Patent Application
20050224690
(1) Field of the Invention
The present invention relates to concrete pads having drainage holes, and in particular to concrete pads made using a form that includes a plurality of spaced, vertically aligned conduits joined by spacers, and having removable caps covering their upper ends.
(2) Description of the Prior Art
Concrete pads, i.e., a layer of poured concrete having a given length, width and thickness, are highly durable and are widely used for a variety of applications including walkways, driveways, and the like. Normally, concrete pads are formed by preparing the surface on which the pad is to be poured, and then constructing a removable form or frame about the periphery of the area.
The interior of the form is then filled with a pourable concrete mix and the upper surface of the poured concrete is leveled with the upper surface of the form, normally by drawing a screed supported by the form over the concrete to remove any excess concrete and to fill any voids. As the concrete sets, the upper surface of the pad can be finished with a float over the surface to form a smooth surface, or brooming the surface to form a brushed surface. The form is then removed after the concrete has cured.
One disadvantage of concrete pads is the fact that water impinging on the pad, e.g., rainwater, is prevented from absorption into the soil beneath the pad, resulting in runoff that can cause flooding and soil erosion. As a result, the use of concrete pads in sensitive areas may be prohibited.
Two approaches are commonly used to address this problem. First, instead of using on-site formed pads, the area may be covered with revetment pads, which are essentially preformed concrete pads that are produced in a mold having projections that create openings in the pads. Normally, several revetment pads will be placed side-by-side to cover the selected area. This approach is considerably more expensive than pouring a single concrete pad, and provides an inferior covering since the individual pads may shift over time.
The second approach to this problem is to pour the pads with porous concrete instead of conventional concrete. Porous concrete is of limited value in that only a small percentage of water may penetrate the pad, particularly during a hard or heavy rain. In addition, porous concrete is considerably more expensive than conventional concrete.
Thus, there remains a need for a concrete pad that has the attributes of a conventional concrete pad, while still permitting drainage of water through the pad. In particular, the cost of the pad should be comparable to conventional concrete pads, and should permit sufficient water to flow through the pad, even with heavy rainfall.
Generally, the present invention relates to a concrete form of a unique configuration, to a concrete pad incorporating the form in-situ, and to a method of using the concrete form to produce a concrete pad with water drainage holes.
More specifically, the concrete form is comprised of a plurality of spaced vertical conduits that are joined together by spacers. For example, the conduits may be arrayed in a rectangular or diamond-shaped configuration with the conduits being held in a fixed configuration by the spacers. The conduits are of a length that corresponds to the desired thickness of the concrete pad, which is usually about 3 to 6 inches.
The form is manufactured to a standard dimension offsite, e.g., by injection or vacuum molding from a plastic, or by molding from other material such as cardboard. The form may be cut to the desired dimensions and configuration on site, if the size of the desired concrete pad is less than the size of the preformed form. Alternatively, a plurality of forms may be joined together, if the dimensions of the concrete pad are greater than the dimensions of the form.
The conduits include upper ends with removable covers or caps to prevent concrete from entering the conduits during formation of the concrete pad. These caps are removed after the concrete is poured to allow water to flow downwardly through the conduits for absorption into the soil beneath the pad. The caps may be in the form of pull-off caps with optional pull tabs, or may be punch-out caps that can be removed by striking the cap downwardly to break the connection of the cap with the conduit and then removing the cap.
The spacers may be of various configurations so long as the spacer has ends that attach to conduits. Preferably, the spacers are integrally formed with the conduits. The upper surface of the spacers should not project above the upper ends of the conduits, and will preferably be at a level slightly below the conduit upper ends. The lower surface of the spacers can project above or below the lower ends of the conduits.
The cross-sectional shape of the conduit may be circular, or of various other shapes depending upon the aesthetic appearance desired. For example, the conduit may have a cross-section that is in the shape of a star, a half-moon, a triangle, etc. All of the conduits may have the same cross-sectional configuration, or conduits of different configurations may be combined in a single form. The cross-sectional area of a given conduit may vary. Normally, however, the cross-sectional area will be from about 0.25 to about 2.0 inches, with about 4 to about 100, and more commonly about 6 to about 60 conduits being present in each square foot of form.
The vertical height of the form is not critical to the invention. The vertical height may be, for example, from about 2 to about 6 inches. For instance, most concrete pads are poured to a thickness of about 3.5 inches, referred to in the trade as a 4 inch pad, due to the use of 2×4s as framing lumber. The forms may also be stacked for use in pouring thicker forms. In this application, only the caps on the upper form will be used during pouring of the concrete.
The form may be reinforced prior to formation of the concrete pad by attaching reinforcing rods, or rebar, to the form. The form may include attachment means for this purpose. These attachment means may be in the form of hooks, loops, holes, slots, etc., which will normally be used to attach the reinforcement rod to the form.
In the production of the concrete pad, one or more forms, cut to size if needed, are positioned on a prepared surface, e.g., a generally horizontal surface that has been smoothed to receive the form. The form may be secured in place by anchors that are attached to the form and driven into the ground. If desired, a removable outer frame may be constructed around the form.
Concrete is then poured into the form until the concrete covers the form and is at a level at least up to the upper ends of the conduits. The concrete is then leveled, e.g., with-a screed, so that the upper surface of the concrete is in a plane with the upper ends of the conduits. The concrete may then be smoothed with a float and, optionally brushed.
After the concrete has cured, the conduit caps are removed. The resultant concrete pad has all of the attributes of a conventional concrete pad in terms of durability and support for objects placed on the pad. However, due to the conduits, water that falls or flows onto the surface of the pad will be able to drain through the conduits into the soil beneath the pad, eliminating the primary objection to such pads and permitting their use instead of the less desirable and more expensive alternatives.
In the following description, terms such as horizontal, upright, vertical, above, below, beneath, and the like, are used solely for the purpose of clarity in illustrating the invention, and should not be taken as words of limitation. The drawings are for the purpose of illustrating the invention and are not intended to be to scale.
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Certain modifications and improvements will occur to those skilled in the art upon a reading of the foregoing description. It should be understood that all such modifications and improvements have been deleted herein for the sake of conciseness and readability but are properly within the scope of the following claims.
