EP0575457A1 - Injection tube for chemical injection in concrete - Google Patents

Abstract

We describe an injection tube (1) for injecting chemicals into concrete, composed of a central supply tube (2) with regularly spaced perforations (3) and equipped with a sheath (4) arranged so loose on the perforations. Said sheath (4) is constituted by a compressible envelope crossed by pores of small diameter and arranged around the periphery of the tube (2).

Description

Injection tube for chemical injection in concrete.

The present invention relates to an injection tube for chemical injection in concrete.

It is known that concrete structures that stand under water pressure put heavy demands on the construction of the concrete mix in general, and especially stringent require¬ ments must be set for the concrete joints.

The ideal joint between two concrete castings would be one obtained without cracks, crevices, rock nests and the like.

In practice this would be so to speak impossible, however, due to a lack of homogeneity in the concrete and also due to the shrinkage that occurs on setting of the concrete.

An attempt must then be made after the casting to seal the cracks and crevices that have occurred, and one way to accomplish such sealing is by point by point injection into the concrete joints.

This method, however, is unreliable and also very expensive.

Therefore, better methods have been sought for sealing concrete joints, and the process generally used today is an injection system based on perforated tubes running in the longitudinal direction of the concrete joint, where a sealing material — usually a two-component polyurethane material-- is injected into the tubes and distributed into the joint by means of the perforations, with subsequent hardening and sealing.

This system is arranged beforehand, thus obviating the very time-consuming and expensive procedure of drilling through the concrete structure. Known on the market are flexible steel tubes around which are wound one or more layers of textile cloth.

The purpose of the cloth is to prevent the concrete mass being poured from sealing the perforations in the dis¬ tribution tube for the hardening material; but for this purpose, the textile cloth has proven unfavorable, as the cloth is itself a surface element which, during the process of pouring/casting, would become sealed, thus preventing the injection mass from being released from the perforated tube for sealing of the cracks and crevices that had occurred.

Later research and development In this area has led to the system currently being marketed under the trade name "fuko".

This system comprises a tube core of a strong and solid material, along which in the longitudinal direction thereof are disposed grooves, in the bottom of which grooves are in turn formed perforations therethrough.

These grooves are covered by loosely positioned slats, giving the overall profile of the tube an almost circular con¬ figuration.

The purpose of these slats is to prevent the poured/cast concrete mass from sealing the perforations in the tube, while at the same time ensuring that the injection mass can be pressed out of the feed tube and into the surrounding cracks and crevices, even with low pressure.

Finally, this known "fuko" sustem is then provided with a surrounding woven, open plastic stocking to hold the longitudinal slats in place.

This system is technically very reliable and safe in use, but has the drawback that it is relatively complicated to produce and also is very expensive.

The cost therefore justifies its use only in those cases where the concrete structures in question stand under permanent water pressure and must therefore be secured.

In a great many structures, the risk of water pressure outside the concrete structure would be only periodical, and even then is expected only relatively seldom; examples are, for instance, spring flood areas or other more or less periodically but very infrequently flooded regions.

In these cases it would be appropriate to utilize a system that is reasonably safe and reliable in use, but which is simple and easy to produce and is thus also very reasonable to manufacture and to employ.

The present invention aims to provide this type of reasonable injection system for chemical injection in concrete, and therefore relates to an injection tube of the described type comprising a central, regularly perforated feed tube having a cover loosely disposed over the perforation. This tube is characterized in that the cover consists of a compressible casing having fine pores therethrough, and disposed around the periphery of the tube.

This cover preferably consists of a pliable foamed plastic or similar material, having fine through-going pores.

As mentioned above, the purpose of this cover over the perforation is to prevent the sealing of the perforations by the concrete mass poured thereon.

This is achieved by the cover according to the invention by virtue of the fact that the casing, on contact with the concrete, is pressed together and sealed, thereby blocking access of the concrete to the perforations, whereas there will still remain open channels where the effect of the concrete is less direct, enabling the injection mass to be released from the perforations and to flow into the cracks and crevices to be sealed.

As a feed tube there may be used, according to the invention, a conventional thick-walled plastic hose with perforations regularly disposed around the entire circumference.

The casing, when constructed of foamed plastic material, may be produced by extrusion onto the tube.

A surrounding holding stocking may be placed onto the tube, although this is not absolutely necessary.

As material for the cover around the tube, one could also contemplate a densely entangled netting of a wire or fiber product, consisting of filaments having a very fine diameter.

A fine-wired steel wool, for example, could be used.

In this case, it might be advantageous to weave a holding stocking around the outside of the feed tube and the surrounding casing.

The invention is illustrated in the accompanying sketch showing an injection tube 1 consisting of feed tube 2, having in both the longitudinal direction and the circumference thereof regularly positioned perforations 3, and around which central tube 2 there is arranged a compressible casing 4 having fine pores therethrough.

The product according to the invention is simple and easy to produce compared with the prior art, and thus may also be produced for a far lower price than the products of com¬ parable quality currently found on the market. The invention's subject thus meets the market's need for an inexpensive product with reasonable security, for use in all places where waterproofing is necessary due to sporadic risk of water pressure outside the concrete structure, but where the major consideration is, if not to totally shut out the water, at least to delay the seepage of water into the structure to a degree where safety and security is in pro¬ portional to the existing risk.

Claims

P a t e n t C l a i m s

1.

An injection tube (1) for chemical injection in concrete, comprising a central, regularly perforated (3) feed tube (2) having a cover (4) loosely disposed over the perforation, c h a r a c t e r i z e d i n that said cover (4) consists of a compressible casing having fine pores therethrough, arranged around the periphery of the tube (2).

2.

The tube according to claim 1, c h a r a c t e r i z e d in that the cover (4) consists of an elastic foamed plastic or similar material having fine pores therethrough.

3.

The tube according to claim 1, c h a r a c t e r i z e d in that the cover (4) consists of a densely entangled fiber or wire product of filaments having a very fine diameter.

4.

The tube according to claim 3, c h a r a c t e r i z e d in that the wire/fiber product is steel wool.

5.

The tube according to claims 1 and 2, c h a r a c t e r i z e d i n that the tube (2) and cover (4) are formed as a unit and made of the same material.

6.

The tube according to claim 5, c h a r a c t e r i z e d in that the cover has a configuration that provides a contact surface thereon.