Circular Construction and the Next Generation of Aggregates
Circular Construction and the Next Generation of Aggregates
By Kaziwe Kaulule, Managing Director – Aggregates, Holcim UK
As the construction industry races to meet net-zero goals and deliver more sustainable buildings and infrastructure, specifiers are under growing pressure to ensure that the materials they choose meet both technical performance standards and carbon reduction targets.
With embodied carbon and circular economy practices moving up the agenda, Construction Demolition Materials (CDM) and other recycled aggregates are set to play a central role in future material specifications. But for recycled materials to be successfully integrated into the UK’s construction supply chain, specifiers need confidence in a number of factors: availability; quality; compliance; and long-term durability.
In this feature, I’ll explore how CDM is evolving, what it means for specification decisions, and how, as an industry, we can bridge the gap between practicality and sustainability.
According to DEFRA, construction, demolition and excavation (CD&E) waste accounts for the majority of industrial waste in the UK, with over 60 million tonnes generated annually. At Holcim UK, we see this not as a problem, but as a massive opportunity to close the loop on materials, reduce reliance on virgin resources, and dramatically cut embodied carbon.
However, for recycled materials like CDM to move beyond ‘secondary’ status and into mainstream specification, they must deliver consistent, high-quality performance. Specifiers need assurance that using recycled aggregates won’t compromise safety, durability or lifecycle costs.
To address this, we have invested in externally verified, high-quality recycled aggregates, such as those supplied under our Ecocycle brand, which includes rigorous certification and transparent documentation on recycled content and performance. This approach allows specifiers to confidently integrate CDM into both structural and non-structural applications, whether for housing, highways or major infrastructure.
Increasingly, public and private clients are demanding demonstrable reductions in Scope 3 emissions… and specifying recycled materials, verified to meet exacting standards, is a tangible way to contribute to those goals.
Balancing sustainability with practicality
Despite growing demand for sustainable options, there are understandable concerns among specifiers about availability and consistency. These concerns are valid. For circular construction to be scalable, supply chains need to be robust, transparent and predictable.
Part of the solution lies in closer collaboration across the demolition and construction sectors, with clearer links between those generating CDM and those specifying it in new builds. Our teams are actively working on building these connections, creating CDM hubs near urban centres where materials are generated, ensuring regional supply can meet regional demand.
Another key factor is certification and quality control. We are now leading industry-first innovations such as certified blended rail ballast with 50% recycled content, opening doors to new applications of CDM in complex, performance-critical environments like rail and infrastructure. These kinds of solutions demonstrate that recycled materials can meet high-spec demands, not just low-value fill or sub-base.
Furthermore, cost is often raised as a concern. But in many cases, the value of circular materials is in the carbon and environmental savings they deliver, increasingly essential in winning major contracts. Clients are asking specifiers to deliver on embodied carbon goals, and recycled materials are an essential part of that answer.
The future of specification
Looking ahead, regulatory pressures and client expectations are converging, creating a new landscape for specification. There is now a clear trajectory toward mandatory inclusion of low-carbon, circular materials.
Specifiers will need to navigate a market where material passports, embodied carbon disclosures and circularity data become standard parts of the specification process. The UK Green Building Council (UKGBC), the Construction Leadership Council (CLC) and emerging government guidance are all pointing to a future where reuse and recycling are not optional extras, but baseline expectations.
One of the clearest examples is the focus on Scope 3 emissions. As companies and clients work to reduce the indirect emissions embedded in their supply chains, the selection of verified recycled aggregates becomes a critical tool in hitting those targets.
Holcim UK is committed to helping specifiers navigate this shift by providing clear, data-backed material specifications that outline recycled content, embodied carbon savings and compliance with relevant standards.
Practical steps for specifiers
So what does this mean for specifiers making choices today? Here are some practical steps to ensure circular materials are part of your future:
Ask for verification: ensure recycled materials (including CDM) are backed by third-party certification and traceable supply chains.
Consider embodied carbon early: incorporate whole-life carbon assessments into project design and specification stages to identify opportunities for circularity.
Collaborate across supply chains: work with demolition contractors and materials suppliers early in the project to identify opportunities for reuse and recycling, rather than as an afterthought.
Keep informed on standards: stay up-to-date with emerging standards and specifications for recycled aggregates, which are evolving rapidly to reflect modern performance requirements.
Focus on value, not just price: consider the carbon, environmental and social value of using recycled materials, which increasingly form part of tender evaluation criteria.
Circularity is here to stay
Circular construction needs to become the new norm. But for it to succeed in this way, specifiers will need to play a critical role in bridging ambition and reality, ensuring that recycled materials are trusted, specified and used in everyday construction.
As we rebrand and step into a new chapter as Holcim UK, we are doubling down on our commitment to circular economy leadership, collaboration and innovation. We are ready to work with specifiers, demolition partners and customers to make circular construction a practical, scalable solution.
We are a leading provider of sustainable building solutions, committed to enabling greener cities, smarter infrastructure and improved living standards. We strive to make sustainable construction a reality and are actively working towards becoming net-zero before 2050 through our dedicated approach to decarbonisation, circularity and nature.With 200 sites and employing 4,000 people, our product and service range covers foundations to rooftops and includes aggregates, asphalt, building and landscaping, cement, contracting, mortars and readymix concrete. We are committed to collaborating with our customers and the supply chain to design and build better communities. Follow us on LinkedIn or at our website www.holcim.co.uk
About Holcim Group
Holcim is a global leader in innovative and sustainable building solutions with net sales of CHF 27.0 billion in 2023. Our 63,000 employees are driven by our purpose to build progress for people and the planet across our regions to improve living standards for all. We partner with our customers to offer the broadest range of advanced solutions, from sustainable building materials ECOPact and ECOPlanet, to our circular technology ECOCycle®, all the way to Elevate’s advanced roofing and insulation systems.
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