Effect of Strength and Carbonation Sand Cement Brick Containing Fly Ash under CO2 Curing

Carbonation offers a helpful approach to store CO2 inside the cement-based product, which is reduces greenhouse gas emissions and the consequent decrease in global temperature. This study aimed to assess the effects of CO2 curing on the physical and mechanical properties of cement sand brick made using combination fly ash (FA) and Portland cement as cement binary systems. Cement sand brick underwent air curing and accelerated carbonation. The cement sand brick moulds size of 215 mm length x 103 mm width x 65 mm. FA was used to replace cement with substitution of 0, 20, 25, 30, 35 and 40%. After mould, the cement sand bricks were subjected to a 24 and 48 hours for air curing and high concentration of CO2 curing chamber. Every mixture made using the binary cement mixed that included FA was lower compared to the control sample. However, strength of brick using carbonation-cured was 14% higher than that of air-cured brick. This improvement is ascribed to the increased concentration of calcium carbonate, a carbonation-related byproduct, in the pore matrix brick. It shows that the carbonation cured had a slightly lower water penetration depth compared to sample by air cured specimens. It is anticipated that the carbonation-cured specimens will have a denser surface layer. The surface layer of mortar that resists water penetration becomes less porous because of the carbonation of the mortar, which densifies the microstructure of the mortar. It can be concluded that CO2 curing process is a technologically advanced method of sequestering CO2 that insignificantly give a negative impact to the strength and durability of cement sand brick.