WO2024180422A1

WO2024180422A1 - Reinforcing composite material

Info

Publication number: WO2024180422A1
Application number: PCT/IB2024/051599
Authority: WO
Inventors: Nicola BRUSA
Original assignee: Hyper Fibers S.R.L.
Priority date: 2023-02-27
Filing date: 2024-02-20
Publication date: 2024-09-06
Also published as: IT202300003417A1

Abstract

Reinforcing composite material (100) comprising a first sheet (10) made of flexible material, a second sheet (20) made of flexible material and a plurality of reinforcing composite strips (1) interposed between said first sheet (10) and said second sheet (20). Each reinforcing composite strip (1) comprises: - a covering capsule (2) surrounding a plurality of longitudinal channels (3) developing parallel to a longitudinal development direction (X) of the reinforcing composite strip (1) and arranged in sequence between opposite side ends (1a) of the reinforcing composite strip (1), and - a plurality of longitudinal reinforcing fibres (3 a) arranged within the longitudinal channels (3). The reinforcing composite strips (1) are coupled to the first sheet (10) at respective lower surfaces (2b) of the covering capsules (2) and to the second sheet (20) at respective upper surfaces (2a) of the covering capsules (2), so that the respective longitudinal development directions (X) are parallel. The reinforcing composite material (100) does not comprise any further reinforcing composite strip developing along respective longitudinal development direction perpendicular to the longitudinal development direction (X) of the composite reinforcing strip (1).

Description

DESCRIPTION

“REINFORCING COMPOSITE MATERIAL”

The present invention relates to a reinforcing composite material.

In particular, the present invention relates to a reinforcing composite material for the construction, civil, environmental, hydraulic, geotechnical and mining engineering sectors, and more generally for all those applications where efficient soil reinforcement/containment is required.

The reinforcing composite material referred to here is a flexible ribbon-like material in strip form, i.e. it has a much smaller thickness with respect to the other two dimensions.

Typically, reinforcing composite materials used in the construction industry are defined by the use of reinforcing strips, i.e. reinforcing composite products in the form of a strip (also known as “strap” or “tape” or “geo-strip”) generally obtained by co-extruding a coating capsule containing a core of fibres, filaments, wires or inserts with tensile strength properties.

Using high-tenacity wires, yarns and fibres, it is in fact possible to obtain reinforcing strips that offer the necessary support and resistance to loads and greater durability than ordinary structural construction methods and materials such as steel and concrete.

The strips are then typically combined in warp and weft to create meshes or grids (also known as “geogrids”) and are then inserted into the ground to reinforce it and thus create retaining walls or embankments reinforced both internally and at the base.

The Applicant has noted, however, that geogrids of the known type have certain limitations that in some cases discourage or even prevent their use for certain types of applications.

In particular, strips of the known type, always and only being combined to form a grid, can provide tensile strength in both directions (warp and weft); however, for applications such as the creation of retaining walls or escarpment stabilisation, geogrids are typically required to provide strength in a preferential direction (typically the warp, as opposed to the laying direction). Indeed, in the stabilisation of embankments, escarpments, walls or slopes, the fact of having tensile strength in both directions is not strictly necessary; on the contrary, the provision of two directions of resistance, in addition to defining an overdesigned or overengineered solution, could limit the tensional response in the required direction.

In design engineering and standards, one main direction of load and force distribution is typically considered, and therefore one direction of tensile strength may be sufficient and guarantee the stability of the structure in both the short and long term.

Therefore, although the grid design allows the reinforcement to be laid precisely (as opposed to individual strips that would have to be laid one by one), these geogrids are unnecessarily expensive, redundant and heavy to handle.

The Applicant has also noted that it is disadvantageous that geogrids alone are not capable of performing other functions outside of structural reinforcement, so they are often combined with a sheet of material with a different function.

Once laid in place, however, tension, loosening or slippage between the strips and the sheet often occurs so that the soil is not properly stabilised/contained. The risk of compromising the entire structural reinforcement in such cases is very high.

In this context, the technical task at the basis of the present invention is to propose a reinforcing composite material that overcomes one or more of the drawbacks of the prior art mentioned above, providing a solution that is simple and inexpensive to produce, that is effective, efficient, convenient and reliable in use, and that is capable of simplifying reinforcement operations.

The defined technical task and the specified aims are substantially achieved by a reinforcing composite material, comprising the technical characteristics set forth in one or more of the appended claims.

In particular, the present invention provides a reinforcing composite material comprising a first sheet of flexible material, a second sheet of flexible material and a plurality of reinforcing composite strips interposed between the first sheet and the second sheet.

Each reinforcing composite strip comprises: - a covering capsule surrounding a plurality of longitudinal channels developing parallel to a longitudinal development direction of the reinforcing composite strip and arranged in sequence between opposite side ends of the reinforcing composite strip, and

- a plurality of longitudinal reinforcing fibres arranged inside reinforcing channels of the plurality of longitudinal channels.

The reinforcing composite strips are advantageously coupled to the first sheet at respective lower surfaces of the covering capsules and to the second sheet at respective upper surfaces of the covering capsules, so that the respective longitudinal development directions are parallel.

The reinforcing composite material does not comprise any further reinforcing composite strip developing along respective longitudinal development direction perpendicular to the longitudinal development direction of the composite reinforcing strip.

In other words, all the reinforcing composite strips are arranged parallel to each other so as to not cross each other, hence the parallel strips are adjacent to each other so as no contact occurs among them.

Thus, the reinforcing composite material of the present invention do not comprise any grid, as only parallel longitudinal reinforcing composite strips are present, said reinforcing composite strips being not linked by any transverse or perpendicular strip.

The reinforcing composite material according to the invention, thus having strips arranged in weft only or warp only, is able to provide the required strength in the orientation required by the design, with less superfluous mass than known grids and therefore less material to be handled on site, while at the same time guaranteeing precise positioning of the strips as they are coupled to the sheets, and proper functioning of the composite material once installed.

The reinforcing strips are made integral to the sheets and therefore held advantageously in place by them, thus preventing any relative movement between the strips and the sheets.

The orientation of the strips defined in the design advantageously determines the reinforcement direction, also eliminating waste due to site work. The composite material can therefore also be placed parallel to the structure and not perpendicularly as is the case with geogrids or geostrips of the prior art.

Obviously, single sheets laid separately, without coupling to the strips, would have entailed double coupling processes in situ and in any case could have generated a layer of discontinuity between the two sheets, whereas the invention advantageously presents a pre-packaged “sandwich structure”, whereby the reinforcing composite material is already “ready to use” to be laid and put in place for efficient structural reinforcement.

The reinforcing composite material of the present invention facilitates laying operations and reduces laying time as it is already pre-coupled and ready to use for efficient performance.

Advantageously, the reinforcing composite material can also be made in tape form and supplied in roll form to simplify transport and laying operations.

The dependent claims herein incorporated for reference, correspond to different embodiments of the invention.

Further characteristics and advantages of the present invention will appear more clearly from the indicative, and therefore non-limiting, description of a preferred but not exclusive embodiment of a reinforcing composite material, as illustrated in the appended drawings.

Figure 1 is a schematic perspective view of a reinforcing strip forming part of the reinforcing composite material covered by the present invention.

Figure 2 is a schematic section of a reinforcing composite material according to the present invention, while Figures 2A and 2B are two enlargements of the respective sheets.

Figures 3 and 4 are schematic perspective views of rolls comprising a reinforcing composite material tape in accordance with two alternative embodiments of the present invention.

With reference to the appended figures, a reinforcing composite material is indicated overall as 100.

The reinforcing composite material 100 according to the present invention advantageously comprises a first sheet 10 made of flexible material, a second sheet 20 made of flexible material and a plurality of reinforcing composite strips 1 interposed between the first sheet 10 and the second sheet 20.

The reinforcing composite material 100 referred to herein is therefore a multilayer material in the form of a sheet with a certain thickness, commonly referred to as a “geo-cover” or “geo-membrane” or “geo-mat”, and is suitable to be placed in contact with the soil, even in immersed conditions, to reinforce, contain and stabilise it.

With reference to Figure 1, it should be noted that the term “strip” is intended to denote a substantially flat ribbon-like element having a length, measured along a longitudinal development direction X of the strip 1, which is greater than the width of the strip 1, measured perpendicularly to the longitudinal development direction X, and having a width which is much greater than the thickness of the strip 1, the latter being measured perpendicularly to the longitudinal development direction X and the width of the strip 1.

Preferably the strip 1 has a width comprised between 10 and 200 mm, even more preferably equal to 85 mm.

The strip 1 has two opposite side ends la with respect to the longitudinal development direction X and two opposite terminal ends lb, developing perpendicular to the longitudinal development direction X. In other words, the length of the strip 1 is measurable between the terminal ends lb, while the width is measurable between the side ends la.

The strip 1 comprises a coating capsule 2, e.g. a polymer matrix (e.g. LLPDE), surrounding a plurality of longitudinal channels 3 running parallel to the longitudinal direction X of the reinforcing strip 1 and arranged in sequence between the opposite side ends la.

In other words, the longitudinal channels 3 are arranged parallel adjacent to one other in sequence within the strip 1 and extend along the entire length A of the strip 1.

The strip 1 advantageously comprises a plurality of longitudinal reinforcing fibres 3 a arranged within the longitudinal channels 3. In particular, a “plurality of longitudinal reinforcing fibres” 3a means a yam or filament made from a plurality of fibres, strands, filaments or inserts, with tensile strength characteristics and joined together longitudinally to define a longitudinally developed reinforcing element.

Preferably, the longitudinal reinforcing fibres 3a are made of synthetic or polymeric or bio-polymeric or natural or plant-based materials. Inserts of ferrous or metallic origin can also be provided.

Note therefore that the term “longitudinal” is intended to indicate that the plurality of fibres defines a yam developing in a direction parallel to the longitudinal development direction X of the strip 1.

According to a possible embodiment, not illustrated, the plurality of fibres can also be defined by yarns or threads formed from mixed stmctures or combined to form a hybrid yarn/structure (capable of increasing the final performance of the strip itself).

Preferably each channel 3 has a width value, measured perpendicular to the longitudinal development direction X of the reinforcing strip 1 and parallel to the width of the reinforcing strip 1, comprised between 0.5 mm and 100 mm, even more preferably comprised between 2 mm and 10 mm.

Preferably the channel 3 has a thickness value, measured perpendicular to the longitudinal development direction X of the reinforcing strip 1 and parallel to the thickness of the reinforcing strip 1, comprised between 0.1 mm and 20 mm, even more preferably comprised between 1 mm and 5 mm.

Preferably the distance between consecutive longitudinal channels 3 is smaller than the width of the longitudinal channels 3.

The coating capsule 2 has an upper surface 2a and an opposite lower surface 2b. Advantageously the reinforcing composite strips 1 are coupled to the first sheet 10 at respective lower surfaces 2b of the covering capsules 2 and coupled to the second sheet 20 at respective upper surfaces 2a of the covering capsules 2, so that the respective longitudinal development directions X are parallel.

The present invention therefore proposes a reinforcing composite material wherein the strips are sandwiched between the two sheets 10, 20 of flexible material, advantageously allowing different types of sheets to be applied to perform different functions: in fact, the strips 1 give the reinforcing characteristic to the material 100, while the sheets 10, 20 can be selected to perform different functions (preferably at least two different functions).

The sheets 10, 20 may have one or more of the following functional characteristics: filtration, separation, drainage, anti-erosion, containment, waterproofing.

Depending on the functional type of material of which the sheet 10, 20 is made, it can be defined as: geotextile (preferably PP with needle-punched threads), geomat (preferably with 3D structure), geo-membrane (preferably PE), geo-drain or geo-cover (also geo-cement, GCCMs).

The lamination of the strips 1 to the sheets 10, 20 can be carried out according to one or more of the following production techniques: knitting, interweaving, bonding, stitching, interlocking, welding, glueing, heating, sewing, spraying.

In any case, the term “coupled” means that the strips 1 are made integral and irreversibly connected to the sheets 10, 20, i.e. they completely adhere to the sheets 20, 20 at the respective upper surfaces 2a and lower surfaces 2b (thus there are no overlaps as in the case of grids).

Advantageously, the present invention does not require additional reinforcing strips arranged perpendicularly to the parallel strips 1, making the composite material 100 easy to manufacture and also speeding up its production.

According to a possible embodiment, preferably the first sheet 10 and/or the second sheet 20 made of flexible material comprise a 3D structure of thread-like elements 11, 21 defining between them a plurality of cavities 12, 22 suitable, in use, to be at least partially interpenetrated with the ground.

In other words, the cavities 12, 22 interposed between the thread-like elements 11, 21, in particular the more superficial cavities 12, 22 defining the outer surface of the sheet 10, 20, when the material 100 is installed and then laid in contact with the soil, are configured to receive small portions of soil (depending on the particle size of the soil, it is possible to size the optimal conformation of the cavities 12, 22) thus increasing the friction with the soil, so as to improve the adherence between the two elements and prevent them from slipping/loosening during the cycle of use.

The sheet 10, 20 thus created in other words is substantially defined by rough outer surfaces suitable to be placed, in use, frictionally in contact with the ground. The cavities 12, 22 are in fact open to the outside of the sheet 10, 20 to interface and be interpenetrated by the ground creating friction.

The 3D structure of the thread-like elements 11, 21 (“thread-like elements” is intended to mean threads, fibres or filaments) can be twisted, knotted or tangled in a regular or random/irregular manner.

The sheet 10, 20 made of flexible material can thus be defined as a so-called “cover”, i.e. a three-dimensional structure of thread-like elements 11, 21 having a prevailing development dimension with respect to the others (i.e. a sheet) and presenting rough outer surfaces (i.e. rough, i.e. not smooth to the touch, or irregular, i.e. presenting ripples, or jagged, i.e. presenting a succession of irregular / non-homogeneous projections and indentations defined by the outlines of the threads themselves and/or by a tangle of the threads themselves). The rough outer surfaces thus advantageously increase the surface friction of the reinforcing composite material. The surfaces of the cover when in contact with the ground are therefore frictional surfaces that improve the characteristics of adherence to the ground, preventing slipping and loosening when in place. The resulting reinforcing composite material 100 can advantageously be described as having “improved adhesion”.

The reinforcing composite material 100 can therefore be advantageously used to prevent erosion phenomena and planar surface subsidence of escarpments or retaining walls.

According to a first possible embodiment of the sheet 10, 20 employable for making the material 100 according to the present invention, the 3D structure of thread-like elements is made (with reference to the enlargement of Figure 2A relating to the second sheet 20) preferably of entangled synthetic filaments 21, for example made of polypropylene, even more preferably made by spraying or extrusion or additive manufacturing. Between the entangled synthetic filaments 21 the cavities 22 are defined.

An example of such a sheet is the so-called “geo-mat”, i.e. a three-dimensional structure of highly deformable polypropylene monofilaments with high porosity (normally around 90% or even more). Geo-mats are long-term solutions, capable of handling erosion control problems in both dry and wet environments. They can protect a slope from erosion caused by the flow of water from rainfall, streams or rivers.

In accordance with a second possible embodiment of the sheet 10 employable for making the material 100 according to the present invention, the 3D structure of thread-like elements is made (with reference to the enlargement of Figure 2B relating to the first 10) preferably with a layer of textile material 11 presenting a plurality of rings I la of protruding filaments defining the plurality of cavities 12 between them.

In particular, the rings I la may be defined by filaments drawn from the layer of textile material 11 (obtained according to known drawing techniques) or they may be made from additional filaments interlaced with the textile structure to define loops, flounces or bridging threads. In addition, any further filaments can be made of non-textile material.

In other words, the sheet 10 has a base layer with interwoven filaments (i.e. the layer of textile material 11) and a number of through rings I la protruding from the base layer that define the cavities 12 between them, creating a rough surface that generates friction with the ground and improves the adhesion of the reinforcing system.

The sheets 10, 20 illustrated in Figure 2 are just a few examples, however, combinations of sheets 10, 20 with different functional characteristics can be envisaged depending on design requirements.

Preferably, in accordance with an embodiment not illustrated in the appended figures, it is possible for the reinforcing strips 1 to be at least partially embedded in this sheet 10, 20. For example, it is possible to make the sheet 20 by spraying synthetic filaments 21 directly onto the strips 1 arranged in parallel and embedding them at least partially to make a layer of entangled synthetic filaments 21 comprising a plurality of cavities 22 and within which the strips 1 are trapped. Preferably the material 100 has an overall thickness, measured perpendicular to the longitudinal development direction X of the reinforcing composite strip 1, comprised between 0.5 mm and 40 mm, even more preferably between 5 mm and 10 mm.

Preferably, the reinforcing composite material 100 can be made in rolls in order to optimise transport space and facilitate laying operations.

With reference to Figure 3, according to a further aspect of the present invention there is a roll A comprising a reinforcing composite strip 100 wound around a winding and unwinding axis R so that the winding and unwinding direction D of the strip is parallel to the longitudinal development directions X of the reinforcing composite strips 1 (note that the sheet 20 has been omitted for illustrative simplicity).

Furthermore, with reference to Figure 4, according to a further aspect of the present invention there is a roll A comprising a reinforcing composite strip 100 wound around a winding and unwinding axis R so that the winding and unwinding direction D of the strip 100 is perpendicular to the longitudinal development directions X of the reinforcing composite strips 1 (note that the sheet 20 has been omitted for illustrative simplicity).

Advantageously, the fact that the roll A can be unrolled with unrolling direction D parallel to a wall and that the strips are therefore arranged perpendicular to the wall (in the correct tensile tension direction) allows the material 100 to be laid quickly over any length without the need for intermediate cuts, improving the laying efficiency by appropriately dimensioning the width of the roll according to design requirements.

The present invention achieves the proposed aims by overcoming the drawbacks complained of in the prior art and by providing an efficient, high-performance reinforcing composite material capable of improving laying conditions and durability while optimising costs.

Claims

1. Reinforcing composite material (100) comprising a first sheet (10) made of flexible material, a second sheet (20) made of flexible material and a plurality of reinforcing composite strips (1) interposed between said first sheet (10) and said second sheet (20); wherein each reinforcing composite strip (1) comprises:

- a covering capsule (2) surrounding a plurality of longitudinal channels (3) developing parallel to a longitudinal development direction (X) of the composite reinforcing strip (1) and arranged in sequence between opposite side ends (la) of said composite reinforcing strip (1), and

- a plurality of longitudinal reinforcing fibres (3 a) arranged within the longitudinal channels (3); said reinforcing composite strips (1) being coupled to said first sheet (10) at respective lower surfaces (2b) of the covering capsules (2) and to said second sheet (20) at respective upper surfaces (2a) of the covering capsules (2), so that the respective longitudinal development directions (X) are parallel; wherein said reinforcing composite material (100) does not comprise any further reinforcing composite strip developing along respective longitudinal development direction perpendicular to said longitudinal development direction (X) of the composite reinforcing strip (1).

2. Reinforcing composite material (100) according to claim 1, wherein said first sheet (10) made of flexible material and/or said second sheet (20) made of flexible material comprise a 3D structure of thread-like elements defining between them a plurality of cavities (12, 22) suitable, in use, to be at least partially interpenetrated with the ground.

3. Reinforcing composite material (100) according to claim 2, wherein said 3D structure of thread-like elements is made of tangled synthetic filaments (21), for example polypropylene, preferably made by spraying or extrusion or additive manufacturing.

4. Reinforcing composite material (100) according to claim 2, wherein said reinforcing strips (1) are at least partially embedded in said sheet (10, 20).

5. Reinforcing composite material (100) according to claim 2, wherein said 3D structure of thread-like elements is made with a layer of textile material (11) having a plurality of filament protruding rings (I la) defining said plurality of cavities (12) with each other, said protruding rings (I la) being filaments drawn from said layer of textile material (11) or being made with further filaments interwoven with the layer of textile material (11).

6. Reinforcing composite material (100) according to claim 1, wherein said reinforcing composite material (100) has an overall thickness, measured perpendicularly to the direction of longitudinal development (X) of the reinforcing composite strip (1), comprised between 0.5 mm and 40 mm, even more preferably between 5 mm and 10 mm.

7. Roll (A) comprising a tape of reinforcing composite material (100) according to one or more of the preceding claims, said tape being wound around a winding and unwinding axis (R) so that the winding and unwinding direction (D) of the tape is parallel to the longitudinal development directions (X) of the reinforcing composite strips (1).

8. Roll (A) comprising a tape of reinforcing composite material (100) according to one or more of the preceding claims, said tape being wound around a winding and unwinding axis (R) so that the winding and unwinding direction (D) of the tape is perpendicular to the longitudinal development directions (X) of the reinforcing composite strips (1).