Cawarden Champions Circular Construction at Brooksby College

Project name: Tilbury Douglas at Brooksby College

Customer: Cawarden

Duration: September 2025

Sustainable innovation from the ground Up

From the initiation of the Tilbury Douglas project at Brooksby College, Cawarden was determined to ensure that sustainability and low-carbon material choices were embedded from the very outset.

“We believe that how you build is just as important as what you build,” said Mitch Townsend, Civils & Groundworks Manager at Cawarden. “That’s why, as part of our civils and groundworks package for Tilbury Douglas at Brooksby College, we made a bold decision early on - to replace traditional virgin aggregate with Eco Type 1 IBAA — a certified recycled material derived from incinerator bottom ash and supplied by Johnsons Aggregates & Recycling Ltd.”

Performance-led results

This wasn’t a fallback, it was a strategic, performance-led decision that delivered measurable environmental and operational results:

IBA Aggregate has a typical compacted bulk density of 2.1 tonnes per cubic metre when compared with quarried limestone that typically has a compacted bulk density of 2.4 tonnes per cubic metre. This means that you require 13% less IBA Aggregate for your projects. By choosing locally supplied Eco Type 1 IBAA Cawarden also reduced transport emissions. Alongside this, Cawarden not only reduced the project’s carbon footprint but also strengthened community supply chains and demonstrated that recycled materials can perform to, and even exceed, industry standards.

Laying the foundations for circular construction

Embedding sustainability into the material selection process from day one enabled Cawarden to create durable sub-base layers that support heavy construction plant, enhance programme certainty, and set a new benchmark for circular construction within the education sector.

“A fantastic project that shows just how versatile Johnsons Eco Type 1 IBAA Limestone Blend is,” said Sarah Bryan, Territory Sales Manager at Johnsons Aggregates & Recycling. “We’re really proud to have collaborated with Cawarden on this project and to be their chosen aggregates supplier for IBAA.”

Outcome

Through proactive decision-making and collaboration, Cawarden and Johnsons Aggregates have demonstrated how sustainable materials can deliver both performance and environmental benefit. The Brooksby College project stands as a leading example of how construction teams can drive meaningful change by rethinking traditional practices and embracing circular solutions.

Watch the project in action here

If you're exploring low-carbon alternatives or want to learn how our manufactured IBA aggregates meet technical and regulatory standards get in touch