Research On The Process Of Demolition Waste Management From The Perspective Of Carbon Emission

The acceleration of urbanization has promoted the increasing number of demolition and renovation projects, and demolition waste has been the major component of construction waste. At the same time, currently active demolition activities run in opposite direction to the idea of low-carbon cities and sustainable development. Therefore, this study examines the process of demolition waste management from the perspective of carbon emissions and identifies the main sources of carbon emission. Besides, it lays solid foundation for the optimization of demolition waste management process and improvement of waste management measures in the future.Through literature review and field research, the life cycle of demolition waste is defined as a series of related process, which consists of building demolition phase, site management phase, transport phase and disposal phase. On this basis, this study investigates the demolition activities and waste recycling process and hackles the sources of carbon emission. Then it takes a real demolition project in Shenzhen as an example and calculates its carbon emissions from each input and the aggregated emissions, by inventory analysis and appropriate selection of carbon emission indexes.Results show that the carbon emissions in building demolition and site management phase account for half of the total, which are the main stage during the whole management process. Recycling process occupies one third of total carbon emissions. And the transport phase takes the smallest proportion of carbon emissions, which is less than 7%. In the building demolition and site management phases, internal combustion air compressor, hand hammer drill and crawler hydraulic crusher are the main equipment emitting greenhouse gas, which should be used in a limited way. While in transport phase, nearly 80% of carbon emissions come from the energy consumption of transport vehicles. And in the process of waste recycling, concrete crusher in crushing production line and block molding equipment in brick production line is the most important source of carbon emissions in their production line, respectively. As to landfill process, carbon emissions from waste itself during landfill occupies the most proportion, which is nearly 70%. Therefore, it is an effective way for reducing the carbon emission in this phase to minimize the landfill amount of demolition waste or increase its recycling rate. From the perspective of carbon emission rate in various phases, when landfilling one ton of waste in landfill process, 6.19 kg greenhouse gas would be emitted, which is higher than any other phases. It is followed by the demolition and site management phase, which release 5.37 kg greenhouse gas when one ton of waste is generated. And the carbon emission rate of recycling process and transport phase is only 4.06kg/t and 0.80kg/t, respectively. Consequently, if carbon emissions factor is considered only, recycling is the better disposal way than landfill. Nevertheless, viewing from the whole life cycle of building, the proportion of greenhouse gas emissions from demolition waste management stage is still very small, which is less than 13% of the total, and that is less than building construction stage, as well. By comparison, the embodied stage of construction materials emits the most greenhouse gas, which accounts for more than three quarters of the total carbon emissions during the whole life cycle. Accordingly, more attention should be paid to the enhance of mining technology of construction raw materials and material production process, if the reduction of carbon emissions from life cycle of building is intended to be achieved.