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Keywords:

  • industrial ecology;
  • ore;
  • scrap sorting;
  • total material requirement (TMR);
  • urban mining;
  • urban tailings

Summary

In this study we introduce the concept of total material requirement (TMR) to quantify the quality of materials from end-of-life buildings. The TMRs for the recycling of materials (urban ore TMR [UO-TMR]) from four types of Japanese buildings ( Japanese traditional wooden structure [ JTWS], wooden frame with walls structure [ WFS ], reinforced-concrete structure [RCS], and steel-based structure [SS]) have been estimated and the trade-off between the increase in function of recycled materials such as steel made from scrap and the additional inputs of energy and materials required to create the increase in function were evaluated. Steel made from scrap, aluminum made from scrap, and road material are assumed to be recycled from steel products, aluminum products, and aggregate and cement concrete in the buildings, respectively. Case study analyses were carried out to determine the effect of recycling only aboveground materials compared to recycling both aboveground and subsurface materials. Also, the effect of varying the recycling rate of wooden demolition debris is determined.

The UO-TMRs of steel made from scrap range from 4.7 kilograms per kilogram (kg/kg) to 18.2 kg/kg. Urban tailings (unrecycled components) account for the greatest proportion of the UO-TMR of steel made from scrap, and the next largest contributor is the recycling process. In the case of aluminum made from scrap, the UO-TMRs range from 22 to 196 kg/kg, with the contribution of urban tailings generally dominant, and the second largest contributor being on-site demolition and shredding. The UO-TMRs of recycled road material range from 1.04 to 1.16 kg/kg and are similar for different recycling cases and types of buildings.