EP0684347A2 - Method of producing chemically resistant and liquid impervious expansion joints - Google Patents

Abstract

The prodn. of chemically-resistant expansion joints which are impermeable to liquids comprises cementing a polyolefin foam profile (I) into a concrete, asphalt concrete or poured asphalt joint, using a chemically resistant resin adhesive (II).

Description

The present invention relates to a method for producing expansion joints that are chemical-resistant and liquid-impermeable. The invention also relates to the use of polyolefin foam as a joint tape in the production of such expansion joints.

In systems for storing, filling, handling, manufacturing, treating or using environmentally harmful substances, protective structures, particularly those made of concrete, are used to protect the soil and groundwater. In the event of an unforeseen product leakage, for example from leaked containers, pipelines or production systems, these are required to collect or discharge environmentally hazardous substances. To do this, these structures must be liquid-tight.

However, concrete structures are subject to the effects of temperature and stresses due to subsidence of the subsoil and the shrinking effects of the concrete, which creates forced stresses. This can cause cracks that lead to the permeability of the structure. Such stresses can be reduced if the building is provided with expansion joints, so that deformation of the building is made possible.

In the case of protective structures of the type mentioned above, these expansion joints must be sealed in a chemical-resistant and liquid-impermeable manner without the concrete being able to move.

The sealing of expansion joints is known and z. B. in N. Klawa and A. Haack, "Tiefbaufugen", Ernst and Son Verlag, Berlin, 1990, described. Joint tapes and joint sealants are known. Joint tapes are made of PVC or rubber and are embedded in concrete, pressed into joints or flanged to the concrete. Joint sealants are introduced into the finished joint recesses in the plastic state, bind there and seal the joint by adhesion to the joint flanks. It is important to ensure that the material is only installed at a depth of approx. 0.8 to 1.0 times the joint width (see Industry Association for Sealants, Leaflet No. 1, May 1989 edition). This should ensure that the material has sufficient elasticity; with increasing ratio of joint depth to joint width, this decreases because of the hindrance of the transverse contraction. Mainly polysulfides and polyurethanes are used as materials for joint sealants.

In addition to chemical resistance and impermeability, controllability, interchangeability, mobility and a. U. passability to name.

The materials usually used for joint tapes and joint sealants show only a limited chemical resistance. For example, plasticized PVC (PVC-P) and SBR rubber are only partially resistant to solvents, concentrated acids and oils; The same applies to polyurethanes and polysulfides compared to many solvents such as. B. CHCs, esters, ketones and alcohols as well as oils.

According to the prior art, the joint tapes are embedded or flanged within the component thickness of the concrete structure. The embedded form does not allow for controllability and easy interchangeability. With the flanged construction there is no passability, there is also an increased possibility of damage to the joint tape.

Joint sealing compounds, however, have, as already mentioned, the disadvantage that they can only be installed to a limited depth in relation to the joint width, so that their expansion possibility is retained. With this limited depth, however, it can be expected to be a bit difficult to handle. The liquid penetrates into the concrete and flows around the expansion joint material through the concrete, emerges from the concrete below the joint material and can thus reach the ground. Information on the penetration depths of chemicals in concrete can be found in the "Guideline for Concrete Construction for Handling Water Hazardous Substances, Part 1: Design and Dimensioning of Uncoated Concrete Components" of the German Committee for Reinforced Concrete (DAfStb) from September 1992. You have to choose either with this type of joint accept the disadvantage of a limited possibility of stretching or the risk of being loose and therefore permeable.

The task was therefore to develop a process for the production of expansion joints that have a high chemical resistance, liquid impermeability and mobility. The expansion joints should also be controllable, easy to replace and passable.

Surprisingly, it was found that polyolefin foam not only has a high resistance to chemicals and solvents, but is also able to absorb strains regardless of a hindrance to the transverse contraction of the material. In addition, an easy way was found to connect polyolefin foam with concrete, asphalt concrete or mastic asphalt. The present invention is based on the interaction of these three factors.

The method according to the invention for producing chemical-resistant and liquid-impermeable expansion joints therefore consists in gluing a profile made of a foamed polyolefin into a concrete, asphalt concrete or mastic asphalt joint, using a chemically resistant resin as the adhesive.

Either both joint flanks can consist of one of the materials mentioned above, or there is only one joint flank made of one of these materials and the other joint flank consists of steel.

The requirements for the quality of the concrete are laid down in the "Guideline for Concrete Construction ...", Section 5.1. These requirements are placed on the construction of new plants and determine a water cement value W / Z ≦ 0.50 as an essential criterion. According to a note in section A.2.1 of the above guideline, a concrete with a water cement value W / Z ≦ 0.60 can be assumed for existing systems. The appendix to the directive describes test methods to determine the tightness and resistance of the concrete to chemicals.

The requirements for asphalt concrete and mastic asphalt on floor surfaces that serve to protect the subsurface from water-polluting substances are exemplified in technical rules for flammable liquids, e.g. B. TRBF 111 "Filling, emptying, airfield refueling stations", September 1992 version included. These requirements apply strictly only to flammable, water-polluting substances. An essential feature is a minimum thickness of the top layer of 3 or 4 cm and a void content of less than 3% by volume.

The building materials mentioned are also used for filling and emptying points for rail tank cars. For this reason, the building materials must be connected to the rail profile in a liquid-tight manner in order to be able to conduct escaping liquid through a gradient in collecting facilities. In practice, a gap formation is often found next to the rail profile.

Furthermore, it is frequently found in practice that, with the same height formation of the floor surface with the top edge of the rail, damage occurs alongside the rail through the wheel arch of the track vehicle. This damage is flaking in which leaking liquid can collect. Coupled with the formation of gaps described, the longer residence time of the liquid can lead to penetration of the bottom surface.

The formation of the joint according to the invention between the concrete, asphalt concrete and mastic asphalt surfaces and the steel rail prevents the formation of gaps and prevents damage from the wheel arch due to the elasticity of the material.

In a further embodiment of the present invention, the concrete is coated. This is shown by way of example in FIG. 1.

In this embodiment of the coated concrete (1) , the expansion joint of the concrete is advantageously formed in the applied coating system, wherein the joint profile (2) can be glued in at the same time. The coating system (5) used is state of the art and usually consists of a primer (3) , a tear-resistant layer (5.1) and a chemically resistant layer (5.2) . In order to achieve a tightness, the joint profile is glued to the concrete (1) with the resin of the chemically resistant layer (5.2) in the example shown here, ie the primer (3) and adhesive (4) are identical here. To obtain a sufficiently low viscosity for the primer, the resin can be diluted with a solvent.

Suitable coating systems for concrete that can be used in systems for storing, filling, handling, manufacturing, treating or using water-polluting substances are approved by the German Institute for Building Technology.

These systems, as well as systems that are suitable but not yet approved, have as binders polyurethane (PUR), epoxy resin (EP), unsaturated polyester resin (UP), vinyl ester resin (VE), polymethyl methacrylate (PMMA), furan resin, phenol-formaldehyde resin or Combinations of these resins.

The foamed polyolefin is usually glued into a prepared joint of the more or less hardened concrete. The concrete joint is expediently prepared by cutting non-parallel joint flanks with a concrete cutter with two parallel cutting discs. The foamed polyolefin is then glued into the prepared concrete joint in strips. This procedure has the advantage that it creates a sharp-edged concrete edge.

However, within the scope of the present invention, an immediate installation of the expansion joint profile in a new concrete surface to be created is possible during the concreting process. Here, for example, compression hoses can be installed on each joint flank, through which a suitable resin is pressed after the concrete has hardened in order to obtain a liquid-tight bond.

The term polyolefin here primarily means polyethylene, polypropylene and polybutene-1, the former two being preferred.

In principle, any state-of-the-art foamed polyethylene can be used, regardless of whether it consists of HDPE, LDPE or LLDPE. The material can be uncrosslinked. However, a closed-cell, crosslinked foam is expediently used.

Suitable polypropylenes are, for example, homopolypropylene, ethylene-propylene block copolymers, propylene-ethylene or propylene-butylene random copolymers and random terpolymers of propylene, ethylene and butene-1. Of these, a propylene-ethylene random copolymer with 1 to 15% by weight of ethylene is preferred.

The foamed polyolefin should of course be largely closed-cell. Usually the foam has a density of 15 to 250 kg / m³, preferably from 20 to 100 kg / m³ and particularly preferably from 30 to 60 kg / m³. The production of such foams is state of the art. They can be produced, for example, by extrusion with the addition of a blowing agent, by molding particle foam with the aid of a molding machine or by all other known methods.

Adequate adhesion of conventional adhesive resins to polyolefins is very difficult to achieve because of their non-polar nature. It can be achieved, for example, by exposing the surface to be bonded to a low-pressure plasma, a corona discharge or a strongly oxidizing liquid medium. Another possibility is to produce the foam material from a polyolefin which contains functional groups which have been introduced by grafting or copolymerization in accordance with the prior art. However, a conventional foamed polyolefin is particularly preferably simply primed with a suitable thin-bodied resin. The low-viscosity resin enters the cut cavities, with which mechanical clinging is achieved during the subsequent bonding. In principle, any resin that is sufficiently resistant to chemicals and solvents and that is compatible with the resin used for gluing is suitable. Examples include polyurethane resin (PU), unsaturated polyester resin (UP), epoxy resin (EP), vinyl ester resin (VE), polymethyl methacrylate (PMMA), furan resin (FU) and phenol-formaldehyde resin (PF). Possibly the viscosity can be reduced by adding a suitable solvent.

The pre-coated resin must be hardened or cured before subsequent bonding. As a rough guideline for the curing time, 24 hours at the temperature recommended by the manufacturer for the respective resin (usually at least 50 ° C) should be mentioned.

Resin resistant to chemicals and solvents is also used for bonding. Examples include PU, UP, EP, VE, PMMA, FU and PF. These resins and their properties are known to the person skilled in the art; they are all marketable, so that a more detailed description is not necessary. The resin used for gluing must adhere both to the resin used for the primer and to the concrete of the joint flank.

Installation in a prepared joint is carried out in such a way that the polyolefin foam profile and the concrete flanks are coated with the adhesive. The profile is then inserted by hand. Of course, the installation can also be done mechanically. The joint profile is installed flush with the top edge of the surface and thus serves as formwork for any repairs to broken joint edges.

With a joint width of 2 to 4 cm, the installation depth is advantageously 5 to 15 cm. Of course, if desired, you can also deviate upwards or downwards.

The profiles used can have any desired geometry. Longer joints are provided with a band-shaped profile, which is cut, punched or sawn, for example, from block material measuring 100 x 200 cm in the required thickness. The joint of the joint profiles is made with an oblique cut, for example 45 °. The joint profiles are connected to each other by gluing with a resin of the type that is also suitable for priming. Cross pieces, T-pieces and L-pieces are also sawn, cut or punched from the full block material and also connected by means of bevel cuts by gluing.

With the method according to the invention, expansion joints with high chemical resistance, liquid impermeability and mobility can be produced, which are controllable, easy to replace and can be driven over. The controllability is given by the visibility on the component surface. It is easy to see whether damage or detachment from the joint flanks has occurred. Flank adhesion is easy to check using aids. The leak tightness can be checked with leak detection devices.

The joint tape according to the invention can be replaced without damaging the concrete. The existing expansion joint profile can be easily removed by cutting out the joint material along the joint flanks with cutting, milling or sawing devices. The new material is installed in the joint cut out in this way.

Accessibility is given by the surface flushness. In addition, when the vehicle is run over due to pressures caused by a load, a contact pressure is generated on the concrete edges, which counteracts the edges breaking off.

The invention will be explained below by way of example.

example 1

TROCELLEN® (Hüls Troisdorf AG, D-53839 Troisdorf) was used as the foamed polyethylene. The density of the material was 45 kg / m³; the dimensions of the test specimen were 20 x 5 x 160 mm.

The resistance of this material to various media was tested in a continuous immersion test at room temperature over a period of 72 hours. The results are shown in Table 1.

Corresponding tests on joint tapes made of PVC-P standard quality and SBR are given in N. Klawa and A. Haack, op. Cit., On pages 15 and 19. The comparison shows that joint tapes made of foamed polyethylene are impressively superior to those made of PVC-P or SBR in terms of resistance to chemicals and solvents. Table 1 Results of the 72 h durability test of TROCELLEN® in a continuous immersion test medium Mass change Δ M [%] Volume change (moist) Δ V _f [%] Volume change (dry) Δ V _t [%] evaluation Sulfuric acid 100% 105.1 102.9 91.2 b acetic acid 100.7 102.9 94.1 b n-butanol 98.8 100.4 93.1 b toluene 98.7 117.7 91.2 b Ethyl acetate 98.2 102.7 78.4 b acetone 99.4 100.2 87.8 b Methyl ethyl ketone 99.0 100.0 88.0 b n-butylamine 97.4 95.0 83.8 b Xylene 98.0 120.6 91.2 b n-butyl chloride 98.7 111.8 91.1 b benzene 98.1 102.9 91.2 b Ammonia solution 30% 100.0 103.9 101.3 b Diethyl ether 99.0 119.0 87.0 b b = resistant ub = inconsistent bb = limited resistance

Example 2

• a) Probekörper 1: Zwei Prismen aus Zementmörtel der Abmessungen 3 x 3 x 7 cm³ wurden an den quadratischen Flächen mit einem Schaumkörper der Abmessungen 3 x 3 x 3 cm³ verklebt (Formzahl: 1).
• b) Probekörper 2: Zwei Prismen aus Zementmörtel der Abmessungen 7 x 7 x 7 cm³ wurden mit einem Schaumkörper der Abmessungen 7 x 7 x 3 cm³ über dessen Breitseiten verklebt (Formzahl: 2,33).

This example shows the deformation behavior of TROCELLEN® in comparison with a conventional joint sealant. Two different test specimens were produced:

• a) Test specimen 1: Two prisms made of cement mortar measuring 3 x 3 x 7 cm³ were glued to the square surfaces with a foam body measuring 3 x 3 x 3 cm³ (number of forms: 1).
• b) Test specimen 2: Two prisms made of cement mortar measuring 7 x 7 x 7 cm³ were glued to a foam body measuring 7 x 7 x 3 cm³ across the broad sides (number of forms: 2.33).

Probekörper 1:

$\text{Δb/b = 0,37}$

Probekörper 2:

$\text{Δb/b = 0,40}$

Mit zunehmender Formzahl des Schaumkörpers (d. h., auf die Fuge übertragen, zunehmendem Verhältnis von Einbautiefe zu Fugenbreite) wird also im Rahmen der Meßgenauigkeit zumindest ein konstantes, wenn nicht gar ein verbessertes Dehnungsverhalten gefunden. Bei Verwendung eines konventionellen Fugendichtstoffs wird hingegen gefunden, daß mit zunehmender Formzahl die Dehnung Δb/b stark abnimmt (siehe hierzu N. Klawa und A. Haack, a. a. O., Bild A2/48).These test specimens were subjected to a tensile test, the elongation Δb / b (b = width of the foam body) being measured at the maximum tensile strength. The following values were obtained:

Test specimen 1:

$\text{Δb / b = 0.37}$

Test specimen 2:

$\text{Δb / b = 0.40}$

As the number of shapes of the foam body increases (ie, transferred to the joint, increasing ratio of installation depth to joint width), at least a constant, if not an improved, expansion behavior is found within the scope of the measurement accuracy. When using a conventional joint sealant, on the other hand, it is found that the elongation Δb / b decreases sharply with increasing shape number (see N. Klawa and A. Haack, loc. Cit., Figure A2 / 48).

When using TROCELLEN, there is sufficient freedom of movement even with a large joint depth - which can prevent unpleasantness.

Example 3

The adhesion of TROCELLEN® to the concrete under the influence of media was tested on test specimens. For this purpose, prisms were made from cement mortar measuring 4 x 4 x 7 cm³. At the same time, foam bodies measuring 4 x 4 x 1.2 cm³ were sawn out of a block and provided with a primer on the broad sides, as shown in Table 2. After curing for around 24 hours at room temperature, the foam body was installed between the mortar prisms. The procedure was such that the resin shown in Table 3 applied to both the surfaces of the joint flanks and the pre-painted surfaces of the Foam body was painted. The curing time was 3 days at room temperature. The test specimens were then immersed in the test media specified in Table 4 at room temperature for 72 hours. The tensile strength and the elongation at break were then determined in a tensile test based on DIN 52 455 T1 (feed rate 10 mm / min). The fracture pattern of the broken sample was assessed by means of a percentage description of the remaining adherence. The results are shown in Table 4. Table 2 Primer for the foamed TROCELLEN® component Mass parts MT A Rütapox resin 0166 / S 700 100 Epoxy resin Xylene 40 Rütapox hardener H 90 20.5 B VESTOPAL 400 100 Polyester resin Styrene 13.6 Cumene hydroperoxide 7.8 Co-accelerator 6.9 C. MC-DUR 1000 EM / A resin 100 Epoxy resin Harder 25th Bonding resins for expansion joint material Material designation D MC-DUR 1000 EM / A resin (100 MT) with hardener (25 MT) E Rütapox 0166 / S700 (100 MT) with hardener H 90 (20.5 MT) F *) MC-DUR 3000 VE resin (98 MT) with hardener (2 MT) *) modified polyester resin

β_Z =

Reißspannung

ε_Br =

Reißdehnung

B =

Beton

H =

Harz

PE =

Polyethylen

BH =

Grenzfläche Beton/Harz

HPE =

Grenzfläche Harz/Polyethylen

Explanations to Table 4:

β _Z =

Tensile stress

ε _Br =

Elongation at break

B =

concrete

H =

resin

PE =

Polyethylene

BH =

Concrete / resin interface

HPE =

Resin / polyethylene interface

Claims (12)

Process for producing chemical-resistant and liquid-impermeable expansion joints,
characterized,
that a profile made of a foamed polyolefin is glued into a concrete, asphalt concrete or mastic asphalt joint, a chemically resistant resin being used as the adhesive. Method according to claim 1,
characterized,
that one of the two joint flanks is made of steel. Method according to one of claims 1 or 2,
characterized,
that the concrete is coated. Method according to one of claims 1 to 3,
characterized,
that the profile of a foamed polyolefin is glued into a prepared joint. Method according to one of claims 1 to 3,
characterized,
that the profile is installed in a new concrete surface to be created during the concreting process. Method according to one of claims 4 or 5,
characterized,
that the profile is primed with a resin that is sufficiently resistant to chemicals and solvents. Method according to claim 6,
characterized,
that the resin used for the primer is a polyurethane resin, an unsaturated polyester resin, an epoxy resin, a vinyl ester resin, polymethyl methacrylate, a furan resin or a phenol-formaldehyde resin. Method according to one of claims 1 to 7,
characterized,
that the adhesive is a polyurethane resin, an unsaturated polyester resin, an epoxy resin, a vinyl ester resin, polymethyl methacrylate, a furan resin or a phenol-formaldehyde resin. Method according to one of claims 1 to 8,
characterized,
that the profile made of a foamed polyolefin is a tape, a cross part, a T-piece or an L-piece. Method according to one of claims 1 to 9,
characterized,
that the joint of the joint profiles is produced by an oblique cut, the joint profiles being connected to one another by gluing with a resin which is sufficiently resistant to chemicals and solvents. Method according to one of claims 1 to 10,
characterized,
that the foamed polyolefin is a polyethylene or a polypropylene. Use of a profile made of a polyolefin foam as a joint tape for the production of chemical-resistant and liquid-impermeable expansion joints in concrete, asphalt concrete or mastic asphalt surfaces or between one of these materials and steel.

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