Water-permeable concrete pad and form

Abstract

A concrete pad with drainage holes is created using an in-situ form that is preferably biodegradable with a matrix of spaced, vertically aligned conduits having upper ends with removable caps and connector means connecting the conduits. The form is horizontally positioned at the area where the pad is to be created and concrete is poured into the form until the concrete surrounds the walls of all of the conduits and the upper surface of the concrete is in a plane with the upper ends of the conduits. After the concrete has cured, the caps are allowed to biodegrade or are removed to permit water to flow from the top of the pad through the conduits for drainage from the lower ends of the conduits into the soil beneath the pad.

Claims

1 . A concrete form for use in producing a concrete pad with an upper surface and a lower surface and a plurality of spaced drainage holes extending from the pad upper surface to the pad lower surface comprising: a) a matrix of spaced, vertical conduits having continuous side walls, upper ends and lower ends; b) connector means connecting said conduits; and c) caps covering said conduit upper ends, said form being an open-top form whereby concrete can be poured downwardly into said form onto said connector means and around the side walls of all conduits in said matrix. 2 . The form of claim 1 , wherein said form is made from a biodegradable material. 3 . The form of claim 1 , wherein said conduits and connector means are integrally molded. 4 . The form of claim 1 , wherein said conduits are truncated cones with integral caps. 5 . The form of claim 1 , wherein at least 50 percent of the length of said conduits projects above said connector means. 6 . The form of claim 1 , wherein said connector means is a continuous sheet having an upper surface with said conduits projecting upwardly from and being integral with said sheet. 7 . A concrete pad with a plurality of spaced drainage holes comprising: a) a form with a matrix of vertical conduits joined by a connector means, said conduits having continuous side walls, upper ends and lower ends; and b) concrete filling said form, said concrete surrounds the walls of all conduits in said matrix and having an upper surface in a plane with the upper ends of said conduits, whereby water can enter the upper ends of said conduits and drain through said conduits to beneath said pad. 8 . The concrete pad of claim 7 , wherein said form is made from a biodegradable material. 9 . The concrete pad of claim 7 , wherein said conduits have a circular cross-section. 10 . The pad of claim 7 , wherein said conduits are arrayed in a rectangular pattern. 11 . The pad of claim 7 , wherein said connector means is comprised of spacers with opposed ends attached to adjacent conduits. 12 . The pad of claim 7 , wherein said conduits and connector means are integrally molded. 4 . The pad of claim 7 , wherein said conduits are truncated cones with integral caps. 5 . The pad of claim 7 , wherein at least 50 percent of the length of said conduits projects above said connector means. 15 . A method of forming a concrete pad having drainage holes comprising: a) providing a form having a matrix of spaced, vertical conduits having continuous side walls, upper ends and lower ends, connector means connecting said conduits, and caps covering said conduit upper ends, said form being an open-top form whereby concrete can be poured downwardly into said form and around the side walls of all conduits in said matrix; b) horizontally positioning the form at the area where the pad is to be formed; and c) pouring concrete into said form until the concrete surrounds all of said conduits and the upper surface of the concrete is in a plane with the upper ends of said conduits; and 16 . The method of claim 15 , further including the step of removing said caps. 17 . The method of claim 15 , wherein said form is constructed of a biodegradable material. 18 . The method of claim 15 , wherein said connector means comprises vertically oriented rectangular spacers with opposed ends, said ends being attached to adjacent conduits. 19 . The method of claim 15 , wherein said conduits and connector means are integrally molded. 20 . The method of claim 15 , further including the step of attaching rebar to said form prior to pouring said concrete.
[0001] This application is a continuation-in-part application of and claims priority to U.S. application Ser. No. 10/822,372, filed Apr. 12, 2004. BACKGROUND OF THE INVENTION [0002] (1) Field of the Invention [0003] The present invention relates to concrete pads having drainage holes, and to a form for use in making such pads that includes a plurality of arrayed, vertically aligned connected conduits. In particular, the invention relates to forms that are constructed of a biodegradable material. [0004] (2) Description of the Prior Art [0005] 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. [0006] 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. [0007] 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 contamination of ponds, streams, rivers and other bodies of water. As a result, the use of concrete pads in sensitive areas may be prohibited. [0008] 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. [0009] The second approach to this problem is to pour the pads with porous concrete instead of conventional concrete. Porous concrete is difficult to finish and work with, requires special training, and has durability issues. In addition, porous concrete is considerably more expensive than conventional concrete. [0010] 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. SUMMARY OF THE INVENTION [0011] 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. [0012] More specifically, the concrete form is comprised of a matrix, i.e., an array of multiple rows and columns, of connected vertical conduits having upper ends that are in a plane with the upper surface of the concrete pad for intake of water and lower ends that are at or below the bottom of the concrete pad for discharge of water into the soil beneath the pad. [0013] The conduits may be arrayed in a multitude of configurations, including rectangular or diamond-shaped configurations, with the conduits being held in a fixed array by connectors or a common base. 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 connector may be a plurality of elongated spacers with opposed ends integral with arrayed conduits, or a continuous sheet of material having upper and lower surfaces with the conduits extending upwardly from the upper surface of the sheet. [0014] The form is manufactured to a standard dimension offsite from a plastic or molding from a biodegradable moldable material. Normally, the form will be molded by one of several known procedures, e.g., pressure molding, injection molding, or vacuum molding. 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. [0015] Where spacers are used as the connector means to join the conduits, each elongated spacer will have a length equal to the desired separation of adjacent conduits, with the ends of each spacer being attached to the wall of a conduit. For example, the spacers may be passed through slots or openings in the conduits. The spacers may be integrally formed with the conduits or attached in any known manner. [0016] The spacers may be of various configurations so long as the spacer has ends that attach to conduits. The upper surface of the spacers is at a level below the upper ends of the conduits. Preferably, the top of the spacers will not extend above the lower half of the conduits. That is, at least 50% of the length of the conduits will project above the spacers. The lower surface of the spacers can project above or below the lower ends of the conduits. [0017] Where the connector means is a continuous sheet of material having opposed upper and lower surfaces, the conduits are normally integrally formed with the sheet by extending spaced portions of the sheet upwardly to form vertical conduits that extend from an outwardly flared lower end joining the sheet to an upper end. If the sheet is of a moldable thermoplastic material, the upper ends of the conduits may include removable covers or caps. For example, a sheet with extended conduits can be vacuum formed from a thermoformable sheet or molded from a moldable material with the conduits extending up from the sheet that extends across the bottom of the form between the conduits. [0018] Preferably, the form is made from a biodegradable material, i.e., a material that will decompose under natural conditions within a short period of time, e.g., about twelve months, and preferably within about three months. Suitable biodegradable materials include cellulosic material such as cardboard, newspaper, straw waste, and the like, and biodegradable plastics. [0019] In order to prevent concrete from entering the interior of the conduits, it is necessary to cover the tops of the conduits during pouring of the concrete. If the form is a plastic form, the conduit tops can be covered with removable caps, optionally with pull tabs or by a thin material that can be punched out after the concrete has hardened. However, if the form is molded from a biodegradable material, the caps can simply be integrally molded with the conduit side wall. In this latter embodiment, the upper ends of the conduits, i.e., the caps, may be torn away during the latter steps of concrete pad formation, or the caps will naturally decompose over a short period of time once the pad is exposed to the elements, leaving the open conduits. [0020] When the form is a continuous sheet of material with upwardly projecting conduits, the upper surface of the sheet and the side walls of the conduits, along with any outer frame, define an area for receiving the concrete. In either configuration, the form is an open-top form, i.e., a form in which concrete can be poured downwardly across the entire form, and over the connector means and around the outer walls of all conduits in the matrix. [0021] 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 smaller the dimensions of the conduits, the more conduits will be used. [0022] 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. [0023] 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. [0024] In the production of the concrete pad using forms with detachable caps, 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 all or most of the form. [0025] Concrete is then poured into the form until the concrete covers the connector means and walls of the conduits up to the upper ends of the conduits and the top of the surrounding boards. Where the connector means is a continuous sheet joining the conduits, the concrete is poured onto the upper surface of the sheet until the concrete surrounds the outer walls of the conduits to the top of the form boards. 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 broomed. The removable caps are then pulled off of the conduit upper ends. [0026] If the form is made of a biodegradable material, e.g., molded cardboard, the tops of the conduits will be integrally molded with the conduit walls. For example, a form can be molded as a continuous sheet with upwardly projecting conical conduits. The lower edges of the conical conduits are integral with the sheet and the upper ends of the conduit walls extend over the conduit inner opening to form a cap or top. After the pad is produced, the caps or tops are brushed away or allowed to biodegrade to open the conduit interiors. [0027] The resultant concrete pad, manufactured with either type of form, 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 can 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. BRIEF DESCRIPTION OF THE DRAWINGS [0028] FIG. 1 is a perspective view of one embodiment of the form of the invention within a removable frame. [0029] FIG. 2 is a perspective view of a concrete pad formed by pouring concrete over the form of FIG. 1 . [0030] FIG. 3 is a top view of another embodiment of the form of the invention with the conduits in a diamond-shaped matrix. [0031] FIG. 4 is a top view of another embodiment of the invention in which the conduits have different cross-sectional shapes. [0032] FIG. 5 is a perspective of a segment of a form manufactured by molding a sheet of biodegradable material. [0033] FIG. 6 is a perspective of a segment of another form manufactured by molding a sheet of biodegradable material. [0034] FIG. 7 is a sectional side view of a part of the form of FIG. 1 . [0035] FIG. 8 is a sectional side view of a part of the form of FIG. 5 . [0036] FIG. 9 is a sectional side view of a part of the form of FIG. 6 . DETAILED DESCRIPTION OF THE INVENTION [0037] 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. [0038] As best shown in FIG. 1 , a first embodiment of form, generally 10 , is comprised of a plurality of vertical conduits 12 joined by spacers 14 in a rectangular matrix. Some of spacers 14 may include attachments 16 for positioning of rebar 18 . In the embodiment shown, attachment 16 is a V-shaped slot having a lower end approximately one-half the distance between the upper and lower surfaces of form 10 . As shown, form 10 is enclosed within a temporary frame 20 , which is removed after the poured concrete has cured. [0039] FIG. 2 illustrates a concrete pad, generally 30 , poured using the form illustrated in FIG. 1 . The upper ends of conduits 12 of in-situ form 10 are in a plane with the upper surface of pad 30 , so that water collected on the upper surface of pad 30 will flow through conduits 12 to the lower ends of the conduits to be absorbed by the soil beneath pad 30 . [0040] FIG. 3 illustrates another form 40 , which is similar to form 12 , except for the arrangement of conduits 42 , which are held in a diamond-shaped matrix by spacers 44 . It will be apparent to one skilled in the art that the conduits can be arrayed in any manner to meet the aesthetic and functional requirements of the user. As shown in FIG. 4 , the conduits in either form can also be of various cross-sectional shapes. While most conduits will likely be of a circular cross-section as shown at 50 , the conduit may have a triangular cross-section as shown at 52 , a half-moon shaped cross-section as shown at 54 , a star shaped cross-section as shown at 56 , a rectangular cross-section as shown at 58 , etc. [0041] FIG. 5 illustrates an alternative form, generally 70 , manufactured by molding, vacuum forming or thermoforming a sheet of material, preferably a biodegradable material, to create conduits 72 joined by spacers 74 , with the conduits and spacers extending upward from and being integral with the sheet. Caps 80 are integrally molded with the conduit side walls. The cost to manufacture this form is generally less. In addition, the weight of the concrete on the form base 76 and on the curvatures 78 at the lower ends of conduits 72 and spacers 74 serve to anchor the form in place. [0042] FIG. 6 illustrates another molded form, generally 82 , manufactured by molding a biodegradable cellulosic material to create conduits 84 which extend upwardly from a planar floor 86 . Conduits 84 are conically shaped with truncated tops, with their lower edges integral with floor 86 , and include caps or covers 88 are integrally molded with the conduit side walls. Form 80 is surrounded by temporary frame 90 . [0043] FIG. 7 is a sectional side view of a part of form 10 as shown in FIG. 1 illustrating vertical conduits 12 with removable caps 24 connected by spacers 14 . Reinforcing rod 18 is supported within attachment 16 , and anchor pin 22 in used to hold form 10 in place. [0044] FIG. 8 is a sectional side view of a part of form 70 as shown in FIG. 5 illustrating vertical conduits 72 with integral caps 80 connected by spacers 74 . [0045] FIG. 9 is a sectional side view of a part of form 82 as shown in FIG. 6 illustrating vertical conduits 84 with integral caps 88 projecting upward from floor 86 . [0046] Referring to FIGS. 1 and 2 , in the method of the present invention, form 10 is positioned in the desired location on the ground. A temporary frame 20 may be positioned around form 10 . The form may be reinforced by attaching rebar 18 to spacers 14 . Form 10 may be secured in place by anchors 66 . Concrete is then poured into the open-top form 10 over spacers 14 and around the walls of all conduits 12 in the matrix. The concrete is then leveled so that the upper surface of the concrete is in a plane with the upper ends of conduits 12 . After the concrete has cured, conduit caps 60 are removed so that any water that falls or flows onto the surface of pad 30 can escape through conduits 12 into the soil beneath the pad. After a period of time, if form 10 is made from a biodegradable material, form 10 decomposes, leaving only the concrete pad. [0047] Concrete pads can be produced in a similar manner using the forms illustrated in FIGS. 5 and 6 . With these forms, concrete is poured onto floors 76 or 86 , respectively, until the level on the concrete is in a plane with the tops of conduits 72 or 84 . Caps 80 or 88 are then removed by abrasion during finishing of the concrete, or biodegrade upon exposure to the outdoor elements. [0048] 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.

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    Publication numberPublication dateAssigneeTitle
    FR-2960568-A1December 02, 2011Sols SaMold for realizing concrete flooring to make concrete slabs or platforms for public transport, has hollow studs formed of biodegradable polymeric material such that studs are degraded when studs are in contact with water