The present invention relates to concrete fabrication and repair, and more particularly to a modular system and method for concrete crack repair.
Although mechanically strong in compression, concrete is relatively weak in tensile and bending loads and may be subject to cracking and breakage under such conditions. Concrete installations typically include strengthening material, such as rebar, to increase tensile strength. Some concrete installations use a post-tensioning technique to pre-load the concrete and place it under a resting compressive load. This counteracts tensile and bending loads to mitigate mechanical failures. Over time, however, environmental factors such as frost heaving, ground movement, erosion, water infiltration, and the like may still cause cracking and mechanical failure of installed concrete.
Reinforcement and post-tensioning are typically performed during original installation of concrete. Reinforcement and optionally, post-tensioning, can also be advantageously applied to concrete repairs. Typically, a metal rod is recessed into the concrete such that the rod spans across the crack to be repaired. Where post-tensioning is desired, tension may be applied across the rod to close the crack. New concrete may be applied over the rod to complete the repair. Current repair systems, however, are limited to use in repairing easily accessible cracks with relatively simple geometries (e.g., on sidewalks, driveways, roads, etc.).
The present invention provides, in one aspect, a system for repairing a crack in a concrete installation. The system includes a stitch having a center portion configured to span across the crack and an anchor plate coupled to the stitch. The anchor plate includes an anchor bore configured to receive a concrete anchor, a first bore extending parallel to the anchor bore, a second bore extending transverse to the anchor bore, and a groove extending transverse to the first bore and the second bore. The first bore intersects the groove, and the second bore intersects the anchor bore.
The present invention provides, in another aspect, an anchor plate for coupling to a stitch that extends across a crack in a concrete installation. The anchor plate includes a top side, a bottom side opposite the top side, a first lateral side extending between the top side and the bottom side, a second lateral side extending between the top side and the bottom side, a third lateral side extending between the top side and the bottom side opposite the first lateral side, a fourth lateral side extending between the top side and the bottom side opposite the second lateral side, an anchor bore configured to receive a concrete anchor, the anchor bore extending through the top side and the bottom side, a first bore extending through the top side and the bottom side, a second bore extending through the second lateral side, and a groove formed in the bottom side, the groove extending between the first lateral side and the third lateral side.
The present invention provides, in another aspect, a method of repairing a crack in a concrete installation. The method includes forming a first recess in the concrete installation on a first side of the crack, forming a second recess in the concrete installation on a second side of the crack opposite the first side, forming a channel in the concrete installation between the first and second recesses, applying an epoxy into the first recess, the second recess, and the channel, and positioning a stitch in the channel such that a center portion of the stitch spans across the crack from the first side to the second side. Positioning the stitch in the channel includes positioning a first end segment of the stitch in the first recess and positioning a second end segment of the stitch in the second recess. The first end segment and the second end segment are angled relative to the center portion.
Other features and aspects of the invention will become apparent by consideration of the following detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
With reference to
An anchor bore 54 extends through the main body 34 of the anchor plate 14 from the top side 38 to the bottom side 42. In the illustrated embodiment, the anchor bore 54 extends perpendicular or transverse to the longitudinal axis 50 and is elongated in the direction of the longitudinal axis 50 (
The anchor plate 14 further includes a plurality of attachment features to facilitate coupling the stitch 18, the tensioning assembly 26, or both to the anchor plate 14. In the illustrated embodiment, the plurality of attachment features includes a first bore 58 extending through the top side 38, a second bore 62 extending through the second lateral side 46b, and a groove 66 formed in the bottom side 42 of the main body 34. The first bore 58 extends through the main body 34 and intersects a center of the groove 66. The second bore 62 extends along the longitudinal axis 50 from the second lateral side 46b and intersects anchor bore 54. As such, in the illustrated embodiment, the first bore 58 communicates with the groove 66, and the second bore 62 communicates with the anchor bore 54.
With reference to
The anchor bore axis 54a is perpendicular or transverse to the longitudinal axis 50 (and the second bore axis 62a), and the first bore axis 58a is parallel to the anchor bore axis 54a. The first bore axis 58a, the second bore axis 62a, the longitudinal axis 50, and the anchor bore axis 54a are coplanar. The groove 66 extends along the bottom side 42, from the first lateral side 46a to the third lateral side 46c and parallel to the second and fourth lateral sides 46b, 46d of the main body 34. As such, the groove axis 66a is perpendicular or transverse to each of the first bore axis 58a, the second bore axis 62a, the anchor bore axis 54a, and the longitudinal axis 50. In other embodiments, the relative position or orientation of one or more of the attachment features may differ.
In the illustrated embodiment, the groove 66 has a semi-circular cross-section. The groove 66, the first bore 58, and the second bore 62 each have approximately the same diameter. As described in greater detail below, the diameter of each of these attachment features is sized to receive at least a portion of the stitch 18, the tensioning assembly 26, or both.
An exemplary stitch 18 for use with the system 10 is illustrated in
With continued reference to
The stitch 18 is formed from a unitary piece of rigid, high-strength material, such as steel, fiber-reinforced composite, fiberglass, or any other material suitable for use in concrete repair. In certain embodiments, the stitch 18 comprises a cold-rolled material, including cold rolled alloys sometimes referred to by the trade name Stressproof®. The cold-rolled material can comprise a material conforming to AISI 1144. AISI 1144 steel is a carbon-manganese grade steel which is cold worked to produce high tensile properties. In some embodiments, the stitch 18 has a tensile strength of at least 90,000 psi. In some embodiments, the stitch 18 has a tensile strength of at least 100,000 psi. In some embodiments, the stitch 18 has a tensile strength of 115,000 psi. In some embodiments, the stitch 18 may be treated or coated for enhanced corrosion resistance. For example, the stitch 18 may be plated with zinc in some embodiments.
The system 10 is usable in a method of repairing a crack in a concrete installation. Particularly, in some embodiments, a user first prepares a concrete installation to be repaired. Preparing the concrete installation includes drilling holes or recesses on opposite sides of a crack in a concrete installation. In some embodiments, each of the holes is spaced from the crack by a distance of at least about 6 inches. In some embodiments (e.g., when the concrete installation has a slab thickness of at least 5 inches), the holes are drilled to a depth of about 4 inches and have a diameter of about ⅝ inches. In other embodiments (e.g., when the concrete installation has a slab thickness less than 5 inches), the holes may be drilled to a shallower depth and a smaller diameter for use with smaller anchors 22.
Next, a recess or channel is cut into the concrete installation between the drilled holes (e.g., using a masonry saw, a chipping hammer, etc.). The channel may be cut to a depth of about 1½ inches along the entire length of the channel. Alternatively, if the slab thickness of the concrete installation is less than 5 inches, the channel may be cut to a shallower depth, such as about ½ of an inch. After forming the holes and the channel, in some embodiments, an epoxy, such as AE-2200-250 Anchoring Epoxy by AquaBond®, is applied into the holes and along the bottom of the channel.
After preparing the concrete installation, the user positions the system 10 on the concrete installation. In some embodiments, the stitch 18 is coupled to the anchor plates 14 (e.g., via one of the attachment features) so as to span between the anchor plates 14. The anchor plates 14 and the stitch 18 are positioned in the channel so as to be recessed below the outer surface of the concrete installation. In particular, the anchor plates 14 are positioned over the drilled holes, with the anchor bores 54 aligned with the holes. Then, an anchor 22 is inserted through the anchor bore 54 of each anchor plate 14 and secured into the hole (e.g., by tightening the anchor 22 to a specified torque). For example, in some embodiments, each anchor 22 is tightened to a torque of about 50 foot-pounds. The stitch 18 links the concrete on opposite sides of the crack to permit load transfer across the crack. In some embodiments described, the system 10 may optionally be configured to allow post-tensioning across the crack to further strengthen the repair. In other embodiments, post-tensioning may not be required.
The process can be repeated to install multiple stitches 18 along the length of the crack if necessary. In some embodiments, multiple stitches 18 may be positioned along the crack at a spacing between 8 inches and 12 inches between adjacent stitches 18.
In some embodiments, the stitches 18 may also be provided in various lengths to suit a particular concrete installation, and longer stitches 18 may be used (when space allows) to provide stronger repairs. For example, in some embodiments, a particular stitch 18 may have an overall length of about 6-inches, about 12-inches, about 18-inches, or about 24-inches. Other lengths may also be provided. In some embodiments, the system 10 may include a plurality of stitches 18 having a plurality of different overall lengths.
The attachment features of the anchor plate 14, combined with the geometry of the stitch 18, advantageously permits the system 10 to be configured in a variety of different ways to facilitate use in a wide variety of concrete installations. For example, with reference to
In some embodiments, (e.g., when the slab thickness is less than 5 inches), the system 10 may be configured for use without the anchors 22 or anchor plates 14. For example, in one configuration illustrated in
In another configuration illustrated in
In some embodiments, such as those illustrated in
Once each of the stitches 18 is positioned in its respective channel, the epoxy may be allowed to cure for a curing time period. In some embodiments, the curing time period is at least 24 hours. After the epoxy is cured, each channel is filled with concrete, non-shrinking hydraulic cement, foam (e.g., polyurethane foam), or any other suitable filling material, to encase all of the stitches 18, anchors 22, and anchor plates 14 of the system 10 and inhibit moisture and/or oxygen intrusion.
The material properties of the stitch 18, including its cold-rolled processing and high tensile strength, advantageously provides for stronger and longer lasting repairs while minimizing the diameter of the stitch 18. As such, the required size of the channel is minimized, which reduces disruption to the surface of the concrete installation. Finally, the inventors discovered that material properties of the stitch 18 may also advantageously provide longer-lasting repairs by minimizing creep. Creep is a deformation mechanism that is a function of a material's properties, temperature exposure, time, and applied structural load. Reinforcing metals in concrete installations are not typically subject to high temperatures where creep is commonly observed and accounted for. The inventors have found, however, that creep may also occur and contribute to failures within concrete installations, at least in part due to high structural loads that exist for an extended period of time. The cold-rolled processing and high tensile strength of the stitch 18 advantageously minimize the creep potential of the stitch 18.
The material properties of the stitch 18 and its geometry (including the angled end segments 82, 90 in some embodiments) may advantageously provide a strong modulus for locking and limiting future movement of a fractured wall or other concrete installation due to heaving or other environmental factors. In some embodiments, an even stronger modulus may be provided by layering stitches 18 on top of one another (either longitudinally or in a crossing pattern), and coupling the layered stitches 18 together with epoxy. Thus, concrete repairs made using the systems and methods described herein may be longer lasting and more resistant to heaving than typical concrete repairs.
Referring to
The base plate 102 includes a first bore 110 and a second bore 114, each configured to receive a threaded fastener 118 (
With reference to
Illustrated in
Referring to
The modular nature of the system 10 allows for multiple anchor plates 14 to be coupled to a single stitch 18 and positioned relative to the stitch 18 in various ways. In other embodiments, multiple stitches 18 may be coupled to a single anchor plate 14. In yet other embodiments, one or more tensioning assemblies 26 may be coupled to an anchor plate 14, with or without a stitch 18. In some embodiments, the bridge plate 30 may couple multiple stitches 18, anchor plates 14, and/or tensioning assemblies 26 together. Several exemplary configurations of the system 10 are described and illustrated herein. One of ordinary skill in the art would understand, however, that the system 10 may also be used in other configurations to suit the particular geometry and properties of a crack to be repaired.
For example,
Thus, it is evident from at least the configurations described and illustrated above with reference to
In use, the anchors 22 are secured into anchor holes drilled into a concrete installation to be repaired on opposite sides of a crack, generally in the same manner as in the method described above. The tensioning assembly 26 is positioned to extend between the anchor plates 14 and across the crack. As such, the tensioning assembly 26 defines a stitch that spans across the crack. An operator can then tighten the fasteners 118 on the tensioning assembly 26, which applies tension to the rods 106 and anchor plates 14, tending to draw the anchors 22 closer together and closing a gap between the base plates 102 of each sub-assembling 100. In some embodiments, the gap between the base plates 102 may be fully closed by rotating each of the fasteners 118 about 180 degrees. Closure of the gap between the base plates 102 may indicate to the user that proper post-tensioning has been performed. The system 10 including the tensioning assembly 26 can thus apply adjustable tension across a crack, strengthening the crack and allowing for load transfer across the crack.
The system 210 integrates the function of the tensioning assembly 26 with the anchor plate 14. In particular, the system 210 includes an anchor plate 214 with a first bore 258 that is obliquely angled relative to the anchor bore 254 so as to define a cam surface 255. The stitch 218 of the system 210 includes one end segment 282 that is obliquely angled relative to the center portion 278. In the illustrated embodiment, the cam surface 255 extends at an angle θ of about 15 degrees relative to vertical, with reference to the orientation illustrated in
In use, when the anchor 222 is tightened, the anchor plate 214 is forced downward in the direction of arrow A. The cam surface 255 in the first bore 258 bears against the end segment 282 to draw the opposite end segment 290 of the stitch 218 toward the anchor 222. This allows for tension to be applied across the crack.
With reference to
With reference to
In alternate embodiments (not shown), the stitch 418 or one of the rods 506 may be generally L-shaped, including an end segment that extends at an angle relative to the remainder of the stitch 418 or rod 506. In such embodiments, the stitch 418 or the rod 506 may be fixed to one of the anchor plates 414 and coupled to the other anchor plate 414 via one of the attachment features (458, 462, 466) of the anchor plate 414. Alternatively, the second anchor plate 414 may be omitted and the end segment configured to interface directly with the concrete installation to be repaired.
As evidenced by the various exemplary embodiments and configurations described herein, the present disclosure provides a modular system and method for concrete crack repair that may advantageously be used on concrete installations of various sizes, thicknesses, and shapes (e.g., corners, curves, and straight surfaces) to durably repair cracks of various types and severities.
Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the invention as described.
Various features of the invention are set forth in the following claims.
This application claims priority to co-pending U.S. Provisional Patent Application No. 62/787,052, filed on Dec. 31, 2018, the entire content of which is incorporated herein by reference.
Number | Date | Country | |
---|---|---|---|
62787052 | Dec 2018 | US |