Abstract: A method and composition for preparing concrete elements comprising the steps of mixing a composition comprising the following components expressed in parts by weight (p):a) 100 p of Portland cement;b) 30 p to 100 p or better 40 p to 70 p of fine sand having a grain size of at least 150 micrometers;c) 10 p to 40 p or better 20 p to 30 p of amorphous silicon having a grain size of less than 0.5 micrometers;d) 20 p to 60 p or better 30 p to 50 p of ground quartz having a grain size of less than 10 micrometers;e) 25 p to 100 p, or better 45 p to 80 p of steel wool;f) a dispersing agent;g) 13 p to 26 p or better 15 p to 22 p of water; and after setting, curing the concrete at a temperature of 250.degree. C. or higher, for a length of time sufficient to transform cement hydration products into crystalline hydrates of the xonotlite type; thus eliminating substantially all of the free water and at least the main part of the adsorbed and chemically bonded water.

Abstract: A metal fiber concrete composition for molding a concrete element, the composition being essentially constituted by a Portland cement, granular elements, fine elements for pozzolan reaction, metal fibers, a dispersing agent, optionally other additives, and water. The preponderant granular elements have a maximum grain size D of not more than 800 micrometers. The preponderant metal fibers have individual lengths 1 lying in the range 4 mm to 20 mm. The ratio R of the mean length L of the fibers divided by said maximum size D of the granular elements is not less than 10. The amount of preponderant metal fibers is such that the volume of preponderant metal fibers lies in the range 1.0% to 4% of the volume of the concrete after setting.