Concrete mixtures having aqueous foam admixtures

• US 20070056481A1
• Filed: 12/19/2005
• Published: 03/15/2007
• Est. Priority Date: 09/09/2005
• Status: Active Grant

• Current Assignee: Charles D. Welker
• Original Assignee: Jack B. Parson Companies
• Inventors: Gray, Lonnie
• Granted Patent: US 7,670,426 B2
• Time in Patent Office: Days
• US Class Current: 106/819
• CPC Class Codes: C04B 14/048 Granite
• CPC Class Codes: C04B 14/06 Quartz; Sand
• CPC Class Codes: C04B 14/22 Glass ; Devitrified glass
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 2103/10 Accelerators; Activators
• CPC Class Codes: C04B 2103/302 Water reducers
• CPC Class Codes: C04B 2103/32 Superplasticisers
• CPC Class Codes: C04B 2103/40 Surface-active agents, dispersants
• CPC Class Codes: C04B 22/085 containing nitrogen in the anion, e.g. nitrites
• CPC Class Codes: C04B 2201/50 for the mechanical strength
• CPC Class Codes: C04B 24/003 Phosphorus-containing compounds
• CPC Class Codes: C04B 24/005 Halogen-containing compounds
• CPC Class Codes: C04B 24/02 Alcohols; Phenols; Ethers
• CPC Class Codes: C04B 24/38 Polysaccharides or derivatives thereof C04B24/243 takes precedence
• CPC Class Codes: C04B 24/383 Cellulose or derivatives thereof
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 38/10 by using foaming agents C04B38/02 takes precedenceor by using mechanical means, e.g. adding preformed foam
• CPC Class Codes: C04B 40/0633 Chemical separation of ingredients, e.g. slowly soluble activator
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete

Abstract

Flowable concrete mixtures have an aqueous foam admixture mixed therein to give the concrete mixture desired strength, flowability, and density. The concrete mixtures include a hydration stabilizer to stabilize the aqueous foam. The hydration stabilizer inhibits the reaction between the hydraulic cement and the water in the aqueous foam. The aqueous foam can be further stabilized using a fluorochemical surfactant. Preferred fluorochemical surfactants comprise an oligomer having at least one hydrophilic nonionic monomer and at least one hydrophilic anionic monomer.

Claims

1. A concrete mixture, comprising:

(i) a hydraulic cement;

(ii) a hydration stabilizer that inhibits hydration of the hydraulic cement;

(iii) water;

(iv) a foam comprising water, a foaming agent, and a surfactant, wherein the foam is stabilized in the presence of the hydraulic cement by the hydration stabilizer.

2. A concrete mixture as in claim 1, wherein the hydration stabilizer is a calcium binding agent.

3. A concrete mixture as in claim 2, wherein the hydration stabilizer is a derivative of a phosphonic acid.

4. A concrete mixture as in claim 1, wherein the hydration stabilizer is selected from the group consisting of N-nitrilo tris(methylene phosphonic acid), 1,2-ethanediyl bis[nitrilo di(methylene phosphonic acid)];

1,6-hexanediyl bis[nitrilo di(methylene phosphonic acid)], amino tris(methylene phosphonic acid), polymethoxy polyphosphonic acids, and combinations thereof.

5. A concrete mixture as in claim 1, wherein the hydration stabilizer further comprises an accelerator.

6. A concrete mixture as in claim 1, wherein the surfactant comprises a fluorochemical surfactant.

7. A concrete mixture as in claim 6, wherein the fluorochemical surfactant comprises an oligomer comprising a hydrophilic nonionic monomer.

8. A concrete mixture as in claim 6, wherein the fluorochemical surfactant comprises a hydrophilic anionic monomer.

9. A concrete mixture as in claim 6, wherein the fluorochemical surfactant has the formula:

R_f-E_a-(S)_b-[M₁]_x-[M₂]_y-H

wherein

R_f is (i) a straight chain, branched chain, or cyclic perfluoroalkyl of 1 to about 20 carbon atoms, (ii) a perfluoroalkyl substituted with a perfluoroalkoxy of 2 to about 20 carbon atoms, (iii) a perfluoroalkyl oligomer or polymer of greater than 10 carbon atoms, or (iv) a combination thereof;

E_a is (i) a direct bond;

(ii) a branched, straight chain, or cyclic alkylene of 2 to about 20 carbon atoms;

(iii) the alkylene of (ii) interrupted by one or more groups selected from the group consisting of —

NR—

, —

O—

, —

S—

, —

SO₂—

, —

COO—

, —

OOC—

, —

CONR—

, —

NRCO—

, —

SO₂NR—

, —

NRSO₂—

, —

SiR₂—

;

or (iv) the alkylene of (ii) terminated at the R_f end with —

CONR—

or —

SO₂NR—

;

R is independently hydrogen, an alkyl of 1-10 carbon atoms, or a hydroxyalkyl of 2 to 10 carbon atoms;

a and b are independently 0 or 1;

-[M₁]- represents a non-ionic hydrophilic monomer unit;

-[M₂]- represents an anionic hydrophilic monomer unit; and

x and y represent the number of monomer units present in the co-oligomers and are both greater than 0;

the sum of x and y being between 5 and 200, and y/(x+y) being between 0.01 and 0.98.

10. A concrete mixture as in claim 9, wherein:

-[M₁]- is selected from the group consisting of acrylamide, methacrylamide, diacetone acrylamide, 2-hydroxyethyl methacrylate, derivatives of acrylic, methacrylic, maleic, fumaric and itaconic acids, amides, and vinyl esters containing from 1 to about 20 carbon atoms in the ester group, and combinations thereof; and

-[M₂]- is selected from the group consisting of acrylic and methacrylic acids and salts thereof, maleic, fumaric and itaconic acids and salts thereof, acrylamidopropane sulfonic acid and salts thereof, and mono-olefinic sulfonic and phosphonic acids and salts thereof, and combinations thereof.

11. A concrete mixture as in claim 6, wherein the foam comprises at least about 5% by volume of the concrete mixture.

12. A concrete mixture as in claim 6, wherein the foam comprises at least about 10% by volume of the concrete mixture.

13. A concrete mixture as in claim 1, wherein the hydration stabilizer is included in an amount sufficient to inhibit the reaction between the hydraulic cement and the water in the foam for greater than about 30 minutes.

14. A concrete mixture as in claim 1, wherein the hydration stabilizer is included in an amount sufficient to inhibit the reaction between the hydraulic cement and the water in the foam for greater than about 1 hour.

15. A cured concrete manufactured by pouring the concrete mixture of claim 1 and allowing the concrete mixture to cure.

16. A concrete mixture as in claim 1 that achieves a compressive strength of greater than 2500 psi in 28 days, when allowed to set.

17. A concrete mixture as in claim 1 that achieves a compressive strength of greater than 3000 psi in 28 days, when allowed to set.

18. A concrete mixture as in claim 1 that achieves a compressive strength of greater than 4000 psi in 28 days, when allowed to set.

19. A concrete mixture, comprising:

(i) a hydraulic cement;

(ii) a hydration stabilizer that inhibits hydration of the hydraulic cement;

(iii) water;

(iv) a dispersant;

(v) aggregate; and

(vi) a foam comprising water, a foaming agent, and a fluorochemical surfactant, wherein the foam comprises a plurality of air bubbles that are stabilized by the fluorochemical surfactant, the fluorochemical surfactant comprising an oligomer having at least one hydrophilic nonionic monomer or at least one hydrophilic anionic monomer.

20. A concrete mixture as in claim 19, wherein the hydration stabilizer is a derivative of a phosphoric acid.

21. A concrete mixture as in claim 19, wherein

the foam comprises one or more fatty acid alcohols selected from the group consisting of straight and branched chain fatty acid alcohols of about 8 to about 16 carbon atoms;

the foam comprises an anionic polysaccharide selected from the group consisting of rhamsan gums, xanthan gums, guar gums, and locust bean gums; and

the foaming agent comprises a non-fluorinated anionic surfactant having from about 8 to about 18 carbon atoms.

22. A concrete mixture as in claim 19, wherein the composition and initial set time make the concrete mixture suitable for use in ready-mix applications.

23. A concrete mixture as in claim 19, wherein the composition and initial set time make the concrete mixture suitable for use in precast applications.

24. A concrete mixture as in claim 19, wherein:

-[M₁]- is selected from the group consisting of acrylamide, methacrylamide, diacetone acrylamide, 2-hydroxyethyl methacrylate, derivatives of acrylic, methacrylic, maleic, fumaric and itaconic acids, amides, and vinyl esters containing from 1 to about 20 carbon atoms in the ester group, and combinations thereof; and

-[M₂]- is selected from the group consisting of acrylic and methacrylic acids and salts thereof, maleic, fumaric and itaconic acids and salts thereof, acrylamidopropane sulfonic acid and salts thereof, and mono-olefinic sulfonic and phosphonic acids and salts thereof, and combinations thereof.

25. A concrete composition as in claim 19, wherein the aggregate comprises less than 40% fine aggregate.

26. A concrete composition as in claim 19, wherein the aggregate comprises less than 40% coarse aggregate.

27. A concrete mixture as in claim 19 that achieves a compressive strength of greater than 3000 psi in 56 days, when allowed to set.

28. A method for stabilizing a foam in a concrete mixture, comprising:

(i) providing an aqueous foam admixture comprising a plurality of air bubbles;

(ii) providing a cementitious mixture comprising hydraulic cement, water, and aggregate; and

(iii) mixing together the cementitious mixture, the aqueous foam admixture and a hydration stabilizer, wherein the hydration stabilizer inhibits the destruction of the air bubbles by the hydraulic cement.

29. A concrete mixture as in claim 28, wherein the hydration stabilizer is a calcium binding agent.

30. A concrete mixture as in claim 29, wherein the hydration stabilizer is a derivative of a phosphonic acid.

31. A concrete mixture as in claim 30, wherein the hydration stabilizer is selected from the group consisting of N-nitrilo tris(methylene phosphonic acid), 1,2-ethanediyl bis[nitrilo di(methylene phosphonic acid)];

1,6-hexanediyl bis[nitrilo di(methylene phosphonic acid)], amino tris(methylene phosphonic acid), polymethoxy polyphosphonic acids, and combinations thereof

32. A method as in claim 28, wherein the hydration stabilizer is mixed with the hydraulic cement before the water is mixed with the hydraulic cement.

33. A method as in claim 28, wherein the hydration stabilizer is mixed with the water before the water is mixed with the hydraulic cement.

34. A method as in claim 28, wherein the hydration stabilizer is mixed with the cement after the cement is mixed with the foam.

35. A method as in claim 28, wherein the hydration stabilizer is mixed with the cement before the cement is mixed with the foam.

36. A method as in claim 28, wherein providing the foam admixture compnses:

(i) providing a foaming concentrate comprising a foaming agent; and

(ii) mixing the foaming concentrate with water and air under shear forces sufficient to form the plurality of air bubbles.

37. A concrete mixture as in claim 36, wherein

the foaming concentrate comprises one or more fatty acid alcohols selected from the group consisting of straight and branched chain fatty acid alcohols of about 8 to about 16 carbon atoms;

the foaming concentrate comprises an anionic polysaccharide selected from the group consisting of rhamsan gums, xanthan gums, guar gums, and locust bean gums; and

the foaming agent comprises a non-fluorinated anionic surfactant having from about 8 to about 18 carbon atoms.

38. A method as in claim 28, wherein the foam admixture fuirther comprises a foam stabilizing fluorochemical surfactant.

39. A method as in claim 38, wherein the fluorochemical surfactant comprises an oligomer comprising a hydrophilic nonionic monomer or a hydrophilic anionic monomer.

40. A method as in claim 38, wherein the fluorochemical surfactant has the formula:

R_f-E_a-(S)_b-[M₁]_x-[M₂]_y-H

wherein

R_f is (i) a straight chain, branched chain, or cyclic perfluoroalkyl of 1 to about 20 carbon atoms, (ii) a perfluoroalkyl substituted with a perfluoroalkoxy of 2 to about 20 carbon atoms, (iii) a perfluoroalkyl oligomer or polymer of greater than 10 carbon atoms, or (iv) a combination thereof;

E_a is (i) a direct bond, (ii) a branched, straight chain, or cyclic alkylene of 2 to about 20 carbon atoms, (iii) the alkylene of (ii) interrupted by one or more groups selected from the group consisting of —

NR—

, —

O—

, —

S—

, —

SO₂—

, —

COO—

, —

OOC—

, —

CONR—

, —

NRCO—

, —

SO₂NR—

, —

NRSO₂—

, —

SiR₂—

;

or (iv) the alkylene of (ii) terminated at the R_f end with —

CONR—

or —

SO₂NR—

;

R is independently hydrogen, an alkyl of 1-10 carbon atoms, or a hydroxyalkyl of 2 to 10 carbon atoms;

a and b are independently 0 or 1;

-[M₁]- represents a non-ionic hydrophilic monomer unit;

-[M₂]- represents an anionic hydrophilic monomer unit; and

x and y represent the number of monomer units present in the co-oligomers and are both greater than 0;

the sum of x and y being between 5 and 200, and y/(x+y) being between 0.01 and 0.98.

41. A cured concrete composition manufacture according to the method of claim 28.

42. A cured concrete as in claim 41 wherein the concrete achieves a compressive strength of greater than 3000 psi in 28 days.