Aluminium sheets as combined formwork and reinforcement of concrete structures
The use of aluminium alloy plates and distance bars as formwork and reinforcement in concrete elements addresses the environmental and structural challenges of traditional concrete, achieving reduced emissions, simplified construction, and lighter structures.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-09-05
- Publication Date
- 2026-03-19
AI Technical Summary
The concrete industry contributes significantly to CO2 emissions due to the production of Portland cement, and steel-reinforced concrete structures face issues with corrosion and require thick concrete covers for protection, increasing weight and complexity.
A loadbearing plate system using aluminium alloy metal plates and distance bars, which serve as both formwork and reinforcement, filled with low CO2 calcinated clay concrete, eliminating the need for separate formwork and reducing the thickness of concrete sections.
This system reduces the carbon footprint, simplifies construction, and decreases the weight and load of concrete structures by eliminating the need for a protective concrete cover, making them lighter and more efficient for various applications.
Smart Images
Figure EP2025075312_19032026_PF_FP_ABST
Abstract
Description
[0001] TITLE: ALUMINIUM SHEETS AS COMBINED FORMWORK AND REINFORCEMENT OF CONCRETE STRUCTURES
[0002] TECHNICAL FIELD
[0003] The present invention relates to a loadbearing plate system and a reinforced concrete element. The present invention also relates to a method of fabricating a reinforced concrete element.
[0004] BACKGROUND
[0005] Concrete production worldwide is major emitter of CO2 with a significant carbon footprint. The travel and aircraft industry produces 2% of the annual CO2 emissions in the world while the concrete industry produces 5-8%.
[0006] Concrete is composed mainly of (Portland) cement and aggregates, among others. The main source of CO2 emission is the production of Portland cement. The raw material for the Portland cement is made by heating, in a cement kiln to a calcining temperature of above 600°C and then a fusion temperature, which is about l,450°C.
[0007] The Romans used shape to design concrete structures without reinforcement. The tensile strength of concrete is low, maybe a tenth of the compressive strength. This is why the Romans shaped their structures, so they did not experience tension, by for example providing semicircular supports of bridges. They did not have steel reinforcement. Many of the structures still exist today, some of them are still in use.
[0008] A couple of hundred years ago, steel reinforcement was introduced to concrete design. As a result, structures became more slender and lighter. However, they had or have a limited lifetime as the steel reinforcement corrodes with time due to ingress of water and chlorides from e.g. seawater or car traffic.
[0009] Modem steel reinforced concrete is protected against corrosion by the high alkalinity of the concrete. Fresh concrete has a pH of around 12.5 to 13.5. This forms a thin and stable oxide layer on the steel surface, also known as the passivation layer. In addition, the steel is protected by a concrete layer formed over the steel reinforcements, called the “cover”. Increased corrosion protection is achieved by increasing the cover thickness. It also increases the weight of the concrete structure due to the increase in wall thickness.
[0010] Aluminium is protected by a natural oxide layer against corrosion from e.g. seawater. However, alkaline environments exceeding a pH of about 9, such as the one found in traditional concrete will attack the oxide layer and will make aluminium vulnerable again.
[0011] Recent research in Norway has demonstrated that it is possible to replace large portions of the cement with calcinated clay and reduce the pH value of the resulting concrete material to less than 9. Calcinated clay requires a temperature of 850 degrees Celsius for the calcination process. Thus, resulting in reduced need for energy and CO2 emission.
[0012] It is an aim of the present disclosure to provide reinforced concrete elements and structures with significantly reduced carbon footprint compared to prior art precast or cast in-situ reinforced concrete elements.
[0013] A further aim is to reduce the thickness of the section of the reinforced concrete elements, as cover is no longer required.
[0014] A further aim of the invention is to simplify the building process by providing both shutters for casting the concrete and at the same time reinforcement for the concrete element.
[0015] SUMMARY OF THE INVENTION
[0016] The present invention is directed to a solution that may solve or at least reduce at least one of the aforementioned problems or challenges.
[0017] The invention is defined in the attached claims.
[0018] It is described a reinforced concrete element comprising a loadbearing plate system, comprising:
[0019] - two aluminium alloy metal plates, wherein each of the metal plates has an outer plate surface and an inner plate surface;
[0020] - a plurality of distance bars; wherein the distance bars extend between the respective inner plate surfaces over a distance, wherein the inner plate surfaces face each other and form an inner volume therebetween, wherein the loadbearing plate system comprises shutters between the metal plates to enclose the inner volume, wherein the inner volume is filled with pourable concrete, wherein the pourable concrete is a calcinated clay pourable concrete.
[0021] The inner volume may be configured to receive pourable concrete.
[0022] The distance bars may be made of aluminium alloy. The distance bars may be joined at a first bar end to one of the inner plate surfaces and at a second bar end to the other inner plate surface.
[0023] The distance bars may be joined by welding or bolting to the inner plate surface.
[0024] Alternatively, the distance bars may be joined by drilling a hole in the metal plate and bolting the distance bar to the metal plate.
[0025] The plate distance may be constant.
[0026] The metal plates may be identical.
[0027] Alternatively, the plate distance may be variable.
[0028] The metal plates may be parallel.
[0029] The height and / or width of the metal plates may be extended by joining a further metal plate at a joint to the respective metal plates.
[0030] A suitable joining method for the metal plates may be welding and or mechanically fastening.
[0031] The inner plate surfaces may be mechanically treated to create a pattern on the inner plate surfaces.
[0032] The inner plate surface may have a checkered pattern.
[0033] The loadbearing plate system may be used as a casting mould for the reinforced concrete element.
[0034] The distance bars may be used to stabilize the loadbearing plate system during pouring of the pourable concrete and act as reinforcements for the reinforced concrete element.
[0035] The pourable concrete may be a so-called low CO2 carbon footprint calcinated clay pourable concrete.
[0036] The metal plates may be parallel with the x- and y direction of a Cartesian coordinate system.
[0037] The reinforced concrete element may be a wall element.
[0038] The metal plates may be parallel with the x- and z direction of a Cartesian coordinate system.
[0039] The reinforced concrete element may be a floor element.
[0040] It is further described a method of fabricating a reinforced concrete element as described above, wherein the method may comprise: - positioning the metal plates to form a loadbearing plate system;
[0041] - connecting the distance bars at a first bar end to one of the inner plate surfaces and at a second bar end to the other inner plate surface,;
[0042] - providing pourable concrete into the inner volume.
[0043] The method may further comprise mechanically treating the inner surfaces of the metal plates.
[0044] The method may further comprise extending a height and / or width of the metal plates by joining a further metal plate at a joint to the respective metal plates to form a loadbearing plate system.
[0045] The loadbearing plate system may have one or more of the following advantages:
[0046] - it serves as shutter during casting of the concrete and afterwards serves as reinforcement of the concrete element thus saving time as shutters do not need to be removed before using the concrete element;
[0047] - the use of aluminium metal plates and bars permits the use of calcinated clay with significantly reduced CO2 footprint, and
[0048] - as aluminium is used, the thickness (and weight) of the concrete can be reduced as the aluminium does not need to be protected against rust by the concrete cover,
[0049] - the reduced weight also means reduced loads. This is important for concrete structures, for foundations, loadbearing elements, and particularly for structures that float.
[0050] DESCRIPTION OF THE DRAWINGS
[0051] Following drawings are appended to facilitate the understanding of the claimed invention:
[0052] Fig. 1 - illustrates a perspective view of the loadbearing plate system;
[0053] Fig. 2 - illustrates a perspective view of the loadbearing plate system with curved metal plates;
[0054] Fig. 3 - illustrates a perspective view of the inside of the loadbearing plate system;
[0055] Fig. 4a - illustrates a perspective view of the loadbearing plate system which has been extended with further metal plates;
[0056] Fig. 4b to 4e - illustrates a cross-sectional view of joints between metal plates;
[0057] Fig. 5 - illustrates a perspective view of the loadbearing plate system with the shutters in place;
[0058] Fig. 6 - illustrates a perspective view of a reinforced concrete element used as a wall element; Fig. 7 - illustrates a perspective view of a reinforced concrete element used as a floor element.
[0059] DETAILED DESCRIPTION
[0060] In the following, one or more specific embodiments of the invention will be described in more detail with reference to the drawings. However, it is specifically intended that the invention is not limited to the embodiments and illustrations contained herein but includes modified forms of the embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation- specific decisions must be made to achieve the developer’s specific goals, such as compliance with system and / or business -related constraints, which may vary from one implementation of the invention to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication and manufacture for the skilled person having the benefit of this disclosure.
[0061] A loadbearing plate system 10
[0062] Figure 1 discloses a loadbearing plate system 10 comprising two metal plates 12 and several distance bars 15. Each of the metal plates 12 has an outer plate surface So and an inner plate surface Si. The distance bars 15 extend between the respective inner plate surfaces Si over a distance D. The distance D is measured normal to the inner plate surfaces Si. The distance D between metal plates 12 is constant when the metal plates 12 are parallel. However, the distance D may be variable and change across the metal plates 12 resulting in a conical or wedge-shaped load bearing plate systems 10. Metal plate 12 is arranged in the x-y plane of the co-ordinate system, while distance D is usually measured in the z-direction of the co-ordinate system, see also figure 1
[0063] As shown in figure 1, the inner plate surfaces Si of the two metal plates 12 face each other and form an inner volume Vol between themselves. The inner volume Vol will be filled later with pourable concrete 25. The plates 12 may be made of aluminium alloy. Furthermore, the distance bars 15 may also be made of aluminium alloy.
[0064] The metal plates 12 may be curved. As shown in figure 2, the two metal plates may have a first plate radius R1 and a second plate radius R2. Shown in fig. 3, the distance bars 15 have a first bar end 15fe and a second bar end 15se. The distance bars 15 are joined at a first bar end 15fe to one of the inner plate surfaces Si and at a second bar end 15se to the other inner plate surface Si.
[0065] There are several possibilities to join the distance bars 15 to the inner plate surface Si, including welding or bolting. These processes can also be combined. Important considerations are that the equipment used is portable as in most cases the joining operation will be done at the building site. When the distance bars 15 are bolted, holes may be drilled through the metal plate 12 to lock the bolt from both sides of the metal plate 12 or from the outside of the metal plate 12.
[0066] The size of the metal plate 12 is limited by practical consideration, such as being able to transport metal plates 12 on lorries to the building site. If larger metal plates 12 are needed, the metal plate 12 may be extended by joining a further metal plate 12 at a joint 17 to the respective metal plates 12 as shown in figure 4a. Metal plates 12 may be joined by butt or fillet welding (see figure 4b) or mechanically fastened by for example bolts using profiles 18 to align and hold the plate edges in place as shown in figure 4c or a one-sided profile 18 as shown in figure 4d. They may be welded in addition. A further option is to use one or two external strips, overlapping the plate joint (figure 4e). These strips may be bolted or welded to the two metal plates 12 to ensure load transfer.
[0067] A concrete element 20
[0068] Figure 5 shows the load bearing plate system 10 with additional shutters 23 in place. When the load bearing plate system is placed on a base B, the shutters 23 close all remaining openings, except for the top surface, thus providing a liquid tight barrier. The base B may be for example a foundation or the ceiling of the floor below or a wall element of the floor below. The inner volume Vol is enclosed by the base B, the metal plates 12 and the shutters 23, thus becoming a casting mould for concrete.
[0069] When designing the concrete element 20, the material properties of the concrete, metal plates 12 and distance bars 15 must be known. Appropriate software exists for this type of calculations. Additionally, as the metal plates 12 act as reinforcement, the joints between the metal plates 12 need to be designed.
[0070] As mentioned earlier, traditional concrete structures reinforced with steel bars require a concrete cover to protect the bars from rusting. This is not required when using aluminium plates as aluminium does not rust. This means that the concrete element 20 has little or no concrete cover, making it much lighter than a traditional concrete section. The reduced weight, results also in reduced loads for example on foundations, loadbearing elements, and particularly for structures that float. To produce a concrete element 20, concrete 25 is poured into the inner volume Vol of the loadbearing plate system 10. The distance bars 15 keep the metal plates 12 at the predetermined distance D and stabilizing the concrete element 20 while the concrete 25 sets. Once the concrete 25 has hardened, the loadbearing plate system 10 acts as reinforcements for the reinforced concrete element (20).
[0071] The pourable concrete 25 may be a so-called low CO2 carbon footprint calcinated clay pourable concrete 25.
[0072] The inner plate surface Si of the metal plate 12 may be mechanically treated or modified to achieve better adhesion of the concrete to the inner plate surface Si. Alternatively, the metal plate 12 may be supplied with surface deformations like the ones known from floor plates, so called anti-slip surfaces as shown in figure 3. The patterns on the inner plate surface Si are similar to patterns known from traditional steel reinforcing bars. These patterns avoid slipping of the concrete and increase its adhesion to the surface. The inner plate surface may have a checkered pattern, evenly dispersed over the inner plate surface Si.
[0073] The reinforced concrete element 20 may be used for different applications. When the metal plates 12 are parallel with the x- and y direction of a Cartesian coordinate system, the reinforced concrete element 20 may be a wall element, see figure 6. When the metal plates 12 are parallel with the x- and z-direction of a Cartesian coordinate system, the reinforced concrete element 20 may be a floor element as shown in figure 7. For floor elements, ventilation holes may be provided in the top metal plates 12.
[0074] Fabricating the concrete element 20
[0075] The method of fabricating the reinforced concrete element 20 comprises positioning the metal plates 12 to form a loadbearing plate system 10. Distance bars 15 are connected at a first bar end 15fe to one of the inner plate surfaces Si and at a second bar end 15se to the other inner plate surface Si, wherein the distance bars 15 and providing pourable concrete 25 into the inner volume Vol.
[0076] The method is typically carried out at the building site. The components, namely metal plates 12 and distance bars 15 can easily be transported to any location. Portable drills or welding machines are required to attach the distance bars 15 to the metal plates 12. Moreover, a (small) crane is needed to erect the metal plates 12. Because of its simplicity, the method is suitable for many different projects ranging from simple DIY projects to complex civil engineering projects.
[0077] A further aspect of the method is that metal plates 12 are used, with mechanically treating the inner surfaces Si of the metal plates 12. This will enhance the adhesion of the concrete to the inner surface SI and improve transfer of shear loads between the concrete and the inner surface Si of the metal plates 12.
[0078] The method also may comprise the step of extending a height h and / or width w of the metal plates 12 by joining a further metal plate 12 at a joint 17 to the respective metal plates 12.
[0079] Using the concrete element 20
[0080] Concrete structures come in many types, and it is not possible to find one general accurate effect of using aluminum reinforced concrete. Concrete is heavy, with a unit weight of 2.5t / m3, aluminum about the same, and steel 7.85t / m3. For comparison the unit weight of a car may be 0.25t / m3. But the effect of the weight on the structure depends on the structure. For a long span bridge, the effect is large while for a vertical cylinder standing on a rock foundation, it is small. For the vertical cylinder, most of the material saving is related to not needing the cover for aluminum reinforcement.
[0081] However, for a vertical cylinder with a foundation floating in water, such as a floating wind turbine, the weights saving effect of using the concrete element 20 is large. If in sea water, the required concrete cover for corrosion protection may be 60 or 70mm for ordinary steel reinforcement, on both sides if there is water inside also. The weight of the complete concrete structure must be carried by the buoyancy of the floating foundation.
[0082] Parametric design work on floating cylinders shows that cylinders with moderately stressed walls are more expensive than cylinders with highly stressed walls. Simply because moderately stressed walls are heavier than the highly stressed ones.
[0083] In the preceding description, various aspects of the apparatus and method according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the apparatus and its workings. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the apparatus and method, which are apparent to person skilled in the art to which the disclosed subject-matter pertains, are deemed to lie within the scope of the present invention as defined by the following claims. LIST OF REFERENCE NUMBERS
[0084] 10 - loadbearing plate system 12 - metal plate
[0085] 15 - distance bar
[0086] 15fe - first bar end
[0087] 15se - second bar end
[0088] 17 -joint
[0089] 18 - profile for joints
[0090] 20 - reinforced concrete element
[0091] 23 - shutters
[0092] 25 - pourable concrete
[0093] B - base
[0094] D - plate distance between metal plates w - width of the metal plates h - height of the metal plates P - perimeter of the metal plates R1 - first plate radius of the metal plates R2 - second plate radius of the metal plates Si - inner plate surface So - outer plate surface Vol - inner volume
Claims
CLAIMS1. A reinforced concrete element (20) comprising a loadbearing plate system (10), comprising:- two aluminium alloy metal plates (12), wherein each of the metal plates (12) has an outer plate surface (So) and an inner plate surface (Si);- a plurality of distance bars (15); wherein the distance bars (15) extend between the respective inner plate surfaces(Si) over a distance (D), wherein the inner plate surfaces (Si) face each other and form an inner volume (Vol) therebetween, wherein the loadbearing plate system (10) comprises shutters between the metal plates (12) to enclose the inner volume (Vol), wherein the inner volume (Vol) is filled with pourable concrete (25), wherein the pourable concrete (25) is a calcinated clay pourable concrete (25).
2. The reinforced concrete element (20) according to claim 1, wherein the distance bars (15) are joined at a first bar end (15fe) to one of the inner plate surfaces (Si) and at a second bar end (15se) to the other inner plate surface (Si).
3. The reinforced concrete element (20) according to any one of the preceding claims, wherein the plate distance (D) is constant.
4. The reinforced concrete element (20) according to any one of the preceding claims, wherein the metal plates (12) are parallel.
5. The reinforced concrete element (20) according to any one of the preceding claims, wherein the height (h) and / or width (w) of the metal plates (12) is extended by joining a further metal plate (12) at a joint (17) to the respective metal plates (12).
6. The reinforced concrete element (20) according to any one of the preceding claims, wherein the inner plate surfaces (Si) are mechanically treated to create a pattern on the inner plate surfaces (Si).
7. The reinforced concrete element (20) according to any one of the preceding claims, wherein the metal plates (12) are parallel with the x- and y direction of a Cartesian coordinate system.
8. The reinforced concrete element (20) according to any one of the preceding claims, wherein the metal plates (12) are parallel with the x- and z direction of a Cartesian coordinate system.
9. A method of fabricating a reinforced concrete element (20) according to any one of the preceding claims, wherein the method comprises:- positioning the metal plates (12) to form a loadbearing plate system (10);- connecting the distance bars (15) at a first bar end (15fe) to one of the inner plate surfaces (Si) and at a second bar end (15se) to the other inner plate surface (Si);- providing pourable concrete (25) into the inner volume (Vol).
10. The method according to claim 9, wherein the method further comprises:- mechanically treating the inner surfaces (Si) of the metal plates (12).
11. The method according to claim 9 or 10, wherein the method further comprises:- extending a height (h) and / or width (w) of the metal plates (12) by joining a further metal plate (12) at ajoint (17) to the respective metal plates (12) to form a loadbearing plate system (10).
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