A water-based coating is described comprising colloidal silica and lamellar materials such as glass flakes or mica admixed with a water-based film-forming polymeric carrier such as an epoxy. The water-based epoxy coating can be directly applied to unset, set, cured or uncured concrete and exhibits a water vapor permeance of about 0.14 perms by ASTM F-1869-04. A method for using the coating is also disclosed.