WO2009111844A1

WO2009111844A1 - Waterless construction materials and methods of making the same

Info

Publication number: WO2009111844A1
Application number: PCT/AU2009/000307
Authority: WO
Inventors: Bill Tassigiannakis; Edward N. Alexander
Original assignee: Bill Tassigiannakis; Alexander Edward N
Priority date: 2008-03-14
Filing date: 2009-03-16
Publication date: 2009-09-17

Abstract

Solid compositions, and methods of forming the same, which are suitable for use as a construction materials. The.compositions include a complex formed from reaction of a solid hydrated inorganic salt and a solid amide compound, for example, a sulphate-urea complex, a carbonate-urea complex, a borate-urea complex or a magnesium-urea complex. The water of hydration released from the reaction may be present, as may additives, such as for example a polymer compound such as polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, polyisocyanurates, polyvinyl chloride (PVC)3 polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters, polyimides and polystyrene.

Description

WATERLESS CONSTRUCTION MATERIALS AND METHODS OF MAKING THE

SAME

FIELD OF THE INVENTION The present invention relates to plaster-like materials and the manufacture thereof. The plaster-like materials are particularly suited for use as plasterboard, and will be described hereinafter with reference to that application.

The invention has been developed primarily for the formation of plasterboard and related materials without the use of free water. However;, it will be appreciated that the invention is not limited to this particular field of use.

BACKGROUND OF THE INVENTION

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Plasterboard products are well established as low-cost construction materials, generally . applied as internal lining boards to provide walls and ceilings within buildings. Plasterboard consists of a thin core of gypsum (CaSθ4.2H2θ) encased within heavy-duty cardboard sheets. The manufacture of standard plasterboard sheeting involves the mixing of gypsum with a significant quantity of water, followed by the addition of various solid and liquid admixtures until a homogenous slurry is obtained. The slurry is then sandwiched between two layers of heavy-duty cardboard, the edges of the cardboard being glued together to enclose the core. The two layers of cardboard are passed between two rollers, which compress the wet plasterboard to the desired thickness. The wet plasterboard is dried in a significantly energy intensive process before being cut into standard size sheets. There are well-known limitations associated with the manufacture of plasterboard products. The manufacture of standard plasterboard sheeting requires large quantities of water to be added to gypsum to produce a homogenous slurry to be encased within the sheeting. As such, large quantities of energy are then required to dry finished plasterboard. In large-scale manufacturing, this involves the use of gas fired heating to produce large volumes of heated air, which passes over the plasterboard to enable the rapid evaporation of water combined in the freshly formed plasterboard. This necessitates large capital outlay, and hence cost, for current manufacturing plants and limits the productivity of the manufacturing process.

Additional problems are associated with the installation and use of the plasterboard as a construction material. Large quantities of dust are created when conventional plasterboard is sanded or cut. Further, it cannot be readily fashioned to provide curved boards/surfaces and metal brackets are required to mount electrical switches in standard plasterboard sheeting.

. The properties of standard plasterboard are limited by low durability, due to the hydrophilic nature of gypsum. Standard plasterboard is susceptible to weakening by exposure to water, such as in areas of humid climates and in common rooms such as kitchens and bathrooms in urban dwellings. The properties, of current plasterboard products are thus limited in terms of strength and water resistance, as well as other properties including acoustic insulation, resistance to damage by fire and dimensional stability.

It is known in the art to improve the strength and water resistance of gypsum plasterboards through the addition of hydrophobic polymers to the gypsum admixture. US

6,492,450 to Hsu, for example, discloses the addition of a hydrophobically modified monomer (an alkyl ester of methacrylic acid) to gypsum and claims to provide water resistance to the gypsum plasterboard, preferably without weakening the same. However, this solution does not address the problem of the large quantity of water required to produce the plasterboard, as water is still used to create the slurry of gypsum and polymer, and, as such, the drying of the plasterboard still remains significantly energy intensive.

US 7,105,587 to Tagge et al also discloses the use of an organic strengthening component (polyvinyl pyrrolidone), and a crosslinking component (polystyrene sulphonate) in the presence of hydrated gypsum to create a mixture which is thereby added to water to form a slurry. The organic strengthening component is crosslinked causing it to form a gel. The stated aim of US 7,105=587 is to produce lightweight, strong, wear and water resistant plasterboard products along with the need to improve plasterboard properties such as thermal and sound insulation while providing reduction in the costs associated with the shipping and installation of conventional plasterboard. However, water is still required in the manufacture of the product in a more complex manufacturing process than for standard plasterboard and drying of the resulting plasterboard product is still required. In addition, a crosslinked material is produced that is unable to be recycled by conventional re-extrusion methods.

Substantially waterless cement containing mixtures have been disclosed in the art, for example, in US 5,384,355 for use as a polymer concrete pipe liner. These are specifically used as liners for pipes exposed to harsh chemical and high temperature environments. A liquid composition comprising styrene and one or more reactive unsaturates is present in the composition to assist in the formation of a slurry. This reacts covalently to form a thermoset material containing concrete particles., The composition is not able to be extruded and is unable to be recycled by conventional re-extrusion methods. Such an application is not applicable to more general construction material such as plasterboard, and still requires capital outlay for the ^' mixing of liquid and solid components. Additionally, such a composition would suggest toxicity and environmental concerns if used in an internal application in an urban environment.

There remains a need for a simple, low cost process to manufacture plasterboards and other related building products without the requirement for a large capital outlay while producing a strong, waterproof product that produces limited dust and can be easily fashioned to produce complex structures.

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative. .

SUMMARY OF THE INVENTION

According to a first aspect, the invention provides a solid composition suitable for use as a construction material including: a complex formed from, reaction of a solid hydrated inorganic salt and a solid amide compound.

Preferably, the composition includes water of hydration released from the reaction. The complex is preferably a sulphate-urea complex, a carbonate-urea complex, a borate urea or a magnesium-urea complex.

According to a second aspect, the invention provide a solid composition suitable for use as a construction material including: . ^ a complex formed from reaction of a solid hydrated inorganic salt and a solid amide compound; water of hydration released from said reaction; and a polymer compound. Preferably, the complex is a sulphate-urea, carbonate-urea or borate urea complex. The complex is a magnesium-urea complex in the preferred embodiment. The complex may be a single chemical entity (ie a single discrete compound) or a mixture of compounds.

The polymer is preferably selected from at least one of the compounds of the group consisting of polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), poiyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, polyisocyanurates, polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters, polyimϊdes and polystyrene. In the preferred embodiment, the polymer is ethylene/acrylic acid copolymer.

According to^" a third aspect, the invention provides a method for making a solid material including the steps of: combining a solid hydrated inorganic salt and a solid amide compound under conditions causing said salt and said amide to react and release water of hydration to form a slurry; and allowing said slurry to solidify. Preferably, the hydrated inorganic salt is an inorganic sulphate, carbonate or borate salt or similar cementitious materials. More preferably, the hydrated inorganic salt hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate. The amide compound is preferably carboxamide (urea).

According to a fourth aspect, the invention provides a method for making a solid material including the steps of: combining a solid hydrated inorganic salt, a solid amide compound under conditions causing said salt and said amide to react and release water of hydration to form a slurry; and allowing said slurry to solidify, and wherein the solid material further includes an additive.

The additive is preferably a polymer compound, but may be other material, such as plant materials or minerals, or combinations thereof, eg plant fibre plus polymer.

The additive may be added before or after the reaction between the salt and the amide, but is preferably added before the slurry solidifies. The additive is preferably, but not necessarily, dispersed evenly through the solid material. The hydrated inorganic salt is preferably an inorganic sulphate, carbonate or borate salt or similar cementitious materials. The hydrated inorganic salt is hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate in the preferred embodiment. The amide compound is preferably carboxamide (urea). In some embodiments, the polymer is a polyolefm compound. In alternative embodiments, the polymer is an elastomeric polymer. The polymer is preferably selected from at least one of the compounds of the group consisting of polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, polyisocyanurates, polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters, polyimides and polystyrene. In the preferred embodiment, the polymer is ethylene/acrylic acid copolymer.

According to a fifth aspect, the invention provides a solid construction material formed from the method according to any one of the previous aspects.

According to a sixth aspect, the invention provides an article for use as a construction material including: a composition including a solid hydrated inorganic salt and a solid amide compound. The hydrated inorganic salt is preferably an inorganic sulphate, carbonate or borate salt or similar cementitious materials and is hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate in the preferred embodiment. The amide compound is preferably carboxamide (urea).

According to a seventh aspect, the invention provides an article for use as a construction material including: a composition including a solid hydrated inorganic salt, a solid amide compound and a polymer compound. Preferably, the hydrated inorganic salt is an inorganic sulphate, carbonate or borate salt or similar cementiticms materials, more preferably hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate. The amide compound is preferably carboxamide (urea) and the polymer is selected from at least one of the compounds of the group consisting of polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, polyisocyanurates, polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters, polyϊmides and polystyrene. In a preferred embodiment, the polymer is ethylene/acrylic acid copolymer. According to an eighth aspect, the invention provides an article for use as a construction material including: a composition including a solid hydrated inorganic salt, a solid amide compound and a polymer compound wherein said composition substantially consists of the complex generated by reaction between said hydrated inorganic salt and said amide compound such that said polymer is a minor constituent.

According to a ninth aspect, the invention provides an article for use as a construction material including: a composition including a solid hydrated inorganic salt, a solid amide compound and a r polymer compound wherein said composition substantially consists of said polymer such that the complex generated by reaction between said hydrated inorganic salt and said amide is a minor constituent.

In some embodiments, the article further includes a flame retardant compound such as magnesium hydroxide, aluminium trihydroxide and the like,, and an inorganic filler including calcium sulphate dihydrate, calcium carbonate, sodium borate and the like. In alternative embodiments, the flame retardant compound excludes halogen compounds. Another alternative - S - embodiment further includes a thermoplastic polymer such as polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, polyisocyanurates, polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters, polyimides and polystyrene. These articles can be made to any predetermined desired density. The density of these articles is typically between approximately 270kg/m³ and approximately 2600kg/m³.

In alternative embodiments, articles can be manufactured by incorporating compositions of the present invention into existing construction materials to enhance or increase properties such as stiffness, flexibility, resilience, acoustic and thermal dampening of the existing construction material. In still further embodiments, articles can be manufactured by incorporating composition of the present invention along with reusable waste (such as off-cuts) from conventional construction materials to produce articles having improved properties and/or reduced costs.

According to a tenth aspect, the invention provides plasterboard formed from an article according to any one of sixth to ninth aspects wherein the plasterboard can be recycled using conventional re-extrusion technologies.

According to an eleventh aspect, the invention provides use of a composition according to any one of the sixth to ninth aspects to form plasterboard construction material and the like. According to a twelfth aspect, the invention provides use of a composition according to any one of any one of the sixth to ninth aspects to form a membrane film construction material. According to an thirteenth aspect, the invention provides use of a composition according to any one of any one of the sixth to ninth aspects to form a designed article for use in building construction.

DESCRIPTION OF THE DRAWINGS Figure 1 shows data obtained from a cone calorimeter test of sample E of the present Invention. Figure 2 shows the sound reduction index of a polymer based construction material of the present invention.

Figure 3 is a table showing cone calorimeter studies of pressed plaques of the material of the present invention.

DETAELED DESCRIPTION

The invention will now be described particularly in relation to the manufacture of a structural construction material without the use of free water. Although the invention will be described with reference to specific examples, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms. These additional forms include, but are not restricted to, wire and cabling applications, injection moulding applications and decorative/lighting fixtures.

The present invention provides a method of producing plasterboard and other related building products without the need for the use of large quantities of free water and energy (heat) required in the current methods of producing plasterboard. This invention removes the need to add free water to the gypsum-based product in order to make plaster slurry and also removes the need for large quantities of heat energy to dry the finished, wet plasterboard product.

In one embodiment, the compound used for the formation of a solid construction material in the present invention is used in a simple, low cost process to make standard plaster and plasterboards according to the current techniques. A solid, hydrated inorganic salt, preferably a hydrated sulphate, carbonate or borate salt, preferably hydrated magnesium sulphate (MgSO₄JH₂O) in this particular embodiment, is combined and ground together with an amide, preferably carboxamide (urea — NH₂CONH₂) to enable reaction between the two / compounds. Under the atmospheric temperature and pressure conditions of the present invention in this embodiment, and upon application of an external force, a hydrated sulphate, such as magnesium sulphate, reacts with urea molecules according to the following chemical reaction:

MgSO₄.7H₂O + 6NH₂CONH₂ -> MgSO₄^CO(NH₂) 2 + 7H₂O. A sulphate-urea complex is formed upon the combination of the two solid reactants, with the application of an- external force to enable the reaction, as shown above. Water of hydration molecules become free in liquid form, which can then be used to form slurry as required. The mixture can then be formed into plasterboard and plaster based products according to standard techniques. ^' In an alternative embodiment, organic flame retardants and inorganic fillers can be incorporated into the hydrated sulphate/urea mixture, including calcium sulphate dihydrate, to impart improved physical or chemical properties to the final article, such as sound dampening and flame retardation.

It is known in the art that the reaction between calcium sulphate dihydrate and urea is very slow and greatly depends on relative humidity at atmospheric pressure and temperature. It is also known that the separation of free water can be observed at a high pressure of 3000 kg/cm². (Kiyama et al Chemical Reactions under Ultra High Pressure. Reaction between Urea and Gypsum. The Review of Physical Chemisty of Japan. VoI 22. No. J (1952). Pages 39-42). Without wishing to be bound by theory, the present inventor has found that when various inorganic salts are ground together with an amide compound, such as urea, a reaction takes place under atmospheric conditions to generate free water of hydration molecules, thereby producing a construction material which may be set in the desired form without the need for additional water, other than that generated by the reaction. This allows the use of current plasterboard manufacturing techniques with the benefit of a simple process without the need for additional capital outlay to supply liquid components to the reaction and removes (but does not preclude) the need to supply heat energy to drive off excess water from the finished plasterboard product.

The setting time of the finished product(s) will also vary depending on external factors such as temperature and relative humidity applied and can vary from a number of minutes to up to several hours.

Additionally, formulations including inert fillers, UV stabilisers, antioxidants, oil, extenders, processing aids and minor quantities of other materials and combinations thereof can be added into the mixture to assist with the manufacture and/or the final physical and chemical properties of the plasterboard or plaster based products. In an alternative embodiment, the basic reaction between the inorganic salt and amide compound is used in combination with various polymeric materials, such as ethylene-acrylic acid copolymer, to make a construction material with improved properties. These properties include improved strength, durability, sound dampening and flame resistance. The combination with polymeric material can also assist in the flexibility of processing the finished material and allow the finished material to be easily moulded into difficult shapes. The ratio of polymer to inorganic salt/amide will vary depending on the properties required in the final product, but can be anywhere from 99.9% to 0.1% to 0.1% to 99.9%. Typically, the percentage of inorganic salt/amide can vary from very low to as high as 80%.

For example, a sample of construction material (Sample E) made using the methods described was designed specifically on the basis of flame retardation properties. Sample E has the following composition:

Sample E: 26% magnesium/urea complex, 42% calcium sulphate, 15% barium sulphate, 14% Dow Versify 3300 (polypropylene/ethylene copolymer), 3% Dow Primacor (ethylene/acrylic acid copolymer). The results of the sample testing in a cone calorimeter are shown in the following Figure 1.

As shown in the first chart of Figure 1, the peak heat generation rate of Sample E is 95 kW/m². The material of Sample E is described as a "slow burn" material when compared to a peak heat generation rate of 150 - 200 kW/m² for wood and typical polymer based materials.

With regards to sound dampening, results are given in Figure 2, showing the sound reduction index of a polymer based construction material, consisting of a calcium carbonate/urea complex, polypropylene/ethylene copolymer and an ethylene/acrylic acid copolymer, compared to the sound reduction of a standard plasterboard made using current techniques. These results indicate significant sound reduction compared to the standard plasterboard at frequencies greater than 2500Hz.

While the polymer used in the present invention can be formed from a broad range of suitable polyolefin compounds, such as polypropylene and polyethylene, the polymers of the present invention are preferably formed from polymeric elastomers, providing the final article with the property of elasticity. The elasticity of the material is derived from the ability of the polymer chains to reconfigure in order to distribute an applied stress. Polymer chain entanglement and/or crosslinking present in the polymer ensures that the elastomer returns to its original configuration when the stress is removed. The applied stress would result in a permanent deformation in the absence of cross-linking or with short, uneasily reconfigured polymer chains. Preferred elastomers of the present invention include polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, silicon and organo silicon polymers, and fLuoro polymers.

In a further embodiment, the ratio of the composition used to produce the final construction material can be altered to consist largely of polymer, preferably an elastomeric polymer, with as significant percentage of additional filler content. The ratios of chemicals present in the composition can be significantly altered depending on the final properties required of the finished product As an example, thin sheets can be manufactured with significant sound dampening properties as well as flame resistance for use in extremely high-density living.

The construction materials of the present invention are not restricted to sheeting. The composition of the present invention can be used to form, for example, films, membranes, wood/timber substitutes or designed articles. Complex moulded fixtures such as ceiling roses can be formed from the composition of the present invention without the need for a complex process involving excess water and heat.

The compounds of the present invention have been extruded into a range of forms with measured densities ranging from between 272kg/m³ to 2533kg/m³.

In a further embodiment, the construction material is made from a composition of an inorganic salt, preferably a metal carbonate, an amide compound, preferably urea, and a polymer compound, preferably ethylene-acrylic acid copolymer, wherein the polymer is used during the manufacturing process to form an expanded polymeric foam region within the construction material. This can be used to reduce the weight of the material or to create a low-density material.

In the present invention, existing polymeric micro-pellet technology is used to make micro-pellets that are used as precursor for construction of a polymer-based foam within the final construction material product using a moulding process. A full range of polymeric materials, fillers, additives and blowing agents, are used to produce the micro-pellets and to fine tune the final physical properties of the foam region that is subsequently produced from these micro -pellets.

To produce the polymeric foam region with the final construction material product, the polymeric material is combined with a blowing agent and additives, if desired, including fillers, dyes for colour, UV-stabilisers etc, and formed into micro-pellets. The micro-pellets are then heated in any one of a variety of moulding processes including rotomoulding, rotofoarning, injection moulding, blow moulding extrusion, co-extrusion, or combinations thereof. It will be appreciated that the use of polymers and polymeric foam regions in the final construction material can be used in. a variety of forms, including sheeting, films, membranes and designed articles for use in construction. These articles can be made from a composition consisting substantially of the inorganic salt/amide complex or from a composition consisting substantially of polymer.

Rigid and flexible foam constructs manufactured from the compositions of the invention have acoustic benefits, thermal insulation/modulation, and a selection of inorganic components to make the construction materials flame retardant (FR) (see Table 1).

Compounds of the invention have also been made into sheets of construction material that incorporated natural fibres (eg. husks, fibres, coconut coir) as well as synthetic fibres (eg. Kevlar). These sheets of materials have a measured sheet density between the values of 0.93 kg/m² and 3.1 kg/m². In a further alternative embodiment, compounds of the invention have been used to produce end products with a range of different forms, such as micro-pellets, fibres, or ground powder, that have been incorporated into existing building constructs to enhance or impart additional properties as required. For example, micro-pellets have been incorporated into conventional plasterboard to increase impact performance, sound deadening, and to make a lighter or heavier construct than is currently produced with conventional plasterboard technology. These combination constructs can be made to produce structures with desirable physical properties such as stiffness, flexibility and resilience.

In yet another embodiment, off-cuts from conventional construction material production have been blended with compounds of the present invention to produce recycled construction material such as plasterboard with improved strength and resiliency properties. Compounds of the invention have been shown in practice to have good adhesion to substrates such as metal, wood, paper, foil, as well as polyolefin and polar plastic sheets and films.

It will be appreciated that the illustrated method and composition used to produce construction materials removes the need for the addition of free water and the need for large quantities of energy to dry the finished material.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A solid composition suitable for use as a construction material including: a complex formed from reaction of a solid hydrated inorganic salt and a solid amide compound.

2. A solid composition according to claim 1 including water of hydration released from said reaction.

3. A solid composition according to claim 1 or claim 2 wherein said complex is a sulphate-urea complex, a carbonate-urea complex, a borate-urea complex or a magnesium-urea complex.

4. A solid composition suitable for use as a construction material including: a complex formed from reaction of a solid hydrated inorganic salt and a solid amide comppund; water of hydration released from said reaction; and an additive.

5. A solid composition according to claim 4 wherein said complex is a sulphate-urea complex, a carbonate-urea complex or a borate-urea complex.

6. A solid composition according to claim 4 or claim 5 wherein said complex is a magnesium- urea complex.

7. A solid composition according to any one of claims 4 to 6 wherein said additive is a polymer selected from at least one of the compounds of the group consisting of polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldeh^'yde, ethylene/acrylic acid copolymer, polyisocyanurates, polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligpesters, polyimides and polystyrene.

8. A solid composition according to claim 7 wherein said polymer is ethylene/acrylic acid copolymer.

9. A method for making a solid material including the steps of: combining a solid hydrated inorganic salt and a solid amide compound under conditions causing said salt and said amide to" react and release water of hydration such that a slurry is formed; and allowing said slurry to solidify.

10. A method according to claim 9 wherein said hydrated inorganic salt is an inorganic sulphate, carbonate or borate salt or similar cementitious materials.

11. A method according to claim 9 or claim 10 wherein said hydrated inorganic salt is hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate.

12. A method according to any one of claims 9 to 11 wherein said amide compound is carboxamide (urea).

13. A method for making a solid material including the steps of: combining a solid hydrated inorganic salt, a solid amide compound under conditions causing said salt and said amide to react and release water of hydration to form a slurry; and allowing said slurry to solidify and wherein the solid material further includes a polymer compound.

14. A method according to claim 13 wherein said hydrated inorganic salt is an inorganic sulphate, carbonate or borate salt or similar cementitious materials.

15. A method according to any one of claim 13 or claim 14 wherein said hydrated inorganic salt is hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate.

16. A method according to any one of claims 13 to 15 wherein said amide compound is carboxamide (urea).

17. A method according to any one of claims 13 to 16 wherein said polymer is a polyolefin compound.

18. A method according to any one of claims 13 to 16 wherein said polymer is an elastomeric polymer.

19. A method according to claim 17 or claim 18 wherein the polymer is selected from at least one of the compounds of the group consisting of polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea- formaldehyde, ethylene/acrylic acid copolymer, polyisocyanurates, polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters, polyimides and polystyrene.

20. A method according to claim 19 wherein said polymer is ethylene/acrylic acid copolymer.

21. A solid construction material formed from the method according to any one of the preceding claims.

22. An article for use as a construction material including: a composition including a solid hydrated inorganic salt and a solid amide compound.

23. An article according to claim 22 wherein said hydrated inorganic salt is an inorganic sulphate, carbonate or borate salt or similar cementitious materials.

24. An article according to claim 22 or claim 23 wherein said hydrated inorganic salt is hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate.

25. An article according to any one of claims 22 to 24 wherein the amide compound is carboxamide (urea).

26. An article for use as a construction material including: a composition including a solid hydrated inorganic salt, a solid amide compound and an additive.

27. An article according to claim 26 wherein said hydrated inorganic salt is an inorganic sulphate, carbonate or borate salt or similar cementitious materials.

28. An article according to claim 26 or claim 27 wherein said hydrated inorganic salt is hydrated magnesium sulphate, calcium sulphate dihydrate, hydrated calcium carbonate or hydrated sodium borate.

29. An article according to any one of claims 26 to 28 wherein the amide compound is carboxamide (urea).

30. An article according to any one of claims 26 to 29 wherein said additive is a polymer selected from at least one of the compounds of the group consisting of polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, polyisocyanurates. polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters. polyimides and polystyrene.

31. An article according to claim 30 wherein said polymer is ethylene/acrylic acid copolymer.

32. An article for use as a construction material including: a composition including a solid hydrated inorganic salt, a solid amide compound and an additive wherein said composition substantially consists of the complex generated by reaction between said hydrated inorganic salt and said amide compound such that said additive is a minor constituent.

33. An article for use as a construction material including: a composition including a solid hydrated inorganic salt, a solid amide compound and an additive wherein said composition substantially consists of said additive such that the complex generated by reaction between said hydrated inorganic salt and said amide is a minor constituent.

34. An article according to claim 33 further including a flame retardant compound such, as magnesium hydroxide, aluminium trihydroxide and the like, and an inorganic filler including calcium sulphate dihydrate, calcium carbonate, sodium borate and the like.

35. An article according to claim 34 wherein said flame retardant compound excludes halogen compounds.

36. An article according to any one of claims 33 to 35 further including a thermoplastic polymer such as polypropylene, polyethylene, polyurethane, ethyl vinyl acetate (EVA), polyurea, polyurea-formaldehyde, ethylene/acrylic acid copolymer, polyisocyaaurates, polyvinyl chloride (PVC), polyepoxides, silicon and organo silicon polymers, fluoro polymers, phenolic oligoesters, polyimides and polystyrene.

37. An article according to any one of claims 22 to 36 wherein density of said article is between approximately 270kg/m³ and approximately 2600kg/m³.

38. An article according to any one of claims 22 to 37 wherein said article manufactured by incorporation of said composition into existing construction material to increase stiffness, flexibility and resilience of said material.

39. An article according to any one of claims 22 to 38 wherein said article is manufactured by incorporation of said composition into off-cuts from conventional construction material production.

40. Plasterboard formed from an article according to any one of claims 22 to 39 wherein said plasterboard can be recycled using conventional re-extrusion technologies.

41. Use of an article according to any one of claims 22 to 39 to form plasterboard construction material and the like.

42. Use of an article according to claim 41 to form boards, synthetic wood products for architraves and skirting and moulded plaster products.

43. Use of an article according to any one of claims 22 to 39 to form a membrane film construction material.

44. Use of an article according to any one of claims 22 to 39 to form a designed article for use in building construction.

45. A solid composition suitable for use as a construction material substantially as herein described with reference to the accompanying examples.

46. A method for making a solid material substantially as herein described with reference to the accompanying examples.

47. A solid construction material formed from the method of any one of claims 9 to 20 substantially as herein described with reference to the accompanying examples.

48. An article for use as a construction material substantially as herein described with reference to the accompanying examples.

49. Plasterboard formed from an article according to any one of claims 22 to 39 substantially as herein described with reference to the accompanying examples.

50. Use ofan article according to any one of claims 22 to 39 to form plasterboard construction material and the like substantially as herein described with reference to the accompanying examples.

51. Use ofan article according to any one of claims 22 to 39 to form a membrane film construction material substantially as herein described with reference to the accompanying examples.

52. Use ofan article according to any one of claims 22 to 39 to form a designed article for use in building construction substantially as herein described with reference to the accompanying examples.