Basalt Basket and Dowel and Method of Manufacture

Abstract

Basalt basket and dowel system to provide load transfer between adjoining slabs. The basket is designed as a placement jig to properly position dowels during the concrete placement phase of construction. Additionally to provide inherently tinsel and shear reinforcement to the edge of the concrete before during and after the contraction stress of curing concrete is relieved by scoring and to do so without the risk of rust spalling. The baskets and dowels are constructed from continuous basalt fibers admixed with an appropriate adhesive to produce the required strength and provide load predictions in a similar manner to steel calculations. The basalt basket is light weight and the configuration of its tendons interlaces provides sufficient space to allow concrete flow during placement and too prevent tinsel slippage within the cured concrete.

Description

FIELD OF THE INVENTION

This invention relates to concrete reinforcement, and more particularly, to a basket and dowel reinforcement members made from continuous basalt fibers for use in load transfer between adjoining slabs.

BACKGROUND OF THE INVENTION

Due to constant expanding and contracting of concrete used in the formation of highways, joints are placed between slabs of concrete to absorb the movement. Between temperature fluctuations and heavy truck traffic, the concrete must be able to absorb movement without shifting or cracking. Construction techniques employ the use of dowel bars embedded in the concrete to transfer the load across the joints. The dowel bars reduce pavement roughness caused by faulting and improve the pavement's performance. Critical to the installation is that the dowel bars are placed in proper three-dimensional alignment. Misplaced or misaligned dowel bars can adversely affect the performance of the concrete. Misaligned dowel bars can lock up the joints and prevent them from opening and closing freely resulting in spalling, faulting, pumping, corner breaks, blowups, and mid-panel cracking. Because of the difficulties in determining the position of dowel bars in hardened concrete, misplaced dowel bars went largely undetected in the past, until it was too late and problems started to develop.

Most jointed concrete pavement failures can be attributed to failures at the joint, as opposed to inadequate structural capacity. The most common types of pavement joints, which are defined by their function, are as follows: (1) Longitudinal Joint—a joint between two slabs which allows slab warping without appreciable separation or cracking of the slabs; (2) Construction Joint—a joint between slabs that results when concrete is placed at different times. This type of joint can be further broken down into transverse and longitudinal joints; (3) Expansion Joint—a joint placed at a specific location to allow the pavement to expand without damaging adjacent structures or the pavement itself; and (4) Transverse Contraction Joint is a sawed, formed, or tooled groove in a concrete slab that creates a weakened vertical plane. It regulates the location of the cracking caused by dimensional changes in the slab, and is by far the most common type of joint in concrete pavements.

The primary purpose of transverse contraction joints is to control the cracking that results from the tensile and bending stresses in concrete slabs caused by the cement hydration process, traffic loadings, and the environment. Because these joints are so numerous, their performance significantly impacts pavement performance. The sawing of transverse contraction and longitudinal joints is intended to cause the pavement to crack at the intended joint. It should be made to a required depth and width. Joint spacing varies throughout the country because of considerations of initial costs, type of slab (reinforced or plain), type of load transfer, and local conditions. The amount of longitudinal slab movement that a joint experiences is primarily a function of joint spacing and temperature changes. Expansion characteristics of the aggregates used in the concrete and the friction between the bottom of the slab and the base also have an effect on slab movement. Good design and maintenance of contraction joints have virtually eliminated the need for expansion joints, except at fixed objects such as structures. When expansion joints are used, the pavement moves to close the unrestrained expansion joint over a period of a few years. As this happens, several of the adjoining contraction joints may open, effectively destroying their seals and aggregate interlock.

What is disclosed is an improved dowel system with positioning baskets that is light in weight, non-corroding, and better capable of maintaining dowel alignment by resisting deformation.

SUMMARY OF THE INVENTION

In light of the above and according to one aspect of the invention, disclosed herein is a basalt basket for positioning of dowels to provide improved loading between adjoining concrete slabs.

An objective of the present invention is to provide a continuous basalt fiber material matrix configuration that is an economical and sustainable alternative to steel dowel and basket construction, the basalt basket capable of securely holding dowels in alignment even if struck during the concrete pouring step.

Another objective of the present invention is to provide a dowel and basket system that cannot rust like steel which otherwise can absorb or wick water into the concrete.

Another objective of the present invention is to eliminate the dangerous position of cutting a steel basket that is under a load, the result of which can cause injury to the individual making the cut or cause the shifting of a dowel.

Still another objective of the present invention is to provide a continuous basalt fiber material that is stronger than steel when used in the basket configuration, has no memory of bending damage, does not need shipping ties to be cut before paving and is capable of maintaining shape if improperly stored before use.

Yet still another objective of the present invention is to provide a basalt matrix reinforcement system which is relatively light thereby reducing shipping cost, logistics issues, and installation stress by providing an easy to move configuration that can be carried by a single individual.

Yet another objective of the present invention is to provide a concrete reinforcement matrix that has the same thermal coefficient of expansion as concrete and is naturally resistant to corrosion, rust, alkali, and acids.

Still yet another objective of the present invention is to provide a concrete reinforcement matrix that does not conduct electricity and will not create a path for water to penetrate through the concrete.

Still yet another objective of the present invention is to provide a concrete reinforcement matrix that does not allow the creation of magnetic fields.

Still yet another objective of the present invention is to eliminate radar reflection, the blockage of radio waves, microwaves, and thus permit improved thermo scans results.

Yet another objective of the present invention is to extend the service limits of thermal load limits of a concrete structure.

Yet still another objective of the present invention is to provide a concrete reinforcement matrix that can be cut with a conventional saw.

Another objective of the present invention is to provide a continuous matrix basket configuration that can be made of basalt, fiberglass, carbon fiber, or the use of bio fibers such as hemp, the basket capable of securely holding dowels made of basalt, fiberglass, carbon fiber or steel in alignment even if struck during the concrete pouring step.

Other objectives and further advantages and benefits associated with the basalt rebar matrix will be apparent to those skilled in the art from the description, examples and claims which follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a 1½″, 1¼″ and a polygon shaped 12″ dowel;

FIG. 2 illustrates a 1½″, 1¼″ and a polygon shaped 18″ dowel;

FIG. 3 is a side view of the basalt basket;

FIG. 4 is a perspective view of the basalt basket;

FIG. 5 is a side view of a basalt basket holding a dowel;

FIG. 6 is a perspective view of a basalt basket holding dowels;

FIG. 7 is a perspective view of two rows of basalt baskets holding dowels;

FIG. 8 is a side view of the basalt basket illustrating wheel loading;

FIG. 9 is a perspective view of a basket forming base device;

FIG. 10 is a perspective view of a basket forming base device with alignment pins;

FIG. 11 is a side view of a basket forming base device with a formed basalt basket;

FIG. 12 is a top view of an alternative basalt basket embodiment holding dowels;

FIG. 13 is a side view of the alternative basalt basket embodiment of FIG. 12;

FIG. 14 is an end view of the alternative basalt basket embodiment of FIG. 12 with a dowel;

FIG. 15 is a perspective view of the alternative basalt basket embodiment of FIG. 12 with dowels;

FIG. 16 is a perspective view of an alternative embodiment basket forming base; and

FIG. 17 is a side view of the alternative embodiment basket forming base of FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The purpose of the dowels is to transfer loads across a joint without restricting joint movement due to thermal contraction and expansion of the concrete. Studies have shown that larger dowels are more effective in transferring loads and in reducing faulting. Dowels should be corrosion-resistant to prevent dowel seizure, which causes the joint to lock up. Epoxy-coated and stainless steel dowels have been shown to adequately prevent corrosion. Smooth dowels are the most widely used method of transferring load across expansion joints. Expansion joint dowels are specially fabricated with a cap on one end of each dowel that creates a void in the slab to accommodate the dowel as the adjacent slab closes the expansion joint.

Dowel baskets are used to ensure that the dowels are properly aligned. Conventional dowel baskets are constructed from steel, are about 24″×12′ in dimension. A steel dowel basket weighs about 50 lbs and a steel dowel that is about 1½″×24″ weigh about 20 lbs. The weight of the steel basket limits how many can be stacked for storage and shipping without causing deformation of the baskets and related tolerances. Further, an individual could only be expected to carry a single steel basket due to the weight. During installation, dowels are lightly coated with grease or other substance over their entire length to prevent bonding of the dowel to the concrete. Coating only one-half of the dowel has frequently resulted in problems, primarily caused by insufficient greasing and/or dowel misalignment. The dowel must be free to slide in the concrete so that the two pavement slabs move independently, thus preventing excessive pavement stresses. Further, a steel basket is subject to rusting and seizing an interrelated dowel. Further, if a steel basket is cut to size the exposed steel would be immediately subject to rust. Still further, the final installation step after placing steel baskets is to use abrasive saws or bolt cutters to separate the basket into two halves running across the roadway by cutting several ties so that the basket will not tie the concrete sections at the joint this cutting of a steel basket that has spring tension as a result of bending during shipment and/or improperly set can create a dangerous situation if the cutting of the steel causes the basket to spring open.

The basalt baskets of the instant invention, are fully scalable and normally of a comparable size to traditional steel baskets about 24″×144″ in dimension and weight less than 17.0 lbs. The basalt baskets can be stacked without crushing or deformation and an individual can carry three basalt baskets which equals the weight of a single steel basket. In addition, while the traditional 1½″×24″ steel dowel weighs about 13 lbs each, a similar fiber reinforced polymer (FRP) basalt, fiberglass or carbon fiber dowel weighs less than 4 lbs. Basalt does not rust and the use of a basalt formed basket and dowel allows size cutting without the possibility of rust, weeping, or arcing due to steel loading. Further, the use of a basalt (BFRP), glass (GFRP) or carbon fiber (CFRP) dowel can be made smooth wherein greasing is not necessary. Alternatively the non-metal dowel can be greased, pre-waxed during production, post-waxed, or coated with a bond breaking material of most any combination. Still further, the dowel and basket can include the use of bio fibers such as hemp. Additionally the use of bio based polymer resin systems based on the byproduct of alternative fuels such as ethanol can be used. While the use of the byproduct will cause approximately a 30% reduction in strength, the byproduct can be encapsulated within a strength material, such as basalt, wherein the reduction of strength will not affect the structure and will retain the properties of the basalt for bond breaking.

When two slabs are not connected, there can be no load transfer between an approach slab and a leave slap. The result is that either the approach slap or the leave slab will settle causing the roadway to become uneven. When proper doweling is placed between two slabs, the load transfer is between 70 and 90 percent. When dowels are not properly aligned, however, or if a conventional steel basket is deformed due to loading, the result is misalignment which may not show up for years after installation.

As shown in FIG. 1, a 12 inch section of 1½″ diameter dowel 10 constructed from basalt or FRP weights about 1.5 lbs and provides a surface area of 60.08 square inches. The 12 inch section of 1¼″ diameter dowel 12 constructed from basalt or FRP weights about 1.08 lbs and provides a surface area of 49.58 square inches. In the preferred embodiment, a 12 inch section of 3 lobe polygon shaped dowel 14 is constructed from basalt and weighs about 1.32 lbs to provide a surface area of 56.54 square inches, with a density of 0.07 lbs per cubic inch and a volume of 18.04 cubic inches. The average bearing stress for the 3 lobe dowel with a 6 inch embedment and 8 inch CL is less than 3400 psi. The 3 lobe polygon dowel has an oversized bearing shoulder radius of a 2.5 inch dowel.

FIG. 2 illustrates 18 inch section of a 1½″, 1¼″ and a polygon shaped dowel. The 1½″ diameter dowel 10 constructed from basalt or FRP weights about 2.32 lbs and provides a surface area of 88.36 square inches. The 1¼″ diameter dowel 12 constructed from basalt or FRP weights about 1.61 lbs and provides a surface area of 73.14 square inches. The polygon shaped dowel 168 constructed from basalt or FRP weights about 2.22 lbs and provides a surface area of 88.20 square inches. Besides the weight savings, the use of basalt reduces bearing stress concentration, reduces the need for dowel lubrication, and eliminates corrosion concerns. The 3 lobe polygon design offers a high LTE and low bearing stress with enhance load transfer distribution between dowels, as compared to steel. Dowel 168, as depicted here, has a first surface 170, a second surface 172 and a third surface 174. Surface 170 and 172 form corner 180, surface 170 and 174 form corner 182, surface 172 and 174 form corner 184.

FIGS. 3-11 depict a first embodiment of the invention wherein the basalt basket 100 is manufactured from a plurality of basalt strands 102 saturated with a thermosetting polymer which hardens when dried. The thermosetting polymer is selected from the group consisting of urethane, polyester, vinyl ester, epoxy, phenolic, polyimide, polyamide, polypropylene, PEEK, methacrylate or a combination thereof. The basket 100 is formed by wrapping the basalt strands around pins 110 which are secured to a forming base 112. The pins 110 are removably positioned within the forming-base apertures 116. The wrapping of the strands follows a predetermined pattern to format which, when dried, forms the basket 100. Each basket 100 includes alignment apertures 114 that are strategically positioned to track the forming-base apertures 116 of the forming base 112, wherein pairs of alignment apertures 114 are used for holding the dowels 120. The basket 100 also includes coiled feet 104, on which the basket 100 can be positioned, as seen in FIGS. 4 and 5. The coiled feet 104 allow the dowels 120 to be positioned horizontally at a predetermined vertical distance. At the top of the basket 100 the strands 102 come to a series of peaks 106, which helps the basket 100 form into one solid piece when hardened. The peaks 106 and feet 104 are in substantially the same vertical plane, just as the alignment holders are in substantially the same horizontal plane. As depicted in FIG. 8, the basket 100 is aligned between an approach slab 200 and leave slab 210. A dowel 120 is positioning within a pair of alignment apertures 114. The dowel 120 can be a 1½″, 1¼″ and a polygon shaped 12″ dowel and in the preferred embodiment may be 12 or 18 inches in length. The dowel 120 is constructed from basalt or FRP and weights and may be lubricated similar to a steel dowel to inhibit securement to the concrete. Once the basket 100 and dowel 120 are positioned, the concrete embeds the basket 100 and dowel 120 into the slab. As depicted in FIG. 13, the basket 100 can be at the connector tip 122 without fear of rusting found with steel baskets due to wicking.

FIGS. 9 through 11 depict how a basket 100 is formed from a section of the first embodiment of a forming base 112. As shown, there are two side members 130,132 which meet at an apex 134 to form a substantially triangular shape. The side members 130,132 can be straight, or have a bend as shown in FIG. 9. Each side member 130,132 is connected to a bottom member 136,138 which provides stability and supports the forming base 112. The forming base also has top apertures 126 along apex 134, and bottom apertures 128 along the bottom members 136,138. A basket 110 is formed by wrapping the basalt around the pins 110 in a forming base 112 in accordance with a predetermined pattern. As the basalt strands 102 are allowed to dry and solidify, the pins 110 can be removed from the forming base 112, wherein the basket 100 can be lifted from the forming base 112.

The reinforcing members produced using continuous basalt fibers (CBF) in an appropriate adhesive matrix be it a thermo plastic or a thermo set epoxy, vinyl ester or urethane. The CBF reinforcing members are formed from multiple roving (bundles) to produce the required strength for the load predictions in a similar manner to steel calculations. The micron size of the basalt fiber and the size of the CBF roving may be altered as necessary. To prevent slippage of the reinforcement within the concrete the roving's of the basket are spaced sufficiently to allow the concrete to flow between the legs and crossed and interlaces to mitigate potential for sheer at crossovers. The manufacturing process of the reinforcement is continuous without cold secondary bonds of the continuous basalt fiber with the adhesive matrix.

In light of the above and according to one aspect of the invention, the basalt basket 100 matrix and dowel 120 are used to improved concrete slabs. The extremely low stretch and cyclical tenacity of continuous basalt fiber is exploited to produce a reinforcing member and the dowels 120 are positioned to specifically provide load transfer between adjoining slabs. The reinforcing members produced using continuous basalt fibers (CBF) in an appropriate adhesive matrix be it a thermo plastic or a thermo set epoxy, vinyl ester or urethane add structural rigidity to the concrete, making the concrete capable of supporting heavy loads such as trucks wherein 70 to 98% of the load is transferred between the approach and leave slab. The CBF reinforcing members are formed from multiple roving (bundles) to produce the required strength for the load predictions in a similar manner to steel calculations. To prevent slippage of the reinforcement within the concrete the basket rovings are spaced sufficiently to allow the concrete to flow between the interlaces.

The basalt reinforcing material is constructed from continuous basalt fiber strands combined with non-corrosive thermo set or thermo plastic polymer formed into a matrix shape. Basalt fiber reinforcement does not exhibit memory and tends to return to an original cured condition and shape. Continuous basalt fiber is manufactured from basalt filaments made by melting crushed volcanic rock of a specific mineral mixture known as a breed and drawing the molten material into fibers. The fibers cool to form hexagonal chains resulting in a resilient structure having a substantially higher tensile strength than steel of the same diameter at one fifth the weight and virtually corrosion free.

Continuous basalt fiber is manufactured from basalt filaments made by melting crushed volcanic rock of a specific mineral mixture known as a breed and drawing the molten material into fibers. The fibers cool to form hexagonal chains resulting in a resilient structure having a substantially higher tensile strength than steel of the same diameter at one fifth the weight and virtually corrosion free.

Referring to FIGS. 12-17, set forth an alternative embodiment wherein a basalt basket 150 is constructed and arranged to secure 3 lobe dowels in alternate configurations wherein a dowels 152, 156, 160, 164 are placed inverted, and dowels 154, 158, and 162 are positioned conventional. For instance, dowel 168, as depicted in FIG. 2, has a first surface 170, a second surface 172 and a third surface 174. Surface 170 and 172 form corner 180, surface 170 and 174 form corner 182, surface 172 and 174 form corner 184. Depicted in FIGS. 12-15 illustrate corner 184 in a raised position and then a lower position. Dowels 152-164 form a mirror image of dowel 150.

An alternate embodiment forming base 200 is shown in FIGS. 16 and 17. The central portion of the forming base 200, is substantially trapezoidal in shape, with two angled sides 202,204 meeting a top side 206 and a bottom side 208. Additionally, there are two attached base sides 210, 212, attached through hinges 216. The hinges 216 allow the outer facing surface the base sides 210, 212 to be parallel to the outer facing surface of the angled sides 202, 204 in an initial position shown in FIG. 16 and used when wrapping strands 102 around the forming base 200, yet also change to a horizontal position, as shown in FIG. 17, when the basalt strands 212 are hardening.

The sides 202, 204 of the forming base 200 have side apertures 230 allowing a dowel pin 222 to pass through. The base sides 210, 212 have base apertures 232 for positioning base pins 220. When the dowel pins 222 and base pins 220 are in their respective apertures, and the base sides are in their initial parallel position, stands 102 can be wrapped in a predetermined pattern, weaving around the base pins 220, the dowel pins 222, and around the through top peaks 214, located on the top side 206. The top peaks 214 have a slot 234 which allows the strands 102 to come to a top point when hardened, creating a handle to lift the newly formed basket 150. By moving the base sides 210, 212 to the horizontal position prior to the strands 102 hardening, the strands 102 will bend at the hinges 216 to form the feet 104 of the basket 150.

When the strands 102 harden, the dowel pins 222 and base pins 220 can then be removed, and the basket 150 can be lifted off of the forming base 200. The alternate embodiment of the forming base 200, creates the alternate embodiment basket 150, but this basket 150 continues to function as the original embodiment basket 100 by holding dowels 120 or 150-164 in a horizontal position within the concrete slaps.

All patents and publications mentioned in this specification are indicative of the levels of those skilled in the art to which the invention pertains. Detailed embodiments of the instant invention are disclosed herein, however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific functional and structural details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representation basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.

It is to be understood that while a certain form of the invention is illustrated, it is not to be limited to the specific form or arrangement herein described and shown. It will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention and the invention is not to be considered limited to what is shown and described in the specification and any drawings/figures included herein.

One skilled in the art will readily appreciate that the present invention is well adapted to carry out the objectives and obtain the ends and advantages mentioned, as well as those inherent therein. The embodiments, methods, procedures and techniques described herein are presently representative of the preferred embodiments, are intended to be exemplary and are not intended as limitations on the scope. Changes therein and other uses will occur to those skilled in the art which are encompassed within the spirit of the invention and are defined by the scope of the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Indeed, various modifications of the described modes for carrying out the invention which are obvious to those skilled in the art are intended to be within the scope of the following claims.

Claims

1. A method of manufacturing a dimensionally scalable basalt basket constructed and arranged to align a plurality of dowels between an approach slab and a leaving slab for load transfer therebetween adjoining concrete slabs comprising the steps of: coating a plurality of basalt fiber strands with a thermoplastic polymer;wrapping said coated basalt fiber strands around a base have pins secured thereto, said wrapping following an scalable pattern to form a basket capable of holding basalt dowels;allowing said basalt strands to cure upon drying;removing said pins from said base to release a cured basket from said base;aligning said basket between an approach slab form and a leave slab form;positioning dowels within each said dowel holder formed in said basket;embedding said basket and dowels by filling said approach slab form and said leave slab form with concrete.

2. The method of manufacturing according to claim 1 wherein each said dowel is constructed from basalt.

3. The method of manufacturing according to claim 1 wherein each said dowel is constructed from the group consisting of: glass fiber reinforced polymer (FRP), basalt, hemp, carbon fiber or combinations thereof.

4. The method of manufacturing according to claim 1 wherein each said dowel has a polygon cross sectional shape.

5. The method of manufacturing according to claim 4 wherein adjoining polygon shaped dowels are inverted.

6. The method of manufacturing according to claim 1 wherein said thermoplastic polymer is selected from the group consisting of: urethane, acrylic, acetyl, polyester, vinyl ester, epoxy, phenolic, polyimide, polyamide, polypropylene, PEEK, methacrylate or a combination thereof.