The present invention relates to dowel devices suitable for concrete pavement construction and, more particularly, to a field-assembly dowel basket assembled from standardized components on an as-needed, where-needed basis.
Dowels are embedded into joints between adjacent slabs of concrete to prevent vertical displacement between the slabs to maintain a smooth pavement surface and increase the strength of the concrete in the region of the joint. While the dowels are embedded in the joints to prevent excessive vertical displacement between the slabs, they may be designed to allow a small amount of horizontal separation as well as vertical and lateral displacement between the slabs to relieve internal stress to accommodate drying shrinkage and thermal expansion and contraction of the slabs. This permits a normal amount of slab movement to prevent excessive cracking while still maintaining a sufficiently smooth top surface of the pavement.
In pavement construction, a series of dowels are typically installed at each expansion joint between adjacent sections or slabs of pavement. A long structure known as a dowel basket is typically used to hold a line of dowels in place at the edge of a section of pavement before the slab is poured. The basket positions each dowel so that half of the dowels will be embedded in the concrete slab to be poured, with the other half to be embedded in the adjacent slab to be poured next. An expansion joint is typically formed into the joint or cut into the dried concrete above the dowel basket at each expansion joint. The pavement is thus constructed section after section, and in some cases mile after mile, with a line of dowels held in place by a dowel basket embedded into the concrete at each expansion joint. A range of pavement structures are constructed in this manner, such as roads, bridge decks, airport runways, sidewalks, floors, buildings, and so forth. The term “pavement” for this purpose includes walls, roofs, ceilings, caisson, and other structures as well as roads, bridges, floors and sidewalks. Pavement is typically manufactured from concrete, but may be made from any suitable material poured in sections.
Constructing a concrete road in this manner requires the dowel baskets to be continually manufactured and made available at the construction site as section after section, and mile after mile, of road is poured. In conventional concrete road construction, the dowel baskets are welded together at a welding shop and then transported, typically by truck, to the construction site. For a long road construction project, a series of welding jobbers may be contracted along the route as the road is constructed. Dowel basket fabrication can be a significant logistical challenge and a major cost factor in concrete road construction. A similar concern can arise in any project utilizing large numbers of joined concrete sections, such as high-rise buildings, sidewalks, bridges, dams, and so forth. At times, dowel basket fabrication may become the critical path item, causing construction crews to sit idle waiting on dowel basket delivery before construction of the project can continue. As a result, there is a persistent need for cost effective solution to dowel basket manufacturing to facilitate concrete pavement construction.
The present invention meets the needs described above in a field-assembly dowel jacket and basket for concrete construction configured for in-the-field assembly from standardized components, including dowels, dowel jackets, wire frames, and inline plastic connectors. This allows a number of standard components to be conveniently transported and stored on construction sites to facilitate on-site assembly of the dowel baskets on an as-needed, where-needed basis. Since the dowel basket components are much smaller than assembled baskets, they can be shipped in bulk and stored much more cost effectively. Standardization of components allows mass production, bulk shipping, consolidated inventory management, and avoids the need for ad hoc fabrication for each construction site. On-site dowel basket assembly eliminates welding from the dowel basket fabrication process, avoids shipping of fabricated dowel baskets, and allows assembly of dowel basket by construction workers as opposed to highly skilled welding shops.
The dowel jacket has a crab-shaped elongated body with a leg-clip structures on each end. The dowel clips into the elongated body, while a frame wire clips into each leg-clip structure. The same dowel jacket may be configured to interchangeably support rectangular plate dowels, elongated diamond-shaped plate dowels, and/or round bar dowels. The frame wires have a “W” shape similar to those described in U.S. Pat. No. 10,443,194, which is incorporated by reference. The leg-clip structures of the dowel jacket support the frame wires sufficiently to eliminate the need for “T” connectors and shipping wires utilized in the dowel baskets described in U.S. Pat. No. 10,443,194, thus reducing the number of parts, simplifying the assembly, and increasing the rigidity of the dowel basket.
In a representative embodiment, two frame wires support two dowel jackets, each supporting a dowel to form a dowel basket section. The dowel jacket includes two leg-clip structures, each firmly attaching the dowel jacket to a respective frame wire. Each leg-clip structure includes three clips features including two leg clips, which attach to risers of the frame wire, as well as a central clip feature that clips to the crossbar of the frame wire, to securely attach the frame wire and dowel to the dowel jacket. Multiple dowel basket sections are joined together by inline connectors connecting adjacent frame wires to fabricate an elongated dowel basket. The dowel basket is positioned to span an expansion joint between adjacent concrete slabs as the slabs are poured to fabricate concrete structures, such as roads, bridge decks, floors, and the like.
Embodiments of the invention may be realized in a dowel jacket and a field-assembly dowel basket, components for a field-assembly dowel basket, a method for constructing a concrete road or other structure using the field-assembly dowel baskets, and a road or other structure constructed with the field-assembly dowel baskets. Rather than the conventional approach of fabricating dowel baskets at welding shops and transporting the fabricated dowel baskets to the construction site, embodiments of the present invention provide field-assembly dowel baskets assembled at the construction site from a small number of standard components.
The field-assembly dowel basket is assembled from a small number of component parts, including dowels jackets, dowels supported by the dowel jackets, “W” shaped frame wires that clip into the dowel jackets to support the dowels within the jackets, and inline connectors that join the frame wires of basket sections together. The dowels, dowel jackets, frame wires, and inline plastic connectors can therefore be manufactured off-site as unassembled components and transported in bulk to the construction site, where they are stored in bulk and assembled in the field on an as-needed, where needed basis. Once assembled, the dowel basket is positioned at the edge of a first concrete slab prior to pouring the slab. The dowel basket holds the dowels in place about midway up the thickness of the slab. A concrete form is positioned around the dowels near the centerline of the dowel basket. The first slab is poured so that about half of the dowels extend into the slab and half extend beyond the slab. After the first slap sets, the form is removed and a second slab is poured over the portions of the dowels that extending beyond the first slab. An expansion joint is typically formed or cut over the dowel basket at the intersection of the two slabs. See U.S. Pat. No. 10,443,194, which is incorporated by reference.
In an illustrative embodiment, each field-assembly dowel basket is formed from a number of dowel basket sections that each removably hold two dowels in place. Any number of dowel basket sections can be connected together with incline connectors to form a dowel basket of desired length, which typically extends laterally across the road or other structure under construction. Each dowel basket section includes a pair of frame wire side components connected to each other by a dowel jacket supporting a dowel. The same dowel jacket can be used to interchangeably support an elongated diamond-shaped plate dowel, and/or a rectangular plate dowel, and/or a bar dowel. The frame wire sides are spaced apart from each other by the dowel jackets. Each frame wire is formed form a single “W” section of wire. As a result, only one type of wire component is required, the “W” shaped frame wire side component. In addition, only one type of connector is required, the inline connector used to join the frame wires of adjacent basket sections together.
In an alternate embodiment, clips are used to attach a round dowel bar (i.e., a dowel bar with a round cross-section) to a dowel jacket. The dowel bar may be may be attached to the top side or the bottom side of the dowel jacket. These dowel jackets may be configured to only support round dowel bars, or they may be further to interchangeably support elongated diamond-shaped and/or rectangular plate dowels. For each of these embodiments with a dowel bar or a plate dowel attached to the bottom side of the dowel jacket, tape may attached below the dowel enclosing the bottom side of the dowel jacket to prevent the concrete from hardening the dowel to the dowel jacket. This accommodates relative movement of the concrete slabs without cracking the concrete.
The dowel jacket may be fabricated from an injection molded plastic, such as polypropylene, polyethylene, polyethylene terephthalate (PET), polyvinyl chloride (PVC) or any other suitable material. As an option, the dowel jackets may be fabricated from high-strength plastic, such as acrylonitrile butadiene styrene (ABS) or polycarbonate. The frame wires may be manufactured from the type of spring steel wire typically used in wire mesh for concrete reinforcement. The inline connectors may be made from a suitable inexpensive plastic such as polypropylene, polyethylene, PET or PVC.
While specific dimensions may vary as a matter of design choice, the following dimensions are typical for an illustrative embodiment. The drawings are generally shown to scale. The rectangular plate dowels are typically 12 inches (305 mm) long, 2 to 2.5 inches (51 to 64 mm) wide, and ¼ to ½ inch (6.4 to 12.7 mm) thick. The round bar dowels are typically 15 to 18 inches long (381 to 457 mm) and ⅜ to ¾ inch (9.5 to 19 mm) in diameter. The dowel-to-dowel spacing is typically 18 to 24 inches (457 to 610 mm). The side-to-side spacing between the “W” wire frames is typically 12 inches (305 mm). The basket supports the dowels midway in the slab to be poured (e.g., 4 inches (102 mm) for 8-inch (203 mm) thick slab) above the base where the concrete is to be poured. The wire frame components may be made from ¼ to ⅜ inch (6.4 to 9.5 mm) diameter concrete reinforcement steel wire. In an illustrative embodiment, the plate dowels may be stamped from mild steel ¼ to ½ (6.4 to 12.7 mm) inch thick. The frame wires may be 5/16-inch (8 mm) diameter spring steel wires bent into the desired shape.
While the representative embodiments shown in the figures include dowel assemblies in each section, dowel basket sections with different numbers of dowel assemblies may be fabricated. For example, dowel basket sections that have one dowel assembly in each section may be fabricated, dowel basket sections that have three dowel assemblies in each section may be fabricated, and so forth. In addition, while tape enclosing the bottom side of the dowel jacket is only illustrated for the dowel bar embodiments in
Although the field-assembly dowel baskets have been illustrated in the context of horizontal pavement construction, it will be appreciated that the dowel basket is well adapted for, but not limited to, road and floor construction. It should be appreciated that the field-assembly dowel baskets can be used for any concrete joint of sufficient size regardless of its intended purpose or orientation. For example, the invention is equally applicable to joints in concrete roads, sidewalks, floors, walls, ceilings, abutments and other structures. Those skilled in the art will appreciate that the foregoing describes preferred embodiments of the invention and that many adjustments and alterations will be apparent to those skilled in the art within the spirit and scope of the invention as defined by the appended claims.
This application claims priority to U.S. Provisional Pat. App. Ser. No. 63/027,925 filed May 20, 2020; U.S. Provisional Pat. App. Ser. No. 63/063,027 filed Aug. 7, 2020; and U.S. Provisional Pat. App. Ser. No. 63/183,051 filed May 2, 2021; which are all incorporated by reference.
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63063027 | Aug 2020 | US | |
63183051 | May 2021 | US |