ENGINEERED SELF HEALING CEMENTITIOUS COMPOSITES

• US 20080261027A1
• Filed: 04/17/2008
• Published: 10/23/2008
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Li, Victor C., Yang, En-Hua
• Granted Patent: US 7,572,501 B2
• Time in Patent Office: Days
• US Class Current: 428/332
• CPC Class Codes: C04B 16/0625 Polyalkenes, e.g. polyethylene
• CPC Class Codes: C04B 16/0633 Polypropylene
• CPC Class Codes: C04B 16/0641 Polyvinylalcohols; Polyvinylacetates
• CPC Class Codes: C04B 16/0691 Polyamides; Polyaramides
• CPC Class Codes: C04B 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 18/146 Silica fume
• CPC Class Codes: C04B 2103/44 Thickening, gelling or viscosity increasing agents
• CPC Class Codes: C04B 2111/343 Crack resistant materials
• CPC Class Codes: C04B 2201/52 High compression strength concretes, i.e. with a compression strength higher than about 55 N/mm2, e.g. reactive powder concrete [RPC]
• CPC Class Codes: C04B 24/2623 Polyvinylalcohols; Polyvinylacetates
• CPC Class Codes: C04B 24/383 Cellulose or derivatives thereof
• CPC Class Codes: C04B 28/04 Portland cements
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete
• CPC Class Codes: Y10T 428/249932 Fiber embedded in a layer derived from a water-settable material [e.g., cement, gypsum, etc.]
• CPC Class Codes: Y10T 428/26 Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
• CPC Class Codes: Y10T 428/31725 Of polyamide
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers
• CPC Class Codes: Y10T 428/31938 Polymer of monoethylenically unsaturated hydrocarbon

Abstract

Cementitious composites engineered for self-healing, combining self-controlled tight crack width and extreme tensile ductility. Self-healing takes place automatically at cracked locations without external intervention. In the exemplary embodiment, fiber-reinforced cementitious composites with self-controlled tight crack width less than 50 μm and tensile ductility more than 2% are prepared. Self-healing in terms of mechanical and transport properties recovery of pre-damaged (by pre-cracking) composite is revealed in a variety of environmental exposures, include wetting and drying cycles, water permeation, and chloride submersion.

Claims

1. A self-healing fiber-reinforced cementitious composite comprising:

a binder having a cementitious matrix comprising at least hydraulic cement and water; and

a plurality of discontinuous short fibers having a volume fraction from about 1% to about 4%, said plurality of discontinuous short fibers being generally uniformly-distributed within said cementitious matrix,

wherein said composite having a persistent self-controlled crack width below 150 μ

m, said composite exhibiting strain-hardening behavior under tension with at least 1% strain capacity, said composite having compressive strength in excess of 20 MPa, and crack in the said composite can self-seal in a variety of environmental conditions.

2. The composite of claim 1 wherein said plurality of discontinuous short fibers is selected from a group consisting of aramid, polyvinyl alcohol, high modulus polyethylene, and high tenacity polypropylene.

3. The composite of claim 1 wherein said plurality of discontinuous short fibers have an average diameter of 10 to 100 micrometer and an average length of 4 to 30 mm.

4. The composite of claim 1 wherein said binder is Portland cement.

5. The composite of claim 1 wherein the weight ratio of water to binder is in the range of 0.2 to 0.6.

6. The composite of claim 1, further comprising:

fine aggregates at a weight ratio to said binder up to 2.0.

7. The composite of claim 1, further comprising:

a viscosity agent at a weight ratio to said binder up to 0.01.

8. The composite of claim 7 wherein said viscosity agent is selected from a group consisting of methylcellulose, polyvinyl alcohol, starch and mixture thereof.

9. The composite of claim 1, further comprising:

a water reducing agent at a weight ratio to said binder up to 0.05.

10. The composite of claim 1, further comprising:

at least one of fly ash and silica fume.

11. The composite of claim 1 wherein said composite has a persistent self-controlled crack width below 50 μ

m.

12. A self-healing fiber-reinforced cementitious composite comprising:

a cementitious matrix having at least hydraulic cement and water; and

a plurality of discontinuous short fibers having a volume fraction from about 1% to about 4%, said plurality of discontinuous short fibers being generally uniformly-distributed within said cementitious matrix,

wherein said composite having a persistent self-controlled crack width below 150 μ

m, said composite exhibiting strain-hardening behavior under tension with at least 1% strain capacity, and said composite having compressive strength in excess of 20 MPa.

13. The composite of claim 12 wherein said plurality of discontinuous short fibers is selected from a group consisting of aramid, polyvinyl alcohol, high modulus polyethylene, and high tenacity polypropylene.

14. The composite of claim 12 wherein said plurality of discontinuous short fibers have an average diameter of 10 to 100 micrometer and an average length of 4 to 30 mm.

15. The composite of claim 12, further comprising:

fine aggregates at a weight ratio to said cementitious matrix up to 2.0.

16. The composite of claim 12, further comprising:

a viscosity agent at a weight ratio to said cementitious matrix up to 0.01.

17. The composite of claim 16 wherein said viscosity agent is selected from a group consisting of methylcellulose, polyvinyl alcohol, starch and mixture thereof.

18. The composite of claim 12, further comprising:

a water reducing agent at a weight ratio to said cementitious matrix up to 0.05.

19. The composite of claim 12, further comprising:

at least one of fly ash and silica fume.

20. The composite of claim 12 wherein said composite has a persistent self-controlled crack width below 50 μ

m.