Composite reinforcement

Composite reinforcements (100, 100A, 100B, 100C) are formed by combining a first plurality of continuous fibers (102) with a second plurality of continuous fibers (106) with the first and second pluralities of continuous fibers (102, 106) being impregnated with at least one appropriate resin material (R1, R2, R3) and pultruded to form the reinforcements. The first and second pluralities of continuous fibers (102, 106) can be intermixed with one another or combined as a central core (104, 132) of the first fibers with a jacket (108, 108A, 108B, 134) formed by the second fibers. In either event, the combined fibers are formed as an elongated rod (110) and rigidified using the resin material. The first fibers are glass, either E-glass or S-2 glass, with the second fibers being either carbon, aramid, S-2 glass or AR-glass. The composite reinforcements of the present application, formed by combining these materials, have characteristics very similar to steel under tensile loading but with superior corrosion resistance and less detrimental deterioration characteristics.

TECHNICAL FIELD 
This invention relates to reinforcement materials for use in the 
construction industry and, more particularly, to reinforcement materials 
made as a composite of a first plurality of continuous fibers which are 
combined with a second plurality of continuous fibers. The first and 
second pluralities of continuous fibers can be intermixed with one another 
or combined as a central core of the first fibers with a jacket formed by 
the second fibers. In either event, the combined fibers are formed as an 
elongated bar or rod and rigidified using resin material. The terms bar 
and rod as used herein should be considered substantially equivalent and 
interchangeable to indicate a generally elongated, slender structure. 
BACKGROUND OF THE INVENTION 
Steel reinforcing bars are used throughout the construction industry. Such 
bars are most commonly used for reinforcing concrete used in many building 
applications, with the concrete being reinforced with steel reinforcing 
bars and/or wire meshes. The reinforcing bars are wired together to form 
the frameworks or skeletons for building columns and floors in concrete 
structures. In addition to such static reinforcements, steel wires or 
cables are heavily loaded to compress concrete in concrete slabs and the 
like to reduce or eliminate cracking and tensile forces with the wires or 
cables being pre-tensioned or post-tensioned depending upon the 
application. Steel wire or cable tensioning can also be applied to wood 
structures, for example for post-tensioning of wood decks for bridges. 
Unfortunately, steel reinforcing bars or rods and tensioning wires or 
cables are subject to corrosion over time which deteriorates these 
reinforcing materials and thereby the structures which include them. While 
deterioration can occur even in the most protected environments, it is 
common and costly in harsh environments such as structures erected in a 
marine environment and in slabs used for automobile traffic or parking in 
climates where salt is applied to roads and bridge decks to control snow 
and icing conditions. Deterioration of reinforcing bars or rods and 
tensioning wires or cables usually requires replacement of the associated 
structure or significant repair. In either event, correction of the 
deteriorated reinforcing bars or rods and tensioning wires or cables is 
costly. 
There is, thus, a need for improved, deterioration-resistant reinforcements 
to be used in place of steel reinforcing bars or rods and tensioning wires 
or cables in the construction industry. Preferably, such improved 
reinforcements would be used as direct replacements for existing steel 
reinforcing bars or rods and tensioning wires or cables, and would improve 
the life expectancy of reinforced structures particularly where such 
structures are erected in harsh environments including, for example, 
marine installations. 
DISCLOSURE OF INVENTION 
This need is met by the invention of the present application wherein 
composite reinforcements are formed by combining a first plurality of 
continuous fibers with a second plurality of continuous fibers with the 
first and second pluralities of continuous fibers being impregnated with 
at least one appropriate resin material and pultruded or otherwise 
processed to form the reinforcements. The first and second pluralities of 
continuous fibers can be intermixed with one another or combined as a 
central core of the first fibers with a jacket formed by the second 
fibers. In either event, the combined fibers are formed as an elongated 
bar or rod and rigidified using resin material. The first fibers are 
glass, either E-glass or S-2 glass, with the second fibers being either 
carbon, aramid, S-2 glass or AR-glass (alkaline resistant). The composite 
reinforcements of the present application, formed by combining these 
materials, have characteristics very similar to steel under tensile 
loading but with superior corrosion resistance and less detrimental 
deterioration characteristics. The superior characteristics are due to the 
protection afforded by the resin material when the fibers are intermixed, 
and in addition by the shielding effects afforded by the jacket of 
impregnated second fibers when a core/jacket configuration is used. In 
this regard it is noted that composites made from carbon, aramid, S-2 
glass and AR-glass together with the resin materials are substantially 
immune to the corrosive environments which are the cause of corrosion and 
deterioration of conventional reinforcement materials used in the 
construction industry. 
In accordance with one aspect of the present invention, a composite 
reinforcement for use in construction comprises a first plurality of 
continuous fibers with a second plurality of continuous fibers being 
associated with the first plurality of continuous fibers. Resin material 
impregnates the first and second pluralities of continuous fibers which 
are formed into an elongated rod and rigidified by the resin material. In 
one embodiment of the invention, the first and second pluralities of 
continuous fibers are intermixed with one another. In another embodiment 
of the invention, the first plurality of continuous fibers comprises a 
core and the second plurality of continuous fibers comprises a jacket 
formed about the core. To help secure the composite reinforcement within 
material being reinforced, the jacket may be formed to have a textured 
surface. 
The first plurality of continuous fibers comprises glass fibers, for 
example E-glass or S-2 glass, and the second plurality of continuous 
fibers comprises fibers having a higher modulus of elasticity and a 
different ultimate strain than the first plurality of fibers. The 
combination of high modulus and low modulus fibers and the different 
failure strains results in a composite reinforcement which exhibits 
pseudo-ductile behavior. When stressed beyond its initial point of 
failure, a material that is pseudo-ductile will continue to carry a load 
but with a significant loss in stiffness. Accordingly, the pseudo-ductile 
failure mode is very desirable for structural materials and reinforcements 
for structural materials. The second plurality of fibers may comprise, for 
example, carbon fibers, aramid fibers, S-2 glass or AR-glass. 
In accordance with another aspect of the present invention, a composite 
reinforcement for use in construction comprises a core of continuous glass 
fibers with a continuous carbon fiber jacket formed about the core. At 
least one resin material impregnates the core and the carbon jacket. In 
one form of the invention, a first resin impregnates the core and a second 
resin impregnates the continuous carbon fiber jacket. The composite 
reinforcement may be circular in cross section, elliptical in cross 
section or have other geometric shapes as a cross section. The composite 
reinforcement may be formed to have a textured surface to help secure the 
composite reinforcement within material being reinforced. The at least one 
resin material may comprise a thermosetting resin or a thermoplastic 
resin. The composite reinforcement includes a cross-sectional dimension 
which ranges from approximately 0.125 inch to 1.5 inch. The carbon fiber 
jacket may comprise continuous carbon fibers over-wrapped and knitted 
about the core with the continuous carbon fibers being knitted about the 
core at an angle between 0.degree. and 90.degree.. A volume fraction of 
glass fibers plus carbon fibers to the resin material ranges from about 
0.40 to 0.85, i.e., the percentage of the glass fibers plus the carbon 
fibers to the at least one resin material ranges from about 40% to 85%. 
It is, thus, an object of the present invention to provide improved 
reinforcements for use in the construction industry wherein a first 
plurality of continuous fibers is combined with a second plurality of 
continuous fibers with the first and second pluralities of continuous 
fibers being impregnated with at least one resin material and processed, 
for example by pultrusion and solidification or curing, to form the 
reinforcements. 
Other objects and advantages of the invention will be apparent from the 
following description, the accompanying drawings and the appended claims.

MODES FOR CARRYING OUT THE INVENTION 
Composite reinforcements in accordance with the present invention and 
methods of making the reinforcements will now be described with reference 
to the drawings. The composite reinforcements are for use in the 
construction industry for providing more corrosion resistance than steel 
reinforcing bars or rods and tensioning wires or cables. The composite 
reinforcements may also be used in other related applications including 
energy efficient sandwich panels and walls as well as other applications 
which will be suggested to those skilled in the art by the following 
description. 
FIG. 1 illustrates a portion of a first embodiment of a composite 
reinforcement 100 which comprises a first plurality of continuous fibers 
102 which have been formed into a core 104. The first plurality of 
continuous fibers 102 is impregnated with an appropriate thermoplastic or 
thermosetting resin material R1, as will be described more fully with 
regard to making the reinforcements, and at least partially solidified or 
cured to form the core 104. As illustrated, the composite reinforcements 
are circular; however, the reinforcements can also be elliptical or have 
other geometric cross sections as should be apparent, for example see FIG. 
4D which illustrates a composite reinforcement 100D having an elliptical 
cross section. The first plurality of continuous fibers 102 may be made up 
of E-glass fibers for most applications; however, other glass fibers such 
as S-2 glass fibers and alkaline resistant AR-glass fibers can also be 
used. 
A second plurality of continuous fibers 102, woven or otherwise formed into 
ribbons 106R for the embodiment of FIG. 1, is associated with the first 
plurality of continuous fibers 102. As illustrated, the ribbons 106R are 
knitted to form a jacket 108 over-wrapped about the core 104 and thereby 
are associated with the first plurality of continuous fibers 102. The 
second plurality of continuous fibers 106, i.e., the jacket 108, is 
impregnated with an appropriate thermoplastic or thermosetting resin 
material R2, which can be the same as or different than the resin material 
R1 of the core 104, with the entire resulting composite reinforcement 
being formed into an elongated rod 110 and the resin material solidified 
or cured to rigidify the composite reinforcement 100. 
The first embodiment of FIG. 1 is also shown in cross section in FIG. 2. 
The second plurality of continuous fibers may be made up of continuous 
carbon fibers for most applications; however, other fibers, such as S-2 
glass, AR-glass and aramid fibers can also be used. It is advantageous to 
use such fibers, particularly as a jacket, for composite reinforcements 
since they, as well as the resin materials which are used to impregnate 
them, are substantially immune to corrosive environments including saline 
and acidic environments which are the primary cause of corrosion and 
deterioration in conventional steel reinforcement materials used in the 
construction industry. Preferably, the core 104 makes up from about 99% to 
50% of the cross sectional area of the composite reinforcement 100 with 
the jacket 108 complementing the core 104 by making up from about 1% to 
50% of the cross sectional area of the composite reinforcement 100. 
FIG. 3 illustrates a sectional view of a first alternate embodiment of a 
composite reinforcement 100A of the present invention wherein the inner 
core 104 of the first plurality of parallel fibers 102 and resin material 
R1 is over-wrapped by a jacket 108A formed by a second plurality of 
parallel fibers 106 and resin material R2. The composite reinforcement 
100A of FIG. 3 is similar to the composite reinforcement 100 of FIGS. 1 
and 2 except for the formation of the jacket 108A by the second plurality 
of parallel fibers 106. Due to the structure of the jacket 108A, the 
composite reinforcement 100A may be formed without initial formation of 
the core 104 and, hence, may be formed more easily than the composite 
reinforcement 100 of FIGS. 1 and 2. 
The embodiment of FIG. 3 can be altered by modification of the pultrusion 
method used to form a composite reinforcement 100B such that a textured 
surface 112 is formed on the outside of the jacket 108B, see FIG. 4. The 
resulting composite reinforcement 100B has ridges 114 which run axially 
along the composite reinforcement 100B and help secure the composite 
reinforcement 100B within material which it is being used to reinforced. 
Other surface textures can be formed into the outer surfaces of composite 
reinforcements of the present invention either by modifying the cross 
section of the pultrusion die used to form the composite reinforcement or 
by subsequent operations. For example, regular or randomly formed patterns 
of protrusions can be formed on the outer surface of composite 
reinforcements by adding additional fibers and/or resin material on the 
reinforcements by a post processing station 116, see FIG. 6. FIGS. 4A-4C 
illustrate circumferential ribs R formed on the composite reinforcement 
100, spiral ribs SR formed on the composite reinforcement 100 and 
criss-crossed ribs CCR formed on the composite reinforcement 100. Of 
course, other patterns of protrusions will be apparent from the 
description of the present application. While such subsequent forming 
operations add to production time and costs, it results in reinforcements 
which may be better secured within a reinforced material and, with respect 
to reinforcing bars, more closely resembling conventional steel 
reinforcing bars. 
A third alternate embodiment of a composite reinforcement 100C is 
illustrated in FIG. 5 wherein the first plurality of continuous fibers 102 
are intermixed with the second plurality of continuous fibers 106. It is 
currently believed that a random intermixing of the first and second 
pluralities of continuous fibers 102, 106 as illustrated is preferred; 
however, patterns of mixing can be used in the present invention. The 
first and second pluralities of continuous fibers are impregnated with an 
appropriate thermoplastic or thermosetting resin material R and formed 
into an elongated rod and solidified or cured to rigidify the composite 
reinforcement 100C. 
Formation of the composite reinforcement 100C is, thus, more simple than 
the formation of the composite reinforcements 100, 100A and 100b since the 
jacket of those embodiments has been incorporated into the structure of 
the composite reinforcement 100C by intermixing the first and second 
pluralities of continuous fibers 102, 106. It is currently believed that 
composite reinforcements ranging in size from approximately 0.125 inch to 
1.50 inches in diameter or maximum cross sectional dimension will be 
necessary for reinforcement applications. However, other sizes may be made 
as required. 
A significant aspect of the present invention is that the first and second 
pluralities of continuous fibers have differing moduli of elasticity and 
differing ultimate strain capacities. The combination of such high modulus 
and low modulus fibers and the different failure strains results in a 
composite reinforcement which exhibits pseudo-ductile behavior. 
With this understanding of the various structures of the composite 
reinforcements of the present invention, reference will now be made to 
FIG. 6 for a description of how the composite reinforcements can be made. 
Since the structure of the composite reinforcement 100 of FIGS. 1 and 2 is 
more complex than the other alternate embodiments, its production will be 
described. Modifications for producing the other alternate embodiments 
described above as well as additional embodiments which will be suggested 
from this description will be apparent to those skilled in the art. 
The first plurality of fibers 102 can be supplied from a single source of 
such fibers. As shown in FIG. 6, the first plurality of fibers 102 is 
assembled from a plurality of fiber sources 120A-120X. The first plurality 
of fibers 102 are drawn through a corresponding number of wet-out stations 
122A-122X where the fibers are impregnated with an appropriate resin 
material R1: a thermoplastic resin material such as a polypropylene, an 
acrylic, a cellulosic, a polyethylene, a vinyl, a nylon or a fluorocarbon; 
or, a thermosetting resin material such as an epoxy, a polyester, a 
vinylester, a malamine, a phenolic or a urea. The impregnated fibers are 
then passed through a pultrusion die 130 where the impregnated fibers are 
formed into an elongated core 132. Composite reinforcements can also be 
formed using extrusion, injection molding, compression molding and other 
appropriate processes. 
Either immediately after production, as illustrated, or at a subsequent 
time, a jacket 134, such as the jacket 108 of FIGS. 1 and 2, is 
over-wrapped about the core 132 by knitting ribbons 136 woven or otherwise 
formed from the second plurality of continuous fibers 106. The ribbons 136 
are provided from ribbon sources 138A-138Y, schematically illustrated as 
spools, which feed a cross-head winder or under-knitter 140. The 
cross-head winder or under-knitter 140 winds or knits the ribbons 136 as 
shown in FIG. 1 at a knitting angle typically around 45.degree.; however, 
the knitting angle can vary between 0.degree. and 90.degree.. By knitting 
the jacket 108 about the core 132, the core 132 is better encased or 
enclosed by the jacket 108 to thereby better protect the core 132 from 
corrosive environments. Cross-head winders and knitters are well known in 
the art and will not be further described herein. 
The ribbons 136 or strands of reinforcing fibers 106 used to form the 
jacket 108 may be preimpregnated with an appropriate resin R2 or the 
resulting jacketed core 144 may be drawn through a wet-out station 146 
where the jacket 134 is impregnated with an appropriate resin material R2: 
a thermoplastic resin material or a thermosetting resin material, which 
can be the same as or different than the resin material R1. The jacketed 
core 144 with the jacket 134 thus impregnated is then passed through a 
curing die 148 or otherwise processed. Preferably, the volume percentage 
of fibers to resin(s) ranges between approximately 40% and 85%. 
It is noted that either resin baths or resin injection can be used to 
saturate the fibers to produce the composite reinforcements of the 
invention. Accordingly, the wet-out stations 122A-122X and 146 shown in 
FIG. 6 can be either resin baths or resin injection dies. Since both forms 
of resin impregnation are well known in the art, they will not be more 
fully described herein. It should also be apparent that the composite 
reinforcement 100C of FIG. 5 can be produced by the apparatus up to and 
including the pultrusion die 130. 
Having thus described the invention of the present application in detail 
and by reference to preferred embodiments thereof, it will be apparent 
that modifications and variations are possible without departing from the 
scope of the invention defined in the appended claims.