Effect of fly ash on hydration and carbonation of carbonation-cured Portland cements
Geta Bekalu Belayneh, Naru Kim, Joonho Seo, Hansun Kim, Seunghee Park, Seunghee Park, H.M. Son, Solmoi Park, Solmoi Park
Abstract
This study investigates the impact of fly ash on hydration and carbonation processes in carbonation-cured fly ash cements. Cement paste samples with fly ash replacement levels of 0 %, 5 %, 10 % and 30 % underwent carbonation curing for 28 days. Results reveal that the CaO content does not affect the final CO 2 absorption capacity. Instead, optimal fly ash replacement of 10 % enhances CO 2 uptake, yielding 52.9 g of CaCO 3 on the surface after 28 days of curing, compared to 43.4, 43.1 and 48.4 g for 0 %, 5 % and 30 % replaced samples, respectively. Additionally, fly ash incorporation significantly enhances belite reaction and improved CO 2 binding capacity. However, the reaction extent of alite was lower when exposed to CO 2 -curing conditions. These findings advance understanding of blended cements in carbonation-curing, facilitating the development of environmentally friendly and durable concrete structures. • The role of fly ash in hydration of carbonation-cured fly ash cements was studied. • The CaO content of the binder does not significantly affect CO 2 absorption capacity. • The ideal fly ash amount improves CO 2 absorption, with higher amounts leading to faster uptake. • Fly ash incorporation speeds up belite reaction during carbonation curing, enhancing the CO 2 binding capacity of blended PC. • CO 2 -curing reduces alite reaction extent, with higher fly ash replacement ratios correlated with lower alite content.