Effects of carbonation pressure and duration on strength evolution of concrete subjected to accelerated carbonation curing

Accelerated carbonation curing (ACC) is a new technique for curing of concrete that entails sequestering carbon dioxide (CO2) gas into freshly cast concrete, resulting in the improvement of physico-mechanical properties and durability characteristics of concrete. This paper presents the results of an experimental study conducted to evaluate the effects of carbonation pressure and duration on the CO2 uptake and evolution of strength of a concrete mixture. Concrete specimens were cured under six ACC pressures varying from 10 to 60 psi, applied for a duration of 1-10 h in a closed chamber. The effectiveness of varying ACC pressure and duration on the properties of concrete was assessed by measuring compressive strength gain, CO2 uptake, morphology and mineralogy of concrete. It was noted that ACC at 60 psi (414 kPa) for 10 h resulted in the maximum strength gain and CO2 uptake, leading to a post-ACC compressive strength of more than 200% of the pre-ACC strength, and a CO2 uptake of about 11% by mass of cement. Finally, the analysis of variance of the experimental data indicated that the duration of ACC controls the concrete properties more than the pressure used for ACC.