Influence of Magnesium Oxide on Carbonation of Cement Paste Containing Limestone and Metakaolin

One of the major durability concerns for limestone calcined clay cement (LC3) concrete is its high susceptibility to atmospheric carbonation that could lead an early onset electrochemical corrosion reinforcing steel in structures. Aimed at designing innovative LC3 formulations with potentially enhanced resistance, this preliminary study investigates influence reactive magnesia (MgO) on early-age strength development, hydrates assemblage, and resistance ternary ordinary Portland cement-metakaolin-limestone blends a constant 45% (OPC) replacement level. The results show MgO addition impedes formation AFm phases (hemicarbonate monocarbonate), likely through interfering reactions between metakaolin portlandite. formed brucite due hydration can uptake CO2 some extent, but considerably slower rate, comparison other including AFm, AFt, enhancement pastes insignificant by less than 5%.