Influence of durability properties on life-cycle carbon reduction of low-carbon mortar with similar compressive strength

The imperative for carbon reduction in the construction industry is gaining momentum. A pivotal strategy in this endeavor is the adoption of low-carbon cementitious materials and the enhancement of concrete structures' service life. The chloride-induced corrosion and water ingress in reinforced concrete is a pervasive issue, often resulting in premature structural failure and substantial economic loss. This study focuses on four low-carbon cementitious materials: calcium sulphoaluminate cement (CSA), CO 2 cured calcium sulphoaluminate cement (CSA-C), alkali-activated slag (AAS), and limestone calcined clay cement (LC 3 ). Different types of low-carbon mortars with similar compressive strength were used for mercury intrusion porosimetry, hydration phase analysis, chloride ion diffusion, and water permeability tests. The results reveal that AAS and LC 3 possess superior or similar chloride diffusion and water permeation resistance compared with Portland cement (PC) mortar. Life cycle assessment (LCA) and carbon emission analyses show that AAS and LC 3 produce markedly lower carbon emissions during production compared to PC. The expected repair time from the chloride ion diffusivity and water permeability suggests that LC 3 and AAS have extended repair time and reduced annual carbon emissions, underscoring their viability as PC alternatives. It is highlighted that the annual carbonation emissions taking concrete durability into consideration is a more appropriate index for assessing the environmental performance of low-carbon cementitious materials, rather than the total carbon emissions. • Durability of four low-carbon concrete under same strength was investigated. • CO 2 curing enhances pore structure and strength of CSA mortar. • LC 3 mortar has much lower chloride diffusivity and moderate water permeability. • AAS has the lowest total carbon emission from concrete production. • LC 3 and AAS have lower annual carbon emissions than PC.