Effect of Carbonation on the Microstructure and Phase Development of High-Slag Binders

Abstract The drive for sustainable concrete production favors the use of high replacement levels supplementary cementitious materials (SCMs) in mix. SCMs such as fly ash and slag, however, although they improve sustainability well most durability properties, increases carbonation rate. Carbonation decreases pH pore solution, making steel reinforcement susceptible to corrosion. effect is, not confined change solution. We investigated changes microstructure phases high-slag binders due carbonation. resistance mortars with 50 70% slag were at exposure conditions 2%CO 2 , 50%RH, 23 °C. carbonated non-carbonated parts subjected various characterization techniques investigate on phase development. Results confirmed absence portlandite all regions (“colorless” by phenolphthalein test, which indicated that color solution was buffer pH). Significant reduction amount C-S-H, increase calcium carbonate, been observed regions. Aragonite, a polymorph CaCO 3 very prominent mortars.