On-site concrete waste minimisation in Iran

Construction waste minimization and management plays an efficient role in achieving sustainability by providing appropriate consideration to the environment, community, and social conditions by delivering built assets. The construction industry has a significant effect on the environment in terms of resource consumption and waste production. Recent statistics published by the UK Government disclose that the construction and demolition sector generates approximately 32% of the total waste in the UK, which is three times more than the waste generated by all households combined. Concrete has been a leading construction material for more than a century. However, current and on-going studies in the field of construction waste minimization and management mostly focus on general waste management or examine one specific method of waste minimization. While only a limited number of studies have been conducted to examine on-site concrete waste minimization, the literature reveals that research in this context is required. This research aimed to propose an on-site concrete waste minimisation framework (OCWMF) for construction projects, which could potentially be applicable and achievable in Iran. In this pursuit, six objectuves were determined to guide the research, which are: to identify the common methods on OCWM in the UK as a successful pattern in WM; to rank OCWM methods in UK; to rank OCWM methods in Iran; to identify the differences between common methods of OCWM in the UK and Iran and explore the possible causes of these differences; and to investigate the causes of differences in the favoured methods in the UK and the favoured methods in Iran. Finally, the last objective was to propose a framework for Iran. Both quantitative and qualitative strategies as well as a combination of qualitative and quantitative strategies were adopted for this research. Data was collected through face-to-face semi-structured interviews in the UK (N=5), a self-administered postal questionnaire survey in the UK (N=196 distributed, N=73 received), a self-administered postal questionnaire survey in Iran (N=196 distributed, N=110 received), and face-to-face semi-structured interviews in Iran (N=10). Interviewees were project managers, site superintendents, consultants, and engineers selected from the top 100 contractor companies and the top 100 consultant companies in the UK and in Iram. The questionnaire questions were developed on the findings of the literature review and the semi-structured interviews in the UK. Then, to examine the outcomes of interviews in Iran, three case studies in Iran was observed. Finally, emanating from study results, an OCWMF was developed and refined using discussions (N=2), a questionnaire (N=6), and interviews (N=7). Key findings that emerged from the study include: legislation and regulations in the UK are the main drivers for construction waste reduction; governmental initiatives in reducing waste, use of pre-fabricated building components, and education and training are the most recommended OCWM methods in the UK in terms of overall worthiness or spending to create savings or minimize waste; governmental incentives to reduce waste, education and training, and purchase management are the most recommended methods in Iran; the main differences between proposed OCWM methods in Iran and in the UK are in the use of pre-fabricated concrete elements (PCEs) and ready-mix concrete; the cost of using PCEs in the main cause of difference in methods between the countries; and the consultants and contractors involved in the case study were not interested in using PCEs in their projects due to the high costs involved despite the significant reduction in waste when this method is used. In conclusion, the framework proposed various remedies that could potentially be used for improving OCWM in Iran. This study has also made some recommendations for the industry, policy makers, and for further research. The content should be of interest to contractors, clients, and engineers.