Potential SCMs for low-carbon concrete in Australia: Cradle-to-gate LCA and cost perspectives

• Life cycle and cost analysis of eight potential SCMs in Australia. • LC2 delivers top environmental and cost performance across both functional units. • LSP and RMP improve rankings under strength-based evaluation. • Superplasticiser has minimal impact on overall environmental outcomes. • SCMs substitution credits enhance sustainability of LC2, RMP, and RGP mixes. Concrete production is a major source of global emissions, and incorporating supplementary cementitious materials (SCMs) offers a pathway to lower carbon construction. This study evaluates the life cycle and cost performance of eight alternative SCMs in Australia: recycled concrete powder (RCP), clay brick powder (CBP), recycled glass powder (RGP), lithium slag powder (LSP), red mud powder (RMP), limestone calcined clay (LC2), steel slag powder (SSP) and pond ash (PA). The study considers 83 mixes containing these SCMs, as reported in the literature, which achieved 30–40 MPa. The results showed that LC2 achieved the lowest GWP (283 kg CO₂-eq/m³; 8.22 kg CO₂-eq/MPa) and the lowest cost (∼133 AU$/m³). RGP and LSP also reduced ADPF to 71–70 MJ/MPa, while RMP and LSP achieved the lowest strength-normalised costs (3.8–3.9 AU$/MPa). CBP and PA performed worse due to poor reactivity and higher costs (>4.3 AU$/MPa). These findings highlight the potential of LC2, RGP, LSP, and RMP to support circular, low-carbon concrete in Australia.