BUILDING PRODUCT

Abstract

A building product in the form of an internal lining board. The board is made up of a mixture of a food crop byproduct, a binder, a water reducing agent, cellulose, and water. The mixture is provided between two sheets of lining paper.

Claims

1. A building product in the form of an internal lining board, the board being made up of a mixture of the following materials: a food crop byproduct; a binder; a water reducing agent; cellulose; and water, with the mixture being provided between two sheets of lining paper.

2. A building product according to claim 1, wherein the food crop byproduct comprises any of: common wheat, oats, rapeseed, barley straw, giant miscanthus, bamboo, flax, rice straw, corn straw, sugarcane, bagasse, or sisal straw.

3-10. (canceled)

11. A building product according to claim 1, wherein the cementitious product has the following constituents: TABLE-US-00006 (CaO)2 SiO2 40-60% (CaO)3 SiO2  5-8% (CaO)3 AI203 6% ± 2 (CaO)4 AI203 Fe203 9% ± 2 (CaO)12 (AI203)7 3% ± 1 CaCO3 10-15% Ca5 (Si04)2 CO3 10-15% (CaO)4 (AI2O3)3 SO3 3% ± 1 K2 Mg2 (SO4)3 .sup. 1% ± 0.5 CaSO4 2% ± 1 CaO 2% ± 2 MgO 4% ± 1 SiO2 .sup. 1% ± 0.5 (CaO)2 AI2O3 SiO2 1.5% ± 0.5 Other amorphous solids 4% ± 2

12. A building product according to claim 1, wherein the cellulose is in the form of hydroxyethyl methyl cellulose.

13. A building product according to claim 1, wherein the cellulose is included within the binder.

14. A building product according to claim 13, wherein the cellulose is included within the cementitious product of the binder.

15. A building product according to claim 14, wherein the cellulose is included in the cementitious product in a proportion of between 0.5% and 5% of the total binder weight.

16. A building product according to claim 15, wherein the cellulose is included in the cementitious product in a proportion of between 0.5% and 1.5% of the total binder weight.

17-20. (canceled)

21. A building product according to claim 1, wherein the water reducing agent is calcium lignosulphanate.

22. A building product according to claim 21, wherein up to 1.5% calcium lignosulphanate solution is provided in the mixture prior to drying.

23. (canceled)

24. (canceled)

25. A building product according to claim 1, wherein the building product has a moisture content of between 0.3% and 2%.

26. (canceled)

27. (canceled)

28. A method of forming a building product according to claim 1, the method comprising mixing together the materials of the product and locating the mixture between two sheets of lining paper.

29. A method according to claim 28, wherein the material is extruded between the two sheets of lining paper.

30. A method according to claim 28, wherein the components of the binder are mixed together dry and then mixed with the water and the water reducing agent to form a slurry.

31. A method according to claim 28, wherein the water is heated before mixing.

32. (canceled)

33. (canceled)

34. A method according to claim 29, wherein heat is applied to the newly extruded composite shortly after the point of forming to decrease the initial set time, and the heat is applied via direct contact, through conduction in the forming belt, or indirectly through convection or infrared heat.

35. (canceled)

36. A method according to claim 28, wherein a retarder is included to delay setting of the materials.

37. A method according to claim 36, wherein the retarder is citric acid.

38. A method according to claim 28, wherein an accelerator is provided to accelerate setting of the materials.

39. A method according to claim 38, wherein the accelerator is sodium carbonate.

40-45. (canceled)

Description

[0048] Embodiments of the present invention will now be described by way of example only.

[0049] A building product in the form of an internal lining board is formed as follows. A natural cement including 1% by weight hydroxy ethyl methyl cellulose is mixed with hydrated lime.

[0050] Water is mixed with calcium lignosulphanate solution water reducing agent and mixed with the dry mix of cement and lime. These are combined and mixed to form a slurry. A food crop byproduct is mixed with the slurry, to form a paste.

[0051] The paste is distributed across a continuously moving belt onto a sheet of recycled paper lining material, and the paste is then extruded between the bottom layer of paper and a top layer of similar paper moving around a roller to provide a board of required thickness. The board may be subject to vibrating pads or rollers to ensure that it is flat and smooth. The lining paper is folded around the edges of the board.

[0052] Once the material in the board is hard enough it can be cut, for instance by a water jet cutter. The product will then be stacked in racking and taken to a drying chamber with a temperature of 20° C.+−2° C. and 50% RH+−10% RH for curing and drying, typically for 3 to 5 days. After drying the product, it should be ready for use.

[0053] The food crop byproduct may be any of the following, though this list should not be considered to be exhaustive: —

[0054] Common wheat (Triticum aestivum)

[0055] Hemp—Cannabis Sative

[0056] Oats—Avena sativa

[0057] Rapeseed (Brassica napus)

[0058] Barley straw

[0059] Giant Miscanthus (Miscanthus giganteus)

[0060] Bamboo

[0061] Flax

[0062] Rice straw

[0063] Corn straw

[0064] Sugarcane bagasse

[0065] Sisal straw

[0066] All of these products should have cellulose, hemi-cellulose and lignin and within the following proportions.

TABLE-US-00002 Cellulose 5-50% Hemi-cellulose 5-50% Lignin 8-30%

[0067] The particle size distribution within the material is important. In the first instance a majority of the particles should be less than a third of the thickness of the board, and substantially no particles should be greater than half of the thickness of the board.

[0068] The board thus produced should have a density of between 500 kg/m.sup.2 and 750 kg/m.sup.2

[0069] Three examples of board, are formed with the following proportions.

TABLE-US-00003 Materials Example 1 Example 2 Example 3 Cementitious product 41.5% 50.0% 36.2% including cellulose Hydrated Lime 38.0% 30.0% 33.3% Food crop byproduct 20.5% 20.0% 30.5%

[0070] The proportions of liquid components added to the above dry components are as follows:—

TABLE-US-00004 Materials Example 1 Example 2 Example 3 Water 49.3% 50.0% 55.0% Calcium lignosulphante 0.3% 0.1% 1.0% solution

[0071] The proportions of components in the finished products, with the binder including the cementitious product, cellulose and lime, are as follows:—

TABLE-US-00005 Materials Example 1 Example 2 Example 3 Binder 79.0% 79.8% 68.7% Food crop by product 20.0% 19.8% 29.8% Moisture Content 1.0% 0.4% 1.5%

[0072] Example 1 is a standard product. In Example 2 a greater proportion of cementitious product to hydrated lime is provided to increase hardness, sheer strength and compressive strength. Compressive strength and sheer strength for instance increase the ability for the product to take a screw. This increase in compressive strength will increase flexural rigidity.

[0073] Example 3 provides a more thermally and acoustically insulative product, with improved hygrothermal performance.

[0074] The finished products provide a paper faced lining board which can be cut to size by cutting the sheets with a knife and snapping the board within. The product can be attached to stud work or walls with screws in a conventional manner. The board can have square edges or tapered edges to permit jointing.

[0075] The products thus formed provide for commercial scale production of compostable materials which are fast setting. The drying process is without high temperatures or pressure and this helps to reduce the embodied energy and cost to make the product. The cellulose used has been found to improve the strength of the board and also create a bond between the paper and the board materials.

[0076] The inclusion of cellulose to the cementitious binder also improves the interface between the binder and the aggregate, creating a more structurally homogeneous composite. Conventional internal lining boards do not use compostable materials and can also use a high energy input during production. The product thus formed is lighter weight than conventional products, reducing health and safety risk at the point of installation, as well as embodied energy for transportation.

[0077] Various modifications may be made without departing from the scope of the invention. For instance retardants such as citric acid may be included if it is required to slow down curing, or accelerants such as sodium carbonate may be used if required to speed up curing. Air entraining agents may be used to improve flow of the paste in the process. Different drying conditions may be applied. The materials may be used in different proportions or combinations of those indicated. Other food crop byproducts may be suitable for use.

[0078] Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.