Construction boards

Abstract

Examples relate to constructions board and methods of manufacturing such construction boards. Examples relate to, for example, methods of manufacturing a construction board. Such methods can comprise: mixing recycling waste from recycling a fibrous material with a calcium sulfate to produce a fibrous mixture comprising: 25% to 50% of recycling waste from recycling a fibrous material; 10% to 40% of calcium sulfate, and 25% to 50% of water; forming the fibrous mixture into a substantially planar form; drying the substantially planar form; and cutting the substantially planar form to produce the construction board.

Description

CONSTRUCTION BOARDS

[0001] The present application generally relates to constructions board and methods of manufacturing constructions board, in particular, to construction boards and methods of manufacturing construction boards from fibrous material.

[0002] According to Eurostat, Packaging Waste by Waste Management Operations, in 2020, 33 million tonnes of paper and cardboard packaging waste was generated in the EU, which represents a substantial increase of more than four million tonnes in just less than a decade. Such a trajectory has the potential to create an additional 40 million tonnes of waste being generated annually by 2030.

[0003] Assuming current rates of paper and cardboard packaging recycling, an estimated 56 million tonnes of paper and cardboard packaging will be disposed of, that is, incinerated or sent to landfill between 2024 and 2030, with an estimated 9 million tonnes being disposed of annually in 2030, which is a missed opportunity.

[0004] Based on Eurostat, Recycling - Secondary Material Price Indicator, the 56 million tonnes waste between 2024 and 2030 has an estimated worth of over€10bn, which is in addition to the costs saved of not sending this waste to landfill; the latter being circa €39 - €46 per tonne in the EU based on the European Environment Agency, Key Strategies to Increase Recycling). Consequently, by 2030, the European paper industry could be wasting 9 million tonnes of waste at a cost of €1.6bn annually.

[0005] While significant investment and efforts have been recognised and realised in the recycling industries, recycling paper and / or cardboard still results in an unusable waste that cannot be used for paper or cardboard recycling due to the fibres being too short.

[0006] Typically, such recycling waste is deposited in landfill and / or incinerated, at very significant cost that also has an adverse environmental impact.

[0007] FIG. 1 shows a view of a first system for manufacturing construction boards;

[0008] FIG. 2 shows a view of a second system for manufacturing construction boards;

[0009] FIG. 3 depicts a view of a manufacturing flowchart for producing construction boards; and

[0010] FIGs. 4A and 4B show a pair of views of construction boards with profiled edges; and

[0011] FIG. 5 illustrates a graph showing sound dampening performance of construction boards.

[0012] Figure 1 shows a view 100 of a system 102 for manufacturing a construction board. The system comprises a mixer 104 for mixing recycling waste from recycling a fibrous material. The recycling waste is stored in a first hopper 106 and fed, under the control of a controller 108 controlling a first hopper valve 110, into the mixer 104. The mixer 104 is arranged to mix the recycling waste with a calcium sulfate. The calcium sulfate is stored in a second hopper 112 and fed, under the control of the controller 108 controlling a second hopper value 114, into the mixer 104. A tank 107.1 containing water is provided to supply water to the mixer 104. Water is supplied to the mixer 104 via a pipe 107.2 in response to operating a valve 107.3 under the controller of the controller 108. The calcium sulfate can comprise calcium sulfate particles, rubble or powder, optionally, a calcium sulfate hemihydrate. The calcium sulfate can comprise gypsum particles, gypsum rubble or gypsum powder. The gypsum particles, rubble or powder can be a recycled gypsum particles, rubble or powder that is obtained from recovered or recycled gypsum boards. Alternatively, or additionally, the gypsum can be synthetic gypsum such as, for example, the gypsum produced during a Flue Gas Desulphurisation process.

[0013] The recycling waste from recycling a fibrous material can comprise at least one, or both, of: paper recycling waste, such as, for example, paper recycling sludge left over from recycling paper and cardboard recycling waste such as, for example, cardboard recycling sludge from recycling cardboard. Hitherto, the recycling waste such as, for example, the sludge, would be diverted to landfill since it is unusable in the paper or cardboard recycling processes. The recycling waste such as, for example, the sludge, can be unsuitable for such reuse in recycling on the basis that the fibres are too short for making recycled paper or recycled cardboard.

[0014] Although examples will be described herein in which the recycling waste is a residual waste left over from recycling, for example, paper or cardboard, examples are not limited to such fibrous materials. Examples can be realised in which the fibrous material can comprise at least one or more of the following taken jointly and severally inany and all permutations: paper fibres, cardboard fibres and a fibrous insulation material. The fibrous material can comprise recycled fibrous insulation material.

[0015] The controller 108 is arranged to monitor and control a set of parameters or conditions associated with the mixture 116 in the mixer 104 via a set of sensors 118. The set of sensors can comprise at least one or more than one of: a speed sensor / controller 120, a temperature sensor / controller 122 and a density sensor 124. Therefore, the controller 108 can, for instance, measure and / or control at least one or more than one of the following parameters taken jointly and severally in any and all permutations: the speed of the mixer 104, the temperature of the mixture 116, and the density of the mixture 116.

[0016] The composition of the fibrous mixture 116 is controlled by the controller to achieve predetermined proportions of the constituents of the fibrous mixture 116. Examples can be realised in which the fibrous mixture 116 comprises 25% to 50%, optionally, 30% to 45%, of recycling waste from recycling a fibrous material, 10% to 40%, optionally, 15% to 35%, of a calcium sulfate and 25% to 50%, optionally, 30% to 50%, of water. It is clear to one skilled in the art that the ranges define a parameter space for the constituents of the fibrous mixture 116 that are balanced to achieve 100% overall.

[0017] When the composition and parameters associated with the mixture 116 meet one or more than one criterion, the mixture 116 is extruded, via an extruder 126, onto a conveyor belt 129. The speed of the conveyor belt 129 is controlled by the controller 108 and an associated conveyor belt speed controller 131.

[0018] The extruder 126 is arranged to form the mixture 116 into a substantially planar form via an appropriately shaped aperture (not shown) that is substantially rectangular. The height of the aperture influences or otherwise controls the thickness of the resulting construction boards. The width of the aperture influences or otherwise controls the width of the construction boards to be a predetermined width. Examples can be realised in which the predetermined width can be set or selected according to required dimensions. Examples can be realised in which the predetermined width can be 600mm or 1200mm. Examples are not limited, however, to being 600mm or 1200mm. Examples can be realised in which the predetermined width is any width specified by a customer.

[0019] The temperature of the mixture 116 is controlled to be within a predetermined temperature range. Examples can be realised in which the predetermined temperaturerange is between 12°C to 40°C, optionally, 35°C. The mixture 116 is maintained within the predetermined temperature range within at least one, or both, of: the mixer 104, and the extruder 126. A hopper (not shown) can also be provided between the mixer 104 and the extruder 126 for storing the mixture 116. The temperature of the mixture 116 within the hopper can also be arranged to be within the predetermined temperature range of 12°C to 40°C, optionally, 35°C.

[0020] Once extruded, the mixture 116 is processed by a compressor 130. The compressor 130 is arranged to compress the substantially planar form of the mixture 116. Examples of the compressor can be realised that use a roller (not shown). The compressor 130 can be arranged to recover water from the compressed mixture 116. The recovered water can be recycled to the water tank 107.3 to control the density or consistency of the mixture during mixing.

[0021] A dryer 134 can be used to at least partially dry the extruded mixture 116. Again, water can be recovered to the water tank 107.3 from the mixture 116 during drying for reuse in establishing the target parameters of the mixture 116 during mixing. The dryer 134 is operable at a predetermined temperature 55°C to 120°C, such as, for example, between 60°C to 90°C. The predetermined temperature is carefully controlled. If the predetermined temperature is too high, the construction board can become sticky and produce an undesirable odour. Conversely, if the predetermined temperature is too low, the construction board can start to delaminate or otherwise lose integrity.

[0022] A water recovery assembly 135 comprising a condenser and associated pipework can be optionally provided to recover water vapour from the dryer. Therefore, examples can be realised in which at least a portion of the 25% to 50% of the water is derived by the water recovery assembly 135 from drying the substantially planar form by the dryer 134. Although not illustrated for clarity purposes, the dryer 148 can also be coupled to the water recovery assembly 135 to recover water from the further drying process. The water recovery assembly 135 can also be coupled to the compressor 130 to recover water from the pressing process, although not shown for clarity purposes.

[0023] A grinder 136 can be provided to grind the upper and lower surfaces of the extruded mixture 116. The upper and lower surfaces of the extruded mixture 116 are ground to set the thickness of the resulting construction board to a predeterminedthickness. Examples can be realised in which the predetermined thickness can be up to 30 mm, optionally between 8 mm and 25 mm, optionally, 22 mm or 10 mm.

[0024] A cutter 138 is arranged to cut the substantially planar form of the mixture 116 into predetermined lengths. Examples can be realised in which the predetermined lengths are between 1500 mm and 3000 mm; optionally, between 2000 mm to 3000 mm, preferably, 2400 mm. Examples can be realised in which the cutter 138 can cut the construction boards into sizes other than the listed sizes indicated. The cutter 138 comprises a cutting mechanism 140 that is controlled by the controller 108 to cut the substantially planar form of the mixture 116 into the predetermined lengths.

[0025] Following cutting, a substrate is applied to at least one side of a cut construction board 141. Optionally, an adhesive dispenser 132 can be arranged to apply an adhesive to the construction board 141 prior to coating with the substrate. Examples can be realised in which the substrate is a paper substrate such as, for example, an uncoated paper. The uncoated paper can have a predetermined weight. Examples can be realised in which the predetermined weight is between 70 grams per square metre and 150 grams per square metre; optionally, 80 grams per square metre to 110 grams per square metre.

[0026] Once cut and coated with the substrate, the construction boards 142 to 146 are further dried in a dryer 148. In the example depicted, several cut construction boards 150 and 154 are shown as being dried. Again, water recovered during the drying process can be recovered and recycled for producing the mixture 116.

[0027] Following drying in the oven 148, the dried boards are stacked on a stacker 156 and can be wrapped in a protective waterproof film (not shown). Several dried construction boards 158 to 162 are shown in figure 1.

[0028] Figure 2 shows a view 200 of a second system 202 for manufacturing a construction board. The sole difference between the first system 102 and the second system 202 is the provision of an additional substrate or coating 204 that is deposited onto the cut construction board 141 . Therefore, examples can be realised in which the resulting construction board 141 is coated with a substrate on both sides of the board. Optionally, an adhesive dispenser 132’ can be arranged to apply an adhesive to the construction board 141 prior to coating with the additional substrate. Examples can be realised in which the additional substrate is a paper substrate such as, for example, an uncoated paper.The uncoated paper can have a predetermined weight. Examples can be realised in which the predetermined weight is between 70 grams per square metre and 150 grams per square metre; optionally, 80 grams per square metre to 110 grams per square metre.

[0029] The adhesive dispenser 132 and an associated roller (not shown) bearing the substrate 128, or the adhesive dispensers 132, 132’ and respective rollers (not shown) bearing the substrates 128 and 204 are examples of a substrate assembly or substrate assemblies respectively.

[0030] Figure 3 depicts a view 300 of a flowchart 302 for manufacturing a construction board.

[0031] At 304, the controller 108 actuates the value 110 of the recycling waste hopper 106 to deposit recycling waste into the mixer 104.

[0032] The controller 108 acquires data relating to the condition of the mixture 116 in the mixer 104 from the set of sensors 118 at 306.

[0033] A determination is made, at 308, regarding whether or not the mixture 116 is acceptable. The determination can comprise assessing the density of the mixture 116. Examples can be realised in which the mixture has a density of greater than a predetermined lower bound and lower than or equal to a predetermined upper bound. Examples can be realised in which fibrous mixture has a density greater than O.Sg / cm3and less than 1.4^ / cm3; optionally, greater than Ig / cm3and less than 1.25^ / cm3.

[0034] If the determination at 308 is negative, the controller 108 is arranged, at 310, vary the composition of the mixture. The controller 108 varies the composition of the mixture 116 by adding at least one or more than one of the following taken jointly and severally in any and all permutations: the recycling waste, calcium sulfate and water. The additions are effected by actuating respective valves of the above described valves 110, 114 and 107.3 to influence the composition of the mixture 116.

[0035] The mixture 116 is consistently agitated at 312, and the controller 108 returns to 308 to assess the composition of the mixture. During agitation, the controller 108 is arranged to monitor and influence a set of characteristics of the mixture 116. The set of characteristics comprises one or more than one characteristic. The set of characteristics can comprise at least one or more than one of the following taken jointly and several inany and all permutations: the relative proportions of calcium sulfate, water and recycling waste, the temperature of the mixture 116, the density of the mixture 116 and the viscosity of the mixture 116. Examples can be realised in which the characteristics of the mixture 116 have a predetermined range, amount or ratio of recycling waste from recycling a fibrous material, a predetermined range, amount or ratio of calcium sulfate and a predetermined range, amount or ratio of water. Examples can be realised in which the set of characteristics comprise one or more than one of the following taken jointly and severally in any and all permutations: the percentage of calcium sulfate in the mixture 116 is between 10% to 40%, optionally, 15% to 25%, the percentage of a fibrous material is between 25% and 50%, optionally, 30% to 45%, and the percentage of water is between 25% and 50%, optionally, 30% to 45%.

[0036] If the determination at 308 is that the composition of the mixture 116 is acceptable, the fibrous mixture is extruded, at 314.

[0037] Following extrusion, the extruded fibrous mixture 116 is compressed, at 316, using the above-described compressor 130. During compression, any water removed from the fibrous mixture 116 is recovered to the tank 107.3 for recycling into the mixture 116 within the mixer.

[0038] The fibrous mixture 116 is dried in the first drier or oven 134 at 318. Additionally, water can be recovered from the dryer 134 by the water recovery assembly 135.

[0039] The substantially planar mixture 116 is subjected to a further process, at 320, to achieve a precise predetermined thickness. The further process can comprise grinding using the above-described grinder 136. The precise predetermined thickness can be up to 30 mm, optionally between 8 mm and 25 mm, optionally, 22 mm or 10 mm.

[0040] At 322, the substantially planar fibrous mixture 116 is cut into one or more than one predetermined length using the above-described cutter 138 and cutting mechanism 140 to create construction boards of the one or more than one predetermined length.

[0041] At 324, the cut construction board 141 is coated with the above-described substrate on one side in the case of a single substrate construction board shown in, and described with reference to figure 1 , or on both sides in the case of a dual substrate construction board shown in, and described with reference to, figure 2.

[0042] Following coating with the substrate or substrates, the construction boards are cured or further dried at 326. Additionally, water can be recovered from the dryer 148 by the water recovery assembly 135.

[0043] The cured construction boards can be at least one, or both, of: stacked on the stacker and wrapped in a water-proof covering at 328.

[0044] Referring to figures 4A and 4B, there is shown a pair of views 400 of construction boards 402 fabricated using methods as described and / or claimed herein.

[0045] The construction boards 402 comprise at least one profiled edge 404. Examples can be realised in which the profiled edge takes the form of a narrowing. Such a narrowing can be realised as a transitional region 406 that transitions from the full construction board thickness to a narrower board thickness region 408 as shown in figure 4A. The narrower board thickness region 408, in the example shown, is parallel to the main upper planar surface 410. The profiled edge is formed during a grinding process performed by, for example, the above described grinder 136 or a further grinder (not shown in either of figures 1 and 2). The profiled edge provides a region for receiving a coating such as, for example, plaster, to cover the edges of adjacent boards. Examples can be realised in which the profiled edge 404 runs the whole length of an edge. Examples can be realised in which the profiled edge 404 spans at least one selectable portion of the whole length of the edge.

[0046] Examples can be realised in which the construction boards 402 comprise a number of profiled edges. Examples can be realised in which construction boards comprises at least two profiled edges. The at least two profiled edges can be disposed on opposite edges of the construction board. The opposite edges can be at least a pair of longer edges of the construction board. The opposite edges can be at least a pair of shorter edges. Examples can be realised in which all edges of the constructions boards 402 are profiled.

[0047] Referring to figure 4B, there is shown an example of such a construction board 402 having profiled edges together with having the substrate 412 deposited on both sides of the construction board 402.

[0048] Figure 5 shows a view 500 of a graph 502 of performance data for a construction board. The graph 502 shows a variation in sound proofing or sound dampening with frequency. The thick solid line 504 shows the performance of construction boards according to examples and the thin solid line 506 shows the performance of typical gypsum construction boards. For example, at a frequency of 4800 Hz, the sound dampening for example construction boards is 34 dB, which compares very favourably with typical gypsum board that has a corresponding dampening of only 28 dB.

[0049] Although the above examples have been described in which the paper substrate is applied after cutting, examples are not limited to such arrangements. Examples can be realised in which the substrate or substrates could be applied before cutting. For instance, examples can be realised in which the substrate or substrates can be applied after grinding. Examples can be realised in which at least one substrate, such as, for instance, the lower substrate, is deposited before grinding and / or before drying.

[0050] Although the above examples have been described with reference to the substrate being deposited onto a cut construction board, examples are not limited to such an arrangement. Examples can be realised in which the fibrous mixture 116 is deposited onto the substrate 128. Therefore, examples can be realised in which depositing the fibrous mixture 116 onto the substrate 128 can comprise extruding the fibrous mixture 116 onto the substrate 128. Extruding the fibrous mixture 116 onto the substrate 128 can use the above-described extruder 126, which results in a substantially planar form of the mixture 116.

[0051] The resulting construction boards are designed to comply with European classification no. ETA 06 / 0104, which covers certification in respect of a set of characteristics. The set of characteristics comprises at least one or more than one of the following taken jointly and severally in any and all permutations: fire resistance, biological properties, physical properties, moisture tolerance, and production process documentation. For instance, examples can be realised in which the fire classification is Reaction to fire: A2-s1 ,d0, fire protective class: K10, fire resistance classification: EI60.

[0052] Construction boards according to present examples have one or more than one of the characteristics in the table below taken jointly and severally in any and all permutations:

Claims

CLAIMS1 . A method of manufacturing a construction board, the method comprising a. mixing a fibrous material with a calcium sulfate to produce a fibrous mixture comprising i. 25% to 50% of a fibrous material; ii. 10% to 40% of calcium sulfate iii. 25% to 50% of water b. forming the fibrous mixture into a substantially planar form; c. drying the substantially planar form; and d. cutting the substantially planar form to produce the construction board.

2. The method of claim 1 in which the fibrous material comprises fibrous insulation material or recycling waste from recycling a fibrous material; optionally, the recycling waste from recycling a fibrous material comprises a post-material recycling waste.

3. The method of claim 2, in which the recycling waste from recycling a fibrous material comprises a post-paper recycling waste or a post-cardboard recycling waste.

4. The method of any preceding claim, in which said fibrous mixture has a density greater than O.Sg / cm3and less than 1.4^ / cm3; optionally, greater than Ig / cm3and less than 1.25g / cm3.

5. The method of any preceding claim, in which the calcium sulfate comprises a calcium sulfate particles, rubble or powder; optionally, a calcium sulfate hemihydrate, preferably, a calcined gypsum powder.

6. The method of any preceding claim, comprising maintaining the temperature of the mixture within a predetermined temperature range, optionally, within a predetermined temperature range of 12°C to 40°C, optionally 35°C.

7. The method of any preceding claim, in which forming the fibrous mixture into a substantially planar form comprises at least one, or both, of: a. extruding the fibrous mixture into the substantially planar form, or b. pressing the fibrous mixture into the substantially planar form.

8. The method of any preceding claim in which forming the fibrous mixture into a substantially planar form comprises forming the fibrous mixture into a substantially planar form having a predetermined extruded thickness.

9. The method of any preceding claim in which forming the fibrous mixture into a substantially planar form comprises forming the fibrous mixture into a substantially planar form having a predetermined width.

10. The method of any preceding claim, in which cutting the substantially planar form to produce the construction board comprises edge trimming to condition the construction board for use.

11. The method of any preceding claim, in which drying the substantially planar form uses a predetermined temperature of between 55°C to 120°C, optionally 60°C to 90°C.

12. The method of any preceding claim, comprising deriving at least a portion of the 25% to 50% of the water from said drying the substantially planar form.

13. The method of any preceding claim, further comprising grinding the substantially planar form to the predetermined thickness.

14. The method of any preceding claim, comprising forming at least one profiled edge or a plurality of profiled edges.

15. The method of any preceding claim in which cutting the substantially planar form to produce the construction board comprising cutting the substantially planar formto have a predetermined length.

16. The method of claim 15, in which cutting the substantially planar form to have a predetermined length comprises cutting the substantially planar form to have dimensions of a predetermined length of between 1500 mm and 3000 mm; optionally, between 2000 mm to 3000 mm, preferably, 2400 mm.

17. The method of any preceding claim, comprising applying a substrate to at least one side of the substantially planar form.

18. The method of claim 17, comprising applying the substrate to two sides of the substantially planar form.

19. The method of any preceding claim, in which forming the fibrous mixture into a substantially planar form comprises depositing the fibrous mixture onto a substrate; the substrate forming part of the construction board; preferably, the substrate is a paper substrate.

20. The method of any of claims 17 to 19, in which the substrate is a paper substrate is suitable for painting.

21. The method of claim 20, in which the paper substrate is an uncoated paper substrate.

22. The method of either of claims 20 and 21 , in which the paper substrate has a predetermined weight of between 70 grams per square metre and 150 grams per square metre; optionally, 80 grams per square metre to 110 grams per square metre.

23. A system to manufacture a construction board, the system comprising: a. a mixer to mix a fibrous material with a calcium sulfate to produce a fibrous mixture comprising: i. 25% to 50% of a fibrous material; ii. 10% to 40% of calcium sulfate iii. 25% to 50% of water b. an extruder to form the fibrous mixture into a substantially planar form; c. at least one dryer to dry the substantially planar form; and d. a cutter to cut the substantially planar form to produce the construction board.

24. The system of claim 23 in which the fibrous material comprises fibrous insulation material, recycling waste from recycling a fibrous material; optionally, the recycling waste from recycling a fibrous material comprises a post-material recycling waste.

25. The system of claim 24, in which the recycling waste from recycling a fibrous material comprises a post-paper recycling waste or a post-cardboard recycling waste.

26. The system of any of claims 23 to 25, in which said fibrous mixture has a density greater than O.Sg / cm3and less than 1.4^ / cm3; optionally, greater than Ig / cm3and less than 1.25^ / cm3.

27. The system of any of claims 23 to 26, in which the calcium sulfate comprises a calcium sulfate particles, rubble or powder; optionally, a calcium sulfate hemihydrate, preferably, a calcined gypsum powder.

28. The method of any preceding claim, comprising maintaining the temperature of the mixture within a predetermined temperature range, optionally, within a predetermined temperature range of 12°C to 40°C, optionally 35°C.

29. The system of any of claims 23 to 28, in which the extruder is arranged to form the fibrous mixture into a substantially planar form by at least one, or both, of: e. extruding the fibrous mixture into the substantially planar form, or f. pressing the fibrous mixture into the substantially planar form.

30. The system of any of claims 23 to 29, in which the extruder is arranged to form the fibrous mixture into a substantially planar form having a predetermined extruded thickness.

31. The system of any of claims 23 to 30, in which the extruder is arranged to form the fibrous mixture into a substantially planar form having a predetermined width.

32. The system of any of claims 23 to 31 , in which the cutter to cut the substantially planar form to produce the construction board is arranged to trim the edges of the construction board.

33. The system of any of claims 23 to 32, in which the dryer to dry the substantially planar form uses a predetermined temperature of between 55°C to 120°C, optionally 60°C to 90°C.

34. The system of any of claims 23 to 32, comprising a water recovery assembly to derive at least a portion of the 25% to 50% of the water from said drying the substantially planar form.

35. The system of any of claims 23 to 34, further comprising a grinder to at least one, or both, of: grind the substantially planar form to the predetermined thickness, and form at least one profiled edge or a plurality of profiled edges.

36. The system of any of claims 23 to 35, in which the cutter to cut the substantially planar form to produce the construction board is arranged to cut the substantially planar form to have a predetermined length.

37. The system of claim 36, in which the cutter to cut the substantially planar form to have a predetermined length is arranged to cut the substantially planar form to have dimensions of a predetermined length of between 1500 mm and 3000 mm; optionally, between 2000 mm to 3000 mm, preferably, 2400 mm.

38. The system of any claims 23 to 37, comprising a substrate assembly to apply a substrate to at least one side of the substantially planar form.

39. The system of claim 38, comprising in which the substrate assembly is arranged to apply the substrate to two sides of the substantially planar form.

40. The system of either of claims 38 and 39, in which the extruder is arranged to deposit the fibrous mixture onto the substrate; the substrate forming part of the construction board.

41. The system of any of claims 38 to 40, in which the substrate is a paper substrate is suitable for painting.

42. The system of any of claims 38 to 41 , in which the paper substrate is an uncoated paper substrate.

43. The system of either of claims 38 and 42, in which the paper substrate has a predetermined weight of between 70 grams per square metre and 150 grams per square metre; optionally, 80 grams per square metre to 110 grams per square metre.

44. A construction board manufactured according to a method of any of claims 1 to 22.