[0001] The present invention is directed to a bolster, and more particularly, to a slab bolster that can be used in concrete construction.

BACKGROUND

[0002] Bolsters are commonly used in the construction industry to support rebar, post tension cables, wire mesh or other reinforcements (collectively termed "reinforcing material" herein) at a desired position during a concrete pour. However, many existing bolsters must either be cut to length, or a plurality of modular sections must be connected together and built up to provide a bolster of the appropriate length. Such systems are relatively time and labor intensive in order to provide a bolster of the desired length. In addition, many existing bolsters are relatively expensive to manufacture.

SUMMARY

[0003] In one embodiment the present invention is directed to a bolster that has a frangible portion such that it can be manually broken to thereby be quickly and easily adjusted to the desired length. In addition, the bolster may in some cases be made by extrusion, providing cost savings. In particular, in one embodiment the invention is a slab bolster including a longitudinally-extending spine and a plurality of legs coupled to the opposite sides of the spine and extending away from the spine. The slab bolster has a frangible portion along which the slab bolster is configured to be manually broken to allow the slab bolster to be manually separated into at least two parts.

BRIEF DESCRIPTION OF DRAWINGS

[0004] Fig. 1 is an upper perspective view of one embodiment of the slab bolster of the present invention;

[0005] Fig. 2 is an upper perspective view of a part of the slab bolster of Fig. 1, shown after breaking along the frangible connections;

[0006] Fig. 3 is a detail view of one of the slab bolsters of Fig. 2;

[0007] Fig. 4 is a top view of the slab bolster of Fig. 3;

[0008] Fig. 5 is a side view of the slab bolster of Fig. 3; [0009] Fig. 6 is an end view of the slab bolster of Fig. 3, nestably stacked with a plurality of other slab bolsters;

[0010] Fig. 7 is an upper perspective view of an alternate slab bolster;

[0011] Fig. 8 is an upper perspective view of another alternate slab bolster;

[0012] Fig. 9 is an upper perspective view of yet another slab bolster;

[0013] Fig. 10 is an upper perspective view of another slab bolster;

[0014] Fig. 11 is an upper perspective view of an upper slab bolster;

[0015] Fig. 12 is an upper perspective view of an alternate upper slab bolster;

[0016] Fig. 13 is an upper perspective view of two slab bolsters of Fig. 3, shown in conjunction with rebar positioned thereon; and

[0017] Fig. 14 is an upper perspective view of the system of Fig. 13, shown in conjunction with two upper slab bolsters of Fig. 11 and additional rebar positioned thereon.

DETAILED DESCRIPTION

[0018] With reference to Figs. 1-6, in one embodiment the slab bolster, generally designated 10, has generally an inverted "V" shape in end view, having a longitudinally extending spine 12 and a plurality of legs 14 coupled to opposite sides of the spine 12, extending downward away from the spine 12 at an angle. In one embodiment, the spine 12 is generally rectangular in end view/cross-section (see Fig. 6), and each leg 14 is also generally rectangular in cross-section such that each leg 14 is shaped generally as a rectangular prism. The legs 14 can be spaced apart at regular intervals to thereby define a plurality of openings 16 positioned between adjacent legs 14. The openings 16 are generally square in front view in the illustrated embodiment.

[0019] The openings 16 may extend for a significant distance along the longitudinal directi on/dimension (length) L (Fig. 3) of the slab bolster 10 to allow poured concrete to easily flow through the openings 16 and around the slab bolster 10, to thereby minimize voids in the finished concrete product. In one case, the openings 16 extend for at least a majority of the length L of the slab bolster 10 or at least about 70 percent of the length L of the slab bolster 10. The spine 12 can extend generally continuously an entire length of the bolster 10, and in the illustrated embodiment includes a plurality of protrusions 18 spaced along the length thereof and extending upwardly from the spine 12, defining a plurality of recesses 20 therebetween. However, the protrusions 18/recesses 20 are optional and can be omitted, as shown for example in the slab bolster embodiment of Figs. 8 and 10.

[0020] As shown in Fig. 1, the slab bolster 10 in its starting configuration can have one or more frangible portions 21 along which the slab bolster 10 is configured to be manually broken to allow the slab bolster 10 to be manually separated into at least two parts or slab bolsters 10 (three of which are shown in Fig. 2). The frangible portions 21 can be an area/location of reduced thickness (such as formed by scoring or removing material from the slab bolster 10 at that location) and/or an area of weakness (such as formed by pre deformed or pre-stressed areas, or adding/using a different type of material or impurities at the location of the frangible portion 21 etc.) compared to adjacent areas of the slab bolster 10. The force required to break the frangible portions 21 may be sufficiently high such that the frangible portions 21 are not inadvertently broken during shipping and storage, but not so high that the bolsters 10 not able to be manually broken at the frangible portions 21. In one case the force required to break the frangible portions 21 can be greater than about 15 lbs. and/or less than about 50 lbs., and is about 351bs in once case.

[0021] Each frangible portion 21 can extend around an entirety, or at least about 50% in one case, or at least about 80% in another case, of the outer surface of the spine 12 to provide or define a clean break path. In one case, the frangible portions 21 can be positioned at regular intervals along the length of the un-broken slab bolster 10, for example every six inches in one case, or every twelve inches in another case, although the spacing of the frangible portions 21 can be varied as desired. In one embodiment, each frangible portions 21 is located away from the legs 14, and in one case can be located at mid-point between adjacent legs 14 and formed only or primarily in the spine 12, although the frangible portions 21 can be located at other positions as desired.

[0022] The frangible portions 21 enable the slab bolster 10 to be easily, quickly and manually snapped to length. In particular, during use it may be desired to have the slab bolster 10 extend generally the entire length, or perhaps slightly shorter, than the length of the form in which the slab bolster 10 is placed and/or concrete slab to be formed by pouring concrete into the form. The frangible nature of the slab bolster 10 enables the slab bolster 10 to be easily snapped to length by, in one case, simply positioning the slab bolster 10 in the desired position and manually snapping/breaking at the desired predetermined location 21, thereby eliminating the need for taking measurements, cutting to length with a tool, building up to the desired length, etc. [0023] In one embodiment, each leg 14 is generally straight and extends at a constant angle with the spine 12 relative, for example, to a height H dimension/direction (Fig. 3) of the slab bolster. When each leg 14 is straight, the included angle A of each leg 14 (Fig. 6) can be, for example between about 10 degrees and about 65 degrees, or more particularly between about 30 degrees and about 55 degrees, to provide desired strength and height while minimizing material usage. The height of the bolster 10 along direction H (excluding the height of the protrusions 18) can vary between about one-quarter inch and about five inches or other sizes as desired, and more particularly in one case between about one inch and three inches.

[0024] Each leg 14 can have a length dimension oriented parallel to the longitudinal direction L, a height dimension H _L oriented in a plane of each leg 14 and (in the case of straight legs 14) oriented perpendicular to the length dimension L (i.e. extending at an incline or angle in the illustrated embodiment) and a thickness dimension T oriented perpendicular to the length dimension L and the leg height dimension H _L . The thickness dimension T can, in one case, be the smallest dimension of each leg 14. In addition, in one embodiment the thickness dimension T is constant along an entirety, or at least a majority, of a length of each leg 14. In other words, each leg 14 can have a uniform thickness T in a direction perpendicular to an outer surface of the leg 14.

[0025] The distal or bottom of each leg 14 may be tapered to an edge or area of reduced width 22 in the width direction W, as best shown in Fig. 6, to reduce contact area between the bolster 10 and the deck surface or form during use. In particular, since the bolster 10 can rest on the deck surface 26 during the concrete pour, the distal or bottom end of each leg 14 may become visible in the end concrete product, particularly in tilt-up construction. Thus it may be desired to minimize surface area along the edge 22. In one case, the bolster 10 may lack any supports or other vertically-oriented components, that extend down toward the deck, other than the legs 14.

[0026] In one case, the bolster 10 is shaped and configured to be nestably stackable, as shown in Fig. 6. In particular, the inner surfaces of the bolster 10 can generally correspond in shape to the outer surfaces of the bolster 10 such that the bolster 10 is nestably stackable. This enables the bolsters 10 to be compactly stacked for storage, shipping or the like.

[0027] The size and configuration of the legs 14/openings 16 can be varied as desired. For example, as shown in Fig. 7, the dimension of both the legs 14 and the openings 16 in the length direction L can be shorter as compared to the embodiment shown in Figs. 1-6. In yet another embodiment shown in Fig. 8, each leg 14 can taper down to a smaller length at its distal end such that each leg 14 is generally triangular shaped in front view, to potentially provide materials savings. In this case, then, each leg 14 can have a length dimension that varies along its height HL. This design can also minimize contact with the deck surface 26 at the distal end of each leg 14 which can be desirable for aesthetic purposes as noted above in the context of the tapered edge 22. In yet another embodiment shown in Fig. 9, the upper ends of the legs 14/openings 16 may be curved, which may provide increased strength. The bolster 10 can also be shaped as a generally inverted "U" as shown in Fig. 10. In this case each leg 14 may be curved and extend downwardly from the spine 12 at a variable angle. Moreover, in this case each leg 14 may have the same thickness as the spine 12 (where each leg 14 joins the spine 12 and/or along an entirety of the leg 14/spine 12) such that each leg 14 smoothly transitions into/with the spine 12.

[0028] Fig. 11 illustrates another embodiment in which the bolster 10 includes a foot 24 positioned at the distal end of each leg 14 extending between, continuously in one case, two or more legs or each leg 14 to couple the legs 14 together. The feet 24 enable the slab bolster of Fig. 11 to be stacked upon other slab bolsters 10 positioned therebelow, as shown in Fig. 14, and will be described in greater detail below. Each foot 24 can also have a frangible portion (not shown) that is located at a corresponding longitudinal position of a frangible portion 21 located in the upper portion of the slab bolster 10 (i.e. the spine 12) to enable the slab bolster 10 to be snapped to length. Thus the bolster 10 of Fig. 11 (and also the bolster 10 of Fig. 10) can be considered an upper bolster 10 that can be stacked on an uneven surface, like rebar and/or other bolsters 10, where the feet 24 provide a stabilizing surface.

[0029] Fig. 12 illustrates another upper bolster 10 where the outer surfaces/comers of the openings 16 and the upper and lower ends of the legs 14 are curved, which man provide increased strength. The upper bolsters 10 of Figs. 10-12 may lack the tapered surfaces/edge 22 along the lower edges, since the upper bolsters 10 are spaced away from the deck surface 26 during use. In contrast, the bolsters 10 of Figs. 1-9 lack the feet 24 and can be considered lower or base bolsters.

[0030] Each bolster 10 can have a generally uniform cross-section, for the most part, such that each bolster 10 can be formed by extrusion with some additional processing steps in some cases which in some circumstances may be considered to be post-extrusion processing. Thus, the slab bolsters 10 can be made of, in one case, an extrudable material such as polymers, plastics, thermoplastics, including polycarbonate-ABS or glass filled propylene, or other materials which exhibit low water absorption, relatively high strength and relatively high impact resistance. Extrusion can be a more inexpensive production method compared to others such as injection molding, and can allow the slab bolster 10 to be extruded to any desired length for the specific desired application. In addition, rather than having to assemble multiple pieces to create a larger single piece, the present bolster 10 begins with a larger piece which can be easily snapped, at one or two locations, to provide the desired length. For example, the bolster 10 can be provided in lengths of at least ten feet, or at least about twenty feet, which are sufficient to provide a single continuous bolster for most concrete pours, although of course the length can be varied as desired.

[0031] The basic shape of each bolster 10 can be formed or extruded as a generally inverted "V" or "U," and the openings 16 can be formed by removing materials from the side panels of the "V" or "U." For example, in the embodiment of Figs. 1-6, a vertical "guillotine-style" cutting mechanism can be utilized to form the openings 16 by removing materials from the side panels in a vertical plane. In this case, a vertically-oriented/residual side surface 28, as best shown in Figs. 3 and 5 can result from the vertical cutting process. Alternately, the side panels of the extruded shape can have generally rectangular holes 16 knocked or formed therein by a cutting mechanism acting in an angle perpendicular to the side panels, to result in openings 16 as shown in the embodiments of Figs. 10-12. The recesses 20 (and thereby the protrusions 18) on the spine 12 can be formed by removing material from the spine 12, or compressing the spine 12, to thereby define the recesses 20 and protrusions 18 (by material which is not removed or compressed). The frangible portions 21 can be formed by scoring or removing material or the use of different materials or impurities, etc. during or after the extrusion process.

[0032] The slab bolster 10 can be extruded (which includes pultruded) by passing the raw material of the slab bolster 10, under pressure (for example from a ram), through a die having the desired cross-sectional shape of the slab bolster 10. Various equipment can be used for the extrusion, for example a screw extrusion machine (single or double screw), an extrusion press, direct or indirect extrusion equipment, vertical or horizontal extrusion equipment, hydraulic or mechanical drive extrusion equipment, hydrostatic extrusion equipment, extrusion equipment which uses a puller, pultrusion equipment, or the like. [0033] In order to utilize the slab bolsters 10 of Figs. 2-12, the slab bolsters 10 can first be snapped to the desired length and then one or more of the lower slab bolsters 10 can be positioned on a horizontal surface, slab or deck surface 26, as shown in Fig. 13. The deck surface 26 can constitute the base surface for a subsequent concrete pour, such as the base surface of a concrete form. It thus may be desired to position reinforcing material 30, such as rebar, post-tension cables, wire mesh 30 a predetermined distance above and parallel to the deck surface 26. Thus, once the lower slab bolsters 10 are positioned, in one case in parallel rows as shown in Fig. 13, the reinforcing material 30 can be positioned on the spines 12 of the lower slab bolsters 10. The reinforcing material 30, shown as rebar in the illustrated embodiment, can be positioned in associated recesses 20 to generally align and retain the rebar 30 in place.

[0034] If desired, the lower slab bolsters 10 can be secured to the underlying deck surface 26 and/or each other. In addition, the reinforcing material 30 if desired can be secured or tied (e.g. by wire or the like) to the underlying slab bolsters 10 by wire ties or the like (not shown). The concrete can then be poured, and the slab bolsters 10 and reinforcing material 30 remain in place and remain in the poured concrete slab such that the reinforcing material 30 adds strength and durability to the finished concrete product. After pouring and curing, the poured slab can remain in place in the horizontal position or, if desired, can be released from its form and raised to a vertical or other configuration for use in tilt-up construction or the like.

[0035] If it is desired to have two or more levels of reinforcing material 30, the upper slab bolsters 10 can be utilized and stacked on the first row of reinforcing material 30, as shown in Fig. 14. In this embodiment, the feet 24 of the upper slab bolster 10 can span the gap between adjacent rebars 30 so that the upper slab bolsters 10 can be stably positioned above the lower or first row of rebar 30/slab bolsters 10. If desired, an additional set of reinforcing material 30 can then be stacked on top of the upper slab bolsters 10, and additional rows of upper bolsters 10 and reinforcing material 30 can then be stacked as desired.

[0036] Having described the invention in detail and by reference to the various embodiments, it should be understood that modifications and variations thereof are possible without departing from the scope of the claims of the present application.

[0037] What is claimed is: