Construction & demolition waste (C&DW) is one of the largest waste streams in Europe. In Flanders, almost all inert C&DW is recycled as aggregate for use in foundations for road works. More and more, this way of working is considered as ‘downcycling’, since some value of the original materials is lost. There is a growing demand to stimulate ‘higher value’ use of these aggregates in more demanding applications, e.g. the use of recycled concrete aggregate in new concrete, or old bricks as resource for new bricks.
Besides recycled aggregates coming from inert debris, many industrial by-products and waste streams (slags, ashes, …), also find their way to the construction sector, and solutions are developed for use of other C&DW streams like cellular concrete, gypsum, insulation materials, … in new construction applications. If more than one application or treatment method for a waste stream is available, the question can be raised which of the recycling options is ‘the best’ or the most interesting, or offers the most ‘value’.
In order to be able to stimulate specific applications of secondary materials in the construction sector, a clear evaluation method is needed to define to which level an application of a recycled or secondary aggregate can be considered as ‘high value’ or, on the other end of the spectrum, ‘undesired’. Therefore, BBRI has developed for OVAM, the Flemish Authority for Waste Management, an assessment framework for secondary materials to be applied in the construction sector, in order to quantify the degree to which an application is ‘high value’ and contributes to a more circular economy.
Based on a literature review and a sector consultation, a two-step approach is proposed. The first assessment takes into account several aspects broadly defining the ‘high value’ for a certain combination of resource in an application: economic impact, practical and technical implications of the application, environmental impact and benefits, and local and regional effects. For each axe, several indicators are described.
In the second step, focus is put on the environmental benefits and impacts of the different recycling options for one waste stream. These options are quantified using an LCA approach, based on EN 15804. Via scenarios, the impacts of waste processing up to the end-of-waste point, in module C, and benefits and loads beyond the system boundary (occuring after the first life cycle) in Module D, are quantified. This approach allows to take into account the transport distances, energy consumption, avoided resource extraction & use, changes in production processes and thus all associated impacts and benefits of using the recycled material instead of the usual resources.
Finally, a case studies are elaborated, to verify the feasibility of this approach, and to give some insights on further work to implement this method in (Flemish) practice.
Proof of compliance - requirements and quality assurance , LCA and emission modelling , Regulations and legislation
