A British-made calcined clay aimed at reducing the carbon footprint of cement will be launched to the wider construction industry on Thursday 22 October.
CemBlend, the product’s manufacturer, will use the Precast and Masonry Expo to reveal a commercial partnership with Hepworth Clay to distribute HepCem, a calcined clay product manufactured at Hepworth’s Crow Edge site, near Sheffield.
HepCem is a pozzolanic material that can replace between 20% and 35% of Portland cement in concrete mixes.
By reducing clinker, the most carbon‑intensive component of cement, the product can help lower embodied carbon in cement and concrete, providing an alternative to more established supplementary cementitious materials (SCMs) such as ground granulated blast‑furnace slag (GGBS) and pulverised fuel ash (PFA).
The material has received independent certification from Construction Products Certification, confirming conformity with the British standard BS 8615-1:2019+A1:2026. It includes ongoing factory production control surveillance and sample testing at Hepworth’s site intended to reassure cement and concrete producers about consistent quality and performance, the firm said.
HepCem can be used in a variety of blended cement and concrete systems, including ternary and quaternary mixes that combine calcined clay with limestone, GGBS or PFA.
It can be added at the batching plant and applied in cement combination routes under BS 8500, the specification for concrete in the UK, subject to the relevant requirements.
Hepworth points to potential durability benefits from the material, including reduced permeability, improved resistance to chloride ingress and sulphate attack, and mitigation of alkali–silica reaction (ASR). These outcomes will depend on specific mix designs and exposure conditions, the firm said.
HepCem is produced from purpose‑selected clay that is calcined under controlled industrial conditions to deliver predictable pozzolanic activity.
CemBlend, which specialises in bespoke powder blending and the supply of emerging SCMs, will make HepCem commercially available at scale and offer blended products incorporating the clay.
CemBlend director Simon Boulter said: “HepCem is a great example of British manufacturing innovation. It has enormous potential to help reduce carbon emissions, provide an alternative to increasingly constrained supplies of traditional SCMs and strengthen UK construction supply chains.
“Calcined clay is gaining real traction in the UK construction industry, and we’re delighted to be unveiling our partnership with Hepworth Clay at the Precast and Masonry Expo.”
He added: “It is the perfect opportunity to introduce HepCem to an industry that’s actively looking for practical ways to reduce its carbon footprint.
“And crucially, this isn’t a product that’s still on the drawing board. The material is certified, our partnership is in place and HepCem is available at scale now.”
Hepworth Clay chief executive Daniel Hannappel said: “Hepworth has more than a century of experience in selecting, processing and firing clay, and that expertise is at the heart of HepCem.
“It’s a material engineered from purpose-selected clay under carefully controlled conditions, so producers can rely on consistent quality and predictable performance in every batch.
“We’re pleased to be working with CemBlend, whose expertise in bespoke blending opens up even more ways for producers to use HepCem. The more routes we have into the cement and concrete sector, the faster the industry can start cutting carbon with it.”