초록 ▼

Novel hydraulic cements are disclosed that include reactive magnesium oxide prepared by low temperature calcination. The cements can be formulated to suit a large number of applications with various setting times, strength and levels of sustainability either by adding iron salts such as ferrous sulf

Novel hydraulic cements are disclosed that include reactive magnesium oxide prepared by low temperature calcination. The cements can be formulated to suit a large number of applications with various setting times, strength and levels of sustainability either by adding iron salts such as ferrous sulfate or blending with other compatible faster setting hydraulic cements such as Portland cement or by using both methods. The compositions are able to incorporate relatively large amounts of low cost pozzolans such as fly ash to advantage as well as wastes. Many excellent properties are exhibited and in particular good comprehensive strength and resistance to sulfates is able to be achieved.

대표청구항 ▼

The invention claimed is: 1. A hydraulic cement composition consisting essentially of: a hydraulic cement component; a magnesium oxide component; and a pozzolan component, wherein the magnesium oxide component consists essentially of reactive magnesium oxide hydratable to brucite and prepared by lo

The invention claimed is: 1. A hydraulic cement composition consisting essentially of: a hydraulic cement component; a magnesium oxide component; and a pozzolan component, wherein the magnesium oxide component consists essentially of reactive magnesium oxide hydratable to brucite and prepared by low temperature calcination at a temperature of less than 750�� C. from materials excluding dolomite, and substantially ground to a particle size with greater than 95% of the particles less than 120 μm in size, the magnesium oxide component making up at least 5% by weight of a combination of the hydraulic cement component and the magnesium oxide component, said composition excluding components which form magnesium oxychlorides and magnesium oxysulfates with the reactive magnesium oxide. 2. The hydraulic cement composition as defined in claim 1, wherein the hydraulic cement component comprises Portland cement. 3. The hydraulic cement composition as defined in claim 1, wherein the hydraulic cement component comprises calcium aluminate cements. 4. The hydraulic cement composition as defined in claim 1, wherein the hydraulic cement component comprises a geopolymer forming cement. 5. The hydraulic cement composition as defined in claim 1, wherein the pozzolan component comprises fly ash. 6. The hydraulic cement composition as defined in claim 1, wherein the pozzolan component comprises ground blast furnace slag. 7. The hydraulic cement composition as defined in claim 1, which is treated by heating or steaming at temperatures in the range 20-1000�� C. 8. The hydraulic cement composition as defined in claim 1, wherein the pozzolan comprises at least one component selected from the group consisting of fly ash, flue wastes, slags including iron ore slag, other wastes from the metal production industry, silica fume, ground brick, and sewerage sludge ash. 9. A hydraulic cement composition consisting essentially of: at least one a hydraulic cement; a magnesium oxide component; and optionally, at least one pozzolan, wherein the magnesium oxide is at a level of at least 5% by weight of a combination of the at least one hydraulic cement and the magnesium oxide and wherein the magnesium oxide consists essentially of reactive magnesium oxide hydratable to brucite prepared by low temperature calcination at a temperature of less than 750�� C. and fine grinding to a particle size with greater than 95% passing 120 μm. 10. A hydraulic cement composition as a defined in claim 9, wherein the hydraulic cement comprises Portland cement. 11. A hydraulic cement composition as defined in claim 9, wherein the composition includes said pozzolan and wherein the pozzolan comprises at least one pozzolan selected from the group consisting of fly ash, flue wastes, slags including iron ore slag, other wastes from the metal production industry, silica fume, ground brick, and sewerage sludge ash. 12. A hydraulic cement composition as defined in claim 9, wherein the hydraulic cement is Portland cement and the composition includes a pozzolan comprising fly ash.