26th March 2021
A large material recovery operation recently took place at Redrow’s Allerton Gardens development in Liverpool, which saw more than 1,400 Tonnes of waste material processed into recycled aggregate.
The main aim of the 6-day long operation was to divert waste from landfill. The site had generated a large amount of concrete waste due to the removal of an existing road, which they needed to move in order to improve access to the new development. The road was underpinned with concrete slabs and these were excavated and formed part of the inert waste which was crushed during the recovery operation.
As well as concrete, other types of waste materials were also crushed and recovered, including waste bricks, blocks, tiles, ceramics, and excavated sandstone. The site team at Allerton Gardens had been stockpiling inert waste for a period of 6 months prior to the recovery operation, in line with Group Health, Safety & Environment Standards for Excavated Materials and Waste Legal Requirements, which states that inert waste should not be stored for longer than 12 months.
Allerton Gardens’ U1 Waste Exemption License means that the development is permitted to reuse the recycled aggregate which was produced from the processing operation. However, before any reuse takes place, the recycled aggregate will be tested in accordance with the WRAP Protocol for Recycled Aggregates to ensure it is of a suitable quality.
Using recycled aggregates in construction has environmental benefits, as demands on primary resources and virgin raw materials are minimised. This also results in carbon emissions savings, as material transportation distances are reduced. The site team plan to reuse the recycled aggregate in a range of settings, from creating private driveways and paths to patios and hard standings.
The recycling operation at Allerton Gardens resulted in a large amount of virgin raw materials being conserved. In addition to this, the division also benefitted from significant cost savings by reusing the recycled aggregate material. The cost of purchasing and importing a similar material would have been up to £12,600.
Chris Hayton, Project Engineer at Redrow NW who oversees the processes, said “These Recycling techniques enable us to extract the maximum value from materials. Wherever possible, we also try to maximise the lifespan of materials such as aggregates and surplus inert materials, by keeping them circulating in use for as long as possible.” This is in line with circular economy principals and demonstrates how Redrow and other housebuilders can make use of waste.
Elsewhere in Redrow’s North West region at Tabley Park in Knutsford, approximately 3500m3 of material was recently treated with lime in a process called lime stabilisation. Lime (a hydraulic binder) was incorporated into excavated spoil materials, which improved its workability and load-bearing characteristics. The processes turned unsuitable materials into suitable construction materials, which could have otherwise gone to waste.
As the global population increases and resources become more difficult and expensive to access, it is becoming ever more critical to find alternative means of sourcing and using materials. Through re-processing waste materials, Redrow is working hard to mitigate the amount of waste sent to landfill, as well as conserving energy and reducing greenhouse gases.
Image: a small portion of the feedstock for recycled aggregate at Allerton Gardens
Image: the finished product… Recycled Aggregate (14 mm to 10 mm)
Written by Olivia Ward (Sustainability Coordinator)