A shift towards more structural applications for the stony fraction of C&DW requiring a higher quality/purity of the recycled aggregates is currently being investigated and promoted. Within the HISER project, technological solutions will be developed for the purification and quality assessment of recycled aggregates and the development of new products.
The vast majority (±95 %) of construction and demolition waste (C&DW) consists of stony materials, mostly concrete and bricks. A large proportion of this stony fraction can easily be recycled as aggregates within the construction sector, be it almost exclusively in low-grade unbound applications such as (sub)foundations. This market is however becoming saturated. Therefore, a shift towards more structural applications (requiring a higher quality/purity of the recycled aggregates) is currently being investigated and promoted. Within the HISER project, technological solutions will be developed for the purification and quality assessment of recycled aggregates and new products will be developed from the stony fraction of C&DW.
Through the integration and enhancement of automated sorting systems and selective electro-fragmentation, an upgraded recovery of the stony fraction from complex C&DW will be achieved. The smart combination of these new technological solutions will result in the production of three high-purity fractions (unbound aggregates; mortar; bricks and tiles) and impurities. Furthermore, these technologies will allow the automated segregation of recycled aggregates contaminated with hazardous substances (e.g. mineral oil, heavy metals). In addition, the development of novel inline automated quality assessment systems (based on Laser Induced Breakdown Spectroscopy, LIBS) will provide potential users with higher levels of certainty about the quality of the produced secondary raw materials. This will facilitate the market uptake of larger amounts of recycled raw materials in high-grade applications. In order to analyse the quality of the recovered materials subjected to the novel treatments, revised procedures for the characterization of recycled aggregate constituents are being proposed within this Work Package. It will also constitute new knowledge aiming to influence and update European standards.
The higher quality of produced aggregates facilitates the development of new high-grade products through the partial replacement of virgin raw materials with higher amounts of upgraded C&DW. The HISER project aims at lowering the demand for virgin raw (fine and coarse) materials in bricks and structural concrete and lowering the CO2-footprint by the production of low-embodied energy cements. The implementation of these developed products will be demonstrated later in the project in several case studies.
Figure 1: Schematic overview of the planned technological innovations for the treatment of the C&DW stony fraction.
Jef Bergmans
VITO