A Building Panel and a Method of Making a Building Panel

The invention relates to a building panel and a method of making a building panel.

The outer walls of houses are conventionally built using breeze blocks laid with mortar. An additional, outer skin of bricks may then be laid with mortar. Inside the house the wall will be lined with plasterboard and then plastered to be ready to receive paint or wallpaper. The internal walls of a house will conventionally be of less substantial construction and will be lined on each side with plasterboard and plastered.

Housing demand in the United Kingdom currently exceeds housing supply by 55,000 houses a year. There is also a shortage of skilled labour.

The use of recycled materials in the construction of buildings is desirable, as it allows the environmental impact of construction to be reduced. However, at present, recycled materials are incorporated only into building elements such as bricks and blocks. It would be advantageous to have other building elements incorporating recycled materials.

In accordance with a first aspect of the invention there is provided a building panel comprising a base panel made of a material including a binding material and a recycled material, wherein the base panel comprises a load-bearing core.

The use of recycled materials in the manufacture of the building panels is advantageous, as it reduces environmental impact. However, there has been a technical prejudice

against the use of recycled materials in building panels, and so they have been used only in smaller building elements such as bricks and blocks. The provision of the load-bearing core in a building panel incorporating recycled materials allows the building panel to be used in a load-bearing wall of a building. Further, the building panels can be mass produced allowing cheaper and easier construction of building incorporating recycled materials.

The load-bearing core may be a concrete lattice.

Preferably the concrete lattice is reinforced with steel rods. This provides a convenient load-bearing structure. The load-bearing core may also be a composite lattice, for example comprising a mixture of lime and crushed eggshells.

Alternatively, the load-bearing core may be a metal lattice. Preferably the load-bearing core comprises metal rods .

In an advantageous alternative, the load-bearing core comprises recycled plastics material. The use of recycled material for the load-bearing core allows the environmental impact of the building panel to be further reduced.

Preferably the binding material is lime. However, any other suitable binding materials could also be used, for example cement or a mixture of lime and cement.

The recycled material may comprise paper product or card product. Advantageously, the paper product or card product is from waste paper or waste card. The use of waste paper or card for the present invention is particularly advantageous as waste paper or card which includes for example ink, gum for sealing envelopes or plastic as used in envelope windows

can be used. Preferably, the amount of paper product or card product in the base panel is about 70wt%.

Alternatively, the recycled material may comprise or hemp, wood, chipboard and/or sawdust.

Advantageously, the binding material further comprises sand and/or crushed glass. The use of these materials allows the environmental impact of the building panel to be further reduced.

The building panel may further comprise a layer of gypsum based material bonded to at least one major side of the base panel . Advantageously, the gypsum based material is from waste plasterboard.

Preferably, the building panel further comprises a waterproof vapour barrier. Advantageously, the waterproof vapour barrier comprises recycled plastics material.

Advantageously, the building panel is arranged to form at least the major part of a wall.

In accordance with a further aspect of the invention there is provided a method of making a building panel comprising a base panel and a load-bearing core, comprising the steps of: taking a load-bearing core, assembling a mould around the load-bearing core, introducing a slurry of a binding material and a recycled material into the mould to contact the load-bearing core, hardening the slurry to form the base panel of the building panel.

Preferably, the base panel is built up in a plurality of layers, each layer being formed by introducing a quantity of slurry to the mould and hardening the slurry to form the layer before the next quantity of slurry is introduced for the next layer.

Advantageously, the mould is a double sided mould, a first part of the base panel is formed and hardened, the part-formed base panel incorporating the load-bearing core is turned over, and then a second part of the base panel is formed and hardened.

The following aspects of the invention are also envisaged:

According to one aspect of the invention there is provided a building panel comprising a base panel made of a material including cement and paper product or card product, and a layer of gypsum based material bonded to at least one major side of the base panel.

The use of paper or card product in the panel reduces the weight of the panel compared with a concrete panel but also increases both thermal insulation and sound insulation. There has been a technical prejudice against the use of paper and card product in house walls because of fears of the risk of fire. In fact the base panel made of the material comprising cement and paper product or card product will smoulder, but not catch fire. Furthermore, gypsum is a non- combustible material and so the layer of gypsum based material provides a fire resistant barrier. The layer of gypsum based material also results in a building panel which is a laminate composite of superior strength. The layer of

gypsum based material gives the surface improved resistance to accidental mechanical damage or abuse. The building panel is a single piece for erection thus reducing the need for skilled labour and reducing build time. The building panel of the invention can be made in the standard building sizes.

The base panel forms the major part of the building panel and the layer of gypsum based material forms a minor part of the building panel.

The building panel is preferably arranged to form at least the major part of a wall.

The paper or card product is preferably from waste paper or waste card. The United Kingdom generates 7,000,000 tonnes of waste paper per year and only 40% of this is recovered. The recycling of 1 tonne of paper will save 3, 000 litres of drinkable water and between 3,000 and 4,000 kW of electricity, enough to supply a three bedroom house for a year. Recycling in this way also reduces the amount of waste going to landfill, or being incinerated with the consequent pollution to the atmosphere, and in particular C02 emission.

The amount of paper or card product in the base panel may be at least 5wt%, preferably at least 30wt%, more preferably at least 50wt%. In a preferred embodiment, about 70wt% of the base panel is paper or card product.

The paper or card product may be in the form of fibres. The fibre length is preferably less than 5mm.

The gypsum based material may be any suitable material but preferably the gypsum based material is from waste plasterboard. About 3,000,000 tonnes of plasterboard are

used in construction in the United Kingdom each year, and it is estimated that some 300,000 tonnes of plasterboard waste is generated each year from new construction activity, largely as offcuts. The use of waste plasterboard in this invention reduces the amount of waste which is put into landfill. Plasterboard has a paper lining. The gypsum based material from waste plasterboard may thus be a mixture of gypsum and paper.

According to a further aspect of the invention there is provided a building panel comprising a cement based panel clad on at least one major surface with a layer of material made from waste plasterboard.

The base panel may be made of a material which in addition includes an aggregate material. The aggregate material may be any suitable material, such as sand, but in a preferred embodiment the aggregate material includes glass particles. The glass particles are preferably from crushed waste glass. In particular, the glass particles may be from crushed waste plate glass. The total amount of flat glass waste in the United Kingdom is up to 500,000 tonnes each year. In one embodiment of the invention, as much as 20vol% of the material is glass particles.

According to a further aspect of the invention there is provided a building material made from cement and waste glass particles .

Glass particles improve the sound insulation properties of the material.

The use of these different waste materials can reduce the carbon footprint of a build.

The layer of gypsum based material may be bonded to only one major surface of the base panel, and in that case another protective layer may be attached to the opposite major surface of the base panel. Alternatively, a layer of gypsum based material may be bonded to both major surfaces of the base panel, and in that case the base panel may be used as an internal wall.

The building panel may be a load bearing panel.

The base panel preferably includes reinforcement. The reinforcement may take any suitable form and, for example, may be in the form of rods or a lattice. The reinforcement may be made of any suitable material. In one embodiment the reinforcement is made of concrete. In another embodiment, the reinforcement is made of metal and may take the form of metal rods or a wire mesh or grid. Both concrete and metal reinforcement may be present in the base panel.

According to another aspect of the invention there is provided a method of making a building panel comprising taking a base panel made of a material including cement and paper product or card product, assembling a mould around a major face of the base panel, introducing a slurry of a gypsum based material into the mould to contact the major face of the base panel, and hardening the slurry to leave a layer of gypsum based material bonded to the major face of the base panel.

This method creates a strong bond between the gypsum based material and the base panel.

Preferably the slurry is a slurry of pulverised plasterboard. In one embodiment, the slurry is sieved to remove the larger pieces of paper.

The gypsum based layer may be at least 5mm thick and preferably is at least 10mm thick.

The base panel may include a plurality of cavities. Such cavities improve insulation.

The base panel may include at least one passageway therethrough from one minor surface to another minor surface. In this way cables or pipes may be housed within the base panel .

The method of making the building panel may further include the step of making the base panel by forming a slurry of material including cement and paper product or card product, introducing the slurry into a mould and hardening the slurry. At least one inflatable bag may be introduced into the mould prior to introduction of the slurry in order to form at least one cavity within the panel. The or each bag may be inflated to hold its shape. The or each bag may be generally flat. The or each bag may have differing inflated thickness from one side to the other, for example, in the nature of a plastic bag for making ice cubes.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is an end elevation of a building panel;

FIG. 2 is an end elevation of a second building panel;

FIG. 3 is an end elevation of a building panel in accordance with a first embodiment of the invention; and

FIG. 4 is an end elevation of a building panel in accordance with a second embodiment of the invention; FIG. 5 is an exploded perspective view of a building panel in accordance with a third embodiment of the invention;

FIG. 6 is an exploded perspective view of the building panel of the third embodiment showing a number of possible finishes; FIG. 7 is an end elevation of the building panel of the third embodiment incorporating one of the possible finishes.

The building panel 10 shown in FIG. 1 comprises a base panel 20 with a layer 5 bonded to both major surfaces 8, 9 of the panel 20.

In order to make the panel of FIG. 1, a fibre cellulose mortar 2 is firstly prepared. The fibre cellulose mortar 2 includes waste paper pulped to cellulose fibres with a fibre length of less than 5mm. The mortar 2 comprises paper pulp, pulverised recovered flat glass and cement in the ratio of 7:2:1 by volume, water also being added.

Additives including a rapid hardener, agglutinants and plasticizers are added to the mortar in small amounts to give the final product smoother finishing as well as speeding up the manufacturing process. Additives can also improve the stability of the mortar and its waterproof properties.

In order to form the base panel 20, the mortar 2 is introduced into a mould (not shown) . The mortar 2 is mixed in a conventional cement mixer (not shown) together with water. The mortar 2 is poured into the mould to form a poured layer approximately 20mm thick. This layer is

manually compressed, and then the next layer is poured. Alternatively, the layer may be mechanically compressed. A grid of steel rods 6 which may be about 6mm diameter is positioned on top of the second layer of mortar 2. A further layer is then poured and manually compressed. Again, the layer may alternatively be mechanically compressed. An expanded metal mesh 15 is placed on the mortar 2 to cover the whole of the surface and one further layer of mortar 2 is poured on top. Service distribution trunking 7 for electricity cables and the like is then positioned on top of the mortar 2 to run from one side of the mould to the other. Two further layers of mortar 2 are then poured and compressed. The base panel 20 is then left to dry for up to fifteen days. Alternatively, the base panel 20 may be dried in an autoclave to give a quicker drying time. The thickness of the base panel 20 is about 150mm.

The layer 5 is then formed. Waste plasterboard in the form of offcuts or complete boards are pulverised together with their paper lamination in a KDS grinder dryer, for example. This dry mixture is sieved to remove any large pieces of paper, say longer than 5mm, and is then mixed with water. The resultant slurry is poured over a major face 8 of the base panel 20. This layer of slurry is then left to dry for about 24 hours (or less if dried in an autoclave) . The procedure is then repeated on the opposite major surface 9 of the base panel 20. The slurry is applied to result in a gypsum based layer of thickness 12mm. This will give a 90 minute fire resistance rating.

The side surfaces 12 of the building panel 10 are stepped 14. In this way, two adjacent building panels 10 will engage with one another on assembly.

In use, the building panel 10 can be used to form an internal wall or partition which is not load bearing. The building panels 10 can be delivered to site and connected to load bearing structures in the usual way, being interengaged with one another by the stepped side surfaces 12 to form a complete wall. The outer surfaces 16 of the layers 5 are smooth and ready to accept paint or wallpaper. Skirting board can be added at the foot of the wall if desired. Bores to intersect the trunking channel 7 can be drilled into the building panel 10 to enable, for example, light switches to be fitted. Indeed, once a building panel 10 is dry, part of it may be cut away to receive an internal door and door frame so that the building panel complete with door can be supplied to site which will clearly reduce the time required on site to complete the building. Similarly the building panel 10 may be supplied with a window already fitted into it.

The building panel 10 may thus be the floor to ceiling height of the building in which it is to be fitted, and hence may be typically between, say, 2.3m and 2.7m in height. The building panel 10 may be as wide as required, from say 0.8m to several metres in width.

The waste paper product or card product used in the mortar 2 can be of any type. Thus, ink on the paper will not affect the end product. Envelopes can be used, including window envelopes. The gum for sealing of the envelope is not a problem and indeed is beneficial in bonding of the mortar. Equally the plastics film of the envelope window is not a problem. Where paper is being recycled, envelopes generally are not recyclable because of the presence of the gum to seal the envelope. If the envelope has a plastics window again it cannot be readily recycled, as the plastics window would have to be separated from the paper and removed. Foil and/or

plastic coated card, of the type used in fruit juice cartons, can also be used in the mortar 2. The metallic layer constituting the foil will provide additional strength in the mortar and does not lead to any undesired chemical reaction in the composition of the mortar 2.

The building panel 10 shown in FIG. 2 is similar to that shown in FIG. 1 and only the differences will be described. The same reference numerals will be used for equivalent features. The building panel 10 has a base panel 20 which is made in a similar way to the base panel 20 of the first embodiment, but is thicker. Thus, the base panel 20 as shown in FIG. 1 is made, and then a further grid of steel rods 6 is laid on top of that and two or three further layers of mortar 2 are poured and compressed.

The major surface 9 of the base panel 20 which is nearest to the services distribution trunking 7 is coated with a layer 5 as before. This building panel 10 is intended to form an external wall, although still being non-load- bearing, and so will have a protective layer 1 attached to the other major surface 8 of the base panel 20. A particularly preferred material for the outer layer 1 is lime. A lime layer would be deposited as a slurry, in the same way as the gypsum based layer 5, to a thickness of 16mm. The layer would then be allowed to dry. Lime provides waterproof insulation and furthermore absorbs CO ₂ and so is environmentally beneficial.

Alternatively, shiplap timber cladding 1 can be screwed directly to the base panel 20. In alternative embodiments, wooden battens can be screwed to the base panel 20. Shiplap timber cladding can be nailed to the wooden battens. Equally, ceramic or wooden tiles can be used as the outer

protective layer. Alternatively, bricks can be fixed to the base panel 20 with a layer of cement mortar by the traditional construction method.

Where lime is used as the protective layer 1, the layer, formed from the slurry will naturally have a flat surface 18. However, in another embodiment the lime layer need not have a flat surface. A silicon top mould may be used to shape the surface, for example to a particular texture or pattern.

Equally, the surface of the gypsum based layer 5 can also be moulded and hence need not be flat.

The building panel shown in FIG. 2 can be of a suitable height and width to clad or enclose a building.

The building panel of the first embodiment of the invention as shown in FIG. 3 is similar that shown in FIG. 2 and only the differences from the embodiment of FIG. 2 will be described. The same reference numerals will be used for equivalent features.

Thus, the grids of steel rods 6 are not present in the base panel 20 of the building panel 10 of the first embodiment. Instead, the base panel 20 is thicker and includes a reinforced concrete lattice 4 arranged centrally with respect to the thickness of the panel 20.

To make the reinforced concrete lattice 4, steel rods 26 are positioned within a metal mould (not shown) in the shape of the lattice. Concrete is poured into the mould. When the concrete has been poured, the mould will be mechanically vibrated for three minutes to ensure that the concrete

mixture is homogenous. The concrete will then be left to dry, which might take four days.

The reinforced concrete lattice 4 has a thickness of 70mm and extends over the full width of the base panel 20 so that there are uprights 4a and 4b of the lattice 4 defining either side of the building panel 10. The side surfaces 12 of the building panel 10 are not stepped as they are in the building panels 10 shown in FIG. 1 and FIG. 2. Instead, the lattice upright 4a on one side of the building panel 10 has a rib 30 over its entire height and the upright 4b on the opposite side surface of the building panel 10 has a complementary groove 32 to receive the rib 30 of an adjacent panel 10.

In pouring the mortar 2, a double sided mould is used. Thus, layers of mortar can be poured and compressed as before until half of the base panel 20 has been poured. The mortar 2 is then left to dry for about two days until it is strong enough to be turned over, and the other side of the base panel 20 can then be poured.

The building panel 10 of the first embodiment can be used as a load bearing wall panel because of the reinforced concrete lattice 4 acting as reinforcement for the building panel 10.

Clearly, the outer layer 1 could be replaced with a gypsum based layer 5 as in the building panel shown in FIG. 1 if it were desired to use the building panel 10 as an internal load bearing panel.

The building panel 10 of the second embodiment of the invention as shown in FIG. 4 is similar to the embodiment of

FIG.3 and only the differences will be described. The same reference numerals will be used for equivalent features.

The building panel 10 of FIG. 4 is made in the same way as the building panel of the first embodiment except that, once the core panel 20 has been made as in the first embodiment, further mortar is added. First however a plurality of inflatable devices (not shown) are positioned on top of the mortar 2. Each inflatable device is in the form of an inflated bag of plastics material which may be 300mm by 300mm in plan and about 25mm tall and with compartments within it similar to a bag for making ice cubes. The bags are positioned one beside the other over the surface of the mortar with only a small gap between them. Two layers of mortar 2 are then poured and compressed on top of the bags. Mortar will enter the gaps between the bags. The inflated bags will be lost into the panel but their presence creates insulation cavities 3 within the base panel.

In an alternative preferred embodiment, the cavities are formed from panels of lower density fibre cellulose mortar. For example, if the mortar 2 was 70% paper pulp and lime, the lower density layer could be 90% or 95% paper pulp and lime. The panels are formed and hardened before being introduced into the mould. The mortar 2 is then poured into the mould, so that the base panel forms around the panels. Thus the cavities formed are not empty areas within the building panel as such, but are in fact areas of low-density fibre cellulose mortar .

The building panels of the first and second embodiments will typically be between 2.3m and 2.7m in height. However, panels of at least 10m in height could be produced.

The pulverised glass in the mortar 2 may in an alternative embodiment be replaced by sand or another suitable aggregate material.

A building panel in accordance with a third embodiment of the invention is shown in FIG. 5, FIG. 6 and FIG. 7. The panel comprises an 80mm thick load-bearing layer 100, which is surrounded by a 250mm thick fibre cellulose mortar layer 101. The fibre cellulose mortar 101 comprises embedded electrical conduits 101a.

On a first face of the fibre cellulose mortar layer 101 is a 50mm thick low density fibre cellulose mortar layer 102, which includes a vapour barrier so that it is waterproof. (The vapour barrier is made of recycled plastics material.) On the outer face of the low density waterproof layer 102 is a 40mm thick high density fibre cellulose mortar layer 103, which incorporates an internal metal mesh 103a. This is the external face of the building panel, which is intended to provide an outside surface of a wall of a building.

On the second face of the fibre cellulose mortar layer 101 is a thin layer of gypsum. This is the internal face of the building panel, which is intended to provide an internal surface of a wall of a building.

FIG. 6 shows a number of external finishes that can be added to the building panel, for example a brick tile finish 104, "limecrete" finish 105 (cement mixed with lime), terracotta tile finish 106 (from recycled clay) , or "finish" coat 107 (5mm lime cement rendering felted, 0.5mm grade with a laid-in glass fibre reinforcing mesh) . The brick tile finish 104 is shown in FIG. 7.

The building panels 10 of the present invention have a high R factor in comparison with known materials and are cost competitive with currently available building materials. The building panels 10 are environmentally friendly, in particular by the use of waste material being waste paper or card, waste plasterboard and waste glass. The building panels 10 may be used for a wide range of buildings. They may be used to build houses or for larger buildings for habitation, such as hotels and apartment blocks, or for buildings for storage, such as warehouses.