KNITTED GEOTEXTILE

Abstract

A knitted geotextile includes a plurality of first strength yarns arranged in a first layer, each of the plurality of first strength yarns extending in a first direction, a plurality of second strength yarns arranged in a second layer, each of the plurality of second strength yarns extending in a second direction, a plurality of capillary active yarns arranged in at least one of the first layer or the second layer, and a plurality of knitting yarns interconnecting the plurality of first strength yarns, the plurality of second strength yarns, and the plurality of capillary active yarns.

Description

FIELD

The present disclosure relates generally to geotextiles, and more particularly, knitted geotextiles for use in the construction of roadways and other trafficked surfaces.

BACKGROUND

Geotextiles are used in the construction of roadways and other trafficked surfaces to provide three primary functions: separation of soil from aggregate; filtration to protect a drainage or aggregate layer from soil or fines intrusion; and stabilization by promoting load distribution through aggregate layers. Conventional geotextiles are typically formed as a woven fabric, which may fulfil these three primary functions. However, such geotextiles generally do not enhance drainage, which is another important factor in roadway design. Therefore, there is a need in the art for a geotextile that addresses the performance characteristics of separation, filtration, and stabilization while providing improved drainage to increase the service life of roadways and other trafficked surfaces.

SUMMARY

The present disclosure provides, in one aspect, a knitted geotextile including a plurality of first strength yarns arranged in a first layer, each of the plurality of first strength yarns extending in a first direction, a plurality of second strength yarns arranged in a second layer, each of the plurality of second strength yarns extending in a second direction, a plurality of capillary active yarns arranged in at least one of the first layer or the second layer, and a plurality of knitting yarns interconnecting the plurality of first strength yarns, the plurality of second strength yarns, and the plurality of capillary active yarns.

The present disclosure provides, in another aspect, a knitted geotextile including a plurality of strength yarns, a plurality of capillary active yarns configured to transport fluid in at least one of a first direction or a second direction, and a plurality of knitting yarns interconnecting the plurality of strength yarns and the plurality of capillary active yarns in a warp knit configuration. The first direction is a machine direction along which the knitted geotextile advances during manufacturing thereof, and the second direction is a cross-direction perpendicular to the machine direction.

The present disclosure provides, in another aspect, a knitted geotextile configured to enhance drainage of fluid between a trafficked surface and a subgrade soil. The knitted textile includes a plurality of capillary active yarns configured to transport fluid in at least one of a first direction or a second direction and a plurality of knitting yarns interconnecting the plurality of capillary active yarns in a warp knit configuration.

Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a knitted geotextile according to an embodiment of the present disclosure.

FIG. 2 illustrates a top view of a knitted geotextile of FIG. 1.

FIG. 3 illustrates a bottom view of the knitted geotextile of FIG. 1.

FIG. 4 illustrates a schematic view of the geotextile of FIG. 1 including a plurality of layers.

FIG. 5 illustrates a schematic cross-sectional view of a wicking yarn, which may be incorporated into the knitted geotextile of FIG. 1.

FIG. 6 illustrates a schematic cross-sectional view of an alternative wicking yarn, which may be incorporated into the knitted geotextile of FIG. 1.

FIG. 7 illustrates a schematic cross-sectional view of an alternative wicking yarn, which may be incorporated into the knitted geotextile of FIG. 1.

FIG. 8 illustrates a schematic cross-sectional view of an alternative wicking yarn, which may be incorporated into the knitted geotextile of FIG. 1.

FIG. 9 is a schematic cross-sectional view of a trafficked surface construction including the knitted geotextile of FIG. 1 disposed between an aggregate layer and a subgrade soil layer.

Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.

DETAILED DESCRIPTION

FIG. 1 illustrates a geotextile fabric or geotextile 10 according to an embodiment of the disclosure. The geotextile 10 comprises a knitted fabric, which may improve the fluid wicking capabilities of the geotextile 10 as described in greater detail below. The illustrated geotextile 10 may thus be referred to herein as a knitted geotextile and may be contrasted with a geotextile comprising a woven fabric (i.e., yarns or fibers that are interlaced, crossed intricately together, or formed as a perpendicular crisscross pattern).

The illustrated geotextile 10 includes a plurality of first strength yarns 14, a plurality of second strength yarns 18, a plurality of active capillary yarns or wicking yarns 22, and a plurality of knitting yarns 24. As shown in FIGS. 1 and 2, the first strength yarns 14 extend in a first direction 26, which in some embodiments may be a machine direction along which the geotextile 10 advances during manufacturing. As shown in FIGS. 1 and 3, the second strength yarns 18 extends in a second direction 30, which in some embodiments may be a cross-direction substantially perpendicular to the machine direction. In other embodiments, the first direction 26 and/or the second direction 30 may be angled relative to the machine direction and cross direction. In some embodiments, the first strength yarns 14 may extend in the second direction, and the second strength yarns 18 may extend in the first direction.

The first strength yarns 14 and the second strength yarns 18 may be formed from a polymer material. The polymer material and dimensions of the strength yarns 14, 18 in the illustrated embodiment may provide the geotextile 10 with a tensile strength of at least 10 kN/m as measured under the ASTM D4595 wide width tensile testing method, in both the first direction 26 and the second direction 30. In some embodiments, the tensile strength of the geotextile 10 in the first direction 26 and the second direction 30 may be at least 40 kN/m under ASTM D4595. In some embodiments, the tensile strength of the geotextile 10 in the first direction 26 and the second direction 30 may be at least 70 kN/m under ASTM D4595. In some embodiments, the tensile strength of the geotextile 10 in the first direction 26 and the second direction 30 may be between 70 kN/m and 80 kN/m under ASTM D4595. The polymer material of the strength yarns 14, 18 may include, but is not limited to, polypropylene, polyester, polyethylene, or polyamide. The material of the first strength yarns 14 and the second strength yarns 18 provides the overall strength for the geotextile 10. The material of the first strength yarns 14 and the second strength yarns 18 preferably does not degrade within the ground thereby increasing the service life of the geotextile 10.

With continued reference to FIGS. 1 and 3, the wicking yarns 22 may extend in at least one of the first direction 26 or the second direction 30. Specifically, the wicking yarns 22 may extend in the first direction 26, the second direction 30, or the wicking yarns 22 may include yarns extending in the first direction 26 as well as yarns extending in the second direction 30. In one exemplary aspect, as illustrated in FIG. 1, wicking yarns 22 extend in the second direction 30, and the wicking yarns 22 are arranged in between each of the second strength yarns 18 to form an alternating pattern with the second strength yarns 18. In yet other embodiments, the wicking yarns 22 may extend in a third direction different than either the first direction 26 or the second direction 30. The third direction can be oriented at an oblique angle relative to the first direction 26 or the second direction 30. For example, the third direction can be disposed at 30 degrees, 45 degrees, etc. relative to either the first direction 26 or the second direction 30.

Referring to FIGS. 1-3, the geotextile 10 comprises a knitted fabric. The knitting yarns 24 are disposed in a zigzag pattern, where the knitting yarns 24 are disposed diagonally or side to side along a length of the geotextile 10. The knitting yarns 24 can be disposed in the zigzag pattern in the first direction 26, the second direction 30, or both the first direction 26 and second direction 30. In the illustrated embodiment, the knitting yarns 24 are configured in a warp knit pattern to tie together and interconnect the strength yarns 14, 18 and the wicking yarns 22. In other embodiments, the knitting yarns 24 may be configured in other knitting patterns. The illustrated knitting yarns 24 may be made of the same or a different material than the material used to form the first strength yarns 14, the second strength yarns 18, or the wicking yarns 22. The knitting yarn material can include polymers, nylon, polyester, or polyolefin.

With reference to FIG. 1, the knit construction of the geotextile 10 allows the geotextile 10 to be formed with a plurality of layers, which are planar when the geotextile 10 is disposed on a flat surface. In the illustrated embodiment, the geotextile 10 includes a first layer 42 and a second layer 46 (see also FIG. 5). The first strength yarns 14 are arranged in the first layer 42, and the second strength yarns 18 are arranged in the second layer 46. The layers 42, 46 are discrete from one another. That is, the first strength yarns 14 do not cross over or under the second strength yarns 18 and into the second layer 46, and vice versa. In the illustrated embodiment, the wicking yarns 22 are arranged in the second layer 46 together with the second strength yarns 18. Like the second strength yarns 18, the illustrated wicking yarns 22 do not cross over or under the first strength yarns 14 and into the first layer 42. As such, the wicking yarns 22 extend linearly—rather than in a wave or undulating pattern—within the second layer 46. This minimizes the distance that liquid carried by the wicking yarns 22 must travel and thereby improves wicking performance of the geotextile 10 when compared to a woven geotextile. In other embodiments, the wicking yarns 22 may be arranged in the first layer 42, or both the first and second layers 42, 46. In some embodiments, the geotextile 10 may further include one or more additional layers 50 (FIG. 4), which may include strength yarns, wicking yarns, or yarns providing other functions (e.g., protective yarns to protect the strength yarns and wicking yarns from abrasion, etc.).

With reference to FIGS. 5-8, the wicking yarns 22 may have a variety of different cross-sectional shapes to promote active capillary movement of liquid along the lengths of the wicking yarns 22. The cross-sectional shapes may include a non-round shape, a non-rectangular shape, a non-circular shape, a non-oval shape, a non-flat shape, a lobular shape, an irregular shape, a multichannel shape, or a trilobal shape. In one example, the wicking yarns 22 includes a multichannel cross-sectional shape (FIG. 5). In another example, the wicking yarns 22 includes a trilobal cross sectional shape (FIG. 6). In another example, the wicking yarns 22 includes an irregular cross-sectional shape (FIG. 7). In another example, the wicking yarns 22 includes a lobular cross-sectional shape (FIG. 8). The cross-sectional shape of the wicking yarns 22 provides a large surface area to promote a large adhesion tension. Large adhesion tension increases the attraction between liquids and the wicking yarns 22. Increased attraction between liquids and the wicking yarns 22 increases the wicking capabilities of the geotextile 10 (e.g., to absorb and transport liquids faster).

The wicking yarns 22 are formed from a yarn material. The yarn material can be different than the material used to form the first strength yarns 14 and the second strength yarns 18. The yarn material can include nylon, polyester, or polyolefin. The yarn material includes liquid or moisture wicking properties. The yarn material can be hydrophilic, which allows for a large adhesion tension to attract water or other aqueous liquids. Large adhesion tension allows for an increased attraction between liquids and a surface of the wicking yarns 22 to increase the movement of liquid across the geotextile 10.

The geotextile 10 being formed as a knitted fabric provides advantages over non-knitted geotextiles used in roadway design. For example, the geotextile 10 formed as the knitted fabric provides beneficial positioning of the wicking yarns 22 in the geotextile 10. The wicking yarns 22 can be affixed and aligned in a single plane, multiple planes, the first direction 26 (i.e., machine direction), the second direction 30 (i.e., cross direction), both the first direction 26 and the second direction 30, and/or at angles less than ninety degrees relative to the first direction 26 and the second direction 30. As described above, the wicking yarns 22 are positioned in a linear in-plane fashion to wick moisture in the knitted fabric as compared to interlacing (over/under) in a woven fabric. Further, the geotextile 10 formed as the knitted fabric may better protect the wicking yarns 22 from compacted aggregate as compared to a non-knitted geotextile, since the wicking yarns 22 are arranged between strength yarns 18.

In one exemplary aspect, the geotextile 10 can be used for water and erosion control in roadways. For example, FIG. 9 illustrates an exemplary roadway 100 including a trafficked surface 104 (which in some embodiments may be a paved road surface, a path or sidewalk surface, or the like), one or more aggregate layers 108 (e.g., a layer of compacted crushed stone), and a subgrade soil layer 112. The geotextile 10 may be configured to enhance drainage of water or fluid between the trafficked surface 104 and the subgrade soil layer 112. For example, the geotextile 10 may be positioned between the subgrade soil layer 112 and the aggregate layer 108 and specifically may span a vertex 116 or high point of the subgrade soil layer 112. The wicking yarns 22, oriented in the second direction 30 or cross-direction in the illustrated embodiment, are configured to transport fluid in the second direction 30 toward the outer sides of the trafficked surface 104.

The geotextile 10 formed as the knitted fabric may transport moisture by capillary action across the geotextile 10 to change the moisture characteristics of adjacent soils. The geotextile 10 may provide functions of separation, filtration, and stabilization in roadway construction. The geotextile 10 may keep two incompatible materials (e.g., the aggregate layer 108 and subgrade soil layer 112) from intermixing over time. For example, the geotextile 10 may prevent the subgrade soil layer 112 from intruding into the aggregate layer 108 due to dynamic loading. The geotextile 10 may also protect the aggregate layer 108 from the intrusion of soil or fine materials. Fine materials, such as clay, may reduce friction within a layer of aggregate thereby causing stability issues and loss of support. The geotextile 10 may also reduce the pressure on subgrade soils 112 by modifying how the loads are distributed through the aggregate layer 108.

The geotextile 10 including the knitted fabric allows the moisture transportation to be customized depending on the application. For example, the wicking yarns 22 (i.e., capillary active yarn elements) may be placed adjacent the first strength yarns 14 or the second strength yarns 18 in the direction moisture needs to move. The moisture direction of the wicking yarns 22 can thus be customized in the first direction 26 and/or the second direction 30 depending on the application. For example, in roadway construction applications, the wicking yarns 22 can be orientated in the second direction 30 (e.g., cross direction) to provide improved moisture transportation away from the roadway.

The strength of geotextile 10 also can be customized in the first direction 26 and/or the second direction 30 such that the strength of geotextile 10 is balanced equally in all directions, or includes more or less strength in a particular direction (e.g., first direction 26 or second direction 30). The knitted configuration of the strength yarns 14, 18 may also allow the geotextile 10 to engage its full tensile strength more quickly (i.e. with minimal elongation) due to little to no slack in the strength yarns 14, 18 when compared to woven geotextiles, which may often elongate 4-5% before reaching their full tensile strengths. The knitted fabric of the geotextile 10 allows for reduced loss of tenacity compared to a woven geotextile, which may lose tenacity due to crimp effects.

Although the disclosure has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects of the disclosure as described.

Various features of the disclosure are set forth in the following claims.

Claims

1. A knitted geotextile comprising: a plurality of first strength yarns arranged in a first layer, each of the plurality of first strength yarns extending in a first direction;a plurality of second strength yarns arranged in a second layer, each of the plurality of second strength yarns extending in a second direction;a plurality of capillary active yarns arranged in at least one of the first layer or the second layer; anda plurality of knitting yarns interconnecting the plurality of first strength yarns, the plurality of second strength yarns, and the plurality of capillary active yarns.

2. The knitted geotextile of claim 1, wherein the plurality of knitting yarns is configured in a warp knit pattern.

3. The knitted geotextile of claim 1, wherein the first direction is a machine direction along which the knitted geotextile advances during manufacturing thereof, and wherein the second direction is a cross-direction perpendicular to the machine direction.

4. The knitted geotextile of claim 3, wherein each of the plurality of capillary active yarns extends in the second direction.

5. The knitted geotextile of claim 3, wherein each of the plurality of capillary active yarns extends in the first direction.

6. The knitted geotextile of claim 1, wherein each of the plurality of capillary active yarns is made of nylon.

7. The knitted geotextile of claim 1, wherein each of the plurality of first strength yarns is made of polypropylene.

8. The knitted geotextile of claim 7, wherein each of the plurality of second strength yarns is made of polypropylene.

9. The knitted geotextile of claim 1, wherein the knitted geotextile has a tensile strength of at least 10 kN/m under ASTM D4595.

10. The knitted geotextile of claim 1, wherein each of the plurality of capillary active yarns is arranged in the second layer, and wherein the plurality of capillary active yarns and the plurality of second strength yarns are arranged in an alternating pattern in the second layer.

11. A knitted geotextile comprising: a plurality strength yarns;a plurality of capillary active yarns configured to transport fluid in at least one of a first direction or a second direction; anda plurality of knitting yarns interconnecting the plurality of strength yarns and the plurality of capillary active yarns in a warp knit configuration,wherein the first direction is a machine direction along which the knitted geotextile advances during manufacturing thereof, and wherein the second direction is a cross-direction perpendicular to the machine direction.

12. The knitted geotextile of claim 11, wherein each of the plurality of capillary active yarns extends in the second direction.

13. The knitted geotextile of claim 11, wherein each of the plurality of capillary active yarns extends in the first direction.

14. The knitted geotextile of claim 11, wherein each of the plurality of capillary active yarns is made of nylon.

15. The knitted geotextile of claim 11, wherein each of the plurality of strength yarns is made of polypropylene.

16. The knitted geotextile of claim 11, wherein the knitted geotextile has a tensile strength of at least 10 kN/m under ASTM D4595.

17. The knitted geotextile of claim 11, wherein the plurality of capillary active yarns and the plurality of strength yarns are arranged in an alternating pattern.

18. A knitted geotextile configured to enhance drainage of fluid between a trafficked surface and a subgrade soil, the knitted geotextile comprising: a plurality of capillary active yarns configured to transport fluid in at least one of a first direction or a second direction; anda plurality of knitting yarns interconnecting the plurality of capillary active yarns in a warp knit configuration.

19. The knitted geotextile of claim 18, wherein the plurality of capillary active yarns is positioned at a vertex of the subgrade soil.

20. The knitted geotextile of claim 18, wherein the first direction is a machine direction along which the knitted geotextile advances during manufacturing thereof, and wherein the second direction is a cross-direction perpendicular to the machine direction.