Prediction of construction and demolition waste production based on material flow analysis

In response to the rapid increase in the amount of construction and demolition waste (C&DW) and the lack of statistical data on the output of C&DW, based on the 1stOpt fitting platform and Visual Basic programming software, a dynamic prediction model of urban residential and non-residential construction waste was constructed, and the changing trend of C&DW production and its compositions under three scenarios of short lifetime, medium lifetime and long lifetime quantitatively simulated. The results showed that: The stock area of urban residential buildings and non-residential buildings in China would reach their peaks in 2058 and 2064, respectively, with the peaks of 65.74 billion m² and 56.94 billion m². Under the short lifetime, medium lifetime and long lifetime scenarios, the construction area of residential and non-residential buildings would reach their peaks in 2020s, and the demolition area would peak in the second half of this century. The total output of China’s urban residential C&DW would reach its peak in 2072, 2081 and 2100 under the three scenarios of short lifetime, medium lifetime and long lifetime, respectively, with peaks of 2.869 billion tons, 2.171 billion tons and 1.65 billion tons. Under the three scenarios, the total output of non-residential C&DW would reach peaks in 2077, 2084 and 2100, with a total output of 2.625 billion tons, 2.029 billion tons and 1.548 billion tons, respectively. Before 2000, C&DW was mainly composed of construction waste. After 2000, demolition waste was the main composition. By 2100, the proportion of demolition waste would reach 98%. Among them, concrete, bricks, and steel accounted for 44%-71%, 22%-51%, 0.50%-2.89%, and other compositions accounted for about 2.76%-4.68%. Taking into account the development trend of construction flow and the characteristics of C&DW generation, the government departments should slow down the growth rate of per capita building area through macro-control, prolong the service life of buildings, improve the recycling rate of C&DW and the market consumption of secondary buildings materials, so as to cut down the output of C&DW and reduce their damage to the ecological environment.