The washed fines aggregate manufactured by Castle Environmental has successfully satisfied the End of Waste criteria for use as an aggregate replacement in bound precast concrete products.
The washed fines aggregate is produced from the processing of Air Pollution Control residues (APCr) generated from municipal waste Energy from Waste facilities.
Although the market for aggregates produced from other thermal process residues is well developed, APCr have historically been less likely to be processed for re-use due to the concentration of soluble species which would be detrimental to cement matrices. However, the novel and unique proprietary process operated by Castle Environmental removes these soluble species and produces a fine material suitable as a replacement aggregate.
The recycling of APCr not only replaces virgin materials in the production of concrete products but also diverts APCr from landfill in accordance with the requirements of the waste hierarchy. Significant quantities of APCr are still disposed of to hazardous landfill by reliance on temporary derogations to the Waste Acceptance Criteria. The precise timing of removal of these derogations is currently under review by DEFRA with one of the key considerations being the availability of alternative management techniques. The satisfaction of End of Waste criteria supports the prompt removal of such derogations.
Castle Environmental along with sister company Castle Construction Products is investing in additional production facilities to further increase APCr process capacity and concrete product ranges.