Composite wall panel with low thermal conductivity and sufficient strength for structural use

Patent metadata

Field	Value
Publication number	US-9249053-B2
Application number	US-201313769808-A
Country	US
Kind code	B2
Filing date	Feb 18, 2013
Priority date	Feb 21, 2012
Publication date	Feb 2, 2016
Grant date	Feb 2, 2016

Abstract

The present invention provides a composite wall panel with good thermal insulation and sufficient strength for structural use which is designed for the fabrication of energy efficient building. The composite wall panel of the present invention comprises a foamed concrete core with sufficient compressive strength and low thermal conductivity which is sandwiched between two lightweight ductile fiber reinforced cementitious composite (FRCC) protective layers with low thermal conductivity, good barrier resistance to moisture/chloride ion/gas, multiple cracking as well as certain amount of steel reinforcements. These composite wall panels are useful in a variety of buildings in both cold and hot regions.

First claim

What is claimed is:

1. A composite for forming a lightweight ductile fiber reinforced cementitious composite (FRCC) protective layer to protect a foamed concrete core in a composite wall panel from heat, moisture, liquid, chemical ions, carbon dioxide and other environmental factors, said composite comprising cement, silica sand, water, polyvinyl alcohol (PVA) fiber, a lightweight filler, pozzolans, superplasticizer, and Hydroxypropyl Methyl Cellulose (HPMC);
wherein said PVA fiber has a mean diameter of about 10 μm to 60 μm and a mean length of about 4 mm to 30 mm;
wherein the lightweight filler comprises bubbles, each of the bubbles having a mean diameter of about 10 μm to 150 μm and a mean density of about 0.15 g/cm 3 to 0.75 g/cm 3 for decreasing thermal conductivity of the FRCC;
wherein the pozzolans comprise fly ash, slag, and silica fume;
wherein a binder comprises the pozzolans and the cement;
wherein a ratio of the water to the cement plus the pozzolans is 0.3-0.45 by weight simultaneously with the bubbles are used as the lightweight filler for improving barrier resistance of the FRCC to liquid, gas and ion;
wherein a ratio of the cement: the fly ash: the water: the silica sand: the lightweight filler: the HPMC: the superplasticizer by weight is 0.2: 0.8: 0.35: 0.165: 0.05: 0.0011: 0.0007;
wherein said composite is lightweight and has a density of about 1200 to 1800 kg/m 3 after curing in wet condition;
wherein said composite has a water permeability of about 0.05×10 −12 to 50×10 −12 m/s;
wherein said composite has a chloride diffusion coefficient of about 0.05×10 −12 to 50×10 −12 m 2 /s;
wherein said composite has a carbonation rate of about 1-2.5 mm/year 0.5 .

2. The composite of claim 1 , wherein said cement is hydraulically settable cement.

3. The composite of claim 1 , wherein the content of said PVA fiber is about 1.5 to 2.5 percent by volume.

4. The composite of claim 1 , wherein each of the silica sand has a mean diameter of about 50 μm to 300 μm.

5. The composite of claim 1 , wherein the bubbles have walls made of glass, ceramic or polymer.

6. The composite of claim 1 , wherein said composite exhibits strain hardening behavior and has a tensile strain capacity of about 0.3% to 4.5%.

7. A FRCC protective layer formed from the composite of claim 1 , wherein at least two FRCC protective layers are precast or cast on site to sandwich said foamed concrete core in order to form a 3-layer concrete structure of the foamed concrete.

8. The FRCC protective layer of claim 7 , wherein each of said FRCC protective layers has a thickness ranging from 5 mm to 50 mm.

9. A foamed concrete structure comprising the FRCC protective layer of claim 1 .

10. The structure of claim 9 , wherein said structure is built by precast or cast on site.

11. A wall panel comprising a foamed concrete core and at least two of a fiber reinforced cementitious composite (FRCC) protective layers;
wherein said foamed concrete core is sandwiched between said at least two FRCC protective layers;
wherein said at least two FRCC protective layers are formed by the composite of claim 1 .

12. The wall panel of claim 11 , wherein said wall panel is made by precast or cast on site.

13. The wall panel of claim 11 , wherein said foamed concrete core has a thickness of about 50 mm to 500 mm.

14. The wall panel of claim 11 , wherein each of said at least two protective layers has a thickness of about 5 mm to 50 mm.

15. The wall panel of claim 11 , wherein said wall panel has a thickness of about 60 mm to 600 mm.

16. The wall panel of claim 11 , wherein said foamed concrete core is formed by a foamed concrete core composition, said composition comprising:
1 to 60 percent by volume of cement;
0 to 75 percent by volume of fly ash;
0 to 50 percent by volume of slag;
0 to 20 percent by volume of silica fume;
0 to 50 percent by volume of sand;
0 to 75 percent by volume of hollow aggregate with water;
0 to 2 percent by volume of naphthalene sulfonate based superplasticizer or polycarboxylic acid based superplasticizer;
1 to 40 percent by volume of foam bubbles, wherein the foam bubbles are formed by combining pressurized air of 1-5 bars and pressurized water of 1-5 bars with a protein based foaming agent or a synthetic based foaming agent in a foaming machine, and the foam bubbles produce air spaces distributed throughout the foamed concrete core; and
0 to 5 percent by volume of one fiber selected from polypropylene fiber, polyethylene fiber, polyvinyl alcohol fiber, glass fiber, or carbon fiber.

Assignees

• Nano & Advanced Materials Inst Ltd

Inventors

• Leung Christopher Kin Ying
• Cheung Kwok Fai
• Zhu Honggang
• Lin Sze Wai

Classifications

• C04B2201/50

  for the mechanical strength · CPC title

• B32B7/02

  Physical, chemical or physicochemical properties · CPC title

• B32B2307/7246

  Water vapor barrier · CPC title

• C04B2201/32

  for the thermal conductivity, e.g. K-factors · CPC title

• C04B14/24

  porous, e.g. foamed glass · CPC title