Study on the early volume stability of cement-based materials during CO2 curing

In this study, the impact of carbonation curing regime and fly ash dosage on the volume stability of concrete was investigated. The shrinkage of cement pastes specimens incorporating 0-30 % fly ash after 2-24 h pre-conditioning and 4-24 h carbonation curing was experimentally determined. Carbonation curing can lead to a maximum increase of 39.4 % on dry shrinkage of cement paste compared to the standard-cured ones. Prolonged carbonation curing can also enlarge the average and critical pore sizes by 123.4 % and 697.8 %, respectively. The water penetration of prolonged carbonation-cured cement mortar was increased by 56.1 %, consequently. However, appropriate carbonation curing increased compressive strength and sequestered CO2 2 effectively. The addition of an appropriate dosage of low-calcium fly ash can mitigate the adverse impact of carbonation curing on the volume stability of cement paste.