Investigation, trial and use of CEM VI (C VI) concrete for a sustainable deep foundation future-Paper

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The study investigated a lower-carbon CEM VI-equivalent concrete for deep foundations, combining Portland cement, ground granulated blast-furnace slag (GGBS) and ground limestone. The mix replaced a portion of GGBS with limestone, reducing reliance on a constrained by-product resource. Its embodied carbon was 199 kgCO₂e/m³—below the typical CEM IIIA reference (228 kgCO₂e/m³), though above the CEM IIIB comparison mix (187 kgCO₂e/m³).<br /><br />Laboratory testing found satisfactory fresh-concrete stability, minimal bleeding, adequate workability and strength exceeding the 40 MPa design requirement. Workability retention initially needed improvement; adjusting admixtures extended it beyond five hours for the CFA trial and to seven hours for marine-pile construction. Durability results were broadly comparable with conventional mixes, but chloride resistance was weaker than typical CEM IIIB performance and should be assessed for exposure conditions.<br /><br />A full-scale CFA pile trial confirmed successful pumping and reinforcement-cage installation. The mix was subsequently used to construct two permanent marine piles, placing 200 m³ of concrete. Sixteen 28-day strength tests averaged 54.9 MPa.<br /><br />The authors conclude that CEM VI concrete can be successfully used in deep foundations, while emphasizing the need to optimize admixtures, assess durability requirements and tailor mix designs to project conditions. The results also provide a basis for further reducing cement content and developing mixes under the updated 2023 British Standard.

Keywords

lower-carbon concrete

CEM VI-equivalent

deep foundations

ground granulated blast-furnace slag

ground limestone

embodied carbon

marine piles

CFA pile trial

workability retention

chloride resistance