Low-Carbon Cement and Low-Cement Concrete: Comparative Decarbonization Potential and the Distribution of Carbon Cost and Risk Across the Value Chain

Decarbonizing cement and concrete production requires multiple simultaneous strategies, since no single technology is sufficient. Two approaches dominate: low-carbon cement with reduced clinker content (supply-side) and low-cement concrete and structures delivering a given service through efficient design (demand-side). Direct comparisons between paths remain rare. Literature shows incompatible baselines, system boundaries, and functional units, and several studies are bounded at the factory gate (i.e., excluding demand-side measures). Despite the limitations, this paper attempts an explicit comparison of technical potential and burdens for stakeholders. Three outcomes emerge: (1) Complementarity: supply-side measures dominate impact but demand-side efficiency remains indispensable for net zero. (2) Asymmetric cost and risk burdens: supply-side costs concentrate in few actors that pass and dilute them downstream, whereas demand-side responsibility disperses across designers, contractors, and owners lacking incentives, contractual mechanisms and liability protection; the apparent lower risk of low-carbon cement is institutional, not technical. (3) Interconnected gaps sustain the imbalance and bound the present analysis: non-harmonised LCA conventions, cost-pass-through evidence limited to one residential case, absent data on willingness-to-pay and carbon-performance liability, and policy instruments targeting material rather than functional level. Demand-side action lags not on technical performance but on lack of means to verify, budget, insure and reward it.