Hongping Yuan

An empirical investigation of construction and demolition waste generation rates in Shenzhen city, South China.

The construction and demolition waste generation rates (C&D WGRs) is an important factor in decision-making and management of material waste in any construction site. The present study investigated WGRs by conducting on-site waste sorting and weighing in four ongoing construction projects in Shenzhen city of South China. The results revealed that WGRs ranged from 3.275 to 8.791 kg/m(2) and miscellaneous waste, timber for formwork and falsework, and concrete were the three largest components amongst the generated waste. Based on the WGRs derived from the research, the paper also discussed the main causes of waste in the construction industry and attempted to connect waste generation with specific construction practices. It was recommended that measures mainly including performing waste sorting at source, employing skilful workers, uploading and storing materials properly, promoting waste management capacity, replacing current timber formwork with metal formwork and launching an incentive reward program to encourage waste reduction could be potential solutions to reducing current WGRs in Shenzhen. Although these results were derived from a relatively small sample and so cannot justifiably be generalized, they do however add to the body of knowledge that is currently available for understanding the status of the art of C&D waste management in China.

A framework for understanding waste management studies in construction

During the past decades, construction and demolition (C&D) waste issues have received increasing attention from both practitioners and researchers around the world. A plethora of research relating to C&D waste management (WM) has been published in scholarly journals. However, a comprehensive understanding of the C&D WM research is somehow absent in spite of its proliferation. The aim of this paper is to develop a framework that helps readers understand the C&D WM research as archived in selected journals. Papers under the topic of C&D WM are retrieved based on a set of rigorous procedures. The information of these papers is then analyzed with the assistance of the Qualitative Social Research (QSR) software package NVivo. A framework for understanding C&D WM research is created based on the analytic results. By following the framework, a bibliometric analysis of research in C&D WM is presented, followed by an in-depth literature analysis. It is found that C&D generation, reduction, and recycling are the three major topics in the discipline of C&D WM. Future research is recommended to (a) investigate C&D waste issues in wider scopes including design, maintenance and demolition, (b) develop a unified measurement for waste generation so that WM performance can be compared across various economies, and (c) enhance effectiveness of WM approaches (e.g. waste charging scheme) based on new WM concepts (e.g. Extended Producer Responsibility). In addition to the above research findings, the approach for producing the research framework can be useful references for other studies which attempt to understand the research of a given discipline.

A dynamic model for assessing the effects of management strategies on the reduction of construction and demolition waste

During the past few decades, construction and demolition (C&D) waste has received increasing attention from construction practitioners and researchers worldwide. A plethora of research regarding C&D waste management has been published in various academic journals. However, it has been determined that existing studies with respect to C&D waste reduction are mainly carried out from a static perspective, without considering the dynamic and interdependent nature of the whole waste reduction system. This might lead to misunderstanding about the actual effect of implementing any waste reduction strategies. Therefore, this research proposes a model that can serve as a decision support tool for projecting C&D waste reduction in line with the waste management situation of a given construction project, and more importantly, as a platform for simulating effects of various management strategies on C&D waste reduction. The research is conducted using system dynamics methodology, which is a systematic approach that deals with the complexity - interrelationships and dynamics - of any social, economic and managerial system. The dynamic model integrates major variables that affect C&D waste reduction. In this paper, seven causal loop diagrams that can deepen understanding about the feedback relationships underlying C&D waste reduction system are firstly presented. Then a stock-flow diagram is formulated by using software for system dynamics modeling. Finally, a case study is used to illustrate the validation and application of the proposed model. Results of the case study not only built confidence in the model so that it can be used for quantitative analysis, but also assessed and compared the effect of three designed policy scenarios on C&D waste reduction. One major contribution of this study is the development of a dynamic model for evaluating C&D waste reduction strategies under various scenarios, so that best management strategies could be identified before being implemented in practice.

A model for evaluating the social performance of construction waste management

It has been determined by existing literature that a lot of research efforts have been made to the economic performance of construction waste management (CWM), but less attention is paid to investigation of the social performance of CWM. This study therefore attempts to develop a model for quantitatively evaluating the social performance of CWM by using a system dynamics (SD) approach. Firstly, major variables affecting the social performance of CWM are identified and a holistic system for assessing the social performance of CWM is formulated in line with feedback relationships underlying these variables. The developed system is then converted into a SD model through the software iThink. An empirical case study is finally conducted to demonstrate application of the model. Results of model validation indicate that the model is robust and reasonable to reflect the situation of the real system under study. Findings of the case study offer helpful insights into effectively promoting the social performance of CWM of the project investigated. Furthermore, the model exhibits great potential to function as an experimental platform for dynamically evaluating effects of management measures on improving the social performance of CWM of construction projects.

A system dynamics model for determining the waste disposal charging fee in construction

The waste disposal charging fee (WDCF) has long been adopted for stimulating major project stakeholders’ (particularly project clients and contractors) incentives to minimize solid waste and increase the recovery of wasted materials in the construction industry. However, the present WDCFs applied in many regions of China are mostly determined based on a rule of thumb. Consequently the effectiveness of implementing these WDCFs is very limited. This study aims at addressing this research gap through developing a system dynamics based model to determine an appropriate WDCF in the construction sector. The data used to test and validate the model was collected from Shenzhen of south China. By using the model established, two types of simulations were carried out. One is the base run simulation to investigate the status quo of waste generation in Shenzhen; the other is policy analysis simulation, with which an appropriate WDCF could be determined to reduce waste generation and landfilling, maximize waste recycling, and minimize the waste dumped inappropriately. The model developed can function as a tool to effectively determine an appropriate WDCF in Shenzhen. Further, it can also be used by other regions intending to stimulate construction waste minimization and recycling through implementing an optimal WDCF.

Major obstacles to improving the performance of waste management in China's construction industry

Purpose – The generation of construction and demolition waste in China is a pressing need to be minimized in order to alleviate the environmental burden. The effectiveness of implementing construction and demolition waste management in this economy, however, is very limited due to various barriers. Therefore, this paper aims to explore the major obstacles to managing construction and demolition waste in China.Design/methodology/approach – The views from Chinese practitioners were collected via a questionnaire survey. The respondents were invited to rate a total of 16 obstacles that hinder the effective implementation of construction and demolition waste management as gleaned from previous literature and six semi‐structured interviews. The results of the questionnaire were analyzed by ranking analysis and factor analysis.Findings – The findings show that “lack of a well‐developed waste recycling market”, “insufficient regulation support” and “waste reduction does not receive sufficient attention in constru...

Dynamic modeling of construction and demolition waste management processes: An empirical study in Shenzhen, China

Purpose – The aim of this paper is to develop a model based on system dynamics (SD) approach, which integrates three subsystems for simulating construction and demolition (C&D) waste management in Shenzhen, Mainland China.Design/methodology/approach – SD approach was first used to construct the model for C&D waste management in Shenzhen. The model was then converted for running on computer through the software package “iThink”, which was specifically designed for SD modeling. The data required for model simulation was derived through various ways, including literature review, examination of official reports and yearbooks, and questionnaires. After all the parameters in the model were determined, simulation was carried out.Findings – The model proposed in this research can provide an experimental simulation platform to investigate the complexity and interdependencies of factors in managing C&D waste in Shenzhen, Mainland China. The simulation results show that the pressing situation of C&D waste management...

An AHP/DEA Methodology for Assessing the Productive Efficiency in Construction Industry

A two-stage methodology integrating analytic hierarchy process (AHP) and data envelopment analysis (DEA) methods for analyzing and assessing the productive efficiency in construction industry was proposed. This paper discussed the productive efficiency of the construction industry in Shanghai using the statistic data in Shanghai from 1997 to 2007. The results indicate that the index selection process based on AHP is more objective and the integrated AHP-DEA methodology is suitable and reliable for productive efficiency assessing in construction industry. Meanwhile, the proposed assessing index will be valuable references for similar regions in Mainland China.

An Investigation of Demolition Waste Management: Case of Shenzhen in China

A huge amount of demolition waste was produced during the Chinese urban renewal process. How to promote the material recycling rate and therefore to reduce the environmental impacts has been a significant challenge. However, there is a lack of research revealing the flows and key procedures of demolition waste management. To fill the research gap, this study conducted in-depth interviews with 15 on-site managers involved in demolition projects in Shenzhen of China. As a result, the flows, key management processes and measures have been obtained. Particularly, the key procedures and waste management measures have been identified with a Process Mapping Approach (PMA). The results show that main stakeholders in demolition waste management chain include general contractors, professional demolition companies, transport companies, recycling plants, landfill officers, government departments and scavengers. Illegal dumping and low marketing acceptation of recycling products are two major barriers of demolition waste management. This study forms a concrete base for future studies aiming at optimizing the demolition waste management process.

Measuring the Degree of Rural Victims’ Satisfaction with Concentrated Rural Settlement in Post-disaster Reconstruction in China: A Conceptual Model

Developing concentrated rural settlement (CRS) in post-disaster reconstruction is considered as an effective means to achieve sustainable development and resilience by providing sufficient infrastructure and public services, more employment opportunities, and improved environmental quality. Several successful cases of developing CRS after 5.12 Sichuan Earthquake were reported. Existing studies have explored the critical determinant factors and decision model for developing CRS in post-disaster reconstruction in China at the macro level. However, few studies have been conducted to investigate rural victims’ feelings of CRS in post-disaster reconstruction at the micro level. As a result, it remains unknown whether CRS really benefit rural victims and where can be improved to deliver better CRS. The aim of this research is to put forward a conceptual model to measure the degree of rural victims’ satisfaction with CRS in post-disaster reconstruction in China. The logic and operation process of the conceptual model would be introduced. The conceptual model is helpful to guide data collection, data processing, and calculating the satisfaction degree in future. The result of satisfaction degree is useful to help identify the potential improvements on the CRS projects in post-disaster reconstruction in China.