**3. Methodology**

This study used data from the Science Direct and Web of Science database during the years 2019–2021 to explore research published in journals, books, chapters, and studies on the sustainable construction industry. The main keywords to search the database included construction industry, sustainable waste management, sustainable C&DWM, challenges, barriers and obstacles to sustainable C&DWM, management of C&DW in developed and developing countries, Egypt, Ghana, UK, and KSA, statistical analysis, relative importance (RI), proposed solutions to eliminate and overcome barriers to sustainable construction, etc. The papers included in this study were published between the years 1998 and 2021. This was done to identify barriers to sustainable C&DWM in some developed and developing countries as well as to investigate the possible solutions to tackle the barriers. The initial search yielded more than 300 publications in the English language. They were analyzed individually to assess if they focused on sustainable C&DWM in developed and developing countries. Thus, general and non-relevant articles were excluded from these articles. At the end, a total of 78 research items has been retained including 77 research articles and 1 technical report.

The methodology of the study consists of three main steps: In the first step, identify the barriers based on the literature review. In the second step, the questionnaire was assessed by experts in construction projects. In the third step, the reviewed questionnaire was sent to respondents to identify and rank the barriers. Ranking of the barriers was carried out using the RI, and the results were statistically analyzed using Statistical Package for Social Sciences (SPSS). Practical solutions were proposed to overcome the identified barriers. Figure 1 shows the methodology for the current research.
