EP3640407B1 - Impregnated fabric with additives - Google Patents

Description

The invention relates to a method for producing a textile reinforcement from a scrim, wherein an impregnation is applied to a thread or a strand of the scrim or to the scrim. Furthermore, the invention relates to such a textile reinforcement.

Structures made of reinforced concrete are an integral part of the infrastructure in almost every country in the world. In addition to residential and work buildings, many structures that are used for traffic are also made of reinforced concrete, e.g. parking garages, garages, highways, bridges, tunnels, etc. A large number of these structures are used for 50 to 100 years (and sometimes even longer). However, in addition to mechanical stress, de-icing salts are particularly damaging to reinforced concrete structures. The de-icing salts usually contain chloride. When combined with water, solutions are created that trigger corrosion in the structures. In many buildings, substantial, cost-intensive repair work has to be carried out on the reinforcement after just 20-25 years.

For this purpose, the contaminated covering concrete is usually removed, the reinforcing steel is cleaned and provided with new corrosion protection (e.g. based on polymer or cement). However, the repaired area often only lasts a few years (due to mechanical, thermal and/or hygric incompatibilities), so further repairs are required as soon as possible, especially if the covering concrete is subject to heavy loads. This causes high costs, represents a significant intervention in the structure and, last but not least, leads to restrictions in use during repairs.

One way to suppress and ideally prevent corrosion is cathodic corrosion protection (KKS) of buildings. Cathodic corrosion protection wins as a largely non-destructive repair method is becoming increasingly important as an economical repair method for components at risk of or damaged by corrosion.

Particularly in the case of reinforced concrete structures that are subject to traffic, in addition to corrosion protection and due to a constantly increasing volume of traffic and increasingly heavier vehicles (trucks, SUVs), many structures that are subject to traffic (bridges, parking structures) must be subsequently reinforced. There are a variety of procedures here, such as: E.g. prestressing with external tendons, shear force reinforcement with tendons or shear plates made of steel, concrete topping with dowelling, cross-sectional additions using shotcrete with additional reinforcing steel reinforcement and (slotted) glued CFRP (steel) lamellas.

To date, however, there is no known process that provides long-term protection for reinforced concrete structures exposed to the weather and traffic from steel corrosion and at the same time provides mechanical reinforcement for the structure. Although composite materials made of carbon concrete or other textile concretes made of basalt or AR glass fibers are increasingly being used and are soaked in an epoxy resin or styrene-butadiene rubber, their possible uses have so far been limited, as they are only used for interior buildings, for example where weather-related influences hardly occur, are suitable or they lack the freedom of form that is often necessary.

Previous textile carbon reinforcements only fulfill the function of structural reinforcement or corrosion protection. However, there are already approaches to soaking the carbon fibers in epoxy resin or styrene-butadiene rubber in order to obtain a stable fabric. Fabrics with epoxy resin impregnation have a high bond strength. Fabrics with styrene-butadiene rubber, on the other hand, are characterized in particular by their good processability, formability and, in particular, sufficient polarization properties. However, there is currently no impregnation that has a pronounced mechanical bond and at the same time good processability/formability and advantageous polarization properties.

Previously soaked textile reinforcements also have in common that laying around corners and edges, or at acute angles and narrow radii of curvature (e.g. transition from floor to column) is very difficult. The poor flexibility of the textile reinforcement or the creation of defects due to narrow radii of curvature means that the reinforcement and corrosion protection effects are not achieved as required.

CA 2 192 567 C shows a method for producing textile reinforcement according to the preamble of claim 1.

The invention is therefore based on the object of specifying a method for producing a textile reinforcement and a textile reinforcement which enables mechanical reinforcement for structures exposed to the weather and traffic and is easy to lay.

The textile reinforcement can also include glass, for example. If cathodic corrosion protection is also possible as part of the mechanical reinforcement, the use of a carbon fabric or a fabric that is at least partially made of carbon fibers is recommended.

In the context of this application, scrim is understood to mean a flat structure which consists of several layers of essentially parallel stretched threads. The individual layers are placed on top of each other and fixed together at the intersection points. If the threads of different layers are aligned in two different directions, this is called a biaxial fabric. If several layers with multiple orientations are provided, this is called a multiaxial fabric. In the context of this application, the term scrim also means a grid which also has a corresponding structure.

The thread of a scrim is understood to be a single stretched strand. This thread can consist of a number of carbon multifilaments, which together form a thread or strand.

This object is achieved according to the invention in that the impregnation comprises a base material to which an additive is added.

The invention is based on the idea that the provision of sufficient mechanical reinforcement and, if necessary, sufficiently high conductivity for cathodic corrosion protection can be achieved by suitable selection of an impregnation medium. It has been shown that the fabric of the textile reinforcement can be particularly easily adapted to the specific requirements at the site of use if the impregnation and the base medium used for the impregnation are modified by adding additives to increase the electrical, mechanical and thermal properties. For example, it is possible to increase the electrical properties, in particular the conductivity, by adding carbon nanotubes, metal particles, salts (or ionic compounds) or graphite, while the thermal properties can be increased by adding metals, carbon and Graphite particles can be influenced. To improve the mechanical properties, especially the bond with the solid mortar, it is possible to add hard materials, for example in the form of silicon carbite, quartz and ceramics.

Furthermore, it is possible to modify the process parameters and possible processability of the fabric, in particular a carbon fabric, by adding the additives. It is conceivable to use plasticizers, retarders or swelling agents to influence the properties of the fresh and solid mortar.

In particular, the addition of additives can ensure that the strength of the mortar is particularly high in the area of the scrim, while it is comparatively low on the surface. This strength gradient, which slopes away from the scrim, enables particularly flexible use of the scrim.

For a particularly flexible and diverse possibility of modification, the base material is preferably made by radical polymerization a monomer and a starter synthesized. It is now possible to add the additive to the monomer and/or the starter before synthesis. This allows the impregnation to be modified before the base material is synthesized. Additionally or alternatively, it is also possible to add the additive to the already synthesized base material before, during the impregnation and/or after the impregnation in the form of sprinkling onto the impregnated fabric.

In a special form of impregnation or as part of the later coating, the starter is applied to the fabric in a first process and then the monomer is applied so that the base material is synthesized directly on the fabric.

The use of a polymethyl methacrylate as a base material for the impregnation has proven to be particularly advantageous. Due to its low density, this base material can be inserted particularly well into the spaces between the fabric and also into the spaces between the fiber strands. In addition to the use of polymethyl methacrylates as a base material, the above-mentioned epoxy resins, styrene-butadiene rubbers and acrylates or polyurethanes are also conceivable.

In order to create a solid bond between the soaked textile reinforcement and the surrounding concrete, the surface of the soaked fabric is roughened and thus enlarged. For this purpose, additives in the form of particles are added to the coating medium, which cause such an increase in surface area. Granite, quartz powder, cement stone or conductive particles are used. The enlarged surface leads to a force-fitting and positive connection (reinforcement effect). By adding conductive particles, the charge transfer can be optimized to improve cathodic corrosion protection. Alternatively or additionally, ionic compounds, concrete admixtures, mixtures of salts and microsilica (as a suspension or in solid form) or pozzolanic reactives can also be used. These can influence the hardening reaction kinetics, for example when using salts on the one hand, to increase the conductivity in the border area and, on the other hand, to increase the mortar strength in the fabric environment.

In addition to or in addition to increasing the surface of the fabric by adding particles, in an advantageous embodiment a coating can also be applied to the already soaked fabric so that, like the particles, the surface area is enlarged or the additives are better integrated. This coating can then either represent the carrier medium for the particles or itself ensure a higher bond. In a preferred embodiment, additives to improve the electrical, thermal or mechanical properties are also added to this coating medium before, during or after application to the soaked fabric.

The impregnation or coating can be applied in particular using an immersion bath process, an emulation process, a spray process or even brushed or rolled.

The advantages achieved with the invention are, in particular, that by using an impregnation of the fabric that is tailored to the respective area of application and modified by an additive, in the case of a carbon fabric, in particular the carbon fibers, carbon threads or the entire carbon-containing fabric, the properties of the reinforcement the mortar in the immediate vicinity of the reinforcement can also be influenced. In addition to flat surfaces, curved structures exposed to the weather and traffic can be permanently protected from steel corrosion and at the same time mechanically reinforced. A particular advantage is that with suitable modification of the mechanical properties it can be achieved that the carbon fabric used here as a thin-layer textile concrete can provide sufficient load-bearing capacity or an increase in load-bearing capacity even without combination with cathodic corrosion protection. In addition, the removal of thin old coverings that are no longer necessary for load-bearing capacity (such as screed, asphalt or low-strength concrete) can lead to a reduction in load, an increase in load capacity and greater clearance heights in parking garages.

Increasing the strength near the fibers leads to an improvement in performance without causing excessive shrinkage cracking. Furthermore, penetration into the tissue can be improved by adding flow agents to the fiber.

In detail, the main advantages of the coating medium used lie in the improvement of the electrical, chemical and mechanical properties of the entire system, in particular in the high mechanical resilience and load-bearing capacity of the materials used (e.g. in static and dynamic tensile, adhesive tensile and shear loads), long-term resistance to environmental influences, i.e. H. chemical inertness and temperature resistance in a temperature range from -20°C to 80°C. The load behavior can be improved in a larger temperature range. Furthermore, the advantages lie in the flexible processing and deformability (drapeability) while at the same time sufficient rigidity for laying the textile reinforcement. Connections across corners and edges can be made in a non-positive and electrically conductive manner. The rigidity also makes it easy to use when laying. Further advantages include the high bond strength between concrete and textile reinforcement (possibly through the additional use of a coating) and the optimized conductivity in the "metallic" conductor (carbon, 1st order conductor) and good charge transfer to the ionic conductor (cement stone; 2nd order conductor). . Order).

A fabric produced according to the above method is explained in more detail in a drawing in an exemplary embodiment of the invention.

• Fig. 1 ein Querschnitt durch einen Faden des Geleges
• Fig. 2 ein Gelege mit einer eingenähten Primäranode

It shows:

• Fig. 1 a cross section through a thread of the fabric
• Fig. 2 a fabric with a sewn-in primary anode

In Fig. 1 a thread 2 of a scrim is shown in cross section. The thread 2 comprises a large number of individual carbon multifilaments 12, each of which have between several 1,000 and up to 100,000 individual filaments. The thread 2 is in the exemplary embodiment Fig. 1 provided with an impregnation 10, to which one or more additives 14 were added in the impregnation process in order to improve the electrical, mechanical or thermal properties. In a subsequent production step, the thread 2 has been coated with a coating medium 16. In the present case, sanding took place so that the coating 16 serves as a carrier medium for the particles 18. The sanding increases the surface area of the thread 2, which results in better bonding properties with the mortar.

The clutch 1 after Fig. 2 comprises a plurality of threads 2 or strands that are arranged in two levels. Each level includes a number of threads 2, which are spaced apart and essentially parallel to one another. Each of these threads 2 comprises a number of carbon multifilaments, which in the present exemplary embodiment were glued into an elongated strand. However, it is also conceivable that these carbon multifilaments are sewn into a strand or connected in another way. The threads 2 of two levels are essentially orthogonal to one another, which is why a lattice structure with square spaces is formed. The threads 2 are fixed at the crossing points 4 with a continuous sewing thread 6, but can also be glued or connected to one another in another way.

It goes without saying that the planes of the fabric 1 do not necessarily have to be arranged orthogonally to one another, but can also be arranged offset at a different angle depending on the intended use. It is also conceivable that more than two levels can be provided.

In the exemplary embodiment according to the Fig. 2 A band-shaped primary anode 8 is sewn along the entire length of a thread 2, whereby the anode system can be supplied with current over the entire length, in contrast to contacting at a single point. In addition to sewing the primary anode 8 onto a thread 2, it is also conceivable that the primary anode 8 is sewn into a thread 2 is sewn in and is therefore essentially completely surrounded by carbon multifilaments.

In order to increase the mechanical, electrical and thermal properties, in particular to improve the layability and activation of the mechanical properties of the scrim 1 and also of the anode system embedded in the mortar, an impregnation 10 and then a coating are applied to the scrim 1 in accordance with the above statements. By appropriately selecting the impregnation and coating recipe and adding appropriate additives, a fabric 1 can be provided for an anode system which has optimal mechanical, electrical and thermal properties for the respective application and location.

Reference symbol list

1

Clutch

2

thread

4

crossing point

6

sewing thread

8th

primary anode

10

impregnation

12

Carbon multifilaments

14

Additive

16

Coating

18

particles

Claims (6)

1. A process for the production of a textile reinforcement produced from a non-crimp fabric (1), wherein an impregnation (10) is applied to a filament (2) of the non-crimp fabric (1) or to the non-crimp fabric (1), wherein the impregnation (10) comprises a base material to which at least one additive (14) is admixed, characterized in that subsequently, at least one coating (16) with additives in the form of particles (18) is applied in order to increase the surface area, wherein the particles comprise granite, quartz powder, hydrated cement or conductive particles.
2. The process for the production of a textile reinforcement as claimed in claim 1, characterized in that the base material is synthesized from a monomer and a starter by radical polymerization and wherein the additive (14) is admixed with the monomer, the starter, or the synthesized base material.
3. The process for the production of a textile reinforcement as claimed in claim 1 or claim 2, characterized in that a polymethylmethacrylate is used as the base material.
4. The process for the production of a textile reinforcement as claimed in claim 1, characterized in that the additive is admixed in the form of particles (18) prior to, during or after coating the non-crimp fabric.
5. The process for the production of a textile reinforcement as claimed in one of claims 1 to 4, characterized in that the impregnation (10) is applied in a dipping process, an emulation process, or a spraying process.
6. A textile reinforcement produced in accordance with a process as claimed in claims 1 to 5.

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