Development of frameworks for the management of materials procurement and construction waste for Nigerian contractors

Construction is one of the industries that contributes the largest waste on the environment, resulting in pollution and high cost of projects. The industry is faced with waste management challenges undermining its quest for sustainable development. Nigeria is a developing country that needs urgent waste management solutions in construction. Meanwhile, construction waste management practices in the industry are still inefficient, insufficient and poorly organised. However, there is a dearth of literature that provides frameworks to help contractors manage waste effectively. Further, despite that waste can be generated in all construction activities, the existing literature is mainly concerned with providing waste management solutions unilaterally, particularly in the design or construction stage. There is increasing awareness that effort should be made to consider waste management in multiple stages, particularly those with limited attention. Therefore, this study investigates the relevant materials procurement and construction criteria for effective waste management and evaluates the relative priorities of the attributes in contributing to waste minimisation. A quantitative research approach was adopted to achieve the research aim. A comprehensive literature review was used to generate four potential materials procurement criteria, including top management support for procurement, procurement clause, low waste purchase management, and efficient delivery management. Also, top management support in construction, construction clause, site waste management plan and low waste technique were identified as criteria for effective waste management in the construction stage. Additionally, twenty–two attributes were identified and clustered under the materials procurement and construction criteria, respectively. Then, experienced academic experts in construction verified their relevance and suitability in a survey. A questionnaire was designed, pilot–tested and subsequently distributed to experienced construction practitioners in Nigeria through an online platform. The quantitative survey data were analysed using Voting Analytical Hierarchy Process (VAHP) to determine the importance of the criteria and related attributes based on priority weights. The results of the local weights of the attributes revealed that accurate materials quantification, a take–back clause in suppliers’ agreement document, alliance with suppliers and just–in–time delivery of materials are the most important for effective waste management in materials procurement activities. At the same time, senior managers’ early commitment to waste minimisation, identifying recyclable materials, adopting prefabricated building components and making subcontractors responsible for their waste are the most important in the construction stage. Further, frameworks to assist Nigerian contractors in managing waste effectively in the materials procurement and construction stages were developed, drawing on the global weights of the attributes and the multi–criteria decision–making concept. The frameworks provided actions that contractors can take to implement effective waste management upon incorporating the criteria in their waste management practices and considering the attributes priorities categorised as high, medium and low. The study, therefore, concludes that positive relationships and cooperation between contractors, subcontractors and suppliers is a requisite for effective waste management in the Nigerian construction industry. This research has contributed to the existing body of knowledge by establishing integrated key criteria that can be adopted to implement effective waste management in materials procurement and construction stages. By recognising the waste management priorities and implementing the actions suggested in the frameworks, Nigerian contractors can substantially minimise waste due to ineffective and unorganised materials procurement and construction activities in collaboration with suppliers and subcontractors. Considering the current waste management challenges confronting the Nigerian construction industry, the study recommends partnership and commitment between contractors, subcontractors and materials suppliers and a top–down management approach for effective waste management in the industry.