*3.1. Identification of Barriers*

There are so many barriers that hinder the effective and sustainable implementation of waste management policies and strategies in construction projects. In the first phase, 82 papers were reviewed and eleven barriers were identified; later, 24 papers were reviewed and the selected barriers were the same. This is due to the overlap of suggested barriers investigated through the reviewed papers, as well as experts' recommendations, as indicated in Table 1. All these barriers are widely acknowledged in the literature and are

highly applicable in the current context of this study. The literature review focused mainly on two criteria for journal selection: indexed in Science Citation Index and a publication focusing on waste management.

**Table 1.** Barriers to effective C&DWM.


**Figure 1.** Research methodology scheme.

B1: Institutional Fragmentation.

Several institutions are involved in waste management, and as often as it is the case, many of these institutions reneged on their responsibilities, hoping other institutions would tackle the problem. This scenario occurs mostly under extensive bureaucracy where there are no clearly defined lines of responsibilities [2,46,47]. Institutional fragmentation is particularly a major challenge to effective and sustainable C&DWM, and rather than a weak and bureaucratic waste management system, requires effective and strong institutional arrangements for waste management [4,41,63,64].

B2: Lack of Fundamental Data on C&DW.

Sustainable waste management requires reliable data on rates of generation and composition of the wastes. However, the fundamental data on C&DW that will inform effective planning for sustainable C&DWM is absent in many developing countries and woefully inadequate in some developed countries [27,51,52]. Notwithstanding this, C&DW comprises the largest waste stream in most developed countries and is also increasing at alarming rates in the developing world, due to an increasing rate of urbanization [65].

B3: Lack of Law Enforcement.

Many countries have a long history of safeguarding the environment, including attempts in ensuring proper C&DWM, and have enacted appropriate legislations; nonetheless, the enforcement of legislations is a major challenge in many countries, particularly in developing countries [41]. The non-compliance and non-enforcement of laws and regulations governing C&DW have significantly contributed to poor C&DWM in many countries [2,30,41,54].

#### B4: Insufficient Attention Paid to C&DWM.

Stakeholders in the construction industry usually focus more on completing the project within budget, at the expected time, and to the desired quality, and much less attention is paid to the waste emanating from construction activities [15,27,33,66]. This has given a bad image to the construction industry, as improper disposal of C&DW results in far-reaching environmental consequences [2].

#### B5: Socio-political factor.

The construction industry, like other industries, is characterized by cultural and socio-political differences across firms' types, age, and size. Consequently, several studies have linked the construction industry's culture with its waste intensiveness [1,10,21,52,67]. This means that an effective and sustainable waste management system cannot be established unless the cultural and socio-political patterns of construction firms are fully understood [25,46,53,57].

#### B6: Technological.

The C&DW technology and management choices in many countries have become very complicated, especially when reductions in greenhouse gasses, elimination of landfill sites, and land reclamation are targeted goals [42,44]. The C&DW sector has become a specialized industry involving huge and indivisible capital requirements, and sophisticated technology, requiring in-depth experience and expertise in research and engineering [26,30,43–46,51,57]. Technical information and guidance, advanced technologies and methodologies for sustainable construction represent important requirements for effective C&DWM [1,20,52].

#### B7: Lack of Regulation.

Environment regulation, including C&DWM, is essential for ensuring effective and sustainable environmental management and governance [1,2,10,21]. However, weak enforcement of environmental regulations in many countries allows construction firms to flout regulations on C&DWM without sanctions [50,51,55].

#### B8: Financial.

Financial resources are critical for effective waste management; however, these are generally scarce in many countries [25,44]. Poor economic policies, coupled with extreme poverty and infrastructure deficit, make the financial consideration one of the obvious constraints to developing appropriate C&DWM systems in most developing countries [1,10,26,43,52,68].

#### B9: Human Resources Constraints.

Human resources are essential for effective waste management, especially the daily operations of C&DWM [2,52]. Nonetheless, many countries do not have the human resources with the requisite expertise required for the effective and sustainable management of a C&DW system [25,27,30,42,54,55].

#### B10: Construction Project Characteristics.

Several construction project characteristics have the potential to influence C&DWM, which include: the complexity of the project, type of project, size of project, location of the project, the importance for the project to be completed on time, the form of contract, and project funding [27,46,53,60].

B11: Rigidity of Construction Practices

Many stakeholders are involved in the construction industry who play varied and crosscutting roles. The effectiveness of a C&DWM system in a particular location or country depends on the performance of these stakeholders in terms of their awareness of the impact of construction SW on the environment, and flexibility or rigidity in their practices [27,61,62]. With high public awareness about the problems posed by inadequate C&DWM, broad consultation and the involvement of all stakeholders are needed for the sustainable development of C&DWM strategies and policies [52,60].

#### *3.2. Data Collection and Analysis*

The questionnaire is a systematic technique of data collection and it is used to obtain professional opinions. A questionnaire survey was distributed amongst various stakeholders within different organizations to investigate barriers to effective waste management implementation in the construction industry in the selected countries. In this study, the construction industry in the studied countries was categorized in terms of ownership (public or private), type of the organization, size of the organization, role of the respondent in the organization, and experience of the respondent in the construction industry. A two-step procedure was adopted to assess its appropriateness and rationality. In the first step, the questionnaire was assessed by 15 persons having expertise in construction projects, to ensure clarity and technical applicability. In the second step, the reviewed questionnaire was sent to respondents to identify and rank the frequency (i.e., 1 = Never, 2 = Rarely, 3 = Occasionally, 4 = Sometimes, 5 = Frequently, 6 = Usually, and 7 = Always) of the eleven barriers.

The distribution was conducted across various countries, mainly the UK, the KSA, Ghana, and Egypt. Due to the ongoing COVID-19 pandemic, the Google questionnaire survey form was used. Around 150 experts in the construction field were invited to participate in the study and 93 responses were collected over the course of two months in 2020. A convenience sampling approach was adopted to select participants from each country; 93 valid responses were received and considered for analysis (UK: 18, KSA: 31, Ghana: 32, and Egypt: 12). All results were reported descriptively with the aid of Statistical Package for Social Sciences (SPSS), Microsoft Excel, and RI.

The study adopts the RI research method to identify and rank the critical barriers to the sustainable implementation of construction demolition waste management in the countries investigated. The RI is widely used in the analysis of construction strategies and policies. Equation (1) [69,70] depicts the RI measurement.

$$\text{RI} = \sum \text{(ax)} \times \frac{100}{T} \tag{1}$$

where: a = constant (weight) 1 to 7, x = *n*/N, *n* = Frequency of responses, N = Total responses.

Finally, the questionnaire included the reasons for organizations' engagement in effective C&DWM. It was investigated by asking the respondents "Why do you think your organization should engage in effective C&DWM activities?" This was performed to know the current trends and needs to achieve sustainable C&DWM in their organizations.

#### **4. Results and Discussion**

The results discussed under this section are based on the extensive literature review that produced the barriers to effective C&DWM and the responses to the questionnaire by experts from the UK, the KSA, Egypt, and Ghana. Thus, the responses of 93 experts in the construction industry are discussed.

#### *4.1. Categorization of the Construction Industry*

The classifications of respondents in relation to ownership of the organizations are shown in Figure 2a. It can be seen that 49.5% of the respondents were from the public sector, whereas 50.5% work in the private sector. Thus, both the public and private sectors of the economy were equally represented.

**Figure 2.** Categorization of the Construction Industry: (**a**) Ownership of the organization, (**b**) type of organization, (**c**) size of organization, (**d**) position in organization, and (**e**) years of experience.

Also, on the type of construction industry, a majority of the respondents (41.9%) were from consultancy firms and remaining respondents were contractors, clients, and other built environment professionals, as indicated in Figure 2b. These represent the main stakeholders in the construction industry of the four countries under study. Furthermore, Figure 2c indicates percentages of organizational size based on the number of employees. The organizations were categorized in sizes as: large organization (<249 employees), medium organization (50 to 249 employees), and small organization (>49 employees). The large size organization accounted for the highest percentage of respondents at 45.2% of all respondents.

In addition, the position of respondents in the organizations are classified in Figure 2d. Project managers recorded 32.8% of respondents, and the significance of this is that they were well placed to assess the barriers to an effective and sustainable C&DWM system. The classification of respondents according to the years of experience is shown in Figure 2e. The category of respondents with more than 15 years of experience stood at 34.4%, whereas those with 6 to 10 years' experience constituted 26.9% of respondents.

It can be observed from the characteristics of respondents that the majority are from consultancy firms, large organizations, project managers, and have considerable experience of the workings of the construction industry in their respective countries.

#### *4.2. Organizations' Engagement in Effective and Sustainable C&DWM*

The result on organizations' engagement in effective and sustainable C&DWM were obtained and illustrated in Figure 3. The most prominent reasons identified by 70% of respondents was the desire "to make a positive difference to society". This clearly shows that respondents are aware of the adverse environmental effects of construction activities on the natural environment, and the need for the industry to make a difference to society in the manners that it conducts its activities. Though not as significant, 15% of respondents hold the view that the primary objective of their organization's engagement with sustainable C&DWM is to meet the primary objectives of delivering quality projects timely and within costs.

**Figure 3.** Reasons for organizations' engagement in effective C&DWM.
