Product · Materials Science
Product · InnDex 62 · Evidence provided · High specification risk
In-situ concrete with 30% calcined clay + 20% RCA, delivering 66.6 kgCO₂e/m³ savings.
A combined-substitution concrete mix (C32/40–C40/50) deployed in-situ as permanent structural RC beam, replacing Portland cement with calcined clay and virgin aggregate with recycled concrete aggregate in a single pour. Addresses embodied carbon and virgin resource demand in structural concrete. Validated through a four-party trial (McAlpine, Heidelberg Materials, Getjar, AKT II) at London Museum with 14-day concept-to-cast cycle.
This is a dual-substitution structural concrete — Portland cement partially replaced with calcined clay, virgin aggregate partially replaced with recycled concrete aggregate — poured in situ as a permanent RC beam at the London Museum by a four-party team including McAlpine, Heidelberg Materials, and AKT II, with the whole cycle from concept to pour compressed to 14 days. The headline number is a quantified 66.6 kgCO₂e/m³ reduction on a C32/40–C40/50 structural mix, which puts it in the sharper end of the low-carbon concrete evidence set. With a single in-situ pour behind it, this is genuinely encouraging pilot evidence — but it is one project, one contractor team, one geography, and confidence in scalability across different sites and supply chains has not yet been established. The calcined clay thermal treatment carbon footprint is not independently disclosed, which matters to any whole-life accounting exercise, and neither the combined binder's long-term durability in UK weathering environments nor the quality-control protocols for dual substitution are yet standardised in UK building codes. Worth tracking closely for structural projects with carbon targets, particularly where the same collaborative supply-chain model can be replicated — but the specifier should treat the 14-day cycle and the CO₂ figure as evidence of what the best-case looks like, not the industry standard yet.
Single in-situ pour documented with quantified embodied carbon saving (66.6 kgCO₂e/m³ vs. baseline); mix design and mechanical compliance (C32/40–C40/50) reported but no independent third-party certification, durability data, or long-term performance monitoring disclosed in source. 'UK first' claim is accurate for the combined approach but marketing-qualified; calcined clay use in UK is not novel. Source is trade publication; no peer-reviewed or structural engineer's signed-off durability assessment found. Team credentials are strong (AKT II, Sir Robert McAlpine), lending credibility, but single project does not constitute scale deployment. No data on cost premium, mix robustness across batches, or site variability.
#calcined clay #RCA #embodied carbon #in-situ concrete #low-carbon cement #circular economy