A PROCESS FOR MANUFACTURING PREFABRICATED CONCRETE INSULATED PANELS AND PANEL OBTAINED THEREBY

Abstract

 A process for manufacturing prefabricated infill panels of the "thermal break" type for the building industry in a formwork (24), comprising a step of forming a borne layer (10) by way of casting concrete in the formwork provided with a reinforcement (28) on the bottom, laying thermal insulating strips (16A) above the casting and against its respective wall of the formwork (24), arranging connection means (18) partially buried and partially projecting from the borne layer (10) for anchoring to a bearing layer (12), positioning thermal insulating slabs (16B) to cover an upper surface of the borne layer (10), arranging lightening blocks (15), if any, casting concrete for obtaining the bearing layer (12) provided with a respective reinforcement net and irons, vibrating the concrete and, finally, taking the panel out of the formwork (24).

Description

[0001] The present invention concerns a process for manufacturing prefabricated infill panels for the building industry, of the so-called "thermal break" type, as well as a connection means which is used in said process and allows to connect the bearing layer to the borne layer in these panels, through a thermal insulation layer thereof.

[0002] Prefabricated panels of the so-called "thermal break" type consist of walls whose inner surface is thermally insulated with respect to the outer surface.

[0003] For this purpose, these panels comprise:

• a bearing concrete layer (the so-called "inner crust" of the panel) realized by way of a concrete casting and its respective reinforcement;
• a borne concrete layer (the so-called "outer crust" of the panel) also realized by way of a concrete casting and its respective reinforcement;
• a thermal insulation layer interposed between the bearing layer and the borne layer;
• connection means between the bearing layer and the borne layer, which make it possible for the latter to be structurally supported by the bearing layer.

[0004] In the bearing layer there might be possibly provided lightening cavities occupied by an appropriate lightening material, usually in the form of blocks, which is in contact with the insulating layer.

[0005] The thermal insulation level specified for the infill walls is set forth by the energy saving related regulations in force on the basis of the intended use and of the geographical area where the building is located. The specified thermal performances are obtained by acting onto the stratigraphy of the panel and, specifically, onto the thickness and the quality (thermal conductivity) of said thermal insulation layer and of the lightening material, if any.

[0006] Such types of panels are manufactured by using a conventional formwork on the bottom of which the borne layer is first realized, by means of a concrete casting which incorporates its respective reinforcement, on which a thermal insulation layer is subsequently laid, usually in the form of slabs put side by side and, subsequently, a bearing layer is realized above the insulation layer, also by means of a concrete casting which incorporates a respective reinforcement, blocks of a lightening material having previously been laid on the insulating layer.

[0007] The mentioned connection means interconnecting the two crusts of the panel (the "bearing" and the "borne" ones) shall feature such characteristics as:

• to assure a "mechanical" support of the borne layer of the panel by the bearing layer;
• to prevent thermal bridges from forming in proximity to the connection means due to the necessary approximation induced by the "traditional connection systems" in drilling and/or putting the slabs of thermal insulating material side by side;
• to allow for a sufficient "slip" of the (outer) borne layer with respect to the (inner) bearing layer, due to the different thermal expansions that the two layers might undergo, because of their positions, whenever the panel is part of a building.

[0008] The most traditional connection means include simple sections of steel rod, of appropriate lengths, arranged properly spaced from each other and connected at one of their ends (like a comb), everything making-up an approximately 2-meter long assembly which is rather bulky to handle and transport.

[0009] Should this traditional type of connection means be used, the manufacture of a panel takes place according to the following successive steps:

• the reinforcement net of the borne layer is laid on the bottom of the formwork, and said comb-like connection means are laid above it in the appropriate positions which usually coincide with those of the ribs of the bearing layer of the panel, along with the connection sections facing vertically upwards;
• a concrete casting is performed to form the borne layer, followed by a respective vibration step thereof;
• slabs made from the selected thermal insulation material are put side-by-side and superimposed to said casting with the purpose of completely covering the formwork and thus realizing the insulation layer of the panel. However, it is worth noting that such slabs shall be forced downwards in order for said vertical sections of the connection means to penetrate the slabs in order for them to be capable of operating as a connection between the just realized borne layer and the bearing one to be realized;
• blocks of a lightening material, if any, are laid above the insulating slabs;
• the reinforcement irons of the bearing part (reinforcement rods and nets) are laid and a final concrete casting is made so as to get the bearing layer.

[0010] However, this process implies a number of non-negligible drawbacks.

[0011] A drawback consists in that, as already said above, the ("comb-like") connection means shall be supplied in packages having a dimension of not less than 2 meters, hence they are rather bulky with reference both to transportation and to storage.

[0012] A further drawback is related to the fact that these connection means arranged in the formwork must be secured to the reinforcement net of the borne layer, in order for said sections to retain a vertical position whenever the insulating slabs are pressed thereon to bore them through.

[0013] This operation also results in a further drawback, consisting in that, being it necessary to force the insulating slabs onto said sections, it might happen that they are finally not perfectly put side-by-side each other. As a matter of fact, it rather frequently occurs that a gap remains between adjacent insulation slabs, which makes-up an undesired thermal bridge.

[0014] A further drawback consists in that insulating slabs, made from a material that allows for said sections to bore through such slabs, shall be used with this system consequently the latter cannot be made from an insulating material featuring a high density (such as, for instance, polyurethane, cork, or rock wool), with the consequent impossibility of obtaining panels featuring high thermal performances (i.e. panels featuring a low thermal transmittance).

[0015] Other manufacturers of thermal break panels use elements made from a plastic material in the form of a flattened arrow as connection means. After casting the borne layer and superimposing insulation slabs thereonto, such connection means are forcedly inserted, one by one, through such slabs until boring their tip into the borne concrete layer. Such system entails a risk that the connection means used, while being inserted, get in contact with the reinforcement net or granules of inert materials, which prevent a correctly positioning in and "adhesion" to the born layer.

[0016] In addition, in this case too, it will not be possible indeed to use insulating slabs made from a material featuring a high density, with the consequent impossibility of obtaining panels featuring high thermal performances (i.e. panels featuring a low thermal transmittance).

[0017] Connection means are also used consisting of flattened elements, made from a thermosetting resin reinforced with fiberglass, one end of which is connectable to the reinforcement net of the borne layer before its respective concrete is cast.

[0018] However, such system implies the need for securing the connection means to the arc-welded net and for performing numerous "tailored cuttings" on the formwork of the various thermal insulating slabs because the connection, which shall be accommodated in the space adjacent to the various insulating slabs, are arranged in different positions of the panel and with different orientations.

[0019] Connection means consisting of fattened elements, made from a thermal non-conductive material, are also known and described in document US2003/0208987.

[0020] This system too features the major drawbacks related to the manufacture of the connection means themselves being complex and to the need for making cuttings or similar pockets therein to be able to match and couple with the reinforcement bars.

[0021] Another known solution used for reinforcing the concrete material is described in document EP2295665 and is based on the use of reinforcement and stiffening elements arranged according to a longitudinal direction of development of the formwork to form the panel and reinforcement means arranged transversally to the longitudinal reinforcement means and secured to said longitudinal reinforcement means and, additionally, pivots made from a metal, or wood, or a resin or another suitable material and which are arranged between at least one out of the inner and outer layers or develop starting from a metal net.

[0022] This solution also presents drawbacks related to its manufacture being complex.

[0023] An object of the present invention is to obviate the above described drawbacks.

[0024] More specifically, an object of the present invention consists of realizing a connection means and a process for manufacturing prefabricated infill panels, of the thermal break type, that do not present the above described drawbacks affecting the currently used systems and processes.

[0025] A further object of the present invention is to put at users' disposal a connection means to be used in manufacturing prefabricated infill panels, said panels featuring high efficiency and reliability values over time, said connection means being cost-effective and easy to implement.

[0026] These objects and others are achieved by the invention according to claim 1.

[0027] According to the invention, a process is provided for manufacturing prefabricated infill panels of the "thermal break" type for the building industry in a formwork, comprising the following steps: forming a borne layer by way of a concrete casting in the formwork provided on the bottom of a reinforcement, laying thermal insulation strips above the casting and against its respective wall of the formwork, arranging connection means partially buried in and partially projecting from the borne layer for their anchoring to a bearing layer, positioning thermal insulation slabs to cover an upper surface of the borne layer, arranging lightening blocks, if any, casting concrete to obtain a bearing layer provided with its respective reinforcement net and irons, vibrating the concrete and, finally, taking the panel out of the formwork.

[0028] Advantageous embodiments of the invention are apparent from the dependent claims.

[0029] The invention, with reference to its own construction and functional characteristics, will be more apparent from the following description, wherein reference is made to drawings which illustrate an embodiment provided for explanatory purposes only and wherein:

figure 1 schematically shows a partial cross-sectional view of two adjacent prefabricated infill panels of the thermal break type, implemented according to the invention;

figure 2 schematically shows an axonometric view of the connection means used in the process according to the present invention;

figures 3 thru 7 schematically show some steps of the process according to the invention.

[0030] With reference to figure 1, each of the two adjacent panels shown therein comprises:

• a borne layer 10 made from concrete wherein a respective reinforcement is incorporated, typically consisting of an arc-welded steel net (not represented for the sake of simplicity);
• a bearing layer 12, also made from concrete with an arc-welded steel net buried therein, and additionally other reinforcements in correspondence with aboard ribs 14 which the bearing layer 12 is usually provided with (the net and reinforcements additional are also omitted for the sake of simplicity);
• a thermal insulation layer 16 interposed between the bearing layer 12 and the borne layer 10;
• lightening cavities cut in the bearing layer, occupied by appropriate blocks 15 made from a lightening material.

[0031] Just as an example, the borne layer might have a thickness of 6 cm, the bearing layer a thickness of 14 cm, and the insulation layer a thickness of 8 cm, totaling 28 cm.

[0032] Figure 1 does not show, for the sake of simplicity, the connection means that allow the bearing layer 12 to support the borne layer 10. As already mentioned before, such connection means might be of different types, all of which feature a number of drawbacks.

[0033] With special reference to figure 2, this shows an embodiment of the connection means 18, used in the process according to the present invention.

[0034] As schematically shown in figure 2, it comprises two parallel and spaced away sections 20, which will be referred to as connection sections below, a corresponding end of which is connected by a part 22, which will be referred to as support part, being it shaped in such a way as to determine a support plane for the connection means 18. The support part 22 is formed of three consecutive C-shaped sections. The connection means 18 is, in this specific case, obtained by properly bending a piece of steel rod.

[0035] Preferably are the ends 21 of the connection sections 20 opposed to the support part 22, 90-degree bent to improve the anchoring of the connection means 18 to the bearing layer 12.

[0036] A connection means 18 having dimensions suitable for the above mentioned explanatory dimensions of the panels according to figure 1 might, for instance, be obtained starting from an AISI 304 austenitic steel rod with a diameter of 4 mm and comprising two connection sections 20 having a length equal to 20 cm or more, if so requested by the prescriptions of use of the system, with a terminal bending of 3 cm and the support part 22 having dimensions equal to 10 x 25 cm.

[0037] It goes without saying that the connection means according to the present invention might have a shape different from that shown in figure 2. In particular, that section of steel rod which is used to form the connection means might be shaped differently from that illustrated in such figure. As a matter of fact, the support part 22 which, in the preferred embodiment according to the figures, is C-shaped, might be V-shaped or arc-of-circumference-shaped or even be broken-line-shaped, provided it keeps defining a support plane.

[0038] In addition, the 90-degree bent ends 21 might be oriented differently (for instance, they might face sidewards instead of frontwards, provided they ensure the anchoring of the bearing part of the panel to the filling concrete.

[0039] Let's now describe an embodiment of the process according to the present invention, the individual steps being illustrated with reference to figures 3 thru 7.

[0040] Figure 3 schematically shows a formwork 24 which is used to manufacture a prefabricated infill panel of the thermal break type, the formwork having been cross-sectioned with a vertical plane to make it possible to better look at its inside, as well as to show how the formation of the layers making up the panel takes place.

[0041] On the bottom 26 of the formwork 24 there is laid a conventional arc-welded net 28 which will make-up the reinforcement specified for the borne layer (10 in figure 1) of the panel to be manufactured.

[0042] Then a concrete casting is made, according to a determined quantity and quality, so as to obtain a borne layer having the specified thickness (figure 4), a casting that incorporates the net 28 and shall obviously be submitted to vibrations by using conventional means (not shown) in order to obtain a borne layer 10 as much compact as possible.

[0043] Supposing that the panel to be manufactured has a bearing layer 12 (figure 1) provided with perimetric ribs 14 only, at this point strips 16A (figure 5) cut from slabs of a given thickness, made from the thermal insulation material to be used, are laid above the casting of the borne layer 10 and well against the side walls of the formwork 24. The strips 16A shall have a width equal to the distance that both connection sections 20 of the connection means 18 (figure 2) shall have from their respective edges of the panel to be manufactured. For instance, if the aboard rib 14 of the bearing layer 12 of the panel (see figure 1) has a width of 25 centimeters, then its respective insulation strip 16A might have a width of 12 centimeters and the vertical sections 20 of their respective connection means 18 will be made lean against the edge of the strip 16A.

[0044] Therefore, the insulation strips 16A make it possible to visually determine, in a practical and accurate manner, the position that said connection means 18 shall have with respect to the respective side wall of the formwork 24 (a position whereby the connection sections 20 are substantially anchored to the middle of the respective aboard rib of the panel), thus making the positioning of such connection means in the formwork very easy. As a matter of fact, it will be sufficient to bury the connection means 18 in the still fluid concrete, in the number specified by the prescriptions of use of the system, so that their two connection sections 20 abut the inner edge of the respective insulation strip 14A, as shown in figure 6. This figure also shows that from the borne layer 10 that is going to consolidate only the upper part of the connection sections 20 of every connection means 18 projects upwards, such end obviously having to also go beyond the upper surface of the insulation strips 16A to be subsequently be able to sufficiently anchoring to the bearing layer 12 (figure 1) of the panel that will be manufactured.

[0045] Should it be deemed appropriate, it is also possible during this operating step, just after putting the connection means 18 in position, to also bury a reinforcement bar in the concrete, which leans on the support part 22 (figure 2) of the connection means 18, in order to improve the anchoring of the latter to the borne layer 10. Figure 6 shows that in this specific case such anchoring bars, identified by the reference numeral 30, may conveniently concern more than one connection means 18.

[0046] Subsequently (figure 7), that part of the layer 10 which remains uncovered is covered with thermal insulation slabs 16B, of the same type as those from which the insulation strips 16A had been derived, in order to complete the thermal insulation layer 16. For this purpose, it might obviously occur that some of the slabs 16B have to be trimmed in order to match their dimensions to the dimensions of the area to be covered. It is apparent that the slabs 16B shall be trimmed, if necessary, as much accurately as possible and that conveniently will they be laid in a little forced position so that their edge presses the edge of an adjacent slab or strip, in order to prevent gaps from forming (which would make-up a thermal bridge), consequently the connection sections 20 will in practice be caught between them, a result that can be obtained thanks to the fact that usually the material that these slabs are made from features a certain deformability.

[0047] Concerning the subsequent steps of the process, they are fully conventional ones and consequently they are not illustrated in the figures nor are they described in details, being them apparent to those skilled in this sector. It will be enough to say that blocks 15 of a lightening material, if any, will be laid above the thermal insulation layer 16, and likewise reinforcing cages for such ribs and a reinforcement net for the bearing layer will be arranged in a conventional manner. Then a concrete casting will be made along with its respective vibration, thus completing the bearing layer 12 of the panel. Finally, the latter will be removed from the formwork 24, once the time specified in order for concrete to be sufficiently set to perform such operation has elapsed.

[0048] Let's also point out that, if the panel to be manufactured also includes one or several intermediate ribs of the bearing layer 12, and consequently connection means 18 shall also be provided at such ribs, it will be enough to operate in such a way that, when burying the connection means 18 corresponding to the aboard ribs 14 in the concrete of the borne layer 10, the connection means 18 relevant to the intermediate ribs be also buried in the specified position, then paying attention in order for the connection sections 20 projecting from the concrete in correspondence with said intermediate ribs to be caught between two adjacent thermal insulation slabs 16B, a trimming of said slabs being possibly required in order to make their dimensions match, in order to complete thermal insulation.

[0049] It is apparent from the previous considerations that the process according to the present invention, also thanks to the use of the connection means 18, which shall not be connected to the reinforcement net of the borne layer 10 of the panel, make it possible to get an accurate positioning of said connection means with respect to the respective side wall of the formwork 24, whereby they can be conveniently placed in the preset positions by simply burying the support parts of each individual connection means 18 in the concrete of the borne layer 10, until its support part 22 (which, as already said, defines a support plane) leans on its respective reinforcement net 28.

[0050] An optimum anchoring of the connection means 18 to the borne layer 10 is also warranted, thanks to the shape of the support part 22, and even more if the above mentioned additional anchoring bar (for instance the bar 30 in figure 6) is used.

[0051] It is also worth pointing out that the connection means can be obtained in an extremely simple and convenient manner starting from simple easily shapeable steel rods (in particular, in the shape of figure 2, even though, as already said, other shapes could be used), being it possible in anyway to obtain connection means featuring a high mechanical strength, not jeopardized by the presence of welds, and high cost effectiveness.

[0052] It is also worth pointing out a further advantage consisting in that the distribution of these connection means feature wide margins of discretion, in that, being such connection means independent of each other, they can be made more or less frequent depending on the actual requirements (provided the prescriptions of use of the system are met). Also, thanks to their shape, a high number of such connection means can be grouped together in a very reduced volume, consequently they are easy to transport and to store and can be conveniently handled individually, the weight of one single connection means being very light and its overall dimensions very small.

[0053] In addition, as a consequence of the accurate distance from the respective outer edge of the panel at which the connection means can be placed thanks to the process according to the present invention, because of the fact that they are made lean against the edge of the respective thermal insulation strip, it is also possible, by following the previous explanations, to prevent gaps from forming between the insulation strips and the adjacent insulating slabs and even between adjacent insulating slabs. Since the strips 16A are pushed against their respective side wall of the formwork 24, a certainty is also achieved that the insulation layer of the panel is flush with the edge of the panel, thus preventing the insulation layer from being set back with respect to such flush line (a drawback that is non unfrequently found in thermal break panels manufactured according to the known processes), such gaps resulting in thermal bridges in correspondence with the junction between two panels put side-by-side that form a wall.

[0054] Finally, it has been possible to find out that the connection means 18 allow for an optimum "slip" of the (outer) borne layer with respect to the (inner) bearing layer, due to the different thermal expansions.

Claims

1. A process for manufacturing prefabricated infill panels of the "thermal break" type for the building industry, characterized in that it comprises the following steps:

- on the bottom of the formwork (24) used to manufacture the panel, casting concrete for obtaining a borne layer (10), and incorporating a respective reinforcement (28) arranged on the bottom of said formwork (24) beforehand or during an intermediate casting step;

- vibrating the casting;

- arranging above the casting and against its respective wall of the formwork (24), in correspondence with every edge of the panel where the aboard ribs of a bearing layer (12) of its own will be formed, thermal insulation strips (16A) cut from slabs (16B) made from a thermal insulation material;

- arranging connection means (18), partially buried in the concrete of the borne layer (10) in predetermined positions corresponding to the aboard ribs (14) of the bearing layer (12), each of said connection means (18) comprising two connection sections partially projecting from the casting in order for them to be subsequently anchored to the bearing layer (12) of the panel and a support part bent in such a way as to define a support plane for every connection means with respect to the reinforcement (28);

- covering part of the upper surface of the concrete of the borne layer (10) not covered by the thermal insulation strips (16A), with the possibly trimmed thermal insulation slabs (16B);

- arranging lightening blocks (15), if any;

- casting concrete to obtain the bearing layer (12), after laying its respective reinforcements net and other specified reinforcement, if any, and vibrating the concrete;

- taking the panel out of the formwork (24).

2. A process according to claim 1, characterized in that it comprises a step of burying connection means (18) in the concrete of the borne layer (10) corresponding to intermediate ribs, said step being performed in the case that the bearing layer (12) of the panel includes an intermediate rib and together with burying the connection means (18) corresponding to the aboard ribs in the concrete of the borne layer (10).

3. A process according to claim 1, characterized in that it comprises a step of burying a reinforcement bar (30) in the concrete which couples with and overlaps one or several connection means (18) to improve the anchoring of the panel to the borne layer (10) of the panel, said step being performed after the step of burying said connection means.

4. A process according to any of the previous claims, wherein the thermal insulation material that the strips (16A) and the slabs (16B) are made from is of a high-density type, such as polyurethane, cork, or rock wool.

5. A prefabricated infill panel manufactured according to the process according to the previous claims, characterized in that it comprises connection means (18) derived from a steel rod bent in such a way as to define two connection sections (20) parallel to and spaced from each other and a support part (22) which develops between the corresponding ends of the two connection sections (20) and is shaped in such a way as to define a plane perpendicular to said connection sections (20).

6. An infill panel according to claim 5, characterized in that in the connection means (18) the end (21) of each of the two connection sections (20) that is opposed to the support part (22) is 90-degree bent to improve anchoring.

7. An infill panel according to claim 5 or 6, characterized in that the connection means (18) has the support part (22) obtained by C-bending its respective part of the reinforcement steel rod.

8. An infill panel according to any of claims 5 thru 7, characterized in that the reinforcement rod that forms the connection means (18) is made from AISI 304 steel.

Drawing