DE102020125111A1 - Process for treating wooden ceilings in buildings, in particular for treating listed wooden ceilings in buildings - Google Patents

Abstract

The invention relates to a method for treating wooden ceilings, in which a plurality of spaced-apart shear connectors (1) are first screwed into a wooden ceiling (7) of a building without pre-drilling or without pre-drilling, with only a partial area of the shear-tie anchors (1) being screwed into the wooden ceiling (7) are screwed in and a screw protruding area (6) protrudes from the wooden ceiling, and an in-situ concrete and/or topping is then applied to the wooden ceiling (7) in such a way that the screw protruding areas (6) of the shear connector (1) are anchored in a concrete slab (5) that is then formed after the in-situ concrete and/or top-up concrete has hardened, and a composite wood ceiling (2) is produced as a shear-resistant connection between the wooden ceiling (7) and the concrete slab (5). According to the invention, the concrete slab (5) is removed again for non-destructive dismantling of the composite wood ceiling (2), with the shear connector (1) then being removed from the wooden ceiling (7). A screw channel (22) remains in the wooden ceiling (7). A wood-swelling medium (25), in particular water or steam, is then introduced into the screw channel (22), so that the wood displaced by the respective shear connector (1) and/or surrounding and/or forming the screw channel (22) swells and the Screw channel (22) essentially fills and/or closes.

Description

The invention relates to a method for treating wooden ceilings in buildings, in particular for treating listed wooden ceilings in buildings, according to the preamble of claim 1.

Especially in the field of building renovation, the wood-concrete composite technology represents a favorable method, for example, to improve existing wooden ceilings both in terms of statics (load-bearing capacity, in terms of building physics, soundproofing, fire protection) and with regard to a simple type of execution, in order to achieve new building standards as far as possible reach. Wood screws with a specially shaped shank for anchoring in the concrete are mainly used for the shear-resistant connection of existing wooden ceilings with a concrete slab arranged or formed thereon, in particular a concrete slab or in-situ concrete slab, which are referred to as composite anchors or compound screws. Specifically, the chemical anchors are screwed into the wooden ceiling at an angle of 45°, for example, with a screw shank with a wood thread formed on it, so that an upper concrete shank area used for anchoring in the concrete layer protrudes beyond the wooden ceiling. Then a topping of approx. 6 to 10 cm thick is applied, in which the concrete shaft area of the chemical anchor is received and anchored, so that after the concrete has hardened, the desired shear-resistant connection between the wooden ceilings and the concrete slab prevents mutual shifting. In the case of a wooden beam ceiling as a wooden ceiling, the chemical anchors are usually only screwed into the wooden beams, namely regularly through a wooden formwork. In the case of wooden ceilings designed as stacked boards, on the other hand, the chemical anchors are preferably screwed into the stacked board.

Especially in connection with monument law or monument protection, there is a need for additions not to falsify a monument and, above all, to be reversible. The principle of reversibility serves the purpose of leaving the historical substance as a carrier of historical or artistic statements as intact as possible. The aim of all conservation measures is therefore to counteract the decay of the monument substance without changing it significantly. Interventions in the existing monument always also mean changing it and must therefore be limited to what is absolutely necessary while preserving the authenticity of the monument, in particular its historicity and age value. Construction measures are therefore to be seen from the point of view of maintaining the substance and are therefore preferably carried out in such a way that the original condition can be restored at any time, i.e. the historical building structure is not damaged after the demolition. This is not possible with wood composite ceilings, because although the concrete slab can be removed relatively easily, a screw channel always remains when removing the chemical anchors, which is considered damage to the historical building fabric and, from a legal point of view, a defect that may lead to claims for damages. The damage to the listed wooden ceiling is all the greater if, as is often the case, the chemical anchors are set with the help of a pre-drilled hole or if, as is also regularly the case, the chemical anchors break off when unscrewed and thus remain in the screw channel. In the latter case, it may also be necessary to cut the broken screw shanks out of the wood, which leads to even greater damage.

It is therefore the object of the invention to provide a method for treating wooden ceilings in buildings, in particular for treating listed wooden ceilings in buildings, by means of which composite wood ceilings can be produced in a simple manner and dismantled essentially non-destructively.

This problem is solved with the features of claim 1.

Claim 1 relates to a method for treating wooden ceilings, in which a plurality of spaced-apart chemical anchors are first screwed into a wooden ceiling of a building. The chemical anchors are only partially screwed into the wooden ceiling and a screw protruding area protrudes from the wooden ceiling. Then an in-situ concrete and/or topping is applied to the wooden ceiling in such a way that the screw protruding areas of the chemical anchors are anchored in a concrete slab that is then formed after the in-situ or topping concrete has hardened and a composite wood ceiling is produced as a shear-resistant connection between the wooden ceiling and the concrete slab . According to the invention, it is provided that the chemical anchors are screwed into the wooden ceiling without pre-drilling or without pre-drilling. For the reversible and/or non-destructive demolition of the composite wood ceiling, the concrete slab is removed again and the chemical anchors are then removed from the wooden ceiling, with a screw channel remaining in the wooden ceiling. Next, a wood-swelling medium, in particular water or steam, is introduced into the screw channel, so that the material displaced by the respective compound anchor (since no wood chip removal takes place) and/or the screw ca nal surrounding and / or forming wood swells and essentially fills and / or closes the screw channel.

With such a method, on the one hand, a desired shear-resistant connection between the wooden ceiling and the concrete slab can be produced, and on the other hand, a non-destructive dismantling of the composite wood ceiling can be guaranteed, since the sealing of the screw channel by means of the wood-swelling medium has the effect that no screw channels that are considered damage in the area of the wooden ceiling remain. In this way, the reversibility requirements in accordance with monument law can be fully met and damage to the historic building can be avoided. In short, additions to monuments are possible that constitute the monument's value, but do not destroy it.

The wooden ceiling itself can be a wooden beam ceiling having a wooden beam layer, the chemical anchors being screwed at least into the wooden beams of the wooden beam layer. Alternatively, the wooden ceiling can also be a stacked board ceiling having a stacked board, in which case the composite anchors are then preferably screwed at least into the stacked board of the stacked board ceiling.

Preferably, at least one row of shear connectors extending in a defined direction and spaced apart from one another in the direction of extent is provided, preferably such that the at least one row of shear connectors extends along at least one wooden beam of the wooden beam ceiling. The same applies, of course, in connection with a stacked board ceiling. The particular advantage of such a row arrangement is that the concrete slab can be incised or cut through along the row of chemical anchors according to a particularly preferred method so that the concrete slab parts provided with chemical anchors are formed in strips. Because for the non-destructive demolition of the wood composite ceiling, it is preferably provided that the concrete slab is divided by means of a cutting device, for example by means of a floor cutter (wet or dry), and in particular is divided in such a way that both concrete slab parts without composite anchors and concrete slab parts provided with composite anchors are produced. While the concrete slab parts without chemical anchors can be easily lifted from the wooden ceiling, the concrete slab parts provided with chemical anchors must be treated with an impact device, for example a hammer (sledge hammer and/or rotary hammer), in order to free the chemical anchors so that they are exposed. These exposed chemical anchors are then preferably screwed out of the wooden ceiling using a screwdriver.

According to a particularly preferred procedure, it is provided that the screw channel is filled with the wood-swelling medium from the bottom of the screw channel. This filling from the base of the screw channel ensures a functionally reliable, reliable sealing of the entire screw channel. If, on the other hand, the screw channel is filled from the side where the screw channel opens out or from the top side of the screw channel, areas may form in which the wood does not swell or does not swell sufficiently to fill the screw channel.

In principle, the wood-swelling medium can be introduced into the screw channel using any suitable device. However, an embodiment in which the wood-swelling medium is injected from the base of the screw channel into the screw channel by means of a cannula that can be inserted into the screw channel is particularly preferred. The term "cannula" is to be understood in a broad sense and includes any hollow needle arrangement or hose arrangement by means of which the wood-swelling medium can be introduced or injected into the screw channel.

It has proven to be particularly advantageous if the cannula is pulled out of the screw channel during the injection process, preferably essentially continuously. In this way, a particularly functionally reliable and complete closure or filling of the screw channel can be ensured.

In principle, any suitable wood-swelling medium can also be used. As the inventor's tests have shown, excellent results can be achieved with conventional water, which is a natural substance. It is particularly advantageous to use hot water, most preferably water at a temperature of more than 40°, or else steam. The increased temperature of the wood-swelling medium or, in the preferred embodiment, the water causes the water to diffuse more quickly into the wood surrounding or forming the screw channel and thus causes the wood to swell more quickly in the area of the screw channel in order to fill or close it.

• Bevorzugt wird ein, auch als Verbundschraube bezeichneter, Verbundanker vorgesehen, der einen Schraubenschaft mit einem endseitigen Werkzeugansatz, zum Beispiel einen Schraubenkopf, aufweist, an den sich in Schraubenschaftlängsrichtung gesehen zum gegenüberliegenden Ende hin in dieser Reihenfolge ein im montierten Zustand im Beton verankerbarer oberer Betonschaftbereich und ein im montierten Zustand im Holz verankerbarer unterer Holzschaftbereich anschließt, wobei der Holzschaftbereich wenigstens bereichsweise mit einem durch Kaltverformung, insbesondere durch Aufrollen,
• hergestellten Holzgewinde versehen ist. Gegebenenfalls kann auch der obere Betonschaftbereich wenigstens bereichsweise kaltverformt sein und eine erhabene Struktur, zum Beispiel eine Gewindestruktur, aufweisen. Weiter ist vorgesehen, dass der Verbundanker bzw. der den Verbundanker ausbildende Schraubenschaft ungehärtet ist, so dass der Verbundanker eine hohe Duktilität aufweist. Vorteilhaft weist der das Holzgewinde aufweisende kaltverformte und ungehärtete Holzschaftbereich eine Zugtragfähigkeit auf, die maximal 0,5 kN bis 10,0 kN, bevorzugt 1,0 bis 8,0 kN größer ist als die Zugtragfähigkeit dieses kaltverformten ungehärteten Holzschaftbereichs in Einschraubhölzern mit einer Holz-Rohdichte von 310kg/m³ bis 500kg/m³, bevorzugt von in etwa 350kg/m³, sowie bevorzugt bezogen auf einen Einschraubwinkel im Einschraubholz von 20 bis 90 Grad, bevorzugt von 40 bis 50 Grad, insbesondere von 45 Grad.

As the experiments carried out by the inventors have further shown, the method according to the invention can in principle be used with any shear connector that is customary in practice. However, a compound anchor that has a particularly high has ductility. Such a chemical anchor is described in more detail below:

• A composite anchor, also referred to as a composite screw, is preferably provided, which has a screw shank with a tool attachment at the end, for example a screw head, to which, seen in the longitudinal direction of the screw shank, an upper concrete shank area and a lower wooden stock area that can be anchored in the wood when assembled, the wooden stock area being at least partially covered with a
• manufactured wood thread is provided. If necessary, the upper concrete shaft area can also be cold-formed at least in areas and have a raised structure, for example a thread structure. It is further provided that the composite anchor or the screw shank forming the composite anchor is unhardened, so that the composite anchor has a high ductility. Advantageously, the cold-formed and unhardened wood stock area that has the wood thread has a tensile strength that is at most 0.5 kN to 10.0 kN, preferably 1.0 to 8.0 kN, greater than the tensile strength of this cold-formed, unhardened wood stock area in screw-in woods with a wood Bulk density of 310 kg/m ³ to 500 kg/m ³ , preferably around 350 kg/m ³ , and preferably based on a screw-in angle in the screw-in wood of 20 to 90 degrees, preferably 40 to 50 degrees, in particular 45 degrees.

• Während nämlich die gehärteten Verbundanker eine solche Zugtragfähigkeit aufweisen, die in einem erheblichen Maße über deren Zugtragfähigkeit in den Einschraubhölzern liegt, das heißt die Verbundanker also völlig überdimensioniert sind, wird mit dem hier bevorzugt vorgesehenen Verbundanker eine Verbundelement für ein als Holzverbunddecke ausgebildetes Holz-Beton-Tragwerk zur Verfügung gestellt, der mit hinreichender Genauigkeit den Anforderungen an die Zugtragfähigkeit in den gängigen Einschraubhölzern genügt und damit die Ausbildung einer schubfesten Verbindung von Holzdecken mit Betonschichten auf eine wirtschaftliche und preiswertere Art und Weise ermöglicht.

A number of advantages can be achieved with such an unhardened chemical anchor:

• While the hardened composite anchors have such a tensile strength that is significantly higher than their tensile strength in the screw-in timbers, i.e. the composite anchors are completely oversized, the composite anchor that is preferably provided here is a composite element for a wood-concrete floor designed as a wood composite ceiling. Support structure made available, which satisfies the requirements for tensile strength in the common screw-in timbers with sufficient accuracy and thus enables the formation of a shear-resistant connection of wooden ceilings with concrete layers in an economical and cheaper way.

In addition, a composite anchor that has a much higher ductility than a hardened screw shank tends to tear off in practical use much less than the hardened composite anchors, which tend to brittle fracture relatively easily due to their hardened state.

The cold-formed, unhardened wood shank area should preferably have a tensile strength that is greater than the tensile strength of the screw shank before cold forming, preferably 10% to 20% greater than the tensile strength of the screw shank before cold forming, preferably in each case based on a strength of the steel base material of at least 580 N/mm ² .

It is also advantageous if the cold-formed, unhardened wooden stock area has a tensile strength of 16.0 kN to 18.0 kN, most preferably 16.5 kN to 16.8 kN, and this preferably with a strength of the steel base material of at least 580N/mm ² . The tensile strength is measured here up to yielding. Such a tensile strength of the cold-formed, unhardened wooden shank area is particularly advantageous if the screw shank or the wooden shank area has a maximum tensile strength of 15.5 kN, preferably from 11.5 kN to 15.5 kN, most preferably 12.5, before cold forming kN to 15.4 kN, and preferably with a strength of the steel base material of at least 580N/mm ² . Here, too, the tensile strength is again measured up to yielding. The main advantage of a composite anchor designed in this way for composite wood ceilings is that the strength of the screw shank after cold forming is only increased by a maximum of 10% to 30%, preferably by a maximum of 10% to 20%, compared to that before cold forming, which is increased overall has an advantageous effect on the ductility of the screw and also enables economical production.

Furthermore, the cold-formed, unhardened wooden shaft area in the screw-in wood preferably has a tensile strength of 10.0 kN to 15.5 kN, preferably with an anchoring length in the screw-in wood of 100 mm to 140 mm, in particular from 115 mm to 125 mm and most preferably from in about 120 mm. The tensile strength is measured here up to tearing.

The twisting off torque of the shear connector is preferably at least 11 Nm and/or at most 19 Nm, so that the shear connector has a sufficiently high security against twisting.

The screwing resistance of the composite anchor into the screw-in wood is preferably at least 7.0 Nm and/or at most 9.0 Nm. Such a one Screwing resistance thus enables an advantageous, comfortable screwing in of a chemical anchor with little effort.

A major advantage of such a chemical anchor is in particular that it not only does not break when it is bent and then bent back, but also has a residual tensile load-bearing capacity that is completely sufficient for practical use in a composite wood ceiling. As the experiments carried out by the inventors have shown, the tensile strength of the shear connector after bending or bending the unhardened upper concrete shaft area relative to the cold-formed, unhardened wooden shaft area and subsequent bending back of the unhardened upper concrete shaft area in the direction of the screw axis is at least 80% of the tensile strength before bending and rebending. In particular, the tensile strength after bending and bending back is at least 10 kN, preferably at least 11 kN, most preferably around 11 kN to 16 kN.

Compound anchors are particularly advantageous in which the cold-formed, unhardened wooden shaft area has a core thread diameter of 5.3 mm to 5.8 mm and a nominal thread diameter or an outer thread diameter of 8.0 mm to 8.5 mm. A very good desired load capacity of the chemical anchor can be achieved with such a relatively deeply rolled out thread. Excellent tensile strength has also been achieved with a flank angle of the two thread flanks starting from the flank tip of 30 degrees to 35 degrees and/or with a thread pitch of 3.0 mm to 3.5 mm.

According to a further particularly preferred embodiment, it is proposed that the unhardened concrete shaft area, at least in the transition area to the cold-formed, unhardened wooden shaft area, but preferably over its entire length, is thicker, in particular with a larger shaft diameter, than a shaft area of the cold-formed, unhardened wooden shaft area that defines the core diameter of the thread. This unhardened concrete shaft area is preferably conically tapered in the transition area to the cold-formed, unhardened wooden shaft area. With such a structure, step or edge-like jumps in diameter are avoided and a smooth transition is thus created, so that an undesired notch effect in this area can be reliably avoided. Furthermore, in an advantageous dual function, this conically tapered transitional area can also be used during the screwing-in process to indicate to the worker that the end of the wood thread has been reached and the screwing-in process can be ended.

According to a further optional embodiment, the unhardened concrete shaft area can also be provided with a raised surface structure in order to increase the anchoring of the shear connector in the concrete, if necessary. The raised surface structure can extend over at least a partial area of the unhardened concrete shank area and be formed, for example, by a concrete shank thread that is preferably cold-formed. Particularly preferred in this context is a concrete shank thread that merges into the wood thread in the transition area between the unhardened concrete shank area and the unhardened, cold-formed wooden shank area, because this reliably prevents a notch-like material weakening at the transition between the threaded areas in a functionally reliable manner. These measures, albeit small, also advantageously serve to increase the tensile strength of the shear connector overall and, above all, to increase its tearing and tearing strength.

Particularly preferably, the concrete shank thread can have thread flanks which, in relation to the longitudinal direction of the shank, drop away from the flank tip towards both sides of the flank tip at a shallow angle of 100 degrees to 150 degrees, preferably of around 120 degrees, against the longitudinal axis of the shank, and although preferably with a thread pitch of at least 5.0 mm.

In the transition area of the tool attachment designed as a screw head to the unhardened concrete shank area, the screw shank can also be made thicker, in particular with a larger shank diameter, than an adjoining shank area of the unhardened concrete shank area. For example, this transition area can in turn taper conically in order to implement a soft, flowing transition to the unhardened concrete shaft area. In this way, a high tear-off strength is also achieved in the area of the highly stressed tool attachment.

Exemplary embodiments of the solution according to the invention are explained in more detail below with the aid of several drawings.

• 1 schematisch eine beispielhafte Ausführungsform eines bevorzugten Verbundankers für eine Holzverbunddecke,
• 2 eine beispielhafte Anordnung mehrerer in der 1 dargestellter Verbundanker in einer Holzverbunddecke,
• 3 schematisch den ersten Schritt des Rückbaus der Holzverbunddecke, bei dem die Betonplatte mittels einer Schneidvorrichtung zerteilt wird,
• 4 das Abheben der verbundankerfreien Betonplattenteile,
• 5 das Freischlagen der Verbundanker mittels eines hier beispielhaft verwendeten Bohrhammers,
• 6 das Herausdrehen der freiliegenden Verbundanker aus der Holzdecke,
• 7 eine schematische, vergrößerte Detailansicht eines freigelegten Verbundankers,
• 8 eine Darstellung gemäß 7 mit herausgedrehtem Verbundanker und verbleibendem hohlen Schraubkanal,
• 9 das Einführen einer Kanüle in den Schraubkanal und das Einbringen von heißem Wasser zum Aufquellen des Holzes im Bereich des Schraubkanals, und
• 10 den aufgequillten und verschlossenen Schraubkanal.

Show it:

• 1 schematically an exemplary embodiment of a preferred composite anchor for a wood composite ceiling,
• 2 an exemplary arrangement of several in the 1 illustrated bond anchor in a wood composite ceiling,
• 3 Schematic of the first step in dismantling the wood composite ceiling, in which the concrete slab is divided using a cutting device,
• 4 the lifting of the anchor-free concrete slab parts,
• 5 knocking free the chemical anchors using a hammer drill used here as an example,
• 6 unscrewing the exposed chemical anchors from the wooden ceiling,
• 7 a schematic, enlarged detail view of an exposed shear connector,
• 8th a representation according to 7 with screwed-out chemical anchor and remaining hollow screw channel,
• 9 inserting a cannula into the screw channel and introducing hot water to swell the wood in the area of the screw channel, and
• 10 the swollen and closed screw channel.

In the 1 is a schematic and exemplary embodiment of a preferred composite anchor 1 for an example in the 2 illustrated wood composite ceiling 2 shown.

This composite anchor 1 consists of a screw shank 3 made of a steel base material, which has a strength of, for example, 580 N/mm ² prior to the cold forming described in more detail below to form a wood thread. This screw shank 3 has a screw head 4 as a tool attachment at the end, which is provided here, merely by way of example, with an outer polygon and an inner Allen key attachment. Of course, other geometries are also possible. Seen in the longitudinal direction of the screw head, this screw head 4 is joined to the opposite, “pointed” end in this order in the assembled state ( 2 ) in a concrete layer or concrete slab 5 anchorable upper concrete shaft area 6 and in the assembled state in the wood ( 2 : wooden beam ceiling 7) anchorable lower wooden shaft area 8, whereby the wooden shaft area 8 is provided here with a wooden thread 9 produced by cold forming, for example by rolling out.

The entire screw shank 3 and thus the entire shear connector 1 is unhardened.

For example, the cold-formed, unhardened wooden shaft area has a thread core diameter of 5.8 mm and a nominal thread diameter or thread outer diameter of 8.5 mm, with a flank angle measured away from the flank tip and related to the two adjacent thread flanks of 30 degrees or an exemplary thread pitch of 3.2 mm.

The unhardened concrete shaft area 6 is thicker or has a larger shaft diameter in the transition area 10 to the cold-formed, unhardened wooden shaft area 8, as shown, than the shaft area of the cold-formed, unhardened wooden shaft area 8 that defines the core diameter of the thread, with this unhardened concrete shaft area 6 in the transition area 10 to the cold-formed, unhardened Wooden shaft area 8 tapers conically and thus a soft, flowing transition between the wooden shaft area 8 and the concrete shaft area 6 is created.

The unhardened concrete shank area 6 is also provided with a raised surface structure here, for example with a concrete shank thread 11 which merges directly into the wood thread 9 in the transition area 10 . This surface structure or specifically the concrete shank thread 11 is preferably a thread produced by cold forming, the thread flanks of the concrete shank thread 11 falling away from the flank tip at a flat angle relative to the longitudinal direction of the shank towards both sides of the flank tip. The gently sloping thread flanks enclose a drop angle of 120 degrees.

The thread pitch of the concrete shaft thread is 6 mm here, for example, with a core diameter of 7.4 mm and a nominal or external thread diameter of 9 mm.

In the transition area 12 from the screw head 4 to the unhardened concrete shank area 6, the screw shank 3 is also thicker or has a larger shank diameter than the adjoining shank area of the unhardened concrete shank area 6, with this transition area 12 again preferably being conically tapered here.

The shear connector 1 shown here as an example has a tensile strength of 16.7 kN in the cold-formed, unhardened wood shaft area, for example, and a tensile strength in screw-in wood with a wood bulk density of preferably around 350 kg/m ³ , based on a screw-in angle of 45 degrees (see 2 ), a tensile strength of 14.5 kN. This, for example, based on an anchoring length of 120 mm in the screw-in wood. This ensures that the tensile strength of the shear connector 1 is greater than the tensile strength or pull-out strength in the screwed wood, so that a functionally reliable Anchoring of the shear connector 1 in wooden beam ceilings 7 is possible.

The wooden beam ceiling 7 in the 2 consists here, for example, of one or more supporting wooden beams 13, which carries a wooden formwork 15 consisting of several wooden boards 14, on which building foils 16 are applied here, merely by way of example. Like in the 2 shown, the chemical anchors 1 are screwed with their cold-formed, unhardened wooden shaft area 8 up to the transition area 10 into the wooden beam ceiling 7, here by way of example at a 45-degree angle, so that the unhardened concrete shaft area 6 projects beyond the wooden beam ceiling 7. Concrete is then poured on to form a concrete slab 5, so that after the concrete has hardened, a correspondingly desired shear-resistant composite wood ceiling 2 is formed as a composite wood-concrete framework. In this hardened state of the concrete, the concrete shaft area 6 is securely accommodated and anchored in the concrete slab 5 .

• So wird zunächst, wie in der 3 schematisch dargestellt, die Betonplatte 5 mittels einer Schneidvorrichtung 17, zum Beispiel mittels eines Nass- oder Trockenfugenschneiders, entlang einer Reihe von Verbundankern 1 so eingeschnitten bzw. durchgeschnitten, dass zum einen verbundankerfreie Betonplattenteile 19 und zum anderen mit Verbundankern 1 versehene Betonplattenteile 18 entstehen.

If now such a wood composite ceiling 2, for example, for reasons of monument protection, are dismantled again, this can be done easily with the method according to the invention, which is described below in connection with the 3 until 10 is explained in more detail:

• So first, as in the 3 shown schematically, the concrete slab 5 is cut or cut through by means of a cutting device 17, for example by means of a wet or dry joint cutter, along a row of shear connectors 1 such that on the one hand concrete slab parts 19 without shear connectors and on the other hand concrete slab parts 18 provided with shear connectors 1 are produced.

As can be seen in particular from the 90° rotated view of the 4 As can be seen (see coordinate system xyz), the concrete slab 5 is incised or cut through to the left and right of the row of chemical anchors 1 in such a way that the concrete slab parts 18 provided with chemical anchors 1 are formed in strips.

Like this from the 4 As can further be seen, the concrete slab parts 19 without composite anchors are then lifted off the wooden beam ceiling 7 with a suitable tool, so that only the strip-like concrete slab parts 18 provided with the composite anchors 1 remain.

These concrete slab parts 18 provided with chemical anchors 1 are then processed by means of an impact device 20, for example by means of a hammer drill, as a result of which the chemical anchors 1 are knocked free and are exposed (see also 6 ). These exposed composite anchors 1 can then be turned out of the wooden beam ceiling 7, for example by means of a screwdriver 21, as is also shown schematically in FIG 6 is shown.

the 7 shows an enlarged, schematic basic representation of a shear connector 1 exposed after the demolition and removal of the concrete slab 5 8th shown, a screw channel 22 in the wooden beam ceiling 7.

According to the teaching of the invention is now, as in the 9 shown, for example a hollow needle or cannula 23 is inserted into the screw channel 22 in such a way that the screw channel 22 is filled from the screw channel base 24 by means of a wood-swelling medium, which is preferably and for example hot water 25 (see 9 ) is. In doing so, the cannula, which is in the 9 indicated by the arrow 26, is pulled out of the screw channel 22 during the injection process, for example essentially continuously, so that the screw channel 22 is filled or wetted with hot water or with the wood-swelling medium essentially along its entire length.

This hot water introduced into the screw channel 22 then causes the wood to swell in the area of the screw channel 22, whereby the screw channel 22, as in FIG 10 shown schematically, is again essentially closed or filled with a wood material.

Reference List

1

chemical anchor

2

wood composite deck

3

screw shank

4

screw head

5

concrete slab

6

upper concrete shaft area

7

wooden beam ceiling

8th

lower wooden shaft area

9

wood thread

10

transition area

11

concrete shaft thread

12

transition area

13

wooden beams

14

wooden boards

15

wooden formwork

16

construction foil

17

cutting device

18

Concrete slab parts (with chemical anchors)

19

Concrete slab parts (free of shear connectors)

20

impact device

21

screwdriver

22

screw channel

23

cannula

24

screw channel reason

25

hot water

26

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Claims (14)

Method for treating wooden ceilings, in which a plurality of spaced-apart shear connectors (1) are first screwed into a wooden ceiling (7) of a building, the shear connectors (1) being screwed into the wooden ceiling (7) only in a partial area and with a Screw protruding area (6) protrudes from the wooden ceiling, with in-situ and/or topping concrete then being applied to the wooden ceiling (7) in such a way that the screw protruding areas (6) of the shear connector (1) after the in-situ and/or topping concrete has hardened are anchored in a concrete slab (5) that is then formed and a composite wood ceiling (2) is produced as a shear-resistant connection between the wooden ceiling (7) and the concrete slab (5), characterized in that the chemical anchors (1) are inserted without pre-drilling or without pre-drilling in the Wood ceiling are screwed in that the concrete slab (5) is removed again for the reversible and / or non-destructive dismantling of the wood composite ceiling (2), that subsequently end the chemical anchors (1) are removed from the wooden ceiling (7), with a screw channel (22) remaining in the wooden ceiling (7), and that a medium (25) that swells the wood, in particular water or steam, is then injected into the screw channel (22 ) is introduced, so that the wood displaced by the respective compound anchor (1) and/or surrounding and/or forming the screw channel (22) swells and essentially fills and/or closes the screw channel (22). procedure after claim 1 , characterized in that the wooden ceiling (7) is a wooden beam ceiling having a wooden beam layer and the shear connectors (1) are screwed at least into the wooden beams (13) of the wooden beam layer or in that the wooden ceiling is a wooden beam ceiling having a stacked board and the shear connectors are at least in screwed into the stacked board of the stacked board ceiling. procedure after claim 1 or 2 , characterized in that at least one row of shear connectors (1) extending in a defined direction and spaced apart from one another in the direction of extension is provided. procedure after claim 2 and 3 , characterized in that the at least one row of shear connectors (1) extends along at least one wooden beam (13) of the wooden beam ceiling. Method according to one of the preceding claims, characterized in that the concrete slab (5) is divided by means of a cutting device (17), in particular by means of a joint cutter, in particular is divided in such a way that both concrete slab parts (19) without composite anchors and concrete slab parts (19) provided with composite anchors 18) arise. procedure after claim 4 and 5 , characterized in that the concrete slab (5) is cut or cut through along the row of shear connectors (1) in such a way that the concrete slab parts (18) provided with shear connectors (1) are formed in strips. procedure after claim 5 or 6 , characterized in that the composite anchor-free concrete slab parts (19) are lifted from the wooden ceiling (7). Procedure according to one of Claims 5 until 7 , characterized in that the concrete slab parts (18) provided with chemical anchors (1) are machined by means of a striking device (20), in particular by means of a hammer, and the chemical anchors (1) are knocked free so that they are exposed. procedure after claim 8 , characterized in that the exposed composite anchors (1) are rotated out of the wooden ceiling (7), preferably by means of a screwdriver (21). Method according to one of the preceding claims, characterized in that the screw channel (22) is filled with the wood-swelling medium (25) from the bottom (24) of the screw channel. procedure after claim 10 , characterized in that the wood-swelling medium (25) is injected into the screw channel (22) from the screw channel base (24) by means of a cannula (23) that can be inserted into the screw channel (22). procedure after claim 11 , characterized in that the cannula (23) is pulled out of the screw channel (22) during the injection process, preferably essentially continuously. Method according to one of the preceding claims, characterized in that the wood-swelling medium (25) is water, preferably hot water, most preferably water hotter than 40°C, or steam. Method according to one of the preceding claims, characterized in that the shear connector (1) has a screw shank (3) with a tool attachment at the end, to which, seen in the longitudinal direction of the screw shank, there is a tool that can be anchored in the concrete (5) in the mounted state towards the opposite end in this order upper concrete shank area (6) as a screw protruding area and a lower wooden shank area (8) that can be anchored in the wood when assembled, the wooden shank area being provided at least in areas with a wooden thread (9) produced by cold forming, the screw shank (3) being unhardened, and that the cold-formed and unhardened wooden shaft area (8) having the wood thread (9) has a tensile strength that is at most 0.5 kN to 10.0 kN greater than the tensile strength of this cold-formed, unhardened wooden shaft area (8) in defined predetermined screw-in woods with a wooden bulk density of 310 kg/ m3 to 500 kg/m3, based on a screw-in angle in the screw-in wood of 20° to 90°, preferably 40° to 50°.

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