Life cycle assessment shows admixtures support high-performance low-carbon LC3 concrete

Limestone calcined clay cements (LC 3 ) have high potential to reduce concrete’s carbon footprint. However, the impact of admixtures on carbon footprint of LC 3 concrete via performance enhancement is not well understood. This paper investigates the carbon footprint, compressive strength performance, and carbonation resistance of CEM II/A-LL, LC 3 -50, and LC 3 -35 concretes dosed with admixtures (polycarboxylate ether-based superplasticizer, C-S-H nanoparticle accelerator, silane-based water repellent). Generally, the results show that accelerator can increase the strength and carbonation exposure classes of LC 3 concretes. We show that LC 3 -50 and LC 3 -35 concretes reduced CO 2 -eq. emissions by 22 – 38 % compared to CEM II/A-LL, and that admixtures can contribute 13% of their cradle-to-gate CO 2 -eq. emissions. Optimal admixture addition and clinker content depends on the strength and carbonation exposure classes required, but of the concrete types studied, the optimum combinations always contained LC 3 and not CEM II/A-LL. Admixtures support the production of high-performance concretes with low carbon footprint.