WO2023126232A1

WO2023126232A1 - Construction reinforcement with meltable substrate

Info

Publication number: WO2023126232A1
Application number: PCT/EP2022/086631
Authority: WO
Inventors: Gerhard Vitt; Tanika DEGRANDE; Henk CORNELUS
Original assignee: Nv Bekaert Sa
Priority date: 2022-01-03
Filing date: 2022-12-19
Publication date: 2023-07-06

Abstract

A structure for the reinforcement of pavements, said structure having a longitudinal direction and a transverse direction, said structure comprising a first group of reinforcement element, said reinforcement elements of said first group being oriented in a first direction in a mutual parallel or mutual substantially parallel position, said reinforcement elements being integrated in a substrate, whereby said substrate comprises or consists of a non-metal material with a melting temperature between 60 and 135 °C.

Description

Title: CONSTRUCTION REINFORCEMENT WITH MELTABLE SUBSTRATE

Description

Technical Field

[0001 ] The invention relates to a structure adapted for the reinforcement of constructions such as roads or pavements, and more particularly for the reinforcement of asphalt roads or pavements. The invention also relates to a method manufacturing such structure and a method of installing such structure for renovating an existing road or pavement.

Background Art

[0002] W0-A1 -2014/161930 discloses a fabric for reinforcing roads or pavements. The fabric has assemblies of grouped metal filaments that are coupled to or integrated in a carrier.

[0003] WO-A1-2014/161931 discloses an alternative of such a fabric. This fabric comprises assemblies of grouped metal filaments that are held in a parallel position.

[0004] W0-A1 -2016/062458 discloses yet another alternative of such a fabric. This fabric is provided with reinforcement elements with weakened zones or spots in order to facilitate the later breaking up of the pavement and to allow easier recycling of the reinforcing elements.

[0005] The above-mentioned prior art fabrics are anti-reflective cracking (ARC) interlayer fabrics, e.g. metal or steel-based anti-reflective cracking interlayer fabrics that fit very well for asphalt road renovation. These fabrics allow a fast and relatively easy renovation of the road at a rather low cost, since the existing pavement is used as base. This already existing pavement has joints or cracks that might get reflected in the asphalt overlayer or top layer after renovation. To delay this reflection as long as possible, an ARC interlayer fabric is added before applying the asphalt.

[0006] Similar to pavements and roads without an ARC interlayer fabric, adhesion both downwards to the existing pavement or road and upwards to the new asphalt overlayer is crucial for the performance and lifetime of the road or pavement renovation. This is the reason why a so-called tack coat or bitumen layer is first laid down on the existing pavement or road and the fabric is then rolled out and pushed a little bit into the tack coat or bitumen layer.

[0007] Experience, however, has shown that, despite the proper use of tack coats, adhesion between the new and the existing layers may be lower when an ARC interlayer fabric is used than between the same layers when no ARC interlayer fabric is used r.

[0008] US 2014/0170916 A1 discloses a non-woven cementitious composite for reinforcement of pavements or roads. This non-woven composite comprises several layers, amongst others an impermeable layer that may have reinforcements and a structure layer. The impermeable layer may extend laterally outward the structure layer.

Disclosure of Invention

[0009] It is a general object of the present invention to overcome the problems of the prior art.

[0010] It is a particular object of the present invention to improve the adhesion of a reinforcement structure when reinforcing a road or pavement, especially to improve the adhesion to a new road or pavement layer and/or to improve the adhesion of two road or pavement layers, especially over the adhesion of two road or pavement layers separated by an ARC interlayer fabric.

[0011 ] Viewed from another aspect of the invention, it is also an object to improve the stress distribution, the ease of installation as well as the ease of recycling of structures according to the invention.

[0012] According to a first aspect of the invention, there is provided a structure for the reinforcement of pavements, said structure having a longitudinal direction and a transverse direction, said structure comprising a first group of reinforcement elements oriented in a first direction in a mutual parallel or mutual substantially parallel position, said reinforcement elements being integrated in a substrate , whereby said substrate comprises or consists of a non-metal material with a melting temperature between 60 and 135 °C. According to the invention, the substrate may comprise or consist of a non-metal material with a melting temperature for example between 75 and 145 °C, preferably between 95 and 135 °C, further preferred between 100 and 130 °C. Melting temperature may thereby be determined for example by dynamic scanning calorimetry (DSC) according to ISO 11357-3.

[0013] A melting temperature of a non-metal material according to the invention may thereby contribute to the fact that the substrate melts and/or dissolves when asphalt or bitumen or any other bitumen based material, preferably with a temperature similar to or higher than the melting temperature, is applied during installation, preferably the molten and/or dissolved substrate may thereby possibly for example mix with the asphalt or bitumen or any other bitumen based material. This means that while the substrate is present during installation, the substrate melts and/or dissolves once asphalt or bitumen or any other bitumen based material is applied and is thus no longer present as a substrate during the subsequent lifetime of the structure. However, according to the present invention, the substrate is not burnt or molten away, especially in a separate step, but rather melts and/or dissolves once asphalt or bitumen or any other bitumen based material is applied. This contributes to achieving a batter adhesion between new and existing layers of road and pavements, also when an ARC interlayer is used. This also contributes to the fact that when an asphalt layer or bitumen layer or layer of any other bitumen based material applied on a structure gets recycled there is no need to separate the substrate from other components as the substrate has molten and/or preferably, the molten substrate may have mixed with the asphalt or bitumen or any other bitumen based material. This may contribute to make recycling reinforced roads and pavements much easier and thus contribute to improve sustainability.

[0014] In an embodiment of the invention, the substrate consists of a non-metal material with a melt mass-flow rate (MFR) at 160 °C and 2.16 kg of between 5 and 600 g/10 min, preferably between 7 and 500 g/10 min preferably between 20 and 250 g/10 min, further preferred between 25 and 65 g/10 min or between 90 and 175 g/10 min. The MFR may thereby for example be determined for example according to ISO 1133 or ASTM D1238. This may contribute to improve the compatibility or mixing of the molten substrate with asphalt or bitumen or any other bitumen based material.

[0015] The structure has a width in a transverse direction. The structure comprises a substrate and further comprises discrete and spaced apart reinforcement elements extending within the structure width and being fixed or bound to the substrate. The substrate has a substrate width that is equal or smaller than the width of the structure. If the substrate width is smaller, the reinforcement elements may protrude out of the substrate. It is hereby understood that the structure may also comprise other reinforcing elements, e.g. longitudinal, transverse or obliquely arranged reinforcement elements, which do or do not protrude or extend out of the structure. In case, where the reinforcement elements protrude from the substrate, two structures may be placed next to each other with overlapping reinforcement elements but without overlapping substrate layers. This may help to further improve adhesion, especially over solution where multiple layers of substrate may overlap.

[0016] As mentioned, the reinforcement elements are discrete and spaced apart. The distance between two neighbouring reinforcement elements ranges from 5 mm to 90 mm, e.g. from 10 mm to 80 mm, e.g. from 20 mm to 70 mm. [0017] The advantage of the invention can be explained as follows. In most cases the substrate contributes to an easy installation of the structure and/or improved dimensional stability and/or improves the adhesion of the structure during installation, so as to give for example the possibility to drive over it. Moreover, the present invention may further improve adhesion thorough the lifetime by limiting interfaces of mismatching materials that may contribute to related problems. In addition, the invention may facilitate the recycling of the structure or of an asphalt or bitumen or any other bitumen-based material layer, because a molten and/or dissolved substrate doesn’t need to be separated from the asphalt or bitumen or any other bitumen-based material and/or other components of the structure for reuse.

[0018] The substrate may for example be a non-woven, woven or knitted substrate or film or a grid. The substrate may preferably for example comprise or consist of a non-metal material. The substrate may thereby comprise openings of any form or shape, especially for example polygonal, rectangular or square openings or perforations or embossing and/or comprise struts and ties, particularly when the substrate may be a grid. The substrate may also comprise round or oval openings or perforations. The openings or perforations in the substrate may all have the same size or may have different sizes. The parts of the grids or the substrate as well as the corresponding openings or perforations of the grids or the substrate may be aligned respectively with the reinforcing elements and the openings between these. Alternatively, the parts of the grids or the substrate as well as the corresponding openings or perforations of the grids or the substrate may not be aligned respectively with the reinforcing elements and the openings between these, so that the reinforcing elements may extend over openings or perforations in the grid or substrate. This may allow for easy installation and/or dimensional stability while also contributing to reduce the amount of substrate used. The amount of substrate per m² may thereby preferably be for example between 10 and 150 g/m², preferably between 20 and 120 g/m², further preferred between 30 and 90 g/m², further preferred between 40 and 80 g/m². In an embodiment of the invention, the non-metal material may for example selected from the group comprising: polylactic acid (PLA) or polylactic acid copolymers, ethylene-vinyl acetate copolymers (EVA), polypropylene or polypropylene copolymers, polyesters, co-polyesters, polyamids, co-polyamids, thermoplastic polyurethanes. In an embodiment of the invention, the non-metal material may for example preferably selected from the group comprising: polylactic acid (PLA) or polylactic acid copolymers, ethylene-vinyl acetate copolymers (EVA), polyesters, copolyesters, polyamids, co-polyamids, thermoplastic polyurethanes. These latest materials are thereby particularly preferred as despite having a similar melting temperature, they have a particular melting behavior, especially for example compared to polyethylene that further improves adhesion between old and new layers of road and pavements, also when an ARC interlayer is used. In an embodiment, a structure according to the invention may comprise one or more layers of substrate, preferably exactly one layer of substrate. In an embodiment, two or more layers of substrate may each be different from each other, especially be different regarding its nature and/or its properties and/or the material used.

[0019] The substrate may be spunbond, needle-punched, spunlaced, woven, punched out, extruded, expanded or thermobonded. The substrate may also be perforated or micro-perforated. The substrate may thereby contribute to give the structure dimensional stability, especially during installation. This may especially for example help to improve ease of installation, since curling and/or waviness of the structure may be reduced thanks to the substrate, especially during installation. A non-woven substrate or a grid may further help a tack coat, which is applied as first layer above the road to be renovated, to penetrate in the substrate and to ensure a good adhesion during installation.

[0020] The main function of the substrate is to facilitate installation. The substrate especially keeps the discrete and spaced apart reinforcement elements parallel during handling, storage, transport and installation. The substrate, as such, may preferably not provide reinforcement.

[0021 ] That the reinforcement elements extend over the width of the structure does not necessarily mean that the reinforcement elements are oriented perpendicular to the longitudinal direction of the structure. They may also be obliquely oriented.

[0022] The reinforcing elements may be or comprise a material with a melting temperature > 165 °C, preferably between 170 °C to 2000°C. This will allow reinforcing elements to not be affected by the application of asphalt or bitumen or bitumen based materials, preferably for example with a temperature of about 180 °C. In an embodiment reinforcing elements may be or comprise metal wires, bundles of metal wires or metal cords, carbon fibers, synthetic fibers, basalt fibers, glass fibers or yams made therefrom, extruded reinforcement elements or the like, especially for example steel cords. Preference is given to steel cords since steel cords both have a high strength and flexibility due to its twisting of thin steel wires or steel filaments. The steel cords may be provided with weakened zones, e.g. in the form of brittle spots located along the length of the steel cords with distances between subsequent spots ranging from 10 cm to 100 cm. The weakened zones may be realized by welding. Another form of weakening may be to apply a series of indentations.

[0023] The reinforcement elements may be fixed or bound in various ways, e.g. by means of a glue or by means of a yarn.

[0024] Although the reinforcement elements may protrude at both sides, in a preferred embodiment of the first aspect of the invention, the transversal reinforcement elements protrude at only one longitudinal side of the structure.

[0025] Preferably the reinforcement elements may be transversal reinforcement elements and/or the transversal reinforcement elements protrude out of the substrate over a protrusion width ranging from 40 mm to 450 mm, e.g. from 50 mm to 300 mm, e.g. from 50 mm to 200 mm. The protrusion width is measured here along a line perpendicular to the longitudinal direction of the structure.

[0026] The width of the structures may range for example from 1 .0 m to 4.0 m, e.g. from 1 .0 m to 3.0 m, e.g. from 1 .0 m to 2.5 m.

[0027] As already mentioned, preferable embodiments of the reinforcement elements are steel cords. Most preferably, those steel cords do not flare at their ends, particularly not at the ends which protrude out of the substrate. Preferably the ends of the steel cord are therefore welded together.

[0028] In order to facilitate transport, the invention structure may preferably be wound in a roll. This is made possible, amongst others, by the flexible nature of the reinforcement elements.

[0029] In an embodiment of the invention, the included angle between said first direction and said longitudinal direction may be ranging for example between -80° and + 80°. In an embodiment of the invention, said first direction may be oriented in the longitudinal direction of said structure.

[0030] In an embodiment of the invention, the reinforcing elements are integrated in said substrate by at least one yam. Integrated in a substrate in the sense of the invention may thereby also mean coupled or attached, preferably with stiches, to a substrate. In an embodiment of the invention, the structure comprises a second group of reinforcing elements, said reinforcing elements of said second group being oriented in a second direction, said second direction being different from said first direction, preferably perpendicular to the first direction.

[0031 ] In an embodiment of the invention, the structure may further comprise a asphalt overlay or bitumen overlay or overlay of any other bitumen based material or overlay of chipping/small stones applied over said structure for the reinforcement of pavements.

[0032] In an embodiment of the invention, the structure may further comprise an interlayer, such as for example chipping/small stones and/or a chalk emulsion and/or a stress-absorbing membrane interlayer (SAMI), between said pavement and said structure for the reinforcement of pavements and/or between said structure for the reinforcement of pavements and said bitumen overlay.

[0033] According to another aspect of the invention, there is provided method of to manufacture a structure as defined in any one of claims 1 to 10, said method comprising the steps of providing at least a first group of reinforcement elements, providing non-metal substrate with a melting temperature between 60 and 135 °C; coupling said reinforcing elements of said first group to said substrate so that said reinforcing elements are oriented in a first direction in a mutual parallel or mutual substantially parallel position.

[0034] In an embodiment of the invention, said method may comprise the steps of

- providing at least a first group of reinforcing elements,

- integrating said reinforcing elements in a substrate comprising non-metal material with a melting temperature between 60 and 135 °C.

[0035] A method of installing a structure for the reinforcement of pavements, said method comprising the steps of

- positioning a reinforcement structure of pavements on a pavement surface; said structure having a longitudinal direction and a transverse direction, said structure comprising a first group of reinforcing elements, said reinforcing elements of said first group being oriented in a first direction in a mutual parallel or mutual substantially parallel position, said reinforcing elements of said first group being integrated in a substrate comprising a non-metal material with a melting temperature between 60 and 135 °C,

- applying an overlay of asphalt or bitumen or any other bitumen based material over said structure for the reinforcement of pavements.

Brief Description of the Figure

FIGURE 1 is a top view of a structure according to the present invention.

Mode(s) for Carrying Out the Invention

[0036] FIGURE 1 is a top view of a structure 1 according to the invention. The structure 1 has a substrate 2 to which transverse reinforcing elements that are steel cords 3 are directly or indirectly integrated by being bound to it. The structure 1 has also longitudinal reinforcing steel cords 4. The substrate 2 comprises or consists of a non-metal material with a melting temperature between 60 and 135 °C.

[0037] Direct bounding of the transverse reinforcing elements that are steel cords 4 may be done by means of glue or by means of yams. Indirect bounding may be realized as follows: The transverse reinforcing elements that are steel cords 4 are positioned under the longitudinal reinforcing elements that are steel cords 3 and the longitudinal reinforcing elements that are steel cords 3 are stitched by means of synthetic yarns to the substrate 2.

[0038] The substrate 2 has a width. The substrate 2 has two longitudinal sides. The structure 11 can be used when renovating roads and pavements. [0039] Examples:

Structures according to the present invention have been tested and then analysed by extracting a core or carrot after application asphalt or bitumen or any other bitumen based material to check the state of the structures and the substrates.

Three structures according to the invention with different substrates have been compared, namely:

Example 1 : A non-woven of polypropylene with an amount of substrate of 50 g/m²

Example 2: A non-woven of a co-polyamide with an amount of substrate of 40 g/m²

Example 3: A non-woven of polypropylene with an amount of substrate of 20 g/m² Examination of the core or carrot of reviewed pavement or road application asphalt or bitumen or any other bitumen based material thereby shows the following:

Example 1 : The substrate is still visible.

Example 2: The substrate is not visible anymore.

Example 3: The substrate is still visible.

This shows that despite having a similar melting temperatures, the substrates have different melting behavior. Example 2 and the corresponding substrate can thereby through its melting behavior further contribute to improve the adhesion of new road or pavement layers to old road or pavement layers, especially also when an ARC interlayer is used. .

Claims

1 . A structure for the reinforcement of pavements, said structure having a longitudinal direction and a transverse direction, said structure comprising a first group of reinforcement element, said reinforcement elements of said first group being oriented in a first direction in a mutual parallel or mutual substantially parallel position, said reinforcement elements being integrated in a substrate ,

CHARACTERIZED in that said substrate comprises or consists of a non-metal material with a melting temperature between 60 and 135 °C.

2. A structure according to claim 1 , wherein said substrate consists of a non- metal material with a melting temperature between 75 and 130 °C, preferably between 95 and 115 °C, further preferred between 100 and 110 °C.

3. A structure according to claim 1 or 2, wherein said reinforcement elements are or comprise metal wires, bundles of metal wires or metal cords, carbon fibers, synthetic fibers, basalt fibers, glass fibers or yarns made therefrom, extruded reinforcement elements or the like, especially for example steel cords.

4. A structure according to any one of claims 1 to 3, wherein the non-metal material is selected from the group comprising: polylactic acid (PLA) or polylactic acid copolymers, ethylene-vinyl acetate copolymers (EVA), polypropylene or polypropylene copolymers, polyesters, co-polyesters, polyamids, co-polyamids, thermoplastic polyurethanes and/or wherein the non- metal material is preferably selected from the group comprising: polylactic acid (PLA) or polylactic acid copolymers, ethylene-vinyl acetate copolymers (EVA), polyesters, co-polyesters, polyamids, co-polyamids, thermoplastic polyurethanes and/or wherein substrate is a non-woven or a grid or a film and/or wherein a structure according to the invention may comprise one or more layers of substrate, preferably exactly one layer of substrate.

5. A structure according to any one of claims 1 to 3, wherein said substrate consists of a non-metal material with an MFR at 160 °C and 2.16 kg of between 5 and 600 g/10 min, preferably between 7 and 500 g/10 min preferably between 20 and 250 g/10 min, further preferred between 25 and 65 g/10 min or between 90 and 175 g/10 min and/or wherein the amount of substrate per m² may thereby preferably be for example between 10 and 150 g/m², preferably between 20 and 120 g/m², further preferred between 30 and 90 g/m², further preferred between 40 and 80 g/m².

6. A structure according to any one of the preceding claims, wherein the included angle between said first direction and said longitudinal direction is ranging between -80° and + 80°.

7. A structure according to any one of the preceding claims, wherein said first direction is oriented in the longitudinal direction of said structure.

8. A structure according to any one of the preceding claims, wherein said reinforcing elements are integrated in to said substrate by at least one yarn.

9. A structure according to any one of claims 1 to 7, wherein said reinforcing elements are integrated in a non-woven, woven or knitted substrate or into a film or a grid.

10. A structure according to any one of the preceding claims, whereby said structure comprises a second group of reinforcing elements, said reinforcing elements of said second group being oriented in a second direction, said second direction being different from said first direction, preferably perpendicular to the first direction.

11 . A method to manufacture a structure as defined in any one of claims 1 to 10, said method comprising the steps of

- providing at least a first group of reinforcement elements, 14

- providing non-metal substrate with a melting temperature between 60 and 135 °C;

- coupling said reinforcing elements of said first group to said substrate so that said reinforcing elements are oriented in a first direction in a mutual parallel or mutual substantially parallel position. A method to manufacture a structure for the reinforcement of pavements as defined in any one of claims 1 to 10, said method comprising the steps of

- providing at least a first group of reinforcing elements,

- integrating said reinforcing elements in a substrate comprising non-metal material with a melting temperature between 60 and 135 °C. A structure according to claim 1 , further comprising

- an overlay of asphalt or bitumen or any other bitumen based material applied over said structure for the reinforcement of pavements. A structure according to claim 13 further comprising an interlayer between said pavement and said structure for the reinforcement of pavements and/or between said structure for the reinforcement of pavements and said bitumen overlay. A method of installing a structure for the reinforcement of pavements, said method comprising the steps of