FI62244C - ANORDNING FOER FOERUPPVAERMNING AV BETONG FOERE DESS GJUTNING - Google Patents

Description

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Patent and oct regstterstyrelsan '7 Antdkan utitfd och uti. , 2, rue Louis Murat, 75008 Paris, France-France (FR) (72) James Gaulon, Fontainebleau, France-France (FR) (7M Forssen & Salomaa Oy (5 ^) Device for preheating concrete before pouring - Anordning för föruppvärmning The present invention relates to the preheating of concrete and in particular to a device for preheating concrete just before it is poured.

It is known that it is advantageous to preheat the concrete before pouring it into boards or molds in order to improve its adhesion. Generally, this heating is performed by steam.

It has recently been proposed to heat concrete in a horizontal tank on site just before it is used by means of metal-forming slabs, between which an electric current is conducted with the concrete mass between the electrodes acting as an electrical resistor and thus heating under the Joule effect. In this case, an electric current is passed through the concrete for about ten minutes to bring it to the order of 50 ° C, with the preheated concrete thus being emptied directly into ordinary boards.

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Electric preheating of concrete is very advantageous, as it allows excellent utilization of electrical energy when the kilowatts used are converted in substantially equal yields into calories directly heating the concrete, the temperature of which can rise so rapidly to 50 ° C, as described above. In addition, if the concrete thus preheated to 50 ° C is poured into heat-insulating boards, the removal of the boards can be carried out after a very short time, avoiding heating by mass or boarding, whereby the overall yield is much lower.

Current electric concrete heaters use horizontal concrete tanks that must be raised before casting preheated concrete, but this lifting requires the use of a crane, which can cause lifting and the concrete sticks to the tank, which becomes unusable or has to be refurbished at great cost. In addition, known devices use parallel electrodes which do not obtain homogeneous current densities throughout the concrete mass, resulting in the formation of hot spots and even the danger of causing the water in the concrete to boil, leading to a reduction in the final concrete water content and poor quality.

In addition, DD Patent Publication No. 105,416 discloses an apparatus for preheating concrete mass. This takes place in a tank whose walls are inductively heated by means of windings. The apparatus may also include an inductively heated heating rod. DD Patent Publication No. 92,003 discloses a concrete treatment apparatus for mixing and possibly heated.

The object of the present invention is to eliminate said drawbacks in known devices for preheating concrete before it is ready.

The device according to the invention for preheating concrete before pouring it is characterized in that it has a combination of: at least one vertical concrete container with a preheated concrete inlet at the top and a pourable inlet at the bottom, a movable horizontal plate adapted to close said concrete and a device having a plurality of elongate electrodes attached to the lower surface of said plate vertically suspended from said plate about a vertical central axis, means for vertically displacing said plate with said electrodes to an upper position in which it releases said insertion opening , wherein said electrodes sink into the preheated concrete contained in the concrete container and said insertion opening is closed by said plate, said vertical center axis coming into contact with the vertical axis of the concrete container and means for energizing these electrodes and connecting the concrete tank to ground.

Preferably, the three electrodes are finger-shaped of equal length or different length and closed at the bottom, and preferably have a cross-section in the shape of a hollow circular sector or ellipse.

In a first embodiment of the device, the concrete is preheated before it is poured on the boards at the construction site, in which case it further has a horizontal bridge on which at least one concrete tank of said type is permanently provided with an outlet corresponding to the concrete tank outlet. a horizontal arm capable of reciprocating on a column, the free end of which supports said electrode device, and in a preferred embodiment the bridge supports two concrete containers having two outlets, the horizontal arm of the logs being able not only to reciprocate but also to rotate around the column, to either of the concrete tanks.

According to another embodiment of the device, the concrete is preheated in a plant pouring concrete objects and then in combination with a vertically movable electrode device of the above-mentioned type has a plurality of concrete tanks of the above-mentioned type 4,62424 for recovering and transporting heated concrete to a casting site for said articles.

The device for preheating concrete according to the invention makes it possible to achieve complete homogeneity of the heating of the concrete, since the device arranged for the electrodes provides an excellent distribution of equipotential lines in the concrete mass with an electric field and thus a current density in the concrete mass.

The invention will be well understood in all respects from the following description and the accompanying drawings, which, of course, are presented by way of illustration only.

Figure 1 shows in perspective one embodiment of a device according to the invention for preheating concrete before pouring it on a construction site.

Fig. 2 is a sectional view of the electrode device taken along line II-II of Fig. 1.

Fig. 3 shows a second embodiment of the electrodes in the same way as Fig. 2.

Figure 4 shows the distribution of equipotential lines near an electrode of the type shown in Figures 1 and 2.

Finally, Figure 5 shows a side view of an apparatus according to the invention for preheating concrete in a plant pouring concrete objects in a workshop producing such objects.

Figure 6 is a schematic side view of another electrode device.

Fig. 7 finally shows a section of the electrode device according to Fig. 6.

According to the invention, and in particular to its embodiments and to the embodiments of its various parts, it seems advantageous, for example, to implement a device for preheating concrete in the following or equivalent manner.

Referring to Figures 1-4, an apparatus according to the invention for preheating concrete before pouring it on a construction site will first be described.

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The device is mounted on a horizontal platform or bridge 1. This bridge may support one or more vertical concrete tanks, in particular two concrete tanks, as shown in Figure 1 where one concrete tank (i.e. concrete tank 2) is shown in solid lines and the other (concrete tank 3) schematically dot-dash lines. The net fence 4 surrounds the device to ensure safety when the net fence forms two spaces or booths 5 and 6, each of which has a concrete tank 2 and 3, respectively. is in use and the other is being prepared for use with the reciprocating gate 7 in front of a normally used concrete tank to ensure the safety of workers.

Openings 8,9 are made in the bridge 1, i.e. an opening at 2.3 in each concrete tank. A bracket 10 is placed around each opening 8 or 9 to support the concrete tank 2 or 3.

The concrete containers 2 and 3 have a substantially cylindrical upper part 11a and a conical lower part 11b at the end of the part 11b into an opening 12 which can be closed by a closure 13 operated by a handwheel 13a. Finally, the bracket 15 allows the concrete container 2 with a vertical axis 13v to be moved.

The device for preheating concrete also has, in addition to the concrete tank 2 or 3, an electrode device 14 with three electrodes 15a, 15b and 15c, for example of stainless steel, the arrangement of which is shown in Figure 2. These glove-shaped electrodes (i.e. closed at the lower end) have a hollow circular cross-section the apex angle α is 120 ° in the case of three electrodes, as in the embodiment shown. These electrodes are supported by a circular top plate 16 perforated at the electrodes to allow them to be attached.

The device 14 is supported by a log-like device 17 with a vertical column 18 fixed to the bridge 1 and a horizontal arm 19 which can move back and forth vertically on the column 18 so that the device 14 can be raised or lowered out of the concrete tank 2 or into the concrete tank 3. In addition, two (or more) concrete tanks, such as concrete tanks 2 and 3 mounted on the bridge 1, the same device 17 may serve two concrete tanks with the electrode device 14 common to the two concrete tanks.

6 62244 In this case, the arm 19 can not only move vertically back and forth along the column 18, but it can also turn around this column, so that the device 14 can cooperate with one or the other concrete container.

From an electrical point of view, the electrodes 15a, 15b and 15c are supplied with an electric current, for example 380 volts and 500 amperes by means of a cable 20, while the concrete tank 2 is connected to an earthed electrical zero to ensure the safety of workers.

The device shown in Fig. 1 enables continuous work while the second concrete tank 2 is in operation while the second concrete tank is being prepared for later operation. A preheated concrete is placed in the second concrete tank (tank 2) from the upper opening 21 of this concrete tank, which is released after the device 14 leaves the concrete tank. Then, when the concrete tank 2 is filled, the device 14 is lowered into it and the electrodes 15a, 15b and 15c are fed for five to ten minutes to bring the concrete to a temperature of, for example, about 50 ° C. When this is done, a handwheel is used to move the closure 13 and open the opening 12 of the container 2. The concrete flows through the opening 8 and is recovered by a carriage or cart, which ensures its transport to the desired location or leads it directly to the mold.

When the concrete in the concrete tank 2 is heated, the second concrete tank (tank 3) is filled with concrete. Upon heating of said tank 2, the device 14 is raised by moving the arm 19 vertically, then the arm is rotated to bring the device 14 to the second tank (tank 3), then lowered, and electrodes 15a, 15b and 15c are fed again to ensure heating of the concrete in tank 3. During this time, the concrete is removed from the tank 2, and then it is refilled with concrete.

It is thus found that efficient continuous operation is achieved by emptying and then filling the concrete tank when the concrete in the second tank is heated.

Figure 3 shows the hollow elliptical electrodes 35a, 35b, 35c, which are likewise closed at the lower end like the fingers of a glove, and which can be arranged in place of the electrodes 15a, 15b, 15c of Figures 1 and 2.

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Figure 4 shows the equipotential lines E around the electrode 15a and the 0-center in the third of the plane. Equipotential lines throughout the plane can be easily derived from it. These curves show that the heating of the concrete is very homogeneous.

Referring to Figure 5, an embodiment of an apparatus according to the invention for electrically preheating concrete in an office pouring concrete objects will now be described.

In such a study, for example, beams, tiles, facade pieces and similar profiles and objects made of concrete can be prefabricated. Also in this embodiment, several concrete tanks are provided, for example three concrete tanks A, B and C, of which only two (say concrete tanks C and A at 22 and 23, respectively) are shown in Figure 5, and a single electrode device 24. Concrete tanks A, B and C are shown in Figure 1. of the type indicated by reference numeral 2, while the electrode device 24 may be of the type indicated by reference numeral 14 in Fig. 1 and includes three electrodes 25a, 25b, 25c having a cross section of Fig. 2 (shape of electrodes 15a, 15b, 15c of Fig. 2) or Fig. 3 shape (shape of electrodes 35a, 35b, 35c in this Figure 3).

The device shown in Fig. 5 also has a conveyor 26 provided with a bucket 27, which retrieves the aggregates and cement from a warehouse not shown. The concrete is produced in a mixer 28 of a known type, which obtains the cement and aggregates from the bucket 27 after the conveyor 26 has brought it above the mixer. Instead of the conveyor 26, a belt can be provided for conveying aggregates and cement to the mixer 28. After the concrete has been mixed with the mixer 28, its lower opening 29 is opened and the freshly mixed concrete enters the concrete tank A at 23.

Three concrete tanks (only two of which are shown at 22 and 23) can run along a closed circuit, for example by means of a rail 30.

When the point 23 of the concrete tank A is filled with a mixed concrete, it moves in the direction F to 22, wherein the three concrete container C of Fig while the concrete container C is transferred to a third point, which is not shown, and concrete tank B of the box 23. When the concrete tank A is in place at 22, the electrode device 24 is lowered into this concrete container at 62244 8 22 by means of a pulley 31. Then, within the desired time, an electric current is applied to the electrodes with the concrete tank A connected to ground. When the preheating of the concrete in the concrete tank at 22 has been completed, its lower opening is opened in such a way that, for example, the concrete preheated to 50 ° C can drain into the dividing vehicle 32. When filled, this vehicle is moved towards casting molds or boards, it removes part of its contents by a distribution system comprising an endless belt 34.

It will be seen that in Figure 5, for simplicity, the dispensing vehicle 32 fills the mold 33 already below the concrete container at 22, but generally the vehicle 32 moves from the location shown in Figure 5 to the mold 33 casting location, as described above.

When the lower opening of the concrete container A is closed at 22, it is moved to a third point (not shown) where it can be cleaned, for example, with a jet-type device. During this time, the new concrete tank (tank B) filled at the position 23 shown is moved to the position shown 22. When the concrete in this new concrete tank B at the position 22 is preheated by the electrodes 25a, 25b, 25c, then removed to the dispenser 32, this concrete tank B is taken " under the shower ", while the concrete tank A, which was originally at point 23 and which was under the shower, returns to this point, finally the concrete tank C returns to point 22 shown in Fig. 5.

In order to ensure the entry of each of the three concrete tanks A, B, C under the best possible conditions into three successive points: the filling point (shown in point 23), the preheating and emptying point (shown in point 22) and the cleaning point (not shown), it is advantageous to rigidly tie the three concrete containers. , which rotate on a closed-circuit rail 30, that the automatic positioning at the three workstations is very precise (with one in place the others are automatically), because if the three concrete tanks were independent of each other, the position of each concrete tank at each location should be ensured.

The device shown in Figure 5 enables the automation of the mixing, preheating and preheated concrete pouring phase when the concrete becomes preheated only at the last minute.

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Switching on the heating, i.e. energizing the electrodes 25a, 25b and 25c, can be controlled directly from the vehicle 32, when the driver detects that his ready-to-cast, preheated concrete stock is running low, he connects the concrete to the concrete tank at 22, the heating time is of the order of five minutes, so there is no stock of hot concrete and therefore no losses. Otherwise, the driver can control, for example, lifting the device 24 from the vehicle 7 and moving the concrete containers from one point to the next after emptying the concrete container at point 22, then directing the device 24 to land at the concrete container arriving at point 22 and 23. with concrete from mixer 28. Likewise, the operator can control the operation of the "jet" which cleans the third concrete tank (not shown) at the cleaning point.

It is thus found that the device according to the invention is very well suited for preheating concrete, whether it is intended for use on a construction site for boarding or in a workshop producing concrete objects.

As is clear and as will be apparent from the foregoing, the invention is in no way limited to the more detailed embodiments and embodiments but, on the contrary, includes all modifications.

For example, the electrode device shown in Figures 6 and 7 may be provided with three electrodes 45a, 45b, 45c with two shorter electrodes of greater cross-section and one longer electrode 45c of smaller cross-section. These three electrodes are arranged around the vertical central axis indicated by 0 in Fig. 7, and hang vertically from the plate 16.

In this embodiment, the concrete container 2a is asymmetrical in shape with the outlet opening 12 being eccentric.

This deformation of the electrodes results in a better distribution of electric currents and better heating in the lower part of the concrete tank.

Claims (4)

Apparatus for preheating concrete prior to casting it, characterized in that it has as a combination: at least one concrete container (2; 3) with vertical shaft (13v), the upper part of which in a known manner has an insertion opening (21). ) for concrete to be preheated and the lower part of which has a closable casting opening (12); a movable horizontal plate (16) arranged to close said concrete insertion opening (21) and a device with several relatively long electrodes (15a, 15b, 15c; 35a, 35b, 35c; 45a, 45b, 45c), the lower surface of said disk (16) for hanging in vertical direction from said disk about a vertical center axis (0); means (17, 18, 19) for moving said sheet (16) with said electrodes (15a ... 45c) in a vertical direction between an upper position, whereby it releases said insertion opening (21) to enable filling of said concrete container with concrete to be preheated and a lower position where said electrodes (15a ... 45c) are immersed in the concrete to be preheated in the concrete container (2) and wherein said insertion opening (21) is closed by said disc (16), said vertical center axis (0) will coincide with the vertical axis (13v) of the concrete container (2); and means (20) for feeding these electrodes with Current and for connecting the concrete container to the ground. Device according to claim 1, characterized in that said electrode device has three electrodes (15a, 15b, 15c) which