Patent ID: 8366821

Claim:
A magnesium silico-phosphate cement (MSPC) comprising: a. a dry cement mix to which a fluorine-containing additive has been added, comprising: i. MgO; ii. a phosphate salt or acid selected from the group consisting of (a) a phosphate salt or acid of the general formula M x H y PO 4 (1≦x≦3, y=3−x), where M is selected from the group consisting of H, Li, Na, K, Rb, Cs, NH 4 , 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 MMgPO 4 ·6H 2 O, and (c) any combination of the above; iii. an aggregate phase selected from the group containing (a) CaSiO 3 , (b) SiO 2 , (c) fly ash, (d) sea sand, and (e) any combination thereof; and, iv. a fluorine-containing additive; and, b. sufficient water to effect hydraulic hardening of said cement; wherein said fluorine-containing additive is selected from the group consisting of (a) alkali metal salts of [M′F 6 ] n− , (b) alkaline earth metal salts of [M′F 6 ] n− , and (c) H n M′F 6 , 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).