Hepworth has achieved independent certification for its HepCem calcined clay, confirming conformity with BS 8615-1:2019+A1:2026 for use as a pozzolanic material with Portland cement.

The certification, awarded by Construction Products Certification (CPC), applies to calcined clay manufactured by Canova Clay Limited trading as Hepworth at its Crow Edge manufacturing site in Sheffield. It covers its intended use as a component of concrete, mortar and grout.

Certificate of Conformity CP 00281 was authorised on 24 August 2026 following an initial assessment of Hepworth’s Factory Production Control, product type testing and manufacturing processes.

The accompanying CPC assessment concluded that Hepworth’s product conformity system met the applicable requirements and expected outcomes, with no corrective action required and no initial findings identified.

The certification represents an important step in the commercial development of HepCem, Hepworth’s purpose-produced calcined clay supplementary cementitious material developed to support lower-clinker cement and concrete systems.

For more than 40 years, Hepworth has produced calcined clay as part of the controlled raw material process used within its vitrified clay manufacturing operations. That established expertise in clay mineral selection, thermal activation and fine grinding has provided the foundation for the development of HepCem.

HepCem has been developed to give concrete and cement producers a reliable, UK-manufactured alternative to clinker. Its controlled production process is designed to provide consistent mineral composition, predictable reactivity and reliable pozzolanic performance, contributing to strong compressive strength development alongside the durability and consistency producers expect from modern concrete.

Daniel Hannappel, CEO at Hepworth, said:
“Achieving certification to BS 8615-1 is a significant milestone for HepCem and gives our customers independent assurance around both the product and the controls behind its manufacture.

“We have decades of experience working with clay materials and calcination, and HepCem allows us to apply that expertise to one of the most important challenges facing the construction industry: reducing the embodied carbon associated with cement and concrete.

“With certification now in place, we are ready to work with cement and concrete producers looking to evaluate calcined clay within lower-clinker formulations.”

HepCem can be used as a supplementary cementitious material within a range of cement and concrete applications and has been developed to support producers looking to reduce clinker content while maintaining the strength, performance, durability and consistency required from modern concrete.

The product is manufactured in the UK, supporting domestic supply chains while providing the construction industry with an additional source of supplementary cementitious material as established materials such as fly ash and GGBS face increasing supply pressures.

The BS 8615-1 certification is supported by ongoing surveillance of Hepworth’s Factory Production Control, conformity evaluation of auto control testing and audit testing of samples taken from the manufacturing location.

Hepworth is now actively engaging with cement producers, concrete manufacturers, specifiers and industry partners interested in assessing HepCem for use within lower-carbon cement and concrete formulations.

Further information, technical enquiries and product discussions are available at hepworth.co.uk/products/hepcem/.