A case study and life cycle assessment of CO₂ dosed ready mixed concrete for ground contact under near shore exposure

The utilization of carbon dioxide in concrete has emerged as a promising strategy for simultaneously reducing cement related greenhouse gas emissions and improving concrete performance. However, most published studies have been conducted under laboratory conditions, while evaluations integrating industrial scale concrete production remain limited. This study presents an industrial case study of CO₂ dosed ready mixed concrete produced under routine commercial manufacturing conditions using an international CO₂ injection system for construction applications in Saudi Arabia. A conventional ordinary Portland cement (OPC) mixture, together with three industrially produced concrete mixtures, namely OPC with CO₂ dosing, fly ash concrete, and fly ash concrete with CO₂ dosing, were experimentally evaluated under an actual near shore field curing environment along the Arabian Gulf. Fresh, mechanical, durability, and environmental properties were assessed through an integrated experimental program and a cradle to gate life cycle assessment normalized by compressive strength. The results demonstrate that fly ash incorporation produced the greatest reduction in global warming potential. Whereas CO₂ dosing provided additional, although comparatively smaller, environmental benefits because of the relatively low CO₂ dosage (up to 0.70 kg/m³) relative to the embodied greenhouse gas emissions associated with the cement incorporated in the concrete mixtures. The integrated assessment demonstrates that the environmental performance of CO₂ dosed concrete is governed primarily by cement reduction rather than direct CO₂ mineralization. The findings of this study further highlight that carbon capture is not environmentally free; the captured CO₂ may be treated as a credit, but the associated capture, compression, transportation, and injection processes introduce additional environmental burdens that should be considered within a transparent system level assessment. Consequently, under the investigated industrial production conditions, cement reduction through supplementary cementitious materials (i.e., fly ash in this case) remained the primary driver of greenhouse gas emission reduction. Although this study represents a specific industrial case study of CO₂ dosed concrete for ground contact applications, the obtained insights suggest that integrating experimentally measured engineering performance with a transparent environmental assessment is essential when evaluating CO₂ utilization technologies.