REACTIVE REINFORCEMENT BAR

Abstract

A composite rebar, which may include a reactive surface coating for improvement of the performance of buildings, freeways, and other concrete structures or other structures using rebar, where increasing the life and safety as well as improving the lifetime cost of the structure is important. Leveraging manufacturing opportunities of composite materials with an understanding of the mechanical properties of geometric shapes improves the system strength and reliability at minimal extra cost.

Description

TECHNICAL FIELD OF THE PRESENT DISCLOSURE

The present disclosure relates to reinforcement bars and their use in structures. In particular, the present disclosure relates to the composition and geometry of reinforcement bars.

BACKGROUND OF THE PRESENT DISCLOSURE

Reinforcement bar, or rebar, is often used in construction to offer supplemental support to structures, and, commonly, structures formed of concrete. Largely made from recycled steel, the steel rebar material is subject to rust or oxidation which passivates the exterior in air, but decreases the adhesion in a concrete mix. Steel rebar relies on ridges rolled into the surface for mechanically locking into the concrete, without chemical adhesion or bonding. In building failures, the bumps can easily pull out of the concrete, demonstrating that the ultimate failure origin of steel rebar's low pullout strength should be addressed. The smooth nature of steel rebar and the lack of a chemical reaction between steel and concrete results in a pull-out strength equal to the force required to elongate or stretch the steel; the elongation of the rebar may result in the concrete formed between the ridges to crumble upon elongation of the steel rebar.

The surface of steel rebar is prone to iron oxide rust with any exposure to moisture from the air or direct contact with moisture, which acts as a lubricant for pulling the rebar from the concrete. Steel rebar relies on the alkali nature of cement to protect it from corrosion if a pH higher than 12 is maintained. However, if the cement is neutralized through carbon dioxide absorption or salt water instruction, over time, the steel rebar easily corrodes and can result in catastrophic failure of the structure, rather than reinforcement.

Corrosion of the rebar limits the pullout strength of the concrete, and it is difficult to assess any flaws or blemishes once the concrete is poured. Additionally, iron oxide rust resulting from steel may expand up to six times the original size, cracking the surrounding concrete and leading to failure. This failure is especially common when the structure is exposed to salt water, which reacts with the cement and decreases the strength of the concrete.

The components of seawater react chemically with the components of the cement in concrete, causing damage to the concrete structure in a number of ways. Magnesium sulfate in seawater reacts with the calcium hydroxide in cement to form calcium sulfate and magnesium hydroxide precipitate. Magnesium sulfate in seawater also reacts with hydrated calcium aluminate in cement to form calcium sulphoaluminate. These reactions result in the formation of ettringite, gypsum, and thaumasite, which lead to spalling, cracking, expansion, and a reduction in strength.

Leaching may further deteriorate concrete structures in the presence of seawater, especially in small concrete structures. Sulfates attack the concrete and cause expansion, but due to the presence of chlorides in seawater, the swelling of concrete is retarded. When magnesium dichloride transports in concrete, magnesium can precipitate as brucite, consuming the hydroxides and reducing the pH. This can lead to further decalcification of calcium silicate hydrate (CSH) or formation of magnesium silicate hydrate (MSH). As a result, erosion and loss of concrete may occur even without much expansion. This weakening and the chemical reactions that lower the alkali protection of the rebar both contribute to the eventual exposure of the rebar and rusting, causing failure.

SUMMARY OF THE DISCLOSURE

The present disclosure provides a composite rebar, which may include a reactive surface coating for improvement of the performance of buildings, freeways, and other concrete structures or other structures using rebar, where increasing the life and safety as well as improving the lifetime cost of the structure is important. Leveraging manufacturing opportunities of composite materials with an understanding of the mechanical properties of geometric shapes improves the system strength and reliability at minimal extra cost.

In a first aspect of the disclosure a section of reinforcement bar is disclosed. The section of reinforcement bar comprises an elongate member including a first rectangular face extending along a length of the elongate member and a second rectangular face opposite of the first rectangular face so that the first rectangular face and the second rectangular face are separated by an edge, the second rectangular face extending along the length of the elongate member.

In another aspect of the disclosure, a fastener is disclosed. The fastener comprises a first wing portion and a second wing portion connected to the first wing portion with a bridge portion. A length of the bridge portion defines a first gap between the first wing portion and the second wing portion.

In yet another aspect of the disclosure, a reinforcement bar structure is disclosed. The reinforcement bar structure comprises a first elongate section of reinforcement bar defining a first opening, a second elongate section of reinforcement bar defining a second opening aligned with the first opening, and a fastener positioned within the first opening and the second opening to couple the first elongate section with the second elongate section. The fastener comprises a first wing portion, a second wing portion connected to the first wing portion with a bridge portion, and a gap defined between the first wing portion and the second wing portion. The bridge portion is positioned within the first opening and the second opening so that the first wing is positioned on a first side of the first elongate section and the second elongate section and the second wing is positioned on a second side of the first elongate section and the second elongate section. A portion of the first elongate section and a portion of the second elongate section are positioned within the gap of the fastener.

In another aspect of the disclosure, a method of manufacturing a reinforcement bar is disclosed. The method comprises binding fibers together with a binding agent to form an elongate member; distributing a polymer binder on an exterior surface of the elongate member; dusting a reactive powder over the polymer binder and the elongate member; and rolling or compressing the reactive powder into the surface of the elongate member.

In various aspects of the disclosure, the section of reinforcement bar may further comprise a plurality of openings distributed along the length of the elongate member. Each opening of the plurality of openings may be configured to receive a second elongate member.

In various aspects of the disclosure, the elongate member may comprise a fiber reinforced polymer. The elongate member may comprise basalt reinforced fiber.

In various aspects of the disclosure, the elongate member may comprise steel.

In various aspects of the disclosure, the elongate member may be wrapped around a spool.

In various aspects of the disclosure, the section of reinforcement bar may further comprise a reactive powder coating fixedly attached to the elongate member. The reactive powder coating may comprise a pozzolan. The reactive powder coating may comprise at least one of clinker, cement, clay, and volcanic rock. The reactive powder coating may comprise at least one of fly ash, silica fume, rice husk ash, slag cement, and metakaolin. The reactive powder coating may be bound to the elongate member with a bonding agent. The bonding agent may be dicyclopentadiene. The bonding agent may be vitreous enamel coating.

In various aspects of the disclosure, the elongate member may define a preferred bending direction.

In various aspects of the disclosure, the length of the bridge portion may further define a second gap between the first wing portion and the second wing portion opposite the first gap.

In various aspects of the disclosure, the fastener may be symmetrical across a midpoint of the bridge portion in either the lateral direction or the longitudinal direction. The fastener may be symmetrical across a midpoint of the bridge portion in both the lateral direction and the longitudinal direction.

In various aspects of the disclosure, the fastener may be H-shaped.

In various aspects of the disclosure, a plurality of corners of the fastener may be rounded.

In various aspects of the disclosure, the gap may be configured to receive a section of rebar. The gap may be configured to receive a plurality of sections of rebar.

In various aspects of the disclosure, the first gap may be tapered in width between the bridge portion and a first end of the fastener.

In various aspects of the disclosure, the first elongate section and the second elongate section may each be sections of a common reinforcement bar.

In various aspects of the disclosure, the first elongate section may be a section of a first reinforcement bar and the second elongate section may be a section of a second reinforcement bar different from the first reinforcement bar.

In various aspects of the disclosure, at least one of the first elongate section and the second elongate section may include a reactive powder coating.

In various aspects of the disclosure, at least one of the first elongate section and the second elongate section may be rectangular in shape. At least one of the first elongate section and the second elongate section may be ribbon-shaped.

In various aspects of the disclosure, the reinforcement bar structure may be a cage.

In various aspects of the disclosure, the reinforcement bar structure may be a grid.

In various aspects of the disclosure, the reactive powder may comprise a pozzolan.

In various aspects of the disclosure, the elongate member may be rectangular.

In various aspects of the disclosure, the method may further comprise winding the elongate member onto a spool.

Additional features and advantages of the present disclosure will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiments exemplifying the disclosure as presently perceived.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description of the drawings particularly refers to the accompanying figures in which:

FIG. 1A illustrates a plan view of a rectangular reinforcement bar;

FIG. 1B illustrates a perspective view of the rectangular reinforcement bar of FIG. 1A;

FIG. 1C illustrates a side view of the rectangular reinforcement bar of FIG. 1A;

FIG. 2A illustrates a first exemplary cross-sectional shape of a reinforcement bar to demonstrate differences in shape characteristics between shapes having a similar area;

FIG. 2B illustrates a second exemplary cross-sectional shape of a reinforcement bar to demonstrate differences in shape characteristics between shapes having a similar area in view of FIG. 2A;

FIG. 2C illustrates a third exemplary cross-sectional shape of a reinforcement bar to demonstrate differences in shape characteristics between shapes having a similar area in view of FIGS. 2A and 2B;

FIG. 3A illustrates a first perspective view of a rectangular reinforcement bar formed in a circular shape and fastened to itself with a fastener to hold said circular shape;

FIG. 3B illustrates a second perspective view of a rectangular reinforcement bar formed in a circular shape ad fastened to itself with a fastener to hold said circular shape;

FIG. 4A illustrates a perspective view of a fastener for coupling sections of reinforcement bar;

FIG. 4B illustrates a plan view of the fastener of FIG. 4A;

FIG. 4C illustrates a side view of the fastener of FIG. 4A;

FIG. 5A illustrates a perspective view of another fastener for coupling sections of reinforcement bar;

FIG. 5B illustrates a plan view of the fastener of FIG. 5A;

FIG. 6 illustrates a plurality of sections of reinforcement bar having a reactive coating; and

FIG. 7 illustrates a method for forming a reinforcement bar having a reactive coating.

Although the drawings represent embodiments of various features and components according to the present disclosure, the exemplification set out herein illustrates an embodiment, and such an exemplification is not to be construed as limiting the scope of the disclosure in any manner.

DETAILED DESCRIPTION OF THE DRAWINGS

Reinforcement bar, commonly referred to as rebar, is often used in concrete construction to increase the tensile strength of concrete. Generally, concrete itself has a high compression strength, but a low tensile strength which allows concrete to crack and fail under tensile stress during, for example, earthquakes or transient loading where forces concentrate the load differently than the structure was designed to support. The use of rebar significantly increases the tensile strength of a corresponding concrete structure to mitigate cracking and provide a stronger building system.

In use, rebar may be used to create a reinforcement network within a concrete structure. Often, the reinforcement network may be a grid or cage formed of rebar, which works by distributing the load across a wider area than a single length of rebar alone. With the presence of a reinforcement network, when the corresponding concrete structure is placed under a tensile load, the reinforcement network distributes said tensile load and, due to the intermeshing of the reinforcement network with the concrete, transfers the tensile load into a distributed tensile and compressive load, which mitigates the cracks in the corresponding concrete structure due to the larger area and volume over which the load is spread.

Reinforcement networks—including but not limited to grids or cages formed of rebar—may be positioned throughout a corresponding concrete structure to facilitate an even distribution of the load. To form the reinforcement networks, the included rebar may be bent 90-180° from its original position to provide additional strength, e.g., when the potential load is such that a straight piece of rebar may be more easily pulled out of the corresponding composite structure. Reinforcement networks may be formed of multiple pieces of interlaced rebar or may require significant reshaping of rebar to create complex structures in forming reinforcement networks. The multiple pieces of interlaced rebar may be wired or bound together to create the reinforcement network structure.

Rebar may be formed of steel, polymer, enamel or zinc coated steel, or stainless steel. In some embodiments, fiber reinforced polymer (“FRP”) rebar may be formed, via pultrusion, of carbon fiber, basalt fiber, or fiberglass and a polymer for holding said fibers together. Using a pultrusion process for manufacturing of fiber rebar may facilitate the coating of said rebar, including, for example, sand, aluminum oxide, or a pozzolan as discussed further herein. Additionally, FRP rebar includes materials that do not corrode within concrete or when exposed to the elements. In some embodiments, rebar may be formed of a hybrid of steel and at least one fiber reinforced polymer.

Rebar may be formed in a long shape having a circular cross-section with a varying diameter according to the desired use of the rebar. For example, the class of rebar refers to the number of ⅛″ increments in the diameter of the rebar; i.e. #4 rebar has a 4/8″ or ½″ diameter. Common rebar sizes include #3, #4, and #5 rebar for smaller concrete structures, while #8 rebar is commonly used in larger structures, including large buildings, bridges, freeways, footings, columns, beams, slabs, shear walls, or other constructs requiring a greater tensile strength. In some embodiments, as described further herein, rebar may have a cross-section in varying shapes, including ellipse, rectangle, square, triangular, or other shapes.

Referring to FIGS. 1A-1C a section of reinforcement bar, e.g., elongate member 100, is illustrated. As shown in FIG. 1C, elongate member 100 may have a thin, rectangular cross-section 102 resulting in a first rectangular face 104 opposite a second rectangular face 106 with a first edge 108 and a second edge 110 therebetween along a length L of the rebar 100. Openings 112 may be defined along the length L of the rebar 100 to receive a fastener to facilitate reshaping and holding of said shape of the rebar as described further herein. Openings 112 may be impressed or cut within the elongate member 100 during manufacturing. In other embodiments, other methods may be used to form openings 112, including the use of molds or tools.

The rectangular shape of the rebar 100 may allow for a similar or identical volume or cross-sectional area to supply the equivalent load of a circular rebar of a similar area as discussed above, assuming same materials, while providing a greater surface area of said rebar 100. For example, as noted above, #4 rebar has a ½″ diameter, or a ¼″ radius. The equation for calculating the area of a circle is:

A=πr ²

Therefore, the area of a cross-section of #4 circular rebar is 0.196 in². As such, a piece of rebar having a shape similar of that to rebar 100 as illustrated in FIGS. 1A-1C with a cross-section area of 0.196 in² would be considered as #4 rebar, despite the rectangular cross-section rather than a circular cross-section. In other words, #4 rebar having a circular cross-section and #4 rebar having a rectangular cross-section, where both are made of the same materials, provides equivalent strength.

Referring now to FIGS. 2A-2C, a circle 2, ellipse 3, and a rectangle 4 are provided, wherein each of the circle 2, the ellipse 3, and the rectangle 4 have similar areas. As illustrated, rectangle 4 has a width of 3 units and a length of 16.7 units, equating an area of 50.1 units²; ellipse 3 has a length of 15 units and a width of ˜2.3 units, equating an area of 50.58 units²; and circle 2 has a diameter of 8 units, equating an area of 50.3 units². Because tensile strength is proportional to cross-sectional area, a rebar section having a cross-section consistent with circle 2 and a rebar section having a cross-section consistent with rectangle 4 will have similar tensile strength.

However, the difference in shape results in a difference in surface area. The equation for calculating surface area of a cylindrical rebar section (i.e., a section of rebar with a circular cross-section) is:

$A=2\pi r^2+2\pi \mathrm{rh}$

where r is the radius of the cross-section and h is the height of the section of rebar.

The equation for calculating surface area of a rectangular rebar section (i.e., a section of rebar with a rectangular cross-section) is:

$A=2\left(\mathrm{wl}+\mathrm{hl}+\mathrm{hw}\right)$

where w is the width of the cross-section, l is the length of the cross-section, and h is the height of the section of rebar.

The equation for calculating surface area of an elliptical rebar section (i.e., a section of rebar with an elliptical cross-section) is:

$A=\left(P*h\right)+2\left(\mathrm{ab}\pi \right)$

where P is the perimeter of the cross-section, a is the radius of the major axis of the cross-section, b is the radius of the minor axis of the cross section, and h is the height of the section of rebar.

For example, a section of rebar having a cross-section consistent with rectangle 4 would have a surface area of 100.2+(39.4×Height) units², while a section of rebar having a cross-section consistent with circle 2 would have a surface area of 100.6+(25.1×Height) units². In FIG. 2B, it is given that the perimeter of the cross-section of ellipse 3 is 32.14, so that a section of rebar having a cross-section consistent with 101.16+(32.14×Height) units².

In other words, if a section of rebar has a height of 2 units and a cross-section consistent with rectangle 4, said section of rebar would have a surface area of 179 units². In another embodiment, if a section of rebar has a height of 2 units and a cross-section consistent with ellipse 3, said section of rebar would have a surface area of 165.44 units². In yet another embodiment, if a section of rebar has a height of 2 units and a cross-section consistent with circle 2, said section of rebar would have a surface area of 150.8. As such, the rectangular and elliptical rebar sections each have greater tensile strength compared to the circular rebar section, despite having similar cross-sectional areas.

Additionally, the differing shapes result in differing bending moments. For example, the thin, ribbon-like shape of elongate member 100 illustrated in FIGS. 1A-1C may require less force to bend toward a direction transverse to the plane in which either of first rectangular face 104 or second rectangular face 106 lay than the thicker shape of conventional circular rebar. In other words, a ribbon-shaped rebar, or a section of rebar having a greater cross-sectional length than width, generally requires less bending force for shaping of the rebar as described further herein, including when compared to rectangular-shaped rebar having similar cross-sectional lengths and widths.

Fiber reinforced polymer rebar, e.g., rebar including carbon, basalt, and glass fibers, may provide a greater amount of strength at a lesser cross-sectional area. For example, in rebar sections having a circular cross-section, a basalt fiber rebar having a 1″ diameter (#8 rebar) has about twice the strength of a steel rebar having a 1½″ diameter (#12 rebar). Although basalt fiber rebar is referred to specifically herein, it is within the scope of the disclosure that fiber reinforced polymer rebar may comprise carbon, basalt, and/or glass fibers, as well as other fiber types as known in the art.

As discussed above, rebar may be applied to concrete to distribute tensile load, stress, and/or strain. Concrete has a specific tensile strength of 2-5 MPa, steel rebar has a tensile strength of about 500 MPa, and basalt fiber has a tensile strength of about 4800 MPa. While the addition of epoxy or polymer binder used to shape the basalt fiber and epoxy or polymer composite may reduce the strength advantage of basalt fiber rebar, such a reduction merely reduces the strength advantage to about three to four times relative to steel (i.e., 1500-2000 MPa).

In addition to providing a greater tensile strength at a lesser cross-sectional area, fiber reinforced polymer rebar, such as basalt fiber rebar, results in ten times lower CO₂ emissions and eight times lower energy requirements relative to steel rebar. Additionally, fiber reinforced polymer rebar, such as basalt fiber rebar, may not spall due to moisture intrusion, as compared to steel, which rusts and expands up to five times in volume under wet conditions. Additionally, basalt fiber rebar has a coefficient of thermal expansion similar to that of concrete, mitigating issues related to thermal mismatch.

Fiber reinforced polymer rebar, including basalt fiber rebar, may comprise of bundles of a plurality of fibers which are about 10-20 μm in diameter. The fibers within the rebar are flexible, facilitating absorption of shock and impact, swaying of concrete structures with wind load, and absorption of vibrations or deflections of concrete structures. Bundling several of the fibers within an epoxy or polymer matrix mitigates risks of cracking or failure in response to shear stress.

Despite the advantages presented above related to fiber reinforced polymer rebar and/or other composite rebars, the advantages presented herein related to the shape of rebar and/or rebar coatings also apply to conventional steel or other metal rebar sections. In other words, such applications of shape and/or rebar coatings as described further herein may also be applied to metal rebar.

Now referring to FIGS. 3A-3B, a shaped section of rebar, e.g., elongate member 100 is illustrated. Elongate member 100 of FIGS. 3A-3B includes the same characteristics described in FIGS. 1A-1C and, additionally, is comprised of fiber reinforced polymer rebar, such as basalt fiber rebar. In view of the strength advantage as discussed above, elongate member 100 may be formed in a ribbon-like form without sacrificing strength, relative to steel rebar, which facilitates a lower bending moment so that the elongate member 100 may be easily shaped as illustrated or in other shapes, including cages or grid structures as discussed above.

In some embodiments, elongate member 100 may be manufactured in a spool for transportation purposes so that a user may unspool and cut sections of rebar in a customized manner for each use. The custom cut sections of elongate member 100 may then be shaped, if necessary, as needed immediately at the job site, including bending said sections up to at least 90° from the initial position of the section. This further allows for a user to create longer sections of rebar that do not have to be mechanically joined or welded together, as the sections are formed on demand rather than at a remote site before being transported. The flexibility of elongate member 100 further allows each section to be twisted along the longitudinal axis of the rebar section during application, increasing the pull-out strength of the rebar and distributing and redirecting applied tensile load into compressive load along the twist.

As shown in FIGS. 3A-3B, elongate member 100 may include openings 112 at intervals to receive a fastener 114, illustrated further in FIGS. 4A-4C and discussed further herein. Openings 112 may otherwise be shaped and sized to receive a second elongate member, i.e., a second section of rebar may be inserted into and/or through an opening 112 defined by a first section of rebar in a generally transverse direction relative to the first section of rebar. Such an arrangement may facilitate the creation of cages or grids of rebar as discussed above. In embodiments including a fastener 114, such fastener may include the fastener illustrated in FIGS. 4A-4C or may include another fastener capable of joining at least two sections of rebar together or, in some embodiments, coupling a section of rebar to itself to form an enclosed shape as illustrated in FIGS. 3A-3B.

Referring to FIGS. 4A-4C, fastener 114 may be a generally symmetrical shape having a first wing section 116 and a second wing section 118 separated by a bridge section 120. The length of bridge section 120 may define the width of a first gap 122 and a second gap 124 between first wing section 116 and second wing section 118 above and below bridge section 120. The width of the first gap 122 and/or the second gap 124 may correlate with the thickness of a rebar section consistent with rebar 100 discussed above. Additionally, fastener 114 may have a thickness consistent with or less than the width of an opening of the corresponding rebar section and/or a height consistent with or less than the length of an opening of the corresponding rebar section to facilitate insertion of the fastener 114 within opening 112 as discussed further herein. In some embodiments, the first gap 122 and/or the second gap 124 may correlate with the thickness of two or more rebar sections so that two or more rebar sections may be received within the first gap 122 and/or the second gap 124. While first wing section 116 and second wing section 118 are illustrated as having generally rounded corners 126, other embodiments may include squared corners or corners having other general shapes.

As illustrated in FIGS. 4A-4C, first gap 122 and second gap 124 may have generally consistent widths between first wing section 116 and second wing section 118. In other words, first gap 122 may have a generally consistent width from bridge portion 120 of fastener 114 to a first end 123 of fastener 114, while second gap 124 may have a generally consistent width from bridge portion 120 of fastener 114 to a second end 125 of fastener 114. The width of first gap 122 may greater, smaller, or substantially the same compared to the width of second gap 124.

In other embodiments, as illustrated in FIGS. 5A-5B, a fastener 214 may be generally consistent with and include the characteristics of fastener 114 except as described further herein, with like components having like reference numbers beginning with a “2” rather than a “1”.

Fastener 214 may include a first gap 222 and a second gap 224, each extending between a first wing section 216 and a second wing section 218, with first gap 222 and second gap 224 being separated by a bridge section 220. First gap 222 and second gap 224 may each have tapered widths defined by first wing section 216 and second wing section 218.

In other words, the width of first gap 222 may be smaller adjacent to bridge portion 220 compared to the width of first gap 222 adjacent to a first end 223 of fastener 214. Likewise, the width of second gap 224 may be smaller adjacent to bridge portion 220 compared to the width of second gap 224 adjacent to a second end 225 of fastener 214. Such tapered shapes may facilitate tightening of fastener 214 as applied to a section of rebar as described further herein.

In such embodiments, fastener 214 may maintain a generally symmetrical shape. In other embodiments, fastener 214 may not be symmetrical. For example, the tapering of widths of first gap 222 and second gap 224 may be inverted relative to each other or may not be otherwise symmetrical.

Referring again to FIGS. 3A-3B, a first opening 112 and a second opening 112 may generally be aligned to receive a fastener 114, 214 therethrough. The first opening 112 and the second opening 112 may be openings on a common section of rebar, such as elongate member 100 as illustrated. In other embodiments, the first opening 112 may be defined by a first section of rebar, while the second opening 112 may be defined on a second section of rebar separate from the first section of rebar.

Once the first opening 112 and the second opening 112 are aligned, a first wing section 116, 216 (FIGS. 4A, 5A) may be inserted through both of the first opening 112 and the second opening 112 so that a first edge portion 128 and a second edge portion 130 adjacent to the first opening 112 and a first edge portion 128 and a second edge portion 130 adjacent to the second opening 112 are aligned with a bridge portion 120, 220 (FIGS. 4A, 5A) of the fastener 114, 214.

The fastener 114, 214 may then be turned toward 90° so that the first edge portion 128 adjacent to the first opening 112 and the first edge portion 128 adjacent to the second opening 112 are received within the first gap 122, 222 (FIGS. 4A, 5A) of the fastener 114, 214, and the second edge portion 130 adjacent to the first opening 112 and the second edge portion 130 adjacent to the second opening 112 may be received within the second gap 124, 224 (FIGS. 4A, 5A) of the fastener 114, 214.

In some embodiments, a first opening 112 on a first section of rebar and a second opening 112 on a second section of rebar may be aligned by being placed in a plus or “T” shape so that the first opening 112 is generally transverse to the second opening 112 and, therefore, the first section of rebar is generally transverse to the second section of rebar. In such embodiments, fastener 114, 214 may be generally sized to be received within the aligned portions of the first opening 112 and the second opening 112. Alternatively or additionally, first opening 112 may be positioned laterally relative to the first section of rebar while the second opening 112 may be positioned longitudinally relative to the second section of rebar so that the first opening 112 and the second opening 112 are substantially fully aligned rather than transverse to one another, while the first section of rebar is positioned generally transverse to the second section of rebar.

In such a transverse arrangement, once the first opening 112 and the second opening 112 are aligned, a first wing section 116, 216 may be inserted through both of the first opening 112 and the second opening 112 so that a first edge portion 128 and a second edge portion 130 adjacent to the first opening 112 and a first edge portion 128 and a second edge portion 130 adjacent to the second opening 112 are aligned with a bridge portion 120, 220 (FIG. 4A, 5A) of the fastener 114, 214.

The fastener 114, 214 may then be turned toward 45° so that the first edge portion 128 adjacent to the first opening 112 and the first edge portion 128 adjacent to the second opening 112 are received within the first gap 122, 222 (FIG. 4A, 5A) of the fastener 114, 214, and the second edge portion 130 adjacent to the first opening 112 and the second edge portion 130 adjacent to the second opening 112 may be received within the second gap 124, 224, (FIG. 4A, 5A) of the fastener 114, 214.

Now referring to FIG. 6, elongate member 100 may include a coating 132 to facilitate bonding of the elongate member 100 to surrounding concrete when in use. Coating 132 may be a reactive powder coating comprising clinker, cement, clay, volcanic rock, or another base coating, and/or a pozzolan, including, for example, fly ash, silica fume, rice husk ash, slag cement, metakaolin, and or another pozzolan as known in the art.

Coating 132 may be applied to underlying elongate member 100 in a manner that results in the coating 132 being integrated with the elongate member 100 via, e.g., chemical bonding and/or embedding of the coating 100 within a surface layer of the elongate member 100.

For example, referring to the method 150FIG. 7, at box 152, an elongate member, e.g., rebar, may formed by binding fibers together using a bonding agent, such as dicyclopentadiene or another resin or bonding agent known in the art, to form a bar or strip as discussed above. The finished product may be a generally smooth, pultruded form. At box 154, the elongate member is sprayed with a resin, vitreous enamel, epoxy, or another polymer binder. Then, at box 156, the coating described above may be dusted over the sprayed elongate member and rolled into or compressed into the surface layer of the elongate member, binding to the elongate member via catalysis of the polymer binder described above. In some embodiments, glass frit may be melted to bind the coating to the elongate member.

When the coated rebar 100 is embedded within concrete during use, the pozzolan coating creates a chemical bond with the surrounding cement, improving the pull-out strength of the rebar. For example, silica or silica and aluminum in the pozzolan of the pozzolan coating will chemically react with calcium hydroxide of the cement and moisture to form compounds having similar properties to cement. As such, the rebar is truly embedded within the concrete as a result of the pozzolan embedded within the rebar also forming a cementitious relationship with the surrounding concrete. The rectangular cross-section of the rebar 100 as discussed above may further provides a greater surface area to which the coating 132 can bond, creating a greater pull-out strength.

Coating 132 may be applied to a fiber reinforced polymer rebar, such as basalt rebar, as discussed above or to conventional steel rebar coated with resin and the pozzolan mixture described above to improve pull-out strength. While coating 132 is described in conjunction with rectangular elongate member 100, coating 132 may be applied to rebar having a circular or elliptical cross section, or rebar having any cross-sectional shape.

While the system and methods herein have been described by reference to various specific embodiments it should be understood that numerous changes may be made within the spirit and scope of the concepts described, accordingly, it is intended that the invention is not limited to the described embodiments but will have full scope defined by the language of the following claims.

Claims

1. A section of reinforcement bar, comprising: an elongate member including a first rectangular face extending along a length of the elongate member and a second rectangular face opposite of the first rectangular face so that the first rectangular face and the second rectangular face are separated by an edge, the second rectangular face extending along the length of the elongate member.

2. The section of reinforcement bar of claim 1, further comprising a plurality of openings distributed along the length of the elongate member.

3. The section of reinforcement bar of claim 2, wherein each opening of the plurality of openings is configured to receive a second elongate member.

4. The section of reinforcement bar of claim 1, wherein the elongate member comprises a fiber reinforced polymer.

5. The section of reinforcement bar of claim 4, wherein the elongate member comprises basalt reinforced fiber.

6. The section of reinforcement bar of claim 1, wherein the elongate member comprises steel.

7. The section of reinforcement bar of claim 1, wherein the elongate member is wrapped around a spool.

8. The section of reinforcement bar of claim 1, further comprising a reactive powder coating fixedly attached to the elongate member.

9. The section of reinforcement bar of claim 8, wherein the reactive powder coating comprises a pozzolan.

10. The section of reinforcement bar of claim 9, wherein the reactive powder coating comprises at least one of clinker, cement, clay, and volcanic rock.

11. The section of reinforcement bar of claim 9, wherein the reactive powder coating comprises at least one of fly ash, silica fume, rice husk ash, slag cement, and metakaolin.

12. The section of reinforcement bar of claim 9, wherein the reactive powder coating is bound to the elongate member with a bonding agent.

13. The section of reinforcement bar of claim 12, wherein the bonding agent is dicyclopentadiene.

14. The section of reinforcement bar of claim 12, wherein the bonding agent is vitreous enamel coating.

15. The section of reinforcement bar of claim 1, wherein the elongate member defines a preferred bending direction.

16. A fastener, comprising: a first wing portion and a second wing portion connected to the first wing portion with a bridge portion;wherein a length of the bridge portion defines a first gap between the first wing portion and the second wing portion.

17. The fastener of claim 16, wherein the length of the bridge portion further defines a second gap between the first wing portion and the second wing portion opposite the first gap.

18. The fastener of claim 16, wherein the fastener is symmetrical across a midpoint of the bridge portion in either the lateral direction or the longitudinal direction.

19. The fastener of claim 18, wherein the fastener is symmetrical across a midpoint of the bridge portion in both the lateral direction and the longitudinal direction.

20. The fastener of claim 16, wherein the fastener is H-shaped.

21. The fastener of claim 16, wherein a plurality of corners of the fastener is rounded.

22. The fastener of claim 16, wherein the first gap is configured to receive a section of rebar.

23. The fastener of claim 22, wherein the first gap is configured to receive a plurality of sections of rebar.

24. The fastener of claim 16, wherein the first gap is tapered in width between the bridge portion and a first end of the fastener.

25. A reinforcement bar structure, comprising: a first elongate section of reinforcement bar defining a first opening;a second elongate section of reinforcement bar defining a second opening aligned with the first opening; anda fastener positioned within the first opening and the second opening to couple the first elongate section with the second elongate section, the fastener comprising: a first wing portion and a second wing portion connected to the first wing portion with a bridge portion, a gap defined between the first wing portion and the second wing portion;the bridge portion positioned within the first opening and the second opening so that the first wing is positioned on a first side of the first elongate section and the second elongate section and the second wing is positioned on a second side of the first elongate section and the second elongate section; anda portion of the first elongate section and a portion of the second elongate section are positioned within the gap of the fastener.

26. The reinforcement bar structure of claim 25, wherein the first elongate section and the second elongate section are each sections of a common reinforcement bar.

27. The reinforcement bar structure of claim 25, wherein the first elongate section is a section of a first reinforcement bar and the second elongate section is a section of a second reinforcement bar different than the first reinforcement bar.

28. The reinforcement bar structure of claim 25, wherein at least one of the first elongate section and the second elongate section includes a reactive powder coating.

29. The reinforcement bar structure of claim 25, wherein at least one of the first elongate section and the second elongate section is rectangular in shape.

30. The reinforcement bar structure of claim 29, wherein the at least one of the first elongate section and the second elongate section is ribbon-shaped.

31. The reinforcement bar structure of claim 25, wherein the reinforcement bar structure is a cage.

32. The reinforcement bar structure of claim 25, wherein the reinforcement bar structure is a grid.

33. A method of manufacturing a reinforcement bar, comprising: binding fibers together with a binding agent to form an elongate member;distributing a polymer binder on an exterior surface of the elongate member;dusting a reactive powder over the polymer binder and the elongate member; androlling or compressing the reactive powder into the surface of the elongate member.

34. The method of claim 33, wherein the reactive powder comprises a pozzolan.

35. The method of claim 33, wherein the elongate member is rectangular.

36. The method of claim 33, further comprising winding the elongate member onto a spool.