Thermally adaptive ductile concrete

• US 9,512,344 B2
• Filed: 02/14/2014
• Issued: 12/06/2016
• Est. Priority Date: 02/15/2013
• 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: Desai, Devki, Li, Victor C.
• Primary Examiner(s): Green, Anthony J
• Application Number:
  US14/768,049
• Publication Number:
  US 20150376489A1
• Time in Patent Office: 1,026 Days
• US Class Current: 1/1
• CPC Class Codes: C04B 14/062 Microsilica, e.g. colloïdal silica preparing microsilica slurries or suspensions C04B18/148
• CPC Class Codes: C04B 14/48 Metal
• CPC Class Codes: C04B 16/00 Use of organic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of organic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
• CPC Class Codes: C04B 16/06 fibrous
• 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 18/08 Flue dust , i.e. fly ash
• CPC Class Codes: C04B 20/0048 Fibrous materials
• CPC Class Codes: C04B 20/10 Coating or impregnating roofing granules E04D7/005
• CPC Class Codes: C04B 2103/0071 Phase-change materials, e.g. latent heat storage materials used in concrete compositions
• CPC Class Codes: C04B 2103/32 Superplasticisers
• CPC Class Codes: C04B 2111/00318 Materials characterised by relatively small dimensions, e.g. small thickness
• CPC Class Codes: C04B 2201/32 for the thermal conductivity, e.g. K-factors
• CPC Class Codes: C04B 24/08 Fats; Fatty oils; Ester type waxes; Higher fatty acids, i.e. having at least seven carbon atoms in an unbroken chain bound to a carboxyl group; Oxidised oils or fats
• CPC Class Codes: C04B 24/36 Bituminous materials, e.g. tar, pitch C04B24/243 takes precedence
• CPC Class Codes: C04B 28/04 Portland cements
• CPC Class Codes: C09K 5/14 Solid materials, e.g. powdery or granular
• CPC Class Codes: Y02A 30/30 in transportation, e.g. on roads, waterways or railways
• CPC Class Codes: Y02W 30/91 Use of waste materials as fillers for mortars or concrete

Abstract

A Thermally Adaptive Ductile Concrete (PCM-ECC) having a tensile ductility ceramic with 5 times the thermal resistance, 2 times the specific heat capacity, and 400 times the tensile strain capacity of regular concrete.

Claims

1. A fiber-reinforced cementitious composite comprising:

a binder of cement, class F fly ash, and water;

a plurality of uniformly distributed oil-coated polyvinyl alcohol (PVA) or polyethylene (PE) fibers at 1.5% to 3% of the total volume;

a sand with average diameter of about 100 microns;

a microencapsulated paraffin wax that changes a state of matter at a temperature between 18 and 26 degrees Celsius; and

a water reducing admixture in sufficient quantity to obtain a mini-cone flow rate of a pre-cured fiberless matrix of the fiber-reinforced cementitious composite between 24 and 33 seconds,

wherein said composite having an ultimate tensile strength of at least 4 MPa and exhibiting a compressive strength of about 28 MPa.

2. The fiber-reinforced cementitious composite of claim 1 wherein said microencapsulated paraffin wax is not greater than about 10% of the total mass of the composite.

3. The fiber-reinforced cementitious composite of claim 1 wherein said plurality of fibers have an average diameter of 30-50 microns and an average length of 8-12mm.

4. The fiber-reinforced cementitious composite of claim 1 wherein said binder is a Portland cement.

5. The fiber-reinforced cementitious composite of claim 1 wherein said binder is a Type 1 Portland cement.

6. The fiber-reinforced cementitious composite of claim 1 wherein a weight ratio of water to binder is between 0.2 and 0.4.

7. The fiber-reinforced cementitious composite of claim 1 wherein a weight ratio of water to binder is 0.3.

8. The fiber-reinforced cementitious composite of claim 1 wherein a specific heat capacity is between 1000-2000 J/Kg.K when the composite is at temperatures below 20 or above 25 degrees Celsius and a peak specific heat capacity at 23 degrees Celsius is 20% higher than the specific heat capacity value average.

9. The fiber-reinforced cementitious composite of claim 1 wherein a thermal conductivity of the composite is 20% lower than that of a composite without said microencapsulated paraffin wax.

10. The fiber-reinforced cementitious composite of claim 1 wherein said composite has an average specific heat capacity of 1600 J/Kg.K and a peak specific heat capacity of 1900-2000 J/Kg.K at a phase change temperature of 23°

C.

11. The fiber-reinforced cementitious composite of claim 1 wherein said composite having an average thermal conductivity between 0.30 and 0.50 W/m.K.

12. The fiber-reinforced cementitious composite of claim 1 wherein said composite having an ultimate tensile strength of about 4.3 MPa.

13. The fiber-reinforced cementitious composite of claim 1 wherein said composite exhibiting strain-hardening behavior resulting in a tensile strain capacity of at least 0.5%.

14. The fiber-reinforced cementitious composite of claim 1 wherein said composite exhibiting strain-hardening behavior resulting in a tensile strain capacity between 3% and 5%.

15. The fiber-reinforced cementitious composite of claim 1 wherein said composite exhibiting a density of about 1650 kg/m³.