This specification covers silica fume for use in concrete and other systems containing hydraulic cement. The material shall composed of silica fume, mostly of amorphous silica. Test methods for chemical analysis, moisture content and loss on ignition, bulk density, specific surface, air entrainment of mortar, strength acitivity index, reactivity with cement alkalis, and sulfate resistance of silica fume shall conform to this specification. Physical tests shall include determining the specimen's density and the specific surface by utilizing the BET, nitrogen adsorption method. Silica fume shall be stored in such a manner as to permit easy access for the proper inspection and identification of each shipment.