WO1994023143A1

WO1994023143A1 - Method for manufacturing concrete elements and a concrete element manufactured according to the method

Info

Publication number: WO1994023143A1
Application number: PCT/SE1993/000268
Authority: WO
Inventors: Henry Jugas
Original assignee: Ab Dala Cementvarufabrik
Priority date: 1991-10-18
Filing date: 1993-03-30
Publication date: 1994-10-13
Also published as: SE9203033L; SE501752C2; EP0692050A1; NO953848L; FI954633A; NO953848D0; NO311773B1; SE9203033D0; FI954633A0; AU4095993A; SE9103042D0

Abstract

A method of manufacturing insulated concrete elements (2) comprising at least one supporting concrete layer (6) and at least one insulation layer (12). Recesses (14) are made in the insulation layer to form channels (20), made by mechanical working, said working giving the interior of each channel a rough surface (22). Fresh concrete (25) is poured into a mould (24) which has been pre-equipped with reinforcement (28) to make the supporting concrete layer (6) and the insulation layer (12) is then pressed against the concrete in the mould. The concrete is made, through vibration, to fill out each channel (20) and after hardening, constitutes both the supporting concrete layer (6) and ridges (10), integral with the concrete layer, in each channel (20). The ridges serve as anchoring means for the insulation layer. The channel in cross section can be T-shaped, dovetailed, or U-shaped.

Description

Methodfor manufacturing concrete elements and a concrete element manufactured according to the method

The invention relates to a method of manufacturing an insulated concrete element according to the preamble of Claim 1, and a concrete element manufactured according to said method, of the type disclosed in the preamble of Claim 9.

Insulated concrete elements of conventional type, for example for outer walls, supporting inner walls or floors, are normally made as sandwich elements consisting of two concrete layers interconnected by reinforcement ladders. The inner layer is a supporting layer and the outer layer serves as a wall covering. There is an in¬ sulating layer between these two layers. Sandwich elements are as a rule one storey high but are also made as spandrel elements or in even larger dimensions, e.g. for use in industrial structures. It is also possible to prehang the windows and doors at the factory, so that the climate shell of the building will be complete as soon as the wall elements are mounted in place. Experience has shown that damage to such premounted windows during transport and assembly is quite rare. The mounting of hardware can also be completed at the factory. The wall element can also be cast with spaces for plumbing, electrical and telephone installations. The connections between the different wall portions are easily done as is the sealing for fire and noise protection. The inside can be made smooth so that it can be painted with a minimum of preparation. The outside can be made with various structures and surface treatments. Up to now, this has been the best wall element from a technical and economial point of view, since a complete wall portion is made in one step when the element is put in place. Conventional concrete elements must, however, be mounted with visable joints between adjacent elements in order to be able to compensate for movements occurring in the outer layer due to temperature variations.

The manufacture of a conventional wall element comprises the following steps:

Form oil is applied to a table form and stop ends are mounted in place to define the surfaces of the element. The reinforcement is then prepared and placed on the table form and a first casting of a first concrete layer is done. The reinforcement comprises a welded mesh in which reinforcement ladders are tied securely with a predetermined spacing. When the casting is finished, i.e. when the concrete has hardened, insulation in the form of hard mineral wool is supplied onto the first concrete layer between the ladders and a welded mesh is tied to the reinforcing ladders on top of the layer of insula¬ tion. The second concrete layer is cast directly on the mineral wall or, alternatively, the entire package, with the first concrete layer, the mineral wall and the second welded mesh, is lifted by a lifting means, is turned over and is emersed in wet concrete in the table form. Any wall surface treatment necessary is done thereon, and the element is then ready for delivery. The wall surface treatment can include rolling or raking or the form can be coated before casting with a so-called retarder to delay hardening of the surface layer itself, so that a portion of the material can be washed off to partially expose the aggregate.

It is obvious that the manuf cturing process described above involves the use of complicated mounting devices or methods which are unnecessarily time-consuming, since when the insulation is used as a casting form, another surface structure is attained than when the concrete is cast in a steel form. The surface must be smoothed with a steel blade, which is time-consuming since the smoothing cannot be done until it has reached a certain hardness (after about 1-2 hours), and the concrete element must remain in the form until it is completely hardened. This gives rise to delays in the manufacturing process. Sub¬ stantial time-savings will be achieved if the second concrete layer can be eliminated. This will also eliminate the mechanical fixing of this layer to the first concrete layer facing the inside of the structure.

The conventional concrete or wall element thus has a number of major disadvantages, it being heavy and difficult to handle, and gives rise to unnecessarily thick walls in addition to being time-consuming and complicated in manufacture and thus costly.

The purpose of the present invention is therefore to define a method of manufacturing a concrete element which has the good properties of the sandwich element but in which the above indicated disadvantages have been removed, and a concrete element manufactured according to said method.

This purpose is achieved according to the invention by virtue of the fact that the method is characterized by those features disclosed in Claim 1 and by an element which has those features disclosed in Claim 9. Preferred methods, preferred embodiments and preferred further developments and improvements are disclosed in the subclaims.

By virtue of the fact that according to the invention the outer concrete layer is eliminated and the insulation is used as a plaster substrate or by virtue of the fact that fixing means which extends through the insulation and are designed for alternative wall covering are cast into the inner concrete layer, the following advantages, among others, are achieved:

- 40-50% lower weight which reduces production cost, transport cost and assembly cost. Compared with conven¬ tional on-site construction, the structure building cost can be reduced by as much as 20%.

- By virtue of the fact that the outer wall covering is done at the site, the prefabricated structure will have the appearance of a building built completely at the site. There are no external joints, which present both technical and aesthetic problems.

- Alternative wall covering possibilities will make it possible to infinitely vary the exterior of the structure.

- By reducing the total weight of the structure, it is in certain cases possible to avoid foundation reinforcement in the form of piling.

- Interior details such as reveals can be made as needed with millimetre precision. The concrete surface facing the interior of the structure will have a good surface finish and be ready for painting without spackling.

- By virtue of the fact that the concrete slab faces inwards without any insulation thereon, it also serves for heat storage.

- For joints between elements, the required profiling can be optimized with high precision, e.g. as regards the thickness of the insulation and the joints, and combined lifting eyes/anchoring means can be cast into each element with exact placement and orientation. The anchoring means can, for example, be cast into the adjacent floor structure, which is cast on site.

- When a wall element is cast on site, the profiling of the joint portion will cause the concrete to tend to push away the insulation causing it to float up and the joint will consist partially of concrete straight through the wall. Thus the insulation will be uneven and difficult to control in the building stage.

- Prefabricated concrete elements according to the invention are preferable for environmental reasons as wells, since spackling is eliminated which can induce allergies, as well as sanding dust which is created when the casting joints are sanded off on the outside concrete element. Compared with walls cast on site, no time- consuming plugging of form tie holes is required.

- The choice of wall covering is flexible. Base plastering can be done at the factory, which provides uniform high quality.

The manufacture of a concrete element according to the invention is done initially in the same manner as accord- ing to the conventional technology, up to the application of cement for casting the first concrete layer. In order to keep the insulation in place on the concrete layer, some kind of fastening device must be used between the insulation and the concrete sheet. By using sheets of insulation as moulds for reinforcing ridges and pressing the sheets into a mould provided with reinforcement and filled with fresh concrete produces, when the concrete has hardened, a concrete element with a smooth concrete surface and insulation securely cast thereto. Each sheet of insulation is suitably cut out so that at least one recess with a shoulder is formed adjacent to each of two opposite edges of the sheet. By pressing the sheets down into the wet concrete, either individually or together as a unit so that the shoulders on two sheets lying edge to edge are adjacent, channels are formed on the side of the insulation material facing the concrete. -Alternatively, each insulating sheet is made with tightly spaced grooves over the entire surface of the sheet, forming relatively shallow channels relative to the recesses. The concrete penetrates into the channels and is caused to fill them up completely by vibrating the concrete. .Any enclosed air will exit through the gaps between the sheets or through the insulation material itself.

When the concrete has hardened, a concrete slab is obtained with concrete ridges which are, as the case may be, dovetail-shaped, T-shaped or rectangular, said ridges fitting into corresponding dovetail-shaped, T-shaped or rectangular channels in the insulation material. Each of these concrete ridges serves as an anchoring means for the insulation.

According to a preferred embodiment, each shoulder is made so that the channel formed by two adjacent shoulders has in cross-section a greater width in its inner portion than in its outer portion. This assures secure anchoring of the insulation in the concrete. The cross-section of the channel can be either dovetailed or T-shaped. A dovetail channel is provided by sawing the recess out at a suitable angle. The T-shape is achieved by routing out a groove in the recess adjacent to and parallel to the shoulder forming the bottom of the channel.

If a wall covering requiring special anchoring means is to be put up, it is suitable to cast in a stud provided with anchoring means for the wall covering. Embodiments of the invention will be described in the following, as examples only, with reference to the accompanying schematic drawings.

Fig. 1 shows insulation consisting of a group of sheets of insulation lying adjacent to each other, Fig. 2 shows a mould provided with reinforcing ladders and filled with reinforced concrete, Fig. 3 shows the mould according to Fig. 2 in cross- section along the line A-A,

Fig. 4 shows a hydraulic pressing means disposed on the mould,

Fig. 5 shows a finished concrete element,

Fig. 6 shows a concrete element covered with stone, said element having dovetailed channel,

Fig. 7 shows a concrete element covered with wood, which has channels with straight parallel lateral surfaces, Fig. 8 shows a concrete element with a plaster front, said element having channels with T-shaped cross-section, Fig. 9 shows a supporting inner wall in section, having a core of insulation with channels on alternating sides, Fig. 10 shows in section the construction of outer wall elements at a joint between two elements and a concrete floor structure, Fig. 11 shows a portion of an insulation sheet which has a channel with a U-shaped cross-section.

The manufacture of concrete elements according to the invention, "CONCELL CONCRETE ELEMENTS", proceeds as follows. A concrete element 2 is dimensioned according to applicable specifications as regards supporting function, insulation, fire protection, noise insulation and any specific functional requirements. Control plans and check lists for the product are established. The element 2 is built up essentially of an insulation block 4 and a reinforced concrete layer 6 which are joined together by openings 8 in the insulation block, said openings surrounding anchoring ridges 10. The insulation block is composed of insulation sheets 12, preferably of cellular plastic, provided at adjacent facing edges with recesses 14 and shoulders 16. When the insulation sheets are joined together into an insulation block along a joint line 18 located between adjacent sheets, the recesses and shoulders of the adjacent insulation sheets form channels 20. Depending on the form of these recesses and shoul¬ ders, channels 20 with varying cross-sections can be formed, dove-tailed, T-shaped or U-shaped cross-sections being preferable. The channels 20 are suitably made by sawing out or routing out the recesses 14 and shoulders 16, the defining surfaces of the channels 20 being roughened up thereby and having a rough surface layer with many small projections 22. Ordinary sawing can provide a positive grip depending on the structure which is produced in the saw-cut.

A casting mould 24 of steel is cleaned and oiled. Stop ends (not shown) are set in place to limit the outer dimensions of the element. The mould has a mould edge 26 at either end. In a conventional manner, a prefabricated mould for doors or windows is fixed as needed with magnets (not shown) . Electrical boxes and smaller com- ponents to be cast in the concrete are fixed with hot melt adhesive, for example. A prefabricated reinforcement cage comprising spacers and reinforcement ladders 28 which are known per se is placed in the mould and is fixed therein. The reinforcement ladders are oriented as shown in Figs. 2 and 3 with a spacing which is adapted to the corresponding spacing between the channels in the insulation sheets or which agrees with the outer dimen¬ sions of the sheets. The insulation sheets 12 are pre¬ pared as specified above and the mould 24 is filled with a calculated amount of fresh concrete which is prelimina¬ rily smoothed off. The insulation block 4 is placed above the concrete in the form with the aid of a lifting and

the element is achieved. At the same time as the insulation block 4 is pressed down, the concrete is vibrated by means of conventional vibrators arranged in the mould. This causes the concrete to penetrate into each groove or channel 20 and the vibration is terminated only when no further sinking of the insulation block is noticed and the intended thickness of the element has been achieved. The concrete should then have been pressed up along the outer edges and thus fill out the entire space under the insulation. The lifting and pressing means 30 are removed from the casting mould 24, which is transferred to a hardening chamber (not shown) , in which the concrete is quickly hardened by using the released heat of the reaction, which as a rule is sufficient to maintain a continuous temperature of about 40°C. When the concrete has been completely hardened, the mould is removed from the hardening chamber and the finished element 2 is removed from the mould.

After removal, plaster is supplied if necessary or the insulation is ground down to the exact thickness. A wall covering 50 is applied to the outside of the concrete element. Alternative wall coverings are brick, wood or plaster. A brick siding 50 is fixed to the concrete element by means of wall ties 52 cast into each anchoring ridge 10 and which anchor the brick siding in a known manner (Fig. 6). A wooden siding 50 is fixed to braces 54 cast in the concrete in a corresponding manner (Fig. 7). Plastering is done with the aid of a track-mounted plastering roller of conventional type which provides a good plaster undercoating. With the aid of a conventional vibrator beam, the plaster is vibrated in place in the right thickness. A mesh reinforcement may be pressed down to about half of the thickness of the plaster and the plaster 50 be smoothed off by means of an angled steel blade (Fig. 8). The element is inspected and then placed upright on a transport pallet. By pressing into the wet concrete insulation sheets provided with dovetail or other grooves for the purpose of fixing the insulation to the concrete, after the concrete has hardened there will be a good attachment to an otherwise smooth concrete slab. Since the concrete is cast in a steel mould, a surface finish which is ready for painting is obtained at the same time on the side of the concrete facing the inside of the structure, even including window reveals and the like. The plaster layer applied directly to the outside of the insulation sheet or onto a plaster carrying mesh, is elastic and is able thereby to absorb stresses arising through temperature variations, thus making possible a plaster wall covering which is free from joints.

Finally, it must be pointed out that the present invention must not be considered limited to the special embodiment described above. Rather, the invention com¬ prises all those embodiments and equivalent solutions which fall within the scope of the following patent claims.

Claims

1. Method of manufacturing insulated concrete elements, comprising at least a supporting concrete layer and at least one insulation layer, c h a r a c t e r i z e d in that the insulation layer (12) is made with recesses (14) which form channels (20), that the cross-section of each channel (20) is formed by mechanical working, said working providing a surface of the delimiting surfaces of the channel which has small projections (22), that fresh concrete (25) is supplied to a mould (24) which has previously been provided with reinforcement (28) for achieving the supporting concrete layer (26), that the insulation layer (12) is pressed against the concrete in the mould, that the concrete (25) by vibration is caused to fill out each channel (20), and that the concrete, after hardening, on one hand, constitutes the supporting concrete layer (6) and, on the other hand, ridges (10), integral with the concrete layer, in each channel (20), said ridges serving as anchoring means (10) for the insulation layer ( 12) .

2. Method of manufacturing concrete elements according to Claim 1, c h a r a c t e r i z e d in that the insulation layer (12) forms a mould (24) which is pre- equipped with reinforcement (28) and in that concrete is cast on the reinforced insulation layer.

3. Method of manufacturing concrete elements according to Claim 1 or 2, c h a r a c t e r i z e d in that the cross-section of each channel (20) is made with an inner portion which has a greater width than an outer portion adjacent to the plane of the insulation layer (12) facing the concrete.

4. Method of manufacturing concrete elements according to Claim 1 or 2, c h a r a c t e r i z e d in that the cross-section of each channel (20) is made with straight lateral surfaces (14) oriented essentially at right angles to the plane of the insulation layer (12) .

5. Method of manufacturing concrete elements according to one or more of Claims 1-4, c h a r a c t e r i z e d in that the reinforcement is made in the form of reinforce- ment ladders (28), the portions of which facing the mould are tied to a welded mesh reinforcement disposed parallel to and at a predetermined distance from the flat bottom of the mould (24), and in that the portions of the reinforcement ladders (28) facing away from the mould (24), during casting extend outside the top side of the fresh concrete (25) in the mould.

6. Method of manufacturing concrete elements according to Claim 5, c h a r a c t e r i z e d in that the projecting portions of the reinforcement ladders (28), when the insulation layer (12) is pressed against the concrete, are enclosed in the concrete which fills out the channels (20) of the insulation layer, and in that each channel (20) is formed from recesses (14) made adjacent to two facing edges of the insulation layer (12).

7. Method of manufacturing concrete elements according to one or more of the preceding Claims, c h a r a c t e r - i z e d in that each channel is formed of two recesses for channels (20) running parallel to two facing edges of the insulation layer, which have been made in the insulation layer (12) evenly spaced over the plane of the layer with a spacing preferably corresponding to the width of the channels .

8. Insulation concrete element manufactured according to one or more of the methods according to Claims 1-7 and comprising at least one supporting concrete layer and at least one insulation layer, c h a r a c t e r i z e d in that the insulation layer (12) has recesses (14) and shoulders (16) forming channels (20), that each channel (20) has a dovetail cross-section, and that the concrete layer (6) has ridges (10) formed integrally therewith which fit exactly into each channel (20).

9. Concrete element according to Claim 8, c h a r a c t e r i z e d in that each channel (20) has a T-shaped cross-section.

10. Concrete element according to Claim 8, c h a r a c t e r i z e d in that each channel (20) has a U-shaped cross-section.