Low pH compositions for hardening concrete
A composition for hardening concrete that has a pH of less than 10, and may have a pH of 8 or less. Thus, the hardening composition may be free of or substantially free of alkaline materials. The hardening composition is water-based and includes silica particles and an aluminum-based (e.g., alumina, etc.) stabilizer, which may be present on portions of the surfaces of the silica particles. In use, the hardening composition is applied to the surface of concrete, either alone, with curing compounds, or as part of a polishing process. Any residue that remains on the treated surface may simply be swept, blown, or sprayed away.
1. A composition for a hardening concrete, consisting of:
colloidal silica;
a stabilizer selected from the group consisting of aluminum and alumina;
surfactant; and
water,
the composition having a pH of less than 10 and formulated not to form a hard reside on a surface of the concrete.
2. The composition of claim 1 , having a pH of 8 or less.
3. The composition of claim 1 , having a neutral pH.
4. The composition of claim 1 , having a pH of about 3.5 or less.
5. The composition of claim 1 , wherein silica particles of the colloidal silica have diameters of about 3 nm to about 50 nm.
6. The composition of claim 5 , wherein the silica particles have diameters of about 12 nm.
7. The composition of claim 1 , wherein silica particles of the colloidal silica comprise about 1.5% to about 6% of a weight of the composition.
8. The composition of claim 7 , wherein the silica particles comprise about 4.5% of the weight of the composition.
9. A composition for application to a surface of concrete, comprising:
colloidal silica including silica particles with sizes that enable the silica particles to penetrate into the surface of the concrete to react with calcium hydroxide beneath the surface of the concrete; and
a stabilizer selected from the group consisting of aluminum and alumina, the stabilizer enabling silica particles of the colloidal silica to remain in solution at a pH below 10,
the composition formulated to harden the surface of the concrete without forming a hard residue on the surface.
10. The composition of claim 9 , wherein silica particles of the colloidal silica have diameters of about 3 nm to about 50 nm.
11. The composition of claim 10 , wherein the silica particles have diameters of about 12 nm.
12. The composition of claim 9 , wherein silica particles of the colloidal silica comprise about 1.5% to about 6% of a weight of the composition.
13. The composition of claim 9 , wherein the colloidal silica comprises from about 5% to about 50% of a weight of the composition.
14. The composition of claim 9 , wherein the stabilizer enables the silica particles to remain in solution at a pH of from about 3 to about 7.
15. The composition of claim 9 , wherein the stabilizer enables the silica particles to remain in solution at a pH of about 3.5 or less.
16. A composition for application to a surface of concrete, comprising:
colloidal silica including silica particles with sizes that enable the silica particles to penetrate into the surface of the concrete to react with calcium hydroxide beneath the surface of the concrete;
a stabilizer selected from the group consisting of aluminum and alumina, the stabilizer enabling the silica particles to remain in solution at a pH below 10;
surfactant; and
water,
the composition formulated to harden the surface of the concrete without forming a hard residue on the surface.
17. The composition of claim 16 , wherein silica particles of the colloidal silica comprise about 1.5% to about 6% of a weight of the composition.