1. Field of the Invention
The present invention relates to the manufacture of reinforced concrete. In particular the present invention relates to reinforced concrete wherein the rebar within the reinforced concrete is secured with a plastic tie fastener or a substantially similar device. Furthermore, the present invention relates to a method for manufacturing reinforced concrete using plastic tie fasteners or a substantially similar device. The present invention also relates to devices for securing rebar in reinforced concrete.
2. Description of the Related Art
The process of manufacturing steel reinforced concrete begins by forming a two or three dimensional grid of steel rebar around which concrete is poured. The individual lengths of rebar 10 are secured to one another to form this grid. Currently the industry standard is that the lengths of rebar are secured to one another at the grid intersections either by wrapping metal (usually steel) wire 12 around all lengths of rebar which form the grid at the intersections or by securing the grid intersections with spring steel wire clips (see FIGS. 1a, 1b and 2).
If metal wires 12 are used to prepare the grid, the free ends of the metal wire are twisted to tension the tie, securing the crossed bars in place. The free ends of the tie wire are then cut off or bent away from the concrete surface above the twist.
If the spring steel wire clips are used, the intersections are held together by the spring force of the spring steel wire clips.
If the concrete product is to be placed in a hostile environment (such as salt water, basic or acidic soil, etc.), the additional step of coating the metal tie wires or spring steel wire clips with some sort of protective coating or of using stainless steel metal tie wires must be taken.
There are a few drawbacks of the present uses of steel wire 12 and/or steel spring clips. The first drawback is the added time required by a construction worker to twist the free ends of the metal wires to tension the ties. Furthermore, the twisting of the wire fatigues the metal wire 12 at the twist site. This could cause the wire to break and allow the rebar 10 to become unsecured either prior to the pouring of concrete or even worse after the concrete has been poured. If the rebar becomes unsecured after the concrete has been poured the concrete may not have the reinforced strength that is required.
Another drawback of using metal wire ties is that the act of the construction worker attaching a machine to twist the ends of the wire tie, or the act of twisting the wire tie by hand is a time consuming task. Furthermore, the act of twisting wires requires an amount of area next to the rebar to twist the wire. Many times there are so many rebars 10 used to reinforce the concrete that there is little room between adjacent rebars to twist the steel wire 12.
Another drawback, which was alluded to above, is that the steel wires 12 or clips will rust if the concrete product is placed in a hostile environment. The rusting may weaken the overall structure and or produce unsightly stains on the structure. Rusting of the steel wire or clips cannot be completely avoided, but can be inhibited to some degree by coating the wires or clips with a protective coating. The extra coating step is costly and not always successful due to incomplete coating of the wires, having a twisted end which is difficult to completely coat, and if the end is removed or breaks off during the process an exposed end is left.
The present invention relates to the manufacture of reinforced concrete structures wherein plastic tie fasteners are used to secure the rebar structure within the concrete structure. Furthermore, the present invention relates to a method of securing rebar by using plastic tie fasteners. The plastic tie fasteners are looped about the rebar bars and tightened using a unidirectional force. The plastic tie fasteners can be looped and tightened via hand or an applicator or tensioning apparatus. The plastic tie fasteners offer the unexpected advantages of strength, flexibility, and ease of use to the reinforced concrete industry. Furthermore, the plastic tie fasteners do not rust or require rust retardant coatings. Still furthermore, the present invention prescribes a rebar securing apparatus comprising a plastic strip with a means for securing an end of said plastic strip in a looped configuration. The securing apparatus"" means for securing can be a ratcheting or slip resistant receptacle. Furthermore, the means for securing can be designed to disallow the loop from becoming larger or can be designed to allow the loop to become larger without damaging the securing apparatus.
The present invention provides a multitude of advantages which include, but are not limited to being incapable of rusting and staining a concrete structure, decreasing the amount of time required to secure rebar bars, an ease of use due to a simple technique for tightening the loop of the plastic tie fastener about the rebar, requiring only one hand of a construction worker to attach the plastic tie fastener to the rebar, and decreasing construction costs.