(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2012/0073231 A1
`
`
` HEMPHILL (43) Pub. Date: Mar. 29, 2012
`
`US 20120073231A1
`
`(54) METHOD AND APPARATUS FOR REPAIRING
`CONCRETE
`
`(75)
`
`Inventor:
`
`William Scott HEMPHILL,
`Wilmington DE (Us)
`’
`
`(73) Assignee:
`
`Garland Industries, Inc.
`
`(21) Appl. No.:
`
`12/893,229
`
`(22)
`
`Filed:
`
`Sep. 29, 2010
`
`Publication Classification
`
`(51)
`
`Int. Cl.
`(2006.01)
`E04G 23/02
`(200601)
`B323 3/0”
`(2006.01)
`B323 5/02
`(52) us. Cl. ........................... 52/514; 428/156; 52/7411
`(57)
`ABSTRACT
`.
`.
`.
`.
`A compos1te materlal used to repalr concrete. The compos1te
`material includes a first fiber system including at least one
`fiber layer. Each fiber layer includes a plurality of fibers. The
`binding material secures together the plurality of fibers. The
`composite material is positioned and secured in a slot cut in a
`concrete structure.
`
`
`
`
`
`Metromont Ex-1007, p.1
`
`Metromont Ex-1007, p.1
`
`

`

`Patent Application Publication Mar. 29, 2012 Sheet 1 0f 5
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`US 2012/0073231 A1
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`
`
`Metromont Ex-1007, p.2
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`Metromont Ex-1007, p.2
`
`

`

`Patent Application Publication Mar. 29, 2012 Sheet 2 0f 5
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`US 2012/0073231 A1
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`Patent Application Publication Mar. 29, 2012 Sheet 3 0f 5
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`US 2012/0073231 A1
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`Metromont Ex-1007, p.4
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`Metromont Ex-1007, p.4
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`Patent Application Publication
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`Mar. 29, 2012 Sheet 4 0f 5
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`US 2012/0073231 A1
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`Metromont Ex-1007, p.5
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`Metromont Ex-1007, p.5
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`Patent Application Publication Mar. 29, 2012 Sheet 5 0f 5
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`US 2012/0073231 A1
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`Metromont Ex-1007, p.6
`
`

`

`US 2012/0073231 A1
`
`Mar. 29, 2012
`
`METHOD AND APPARATUS FOR REPAIRING
`CONCRETE
`
`[0001] The present invention is directed to a method and
`apparatus for strengthening concrete, more particularly
`directed to a method and apparatus for strengthening and/or
`repairing concrete connections, and still more particularly
`directed to a method and apparatus for repairing the flange-
`to-flange connections for precast and prestressed double tee
`systems.
`
`BACKGROUND OF THE INVENTION
`
`[0002] Concrete structures are commonly used for build-
`ings, packing garages and the like. Over time, cracks can
`develop within concrete structures. If such cracks are left
`unrepaired, the cracks can result in failure of the structure.
`This is a particular problem for parking garages wherein large
`loads from vehicles daily travel over the concrete surface. To
`prevent the failure of the concrete structure without having to
`replace the entire concrete structure, the damaged concrete
`structure is often repaired by cutting the damaged section
`away from a preexisting concrete section, and then pouring
`new concrete into the cutout portion. However, new concrete
`does not always bond perfectly with the preexisting concrete,
`thus resulting in the propagation ofcracks in thej oint between
`the old and new concrete.
`
`[0003] Other methods have been used to repair damaged
`concrete structures and to maintain the mechanical connec-
`
`tion between the new concrete section and a preexisting con-
`crete section. One prior art repair method involves first
`removing the damaged concrete and then drilling holes in the
`preexisting concrete using a rotary impact hammer drill.
`Thereafter, an adhesive is placed into the holes, and reinforc-
`ing bars are inserted such that the bars extend beyond the
`outer wall of the preexisting concrete and are generally per-
`pendicular to the joint between the preexisting concrete sec-
`tion and the gap defining the area where the new concrete is to
`be poured. The new concrete is then poured adjacently to the
`preexisting concrete such that the ends ofthe reinforcing bars
`extend into the new concrete and bond with the new concrete
`when the new concrete cures. As a result, when the new
`concrete cures, it will be joined to the preexisting concrete via
`the reinforcing bars. When attaching external fixtures to pre-
`existing concrete sections, holes are commonly drilled using
`a standard rotary drill, and the anchors are either bonded or
`friction-fitted within the drilled holes. The external fixtures
`are then mounted onto the anchors.
`
`Several disadvantages are associated with these past
`[0004]
`methods of repair and attachment of newly poured concrete.
`For instance, the drilling of multiple holes into the existing
`concrete is a slow and labor intensive process. Additionally,
`the vibrations associated with the drilling of the holes can
`cause an entire section of concrete to fail. Moreover, once a
`hole is drilled, it must be subsequently cleaned of dust and
`concrete particles in order to permit the adhesive to properly
`bond to the concrete. Furthermore, cracks can form over time
`in the joint between the new concrete section and the preex-
`isting concrete. As such, when moisture seeps down these
`cracks, the metallic reinforcing bars will rust, corrode, and
`subsequently fail, thereby necessitating further repair of the
`concrete section. Also, a phenomenon known in the industry
`as “burping” may occur, whereby air pockets become trapped
`within the hole once the reinforcing bar is installed, thereby
`
`preventing at least a portion of the adhesive from bonding
`with the reinforcing bar. Such defective bonding can lead to
`premature failure of the reinforced joint.
`[0005] The repair of concrete structures such as a parking
`garage structure, a concrete driveway or the like that is dis-
`posed above T—shaped concrete beams can be problematic.
`The concrete structures are typically joined together by metal
`clips. As cracks form in the concrete structures, moisture
`seeps into the concrete supports and corrodes the metal clips.
`Such metal clip corrosion ultimately causes the metal clip to
`fail, which can result in the collapsing of a concrete slab
`within the parking garage. One prior art method to repair this
`type of damage involves welding or bolting a supplemental
`joining apparatus to both supports, thereby retaining them
`together. This method is expensive and labor intensive. Addi-
`tionally, the repair is aesthetically unappealing. Another prior
`art method to repair this type of damage involves cutting
`through the concrete to access and replace the failed metal
`clip. Again, this process is labor intensive and expensive.
`[0006] Another prior art method to repair concrete struc-
`tures disposed above T—shaped concrete beams is disclosed in
`US. Pat. No. 6,312,541, which is incorporated herein by
`reference. The ’541 patent discloses the use of a half-moon
`shaped molded composite insert that is inserted into a cut slot
`in the concrete slab. The slot is cut generally perpendicular to
`the T—shaped concrete beams and across the gap between two
`concrete structures. An epoxy material is used to secure the
`composite insert in the cut slot. The composite insert includes
`a plurality of cavities that facilitate in the bonding of the
`composite insert within the cut slot in the concrete slab.
`Although the molded composite insert is an improvement
`over prior art methods to repair damaged concrete, there
`remains a continued need to improve the strength and dura-
`bility of the repaired concrete.
`
`SUMMARY OF THE INVENTION
`
`[0007] The present invention is directed to a method and
`apparatus for strengthening and repairing concrete connec-
`tions, and more particularly directed to a method and appa-
`ratus for repairing the flange-to-flange connections for pre-
`cast and prestressed double tee systems. The method or repair
`of the present invention includes the use of an improved
`composite material that is bonded to a damaged region of
`concrete. The method of repair of the present invention is
`simple to implement, generally less expensive than welding
`or bolting a supplemental joining apparatus to the damaged
`concrete, and only requires a small region about the damaged
`concrete to be closed down for repair, thus minimizing the
`need to close off the complete concrete structure during the
`repair process. This last advantage is beneficial to car garage
`owners since the method of repair of the present invention
`does not require the car garage to be closed or a level ofthe car
`garage to be closed while repairing the damaged regions of
`the car garage.
`[0008]
`In one non-limiting aspect of the present invention,
`the improved composite material includes a first fiber system
`that is coated, saturated or incorporated in a resin material.
`The composite material is designed to resist tensile loading
`and simple shear so as to facilitate in the repair of damaged
`concrete. The fibers included in composite material can
`include one or more types of fibers (e.g., carbon fibers, glass
`fibers aramid fibers [Kevlar, Twaron, etc.], boron fibers,
`hemp, basalt fibers, etc.). The first fiber system can include
`one or more layers of fibers. For example, the first fiber
`
`Metromont Ex-1007, p.7
`
`Metromont Ex-1007, p.7
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`

`

`US 2012/0073231 A1
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`Mar. 29, 2012
`
`system can be formed of a) a single layer of fibers, b) two or
`more layers of fibers that are oriented in a non-parallel rela-
`tionship to one another, c) one or more fabric layers wherein
`each fabric layer includes two or more layers of fibers that are
`oriented in a non-parallel relationship to one another and
`which fiber layers are woven or non-woven, and/or stitched
`together, heat bonded together, or otherwise connected
`together, or d) some combination of one or more fiber layers
`and one or more fabric layers. When two or more layers that
`form the first fiber system are included in the composite
`material, the adj acently positioned layers can be placed par-
`allel or nonparallel
`to one another. In one non-limiting
`embodiment of the invention,
`the composite material
`includes one or more layers of first fiber system or the aggre-
`gate fibers in the first fiber system have a tensile strength of at
`least about 50 KSI. The tensile strength is the maximum stress
`that the fiber can withstand before failure of the fiber. In one
`
`non-limiting aspect of this embodiment, the composite mate-
`rial includes one or more layers of first fiber system or the
`aggregate fibers in the first fiber system have a tensile strength
`of at least about 300 KSI. In another non-limiting aspect of
`this embodiment, the composite material includes one or
`more layers of first fiber system or the aggregate fibers in the
`first fiber system have a tensile strength of at least about 350
`KSI. In still another non-limiting aspect of this embodiment,
`the composite material includes one or more layers of first
`fiber system or the aggregate fibers in the first fiber system
`have a tensile strength of about 350-700 KSI. In yet another
`non-limiting aspect of this embodiment, the composite mate-
`rial includes one or more layers of first fiber system or the
`aggregate fibers in the first fiber system have a tensile strength
`of about 400-675 KSI. In another and/or alternative non-
`
`limiting embodiment ofthe invention, the composite material
`includes one or more layers of first fiber system or the aggre-
`gate fibers in the first fiber system have a tensile modulus of at
`least about 3 MSI. Tensile modulus is an indicator of the
`
`stiffness of the fiber. Tensile modulus is the applied stress on
`the fiber, based on force and cross-sectional area of the fiber,
`divided by the observed strain at such stress level. In one
`non-limiting aspect of this embodiment, the composite mate-
`rial includes one or more layers of first fiber system or the
`aggregate fibers in the first fiber system have a tensile modu-
`lus of at least about 10 MSI. In another non-limiting aspect of
`this embodiment, the composite material includes one or
`more layers of first fiber system or the aggregate fibers in the
`first fiber system have a tensile modulus of at least about 15
`MSI. In still another non-limiting aspect of this embodiment,
`the composite material includes one or more layers of first
`fiber system or the aggregate fibers in the first fiber system
`have a tensile modulus of about 15-50 MSI. In yet another
`non-limiting aspect of this embodiment, the composite mate-
`rial includes one or more layers of first fiber system or the
`aggregate fibers in the first fiber system have a tensile modu-
`lus of about 18-35 MSI. In one non-limiting example, the first
`fiber system includes one or more layers of carbon fibers or
`the aggregate fibers in the first fiber system have a tensile
`strength of about 400-640 KSI and a tensile modulus of about
`25-40 MSI. The resin material that is included in the compos-
`ite material generally includes vinyl ester resins, epoxy res-
`ins, polyester resins and/or phenolic resins. In one non-lim-
`iting embodiment ofthe invention, the resin material includes
`a vinyl ester resin. Generally the one or more layers of first
`fiber system are partially or fully impregnated with and/or
`saturated with the resin material.
`
`In another and/or alternative non-limiting aspect of
`[0009]
`the present
`invention,
`the improved composite material
`includes one or more inner layers of first fiber system sand-
`wiched between two or more outer layers of a second fiber
`system. The first and second fiber system can include the
`same or different material. In one non-limiting embodiment
`ofthe invention, the composite material includes one or more
`layers of a first fiber system that are partially or fully impreg-
`nated with and/or saturated with one or more types of resin
`material, and each side ofthe composite material includes one
`or more layers of a second fiber system. In one non-limiting
`aspect of this embodiment, the one or more types of resin
`material partially or fully secure the one or more layers of
`second fiber system to the composite material. In another
`and/or alternative non-limiting aspect of this embodiment, at
`least one layer ofthe first and second fiber systems are at least
`partially formed of different materials. In one non-limiting
`example, the first fiber system can be formed of a carbon fiber
`and/or aramid fiber material, and the second fiber system can
`be formed ofa glass fiber material. Generally, the second fiber
`system is selected to facilitate in the bonding ofthe composite
`material to a concrete structure to be repaired and to protect
`the one or more inner layers ofthe composite material, and the
`first fiber system is designed to enhance the strength of the
`composite material; however, this is not required.
`[0010]
`In still another and/or alternative non-limiting
`aspect of the present invention, the first fiber system in the
`improved composite material includes at least one fabric
`layer that includes two or more layers of fibers oriented in a
`nonparallel relationship to one another. The first fiber system
`can include more than one fabric layer; however, this is not
`required. As can be appreciated, the first fiber system can
`exclusively be formed of one or more fabric layers, or
`includes one or more fabric layers in combination with one or
`more fiber layers. The two or more layers of fibers that form
`the one or more fabric layers in the first fiber system are
`generally bonded and/or woven together prior to being
`impregnated and/or saturated with the resin material; how-
`ever, this is not required. In one non-limiting arrangement, the
`two or more layers of fibers that form the one or more fabric
`layers in the first fiber system are stitched together, heat
`bonded together and/or adhesively connected together. In
`another and/or alternative non-limiting arrangement, the two
`or more layers of fibers that form the one or more fabric layers
`in the first fiber system can be formed ofthe same or different
`fiber material. In still another and/or alternative non-limiting
`arrangement, at least one fabric layer in the first fiber system
`is formed of at least three fiber layers and the adjacently
`positioned fiber layers are oriented in a nonparallel relation-
`ship to one another. In one particular configuration, for each
`fiber layer in the first fiber system that runs in a plane non-
`parallel to the longitudinal axis of the first fiber system, the
`first fiber system includes a companion fiber layer that also
`runs in a plane non-parallel to the longitudinal axis ofthe first
`fiber system and at a negative angle (e.g., +45O & —45°, +30O
`& —30°, +60O & —60°, etc.). The volume of fibers used for
`each fiber layer in the one or more fabric layers used in the
`first fiber system can be the same or different. In one non-
`limiting design, the first fiber system includes one or more
`fabric layers, and at least one of the fabric layers is formed of
`three fiber layers, and wherein each fiber layer is formed of
`the same material and each fiber layer has the same volume
`and same number of fibers. In another non-limiting design,
`the first fiber system includes one or more fabric layers, and at
`
`Metromont Ex-1007, p.8
`
`Metromont Ex-1007, p.8
`
`

`

`US 2012/0073231 A1
`
`Mar. 29, 2012
`
`least one of the fabric layers is formed of three fiber layers,
`and wherein each fiber layer is formed of the same material,
`and a first fiber layer runs generally parallel to the longitudi-
`nal axis ofthe fabric layer and the second and third fiber layers
`run non-parallel to the longitudinal axis of the fabric layer,
`and the second and third fiber layers have the same volume
`and same number of fibers. In still another non-limiting
`design, the first fiber system includes one or more fabric
`layers, and at least one of the fabric layers is formed of three
`fiber layers, and wherein each fiber layer is formed of the
`same material, and a first fiber layer runs generally parallel to
`the longitudinal axis of the fabric layer and the second and
`third fiber layers run non-parallel to the longitudinal axis of
`the fabric layer, and the second and third fiber layers have the
`same volume and same number offibers, and the second layer
`runs at a positive angle A to the longitudinal axis ofthe fabric
`layer and the third layer runs at a negative angle A to the
`longitudinal axis of the fabric layer. In yet another non-lim-
`iting design, the first fiber system includes one or more fabric
`layers, and at least one of the fabric layers is formed of three
`carbon fiber layers that are stitched together, and a first fiber
`layer runs generally parallel to the longitudinal axis of the
`fabric layer and the second and third fiber layers run non-
`parallel to the longitudinal axis of the fabric layer, and the
`second and third fiber layers have the same volume and same
`number of fibers, and the second layer runs at a positive angle
`A to the longitudinal axis ofthe fabric layer and the third layer
`runs at a negative angleA to the longitudinal axis ofthe fabric
`layer.
`In still yet another and/or alternative non-limiting
`[0011]
`aspect of the present invention, the second fiber system in the
`improved composite material can be the same or different
`from the first fiber system. The second fiber system includes
`one or more layers of fibers. For example, the second fiber
`system can be formed of a) a single layer of fibers, b) two or
`more layers of fibers that are oriented in a non-parallel rela-
`tionship to one another, c) one or more fabric layers wherein
`each fabric layer includes two or more layers of fibers that are
`oriented in a non-parallel relationship to one another and
`which fiber layers are woven or non-woven, and/or stitched
`together, heat bonded together, or otherwise connected
`together, or d) some combination of one or more fiber layers
`and one or more fabric layers. When two or more layers that
`form the second fiber system are included in the composite
`material, the adj acently positioned layers can be placed par-
`allel or nonparallel
`to one another. In one non-limiting
`embodiment of the invention, the second fiber system is
`formed of at least one fabric layer that includes two or more
`layers of fibers oriented in a nonparallel relationship to one
`another; however, this is not required. The second fiber sys-
`tem can include more than one fabric layer; however, this is
`not required. As can be appreciated, the second fiber system
`can exclusively be formed of one or more fabric layers, or
`includes one or more fabric layers in combination with one or
`more fiber layers. The two or more layers of fibers that form
`the one or more fabric layers in the second fiber system are
`generally bonded and/or woven together prior to being
`impregnated and/or saturated with the resin material; how-
`ever, this is not required. In one non-limiting arrangement, the
`two or more layers of fibers that form the one or more fabric
`layers in the second fiber system are stitched together, heat
`bonded together and/or adhesively connected together. In still
`another and/or alternative non-limiting arrangement, the two
`or more layers of fibers that foil the one or more fabric layers
`
`in the second fiber system can be formed of the same or
`different fiber material. In another and/or alternative non-
`
`limiting arrangement, at least one fabric layer in the second
`fiber system is formed of at least three fiber layers and the
`adj acently positioned fiber layers are oriented in a nonparallel
`relationship to one another. In one particular configuration,
`for each fiber layer in the second fiber system that runs in a
`plane non-parallel to the longitudinal axis of the second fiber
`system, the second fiber system includes a companion fiber
`layer that also runs in a plane non-parallel to the longitudinal
`axis of the second fiber system and at a negative angle (e.g.,
`+45o & —45°, +30o & —30°, +60o & —60°, etc.). The volume
`of fibers used for each fiber layer in the one or more fabric
`layers used in the second fiber system can be the same or
`different. In one non-limiting design, the second fiber system
`includes one or more fabric layers, and at least one of the
`fabric layers is formed of three fiber layers, and wherein each
`fiber layer is formed of the same material and each fiber layer
`has the same volume and same number of fibers. In another
`
`non-limiting design, the second fiber system includes one or
`more fabric layers, and at least one of the fabric layers is
`formed of three fiber layers, and wherein each fiber layer is
`formed of the same material, and a first fiber layer runs
`generally parallel to the longitudinal axis of the fabric layer
`and the second and third fiber layers run non-parallel to the
`longitudinal axis of the fabric layer, and the second and third
`fiber layers have the same volume and same number of fibers.
`In still another non-limiting design, the second fiber system
`includes one or more fabric layers, and at least one of the
`fabric layers is formed of three fiber layers, and wherein each
`fiber layer is formed of the same material, and a first fiber
`layer runs generally parallel to the longitudinal axis of the
`fabric layer and the second and third fiber layers run non-
`parallel to the longitudinal axis of the fabric layer, and the
`second and third fiber layers have the same volume and same
`number of fibers, and the second layer runs at a positive angle
`A to the longitudinal axis ofthe fabric layer and the third layer
`runs at a negative angleA to the longitudinal axis ofthe fabric
`layer. In yet another non-limiting design, the second fiber
`system includes one or more fabric layers, and at least one of
`the fabric layers is formed of three glass fiber layers that are
`stitched together, and a first fiber layer runs generally parallel
`to the longitudinal axis of the fabric layer and the second and
`third fiber layers run non-parallel to the longitudinal axis of
`the fabric layer, and the second and third fiber layers have the
`same volume and same number offibers, and the second layer
`runs at a positive angleA to the longitudinal axis of the fabric
`layer and the third layer runs at a negative angle A to the
`longitudinal axis of the fabric layer. The tensile strength and/
`or tensile modulus of one or more fiber layers or all of the
`fibers layers in the second fiber system can be the same as or
`different to the tensile strength and/or tensile modulus of one
`or more fiber layers or all ofthe fibers in the first fiber system.
`In one non-limiting embodiment of the invention, the com-
`posite material includes one or more layers of second fiber
`system or the aggregate fibers in the second fiber system have
`a tensile strength of at least about 50 KSI. In one non-limiting
`aspect of this embodiment, the composite material includes
`one or more layers of second fiber system or the aggregate
`fibers in the second fiber system have a tensile strength of at
`least about 300 KSI. In another non-limiting aspect of this
`embodiment, the composite material includes one or more
`layers of second fiber system or the aggregate fibers in the
`second fiber system have a tensile strength of at least about
`
`Metromont Ex-1007, p.9
`
`Metromont Ex-1007, p.9
`
`

`

`US 2012/0073231 A1
`
`Mar. 29, 2012
`
`350 KSI. In still another non-limiting aspect of this embodi-
`ment, the composite material includes one or more layers of
`second fiber system or the aggregate fibers in the second fiber
`system have a tensile strength of about 350-700 KSI. In yet
`another non-limiting aspect ofthis embodiment, the compos-
`ite material includes one or more layers of second fiber sys-
`tem or the aggregate fibers in the second fiber system have a
`tensile strength of about 400-675 KSI. In another and/or
`alternative non-limiting embodiment of the invention, the
`composite material includes one or more layers of second
`fiber system or the aggregate fibers in the second fiber system
`have a tensile modulus of at least about 3 MSI. In one non-
`
`limiting aspect of this embodiment, the composite material
`includes one or more layers of second fiber system or the
`aggregate fibers in the second fiber system have a tensile
`modulus of at least about 5 MSI. In another non-limiting
`aspect of this embodiment, the composite material includes
`one or more layers of second fiber system or the aggregate
`fibers in the second fiber system have a tensile modulus of at
`least about 6 MSI. In still another non-limiting aspect of this
`embodiment, the composite material includes one or more
`layers of second fiber system or the aggregate fibers in the
`second fiber system have a tensile modulus of about 6-25
`MSI. In yet another non-limiting aspect of this embodiment,
`the composite material includes one or more layers of second
`fiber system or the aggregate fibers in the second fiber system
`have a tensile modulus of about 6-15 MSI. In one non-limit-
`
`ing example, the second fiber system includes one or more
`layers of glass fibers or the aggregate fibers in the second fiber
`system have a tensile strength of about 250-680 KSI and a
`tensile modulus of about 65-13 MSI. The resin material that
`
`is used to bond the second fiber system to the first fiber system
`generally includes Vinyl ester resins, epoxy resins, polyester
`resins and/or phenolic resins. In one non-limiting embodi-
`ment of the invention, the resin material includes a vinyl ester
`resin. Generally the one or more layers of the second fiber
`system are partially or fully impregnated with and/or satu-
`rated with the resin material.
`
`In another and/or alternative non-limiting aspect of
`[0012]
`the present
`invention,
`the improved composite material
`includes a first fiber system that includes one or more fabric
`layers and a second fiber system that includes one or more
`fabric layers secured by the resin material to at least one side
`ofthe fabric layer ofthe first fiber system. In one non-limiting
`embodiment of the invention, the improved composite mate-
`rial includes a first fiber system and a second fiber system that
`are connected together by a resin material. The second fiber
`system includes two fabric layers wherein one fabric layer of
`the second fiber system is connected to one side of the fabric
`layer ofthe first fiber system and the second fabric layer ofthe
`second fiber system is connected to the other side ofthe fabric
`layer ofthe first fiber system. In another non-limiting embodi-
`ment of the invention,
`the improved composite material
`includes a first fiber system and a second fiber system that are
`connected together by a resin material. The first fiber system
`includes two fabric layers. The first side of the two fabric
`layers of the first fiber system is connected together. The two
`fabric layers of the first fabric component have a similar size
`and shape and are generally symmetrically oriented together
`with one another. The second fiber system includes two fabric
`layers wherein one fabric layer of the second fiber system is
`connected to the second side of one of the fabric layers of the
`first fiber system and the second fabric layer of the second
`fiber system is connected to the second side ofthe other fabric
`
`layer of the first fiber system such that the two fabric layers of
`the first fiber system are sandwiched between the two fabric
`layers ofthe second fiber system. As can be appreciated, more
`than two fabric layers of the first fiber system can be sand-
`wiched between the two fabric layers of the second fiber
`system. As also or alternatively can be appreciated, more than
`one fabric layer of the second fiber system can be connected
`to a second side of a fabric layer of the first fiber system. The
`fabric layers of the first and second fiber systems can be
`connected together by stitching, adhesive, melt bonding, and/
`or use of one or more resin materials.
`
`In still another and/or alternative non-limiting
`[0013]
`aspect of the present invention, the improved composite
`material is formed by saturating and/or impregnating the first
`and second fiber systems with a resin material and then press-
`ing the first and second fiber systems together until the resin
`cures. A vacuum can optionally be applied during the press-
`ing and curing steps. The process for forming the composite
`material can be by a batch process or a continuous process.
`The resin material can be pre-applied and/or applied as the
`fiber components are brought together. The layer of the fiber
`components can be preformed; however, this is not required.
`[0014]
`In yet another and/or alternative non-limiting aspect
`ofthe present invention, the improved composite material has
`a certain size, shape and thickness to achieve the desired
`repair strength for the damaged concrete. In one non-limiting
`embodiment of the invention, the longitudinal length of the
`composite material is at least about 8 inches. The maximum
`longitudinal length is about 25 inches. When the length ofthe
`composite material is less than about 8 inches, the desired
`resistance to tensile loading and simple shear is generally not
`achieved. When the length of the composite material
`is
`greater than about 25 inches, little, if any, improvement in
`resistance to tensile loading and simple shear is noticed. The
`width or height of the composite material is selected to be
`generally less than the thickness of the concrete being
`repaired; however, this is not required. In one non-limiting
`embodiment, the height or depth of the composite material is
`at least about 2 inches. In one non-limiting aspect of this
`embodiment, the height or depth of the composite material is
`about 2-6 inches, and typically about 2.5-5 inches. The width
`or thickness ofthe composite material will vary depending on
`the thickness ofthe first fiber system and optional second fiber
`system. In one non-limiting embodiment, the thickness ofthe
`composite material is at least about 0.05 inches. In one non-
`limiting aspect of this embodiment, the thickness of the com-
`posite material is about 0.08-05 inches, and typically about
`0.1-0.3 inches. The thickness of the composite material can
`be uniform or vary. In one non-limiting aspect of the inven-
`tion, when the thickness varies, generally the middle portion
`of the composite material is thicker than the two end sections
`of the composite material. The shape of the composite mate-
`rial is generally selected to fit within a repair cut slot in the
`concrete. In one non-limiting aspect of the invention, the two
`side profiles of the composite material along the longitudinal
`length of the composite material can be generally square or
`rectangular. In another non-limiting aspect of the invention,
`the two side profiles of the composite material along the
`longitudinal length ofthe composite material have the top and
`bottom edges ofthe composite material in a generally parallel
`relationship to one another and one or both of the ends of the
`composite material includes a curve