초록 ▼

A cement mix for preparation of a magnesium silico-phosphate cement (MSPC) with an altered hardening rate is provided. The cement mix comprises on the order of 1% of an MF6n− salt or acid. Upon addition of water, the mix produces a final set cement that has similar physical properties to those of a

A cement mix for preparation of a magnesium silico-phosphate cement (MSPC) with an altered hardening rate is provided. The cement mix comprises on the order of 1% of an MF6n− salt or acid. Upon addition of water, the mix produces a final set cement that has similar physical properties to those of a cement prepared from a mix lacking the additive, but with a significantly altered setting time. In some embodiments of the invention, the additive is provided in the form of a coating for the MgO component of the mix. In preferred embodiments, H2TiF6, Na2TiF6 and/or K2TiF6 are used as retarders, while K3AlF6 is used as an accelerant. Other embodiments use M′nMF6 compounds wherein M′ is an alkali metal, an alkaline earth metal, or H, and M is chosen from inter alia Ti (n=2), Zr (n=2), P (n=1), Al (n=3), and Sb (n=1).

대표청구항 ▼

1. A dry cement mix for preparation of a magnesium silico-phosphate cement, the dry cement mix comprising: MgO;a phosphate salt or acid selected from the group consisting of (a) a phosphate salt or acid of the general formula MxHyPO4 (1≦x≦3, y=3−x), where M is selected from the group consisting of H

1. A dry cement mix for preparation of a magnesium silico-phosphate cement, the dry cement mix comprising: MgO;a phosphate salt or acid selected from the group consisting of (a) a phosphate salt or acid of the general formula MxHyPO4 (1≦x≦3, y=3−x), where M is selected from the group consisting of H, Li, Na, K, Rb, Cs, NH4, and any combination of the above; (b) any other phosphate salt or acid that will provide a binder product characterized by the empirical chemical formula MMgPO4.6H2O, and (c) any combination of the above;an aggregate phase selected from the group containing (a) CaSiO3, (b) SiO2, (c) fly ash, (d) sea sand, and (e) any combination thereof; and,a fluorine-containing additive;wherein the fluorine-containing additive is selected from the group consisting of (a) alkali metal salts of [M′F6]n−, (b) alkaline earth metal salts of [M′F6]n−, and (c) HnM′F6, wherein n represents a positive integer and M′ is selected from the group consisting of (a) Ti (n=2), (b) P (n=1), (c) Zr (n=2), (d) Sb (n=1), and (e) Al (n=3). 2. The dry cement mix according to claim 1, wherein the aggregate phase additionally comprises talc. 3. The dry cement mix according to claim 1, wherein the MgO is provided in the form of particles, and the particles of MgO are at least partially coated with the fluorine-containing additive. 4. The dry cement mix according to claim 3, wherein the particle size of the particles of MgO is between 0.1 μm and 100 μm. 5. The dry cement mix according to claim 3, wherein the additive is coated upon the particles of MgO in a thickness of at least 0.5 monolayer. 6. The dry cement mix according to claim 3, wherein the additive is coated upon the particles of MgO in a thickness of at least one monolayer. 7. The dry cement mix according to claim 3, wherein the MgO particles coated with additive are the products of a process of spray drying. 8. The dry cement mix according to claim 3, wherein the MgO particles coated with additive are the products of a process comprising steps of preparing a slurry by adding the additive to water; adding the particles of the MgO to the slurry; feeding the addition product to a spray dryer; and spray-drying the addition product, thereby producing coated particles of MgO. 9. The dry cement mix according to claim 1, wherein M′ is selected from the group consisting of (a) Ti (n=2), (b) P (n=1), (c) Zr (n=2), and (d) Sb (n=1), and further wherein the additive acts as a retarder. 10. The dry cement mix according to claim 9, wherein the retarder is present in an amount of between about 0.05% and about 5% by weight. 11. The dry cement mix according to claim 1, wherein M′ is selected from the group consisting of (a) Al (n=3) and (b) P (n=1), and further wherein the additive acts as an accelerant. 12. The dry cement mix according to claim 11, wherein the accelerant is present in an amount of between about 0.05% and about 5% by weight. 13. A method for producing a dry cement mix according to claim 3, wherein the method comprises: preparing a slurry comprising a fluorine-containing additive in water;adding MgO to the slurry;feeding the product of the step of adding into a dryer;drying the product, thereby producing particles of MgO at least partially coated with the additive; and,mixing the at least partially coated particles of MgO with the phosphate salt or acid and aggregate. 14. The method according to claim 13, wherein the step of drying is selected from the group consisting of spray drying, freeze drying, and drum drying. 15. The method according to claim 13, wherein the step of feeding the product of the step of adding into a dryer comprises a step of feeding the product into a spray dryer. 16. The method according to claim 15, additionally comprising a step of operating the spray dryer under conditions effective to produce droplets of sizes between 0.1 μm and 200 μm. 17. The method according to claim 15, additionally comprising a step of operating the spray dryer under conditions effective to produce particles of sizes between 0.1 μm and 100 μm. 18. The method according to claim 15, wherein the step of spray drying additionally comprises a step of maintaining the temperature of the air exiting the spray dryer above 100° C. 19. The method according to claim 15, wherein the step of spray drying additionally comprises a step of maintaining the temperature of the air exiting the spray dryer at about 105° C. 20. The method according to claim 13, wherein the fluorine-containing additive is selected from the group consisting of H2TiF6, Na2TiF6, K2TiF6, and any combination of the above. 21. The method according to claim 13, wherein the weight ratio between MgO and additive is between 0.2% and 25%. 22. A magnesium silico-phosphate cement (MSPC) comprising: a dry cement mix according to claim 2; and,sufficient water to effect hydraulic hardening of the cement. 23. The MSPC according to claim 22, wherein the crystal structure of the binder product is isomorphic with NH4MgPO4.6H2O. 24. An MSPC comprising: a dry cement mix according to claim 3; and,sufficient water to effect hydraulic hardening of the cement. 25. The MSPC according to claim 24, wherein the crystal structure of the binder product is isomorphic with NH4MgPO4.6H2O. 26. A magnesium silico-phosphate cement (MSPC) having a Vicat penetration force as defined by ASTM standard C 403/C 403M-06 of at least 100 lbf, the MSPC comprising: a dry cement mix comprising:MgO;a phosphate salt or acid selected from the group consisting of (a) a phosphate salt or acid of the general formula MxHyPO4 (1≦x≦3, y=3−x) where M is selected from the group consisting of H, Li, Na, K, Rb, Cs, NH4, and any combination of the above; (b) any other phosphate salt or acid that will provide a binder product characterized by the empirical chemical formula MMgPO4.6H2O; and (c) any combination of the above;an aggregate phase selected from the group containing (a) CaSiO3, (b) SiO2, (c) fly ash, (d) sea sand, and (e) any combination thereof; and,sufficient water to effect hydraulic hardening of the cement, the water containing a fluorine-containing additive, in a form selected from the group consisting of (i) suspension, (ii) solution, (iii) any combination thereof;wherein the fluorine-containing additive is selected from the group consisting of (a) alkali metal salts of [M′F6]n−, (b) alkaline earth metal salts of [M′F6]n−, and (c) HnM′F6, wherein n represents a positive integer and M′ is selected from the group consisting of (a) Ti (n=2), (b) P (n=1), (c) Zr (n=2), (d) Sb (n=1), and (e) Al (n=3). 27. The MSPC according to claim 26, wherein the aggregate phase additionally comprises talc. 28. The MSPC according to claim 26, wherein the crystal structure of the binder product is isomorphic with NH4MgPO4.6H2O. 29. The MSPC according to claim 26, wherein M′ is selected from the group consisting of (a) Ti (n=2), (b) P (n=1), (c) Zr (n=2), and (d) Sb (n=1), and further wherein the additive acts as a retarder. 30. The MSPC according to claim 29, wherein the retarder is present in an amount of between about 0.05% and about 5% by weight based upon the weight of dry cement. 31. The MSPC according to claim 30, wherein M′ is selected from the group consisting of (a) Al (n=3) and (b) P (n=1), and further wherein the additive acts as an accelerant. 32. The MSPC according to claim 31, wherein the accelerant is present in an amount of between about 0.05% and about 5% by weight based upon the weight of dry cement. 33. A method for altering the rate of hardening of a magnesium silicophosphate cement (MSPC), comprising: obtaining a magnesium silico-phosphate cement mix comprising:MgO;a phosphate salt or acid selected from the group consisting of (a) a phosphate salt or acid of the general formula MxHyPO4 (1≦x≦3, y=3−x) where M is selected from the group consisting of H, Li, Na, K, Rb, Cs, NH4, and any combination of the above; (b) any other phosphate salt or acid that will provide a binder product characterized by the empirical chemical formula MMgPO4.6H2O; and (c) any combination of the above; and,an aggregate phase selected from the group containing (a) CaSiO3, (b) SiO2, (c) fly ash, (d) sea sand, (e) talc, and (f) any combination thereof;adding to the cement mix a fluorine-containing additive that alters the rate of hardening of an MSPC; and,adding sufficient water to the mixture to effect hydraulic setting of the cement;wherein the fluorine-containing additive is selected from the group consisting of (a) alkali metal salts of [M′F6]n−, (b) alkaline earth metal salts of [M′F6]n−, and (c) HnM′F6, wherein n represents a positive integer and M′ is selected from the group consisting of (a) Ti (n=2), (b) P (n=1), (c) Zr (n=2), (d) Sb (n=1), and (e) Al (n=3). 34. The method according to claim 33, wherein the binder product is isomorphic with NH4MgPO4.6H2O. 35. The method according to claim 33, wherein M′ is selected from the group consisting of (a) Ti (n=2), (b) Zr (n=2), (c) P (n=1), and (d) Sb (n=1), and further wherein the additive acts as a retarder. 36. The method according to claim 35, wherein the retarder is selected from the group consisting of (a) Na2TiF6; (b) K2TiF6; and (c) any combination of the above. 37. The method according to claim 35, wherein the retarder is present in an amount of between about 0.05% and about 5% by weight based upon the weight of dry cement. 38. The method according to claim 35, wherein M′ is selected from the group consisting of (a) Al (n=3) and (b) P (n=1), and further wherein the additive acts as an accelerant. 39. The method according to claim 38, wherein the accelerant is present in an amount of between about 0.05% and about 5% by weight based upon the weight of dry cement. 40. The method according to claim 33, additionally comprising: providing the MgO in the form of particles; and,coating the particles of MgO at least partially with the fluorine-containing additive. 41. A method for altering the rate of hardening of an MSPC having a Vicat penetration force as defined by ASTM standard C 403/C 403M-06 of at least 100 lbf, comprising: obtaining a magnesium silico-phosphate cement mix comprising:MgO;a phosphate salt or acid selected from the group consisting of (a) a phosphate salt or acid of the general formula MxHyPO4 (1≦x≦3, y=3−x) where M is selected from the group consisting of H, Li, Na, K, Rb, Cs, NH4, and any combination of the above; (b) any other phosphate salt or acid that will provide a binder product characterized by the empirical chemical formula MMgPO4.6H2O; and (c) any combination of the above; and,an aggregate phase selected from the group containing CaSiO3, SiO2, fly ash, sea sand, talc, and any combination thereof;preparing a combination of a fluorine-containing additive and volume of water sufficient to effect hydraulic setting of the cement, the combination in a form selected from the group consisting of (a) a suspension of the fluorine-containing additive in the water, (b) a solution of the fluorine-containing additive in the water, and (c) any combination of the above; and,admixing the cement mix and the combination;wherein the fluorine-containing additive is selected from the group consisting of (a) alkali metal salts of [M′F6]n−, (b) alkaline earth metal salts of [M′F6]n−, and (c) HnM′F6, wherein n represents a positive integer and M′ is selected from the group consisting of (a) Ti (n=2), (b) P (n=1), (c) Zr (n=2), (d) Sb (n=1), and (e) Al (n=3). 42. The method according to claim 41, wherein the binder product is isomorphic with NH4MgPO4.6H2O. 43. The method according to claim 41, wherein M′ is selected from the group consisting of (a) Ti (n=2), (b) Zr (n=2), (c) P (n=1), and (d) Sb (n=1), and further wherein the additive acts as a retarder. 44. The method according to claim 43, wherein the retarder is selected from the group consisting of (a) Na2TiF6; (b) K2TiF6; and (c) any combination of the above. 45. The method according to claim 43, wherein the retarder is present in an amount of between about 0.05% and about 5% by weight based upon the weight of dry cement. 46. The method according to claim 43, wherein M′ is selected from the group consisting of (a) Al (n=3) and (b) P (n=1), and further wherein the additive acts as an accelerant. 47. The method according to claim 43, wherein the accelerant is present in an amount of between about 0.05% and about 5% by weight based upon the weight of dry cement.