ABSTRACT
In Hong Kong, a huge quantity of construction wastes is produced every day representing a large fraction of the total solid waste stream. Construction wastes are normally composed of concrete rubble, brick, tile, sand, dust, timber, plastic, cardboard, paper, and metals. The disposal of the wastes has become a severe social and environmental problem in the territory. Government sources have indicated that there is an acute shortage of landfill space in Hong Kong as Hong Kong’s landfills are expected to be full within 6-10 years’ time (CEDD 2007). To tackle this problem, the Government has introduced a construction waste charging scheme to encourage waste producers to minimize wastage and recycle reusable materials from the waste stream. Under the scheme, Government has set up sorting facilities to separate the inert portion of the construction waste (rock, rubble concrete, asphalts, sand, brick, tile etc) from the non-inert portion (i.e. paper, timber, bamboo, plastic, metals). It should be noticed that the characteristics of the sorted construction waste is significantly different from that of crushed concrete rubbles that is mostly derived from demolition waste streams. The latter, after appropriate crushing and sieving, can be reused
as recycled aggregates in various forms of construction. The sorted construction waste, however, can at best be regarded as a low-grade recycled aggregate. This is due to the presence of higher percentages of non-concrete components (e.g. soil, brick, tiles etc) in the sorted construction waste. In the past, this “inert” portion of the construction waste was reused for reclamation projects. But the recent public objections to public filling have greatly reduced this disposal outlet. The possibility of recycling these wastes in the construction industry is thus of increasing importance. In addition to the environmental benefits in reducing the demand on land for disposing the waste, the recycling of construction wastes can also help to conserve natural materials.
