Polymer-cement composites and methods of making same
A polymer-cement composite comprises, by weight percent, about 40% to 50% inert, inorganic filler material, such as silica sand; about 12% to 23% latex, preferably in aqueous suspension; about 20% to 25% hydraulic cement; and reactive silica in an amount of at least about 6 weight percent. The reactive silica is a pozzolanic material, and in preferred embodiments, where the cement is portland cement, comprises an advantageous mixture of precipitated and ground silica. All solid components have a particle size of less than about 300 microns. The polymer-cement composite is preferably made by dry mixing of the powdered components throughly in a high intensity mixer, adding the liquid components, and wet mixing to form a thoroughly blended, de-aired green mixture. The green mixture is formed into any desired shape, cured, and dried. Preferably, the product is cured in a warm, moist environment.
1. A polymer-cement composite comprising:
about 12 to about 23 weight percent latex, the latex including polymer solids and water;
about 20 to about 25 weight percent portland cement, the cement being present in an amount sufficient to provide a weight ratio of water to cement of up to about 0.49 and a ratio of latex polymer solids to cement (ls/c) of between 0.3 and 0.6, calcium hydroxide being produced when the cement is hydrated with water;
filler in an amount sufficient to provide a weight ratio of filler to cement of about 1.90 to about 2.10; and
about 6 to about 15 weight percent reactive silica to react with the calcium hydroxide.
2. The polymer-cement composite of claim 1 wherein the latex comprises an aqueous suspension.
3. The polymer-cement composite of claim 2 wherein the latex comprises an aqueous suspension of styrene-butadiene polymer.
4. The polymer-cement composite of claim 2 wherein the latex comprises an aqueous suspension of styrene-acrylate polymer.
5. The polymer-cement composite of claim 2 wherein the latex comprises an aqueous suspension of polyacrylate polymer solids.
6. The polymer-cement composite of claim 2 wherein the aqueous suspension comprises about 56 to about 58 weight percent polymer solids.
7. The polymer-cement composite of claim 1 wherein the latex comprises redispersible latex.
8. The polymer-cement composite of claim 1 wherein all solid components have particle sizes less than 300 microns.
9. The polymer-cement composite of claim 1 comprising about 40 to about 50 weight percent filler.
10. The polymer-cement composite of claim 1 wherein the filler is selected from the group consisting of silica sand, ground nepheline syenite, ground sandstone, ground limestone, ground dolomite, coarse fly ash having particle sizes from about 50 to about 300 microns and ground basalt and combinations thereof.
11. The polymer-cement composite of claim 1 wherein the filler is a lightweight material selected from the group consisting of fly ash, perlite and vermiculite having particle sizes from about 50 to about 300 microns and combinations thereof.
12. The polymer-cement composite of claim 1 wherein the components are present in the following ratios:
Components
Ratio
1
water/cement
0.43-0.49 by weight
2
water/(cement + reactive silica)
0.30-0.34 by weight
3
latex solids/cement
0.30-0.60 by weight
4
filler/cement
1.90-2.10 by weight
5
reactive silica/cement
0.28-0.61 by weight
6
calcia/total reactive silica
0.80-1.30 by moles.
13. The polymer-cement composite of claim 1 wherein the reactive silica is selected from the group consisting of ground silica, silica fume (microsilica), precipitated silica, fly ash having an average particle size of about 0.01 to about 45 microns and ground blast furnace slag and combinations thereof.
14. The polymer-cement composite of claim 13 wherein the reactive silica has an average particle size range from about 0.01 microns to about 45 microns.
15. The polymer-cement composite of claim 1 wherein the reactive silica comprises a mixture of ground silica and precipitated silica.
16. The polymer-cement composite of claim 15 comprising:
5 to 12 weight percent ground silica; and
1 to 2 weight percent precipitated silica.
17. A polymer-cement composite comprising:
about 12 to about 23 weight percent latex, the latex, including polymer solids and water;
about 20 to about 25 weight percent portland cement, said cement being present in an amount sufficient to provide a weight ratio of water to cement of up to about 0.49 and a ratio of latex polymer solids to cement (ls/c) of between about 0.30 and about 0.60 by weight, calcium hydroxide being produced when the cement is hydrated with water;
filler in an amount sufficient to provide a weight ratio of filler to cement of between about 1.90 to about 2.10; and
about 6 to about 15 weight percent reactive silica to react with the calcium hydroxide, said reactive silica comprising a mixture of ground silica and precipitated silica.
18. The polymer-cement composite of claim 17 wherein the latex comprises an aqueous suspension.
19. The polymer-cement composite of claim 18 comprising 7 to 13 weight percent latex polymer solids.
20. The polymer-cement composite of claim 18 wherein the aqueous suspension comprises about 56 to about 58 weight percent polymer solids.
21. The polymer-cement composite of claim 18 wherein the latex comprises an aqueous suspension of styrene-butadiene polymer.
22. The polymer-cement composite of claim 18 wherein the latex comprises an aqueous suspension of styrene-acrylate polymer.
23. The polymer-cement composite of claim 18 wherein the latex comprises an aqueous suspension of polyacrylate polymer.
24. The polymer-cement composite of claim 17 wherein the latex comprises redispersible latex.
25. The polymer-cement composite of claim 17 wherein all solid components have particle sizes less than 300 microns.
26. The polymer-cement composite of claim 17 wherein the filler is selected from the group consisting of silica sand, ground nepheline syenite, ground sandstone, ground limestone, ground dolomite, coarse fly ash having particle sizes from about 50 to about 300 microns and ground basalt and combinations thereof.
27. The polymer-cement composite of claim 17 wherein the filler is a lightweight material selected from the group consisting of fly ash, perlite and vermiculite having particle sizes from about 50 to about 300 microns and combinations thereof.
28. The polymer-cement composite of claim 17 wherein the reactive silica has an average particle size range from about 0.01 to about 45 microns.
29. The polymer-cement composite of claim 17 comprising:
5 to 12 weight percent ground silica; and
1 to 2 weight percent precipitated silica.
30. The polymer-cement composite of claim 17 wherein the components are present in the following ratios:
Components
Ratio
1
water/cement
0.43-0.49 by weight
2
water/(cement + reactive
0.30-0.34 by weight
silica)
3
latex solids/cement
0.30-0.60 by weight
4
filler/cement
1.90-2.10 by weight
5
reactive silica/cement
0.28-0.61 by weight
6
calcia/total reactive silica
0.80-1.30 by moles.
31. The polymer-cement composite of claim 1 wherein the water is present in an amount sufficient to provide a ratio of water to cement of about 0.43 to about 0.49 by weight.
32. The polymer-cement composite of claim 1 wherein the reactive silica is provided in at least an amount sufficient to react with essentially all of the calcium hydroxide.
33. The polymer-cement composite of claim 17 wherein the water is present in an amount sufficient to provide a ratio of water to cement of about 0.43 to about 0.49 by weight.
34. The polymer-cement composite of claim 17 wherein the reactive silica is provided in at least an amount sufficient to react with essentially all of the calcium hydroxide.
35. A polymer-cement composite comprising:
about 6 to about 13 weight percent latex polymer solids;
about 20 to about 25 weight percent portland cement, said cement being present in an amount sufficient to provide a ratio of latex polymer solids to cement (ls/c) of between 0.3 and 0.6;
water in an amount sufficient to provide a weight ratio of water to cement of up to about 0.49, calcium hydroxide being produced when the cement is hydrated with the water;
about 6 to about 15 weight percent reactive silica to react with the calcium hydroxide; and
filler in an amount sufficient to provide a ratio of filler to cement of about 1.90 to about 2.10 by weight.
36. The polymer-cement composite of claim 35 wherein the latex polymer solids are provided in the form of an aqueous suspension.
37. The polymer-cement composite of claim 36 wherein the aqueous suspension is selected from the group consisting of an aqueous suspension of styrene-butadiene polymer solids, an aqueous suspension of styrene-acrylate polymer solids and an aqueous suspension of polyacrylate polymer solids.
38. The polymer-cement composite of claim 35 wherein the latex polymer solids comprises redispersible latex.
39. The polymer-cement composite of claim 35 wherein the water is present in an amount sufficient to provide a ratio of water to cement of about 0.43 to about 0.49 by weight.
40. The polymer-cement composite of claim 35 wherein the reactive silica is provided in at least an amount sufficient to react with essentially all of the calcium hydroxide produced by the portland cement hydration.
41. The polymer-cement composite of claim 35 wherein the reactive silica is selected from the group consisting of ground silica and precipitated silica and combinations thereof.