A comparison of the carbon consumption of Continuous flight auger, Auger displacement (CHD) and Precast Driven displacement piles in cohesive ground conditions.-Paper

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The paper compares the embodied carbon of three piling methods—continuous flight auger (CFA), auger displacement (CHD), and driven precast concrete (PCC)—in cohesive ground at two UK sites. Using the EFFC/DFI carbon calculator, the authors assess emissions per pile length, per unit of supported load, and in terms of estimated societal costs from carbon emissions.<br /><br />For a fixed pile length, PCC piles have the lowest reported embodied carbon, reflecting their material quantities and concrete mixes. However, this comparison does not account for differences in load-bearing performance or the pile length required to meet design requirements. When emissions are normalised by supported load, CHD performs best at both sites: reported values are 0.07–0.09 kg CO₂e/kN, compared with 0.16–0.20 for CFA and PCC. The authors attribute this advantage to CHD’s greater bearing efficiency, which can reduce the required pile length and material use. CFA also produces surface spoil, whereas CHD displaces soil laterally and generates substantially less spoil.<br /><br />The societal-cost comparison follows the same pattern: CHD has the lowest estimated impact, while CFA has the highest. The authors argue that carbon assessments should therefore consider not only materials but also installation method and geotechnical performance. They recommend this broader approach when choosing between feasible foundation options.<br /><br />The study concludes that CHD is the most carbon-efficient method in the cases examined. Its findings are based on two sites and specific designs and ground conditions; the authors note that piling methods are not interchangeable for every load or geological setting.

Keywords

embodied carbon

piling methods

continuous flight auger

auger displacement

driven precast concrete

cohesive ground

carbon calculator

supported load

societal cost

geotechnical performance