Flexible grid and predominantly concrete mat employing same

Abstract

A predominantly concrete mat comprises a concrete slab having two longitudinal edges and two transverse edges and having relatively thicker portions and relatively thinner portions, which include relatively thinner portions among the longitudinal and transverse edges, and a flexible grid embedded in the concrete slab. The flexible grid, which is polymeric, is molded so as to have longitudinally extending members and transversely extending members. End portions of specific ones but not all of the longitudinally extending members of the flexible grid extend into and nearly or completely through the relatively thinner portions along the transverse edges of the concrete slab. End portions of specific ones but not all of the transversely extending members of the flexible grid extend into and nearly or completely through the relatively thinner portions along the longitudinal edges of the concrete slab.

Description

TECHNICAL FIELD OF THE INVENTION

This invention pertains to a flexible grid, which is useful to connect concrete blocks of a predominantly concrete mat, and to a predominantly concrete mat employing such a flexible geogrid.

BACKGROUND OF THE INVENTION

A flexible, molded, polymeric grid and a predominantly concrete mat employing the flexible grid are disclosed in U.S. Pat. No. 7,048,469 B1, the disclosure of which is incorporated by reference herein. As disclosed therein, the flexible grid has longitudinally extending members and transversely extending members and is embedded in a concrete slab having relatively thicker portions and relatively thinner portions. The relatively thicker portions define blocks, which are connected by the relatively thinner portions. The longitudinally and transversely extending members of the flexible grid connect the blocks to one another, when the concrete slab is broken along the relatively thinner portions, whereby the predominantly concrete mat is articulated.

As disclosed in U.S. Pat. No. 7,048,469 B1, the concrete slab has relatively thinner portions along its longitudinal and transverse edges. Consequently, if the flexible mat is not approximately centered when the concrete slab is made, one of the members bounding the flexible mat, along one of its longitudinal and transverse edges, can become embedded within the relatively thinner portion along the corresponding edge of the concrete slab and can weaken the same portion sufficiently for the weakened edge to crumble. Similarly, the relatively thinner portions meeting at a corner of tje concrete mat can be so weakened.

In an earlier form, an articulated, predominantly concrete mat is disclosed in U.S. Pat. No. 5,108,222, the disclosure of which is incorporated by reference herein. In an improved form, an articulated, predominantly concrete mat is disclosed in U.S. Pat. No. 6,612,776 B1, the disclosure of which is incorporated by reference herein. As disclosed in these patents, such a mat has numerous uses in retarding earth erosion due to wind, water, or both and in lining a driveway, a parking area, or an emergency roadway.

SUMMARY OF THE INVENTION

This invention provides a flexible grid adapted to be embedded in a concrete slab having two longitudinal edges and two transverse edges and having relatively thicker portions and relatively thinner portions including relatively thinner portions among the longitudinal and transverse edges. The flexible grid has longitudinally extending members and transversely extending members. The longitudinally and transversely extending members meet at nodes.

As provided by this invention, specific ones of the longitudinally extending members have end portions extending beyond the end portions of the others of the longitudinally extending portions and beyond whichever of the transversely extending members are endmost. Moreover, specific ones of the transversely extending members have end portions extending beyond the end portions of the others of the transversely extending portions and beyond whichever of the longitudinally extending members are endmost.

In one contemplated embodiment of this invention, wherein all of the longitudinally extending members have end portions extending beyond whichever of the transversely extending members are endmost, while the end portions of the specific ones of the longitudinally extending members extend further than the other ones of the longitudinally extending members beyond whichever of the transversely extending members are endmost. Moreover, all of the longitudinally extending members have end portions extending beyond whichever of the transversely extending members are endmost, while the end portions of the specific ones of the transversely extending members extend further than the other ones of the transversely extending members beyond whichever of the longitudinally extending members are endmost.

This invention also provides a predominantly concrete mat comprising a concrete slab having two longitudinal edges and two transverse edges and having relatively thicker portions and relatively thinner portions, which include relatively thinner portions among the longitudinal and transverse edges, and a flexible grid, as described above. The flexible grid is embedded in the concrete slab so that the end portions of the specific ones of the longitudinally extending members of the flexible grid extend into and nearly or completely through the relatively thinner portions along the transverse edges of the concrete slab and so that the end portions of the specific ones of the transversely extending members of the flexible grid extend into and nearly or completely through the relatively thinner portions along the longitudinal edges of the concrete slab.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary, isometric view of a concrete slab, in which a flexible grid embodying this invention and defining flexible members extending longitudinally and transversely is embedded.

FIG. 2, on a smaller scale, is a fragmentary, schematic plan of an injection mold, in which the flexible grid illustrated in FIG. 1 is being molded. FIG. 3 is a greatly enlarged, sectional detail taken along line 3-3 of FIG. 4, in a direction indicated by arrows. FIG. 4, on a similar scale, is a fragmentary plan of a portion of the flexible grid.

FIG. 5, on a larger scale, is a fragmentary cross-section of a casting mold, in which the concrete slab is being cast in an inverted orientation, as seen after an upper portion of the casting mold has been raised, a lower portion of the casting mold has been filled partially with a concrete mix, and the flexible grid has been placed on the concrete mix.

FIG. 6, on a similar scale, is a fragmentary, isometric view of an articulated, predominantly concrete mat, as made from the concrete slab having the embedded grid, when the concrete slab having the embedded grid is broken along thin areas so as to define concrete blocks, which are connected to one another by the flexible members of the flexible grid.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

As illustrated in FIG. 1, an intermediate article 10 in the manufacture of an articulated, predominantly concrete mat, which is similar to the articulated, predominantly concrete mat disclosed in U.S. Pat. No. 7,048,469 B1, supra, comprises a rectangular, concrete slab 20 and a flexible grid 30, which is embedded in the concrete slab 20.

As illustrated in FIG. 5, when the concrete slab 20 is cast in a casting mold 60, which has a lower portion 62 and an upper portion 62, the lower portion 62 of the casting mold 60 is filled partially with a concrete mix M, onto which the flexible grid 30 is placed. Thereupon, the lower portion 60 is filled completely with the concrete mix M, whereby the flexible grid 30 is embedded in the concrete mix M. Thereupon, the upper portion 62 is lowered so as to close the casting mold 60, in which the concrete mix M is cured.

The concrete slab 20 is cast, in an inverted orientation relative to its illustrated orientation, so as to have relatively thinner portions 22 extending longitudinally and transversely and so as to have relatively thicker portions 24, which are separated from one another by the relatively thinner portions 22. The relatively thinner portions 22 include relatively thinner portions 22a along the longitudinal edges of the concrete slab 20 and relatively thinner portions 22b along the transverse edges of the concrete slab 20.

As illustrated in FIG. 7, the concrete slab 20 is breakable along the relatively thinner portions 22, so that the relatively thicker portions 24 become discrete, concrete blocks 40 connected to one another by flexible members 32 of the flexible grid 30, which remains embedded in the respective blocks 40, whereby an articulated, predominantly concrete mat 50 is provided. The flexible members 32 meet and are joined at nodes 34. Preferably, the flexible members 32 have circular cross-sections, but the flexible members 32 may have oval, rectangular, or other cross-sections.

So as to facilitate breaking of the concrete slab 20 along the relatively thinner portions 22, the concrete slab 20 has spaced holes, which include holes having circular mouths and holes having square mouths, along the relatively thinner portions 22. The relatively thinner portions 22 may be sufficiently thin to enable the concrete slab 20 to be thus broken by its own weight if and when the concrete slab 20 is lifted from its edges. Alternatively, the concrete slab 20 may be thus broken by a person wielding a suitable tool, such as an adze.

As exemplary dimensions, all of which are approximate, the concrete slab 20 may have a width of twenty-four inches and a length of forty-eight inches, the relatively thinner portions 22 may have a thickness of three-eights inch, the relatively thicker portions 24 may have a thickness of one inch, the flexible geogrid 30 may have two inch square openings, which are defined by the flexible members 32, and the respective blocks 40 may be four inches square.

The flexible grid 30 may be injection molded, as illustrated schematically in FIG. 2, so as to have longitudinally extending members 32 and transversely extending members 34. The longitudinally and transversely extending members 32, 34, meet at nodes 36, which are spaced precisely and uniformly (e.g. by two inches) from one another, both longitudinally and transversely.

As illustrated in FIG. 2 and other views, all of the longitudinally extending members 32 have end portions 36 extending beyond whichever of the transversely extending members 34 bound the flexible grid 30. Moreover, specific ones of the longitudinally extending members have end portions 36a extending further than the end portions 36 of the others of the longitudinally extending portions 32 and further than the transversely extending members 34 at the boundaries of the flexible grid 30.

As illustrated in FIG. 2 and other views, all of the transversely extending members 34 have end 38 portions extending beyond whichever of the longitudinally extending members 32 bound the flexible grid 30. Moreover, specific ones of the transversely extending members 34 have end portions 38a extending further than the end portions 38 of the others of the transversely extending portions 34 and further than the longitudinally extending members 32 at the boundaries of the flexible grid 30.

As illustrated in FIG. 2 and other views, the specific ones of the longitudinally extending members 32 having the end portions 32a extending further are separated from one another and from the transversely extending members 34 at the boundaries of the flexible grid 30 by one or more of the longitudinally extending members 32. Moreover, the specific ones of the transversely extending members 34 having the end portions 34a extending further are separated from one another and from the longitudinally extending members 32 at the boundaries of the flexible grid 30 by one or more of the transversely extending members 34.

As illustrated in FIG. 2 and FIG. 5, the end portions 32a extending further extend into and nearly or completely through the relatively thinner portions 22a along the longitudinal edges of the concrete slab 20. Moreover, the end portions 34a extending further extend into and nearly or completely through the relatively thinner portions 22b along the transverse edges of the concrete slab 20.

Claims

1. A flexible grid adapted to be embedded in a concrete slab having two longitudinal edges and two transverse edges and having relatively thicker portions and relatively thinner portions, which include relatively thinner portions among the longitudinal and transverse edges, the flexible grid having longitudinally extending members and transversely extending members, the longitudinally and transversely extending members meeting at nodes, wherein specific ones of the longitudinally extending members have end portions extending beyond the end portions of the others of the longitudinally extending portions and beyond whichever of the transversely extending members are endmost, and wherein specific ones of the transversely extending members have end portions extending beyond the end portions of the others of the transversely extending portions and beyond whichever of the longitudinally extending members are endmost.

2. The flexible grid of claim 1, wherein all of the longitudinally extending members have end portions extending beyond whichever of the transversely extending members are endmost, while the end portions of the specific ones of the longitudinally extending members extend further than the other ones of the longitudinally extending members beyond whichever of the transversely extending members are endmost, and wherein all of the longitudinally extending members have end portions extending beyond whichever of the transversely extending members are endmost, while the end portions of the specific ones of the transversely extending members extend further than the other ones of the transversely extending members beyond whichever of the longitudinally extending members are endmost.

3. The flexible grid of claim 1, wherein the specific ones of the longitudinally extending members are separated from one another and from whichever of the transversely extending members are endmost by one or more of the longitudinally extending members, and wherein the specific ones of the transversely extending members are separated from one another and from whichever of the longitudinally extending members are endmost by one or more of the transversely extending members.

4. The flexible grid of claim 2, wherein the specific ones of the longitudinally extending members are separated from one another and from whichever of the transversely extending members are endmost by one or more of the longitudinally extending members, and wherein the specific ones of the transversely extending members are separated from one another and from whichever of the longitudinally extending members are endmost by one or more of the transversely extending members.

5. A predominantly concrete mat comprising a concrete slab having two longitudinal edges and two transverse edges and having relatively thicker portions and relatively thinner portions, which include relatively thinner portions among the longitudinal and transverse edges, and a flexible grid according to claim 1, 2, 3, or 4, wherein the flexible grid is embedded in the concrete slab so that the end portions of the specific ones of the longitudinally extending members of the flexible grid extend into the relatively thinner portions along the transverse edges of the concrete slab and so that the end portions of the specific ones of the transversely extending members of the flexible grid extend into the relatively thinner portions along the longitudinal edges of the concrete slab.

6. A predominantly concrete mat comprising a concrete slab having two longitudinal edges and two transverse edges and having relatively thicker portions and relatively thinner portions, which include relatively thinner portions among the longitudinal and transverse edges, and a flexible grid according to claim 1, 2, 3, or 4, wherein the flexible grid is embedded in the concrete slab so that the end portions of the specific ones of the longitudinally extending members of the flexible grid extend into and nearly or completely through the relatively thinner portions along the transverse edges of the concrete slab and so that the end portions of the specific ones of the transversely extending members of the flexible grid extend into and nearly or completely through the relatively thinner portions along the longitudinal edges of the concrete slab.