Prediction Of Urban Housing Construction And Demolition Waste Production Based On Material Flow Analysis

After the reform and opening up,the development of China’s three major industries accelerated,and a large number of rural people flocked to cities,which promoted urbanization and generated a large demand for urban housing building.This has led to continuous outward expansion of cities and corresponding building renewal and renovation on existing urban plots to accommodate and meet development needs.However,the frequent and large-scale house construction and demolition activities generate a large amount of construction and demolition waste(C&DW).The traditional disposal methods not only encroach on a large amount of valuable land resources,but also have some potential environmental safety hazards.Therefore,it is of great importance to estimate and predict the changing trend of C&DW production in a scientific and reasonable way,to understand scientifically the impact of urban C&DW on the environment,and then to formulate practical C&DW management strategies and system planning schemes.This thesis firstly conducted literature research and data research on research methods related to C&DW production,building service life,material substance use intensity,material loss volume,and building structure change trends,and analyzed the C&DW volume and its material composition generated during construction and demolition of urban residential and non-residential buildings.Secondly,with reference to the research methods and ideas of construction demand-driven new construction and demolition activities,relevant parameters(population,urbanization rate,per capita floor area,etc.)were fitted.Finally,long-term prediction and systematic analysis of the spatial and temporal variation characteristics of the scale of construction and demolition activities,C&DW production and material composition in 31 provinces and cities in mainland China were conducted based on the dynamic material flow analysis method.The results of the study indicate that:(1)The eastern region has the largest scale of new residential and non-residential building area,and its growth rate and decline rate are the fastest,followed by the central and western regions,and the northeast region is the last.Under the low,medium and high scenarios,the overall trend of new residential building area in each region is to increase before decreasing.The peak in residential and non-residential new construction area in the three scenarios occurs earliest in the east,around the 2020s,slightly later in the central region,and latest in the western region,around the 2030s,while it peaks earliest in the northeast region,around the early 2020s.The overall trend of urban residential and non-residential building demolition area in each region shows an increase followed by a gradual decline,and there are significant differences in the trends of building demolition area changes among the regions in the three scenarios.Under the low scenario,the area of residential and non-residential building demolition area in all regions almost peaks around2100.While under the medium scenario,the peak of house building demolition area occurs around 2080 in the eastern and northeast regions,in the central region in the early 2080s,and in the western region in the late 2080s.Under the high scenario,the area of housing building demolition in all regions maintains a high growth rate and a large scale,with the peak area of residential and non-residential building demolition in the Northeast region occurring earliest,both in 2066.The eastern region is slightly later,with peak residential and non-residential building demolition area occurring around 2066 and 2073,respectively.The central region is even later,while the western region has not yet seen an inflection point in the area of demolished urban housing buildings.(2)The trend of residential and non-residential C&DW production in each region is similar to the trend of its building demolition area,as C&DW mainly originated from demolition activities after 2000.The eastern region has the largest urban housing C&DW production,with the peak occurring in the 2070s to 2080s,while the central region has the second highest C&DW production,with the exception of Henan,which has not yet reached its peak,and the other provinces,where the peak of residential and non-residential C&DW occurred in the 2070s.The overall C&DW production in the western region(except Sichuan province)is smaller than that in the central region,and most provinces and cities have not yet reached their peak of C&DW production.The Northeast region has the lowest C&DW production of all regions,with its peak of C&DW production occurring around the 2060s.The main components of C&DW for both residential and non-residential buildings are concrete,bricks,and steel,and the proportion of these components in non-residential C&DW is slightly higher than that of residential C&DW.Concrete accounts for 41.5%to77.3%,bricks for 11.4%to 54.4%,and steel for 0.7%to 4.3%.(3)There are significant differences in the amount of C&DW produced and the area of land occupied under the different scenarios.Under the low scenario,the provinces and municipalities generate the lowest amount of C&DW and occupy the least amount of land.The high scenario has the highest C&DW production in all regions,approximately double the highest C&DW production in the low scenario.The medium scenario is more moderate in terms of C&DW.On a national scale,the eastern coastal regions,the central regions and the western provinces of Sichuan and Guangxi Zhuang Autonomous Region have higher C&DW production and occupy a wider land area.Among them,Guangdong,Henan,Shandong,Hebei and Jiangsu have the largest land area occupied by C&DW,and their largest occupied land areas ranging from 15.67 to 29.55 km~2,13.34 to 26.35 km~2,12.07to 23.01 km~2,11.07 to 20.41 km~2 and 10.87 to 20.54 km~2 under the three scenarios,respectively.Overall,this thesis,based on extensive literature and data research,combined with the material flow analysis model on construction and demolition flow and construction and demolition waste generation characteristics and other related research and main results,can provide basic datas for the systematic management of C&DW and provide methodological references for regional or national scale C&DW production forecasting methods.