Cementitious materials and method of making the same

The cementitious material comprises an initial mixture of portland cement clinker and a modifier ranging in weight from approximately 0.5% to 5%, preferably 1%, of the weight of the clinker. The modifier is selected from a group comprising (a) a melamine formaldehyde-sodium bisulfite copolymer, and (b) sodium naphthalene sulfonate. The portland cement clinker and the modifier are intimately mixed and caused to react together in a solid state reaction by energetically grinding them together in a highly energetic ball-and-tube grinding mill to a high degree of fineness of at least approximately 5000 Blaine. Modified cementitious materials are produced by providing an additional constituent in the initial mixture comprising a hard, dense, substantially inert mineral material ranging up to 70% of the mixture by weight. The percentages of the portland cement clinker and the modifier are correspondingly reduced. The modified initial mixture is ground as before. The cementitious materials are substituted for traditional portland cement in making concrete having increased strength, density, durability and impermeability, while having decreased water demand, porosity and capillarity. The mineral material is selected from a group comprising sand, comminuted stone, comminuted scrap material from glass making, comminuted waste material from ore enrichment plants, comminuted volcanic material, comminuted slag, fly ash, comminuted pumice, and comminuted perlites.