Monolithic pour joint
There is provided a monolithic pour joint interposed between adjacent concrete slabs disposed on a substrate. The pour joint comprises a plurality of elongate forms interconnected with splices. Each one of the forms has a substantially planar, vertical panel with upper and lower edges and opposing ends respectively defining a form width and a form length. The forms are arranged such that the form lengths are generally aligned end to end. The lower edge of the vertical panel has a base flange extending generally laterally therefrom. A plurality of stakes are disposed in transverse relation to the form width and are secured to a side of the vertical panel at spaced intervals to fixedly maintain the forms in relation to the substrate. The pour joint may include a plurality of dowel holes extending through the vertical panel such that a dowel placement system may be installed in the pour joint.
(Not Applicable)
STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT(Not Applicable)
BACKGROUND OF THE INVENTIONThe present invention relates generally to concrete forming equipment and, more particularly, to a uniquely configured monolithic pour joint specifically adapted to prevent shear cracking of adjacently disposed concrete slabs. The pour joints are configured to facilitate the placement of dowel rods within adjacent concrete slabs.
During construction of concrete pavement such as for sidewalks, driveways, roads and flooring in buildings, cracks may occur due to uncontrolled shrinkage or contraction of the concrete. Such cracks are the result of a slight decrease in the overall volume of the concrete as water is lost from the concrete mixture during curing. Typical contraction rates for concrete are about one-sixteenth of an inch for every ten feet of length. Thus, large cracks may develop in concrete where the overall length of the pavement is fairly large. In addition, the cracks may continue to develop months after the concrete is poured due to induced stresses in the concrete.
One of the most effective ways of controlling the location and direction of the cracks is to include longitudinal control joints or contraction joints in the concrete. Contraction joints are typically comprised of forms having substantially vertical panels that are positioned above the ground or subgrade and held in place utilizing stakes that are driven into the subgrade at spaced intervals. The forms act to subdivide or partition the concrete into multiple sections or slabs that allow the concrete to crack in straight lines along the contraction joint. By including contraction joints, the slabs may move freely away from the contraction joint during concrete shrinkage and thus prevent random cracking elsewhere.
In one system of concrete construction, forms are installed above the subgrade to create a checkerboard pattern of slabs. A first batch of wet concrete mixture is poured into alternating slabs of the checkerboard pattern. After curing, forms may be removed and the remaining slabs in the checkerboard pattern are poured from a second batch of concrete. Although effective in providing longitudinal contraction joints to prevent random cracking, the checkerboard system of concrete pavement construction is both labor intensive and time consuming due to the need to remove the forms and due to the waiting period between the curing of the first batch and the pouring of the second batch of concrete.
In another system of concrete construction known as monolithic pour technique, the pour joints are installed above the subgrade in the checkerboard pattern. However, all of the slabs of the checkerboard pattern are poured in a single pour thereby reducing pour time as well as increasing labor productivity. An upper edge of the forms then serves as a screed rail for striking off or screeding the surface of the concrete so that the desired finish or texture may be applied to the surface before the concrete cures. The pour joints, comprised of vertically disposed forms, remain embedded in the concrete and provide a parting plane from which the slabs may move freely away during curing. The pour joints additionally allowing for horizontal displacement of the slabs caused by thermal expansion and contraction of the slabs during normal everyday use.
Unfortunately, vertical displacement of adjacent slabs may also occur at a joint due to settling or swelling of the substrate below the slab or as a result of vertical loads created by vehicular traffic passing over the slabs. The vehicular traffic as well as the settling or swelling of the subgrade may create a height differential between adjacent slabs. Such height differential may result in an unwanted step or fault in a concrete sidewalk or roadway or in flooring of a building creating a pedestrian or vehicular hazard. Furthermore, such a step may allow for the imposition of increased stresses on the corner of the concrete slab at the joint resulting in degradation and spalling of the slab. In order to limit relative vertical displacement of adjacent slabs such that steps are prevented from forming at the joints, a form of vertical load transfer between the slabs is necessary.
One system for limiting relative vertical displacement and for transferring loads between slabs is provided by key joints. In key joint systems, the form is configured to impart a tongue and groove shape to respective ones of adjacent slabs. Typically preformed of steel, such a key joint imparts the tongue and groove shape to adjacent slabs in order to allow for contraction and expansion of the adjacent slabs while limiting the relative vertical displacement thereof due to vertical load transfer between the tongue and groove. The tongue of one slab is configured to mechanically interact with the mating groove of an adjacent slab in order to provide reactive shear forces across the joint when a vertical load is place on one of the slabs. In this manner, the top surfaces of the adjacent slabs are maintained at the same level despite swelling or settling of the subgrade underneath either one of the slabs. Additionally, edge stresses of each of the slabs are minimized such that chipping and spalling of the slab corners may be reduced.
Although the key joint presents several advantages regarding its effectiveness in transferring loads between adjacent slabs, key joints also possess certain deficiencies that detract from their overall utility. Perhaps the most significant of these deficiencies is that the tongue of the key joint may shear off under certain loading conditions. Furthermore, the face of the key joint may spall or crack above or below the groove under load. The location of the shearing or spalling is dependent on whether the load is applied on the tongue side of the joint or the groove side of the joint. If the vertical load is applied on the tongue side, the failure will occur at the bottom portion of the groove. Conversely, if the vertical load is applied on the groove side of the joint, the failure will occur near the upper surface of the slab upon which the load is applied.
Shear failure of the tongue and groove may also occur due to opening of the key joint as a result of shrinkage of the concrete slab. As the key joint opens up over time, the groove side may become unsupported as the tongue moves away. Vertical loading of this unsupported concrete causes cracking and spalling parallel to the joint. Such cracking and spalling may occur rapidly if hard-wheeled traffic such as forklifts are moving across the joint. Another deficiency associated with key joint systems is related to the size, configuration and vertical placement of the tongue and groove within the key joint. If excessively large key joints are formed in adjacent slabs or if the tongue and groove are biased toward an upper surface of the slabs instead of being placed at a more preferable midheight location, spalls may occur at the key joint. Such spalls occurring from this type of deficiency typically run the entire length of the longitudinal key joint and are difficult to repair.
Furthermore, key joints suffer from an additional deficiency in that slip dowel systems may not be compatible for use with preformed metallic key joint forms due to interference thereof with a flanged base member of the slip dowel system. Slip dowels are typically configured as smooth steel dowel rods that are placed within edge portions of adjacent concrete slabs in such a manner that the concrete slabs may slide freely along the slip dowels thereby permitting expansion and contraction of the slabs while simultaneously maintaining the slabs in a common plane and thus prevent unevenness or steps from forming at the joint. Because slip dowels are typically located near the midheight of a contraction joint, the tongue and groove of the metal form may interfere with the installation of the flanged base member of the slip dowel system.
As can be seen, there exists a need in the art for a joint system capable of minimizing relative vertical displacement of adjacent concrete slabs caused by settling or swelling of the subgrade or by vertical loads that may be imposed by vehicular traffic. Furthermore, there exists a need for a joint system capable of resisting shear failures at respective faces of adjacent concrete slabs. Finally, there exists a need for a joint system that is compatible with slip dowel systems such that slip dowels may be placed within adjacent concrete slabs to aid in maintaining the slabs in a common plane.
BRIEF SUMMARY OF THE INVENTIONThe present invention specifically addresses and alleviates the above-referenced deficiencies associated with contraction joints of the prior art. More particularly, the present invention is an improved, monolithic pour joint that is specifically adapted to prevent shear cracking of adjacently disposed concrete slabs while accommodating slip dowel systems for aiding in the placement of slips dowels within edge portions of adjacent concrete slabs.
The pour joint is comprised of at least one elongate form or a plurality of forms arranged in end-to-end alignment with a splice interconnecting the forms and a plurality of elongate stakes secured to a side of the forms to fixedly maintain or support the forms above the substrate. Each of the elongate forms includes a substantially planar, vertical panel having an upper edge and a lower edge to define a form width and opposing ends that define a form length. The lower edge of the form has a base flange that extends laterally from the vertical panel such that the form defines an L-shaped configuration.
The forms, splices and stakes may be fabricated of metal such as galvanized sheet metal. A plurality of the stakes are secured to the vertical panel and are disposed in transverse relation to the form width at spaced intervals along the form length. Each one of the stakes has a stake body with an upper end and a lower end. The upper end of the stake body is adapted to abut against the vertical panel. The lower end of the stake body may be provided with a point such that the stake may be driven into a substrate of soil.
The splices are configured to interconnect adjacent ones of the forms at the lower edges and may be secured to the vertical panel with mechanical fasteners such as self-tapping screws. The splices may be configured in a shape that is complementary to the form such as in an L-shaped configuration matching the L-shaped configuration of the form. The stakes for supporting the form may also be secured to the vertical panel with self-tapping screws. Additionally, the stakes may be secured to the lower edge of the vertical panel with at least one stake clip that may be integrally formed with and extensible from the stake body such that the form may be rigidly held at a preset height above the substrate.
The pour joint of the present invention is configured to be compatible with dowel placement systems due to the inclusion of dowel holes in the forms and due to the generally planar configuration of the vertical panel. Such dowel placement systems may be provided at spaced intervals in the pour joints as a means of preventing buckling or relative angular or vertical displacement of the slabs. A sleeve of the dowel placement system may be mounted on the form by insertion through the dowel hole. A sleeve flange of the sleeve is abutted against and secured to the planar vertical panel with fasteners. A sheath may be inserted into the sleeve with steel or iron dowel rods being advanced into the sheath prior to the pouring of concrete slabs such that the slabs may slide freely during expansion and contraction of the slabs to maintain the slabs in a common plane and thus prevent unevenness or steps from forming at the pour joint.
A layer of resilient joint filler may be included along a side of the vertical panel. The joint filler may be configured to alternately compress and expand during relative lateral movements of the concrete slabs such as may occur during thermal expansion and contraction. The joint filler prevents the entrapment of stones, debris or other material between the slabs that may otherwise interfere with thermal expansion of the slabs. The joint filler may be fabricated from foam material such as fiber board, closed-cell foam rubber or low density, closed-cell polyethylene foam. An edge cap may also be mounted upon and extend along the upper edge of the form in order to provide protection against water infiltration and particle entrapment within the pour joint. The edge cap may be formed as an extrusion of relatively flexible, elastomeric material such as a plastic material.
BRIEF DESCRIPTION OF THE DRAWINGSThese as well as other features of the present invention will become more apparent upon reference to the drawings wherein:
Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention and not for purposes of limiting the same,
Each of the forms 16 includes a substantially planar, vertical panel 18 having an upper edge 20 and a lower edge 22 to define a form 16 width. Each of the forms 16 also has opposing ends 24 that define a form 16 length. In one embodiment of the form 16 shown in
The forms 16, splices 60 and stakes 48 may be fabricated of metal such as sheet metal. The sheet metal may be a steel sheet material. A galvanized coating on the steel sheet may be included in order to provide maximum protection of the metal from exposure to concrete which may other wise result in corrosion. Other coatings for the sheet metal are contemplated and may include powder coating and epoxy coating. In addition, the forms 16, splices 60 and stakes 48 may be fabricated of fiber glass, carbon fiber, Kevlar, or a polymeric material such as plastic or any combination thereof. However, it is contemplated that the forms 16, splices 60 and stakes 48 may be fabricated from any number of alternative materials.
A plurality of the stakes 48 may be secured to the vertical panel 18 in order to support the forms 16 at a preset height above the substrate 14. The stakes 48 are disposed in transverse relation to the form 16 width and are secured to a side of the vertical panel 18 at spaced intervals along the form 16 length. The spacing of the stakes 48 along the form 16 length may be adjusted based on a number of factors including the condition of the underlying soil and the thickness of the slabs 12. Each one of the stakes 48 has a stake body 50 with an upper end 52 and a lower end 54. The upper end 52 of the stake body 50 may be adapted to abut against the vertical panel 18 as shown in
It is contemplated that the pour joint 10 may be comprised of only a single one of the forms 16 with at least one stake 48 or a pair of the stakes 48 being secured to the vertical panel 18 adjacent to the ends 24 of the form 16 in order to support the form 16 above the substrate 14. However, the forms 16 may be arranged in a manner similar to that shown in
The splices 60 may be secured to the vertical panel 18 with mechanical fasteners 62 extending through the splice 60 and into the vertical panel 18 of the form 16 and/or into the base flange 26 of the form 16. The mechanical fasteners 62 may be self-tapping screws or sheet metal screws as is shown in
The stakes 48 for supporting the form 16 may be attached to the vertical panel 18 with mechanical fasteners 62, as can be seen in
Referring now to
The sleeve 38 is mounted on the form 16 by insertion through the dowel hole 64. The sleeve 38 may include a sleeve flange 40 that is abutted against and secured to the planar vertical panel 18 of the form 16. As is shown in
Steel or iron reinforcing bars or dowel rods 46 may then be advanced into the sheath 42 prior to the pouring of concrete slabs 12 such that the slabs 12 may slide freely during expansion and contraction of the slabs 12. The dowel placement systems 36 maintain the slabs 12 in a common plane and thus prevent unevenness or steps from forming at the pour joint 10. As is shown in
The dowel holes 64 may be sized and configured to be complementary to the sleeve 38 of the dowel placement system 36 and may be disposed at spaced intervals along the form 16 length depending on the loading conditions that may be imposed upon the slabs 12 and also depending upon the stability of the underlying substrate 14. The longitudinal spacing of the dowel holes 64 may be such that dowel holes 64 are provided at regularly spaced intervals such as at six-inch spacings along the form 16 length. The dowel placement systems 36 may be installed along the pour joint 10 at wider spacings wherein some of the dowel holes 64 between the dowel placement systems 36 are unused.
As is shown in
Referring now to
Referring now to
In addition, the joint filler 66 may be configured to prevent the entrapment of stones, debris or other material between the slabs 12 that may otherwise interfere with thermal expansion of the slabs 12. The joint filler 66 may also provide a weather tight seal preventing excess moisture from entering the space between adjacent ones of the slabs 12 which may otherwise lead to freeze-thaw cracking of the concrete slabs 12. Toward this end, the joint filler 66 may be fabricated from foam material such as fiber board, closed-cell foam rubber or low density, closed-cell polyethylene foam. Such foam may be pre-formed at a predetermined thickness that is sized to be complementary to a gap between the slabs 12. The joint filler 66 may include an adhesive layer on one side thereof for facilitating installation to the vertical panel 18.
Referring still to
Alternatively, for pour joint 10 configurations wherein the joint filler 66 is omitted, the edge cap 68 may be configured to be mounted directly upon the form 16 itself with the cap legs 70 being spaced apart at a width complementary to a thickness of the upper edge 20 of the vertical panel 18. As mentioned above, such upper edge 20 of the vertical panel 18 may include the folded-over portion 28 in which case the cap legs 70 may be spaced apart at a complementary width. The edge cap 68 may be fabricated as an extrusion from a relatively flexible, elastomeric material such as a plastic material. Such plastic material may be polystyrene, vinyl or other material. However, other materials may be used to fabricate the edge cap 68. The edge cap 68 may be bonded to the pour joint 10 with adhesive such as a semi-rigid epoxy adhesive in order to reduce the tendency for cracking of the slabs 12.
Referring now to
The earlier-described dowel placement system 36 is shown in
Referring now to
The stake clip 56 may also be configured in a generally U-shaped cross-section extending from the stake body 50 and configured to receive the form 16. As shown in
Although not shown, the stake clip 56 may be configured as a separate component that is configured to interlock the stake body 50 to the form 16. In such a configuration, the stake clip 56 may be configured to straddle the stake body 50 and engage the lower edge 22 of the vertical panel 18 for restraining the form 16 against the stake 48 during lateral displacement caused by pouring of wet concrete on a side of the pour joint 10. The ribs 58 formed in the upwardly extending portions allow the stake clip 56 to grippingly engage the lower edge 22 of the form 16.
The operation of the pour joint 10 will now be described with reference to
The forms 16 are then installed on the stakes 48 with splices 60 interconnected to opposing ends 24 of the forms 16. If separate ones of the stake clips 56 are included, such stake clips 56 are then mounted on the stake body 50 such that the stake clips 56 engage the lower edge 22 of the vertical panel 18. If included, a layer of joint filler 66 may be mounted against a side of the form 16. Edge caps 68 may then be installed along the forms 16. Dowel placement systems 36 may be installed in the forms 16 at a desired spacing. If the dowel holes 64 are configured as knockouts, such knockouts are first bent outwardly or removed such that the sleeves 38 of the respective ones of the dowel placement system 36 may be installed in the dowel holes 64. Sheaths 42 are the attached to the respective ones of the sleeves 38 and the dowels rods 46 are then inserted into the sheaths 42. Wet concrete is then poured over the substrate 14. Prior to curing, the concrete is leveled. A pair of the pour joints 10 may be utilized to screed the top surface of the slabs 12 after which a finish may be applied to the freshly poured concrete.
Additional modifications and improvements of the present invention may also be apparent to those of ordinary skill in the art. Thus, the particular combination of parts described and illustrated herein is intended to represent only certain embodiments of the present invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.
Claims
1. A monolithic pour joint interposed between adjacent concrete slabs disposed on a substrate, the pour joint comprising:
- an elongate form having a planar, vertical panel with upper and lower edges and opposing ends respectively defining a form width and a form length, the lower edge having a base flange extending generally laterally therefrom; and
- a plurality of elongate stakes disposed in transverse relation to the form width and secured to a side of the vertical panel opposite that from which the base flange extends, the stakes being disposed at spaced intervals along the form length;
- wherein the stakes are configured to fixedly maintain the form in relation to the substrate.
2. The pour joint of claim 1 further comprising a plurality of dowel holes extending through the vertical panel.
3. The pour joint of claim 1 further comprising:
- a plurality of splices configured to be complementary to the form; and
- a plurality of the forms being arranged such that the form lengths are generally aligned end to end;
- wherein each one of the splices is secured to and interconnects adjacent ones of the forms at the lower edges thereof.
4. The pour joint of claim 1 wherein the splices are secured to the vertical panel with mechanical fasteners.
5. The pour joint of claim 1 wherein the stakes are secured to the vertical panel with mechanical fasteners.
6. The pour joint of claim 1 wherein the upper edge includes a folded-over portion extending downwardly therefrom.
7. The pour joint of claim 1 further comprising a layer of resilient joint filler disposed along a side of the vertical panel.
8. The pour joint of claim 7 wherein the joint filler is fabricated from foam material.
9. The pour joint of claim 1 further comprising an elongate edge cap extending along the upper edge.
10. The pour joint of claim 9 wherein the edge cap is fabricated from plastic material.
11. A monolithic pour joint interposed between adjacent concrete slabs, the pour joint comprising:
- an elongate form having a planar, vertical panel with upper and lower edges and opposing ends respectively defining a form width and a form length, the upper edge having an upper flange of inverted generally U-shaped cross-section including a horizontal section extending laterally from the upper edge and terminating in a downwardly extending vertical section that is spaced apart from the vertical panel; and
- a plurality of elongate stakes disposed in transverse relation to the form width and secured to a side of the vertical panel opposite that from which the base flange extends, the stakes being disposed at spaced intervals along the form length, each one of the stakes having a stake body with upper and lower ends;
- wherein the upper flange is configured to receive the upper end of the stake body such that the stakes may support the form in relation to the substrate.
12. The pour joint of claim 11 wherein the upper flange is configured to be resiliently flexible and is spaced away from the vertical panel such that the upper flange may grippingly engage the upper end of the stake body.
13. The pour joint of claim 11 wherein each of the stakes includes at least one stake clip of generally U-shaped cross-section extending from the stake body, the stake clip being configured to receive the lower edge of the form.
14. The pour joint of claim 13 wherein the stake clip is configured to be resiliently flexible such that the stake clip may grippingly engage the lower edge.
15. The pour joint of claim 11 further comprising a plurality of dowel holes extending through the vertical panel.
16. The pour joint of claim 11 further comprising:
- a plurality of splices configured to be complementary to the form; and
- a plurality of the forms being arranged such that the form lengths are generally aligned end to end;
- wherein each one of the splices is secured to and interconnects adjacent ones of the forms at the lower edges thereof.
17. The pour joint of claim 16 wherein the splices are secured to the vertical panel with mechanical fasteners.
18. The pour joint of claim 11 further comprising a layer of resilient joint filler disposed along a side of the vertical panel.
19. The pour joint of claim 18 wherein the joint filler is fabricated from foam material.
20. The pour joint of claim 11 further comprising an elongate edge cap extending along the upper edge.
21. The pour joint of claim 20 wherein the edge cap is fabricated from plastic material.
22. A monolithic pour joint interposed between adjacent concrete slabs disposed on a substrate, the pour joint comprising:
- an elongate form having a planar, vertical panel with upper and lower edges and opposing ends respectively defining a form width and a form length, the vertical panel having a plurality of dowel holes extending therethrough;
- a plurality of elongate stakes disposed in transverse relation to the form width and secured to a side of the vertical panel at spaced intervals along the form length and being configured to fixedly maintain the form in relation to the substrate;
- at least one sleeve mounted through one of the dowel holes and extending laterally outwardly from the vertical panel and into one of the concrete slabs;
- an elongate, tubular dowel-receiving sheath sized and configured to be insertable into and joinable to the sleeve; and
- an elongate dowel rod extending laterally across the pour joint and being freely slidable within the sheath embedded within one of the concrete slabs and fixedly captured within the adjacent one of the concrete slabs.
23. The monolithic pour joint of claim 22 wherein the lower edge has a base flange extending generally laterally therefrom.
24. The monolithic pour joint of claim 22 wherein:
- the sleeve includes a sleeve flange disposed on an end thereof and having at least one dimple disposed on an exterior of the sleeve;
- the sleeve flange extending laterally outwardly from the sleeve and being configured for mounting the sleeve to the vertical panel;
- the dimple being disposed in spaced relation to the sleeve flange and being positioned such that the vertical panel is capturable between the sleeve flange and the dimple.
25. The monolithic pour joint of claim 24 wherein the sleeve flange includes fastener holes spaced therearound, the fastener holes being sized and configured to permit the passage of a fastener therethrough for attachment of the sleeve to the vertical panel.
26. The monolithic pour joint of claim 22 wherein the sleeve includes a plurality of dimples disposed in spaced relation around the exterior of the sleeve, each one of the dimples having a wedge-shaped configuration.
Type: Application
Filed: Aug 13, 2003
Publication Date: Feb 17, 2005
Inventors: Lee Shaw (Newport Beach, CA), Ronald Shaw (Corona Del Mar, CA)
Application Number: 10/638,809