Technical field The present invention concerns building elements and a method of construction using the building elements.

Background

Concrete is the most important building material in the wo rid. Buildings built out of concrete require a very strong supporting construction; there only for the sake of being able to carry the concrete's own heavy weight It has been calculated thatabout80% of the structural design of a traditional concrete building serves to carry its own weight Despite its many times disproportional weight, Ihe material has itself several important and good properties, Fbr example, it is durable, strong, non-combustible and easily to shape by casting. Cement, which is the main raw material is very energy consuming at its manufacture and releases a very large amountof CO ₂ into the atmosphere. Therefore, there is an important reason to use a concrete building engineering which takes the positive properties of the material as a starting point and minimize the negative by being able to reduce the volumetric weight by about 80%.

The house building offers many engineered constructional solutions which use a number of different materials with different functions in the completed construction. The insulating function often causes heavy problems since these materials in price worthy applications either are tight and inflammable (for example expanded polystyrene) or non-combustible but open (mineral wool). The inflammable insulating materials are problematic already due to the inflammability, but involves also by means of its tightness a risk of moisture enclosure if the construction is notthoroughly designed and executed. The open insulating materials also require cost increasing constructions for mounting and moisture protection and are practically incompatible with a stone house. Generally, the building methods of today are based on a multi material technology where different types of materials are used in collaboration and are expected to solve different functions when they are mounted together. This increases the demands on the engineer since it concerns complicated relationships which are difficult to calculate. At the same time, it is expected from the building industry to develop both more cost effective methods as well as energy saving material and constructions.

The reasons for many building problems are often the result of unsuitable material combinations which cause the final constructed structure to not function in the proper way together. Additionally, a non-industrial working method with long production time at the building site causes a risk for the building materials to be exposed to rain and chill during the long mounting time. The costs for heating and cooling, respectively, of the indoor air increases dramatically today at the same time as the society wishes to decrease unnecessary energy due to environmental considerations. It is therefore of utmost importance to provide a both effective and fireproof insulation that does not risk the build up of moisture and mould establish in the construction, but instead allows the walls of the building to breath. The modem air-tight houses, with the aim of providing an effective insulation in order to save energy, has instead caused the build up of moisture in the construction. This problem has created not only an economic problem for the builder, but has also led to public health concerns.

Building blocks of lightweight concrete having a volumetric weight between 400 - 800 kg/ m ³ have been produced since 1930. The first lightweight concrete was based on alum slate. However, in the 1970s the inexpediency to use this material was called attention to since it comprises uranium which emits radon, which led to a stop in production of lightweight concrete based on alum slate in 1975. After that lightweight concrete has subsequently been produced outof, for example, finely ground sandstone, cement and lime, which are forced to expand in an autoclave by means of a gas development caused by the heating of aluminium powder in the formula. These building blocks are generally produced in small entities which are stacked and joined at the working site, similar to the building up of a brick wall.. The capillary suction force of these materials is so strong that they can absorb substantial amounts of moisture, decreasing the insulating value of the material, depending on how they are installed.

A method of mixing in light expanded plastic particles of expanded polystyrene (EPS) in the cement mix was introduced in the 1950s and has gained some usage as lightweight ballast in concrete of higher volumetric weight, about 1000 kg/ m ³ or more, which in itself is however a considerable reduction in weight from the normal density of concrete of about2400 kg/ m ³ . The problem has been to achieve a homogeneous mix since the expanded plastic spheres float in the water mix. This problem may be overcome today and treated EPS-particles for this purpose may be bought on the market This development has also made possible the creation of the present invention.

Summary of the invention

The object of the invention is to provide a simplified, quality assured, cost effective, resource effective, environmentally friendly, non-combustible, high strength self-supporting, vapour diffusible building system based on cement or other mainly inorganic material but with low volumetric weight which thereby also gives the material an in-built insulation. Another object is to provide an "all- in-one" material in the shape of manageable and connectable building elements which will allow for a quick and quality assured construction at the building site.

Building elements according to the invention comprises highly insulating EPS- particles, or particles of other insulating material or medium, mixed into a cement mix or other mainly mineral based building compound which then cures when it reacts with water. The particles give by their mixing 4n into the wet building compound the resulting cured lightweight material a volumetric weight of aboutδO - 800 kg/ m ³ , the compression strength is more than 0,5 MRi and the coefficient of thermal conductivity λ is less than 0,15. Freferably, the volumetric weight is 300-600 kg/ m ³ of the building element and most preferred 400-500 kg/ m ³ . Freferably, the compression strength is more than 1,0 MFk and mostpreferred more than 2,0 MFk. Fteferably, the coefficient of thermal conductivity λ is less than 0,12 and mo st preferred less than 0,10.

The insulating particles are moisture-proof and have preferably a volumetric weight which is less than 50 kg/ m ³ , more preferably less than 30 kg/ m ³ . Most preferred the particles have a volumetric weight up to 15 kg/ m ³ . The volumetric weight is generally in inverse proportion to the coefficient of thermal conductivity λ, i.e. the lower volumetric weight the higher insulating value. The desired volumetric weightofthe end product may be decided according to the amount of particles that are mixed4n. Freferably a mix is used comprising at least 50 percent by volume of insulating particles of expanded polystyrene (EFS) with closed cells or other non moisture absorbing material or medium with a volumetric weight not more than 30 kg/ m ³ . Also expanding agents, air or other media may be added to the mix.

The insulating particles may have for example graphite or aluminium admixture for increased insulating performance. The insulating particles may have different fractions of different sizes for enhanced coefficient of fullness. Without different fractions airspace is formed between the concrete-covered and against each other adhering particles which thus gives the mix a lower insulating value, i.e. coefficient of thermal conductivity λ. The insulating particles may have every shape but are preferably spherical to achieve optimum strength in the concrete shell which is formed around each particle and which adhere against adjacent shell provided particles. Fbr example two fractions may be mixed where preferably the first fraction has a size up to 1,5 mm and the second fraction preferably has a size between 1,5 mm and 3 mm. The first fraction may be 20 % and the second fraction may be 80% as an example. Fbr enhanced strength in the cement mix and thus in the concrete shells, particles of glass or another aggregate element may be added. Fbr this invention, a suitable and in this way produced material mix may achieve: a) a coefficient of thermal conductivity λ of less than 0,15, preferably about 0,06-0,12, b) a compression strength of at least 0,5 MRi, preferably at least 1,0 MRi, c) a vapour diffusion resistance between 10 000 - 400 000 s/ m, preferably between 10 000 - 100 000 s/ m, mostpreferred between 10 000 - 30 000 s/ m.

The building element has infill shape, i.e. it is intended to be mounted in the open space between raised vertical elements, such as inner walls, and floor joists in order to form the outer wall. The infill element has at least one form fit suitable for the space formed by the vertical elements and the floor joists and shows a surrounding protrusion for contact against floor joists and vertical elements. In such a way the vertical elements and the floor joists will be insulated from the weather and environment present on the outside of the wall built up by infill elements.

Referably the infill elements have at least one protruding lip which extends outside the surrounding protrusion along one or two adjacent sides for overlapping a junction between adjacent infill elements in mounted position. In such a way the heat leakage and down drafting the junction between the infill elements will be minimized. Referably both the protrusion and lip are integrated cast of the same material as the rest portion of the infill element In order to further minimize the heat leakage and down draft one can seal the protrusions and/ or lips, for example using a sealing compound.

The infill element has preferably also a mounting or means for locking with the floor joists and vertical elements, respectively, for fixing the element in its mounted position

M the building elements of the invention means are possible to cast into the elements. It could for example be reinforcements, attachment means so that screws may attach properly in the building elements, frames for doors and windows, whole windows or doors, conduits for electricity or water supply and sewer systems and so on

The reinforcement may be a for each construction suitable one, two or three dimensionally shaped reinforcement structures of different designs. Fbr example metal net, in-cast in the element so the element can withstand also very high loads vertically as well as horizontally. The reinforcement structures may also be in-cast angled, trapezoid or in other form. Except as a reinforcement of the building element in its use in building constructions for example double reinforcement, i.e. two reinforcement structures in the same building element, may be an advantage in connection with the production of the building element in order to prevent the building element from warping during the drying, after the casting. The infill elements are produced in factory for later mounting at future buildings.

The inventive method of building outer walls by means of building elements according to the invention comprises the step of fitting prefabricated die -cast infill elements in the spaces formed of floor joists and vertical elements in a building framework

The building framework is erected by means of raising steel beams and/ or structural load carrying inner walls and floor joists are raised to a desired height and is finished with fitting of the roof joists. Thereafter, infill elements are mounted forming the outer walls.

On the outer wall of the building preferably a layer of plaster of a mineral base coat having a capillary suction force which is higher than the capillary suction force of the wall element The outside layer of plaster serves partially as reinforcement, smoothing, colour decor layer and moisture absorbent/ moisture regulator which guarantees that the insulating value of the wall is maintained since the pores of the wall element always are dry. The layer of mineral base coat plaster may be provided prefabricated in a factory or at the building site. As an alternative, a panel wall of, for example wood, may be mounted on the outside of the wall element with air space in between

With this building system based on light weight elements according to the invention a row of advantages are achieved in relation to known art 1) A uniform material concept for all of the infill elements, which may be made of the same type of material with the same insulating value, because no down drafts will arise in the junctions between the adjacent infill elements. 2) The building elements are non-combustible.

3)The building elements are self supported.

4) The building elements are vapour diffusible (breathe).

5) The building elements are insulating.

6) Since the building elements are prefabricated in a controlled factory environment the environmental condition problems that otherwise apply on a building site are avoided for what reason the production efficiency and the quality will be much higher and more even

Short description of the drawings The present invention will be described in more detail during referral to the attached drawings, in which

Hg. 1 shows a building element according to the present invention which has an infill shape in perspective, Hg. 2 shows the infill element of Hg. 1 from the inside, Hg. 3 shows a variant of the infill element of Hg. 1 in cross section,

Hg. 4 shows the infill element of Hg. 3 from the inside,

Hg. 5 shows an infill element according to the present invention which is provided with reinforcement in cross section,

Hg. 6 shows an outer wall during building up from the outside of a future building, and

Hg. 7 shows a mounted infill element from the inside of a future building.

Detailed description of preferred embodiments of the invention

The building elements of the invention are prefabricated in a factory. The building elements are die-castof a building compound, based on for example cement or other mainly inorganic material, which cures in a water mix, with mixingin of particles of expanded polystyrene (EPS) having closed cells or other insulating material or medium, Preferably the prefabricated elements have a size of up to 3 x 14 m, a thickness of 100400 mm and a volumetric weight of 300- 600 kg/ m ³ . The compression strength of the building element is preferably at least 1,0 MRa and the coefficient of thermal conductivity λ less than 0,15.

The insulating particles are moisture-proof and have preferably a volumetric weight which is less than 50 kg/ m ³ , more preferably less than 30 kg/ m ³ . Most preferred the particles have a volumetric weight up to 15 kg/ m ³ . The volumetric weight is generally in inverse proportion to the coefficient of thermal conductivity λ, i.e. the lower volumetric weight the higher insulating value. The desired volumetric weightofthe end productmay be decided according to the amount of particles that are mixed in. Rieferably a mix is used comprising at least 50 percent by volume of insulating particles of expanded polystyrene (EP) with closed cells or other non moisture absorbing material or medium with a volumetric weight not more than 30 kg/ m ³ . Also expanding agents, air or other media may be added to the mix.

The insulating particles may have for example graphite or aluminium admixture for increased insulating performance. The insulating particles may have different fractions of different sizes for enhanced coefficient of fullness. Without different fractions airspace is formed between the concrete-covered and against each other adhering particles which thus gives the mix a lower insulating value, i.e. coefficient of thermal conductivity λ. The insulating particles may have every shape but are preferably spherical to achieve optimum strength in the concrete shell which is formed around each particle and which adhere against adjacent shell provided particles. Fbr example two fractions may be mixed where preferably the first fraction has a size up to 1,5 mm and the second fraction preferably has a size between 1,5 mm and 3 mm. The first fraction may be 20 % and the second fraction may be 80% as an example. R>r enhanced strength in the cement mix and thus in the concrete shells, may for example particles of glass be added.

M Hg. 1 and 2 a building element according to the invention is shown having an infill shape 7. ff a building is raised by means of first erecting vertical elements or structural load carrying inner walls 3, and floor joists 4 to a desired height and is finished with fitting of the roof joists 5, the outer walls should be formed thereafter. This may be done by mounting infill elements 7 in the spaces formed between the floor joists elements 4 and the vertical elements, such as the inner wall elements 3. The inside 8 of the infill element 7 fills the space between the vertical elements and the floor joists elements 4 while a surrounding protrusion 9 abuts the vertical element and the floor joists element 4. The protrusion 9 preferably covers half of the width of the vertical elements and the floor joists elements 4. M such a way the floor joists 4 and the vertical elements 3 are insulated from contact with the outside of the outer wall and prevailing weather conditions.

M Hg. 3 and 4 a variant of an infill element 10 is shown which creates an overlap of the junctions between the adjacent infill elements 10 since one or two sides are provided with a lip 11 which covers the junctions along the lip provided sides and abuts against the sides 12 of the protrusions 9 of the adjacent infill elements 10. Referably both the protrusion 9 and the lip 11 are integrated cast of the same material as the remaining portion of the infill element 7, 10. M such a way also the junctions between the infill elements 10 are insulated. M order to further minimize the heat leakage and down draft a sealing may be provided between the lips 11 and the sides 12 of the protrusion 9, for example a sealing compound (not shown).

M Hg. 6 the startof a building construction of an outer wall by means of infill elements 10 are shown The infill elements 10 are fitted in between the vertical elements 3 and the floor joists and overlap the junctions between adjacent infill elements 10 with at least one lip 11.

The infill element 7, 10 has additionally preferably a mounting or means 17 for locking to a floor joists 4 and vertical elements 3, respectively, in order to be fixed in its mounted position, for a possible example see Hg. 7.

It is possible already during the production of the building elements to cast in reinforcements, frames for doors and windows as well as conduits for electricity and water supply and sewage systems, anchoring and other preparations. M order to facilitate later mounting of for example suspension mountings in the ready built building, plates of for example wood or expanded metal be cast into the building elements, wherein for example screws may be fixed in a secure way. The reinforcement may be a, for each construction suitable, one, two or three dimensionally shaped reinforcement structure, of for example metal net, in-cast in the element so the element can withstand also very high loads vertically as well as horizontally. The reinforcement structures may also be in-cast angled, trapezoid or in other form. M Hg. 5 a building element is shown from the end in cross section with a zick-zack shaped reinforcement structure 16. As an example metal thread having a diameter of 6-8 mm may be put together forming a net having for example openings having a size of a square decimetre. The nets may be shaped or pressed into desired shape.

Except as a reinforcement of the building element in its use in building constructions for example double reinforcement, i.e. two reinforcement structures 16 in the same building element, may be an advantage in connection with the production of the building element in order to preventthe building elementfrom warping during the drying after the casting. The in-cast reinforcement structures 16 may serve as attachment for, for example in combination with an in-cast and in the reinforcement structure welded metal plate, attachment means of the building elements.

When using anchorage reinforcement, a hole in the building element may be drilled when mounting at for example a pre marked position and then may for example so called chemical anchorage be attached. Anchoring by means of chemical anchorage may for example be used for anchoring of infill elements 7 , 10. Referably sheet metal is provided in the reinforcement net along the protrusions 9, or lips 11 so thata chemical anchorage may be fixed to the floor joists or the vertical elements and infill elements 7, 10, respectively.

The building elements may be produced in any desired design according to a geometry of a casting tool, taking practical limitations into consideration such as strength, transportation limitations etc. The building elements may for example be cast bent having any desired diameter or with any desired topographical surface profile in order to provide a living wall surface. The casting forms for the element production may be made of, for example, metal, glass reinforced plastic or other suitable material.

According to the inventive method prefabricated die -cast infill elements 7, 10 are fitted into the spaces formed by floor joists and vertical elements in a building framework Preferably they are thereafter locked by means of one or more mountings or means of attachment 17 to floor joists and vertical elements 3, respectively, see Hg. 7.

On the outer surface of the infill element preferably a layer of plaster is provided of mineral base coat having a capillary suction force which is higher than the capillary suction force of the infill element which guarantees that the insulating value of the wall is maintained since the pores of the wall element always are dry. The outside layer of mineral wall plaster serves partially as reinforcement, smoothing, colour decor layer and moisture absorbent/ moisture regulator. The layer of mineral base coat plaster may be provided prefabricated in a factory or at the building site. As an alternative a panel wall of for example wood may be mounted on the outside of the wall element with air space in between