Mechanical properties and rapid chloride permeability of carbonated concrete containing reactive MgO

Concrete containing reactive MgO can obtain superior mechanical properties to conventional concrete when subjected to accelerated carbonation curing. This study aims to evaluate the influence of r-MgO replacement levels and accelerated carbonation (CO2 concentration of 99%) curing on the mechanical properties and rapid chloride permeability of concrete containing reactive MgO. Concrete cylinders with r-MgO replacement levels of 10%, 30%, 50% 70% and 90% were studied. Experimental results reveal that carbonation curing improves the mechanical properties of reactive MgO concrete compared to uncarbonated specimens, especially during the first three days of carbonation exposure. Influence of accelerated carbonation on concrete specimens with different r-MgO replacement levels, yields the formation of carbonation products, which diminishes the pore volume and affects the rapid chloride permeability. The rapid chloride permeability of concrete is influenced by the decreases in the overall porosity, the conductivity of pore solution and the connectivity of pore structure due to carbonation.