Abstract: A method in the manufacture of steam-cured light-weight aerated concrete having hydrophobic properties, comprising preparing an aqueous expandable and solidifiable slurry, one or more hydraulic binders and one or more silica-containing materials casting the slurry in a mould; expanding and solidifying, and optionally cutting the solidified slurry; and steam-curing the resultant light-weight aerated concrete, wherein prior to casting said slurry it is admixed with silicone oil in a quantity of 0.05-0.50%, calculated on the dry weight of the starting mixture.