Balance theory for recycling of construction and demolition wastes

The key to reduce construction and demolition wastes (C&D wastes) lies in finding a way to make them valuable. Recycling of C&D wastes into profitable commodities is one of the effective means. Balance of the supply of C&D wastes and the demand of recycled C&D waste products (Balance Theory) is recommended in new developments. The maturity of Balance Theory requires gradual establishment of recycling facilities. These facilities are capable to accept and handle not only inert materials but also other C&D wastes like wood and wood products, cardboard, metal, plastics etc. The Balance Theory rouses construction workers to adopt the idea of reduction of wastes. They are educated to clean their working places constantly and collect all construction wastes they generated into separate collection spots within the construction site. The site management personnel is required to establish site facilities and set up conditions in employment contracts and subcontracts for workers and subcontractors to follow. The culture of separating wastes at sources must be established and widely adopted so that Balance Theory could be realised. All in all, Balance Theory advocates the amount of wastes generated from a construction project and sent for recycling process must be equivalent (or proportional) to the amount of the recycled C&D products imported and used as construction materials for that project. Evaluation of the Balance Theory can be extended to a group of developments within a district or even augmented to a city as a whole. Zero C&D wastes sent to landfill may be too idealistic, however, minimisation of C&D wastes could be realised if Balance Theory is enforced. Appropriate actions taken by the Government may be needed to encourage the execution of the Balance Theory when recycling facilities and the green working culture of construction participants are well developed. Balance Theory can be first carried out in government projects as pilot scheme. The proportion of imported and exported amount of C&D wastes be reviewed and adjusted to suit the adoption and development of the Balance Theory.