Method for making carbonated precast concrete products with enhanced durability

A method of making a carbonated precast concrete product, comprising:

• obtaining an intermediate having a core and an external layer disposed on a surface of the core, the core having a first composition and the external layer having a second composition different than the first composition, the intermediate being demolded, wherein faces of the intermediate are exposed to ambient air, and wherein a binder of the second composition of the external layer is selected from the group consisting of ground granulated blast-furnace slag (GGBFS), steel slag, and stainless steel slags;
• conditioning the intermediate to obtain a conditioned intermediate thereby reducing a water-to-binder ratio of at least the external layer, including reducing the water-to-binder ratio by evaporating a portion of water contained in the external layer;
• after the conditioning of the intermediate, at least partially compensating for an excessive reduction of the water-to-binder ratio of the external layer by causing a weight gain in the external layer by applying an aqueous medium on an outer surface of the external layer of the conditioned intermediate to increase the water-to-binder ratio of the external layer to obtain a moisturized intermediate, the excessive reduction of the water-to-binder ratio resulting in a moisture content at the outer surface being about 50% of a moisture content at the core of the conditioned intermediate, the external layer extending from the outer surface of the conditioned intermediate towards the surface of the core;
• and
• curing the moisturized intermediate with carbon dioxide to obtain the carbonated precast concrete product.