US20040213976A1

US20040213976A1 - Non-metallic reinforcement member for the reinforcement of a structure and process of its manufacture

Info

Publication number: US20040213976A1
Application number: US10/481,908
Authority: US
Inventors: Suong Hoa
Original assignee: Individual
Current assignee: Concordia University
Priority date: 2001-06-22
Filing date: 2002-06-21
Publication date: 2004-10-28
Also published as: WO2003001005A1; CA2451336A1

Abstract

Disclosed herein is a non-metallic reinforcement member (10) such as a rod to be embedded in a structure of material such as concrete (30). This member comprises a longitudinal main body (20) having an outer surface (14) and spaced apart embossments (22) formed along its length and being integral therewith. When this member (10) is embedded in concrete (30), the embossments (22) mechanically interlock with the concrete (30). This reinforcement member (10) may be made of a plastic material such as thermoplastic resin so as to be bendable. The outer surface (14) may comprise layers of fiber reinforcement (18). Also disclosed herein is a process of making such a reinforcement member (10).

Description

FIELD OF THE INVENTION

The present invention generally relates to a member for the reinforcement of a structure of material. More specifically, the present invention is concerned with a fiber reinforced plastic rod for the reinforcement of concrete.

BACKGROUND OF THE INVENTION

Concrete materials have been used extensively in many civil engineering structures. These include bridges, walls for buildings, parking garages, wave breaking structures along seashores etc. This is because concrete has good durability at ambient operating conditions, and also because of its low cost. However, concrete is usually strong in compression but weak in tension. As such, to reinforce concrete in applications where tension load is present, steel reinforcing rods have been used. Steel reinforced concrete is ever present in our everyday lives, and these materials have been used in construction projects for many years.

Steel is used to reinforce concrete due to its good strength, toughness and ductility. However, steel does suffer from corrosion. Moisture and water does attack and corrode steel. Particularly in cold climates like in Canada an in many states in the United States, where salt is used to de-ice each winter, the problem of corrosion of steel in concrete used in roads and bridges is even worse. The repair of the Montreal Champlain bridge across the St. Lawrence River is one example. Every year, workers have to cut up the concrete, dig up the steel reinforcing rods, clean them of rust, and apply an epoxy coating before putting the concrete over them again. This repair is expensive, not only in the cost of cutting, digging, repair but also in terms of the disruption of traffic and causes disturbance to many commuters. This problem is not unique to just the Champlain bridge alone. Many infrastructures in many cities in Canada, the U.S., and even Europe have been in operation for more than 40 years, and they are reaching a stage where either rehabilitation or replacement is necessary. The enormous cost of this project certainly requires some good thinking about how one should do the job better, so that at least the life of these structures can be longer than what they used to be.

Fiber reinforced plastic (FRP) rods have been receiving a lot of attention as an alternative for steel in the reinforcement of concrete. This is due to the excellent corrosion resistance of FRP materials in environment that corrodes steel, such as water and alkali. As such, there has been accelerated research going on in this area and there are many companies that manufacture and sell the FRP rods. The current FRP rods have diameters that vary from 12.7 mm to 25.4 mm. They are made by pultrusion technology where the fibers wetted with resins are pulled through a heated die where they consolidate and cure. A product made by this technique has good properties in terms of stiffness and strength along the direction of the rod. However, the cross section is uniform. This uniformity in cross section allows long length to be made economically. However, in terms of providing reinforcement to the concrete, the uniformity of cross section can only rely upon friction at the interface between the rod and the concrete. There is no mechanical interlock between the rod and the concrete. Steel rods have some form of mechanical interlock built in by the calendering process. Some manufacturers of FRP rods also try to mimic this mechanical interlock either by adding helical tows on the surface of the FRP rods, or to add sand particles to the surface of the FRP rods to increase the roughness. However, these additions are only bonded to the main rod by secondary bond with very low shear resistance. The result is that the FRP rods exhibit low shear transfer to the concrete as compared to that of steel.

Fiber reinforced plastic materials consist of fibers such as glass fibers, carbon fibers, kevlar fibers; and matrix materials such as epoxy, polyester, thermoplastics. These fiber reinforced plastic materials are strong, and corrosion resistant. These materials lend themselves well as an alternative to steel in making reinforcing rods for concrete. Over the past ten years, there has been intensive research activity in the development of these fiber reinforced plastic rods. These rods are made by a process called Pultrusion. In this process, the fibers (wetted with resins) are pulled through a heated die. During this pulling process, the resin hardens and the fibers and resins consolidate into a hard and strong material. These pultruded rods have been made and commercialized by companies in North America and in Japan. In Canada, there is Pultrall in Thetford Mines. In the United States, there are Hughes Brothers, Master Builders etc. The pultruded rods seem to be an excellent alternative to steel for the reinforcement of concrete.

However, conventional fiber reinforced plastic rods still suffer from two major drawbacks. Firstly they are made by the pultrusion process. As such their cross section is uniform along the length of the rod. Since the rod depends on friction between the concrete and the rod for the reinforcement, the uniform cross section does not provide much resistance. Many of the manufacturing companies have added external ribs to improve the frictional resistance. However, these ribs are held to the rod by weak secondary bonds and the resistance is only marginally improved. Secondly, the resin used is polyester, which is a thermoset. As such, the material is brittle and it is very difficult if not impossible to bend a rod. This lack of workability limits the ability of the field worker to bend the rod to fit to a certain geometrical constraint on the job.

OBJECT OF THE INVENTION

The general object of the present invention is therefore to provide an improved reinforcement member for the reinforcement of a structure of material.

SUMMARY OF THE INVENTION

More specifically, in accordance with the present invention there is provided a reinforcement member to be embedded in a structure of material, this member comprises a longitudinal main body having an outer surface and spaced apart embossments formed along the length of the longitudinal body, these embossments are integral with the longitudinal main body, wherein, when the member is embedded in the structure, the embossments mechanically interlock with the structure.

In accordance with another aspect of the present invention there is provided a process for making the reinforcement member disclosed herein, the process comprises:

(a) making a core having the configuration of the member;

(b) making a tube of yarns;

(c) incorporating the core within said tube so as to provide a core-tube assembly;

(d) placing the core-tube assembly within a bag of high temperature resistant material;

(e) exposing the bagged core-tube assembly to such temperature and pressure as to mold said core-tube assembly into the reinforcement member;

(f) providing for the reinforcement member to solidify; and

(g) removing the bag from the reinforcement member.

An advantage of the present reinforcement member is that the embossments along the length of its longitudinal main body provide for the mechanical interlock of the reinforcement member with the structure that is to be reinforced, rather than just interfacial friction alone.

Another advantage of the present reinforced member is that it is made using thermoplastic resin which allows the reinforcement member to be bendable.

An advantage of the process for making the reinforcement member of the present invention is that it is relatively inexpensive.

It should be understood that the term “rod” herein may be construed to mean “bar”, “rebar” and the like.

It should also be understood that the term “non-metallic” may be construed to mean substantially having no metal so as to substantially avoid corrosion.

Other objects, advantages and features of the present invention will become more apparent upon reading of the following non restrictive description of preferred embodiments thereof, given by way of example only with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the appended drawings in which the reference numbers indicate like elements and in which: [0023]
FIG. 1 is a perspective view of a reinforcement member in accordance with a preferred embodiment of the present invention; [0024]
FIG. 2 is a lateral elevational view of the reinforcement member of FIG. 1; [0025]
FIG. 3 is a cross-sectional view of the reinforcement member of FIG. 2 along the line [0026] 3-3; and
FIG. 4 is a view of the reinforcement member similar to FIG. 3, with the reinforcement member being embedded in concrete.[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to the appended drawings a preferred embodiment of the present invention will be described hereinbelow: [0028]
FIGS. 1 and 2 illustrate a preferred embodiment of the reinforcement member according to the present invention, generally denoted [0029] 10; and adapted to be embedded in a structure of material for the reinforcement thereof.
[0030] Member 10 may be used to reinforce a variety of structures made for a variety of materials as is known in the art, in one aspect of the present invention member 10 is used for the reinforcement of a mass of concrete.
[0031] Member 10 can be a rod or any like elongated structure in accordance with the present invention.
The member or [0032] rod 10 is made of a non-metallic material or includes substantially no metal. In this way the rod is substantially non-corrosive. Hence, the rod may be made of non-corrosive materials. Advantageously, member or rod 10 is made of a plastic material. Preferably the plastic material is a thermoplastic resin. Thermoplastic resin provides for rod 10 to be bendable.
As aforementioned this [0033] rod 10 may be a solid piece of material or may be a tube over an appropriate core as will be more clearly explained when the process of making the present invention is described below.
[0034] Rod 10 comprises a longitudinal main body 12 having an outer surface 14 (see FIGS. 3 and 4). It is advantageous that this outer surface 14 includes no metal or non-corrosive materials.
The [0035] body 12 may be a generally cylindrical configuration. Of course, it is within the scope of the present that the longitudinal main body 12 may have another suitable configuration, what is advantageous is that the longitudinal main body 12 be configured and sized for being embedded in a structure of material for the reinforcement thereof.
As shown, the longitudinal [0036] main body 12 includes embossments-16.
Embossments [0037] 16 are structurally integral with the longitudinal main body 12 and are spaced apart in non-contiguous fashion along the length of the longitudinal main body 12. As shown, embossments 16 have a generally ellipsoidal configuration. Of course, the embossments 16 may have any other configuration that would provide the best efficiency of reinforcement as is known to the ordinary skilled artisan. Furthermore, the embossments 16 may be equally or unequally spaced apart depending on the requirements from the design of the structure that is to be reinforced. The selection of the size, width, general configuration of the embossments 16 as well as the space between each embossment 16 is a function of the dimension of the rod 10 and the type of material and structure that is to be reinforced.
FIG. 3 shows that layers of [0038] outer fiber reinforcement 18 be placed along the length of the rod 10.
As will be better explained when the process of making the present invention is detailed below the [0039] fiber reinforcement material 18 may be a braided tube over an appropriate core 20 (see FIG. 3).
Of course the [0040] rod 10 may be made of a single piece of material.
In operation and with particular reference to FIG. 4, [0041] rod 10 will be embedded in a structure of material such as concrete 30 for example.
As is known to the skilled artisan, the general configuration and size of the [0042] rod 10 will depend on the type of concrete 30 that is to be reinforced.
Due to its thermoplastic resin composition rather than being made of thermoset resin (such as polyester or epoxy) as with the current rods, the [0043] rod 10 will be bendable allowing flexibility for the field worker to work on the rod 10 to fit the constraints of the geometry of the job.
The [0044] embossments 16 provide for the rod 10 to have varying cross sections along its length, which provide mechanical interlock with the concrete 30 rather than just interfacial friction alone. Hence, the shear transfer between the rod 10 and the concrete 30 is through mechanical interlock, in addition to the friction between the rod outer surface 14 (including the layers of fiber reinforcement 18) and the concrete 30. As such, rod 10 is a much more effective reinforcing member.
The reinforcement member of the present invention may be produced as described hereinbelow. [0045]
As shown in FIGS. 3 and 4, a [0046] core member 20 is made having the configuration of the reinforcement member 10 including the embossments 16. The core member 20 material is made of high temperature resistant material.
Advantageously, the [0047] core 20 is a solid cylinder with embossments 22 (see FIGS. 3 and 4) along its length. The embossments 22 of the core provide the form for the embossments 16 of the reinforcement member 10. The core 20 can be made of an inexpensive material such as low-cost ceramic, metals or plastics. The embossments 22 along the length of the core can be made by machining a larger diameter rod (not shown) into a smaller diameter rod (not shown) with the embossments 22 remaining. The total core member 20 with embossments 22 can also be molded or cast using appropriate tooling. The aspect ratio of the embossment 22 (width over length) on the core depends on the reinforcement effect required. The pitch of embossments 22 (distance between embossments) varies depending on the required reinforcement effect.
A [0048] tube 18 is made of mingled fibers and plastic yarns. Advantageously the comingled fibers and plastic yarns are braided into a braided tube.
Preferably, this [0049] tubular braid 18 is made by braiding tows consisting of comingled stiff and strong fibers (such as carbon, glass, aramid) together with fibers made of a thermoplastic material (such as polyamide, polypropylene, polyethylene). The braid consists of axial tows and helical tows. Advantageously, the amount of axial tows is much larger than the amount of helical tows to ensure good properties along the axial direction. The tubular braid 18 should have an inside diameter appropriate to the size of the reinforcing member 10 to be made. The braid 18 can be made with a mandrel or without the mandrel. When the braid 18 is made with the mandrel, then the core member 20 is used as the mandrel. When the tubular braid 18 is made without the mandrel, then the core 20 is inserted into the braided tube 18 afterwards as will be described below. Making the tubular braid 18 without the mandrel provides flexibility in infinite length of the braided tube 18, which can significantly reduce the cost of production.
The [0050] core 20 is incorporated into the braided tube providing a core-tube assembly.
In one example, the incorporation of the [0051] core 20 inside the braided tube 18 is done by using the core 20 as the mandrel for braiding as described above. If the core 20 is not used as the mandrel and the braid tube is made without the core 20, then the core 20 can be inserted into the braided tube 18. Insertion can be done by sliding the core 20 along the length of the braided tube 18. Care should be taken to assure the uniform distribution of the braided tows on the core 20.
The core-tube assembly is then placed inside a high temperature resistant bagging material (not shown). [0052]
Advantageously, the high temperature bagging material should withstand temperatures high enough to melt the thermoplastic fibers mentioned above. For example, a bagging material made of Kapton can be used. The edges of the bag should be sealed so that vacuum can be drawn inside the bag., The bag is subjected to vacuum so that the bag material presses the [0053] braided material 18 against the core 20 to conform to the configuration of the core 20.
The bagged core-tube assembly is then exposed to high temperature and pressure for a sufficient amount of time for the thermoplastic to melt and to consolidate the [0054] fibers 18 to the shape of the core 20.
The whole bagged assembly is placed inside an oven with facilities to apply both temperature and pressure. The temperature should be large enough to melt the thermoplastic fiber material mentioned above. For example, if polyamide is used, a minimum temperature of 200° C. should be applied for 30 minutes. Pressure is applied to consolidate the [0055] reinforcement member 10. The pressure can range from 100 psi (683 kPa) to 200 psi (1367 kPa).
After the molding process (heating and pressurization for sufficient amount of time), the heat and pressure can be turned off to allow sufficient time for the [0056] reinforcement member 10 to cool down and solidify. The oven can be left to cool normally to room temperature.
The bagging material is removed from the [0057] reinforcement member 10.
It is to be understood that the invention is not limited in its application to the details of construction and parts illustrated in the accompanying drawings and described hereinabove. The invention is capable of other embodiments and of being practiced in various ways. It is also to be understood that the phraseology or terminology used herein is for the purpose of description and not limitation. Hence, although the present invention has been described hereinabove by way of preferred embodiments thereof, it can be modified, without departing from the spirit, scope and nature of the subject invention as defined in the appended claims. [0058]

Claims

What is claimed is:

1. A reinforcement member to be embedded in a structure of material for the reinforcement thereof, said member comprising a longitudinal main body having an outer surface and spaced apart embossments formed along the length of said longitudinal main body, said embossments being integral with said longitudinal main body, wherein, when said member is embedded in the structure, said embossments mechanically interlock with the structure.

2. A reinforcement member according to claim 1, wherein the member is non-metallic.

3. A reinforcememt member according to claim 1, wherein the member is non-corrosive.

4. A reinforcement member according to claim 1, wherein said outer surface is free of metallic material.

5. A reinforcement member according to claim 1, wherein said outer surface is free of corrosive material.

6. A reinforcement member according to claim 1, wherein the structure is concrete.

7. A reinforcement member according to claim 1, wherein said member is a rod.

8. A reinforcement member according to claim 1, wherein said longitudinal body is made of a plastic material.

9. A reinforcement member according to claim 8, wherein said plastic material is thermoplastic resin.

10. A reinforcement member according to claim 1, wherein said longitudinal main body includes a tube over an appropriate core member.

11. A reinforcement member according to claim 10, wherein said tube is a braided tube made from yarns.

12. A reinforcement member according to claim 11, wherein said yarns include intermingled first and second fibers, said first fibers selected from the group consisting of carbon, glass and aramid, said second fibers including of thermoplastic materials.

13. A reinforcement member according to claim 10, wherein said core is made of a material selected from the group consisting of ceramic, metal and plastic.

14. A reinforcement member according to claim 1, wherein said outer surface comprises fiber reinforcement.

15. A reinforcement member according to claim 1, wherein said embossments have a generally ellipsoidal configuration.

16. A reinforcement member according to claim 1, wherein said embossments are equally spaced apart.

17. A reinforcement member according to claim 1, wherein said embossments are unequally spaced apart.

18. A reinforcement member according to claim 1, wherein said member is bendable.

19. A process for making the reinforcement member of claim 1, said process comprising:

(a) making a core having the configuration of the member;

(b) making a tube of yarns;

(c) incorporating said core within said tube so as to provide a core-tube assembly;

(d) placing said core-tube assembly within a bag of high temperature resistant material;

(e) exposing said bagged core-tube assembly to such temperature and pressure as to mold said core-tube assembly into the reinforcement member;

(f) providing for the reinforcement member to solidify; and

(g) removing said bag from the reinforcement member.

20. A process according to claim 19, wherein making a core in (a) includes machining a larger diameter rod into a smaller diameter rod thereby forming embossments along the length of said core.

21. A process according to claim 19, wherein said making a core in (a) includes molding the core.

22. A process according to claim 19, wherein said core is made of a material selected from the group consisting of ceramic, metal and plastic.

23. A process according to claim 19, wherein said making a tube in (b) includes braiding yarns into a braided tube.

24. A process according to claim 23, wherein said yarns are made from intermingled first and second fibers, said first fibers being selected from the group consisting of carbon, glass and aramid, said second fibers including thermoplastic fibers.

25. A process according to claim 24, wherein said thermoplastic fibers are selected from the group consisting of polyamide, polypropylene and polyethylene.

26. A process according to claim 19, wherein said incorporating in (c) includes sliding said core inside said tube.

27. A process according to claim 19, wherein said making a tube in (b) and said incorporating in (c) are simultaneous and include braiding yarns into a braided tube about said core thereby providing said core-tube assembly.

28. A process according to claim 19, wherein said placing in (d) includes subjecting said bag to a vacuum such that said bag presses said tube against core to conform to the configuration of said core.

29. A process according to claim 19, wherein said bag is made of material capable of resisting temperatures high enough to melt thermoplastic fibers.

30. A process according to claim 19, wherein said exposing in (e) includes placing said bagged core-tube in an oven configured to apply both high temperature and high pressure.

31. A process according to claim 24, wherein said bagged core-tube assembly is subject to such temperature as to melt said thermoplastic fibers.

32. A process according to claim 31, wherein said temperature is at least 200° C.

33. A process according to claim 24, wherein said pressure is such as to consolidate said intermingled fibers to the configuration of said core.

34. A process according to claim 33, wherein said pressure is between 683 kPa to 1367 kPa.

35. A process according to claim 19, wherein providing in (f) includes allowing sufficient time for the reinforcement member to cool down.