Lignacite has become the first concrete block manufacturer to have the recycled content in its products independently verified by sustainability consultancy Blue Marble.

The verification covers over 90% of Lignacite's range, including the Lignacite ECO, Lignacite GP, and dense blocks, confirming the percentage of recycled material used in each.

This development aligns with the growing demand for verified sustainable materials in UK construction projects, including compliance with Section 106 Agreements and local initiatives such as whole life-cycle carbon reduction requirements in the City of London. Combined with Lignacite's Environmental Product Declarations (EPDs), which report the embodied carbon levels of its products from source to site, the recycled content verification provides architects and specifiers with an additional level of assurance when specifying materials.

Jacky Whiffen, SHEQ Coordinator at Lignacite's Nazeing site, said: "Every claim we make about recycled content is now independently verified. It wasn't a tick-box exercise. It was a detailed, three-and-a-half-month process that covered everything from site visits and materials trials to documentation, procurement and auditing. Our partners at Blue Marble went through it all – from how we source recycled sand and manage contamination risks to how much was used, when, and in which blocks."

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The verification confirmed that Lignacite ECO 50 and ECO 70 blocks contain 50% and 70% recycled content respectively, while Lignacite GP and dense blocks, including 7.3N and 10.4N units, now meet the 30% verification threshold. To achieve these levels, Lignacite sourced and trialled new recycled materials from local suppliers and conducted extensive testing to ensure the blocks retained strength, durability, and visual consistency.

Whiffen added: "We tested everything – different mix designs, moisture levels and how the blocks would behave in worst-case scenarios. Eventually, we found a reliable local source that now supplies our largest recycled material bay, holding nearly 2,500 tonnes. We've gone from using 300 tonnes a week to 2,500 – and we’re still pushing to go further."

To maintain verification integrity, auditing will be repeated annually for the first two years, then every three years thereafter. Each verification requires submission of detailed production data and on-site inspections to confirm recycled content levels are consistently maintained.

Sam McGarrick, Head of Advisory at Blue Marble, said: "This is the first time Blue Marble has verified recycled material use for a concrete block manufacturer – marking a new milestone in independently assured sustainability data for the sector. The level of rigour Lignacite applied to this process shows they’re serious about transparency and leadership in sustainable materials."

The initiative supports Lignacite’s broader sustainability goals, including a Net Zero target by 2030. Verification of recycled content is central to this plan, helping customers make credible sustainability claims without risk of greenwashing. Lignacite intends to extend verification to additional product lines as new materials become available.

Photo credit: Lignacite.