Water absorption of carbonated reactive MgO concrete and its correlation with the pore structure

Water absorption of concrete is an important indicator of concrete durability, which is closely related to the porosity and pore structure of concrete. This study investigates the water absorption behavior of carbonated concrete specimens containing reactive MgO of 10%, 30%, 50%, 70% and 90%. Meanwhile, the corresponding chemical composition and pore structure of each mix was characterized by XRD, TG/DTA, MIP and SEM. Experimental results reveal that the uniform pore structure of carbonated concrete containing 10%, 50%, 70% and 90% reactive MgO result in either high initial sorptivities or high quantities of absorbed water. The gradually microstructural change of a denser outer layer and less-dense inner layer from the surface to the center of the 50% reactive MgO concrete yields a low initial sorptivity and absorbed water quantity, which may have beneficial improvement on the freeze/thaw resistance and de-icing salt scaling resistance of concrete.