This paper contributes to the understanding of illegal dumping behavior and joins the global research community in exploring the value of big data, particularly for combating urban crime. It also presents a three-step big data-enabled urban crime identification methodology comprising ‘Behavior characterization’, ‘Big data analytical model development’, and ‘Model training, calibration, and evaluation’.

Although construction waste consistently contributes the highest proportion of all solid waste landfilled, its collection and transportation has received little attention. This research conducts a case study of Hong Kong with the aim of unraveling the causes of ineffective construction waste management from a logistics perspective and developing strategies to improve efficiency of waste collection and transportation. We analyze 112,892 individual trips undertaken by 2,563 construction waste hauling trucks and find three critical issues, namely irrational facility choice, disorganized trip chains, and serious underloading. We design an order-to-order distance matrix, based on which we develop a combinatorial approach to optimizing construction waste collection and transportation through (1) optimal facility choice, (2) proper order sequencing, and (3) increased loading ratio. Simulation results indicate that optimal facility choice is most effective of the three strategies, reducing travel distance by 15.2% (15,256 km) and saving 15.3% (21,467 kg) in CO2-eq emissions. Combining the three strategies creates the best optimization effects, saving 20.3% of travel distance (20,346 km) and 18.2% of CO2-eq emissions (25,544 kg). Our findings provide valuable insights for construction waste management and suggest strategies (e.g., developing a work dispatch system like Uber or proper vehicle routing algorithms) for improving waste collection efficiency and reducing carbon emissions.

The construction industry plays an essential role in a country's economic growth. The industry has been criticised for activities and processes that generate high volumes of waste, whilst obstructing sustainable development goal (SDGs) targets. The circular economy (CE) increases waste minimisation by keeping materials and resources in a closed loop. This concept has continued to gain positive traction as a potential solution to achieve sustainable development. The authors argue that contextualising the circular economy (CE) as part of the discourse towards implementing the United Nations (UN) SDGs Agenda 2030 is crucial for managing the increasing amounts of waste generated by the construction industry. This paper provides a framework that establishes a detailed relationship between the SDGs, construction waste management and the CE to direct future sustainable development research, policies, and innovations. The study adopted a narrative literature review methodology. Scopus and Web of Science were scoured for relevant literature published between 2015 and 2021. Initially 65 articles were identified with this number being reduced to 24 following a detailed inspection of their applicability to the study. The findings from the articles were summarized, synthesized, and incorporated into the study. A key theme that emerged was that an understanding of the SDGs-circular economy linkages in construction waste management is integral to establishing long-term innovative solutions for developing multi-sectorial measures for waste prevention, eco-design, and re-use of materials. These linkages increase competitiveness, stimulate innovation, and boost economic growth. This study proposes that all stakeholders who generate waste should apply new innovative technologies, methods and strategies leading to transdisciplinary and transformative change.

Quantifying truck-loaded materials is a problem in many industrial operations. In construction and demolition waste (CDW) management, inspectors at disposal facilities are often required to measure the amount of different waste components loaded by incoming trucks to determine admissibility. Due to the bulky and mixed nature of construction materials, accurate quantification of specific waste categories without sacrificing operability in the field is a challenge. This study proposes a CDW volume estimation algorithm based on monocular vision which can automatically quantify from a single image the amount of specific material components, e.g., rock, gravel, and wood, in waste mixtures. The algorithm achieves a relative error of 0.065 in calculating truck bucket dimensions, and a relative error of 0.169 in estimating material-level construction waste volume. It takes 3.3 s in average to process one image. In applying the algorithm to analyze 2,914 waste truckloads received by an off-site sorting facility in Hong Kong, we observe that the facility entrance received around 800.0 m3 CDW per day of which about 10.8 m3 were rejected. Since non-inert wood/cardboard accounts for the highest proportion among all material types, this may imply that many waste dumps accepted by the facility may have been in violation of the admissibility criteria. The study contributes to the knowledge body by providing a novel, non-destructive approach to quantifying CDW via monocular vision. It can be extended to address the general problem of truck payload quantification in scenarios such as road construction, warehouse inventory management, and logistics and supply chain management.

This manuscript presents a review of the potential and challenge of using recycled concrete aggregate (RCA) as the substitute for natural aggregate (NA) in concrete mixtures. Using RCA in concrete preserves the environment by reducing the need for opening new aggregate quarries and decreases the amount of construction waste that goes into landfill. The properties of RCA such as specific gravity, absorption, and the amount of contaminant present in it contribute to the strength and durability of concrete. The quality of RCA depends on the features of the original aggregate and the condition of the demolished concrete. Some researchers have reported that the use of RCA degrades concrete properties while others have successfully produced RCA concrete with a performance that matched normal concrete (NC). In addition to the influence of RCA to concrete properties, this paper also evaluates multiple techniques to improve the performance of RCA concrete, reported cost savings in concrete production and recommendations regarding the application of RCA in concrete.

In the era of big data, data is increasingly driving the construction waste management (CWM) for minimizing the impacts on the environment and recycling construction materials. However, missing data, led by various information barriers, often undermines the decision-making and hinders effective CWM. This paper applies aggregated behavior-based Machine Learning (ML) methods to handling the project-level ‘Missing Not At Random’ (MNAR) data by using aggregated waste generation behaviors as a case study. First, we define a set of 821 waste generation behavioral features based on waste big data, then screen the indicative and decisive behaviors using automatic feature selection. Then, the most predictive ML method, trained via data of 2,451 construction projects in 2011–2016 in Hong Kong, is selected for handling the MNAR data. The experiments showed that the prediction of project missing data was satisfactory (validation F1 = 0.87, test F1 = 0.80). The contribution of this paper is to pinpoint the potential of waste big data in portraying project behaviors for more value-added applications, at the same time, to present a handling method for MNAR data that is automatic, fast, and low-cost from the CWM practitioner's perspective.

This study was designed to investigate the recent movement and current stage of China’s construction and demolition (C&D) waste recycling and reuse. Specifically, the research aimed to provide the big picture of recent C&D waste diversion practice in China, as well as to offer insights from Chinese field practitioners’ perceptions towards benefits, challenges, and recommendations of C&D recycling and reuse. This research was conducted based on a review of existing practice and a holistic approach by collecting feedback of professionals from multiple disciplines through a questionnaire-based survey. Totally 77 valid responses were received from 592 questionnaires sent. Both quantitative data and qualitative information implied that China was still at the early stage of recycling C&D wastes. Lack of client demands was identified as one of the main difficulties in C&D waste diversion. The study revealed that engineers and consultants had a more positive perception on promoting industrial training in C&D waste recycling, while construction management professionals held more conservative opinion on it. It was also found that gaining experience in C&D waste recycling and reuse would offer professionals more positive perception on the quality of products containing recycled contents. It was further implied that although governmental supervision had a high impact on China’s current C&D waste management practice, the economic viability should eventually dominate the C&D waste diversion.

Prefabrication has long been recognized as a green production technology to minimize construction's adverse environmental impacts such as waste, noise, dust, and air pollution. Previous studies reported the effects of prefabrication on construction waste minimization. However, these studies relied primarily on small data obtained by ethnographic methods such as interviews and questionnaire surveys. Research to evaluate the effects using bigger, more objective quantitative data is highly desired. This research aims to re-evaluate the effects of prefabrication on construction waste minimization by exploiting a quantitative dataset stemmed from 114 sizable high-rise building projects in Hong Kong. It was discovered that the average waste generation rates of conventional and prefabrication building projects were 0.91 and 0.77 ton/m² respectively. Compared with conventional construction, prefabrication logged a 15.38% waste reduction. Further probing into specific prefabricated components adopted in the samples, it is discovered that precast windows and walls are more conducive to waste minimization. This is coincident with the fact that these components are also widely adopted in the sample buildings. This study reconfirms the positive effects of prefabrication on waste minimization and articulates that two types of prefabricated components play relatively bigger role in minimizing construction waste. The strengths of this study lie in its statistical analyses of a valuable and objective quantitative dataset measuring prefabrication and waste generation rates. Future studies are recommended to prove the corollary - it is not what category of prefabricated component, but the actual proportion of prefabrication in the total construction volume that matters to waste minimization.

Reverse logistics (RL) concepts have brought sustainable solutions to the problems pertinent to inert construction waste (ICW) management. However, the involvement of different processes and facilities across the RL value chain makes it difficult to visualize and manage the whole process conveniently. Consequently, issues such as inadequate assessment of environmental hazards, unclear cost accrual patterns, misleading information to stakeholders, and other process-related deficiencies arise, thereby questioning the overall sustainability and alike circularity concepts. Despite the prominent role of lean management (LM) concepts in process improvements across various product-oriented sectors, its integration within RL management to solve ICW problems is almost non-existent. This paper presents a unique lean thinking-based multi-layer value stream assessment (MVSA) approach deriving from a conventional value stream mapping (VSM) technique to assess the overall RL network of ICW management. RL network design entails both facility-based and non-facility-based processes, with four different value streams, i.e., time, cost, environmental quality, and process efficiency aspects. A case study of Hong Kong demonstrates the developed MVSA approach. The case study features an assessment of the RL network's current and future states, considering multiple scenarios. Furthermore, a detailed sensitivity analysis is conducted to provide valuable insights and discussions. In the end, an agenda for continuous improvement related to the proposed MVSA approach is expounded. The research findings verify that the proposed MVSA approach can significantly contribute to the overall process improvement, better visualization, and RL network assessment, leading to effective waste management systems.

Construction waste management involves multiple participants and processes. Although existing research has developed a building information model (BIM) based estimation system, the challenge of selecting a transportation and demolition plan that provides overall construction waste management from the perspective of multiple participants remains, and how multiple participants can coordinate the overall process is still unclear. This paper develops a BIM and cost-optimisation-based decision-making system for construction and demolition waste (C&DW) transportation and demolition that is capable of coordinating involved C&DW participants and suggesting a cost-effective transportation and demolition plan. Firstly, we developed a transportation plan decision model based on the optimal cost principle. The model is capable of determining the optimal demolition company, transport company and disposal company through cost analysis, and a demolition plan decision model was developed based on the work efficiency analysis of the selected participants. Secondly, we developed a decision-making system that extracts material type and volume information about C&DW emissions and emission types from BIM models. Then the system provides a cost-effective transportation plan and formulates a demolition plan that can avoid the accumulation of C&DW on site based on the decision models. A case study of the system is presented, and the results show that the system can realise the information flow of all links in the construction waste management and improve the efficiency of decision-making concerning construction waste.

Construction waste contains inert (e.g., construction debris, rubble, earth, bitumen, and concrete) and non-inert materials (e.g., bamboo, plastics, wood, paper, and vegetation), while it is often a combination of the two when it is generated at source. The bulk density of construction waste is the yardstick information for many subsequent waste management efforts. One feasible way to derive the bulk density information is to segregate the mixture of inert and non-inert substances and examine their compositions, but clearly, this is an onerous task. This paper reports a data-driven approach to obtain the bulk densities of inert and non-inert construction waste by analyzing a big dataset of 4.9 million loads of construction waste in Hong Kong in the years 2017 to 2019. It is discovered that the means of bulk density are 336 kg/m3 for non-inert waste, 528 kg/m3 for mixed waste, and 991 kg/m3 for inert waste, and their coefficients of variation are 69%, 43%, and 29%, respectively. The research not only proved our heuristic rules concerning the bulk densities of the three generic types of construction waste, but also articulated, for the first time, their converged means and ranges. The findings can be used in adjusting the admission criteria as adopted in the governmental waste management facilities. Future research is recommended to further narrow down the bulk density ranges to provide more accurate references for construction waste management.

In this study, a Bayesian Network analysis is used to define causal behavioral determinants towards improving practices in construction waste management (CWM). For this purpose, a structured survey questionnaire was developed and administered to field workers at construction projects. The collected data was used to develop a probabilistic relational model with single- and multi-factor analysis to assess conditional probabilities underlying various determinants. The results indicate that behavior is highly influenced by attitude, past experience, and social pressure with 21, 20, and 10% higher chance of improvement by these factors, respectively. Behavior in CWM appears to be more sensitive to changes in personal factors such as attitude than corporate factors such as training. When simultaneously controlling all factors, the behavior is improved with personal factors by 9% more than with corporate factors. Additionally, it was found that the probability of having effective CWM practices on-site reaches 83% when workers have a positive attitude towards waste management, are well experienced in CWM practices, and are influenced by social pressure. Achieving this result also requires independency at work and availability of training sessions. The model raises the awareness of construction stakeholders about factors influencing workers’ behavior towards CWM and presents quantified strategies that increase the chances of minimizing the generation of construction waste. It can serve as a motivation and a decision support tool for adopting and implementing sustainable CWM practices.

This paper aims to evaluate land consumption caused by materials flow in building life cycle for feasible land conservation measures in China. As distinct from the land occupied by buildings, extended land consumption was defined as lands consumed during raw material extraction and construction waste disposal. And corresponding statistical model, including two computing formulas for single building and a statistical method for regional buildings was designed. Using the proportions of weights from raw materials to building materials and the ratios between raw material weights and destroyed land areas, extended land consumptions at construction stage and demolition stage by per square meter of floor area were calculated as target parameters respectively for three common building structures: brick-concrete, frame and steel structure. Based on building structures, predicted time of demolition and reconstruction, and the target parameters, extended land consumption from all buildings of Shenyang City from 2014 to 2064 in four situations were calculated and compared. The results illustrate that extended land consumption accounts for 1.78% of the whole city area and 29.18% of occupied land, and could be reduced by 80% by improving construction quality for longer serviceable building life and adopting prefabricated construction for greater recycling ratios of scrap building materials. Material flow caused land consumption provides an extended dimension to the concepts on land consumption; the statistical model provides a framework to quantify the relationships between building patterns and land consumption. Our approach permits more accurate land consumption prediction for decision-making in sustainable land utilization.

The waste generation rate (WGR) is usually used as a key performance indicator (KPI) to benchmark construction waste management (CWM) performance, with a view to improving the performance continuously. However, existing researches, for different reasons, only investigated a relatively small amount of construction projects, whose WGRs cannot be confidently accepted as KPIs. This study develops a set of more reliable KPIs/WGRs using an available big dataset on CWM in Hong Kong. By mining the 2,212,026 waste disposal records generated from 5764 projects in two consecutive years of 2011 and 2012, the WGRs/KPIs are revisited and refined. Demolition is found the most wasteful works. New building, and maintenance and renovation (M&R) works individually produce the least waste amount but by accumulating all M&R works, their contribution to the total amount of construction waste could be phenomenal. Based on the more reliable WGRs from the big data, CWM performance benchmarks for different categories of projects are set up. A contractor can benchmark its CWM performance against its counterparts or its past performance as ‘Good’, ‘Average’, and ‘Not-so-good’, and thus identify better CWM practices that induce superior performance. Based on the benchmarks, the government may consider setting up a WGR-step toll system to encourage those ‘Not-so-good’ contractors to perform well in the future, and initiate incentives to the companies conducting ‘Good’ projects to spur better CWM performance. Overall, the WGRs derived from the big data and more robust analyses provide a very powerful and handy tool for CWM.

Construction waste presents a significant challenge to the sustainable development in the context of rapid urbanization. Although construction waste management has been implemented at different levels, there are limited studies on the role of design professionals particularly the implementation of waste minimization by design. This paper aims to examine the influence of designers’ attitude on their waste minimization behaviour and explores the predictors of designers’ implementing waste minimization by design. Based on Ajzen's theory of planned behaviour (TPB), a hypothetic model was developed, which was consequently tested via the structural equation modelling (SEM). A questionnaire survey was conducted to collect data in Shenzhen, Mainland China. Results showed that the designers’ attitude and perceived behavioural control have positive and significant effects on their behaviour on waste minimization. However, subjective norm plays a limited role. Moreover, the total effect of perceived behavioural control is notably greater than that of attitude on designers’ behaviour. Corresponding policies are proposed to facilitate waste minimization during the design process.

With China's rapid industrialization and urbanization, building industry generates a large amount of construction waste, which is becoming a burgeoning problem for the local governments to ensure a sustainable and effective management of construction waste. There is a general agreement among researchers that construction waste recycling is an important means for curbing the deterioration of the environment in China. Previous studies have focused on the methods of waste treatment and the recycling behaviour of a single stakeholder, as well as lack of consideration of cooperation among different stakeholders. This study develops a dynamic evolutionary game model on construction waste recycling to analyse the symbiotic evolution between the behaviour of construction enterprises and recycling enterprises, in situations with or without government incentives. This research also investigates how government incentive policy affects the dynamic evolution process of the construction waste recycling. The results from this study show that subsidy to construction enterprises is essential to promote the construction waste recycling in China, but compensating recycling enterprises is not always necessary, because in certain cases as long as the construction enterprises recycle the waste, the recycling enterprises will participate in recycling spontaneously without subsidy. Finally, some suggestions and countermeasures are proposed to help achieving an efficient waste recycling management in China.

Efficiency disparity between the public and private sectors is a non-trivial issue that concerns fundamental choices of socio-political-economic systems. Waste management academia and industry also wrestle with issues relating to the choice between public and private sectors. To examine the disparity exclusively caused by “sector”, in statistics language, one needs data that is sufficiently big to control many other confounders, e.g., sites, project types, and construction technologies. This paper attempts to ascertain the construction waste management (CWM) efficiency disparity between the public and private sectors by using big data in Hong Kong. The waste disposal records of 132 projects, including 70 public and 62 private projects, were extracted and analysed. By comparing the waste generation flows (WGFs) and accumulative WGFs, it is found that, by and large, there is no significant efficiency disparity in CWM between the two sectors. However, a closer investigation discovered that the private sector outperforms their public counterpart in demolition projects, while the latter performs better in foundation and new building projects. Although there are private projects with higher CWM performance, their divergence between the best and average projects are larger than public ones. Such findings thus reject casual remarks that the private sector is more efficient in CWM. The underlying reasons maybe the waste management index practice promoted in public projects while the private sector is often incentivized to perform better CWM to save waste disposal levies. Future research is recommended to delve into the causes of the efficiency disparity and introduce CWM interventions accordingly.

The costs of construction waste handling, a scarcity of landfill sites, and requirements for sustainable construction have placed recycling of concrete—the most abundant construction material in the world—under scrutiny. Unlike recycling of aggregates, utilization of sub-sieve fractions from recycled concrete has not yet been adopted in the construction industry. In this study, we investigate the possibility of recovering residual anhydrous clinker embedded in grains of stripped mortar within these fines. Different samples of waste concrete were finely ground and studied using microscopy and chemical analyses to assess the amount of residual clinker. Its contribution to hydration processes was measured by calorimetry, and the impact of recycled concrete fines on mechanical properties of cement pastes was tested. The results indicate that residual anhydrous clinker is present in waste concrete and can be recovered by grinding. Replacing Portland cement with the recycled material in pastes led to a significant increase of tensile strength, while deterioration of compressive strength was negligible when the concrete fines contained higher amounts of residual clinker and when the amount of fines did not exceed 30% of Portland cement weight.

© 2015 Elsevier B.V. All rights reserved.Construction industry contributes a large portion of waste to landfill, which in turns results in environmental pollution and CO2 emission. Despite the adoption of several waste management strategies, waste reduction to landfill continues seeming an insurmountable challenge. This paper explores factors impeding the effectiveness of existing waste management strategies, as well as strategies for reducing waste intensiveness of the construction industry. Drawing on series of semi structured focus group discussions with experts from the UK leading construction companies, this paper combines phenomenological approach with a critical review and analysis of extant literatures. Five broad categories of factors and practices are responsible for ineffectiveness of construction and demolition waste management strategies, which subsequently results in waste intensiveness of the industry. These include end of pipe treatment of waste, externality and incompatibility of waste management tools with design tools, atomism of waste management strategies, perceived or unexpected high cost of waste management, and culture of waste behaviour within the industry. To reduce waste intensiveness of the construction industry, the study suggests that six factors are requisites. These are tackling of waste at design stage, whole life waste consideration, compliance of waste management solutions with BIM, cheaper cost of waste management practice, increased stringency of waste management legislation and fiscal policies, and research and enlightenment. The proposed strategies are not only important for achieving low waste construction projects, they are important for reducing waste intensiveness of the construction. Implementation of the suggested measures would drive waste management practices within the construction industry.

The growth in construction activities over the past two decades has resulted in a parallel increase in the amount of generated construction waste. This growth, coupled with shortages in landfill space particularly in urban areas, has proven to be a challenging stressor to the environment. Management of construction waste has thus become a problem attracting increasing attention worldwide. In this context, the quantification of waste streams generated from various construction stages is the first step for managing construction waste. In this study, a methodology for quantifying waste streams arising at various construction stages is proposed. The methodology is then tested at a field scale to estimate generation rates for major waste streams and the total construction waste generation rate for the purpose of developing a generalized construction waste management plan that can be applied at a city/regional/country level. The results of the study reveal that the total construction waste generation rate falls within the range of 38–43 kg/m2, with masonry and concrete constituting more than 60% of the total waste. The study concludes with a set of recommendations addressing the most important issues contributing to a successful implementation of an integrated construction waste management plan.

The difficulty of dealing with construction and demolition waste (CDW) on construction sites is not new and continues to be an environmental problem. Understanding the waste generated in a construction work is essential to optimize CDW management. Therefore, any tool used for establishing an estimation of the CDW that will be generated should be considered as an alternative to achieve real solutions pursuing sustainability. This paper presents the evolution of CDW flow generation in the construction of new residential buildings, and has identified that the construction activity is increasing the waste generation. In an attempt to find some solutions and provide improved alternatives, several building sites have been analysed in order to quantify the estimation of CDW generated. Results show that when using plasterboard walls the CDW generation, per m 2 of built surface can be reduced up to 15.94% compared to the use of traditional brick partitions. In addition, a model describing the accumulation of CDW throughout the project duration is proposed. This model states that CDW mainly accumulates in the middle stages of the project. This study allows an estimation of the amount of CDW to be generated in a building construction site, helping to plan the number and size of containers required at any moment of the construction process, as well as the space required for a proper CDW management.

Construction waste minimization at the design stage is a key strategy in effective waste reduction. However, it seems that few studies focus on exploratory factors that can significantly improve the design of construction waste minimization. This paper addresses this research gap by presenting a set of critical factors that inform and improve the practice of waste minimization design, particularly in the context of Shenzhen, China. Nineteen potential factors which can influence effective waste minimization are presented based on related official guidelines, reports and literature. Top institutions in Shenzhen that have received a Grade A building design certification were surveyed through a questionnaire. From this survey, six critical factors are derived: (1) large-panel metal formworks, (2) prefabricated components, (3) fewer design modifications, (4) modular design, (5) waste reduction investment and (6) economic incentive. The applicability and significance of the identified critical factors for effectively designing waste minimization are also explored. These critical factors not only provide designers and project managers with a useful set of criteria for effective design strategies to reduce construction waste, but also serve as valuable references for the government to formulate related construction waste minimization regulations.

The increasing construction and demolition (C&D) waste causes both cost inefficiency and environmental pollution. Many countries have developed regulations to minimize C&D waste. Implementation of these regulations requires an understanding of the magnitude and material composition of waste stream. Construction waste generation index is a useful tool for estimating the amount of construction waste and can be used as a benchmark to enhance the sustainable performance of construction industry. This paper presents a model for quantifying waste generation per gross floor area (WGA) based on mass balance principle for building construction in China. WGAs for major types of material are estimated using purchased amount of major materials and their material waste rate (MWR). The WGA for minor quantities of materials is estimated together as a percentage of total construction waste. The model is applied to a newly constructed residential building in Shenzhen city of South China. The WGA of this project is 40.7 kg/m 2 , and concrete waste is the largest contributor to the index. Comparisons with transportation records in site, empirical index in China and data in other economies reveal that the proposed model is valid and practical. The proposed model can be used to setup a benchmark WGA for Chinese construction industry by carrying out large-scale investigations in the future.

To tackle the large amount of solid waste generated from construction activities, Hong Kong has issued a series of construction waste management policies in the last twenty years. One of the most significant policies is the launch of an off-site construction waste sorting (CWS) program. Since its implementation in 2006, the off-site CWS program has contributed greatly to construction waste minimization by hitherto separating 5.11 million tons of construction waste in total. This paper aims at carrying out a thorough investigation into the off-site CWS program in Hong Kong. Both successful experience and existent shortcomings in relation to the CWS program are discussed in detail. Data on which the analysis and discussions are based are mainly obtained from two channels. One is from literature review and examination on government regulations and statistics, while the other is from two empirical case studies carried out at the Tuen Mun construction waste sorting facility. The findings reveal that the success of the off-site CWS program is mainly attributed to ‘sustaining policy support from the Hong Kong government’, ‘good policy execution’, ‘encouraging off-site CWS through higher disposal charges’ and ‘implementation of the trip-ticket system’. Suggestions for further enhancing the effectiveness of the off-site CWS program are also proposed. The study is not only useful for decision makers to further improve the overall effectiveness of this practice, but also provides valuable references for other countries or regions in minimizing construction waste through off-site waste sorting program.

The construction industry has always been a major generator of construction waste and is often faced with the issue of its effective management in minimising environmental pollution. This research paper focuses on the construction waste generated from the construction of high rise buildings using 3 construction methods; Conventional Construction (Category I), the Mixed System (Category II) and Industrialised Building System (IBS, Category III). The construction waste for each construction category were characterised into its mineral and non-mineral components. The construction waste usage efficiency (CWUE), waste generation, reuse and recycling rates were also calculated. The IBS (Category III) was found to be the most efficient construction method with a waste generation rate (WGR) of 0.016 tons of construction waste/m 2 floor space compared to the Mixed System (Category II) at 0.030 tons/m 2 and the Conventional Construction (Category I) at 0.048 tons/m 2 . The construction waste usage efficiency (CWUE) was the highest in Category III (IBS) at 94.1% with only 5.9% of the total construction waste in this category being disposed at landfills. The Construction Industry Development Board (CIDB) of Malaysia has recognised its benefits and has actively promoted the use of IBS in Malaysia. The waste characterisation data and its uses (reuse and recycling) obtained from this study could be used as baseline data to promote and encourage the Malaysian construction industry to adopt the use of precast technology, the Industrialised Building System (Category III) and move away from the more traditional resource hungry Conventional Construction (Category I). The inclusion of the Mixed System (Category II) in this study as an intermediate construction method was aimed at providing the link between the Conventional Construction (Category I) and the IBS (Category III). The Mixed System (Category II) incorporates both the IBS and Conventional Construction methods. The Conventional Construction (Category I) with the incorporation of new construction technologies could easily be reclassified as the Mixed System (Category II), allowing Malaysian contractors to easily adopt it. This paves the way for better understanding for the use of precast technology which eventually would result in a positive shift towards the use of the IBS (Category III) by Malaysian contractors in the future. Thus, improving the construction industry's environmental performance and commitment to sustainable development as outlined by the CIDB's Construction Industry Master Plan 2006–2015 for Malaysia.

Construction waste management (CWM) can affect society from an economic perspective, a social perspective and an environmental perspective. It is found from existing literature that scant attention has been paid to take account of the dynamics nature of the CWM system and interactions among major variables in the system when evaluating its environmental performance. Therefore, in order to fill the research gap, we develop a model for evaluating the environmental performance of CWM by using a system dynamics approach; particular focus is given to the dynamic interrelations among major variables in the CWM system and how the dynamics interactions can influence the environmental performance of CWM. The application of the proposed model is demonstrated based on a real case from the construction industry of China. The simulation results not only provide valuable information on how to improve the environmental performance of CWM in the studied project, but also help build confidence in the dynamic model in general so that it can be adopted to simulate, evaluate, and subsequently improve the environmental performance of CWM in construction projects.

Benefits of conducting on-site sorting of construction waste, typically including increasing the rates of reuse and recycling, reducing the cost for waste transportation and disposal, prolonging the lifespan of landfills designed for receiving non-inert construction waste, and lessening the pollution resulted from the huge amount of construction waste, have been extensively investigated by previous studies. However, effective implementation of construction waste sorting requires a wide range of factors involving human beings, management, technology, environment and resources. So far, we know little about how to conduct effective construction waste sorting in China. This research therefore aims to identify the critical success factors (CSFs) for on-site sorting of construction waste in China. A set of methods including CSF approach, pilot study, questionnaire survey and face-to-face interview are adopted to facilitate the identification and analysis of the CSFs. Six factors including (1) manpower, (2) market for recycled materials, (3) waste sortability, (4) better management, (5) site space, (6) equipment for sorting of construction waste, are considered the CSFs for effective on-site sorting of construction waste in Shenzhen, China. These CSFs are of great significance both to researchers and industry practitioners.

Energy and resource efficiencies are both critical to achieve building design and construction sustainability. Embodied energy is a measure of the energy required to produce, install, and maintain materials, while technical metabolism enhances building design recyclability. Nearly all types of materials can be recycled. However, the technical metabolism of the materials depends on the existence of a market for these recycled materials, the regional recycling capacities, the total energy used to recycle, and the knowledge of the workers and designers about material recycling on a construction project. Although the concepts of embodied energy and technical metabolism have been around for many years, the concepts have not been extensively applied to construction projects. This research examines the transportation energy use for recycling construction wastes and the actual rate of recycling of these projects. The study concluded that the recyclability of construction wastes and the energy required for transporting the wastes are affected by regional variables, such as the distances between project sites and recycling facilities; social variables, such as regional purchasing habits; and design variables, such as the ease of deconstruction and recycling of construction materials. These variables affect the transportation need of shipping the wastes for recycling, and the percentage of materials that can be “metabolized.” These variables have to be developed into models that would help designers produce better estimates of the embodied energy of recycling and the recyclability of construction materials.

Municipal Solid Waste (MSW) management is one of the most vital issues in the contemporary urban environments particularly in developing countries. Various aspects of MSW management in Puducherry, a small erstwhile French colony in Pondicherry Union Territory were assessed in order to improve the management practices. Its per capita generation rate and quantity in the city showed gradually increasing trend with passage of years. It was 265 tonnes/day (t/d) during 2003, which increased to 370 t/d in 2008, with a waste generation factor of 0.59 kg/capita/day. The sources of MSW classified into different categories and sub-categories showed domestic waste including kitchen waste, market waste, garden and agricultural waste, hospital waste, road and construction waste, sweeping and sanitary waste. Samples of MSW collected randomly from the main dumping yard at Karuvadikuppam in Puducherry, were categorized into biodegradable waste comprising 65% and non-biodegradable waste comprising 35%. MSW is dominated by yard waste (38.4%) followed by paper (30%) and plastics (10.4%) and the remaining 21.2% comprised of other waste. The municipalities in Puducherry adopted different methods such as door-to-door collection with segregation of garbage at source for effective MSW management. Composting of the organic waste included both aerobic composting and vermi-composting, and non-biodegradable waste was picked up and recycled for the final disposal of MSW. Awareness programs educating people regarding the problems as well as significance of MSW disposal were practiced through NGOs. However, it was found that there are some shortcomings in the existing MSW management practices, which need rectification.

The construction industry is a major waste generator and consumer of natural resources. The importance of changing traditionally adopted attitudes (such as the discard of used materials components for recycling and reuse practices) in order to create a more sustainable production model is presented in the literature. The aim of this exploratory paper is to analyze major social, economical and legal factors, which can act as barriers or opportunities in the reuse of building components. The research strategy employed is a single-embedded case study. The main unit of analysis is the reuse process, investigated by the study of the demolition sector in the city of Porto Alegre (Brazil). The process is characterized; its main phases and agents are presented and described. The supply chain management (SCM) approach is used to model the reuse process. The article summarizes major factors, which influence the reuse process, pointed in the literature and compares those with the case study findings enabling the identification of some differences. The case study findings suggest that the reuse of building components is primarily supported by economical and social aspects such as the labor cost of deconstruction and demand for reused products. Although legal mechanisms may play an important role in promoting the reuse of building components, its potential was not observed in the case study. The article also provides a critical analysis of the current state of construction waste management in Porto Alegre on issues like legislation and responsibilities, considering recent changes in national regulations. Finally, the adoption of the SCM approach has showed to be useful for the analysis of “close loop” supply chains as it enabled the identification of additional factors that can influence the reuse process.

In Malaysia, there has not yet been any widely published research that has described contractor attitudes and behaviors regarding waste management including waste reduction, reuse and recycling. Taken together, these attitudes and behaviors are crucial to understanding how construction waste management problems might be resolved. As the Malaysian construction industry is still labor-intensive, the attitudes and behaviors of individuals involved in this industry influence its growth and performance. This paper intends to provide insights on how contractor attitudes and behaviors affect waste management in the construction industry of Malaysia. A structured questionnaire survey was implemented in order to interview local contractors. This paper utilizes logistic regression analysis to assess the relationship between various factors affecting contractor attitudes and behaviors regarding waste management. The results show that contractor attitudes and behaviors regarding waste management tend to differ based on the size of the contractor, which is indicated by its group or category. Contractors that have positive attitudes toward waste management also have satisfactory behaviors, supporting Ajzen's theory of planned behavior. The important and significant factors that affect contractor attitudes toward waste management include contractor size, source reduction, reuse and recycling measures, frequency of waste collection, staff participation in training programs and waste disposal method. Factors such as construction-related education among employees, contractor experience in construction works, source-reduction measures, reuse of materials, waste disposal behaviors and attitudes toward waste management are the most significant factors affecting contractor behavior on waste management. These factors influence contractor attitudes and behaviors and are necessary to effectively improve waste management, growth and performance, as well as to reduce the environmental degradation of the construction industry.

It is well recognised that a significant amount of solid waste is produced from construction work. The increasing generation of construction waste such as used timber formwork, obsolete concrete and packaging, has caused significant pollution to the environment and risen public concern particularly in densely populated cities, such as Hong Kong. The minimization of construction waste has therefore become a pressing issue in pursuing the practice of sustainable construction. This paper shows the betterment of replacing in situ concreting with precast slabs for temporary works to improve sustainable construction performance. Construction waste from the obsolete concrete constitutes a large part of the construction solid waste in a typical building project. The reduction on the obsolescence by using precast slabs can significantly contribute to improving sustainable construction performance. This study identifies cost saving and the betterment of environmental performance by using precast concrete slabs over the in situ concreting. The data used for analysis in the paper were collected from statistics reports and a case study in Hong Kong construction practice. From the case study results, about 43.93%, 64.01% and 70.70% of the cost of using cast in situ concreting can be saved by reusing precast slabs once for temporary works, twice and three times respectively. The findings provide evidence for promoting the use of precast slabs for temporary works, and contribute to the improvement of sustainable construction performance.

Construction waste has a major impact on the environment. With the demands in implementing major infrastructure projects in Malaysia, together with many commercial building and housing development programmes, a large amount of construction waste is being produced by the construction sector. Thus, waste minimisation is an important area of concern in the implementation of the construction waste management in the construction industry of Malaysia. This study identified 12 waste minimisation factors (WMF) in implementing construction waste management in the construction industry. This study provides empirical evidence on the significant level of contribution and the level of practice among the waste minimisation factors by following the model of weighted average and minimisation and practiced index value. The results of the analysis indicate the most significant, least significant and significant factors that contribute to waste minimisation and the most practiced, least practiced and practiced waste minimisation factors in the Malaysian construction industry. The findings will assist in the formulation of appropriate policy interventions in addressing the construction waste management problem in Malaysia and indirectly improving the quality of construction in the country.

Construction waste is becoming a serious environmental problem in many large cities in the world. In Malaysia, the construction industry generates lots of construction waste which caused significant impacts on the environment and aroused growing public concern in the local community. Thus, the minimisation of construction wastes has become a pressing issue. This paper is based on a case study which involved construction waste generation and composition as well as reuse and recycling in the site. The case study also analysed the economic feasibility of waste minimisation such as reusing and recycling of construction waste materials by performing a benefit–cost analysis. This study provides an idea of the amount of waste generation, sources and compositions as well as reuse and recycling of materials on the construction sites taking into account the economic dimension. The study shows that waste minimisation is economically feasible and also plays an important role for the improvement of environmental management. In this view, economic instruments for minimising construction waste can be used to raise revenue for environmental policy, encourage prevention efforts, serve to discourage the least desirable disposal practices, as well as to avoid the negative consequences of environmental unfriendly treatment and disposal practices of construction waste materials.

Environmental problems have been considered as a serious situation in the construction. Waste management is pressing harder with the alarming signal warning the industry. Reuse, recycling and reduce the wastes consider as the only methods to recover those waste generated; however, the implementations still have much room for improvement. This paper reviews the technology on construction waste recycling and their viability. Ten material recycling practices are studied, including: (i) asphalt, (ii) brick, (iii) concrete, (iv) ferrous metal, (v) glass, (vi) masonry, (vii) non-ferrous metal, (viii) paper and cardboard, (ix) plastic and (x) timber. The viable technology of the construction material recycling should be provided an easy reference for future applications.