8Waste management in the building industry in Hong Kong has become an important environmental issue. 9Particularly, an increasing amount of construction and demolition (C&D) waste is being disposed at land-10 fill sites. In order to reduce waste generation and encourage reuse and recycling, the Hong Kong Gov-11 ernment has implemented the Construction Waste Disposal Charging Scheme (CWDCS) to levy charges 12 on C&D waste disposal to landfills. In order to provide information on the changes in reducinge waste 13 generation practice among construction participants in various work trades, a study was conducted after 14 three years of implementation of the CWDCS via a structured questionnaire survey in the building indus-15 try in Hong Kong. The study result has revealed changes with work flows of the major trades as well as 16 differentiating the levels of waste reduced. Three building projects in the public and private sectors were 17 selected as case studies to demonstrate the changes in work flows and the reduction of waste achieved. 18The research findings reveal that a significant reduction of construction waste was achieved at the first 19 three years (2006 -2008) of CWDCS implementation. However, the reduction cannot be sustained. The 20 major trades have been influenced to a certain extent by the implementation of the CWDCS. Slight im-21 provement in waste management practices was observed, but reduction of construction waste in the 22 wet-finishing and dry-finishing trades has undergone little improvement. Implementation of the CWDCS 23has not yet motivated subcontractors to change their methods of construction so as to reduce C&D waste. 24 25

5A considerable amount of solid wastes is generated every year from construction and demolition (C&D) 6 activities in Hong Kong. The C&D waste can be classified into inert and non-inert wastes, in which the 7 inert waste is normally disposed of in public fills as reclamation materials, and the non-inert part is dumped 8 at landfills. Under the current waste generation trend, all landfills and public fills in Hong Kong would be recycling. The findings also revealed that 40% of the survey respondents believed that waste reduction is 17 less than 5% after CWDCS has been implemented. The interviewees expressed that some waste generation 18 were unavoidable despite a waste disposal charge has been imposed. In addition, 30% of survey respondents 19 agreed that the cost of CWDCS was not high enough to raise the awareness on waste management on 20 construction sites.

Similar to many affluent cities found elsewhere in the world, Hong Kong is currently facing a great challenge to manage the wastes generated from its construction and demolition (C&D) activities that has wide-ranging impacts on the environment. To tackle this, the Hong Kong Special and Administrative Region (HKSAR) Government has signalled the required changes by sorting out the inert substances from C&D waste for reusing and recycling and using recycled building materials in construction through its role as both a construction client and contractor. The current practices and attitudes of local project participants towards C&D waste management were collected through questionnaires. A total of 69 questionnaires were received: 61% of the respondents stated that their projects did not take any measures to collect and separate C&D wastes and 64% of the projects did not use recycled building materials in construction. The prevailing problems of local construction industry are addressed through examinations of the constraints involved in improving C&D waste treatment and according to the results of the survey, to evaluate the practicability of increasing the capability and capacity of the industry to learn to be more sustainable.Construction and demolition waste, sorting, recycling,

Formwork is one of the most important temporary works for reinforced-concrete superstructures in building projects. The use of traditional timber formwork has dominated the construction industry in Hong Kong for many years. Now, however, low-waste technologies for superstructure construction are becoming more common. The study reported here compares the advantages and disadvantages of using traditional timber formwork and a large panel steel formwork system integrated with precast concrete semi-slab (composite formwork system) in superstructure construction in Hong Kong. The study compares these two different formwork systems used in two identically designed school projects in Hong Kong. The comparisons are focused on construction cost, time required for completion of work and construction waste generation. By conducting a detailed cost comparison, this paper shows that, despite the fact that the composite formwork system is able to produce less construction waste, the traditional timber formwork system is still more favourable economically. However, if the composite formwork could be reused in other standard school projects after completion of the project, economic advantages would be realised.

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