Freeze-thaw durability of dry cast cementitious mixtures

• US 7,922,808 B2
• Filed: 06/14/2005
• Issued: 04/12/2011
• Est. Priority Date: 06/15/2004
• Status: Active Grant

• Current Assignee: Construction Research & Technology GmbH (BASF SE)
• Original Assignee: Construction Research & Technology GmbH (BASF SE)
• Inventors: Christensen, Bruce J., Miller, Patrick, Brower, Lynn E., Vickers, Thomas M. Jr.
• Primary Examiner(s): Lorengo; Jerry
• Assistant Examiner(s): ABU ALI, SHUANGYI
• Application Number:
  US11/152,957
• Publication Number:
  US 20050274294A1
• Time in Patent Office: 2,128 Days
• Field of Search: 106/713, 106/802
• US Class Current: 106/713
• CPC Class Codes: C04B 14/022 Carbon
• CPC Class Codes: C04B 16/08 porous, e.g. expanded polystyrene beads or microballoons
• CPC Class Codes: C04B 16/085 expanded in situ, i.e. during or after mixing the mortar, concrete or artificial stone ingredients
• CPC Class Codes: C04B 20/008 Micro- or nanosized fillers, e.g. micronised fillers with particle size smaller than that of the hydraulic binder colloidal silica C04B14/062 ; silica fume C04B18/146
• CPC Class Codes: C04B 2103/20 Retarders
• CPC Class Codes: C04B 2103/302 Water reducers
• CPC Class Codes: C04B 2103/304 Air-entrainers
• CPC Class Codes: C04B 2103/408 Dispersants
• CPC Class Codes: C04B 2103/65 Water proofers or repellants
• CPC Class Codes: C04B 2103/67 Biocides
• CPC Class Codes: C04B 2103/69 Fungicides
• CPC Class Codes: C04B 2111/29 Frost-thaw resistance
• CPC Class Codes: C04B 22/0013 Boron compounds
• CPC Class Codes: C04B 22/068 Peroxides, e.g. hydrogen peroxide
• CPC Class Codes: C04B 22/10 containing carbon in the anion
• CPC Class Codes: C04B 24/123 Amino-carboxylic acids
• CPC Class Codes: C04B 24/129 Compounds containing one or more nitrogen-to-nitrogen double bonds, e.g. azo-compounds
• CPC Class Codes: C04B 24/18 Lignin sulfonic acid or derivatives thereof, e.g. sulfite lye
• CPC Class Codes: C04B 24/223 Sulfonated melamine-formaldehyde condensation products
• CPC Class Codes: C04B 24/226 Sulfonated naphtalene-formaldehyde condensation products
• CPC Class Codes: C04B 24/2647 : containing polyether side chains
• CPC Class Codes: C04B 28/02 : containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 38/02 : by adding chemical blowing agents
• CPC Class Codes: Y02W 30/91 : Use of waste materials as fillers for mortars or concrete

Abstract

An improved freeze-thaw durability dry cast cementitious composition is provided that uses very small (0.1 μm to 100 μm average diameter) polymeric microspheres that are blended directly into the mixture and optionally gas-generating additives. The polymeric microspheres provide void spaces in the material matrix that act to increase freeze-thaw durability of the material. In this dry cast cementitious composition, polymeric microspheres act as pre-formed voids.

Claims

1. A cementitious freeze-thaw damage resistant dry cast composition comprising hydraulic cement, polymeric microspheres, and optionally gas generating additives.

2. The cementitious dry cast composition of claim 1 wherein the water to cement ratio is from about 0.2 to about 0.8.

3. The cementitious dry cast composition of claim 1 wherein the polymeric microspheres comprise a polymer that is at least one of polyethylene, polypropylene, polymethyl methacrylate, poly-o-chlorostyrene, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polymethacrylonitrile, polystyrene, or copolymers or mixtures thereof.

4. The cementitious dry cast composition of claim 1 wherein the polymeric microspheres comprise at least one copolymer of vinylidene chloride-acrylonitrile, polyvinylidene chloride-copolyacrylonitrile, vinyl chloride-vinylidene chloride or mixtures thereof.

5. The cementitious dry cast composition of claim 1 wherein the polymeric microspheres are present in a range from about 1% to about 4% by weight of dry cement.

6. The cementitious dry cast composition of claim 1 wherein the polymeric microspheres are present in a range from about 0.05% to about 4% by volume percent of the cementitious mixture.

7. The cementitious dry cast composition of claim 1 wherein the polymeric microspheres are at least one of gas filled or liquid filled.

8. The cementitious dry cast composition of claim 1 wherein the polymeric microspheres have an average diameter of about 0.1 μ

m about 100 μ

m.

9. The cementitious dry cast composition of claim 1 wherein the polymeric microspheres have an average diameter of about 10 μ

m or less.

10. The cementitious dry cast composition of claim 1 wherein the cementitious composition contains gas generating additives.

11. The cementitious dry cast composition of claim 1 wherein the gas generating additive is at least one of hydrazide, hydrazine, azide, or azo compound.

12. The cementitious dry cast composition of claim 1 wherein the gas generating additive is at least one of azodicarbonamide, sodium bicarbonate, organic peroxide, inorganic peroxide, toluenesulfonylhydrazide, benzenesulfonyl hydrazide, toluenesulfonyl acetone hydrazone, toluenesulfonylsemicarbazide, phenyltetrazole, sodium borohydride, activated carbon or dinitroso-pentamethylenetetramine.

13. The cementitious dry cast composition of claim 1 wherein the gas generating additive is present in a range from about 0.05 to 2 weight percent by dry weight of cement.

14. The cementitious dry cast composition of claim 1 further comprising at least one of air entrainers, aggregates, pozzolans, dispersants, set and strength accelerators/enhancers, set retarders, water reducers, wetting agents, water soluble polymers, rheology modifying agents, water repellents, dampproofing admixtures, permeability reducers, pumping aids, fungicidal admixtures, germicidal admixtures, insecticide admixtures, finely divided mineral admixtures, alkali-reactivity reducer, bonding admixtures, shrinkage reducing admixtures or mixtures thereof.

15. The cementitious dry cast composition of claim 14 wherein the dispersant is at least one of calcium lignosulfonates, sulfonated melamine formaldehyde condensates, polyaspartates, sodium naphthalene sulfate formaldehyde condensate resins, oligomers, or polycarboxylates.

16. A dry cast cementitious article comprising the composition of claim 1.

17. A method for preparing a freeze-thaw damage resistant dry cast cementitious article comprising:

a. mixing hydraulic cement, polymeric microspheres and optionally a gas generating additive to produce a cementitious composition mixture; and

b. forming the mixture into an article.

18. The method of claim 17, wherein the polymeric microspheres or gas generating additives are added in at least one of the following forms:

a. compact mass;

b. powder;

or

c. liquid admixture.

19. The method of claim 17 wherein the mixture contains a gas generating additive.

20. The method of claim 17 wherein the polymeric microspheres are at least one of gas filled or liquid filled.