US20230366203A1

US20230366203A1 - Adjustable rod holder for concrete construction

Info

Publication number: US20230366203A1
Application number: US18/196,477
Authority: US
Inventors: Thomas M. Espinosa
Original assignee: Cetres Holdings LLC
Current assignee: Cetres Holdings LLC
Priority date: 2022-05-13
Filing date: 2023-05-12
Publication date: 2023-11-16
Also published as: WO2023220334A1

Abstract

A rod holder for being embedded in concrete includes a body including a first opening for holding an end portion of a threaded rod, the first opening including an upper portion and a lower portion, the upper portion including threads for threaded connection with the threaded rod; and the body including a vertical slot in a sidewall of the lower portion of the first opening, the slot for making visible an end portion of the threaded rod to ensure minimum threaded connection of the threaded rod in the upper portion while the threaded rod is adjusted vertically.

Description

RELATED APPLICATION

This is a nonprovisional application of Provisional Application Ser. No. 63/341,713, filed May 13, 2022, which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention is generally directed to rod holders for concrete construction and particularly to holders for anchor rods and concrete anchors and screed chairs.

SUMMARY OF THE INVENTION

The present invention provides a rod holder for being embedded in concrete, comprising a body including a first opening for holding an end portion of a threaded rod, the first opening including an upper portion and a lower portion, the upper portion including threads for threaded connection with the threaded rod; and the body including a vertical slot in a sidewall of the lower portion of the first opening, the slot for making visible an end portion of the threaded rod to ensure minimum threaded connection of the threaded rod in the upper portion while the threaded rod is adjusted vertically.
The present invention also provides a rod holder for being embedded in concrete, comprising a body including a first opening with a first diameter and a second opening with a second diameter for holding an end portion of a first threaded rod with the first diameter in the first opening or a second threaded rod with the second diameter in the second opening; and the first diameter being smaller than the second diameter.
The present invention further provides a rod holder for being embedded in concrete, comprising a plastic body including leg portions to elevate the body above a formboard, and a center post with a first opening, the center post extending to the formboard; a first nut and a second nut disposed in the first opening, the first nut being above the second nut; the first opening including a bottom wall with a second opening for receiving a screw for attaching the holder to the formboard, the bottom wall being breakable from the center post with the screw when the formboard is removed; and the first nut for holding an end portion of a first threaded rod, the second nut for holding an end portion of a second threaded nut inserted into the first opening from below when the formboard is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top perspective view of a rod holder embodying the present invention.

FIG. 2 is a top view of FIG. 1 .

FIG. 3 is a side view of FIG. 2 .

FIG. 4 is a bottom perspective view of FIG. 1 .

FIG. 5 is an enlarged perspective cross-sectional view taken along line 5-5 in FIG. 2 .

FIG. 6 is top perspective view of another embodiment of the rod holder shown FIG. 1 .

FIG. 7 is a top view of FIG. 6 .

FIG. 8 is a side view of FIG. 7 .

FIG. 9 is a cross-sectional view taken along line 9-9 in FIG. 7 .

FIGS. 10-13 are top perspective views of other embodiments of the holder of FIG. 1 .

FIGS. 14-16 are perspective views of other embodiments of a rod holder embodying the present invention.

FIGS. 17-23 are perspective views of the holder of FIG. 1 attached to a formboard.

FIGS. 24-30 are views of the holder of FIG. 1 , showing the adjustment feature for adjusting the height of a rod while maintaining the required engagement of the rod in the holder.

FIGS. 31-32 shows examples of application of the holder of FIG. 1 .

FIG. 33 is perspective view of the threads in the holder being cut by the rod threads.

FIGS. 34-47 are perspective views, some in cross-sections, of other embodiments of the holder with hex nuts molded into the holder.

FIGS. 48-50 illustrate the breakaway feature of the holder when attached to the formboard.

FIG. 51 is a cross-sectional view of the holder after separation from the formboard, showing access to a bottom hex nut in the holder.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1 , a top perspective view of a rod holder 2 embodying the present invention is disclosed. The holder 2 is preferably molded of plastic or other suitable material. The rod holder 2 preferably includes several rod openings 4 for receiving an end portion of a rod, as shown in FIG. 22 . The openings have different diameters to advantageously accommodate different size rods, for example ½ in., ⅝ in. and ¾ in. so that a single holder can be used for any of the three size rods, thereby simplifying manufacturing and stocking considerations. The openings 4 are preferably arranged around a central opening 6, for example at 120 degrees apart. The openings 4 are offset from a vertical central axis through the opening 6. The top of the openings 4 are preferably flush with a platform 5, which advantageously provides a flat surface for supporting an anchor, such as a metal plate, hex nut, etc., that is attached to the rod being held in one of the rod openings 4.
The holder 2 includes leg portions 8 to advantageously elevate the openings 4 above a concrete formboard. The leg portions include screw holes 10 and nail holes 12. It should be understood that the openings 10 may also be used for nails and the opening 12 for screws.
Referring to FIG. 2 , a top view of the holder 2 is shown. The rod openings include two sets of segmented threads 14 and 16. The segmented threads 14 are vertically spaced above the segmented threads 16 to advantageously provide a lever distance to hold the end of the rod securely in the opening. Shoulders 18 are disposed inside the openings 4 to serve as stop members for the bottom of the rod being screwed into the opening. The shoulders 18 advantageously ensure that the bottom of the rod is at a specified distance above the formboard to seal the rod from the outside of the concrete to prevent possible corrosion from the environment. The shoulders 18 are disposed below the lower segmented threads 16 and preferably at the bottom of a slot 46 (see FIG. 28 ).
The central opening 6 further includes a bottom wall 20 with a smaller opening 22 for receiving a screw for attaching the holder to the formboard. The bottom wall 20 is advantageously breakable or tearable from the wall of the opening 6 to allow the screw to separate from the holder when the formboard is removed after the concrete has cured, allowing the screw to stay attached to the formboard, thus avoiding the extra work of cutting off the screw from the concrete structure.
The screw holes 10 similarly include a bottom wall 24 and a smaller opening 26. The bottom wall 24 is advantageously breakable or tearable to allow the screw to separate from the walls of the holes 10 when the formboard is removed after the concrete has cured, allowing the screws to stay attached to the formboard, thus avoiding the extra work of cutting off the screws from the concrete structure.
Each nail hole 12 includes a smaller diameter portion between the top and bottom of the holes for friction holding the nails prior to driving the nails to the formboard so that the holder 2 can be pre-supplied with nails held in the nail holes 12.
Referring to FIG. 3 , the holder 2 is shown in side-view. A center post 30 houses the central opening 6. The center post 30 includes a sidewall 32 with slotted openings 34 to advantageously allow trapped air to escape during concrete pouring. A top wall 36 provides the platform 5 for an anchor, such as a hex nut, which is threaded to the rod supported by the holder 2 in one of the rod openings 4. The wall 36 is advantageously vertically and horizontally spaced from the nail holes 12 and the screw holes 10 to avoid the anchor from touching the nail or screw and possibly causing corrosion. An anchor, such as a metal plate as disclosed in U.S. Pat. No. 9,097,001 can extend beyond the top wall 36 and be safely spaced from the nail holes 12.
The bottoms of the leg portions 8 and the center post 30 are preferably on the same level for a stable and flat attachment to the formboard.
Referring to FIG. 4 , a bottom perspective view of the holder 2 is shown. The center post 30 is attached to the sidewalls 38 of the rod openings 4. The leg portions 8 each includes sidewalls 40 attached to the respective sidewalls 38 of the rod openings 4. The sidewalls 40 are also joined to the walls 42 of the screw holes 10 and the walls 44 of the nail openings 12. The sidewalls 38 include slotted openings 46 to allow visual inspection of the extent of travel of the bottom of the rod inside the openings 4. The rod is advantageously adjusted up or down while the bottom of the rod is visible through the slot 46 to ensure that the rod remains threaded to the threads 14 and 16 for a stable connection. Engagement of the threads 14 and 16 provides a stable and secure placement of the rod to prevent inadvertent movement during concrete pouring when concrete vibrators are typically used to eliminate air bubbles. The bottom of each of the slotted openings 46 is preferably at the same level as the top of shoulders 18. The top end of each of the slotted openings 46 is below the lower segmented threads 16, ensuring that the rod engages all the segmented threads when its bottom end is visible through the slotted opening 46. The sidewalls 38 also open into each rod opening 4.
Referring to FIG. 5 , a perspective cross-sectional view through the screw hole 10 and the central opening 6 is shown. The bottom walls 24 and 20 are breakable or tearable at 122 to allow the bottom walls 24 and 20 to separate from the walls of the openings 10 and 6 during removal of the formboard after the concrete has cured to allow the screws to stay attached to the formboard, thereby eliminating the need to cut off the screws from the concrete structure. The connection 122 may have the same or thinner thickness than the thickness of the bottom walls 20 and 24.
Referring to FIG. 6 , a top perspective view of another embodiment of a rod holder 48 is disclosed. The holder 48 includes the rod openings 4 with top edges disposed above a base 49. The openings 4 are arranged around the central opening 6. The leg portions 8 elevate the base 49 above the formboard. The nail holes 12 and the screw holes 10 are provided in the leg portions 8.
Referring to FIG. 7 , a top view of the holder 48 shows the stop members 50 that provides the same function as the shoulders 18 in the holder 2. The central opening 6 includes the smaller opening 22. The screw holes 10 and the nail holes 12 are shown.
Referring to FIG. 8 , a side view of the holder 48 shows the bottoms of the leg portions 8 and the center post 30 preferably on the same level for a stable and flat attachment to the formboard. The bottoms of the slotted openings 46 are preferably on the same level as the stop members 50.
Referring to FIG. 9 , a cross-section of the holder 48 shows the central opening 6, the screw hole 10 and the nail hole 12. The bottom portions of the openings 6 and 10 are the same as shown in FIG. 5 .
Referring to FIG. 10 , a top perspective view of another embodiment of a rod holder 52 is shown. A ring-shaped base 54 supports the openings 4 and 6 with wall members 56. The leg portions 8 are attached to the periphery of the base 54.
Referring to FIG. 11 , a top perspective view of another embodiment of a rod holder 58 is shown. The holder 58 is the same as the holder 52, except for the addition of the platform 5, which provides a larger top surface than afforded by the top edges of the openings 4 for stabilizing an anchor, such as a metal plate or hex nut, attached to the rod in one of the openings 4.
Referring to FIG. 12 , a top perspective view of another embodiment of a rod holder 60 is disclosed. The platform 5 is substantially triangular to accommodate the nail holes 12.
Referring to FIG. 13 , a top perspective view of another embodiment of a holder 62 is shown. The holder 62 is similar to the holder 2, except that the screw holes 10 are open toward the inside.
Referring to FIGS. 14 and 15 , a top perspective view and a bottom perspective view, respectively, of another embodiment of a rod holder 64 is disclosed. The holder 64 includes a single rod opening 4 and a center post 30 that include the same features as found in the holder 2 and the other embodiments. The rod opening 4 is supported by wall members 66 to the base 49. The leg portions 8 include the nail holes 12 and the screw holes 10. Wall members 68 provide reinforcement to the wall members 66.
Referring to FIG. 16 , a perspective view of another embodiment of a rod holder 68 is disclosed. The holder 68 is similar to the holder 64, except that the wall members 68 and the bottom edges of the wall members 66 are disposed above the base 49. This arrangement advantageously provides for more open spaces through which concrete can flow to avoid trapping bubbles during the concrete pour.
Referring to FIGS. 17 and 18 , holder 2 is shown attached to a formboard 70 with screws 72 in the screw holes 10 or with nails 74 in the nail holes 12.
Referring to FIG. 19 , a bottom perspective view of an embodiment of a rod holder 74 similar to the holder 2 without the center post 30 is shown.
Referring to FIG. 20 , a bottom perspective view of an embodiment of a rod holder 76 similar to the holder 2 without the nail holes 12 and the screw holes 10 in the leg portions 8. Only the center post 30 is provided for attaching the holder to the formboard with the screw 72.
Referring to FIGS. 21-23 , another embodiment of a rod holder 78 is shown. The holder 78 is similar to the holder 2, except that only one rod opening 4 is provided. The rod opening 4 is off-centered. A threaded rod 80, which can be a bolt or an anchor rod, is shown threaded in the opening 4. The rod 80 is threaded to the upper thread segments 14 and the lower thread segments 16. Thread ribs 82 extend vertically below the lower thread segments 16 (see also FIG. 4 ). The ribs 82 are cut by the rod threads and serve to provide frictional engagement with the rod threads to hold the rod securely in place.
Referring to FIG. 24 , the rod 80 has engaged the upper segmented threads 14 and the lower segmented threads 16. The bottom of the rod 80 will become visible through the slotted opening 46 with further advancement of the rod 80 into the opening 4. The top of the rod 80 is at its highest level of adjustment when the rod engages the lower segmented threads. The rod 80 can be advanced until it hits the shoulder 18, cutting the rib threads 82 along the way. The top of the rod 80 is at its lowest position of adjustment when it hits the shoulder 18. The thread of the rod 80 will have cut the rib threads 82 between the highest level and the lowest level of the rod. The top of the rod is advantageously adjustable between the highest level and the lowest level before pouring concrete. Adjustments to the rod provides an advantageous way of making the top of a number of rods supported in the respective holders at the same level before concrete is poured.
Referring to FIG. 25 , the bottom of the rod 80 is between the bottom thread 16 and the shoulder 18.
Referring to FIG. 26 , the bottom of the rod 80 engages the shoulder 18, preventing the rod from going any further.
Referring to FIGS. 27 and 28 , the bottom 84 of the rod 80 is visible through the slot 46. This indicates that the rod has engaged the threads 14 and 16, since the top of the slot 46 is below the lower threads 16. Engaging the threads 14 and 16 provides the minimum depth of the rod inside the opening 4 for a stable and secure connection. FIG. 28 is a cross-sectional view of the holder 2, showing the top of the slot 46 being below the lower segmented threads. When the rod is visible in the slot 46, the rod is also engaged with the thread ribs 82, providing additional holding strength in the opening 4 in securing the rod in place. The thread ribs 82 are configured to be cut by the rod threads as the rod advances downwardly, providing additional threads to hold the rod. Vertical adjustment of the rod within the limit of the slot 46 advantageously ensures the continued engagement of the threads 14 and 16 with the rod for a stable and secure connection.
Referring to FIG. 29 , the bottom 84 of the rod 80 is visible through the slot 46. The bottom of the rod is not engaging the shoulder 18.
Referring to FIG. 30 , the bottom 84 of the rod 80 is visible through the slot 46 and is in contact with the shoulder 18.
Referring to FIG. 31 , the holder 2 may be used to position a screed chair 86 above the formboard 70 prior to concrete pouring. The rod 80 may be adjusted within the range of visibility through the slot 46 to ensure that the top of the rod 80 is at the same level as the other rods supporting another screed chair.
Referring to FIG. 32 , the holder 2 is used to support the rod 80 with a coupler 88. The rod 80 is used as an anchor rod, which is to be attached to a load via the coupler 88 after the concrete 90 has cured. The coupler 88 has a cap 92 to keep the concrete slurry from entering the inside of the coupler.
Referring to FIG. 33 , the thread segments 14 and 16 are made larger than the rod threads so that the rod threads cut into the thread segments 14 and 16 when the rod 80 is installed, thereby providing a tight fit for a stable connection inside the opening 4. Surface areas 94 and 96 on the thread 14 had been cut by the thread of the rod 80 when rod was installed in the opening 4.
Referring to FIGS. 34-36 , another embodiment of a rod holder 98 is disclosed. The holder 98 is similar to the holder 2, except that the holder 98 has a single opening 4 provided with a hex nut 100, which provides the function of the segmented threads 14 and 16. The hex nut 100 also advantageously serves as an anchor body. The hex nut 100 is molded into the holder such that the top surface 104 of the hex nut 100 is exposed and only the corners 102 are covered in plastic. The corners formed by the intersection of the top surface 104 and the flat side 106 of the hex nut remain exposed so as to grab the concrete and generate a breakout or shear cone when load is applied to the hex nut. Other threaded anchor bodies, such as those disclosed in U.S. Pat. Nos. 8,943,777 and 9,097,001 may also be used in lieu of or in addition to the hex nut 100.
Referring to FIG. 35 , the opening 4 continues into an opening 108 in the body of the holder 98. Stop member 50 (see FIG. 36 ) is disposed across the bottom of the opening 108. Thread ribs 82 may be provided on the inside surface of the opening 108 to advantageously provide additional attachment of the rod 80 to the holder. The inspection slotted opening 46 may be provided in the wall of the opening 108 as a visual check to ensure that the rod is fully threaded to the nut 100.
Referring to FIGS. 36-37 , the thread ribs 82 are provided on the inner surface of the opening 108.
Referring to FIGS. 38-39 , the center post 30 is provided to the holder 98. The shoulder 18 at the top of the center post 30 provides the stop members for the bottom of the rod 80.
Referring to FIG. 40 , the embodiments of FIGS. 34-39 are further modified as a rod holder 110 with the addition of hex nuts 112 and 114 underneath the hex nut 100. The hex nuts 100, 112 and 114 are preferably stacked on top of each other and have different hole diameters, the hex nut 100 having the largest diameter, the hex nut 114 having the smallest diameter, and the hex nut 112 having an intermediate size diameter. With different size hex nuts, the holder is configured to accept different diameter rods. The hex nuts are advantageously molded into the plastic body of the holder 110.
Referring to FIGS. 41-43 , the embodiments of FIGS. 34-39 are modified as a rod holder 116 wherein the hex nut 100 is positioned off-center from the central opening 6. The opening 50 below the nut 110 may be provided with the thread ribs 82.
Referring to FIGS. 44-47 , the embodiments of FIGS. 40-43 are modified as a rod holder 118 wherein the hex nuts 100, 112 and 114 are positioned around the central opening 6. Each of the openings of the nuts 100, 112 and 114 continue to the opening 108 (see FIG. 42 ) where the inside surface of the opening may be provided with the thread ribs 82. The holder 118 may include the center post 30, as shown in FIG. 45 , or without it, as shown in FIGS. 46-47 .
Referring to FIG. 48 , the holder 110 is attached to the formboard 70 through the center post 30. The screw 72 goes through the openings 6 and 22 and the head is supported on the bottom wall 20 (see FIG. 5 ). The head of the screw 72 is supported on the bottom wall 20, which is supported underneath by a circumferential member 120, which is spaced from the wall of the opening 6, except at a circumferential connection 122, which is thinner than the thickness of the wall. The bottom wall 20 with the underlying member 120 advantageously supports the head of the screw 72.
Referring to FIG. 49 , after the concrete 90 has cured, the formboard is separated from the concrete. The bottom wall 20 is torn from the wall of the opening 6 at the connection 122, with the screw 72 remaining attached to the formboard. The breakaway feature of the holder 110 advantageously eliminates the task of cutting off the screw from the cured concrete were the screw to remain attached to the holder after removal of the formboard.
The breakaway feature of central opening 6 works the same way with the opening 10 in the leg portions 8. For example, referring to FIGS. 5 and 23 , the head of the screw 72 is supported by the bottom wall 24, which is supported by the circumferential member 120. The bottom wall 24 is attached to the wall of the opening 10 at the connection 122 with a thickness of material smaller than the thickness of the wall of the opening 10. When the formboard is separated from the concrete, the screw stays attached to the formboard and separates the bottom wall 24 from the wall of the opening 10.
The breakaway feature described above works the same way for all the other embodiments of the holder for attaching the holder to the formboard.
Referring to FIGS. 50-51 , the central opening 6 in the center post 30 may be used to access the bottom hex nut 114 to attach another rod 124 for attaching a load below the concrete 90. After the formboard is removed, with the screw 72 tearing away the bottom wall 20 in the central opening 6, the opening 60 becomes accessible through which the rod 124 may be inserted and threaded to the hex nut 114. The rod 124 may be used to support a load below the concrete structure.
Although the embodiments shown includes one or three rod openings 4, it should be understood that two or more than three openings may be used.
It should be understood that the various features shown in a particular combination in an embodiment of the rod holder are equally applicable and may be interchanged with the other features shown in another configuration of the rod holder to arrive at different configurations even though not specifically disclosed in combination with the other embodiments.
While this invention has been described as having preferred design, it is understood that it is capable of further modifications, uses and/or adaptations following in general the principle of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains, and as may be applied to the essential features set forth, and fall within the scope of the invention or the limits of the appended claims.

Claims

I claim:

1. A rod holder for being embedded in concrete, comprising:

a) a body including a first opening for holding an end portion of a threaded rod, the first opening including an upper portion and a lower portion, the upper portion including threads for threaded connection with the threaded rod; and

b) the body including a vertical slot in a sidewall of the lower portion of the first opening, the slot for making visible an end portion of the threaded rod to ensure minimum threaded connection of the threaded rod in the upper portion while the threaded rod is adjusted vertically.

2. The rod holder as in claim 1, wherein the first opening is offset from a vertical central axis of the body.

3. The rod holder as in claim 1, wherein the body includes leg portions to elevate the body above a formboard.

4. The rod holder as in claim 1, wherein the threads are segmented.

5. The rod holder as in claim 1, wherein shoulder portion extends into the first opening to provide a stop for a bottom of the threaded rod.

6. The rod holder as in claim 3, wherein the body includes a center post with a second opening, the center post extends to the formboard.

7. The rod holder as in claim 6, wherein:

a) the second opening includes a bottom wall with a third opening for receiving a screw for attaching the holder to the formboard; and

b) the bottom wall is breakable from the center post with the screw when the formboard is removed.

8. The rod holder as in claim 3, wherein:

a) the leg portions each includes a second opening with a bottom wall with a third opening for attaching the holder to the formboard with a screw; and

9. The rod holder as in claim 1, wherein:

a) the slot includes a top end below the upper portion of the first opening; and

b) vertical ribs are disposed inside the lower portion of the first opening to engage the threaded rod.

10. The rod holder as in claim 1, wherein 1, wherein:

a) the body includes a top wall; and

b) the first opening includes a sidewall extending upwardly from the top wall.

11. The rod holder as in claim 10, wherein the slot extends above the top wall.

12. The rod holder as in claim 1, wherein:

a) the body includes a second opening for holding an end portion of another threaded rod; and

b) the second opening includes a diameter different from the first opening.

13. The rod holder as in claim 1, wherein the body includes openings for nails for attaching the body to the formboard.

14. The holder as in claim 3, wherein the leg portions include openings for screws for attaching the body to the formboard.

15. The holder as in claim 1, wherein the upper portion of the first opening includes nut molded into the body.

16. A rod holder for being embedded in concrete, comprising:

a) a body including a first opening with a first diameter and a second opening with a second diameter for holding an end portion of a first threaded rod with the first diameter in the first opening or a second threaded rod with the second diameter in the second opening; and

b) the first diameter being smaller than the second diameter.

17. The rod holder as in claim 16, wherein:

a) the first opening includes a first upper portion and a first lower portion, the first lower portion includes a vertical first slot in a sidewall of the first lower portion to make visible an end portion of the first threaded rod to ensure minimum threaded connection of the threaded rod in the first upper portion while the first threaded rod is adjusted vertically;

b) the second opening includes a second upper portion and a second lower portion, the second lower portion includes a vertical second slot in a sidewall of the second lower portion to make visible an end portion of the second threaded rod to ensure minimum threaded connection of the second threaded rod in the second upper portion while the second threaded rod is adjusted vertically.

18. The rod holder as in claim 16, wherein the body includes leg portions to elevate the body above a formboard.

19. The rod holder as in claim 16, wherein the first upper opening the second upper portion are threaded.

20. The rod holder as in claim 16, wherein a first nut and a second nut are molded in the first upper portion and the second upper portion, respectively.

21. The rod holder as in claim 17, wherein the first lower portion and the second lower portion include respective vertical ribs to engage the respective first threaded rod and the second threaded rod.

22. The rod holder as in claim 16, wherein the body includes a center post with a third opening, the center post extends to the formboard.

23. The rod holder as in claim 22, wherein:

a) the third opening includes a bottom wall with a fourth opening for receiving a screw for attaching the holder to the formboard; and

24. The rod holder as in claim 18, wherein:

a) the leg portions each includes a third opening with a bottom wall with a fourth opening for attaching the holder to the formboard with a screw; and

25. A rod holder for being embedded in concrete, comprising:

a) a plastic body including leg portions to elevate the body above a formboard, and a center post with a first opening, the center post extending to the formboard;

b) a first nut and a second nut disposed in the first opening, the first nut being above the second nut;

c) the first opening including a bottom wall with a second opening for receiving a screw for attaching the holder to the formboard, the bottom wall being breakable from the center post with the screw when the formboard is removed; and

d) the first nut for holding an end portion of a first threaded rod, the second nut for holding an end portion of a second threaded nut inserted into the first opening from below when the formboard is removed.

26. The rod holder as in claim 25, wherein a third nut is disposed in the first opening between the first nut and the second nut.

27. The rod holder as in claim 25, wherein the first nut has a larger diameter than the second nut.