Durable medium-density fibre cement composite

• US 20060288909A1
• Filed: 10/07/2003
• Published: 12/28/2006
• Est. Priority Date: 10/07/2002
• Status: Active Grant

• Current Assignee: James Hardie Technology Limited (James Hardie Industries Plc)
• Original Assignee: James Hardie International Finance B.V. (James Hardie Industries Plc)
• Inventors: Zammit, Michael, Luo, Caidian, Merkley, Donald J., Naji, Basil
• Granted Patent: US 7,993,570 B2
• Time in Patent Office: Days
• US Class Current: 106/681
• CPC Class Codes: C04B 14/06 Quartz; Sand
• CPC Class Codes: C04B 18/082 Cenospheres
• CPC Class Codes: C04B 18/146 Silica fume
• CPC Class Codes: C04B 18/24 Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper , cork
• CPC Class Codes: C04B 20/0048 Fibrous materials
• CPC Class Codes: C04B 20/1051 Organo-metallic compounds; Organo-silicon compounds, e.g. bentone
• CPC Class Codes: C04B 20/1066 Oxides, Hydroxides
• CPC Class Codes: C04B 2111/00129 Extrudable mixtures
• CPC Class Codes: C04B 2111/22 Carbonation resistance
• CPC Class Codes: C04B 2111/29 Frost-thaw resistance
• CPC Class Codes: C04B 28/02 containing hydraulic cements other than calcium sulfates
• CPC Class Codes: C04B 38/00 Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof treating slag with gases or gas generating material C04B5/06 ; expanded graphite C04B35/536
• CPC Class Codes: C04B 38/0054 the pores being microsized or nanosized
• CPC Class Codes: C04B 40/0064 Processes of the Magnini or Hatscheck type
• CPC Class Codes: C04B 40/0071 making use of a rise in pressure
• CPC Class Codes: C04B 40/024 Steam hardening, e.g. in an autoclave
• CPC Class Codes: C04B 41/009 characterised by the material treated
• CPC Class Codes: C04B 41/483 Polyacrylates
• CPC Class Codes: C04B 41/4853 Epoxides
• CPC Class Codes: C04B 41/4884 Polyurethanes; Polyisocyanates
• CPC Class Codes: C04B 41/52 : Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
• CPC Class Codes: C04B 41/522 : Multiple coatings, for one of the coatings of which at least one alternative is described
• CPC Class Codes: C04B 41/63 : Macromolecular compounds
• CPC Class Codes: C04B 41/71 : at least one coating being an organic material
• CPC Class Codes: Y02W 30/91 : Use of waste materials as fillers for mortars or concrete

Abstract

A cementitious product and method of modifying the properties of a low or medium density FRC product by providing a predetermined pore size distribution. The pore size distribution is obtained such that in critical zones of the distribution, the pore volume is substantially equivalent to or less than the pore volume in a respective critical zone of a conventional high density FRC product. The resultant material provides improved properties over conventional medium density FRC products, in particular improved freeze/thaw durability and/or improved workability.

Claims

1. A method of modifying the properties of a low or medium density FRC product comprising providing the low or medium density FRC product with a predetermined pore size distribution such that in particular critical zones of said distribution, the pore volume is substantially equivalent to or less than the pore volume in a respective critical zone of a conventional high density FRC product.

2. A method as claimed in claim 1 wherein the predetermined pore size distribution is obtained by chemical modification.

3. A method as claimed in claim 1 wherein the pore size distribution is obtained by including a predetermined quantity of pore modifying components into a cementitious formulation from which the FRC product is obtained.

4. A method as claimed in claim 3 wherein the pore modifying components include lignocellulosic fibres treated with a water repellant agent and microfine siliceous material.

5. A method as claimed in claim 1 wherein the predetermined pore size distribution is obtained by physical modification.

6. A method as claimed in claim 1 wherein during its production the low or medium density FRC product is subjected to a light press to provide the required predetermined pore size distribution.

7. A method as claimed in claim 6 wherein the light press is sufficient to provide the desired predetermined pore size distribution but maintain a density of no greater than 1.6 g/cm³.

8. A method as claimed in claim 7 wherein the pressure applied is sufficient to provide the predetermined pore size distribution but maintain a density of between about 1.1 and 1.55 g/cm³.

9. A method as claimed in claim 1 wherein the critical zones of said pore size distribution are in the region of 1 to 10 microns mean pore diameter size and/or in the region of 10 to 100 microns mean pore diameter size.

10. A method as claimed in claim 9 wherein the pore volume in one or more of the critical zones is no greater than about 150% of the pore volume in the corresponding pore size region of a conventional high density FRC product.

11. A method as claimed in claim 1 wherein the predetermined pore size distribution is obtained by a combination of chemical and physical modifications.

12. A method as claimed in claim 1 a predetermined pore size distribution is obtained to provide improved freeze/thaw durability to the FRC product.

13. A method as claimed in claim 1 wherein a predetermined pore sized distribution is obtained to provide reduced propensity to carbonation or differential carbonation of the FRC product.

14. A method of providing a low or medium density FRC product, comprising the steps of:

i) providing a formulation for a low or medium density product;

ii) forming a green article from said formulation;

iii) curing said green article to form said product;

wherein prior to step iii)

a) one or more pore size modifying agents are added to the formulation and/or

b) the green shaped article is subjected to a light press such that the pore volume of the product is reduced as compared with a conventional product emanating from steps i) to iii), while maintaining a density of no greater than about 1.6 g/cm³.

15. A method as claimed in claim 14 wherein a formulation for a medium density product is prepared, and the formulation density reduced toward a low density formulation such that light pressing brings the product back towards the medium density range of about 1.1 to 1.55 grams per cm³.

16. A method as claimed in claim 14 wherein the predetermined pore size distribution is obtained by chemical modification.

17. A method as claimed in claim 16 wherein the pore size distribution is obtained by including a predetermined quantity of pore modifying components into the cementitious formulation.

18. A method as claimed in claim 17 wherein the pore modifying components include lignocellulosic fibres treated with a water repellant agent and microfine siliceous material.

19. A method as claimed in claim 14 wherein the predetermined pore size distribution is obtained by physical modification of the FRC product.

20. A method as claimed in claim 14 wherein during its production the low or medium density FRC product is subjected to a light press to provide the required predetermined pore size distribution.

21. A method as claimed in claim 20 wherein the light press is sufficient to provide the desired predetermined pore size distribution but maintain a density of no greater than 1.6 g/cm³.

22. A method as claimed in claim 21 wherein the pressure applied is sufficient to produce the predetermined pore size distribution but maintain a density of between about 1.1 and 1.55 g/cm³.

23. A method as claimed in claim 14 wherein the critical zones of said pore size distribution are in the region of 1 to 10 microns mean pore diameter size and/or in the region of 10 to 100 microns mean pore diameter size.

24. A method as claimed in claim 23 wherein the pore volume in one or more of the critical zones is no greater than about 150% of the pore volume in the corresponding pore size region of a conventional high density FRC product.

25. A method as claimed in claim 14 wherein the predetermined pore size distribution is obtained by a combination of chemical and physical modifications.

26. A method as claimed in claim 14 wherein a predetermined pore size distribution is obtained to provide improved freeze/thaw durability to the FRC product.

27. A method as claimed in claim 14 wherein a predetermined pore sized distribution is obtained to provide reduced propensity to carbonation or differential carbonation of the FRC product.

28. A method of modifying the properties of a low or medium density FRC article comprising adjusting the pore size distribution of the article such that over at least one particular pore size range, the total pore volume is no greater than about 150% of the pore volume in a corresponding pore size range of a conventional high density FRC product.

29. A cementitious product comprising a body constructed from fibre reinforced cement and having a density of no more than about 1.6 grams/cm³ wherein the product has a predetermined pore size distribution such that in particular critical zones of said distribution, the pore volume is substantially equivalent to or less than the pore volume in a respective critical zone of a conventional high density FRC product.

30. A cementitious product as claimed in claim 29 having a density of between about 1.1 and 1.55 g/cm³.

31. A cementitious product as claimed in claim 29 wherein the critical zones of said pore size distribution are in the region of 1 to 10 microns mean pore diameter size and/or in the region of 10 to 100 microns mean pore diameter size.

32. A cementitious product as claimed in claim 29 wherein the pore volume in one or more of the critical zones is no greater than 150% of the pore volume and the corresponding pore size region of a conventional high density FRC product.