Semi-selective demolition: current demolition practices in Flanders

Construction and demolition waste (C&DW) represents one of the EU's largest waste streams. Eurostat (2010) estimates a C&DW generation of 970 Mton/year in the EU-27 (±2 ton/inhabitant), with an average recovery rate of 47% [1]. To reach a higher recycling rate, higher-purity material streams from C&D works are required. These can be obtained by a better sorting at the source, i.e. selective demolition.

We performed 5 demolition case studies in Flanders to assess the opportunities and challenges of selective demolition processes, both on industrial and residential buildings. Furthermore, a new quality management and traceability system, developed by Flemish construction confederation VCB, was tested in 3 of these case studies. This monitoring system aims at the certification of waste streams that originate from selective demolition. For the different case studies, different bottlenecks and best practices were defined.

In these case studies, the selectivity of the demolition is driven by the economic incentives of the Flemish market (high landfill fees and differential gate fees at recycling plants) and obligations from Flemish/Belgian legislation (e.g. mandatory elimination of asbestos and other hazardous materials). These incentives make “semi-selective demolition” current practice in the Flemish region. We define semi-selective demolition as a demolition work where the demolition company selectively collects all hazardous substances and that part of the non-hazardous substances that would overly reduce the quality of the stony fraction. The selective collection of the latter is determined by their value, the acceptance policy of the crushing installations of the stony fraction and by the time consumed for selective removal.