Use of a CO2 curing step to improve the properties of concrete prepared with recycled aggregates

The paper presents the results of an experimental study on properties of concrete prepared with recycled mortar aggregate (RMA) that has been modified by a CO2 curing method. The experimental investigation was conducted in two parts. Firstly, the properties such as density, 10% fine value, and water absorption of CO2 improved RMA were determined. Secondly, the fresh, hardened and durability properties including slump, compressive and tensile splitting strength, drying shrinkage and chloride penetrability of the concretes prepared with RMA and CO2 cured aggregates (CI-RMA) were determined. It was found that the density, and 10% fine value of the CI-RMA was higher, and the water absorption of the CI-RMA was lower when compared to the untreated RMA. For the concrete, not only was there an improvement in the mechanical properties and resistance to chloride ion penetration for the concrete prepared with CI-RMA, but also the drying shrinkage was decreased.