FI101692B - Process for making concrete products - Google Patents

Description

, 101692

The present invention relates to a method for producing concrete products with reinforcements by casting at least two products in a row in succession as a continuous piece, the common reinforcements of the products running in the piece in a row and then cutting the piece into products, and - dimensioning the length of the continuous piece so that there is an intermediate between at least two consecutive products; 10 - reinforcements are prestressed before casting; - after casting, before the concrete hardens, concrete is removed from the intermediate part between at least two consecutive products from above the reinforcements to the upper surface of the reinforcements; is - the concrete is allowed to harden further; - tension is released from the casting ends before the reinforcements are cut; - the reinforcements are cut at the point between the ends of at least one intermediate part so that the reinforcement remains protruding from the ends of the finished products 20; - the remaining intermediate concrete is removed.

The object of the invention is to cut the hollow slab so that the tendon braids remain visible in the desired length as adhesions for post-casting.

25 In many areas, especially those prone to earthquakes, building regulations require that hollow core slabs used as intermediate bases be joined together as uniform fields. Likewise, the end of the slab coming to the support must be anchored so that the earthquakes do not cause the slab to fall off the support. This anchoring requires that the ends of the slab can be infected. In a prestressed slab, the adhesion must be applied specifically to the prestressed braids which receive the tensile stress near the lower surface of the slab.

The conventional sliding plate 35 cast on a long base is cut by sawing to the desired length. In this case, the end of the slab is straight and smooth, ie it is difficult to fasten it reliably in case of possible displacement of the support, e.g. in earthquakes.

2 101692

FR 2 211 874 discloses a method for providing adhesions for anchoring from prestressing reinforcements to the end of a slab. The concrete part to be removed is cut fresh from top to bottom using vibrated blades.

5 The lower edges of the blades have notches through which the reinforcements pass in the lower position of the blades. However, when the lower edge of the slab is cut by vibrating while the concrete is still soft, the lower edge of the slab head easily becomes uneven.

DE 2 631 331 describes a method in which the cutting of the reinforcements and the slabs is carried out before the concrete hardens and the ends of the reinforcements are bent inside the slabs. The reinforcements do not protrude from the finished slabs for anchoring.

The basic idea of the present invention is that the above-mentioned grip is best if the prestressing braids are exposed at the ends of the slab so that their ends protrude from the slab. They can then be attached to the support or in a continuous tile to the next slab, for example with additional steels, wedge anchors, etc. and post-casting.

20 The second objective is to keep the lower edge of the slab against the support as straight and intact as possible so that it can withstand the compressive load which may be applied to it.

The method according to the invention is characterized in that the hardened intermediate part (7) between the products (1, 1 ') remaining after cutting the reinforcements (4) is cut by sawing from below the slab.

The method according to the invention provides a concrete product in a simple manner, from the ends of which protrude the ends of the reinforcement 30. These reinforcement ends can be used to connect the concrete product to the support so that it cannot reach. fall off the support. The method according to the invention achieves the highest possible strength and dimensional accuracy of the lower edge of the end of the slab. This fact is of great importance, because it is on this edge that the tile rests on the support.

When the concrete is removed from the intermediate part above the reinforcements before the concrete hardens and the tension of the reinforcement braids is released before the cutting, after the cutting the braid slip can also be seen, ie how well the braids have held 3 101692. If the adhesion does not hold, the braid slides inside the tile somewhat after cutting. Any braid slip can be detected from the length difference between the braid and the lower part of the intermediate part and thus the quality can be controlled.

The invention and its details will be described in more detail below with reference to the accompanying drawings, in which Fig. 1 shows a side view of the products according to the invention immediately after casting, Fig. 2 shows the same after concrete has been removed from the intermediate part and Fig. 3 shows a product according to the invention. after it has been cut from the cast part.

In the method according to the invention, the entire length of the casting vessel 15 is cast in one piece, which can be about 100 to 150 m long. In Figure 1, the desired length of tile 1, 1 'is marked immediately after casting so that always between the end of the previous tile and the beginning of the next tile. twice the portion 2 of length 20 of the desired gripping length a is left unused. Thereafter, the ends of the successive slabs 1, 1 'are sawn before the concrete hardens as fresh sawing, so that the sawing depth 3, 3' extends close to the upper surface of the tendon braids 4.

Next, it can be seen in Fig. 2 that the uncured concrete between the fresh saws 3, 3 '25 has been removed from the top of the casting. . up to level 4 of tendon braids. Concrete can be removed either with a shovel or mechanically. If desired, the removed concrete can be used as a plug 6 for the hollow ends of the slabs with cavities 5.

30 An additional advantage of this removal of concrete is that it avoids shrinkage cracks that normally enter the entire substrate-length curable slab. This is explained by the fact that the shrinkage stresses caused by the hardening of the concrete can be released at the points where the concrete has been removed. 35 The entire casting substrate is then allowed to harden normally until the so-called the tensile strength is reached and the adhesion of the concrete to the tendon braids 4 is sufficient. In this case, the tension of the braids may ·. may be released from the ends of the chassis. Next, the lower part of the slabs 7 4 101692 with its wires 4 is cut from above at points 8 from which the concrete has already been removed above the braids.

The method also has the advantage that the saw blade can be smaller and thus the saw blade lighter and cheaper than when sawing a full-height hardened slab, as is usually done.

Figure 3 shows the next step in which the slab is raised on the sawing device 9. The lower parts 7 of the ends of the slab are sawn from below close to the lower surface of the tendon braids 4 from such points 3 as the upper side was sawn uncured.

Sawing the lower surface 7 only when hardened guarantees the flawlessness of the lower edge of the slab head. Another possibility would be to remove the uncured concrete between the fresh cuts also from under the braids and between the gaps. In this case, however, vibrations are easily caused to the braids, which can impair their adhesion, and in any case the lower edge of the slab head becomes uneven and the already compacted concrete is disturbed.

The remaining concrete part of the intermediate part below the braids 4 is then removed from the actual slab by folding 20, for example by means of a pusher 10 belonging to the sawing device.

Finally, the concrete adhering to the ends of the braids 4, but otherwise already detached from the slab, is removed either by manual hammering or by a suitable crushing device. This provides the ends of the adhesive braids projecting to the ends of the slab, which can be used to attach the slab.

After the process described above, the result is a prestressed hollow core slab with a straight and intact lower edge on the end support and whose tendon braids 4 continue as adhesions of the desired length over the end of the slab.

30 The visible ends of the braids can still be bent as desired, making it easy, for example, to attach cross-steels for post-casting to them. If necessary, wedge anchors, for example, can be attached to the ends of the braids to ensure infection.

The invention is not limited to the application described above, but may vary in various ways within the scope of the claims. The product to be cast need not be from a cavity and the product may be other than a slab. Casting 5 101692 can be performed other than as sliding casting. The reinforcements do not necessarily have to be prestressed.

Claims (1)

A method for producing concrete products (1, 1 ') with reinforcements (4) by casting at least two products in a row in succession as a continuous piece, in which case the common reinforcements of the products run continuously in the piece in the row and the piece is cut into products, and wherein - the length of the continuous body is dimensioned so that an intermediate part 10 (2) is left between at least two successive products (1, 1 '); - the reinforcements (4) are prestressed before casting; - after casting, before the concrete hardens, concrete is removed from the intermediate part (2) between at least two successive products (1, 1 ') from above the reinforcements (4) to the upper surface of the reinforcements 15; - the concrete is allowed to harden further; - tension is released from the casting ends before the reinforcements (4) are cut; - the reinforcements (4) are cut at a point (8) between the ends (3, 3 ') of the at least one intermediate part (2) so that the reinforcement remains protruding from the ends of the finished products (1, 1'); - the remaining concrete (7) of the intermediate part is removed, characterized in that - after cutting the reinforcements (4), the remaining hardened intermediate part (7) between the products (1, 1 ') is cut by sawing from below the slab. 101692 For use in the manufacture of concrete products (1, 1 ') for use in the manufacture of reinforcing products (4) the production of the product and the colors - the dimensions of the contiguous stigket are at least 10 times higher than the value of the product (1, 1 ') or the sample (2); - armeringarna (4) förspänns före gjutningen; - in the case of (2), the ätminstone tvä pä varandra yljande produkterna (1, 1 ') / ovanför armeringarna (4), efter 15 gjutningen avlägsnas betong ända account armeringarnas övre yta; - betongen Fär härdna vidare; genomic gjutstyckets ändor utförs avspänning innan armeringarna (4) bryts av; - an armrest (4) or a point (8) is provided with 20 or more (2) compounds (3, 3 ') / colors according to the conditions of the first product (1, 1'); - resten av betongen (7) i mellandelen avlägsnas, kännetecknat av att - den efter avbrytningen av armeringarna (4) äterstäende 25 härdnade mellandelen (7) mellan produkterna (1, 1 ') skärs av genom att säga underifrän Plattan.