Effect of Carbonation on Durability of Hardened Cement Paste in Marine Environments

Abstract

　In this study, the effect of carbonation on the durability of hardened cement paste under marine environment was investigated. Non–carbonated and carbonated samples were immersed in seawater for 91 days. The non–carbonated samples reacted with seawater and cement hydrates to form ettringite, which can cause cracks in the hardened body, and magnesium silicate hydrate (M–S–H), which can weaken the structure. On the other hand, carbonation dissolved calcium aluminate hydrate, Ca(OH)₂, and C–S–H, and neither ettringite nor M–S–H was formed after immersion in seawater in the carbonated samples consisting mainly of CaCO₃, alumina gel, and silica gel.