Cement mixes containing additives for altering the hardening rate of chemically bonded silico-phosphate cements and methods therefor

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).

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).

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).