On the influence of mix design and pre-conditioning on the CO₂- uptake of cementitious materials

¹ c5Lab-Sustainable Construction Materials Association, Edifício Central Park, Rua Central Park 6, 2795-242 Linda-a-Velha, Portugal
² CERENA-Centro de Recursos Naturais e Ambiente, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais 1, 1049- 001, Lisboa, Portugal
³ Department of Buildings, National Laboratory for Civil Engineering, Av. do Brasil 101, 1700-066, Lisbon, Portugal

^* Corresponding author: mattaei@c5lab.pt

Abstract

The cement and concrete sectors are known for their significant contribution to CO₂ emissions. Carbonation curing of concrete precast elements in a CO₂-rich atmosphere is a sustainable approach to reducing the carbon footprint of these industries while simultaneously enhancing the mechanical properties of cement-based materials. This study systematically investigates the influence of mix design and pre- conditioning on CO₂ uptake efficiency and the mechanical performance of mortars. The findings highlight that both factors play a crucial role in optimizing carbonation efficiency. Notably, the study demonstrates that maximizing CO₂ sequestration of 3 wt.% of the mortar can be achieved through controlled pre-curing while mechanical properties are preserved or even improved. This study confirms that carbonation curing can be seamlessly integrated into the precast concrete manufacturing process without requiring additional processing steps. This breakthrough paves the way for practical implementation in industrial settings, offering the dual benefit of carbon reduction and material performance enhancement.