Fiber reinforcement material for cement compositions

Description

1 / 27 Fiber reinforcement material for cementitious compositions. Technical Field

[0001] The invention relates to polymeric fibers for use in building materials, particularly in cementitious compositions. In particular, the invention relates to fiber materials comprising twisted macrosynthetic fibers supplied in the form of a fiber bundle, which fibers are capable of undergoing progressive fibrillation when mechanically agitated within a matrix material to be reinforced. Fundamentals

[0002] Concrete is the most commonly used man-made building material for structural applications in the world. Generally, concrete is a brittle material having high compressive strength but low tensile strength (resistance to cracking). The tensile strength of concrete can be improved using modifying admixtures, such as reinforcing bars and mesh. Polymeric, metallic, glass, and natural fibers have also been used to improve the tensile strength (strength before the first crack occurs) and toughness (resistance to cracking) of concrete.

[0003] Different types of fibers can be used to improve specific properties of concrete. Synthetic microfibers (microfibers) having a linear density not exceeding 580 denier (den) are typically used to prevent plastic shrinkage cracking as the concrete sets, i.e., to prevent microcracks in the concrete during the first 24 to 48 hours after molding. Macrosynthetic fibers (macrofibers) having a linear density greater than 580 denier and diameters equal to or greater than 0.3 mm are added to concrete mixes to improve overall toughness quantified by measurements of residual strength after the first rupture has occurred. Macrofibers are typically added to concrete mixes in fiber dosages of 1.8 to 8.9 kg / m3. Macrofibers are available in various formats, such as rope, tape, or rod, and they can be twisted, serrated, or stamped to intensify the mechanical bond to the concrete. The properties Petition 870250085663, dated 09 / 22 / 2025, page 12 / 46 2 / 27 of the effectiveness of synthetic fiber reinforcement in concrete depends on both the strength of the fiber and the adhesion between the fiber and the concrete matrix.

[0004] The benefits obtained with fiber-reinforced concrete have led to the widespread use of fibers in place of conventional reinforcement for temperature and shrinkage, as well as toughness, in many applications, including slabs over ground. Plastic materials commonly used for concrete reinforcement fibers include polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), aramids, for example Kevlar, polyamides, and polyvinyl alcohol fibers. All of these suffer from one or more disadvantages, such as high cost, low alkaline resistance, low toughness, or poor interfacial bonding between the concrete matrix and the fiber. Polypropylene and polyethylene have been widely used as raw materials for micro and macro fibers. Their advantages include easy fiber processability through melt spinning (extrusion) processes, low cost, and high strength in alkaline environments.However, due to their low density and hydrophobicity, the fibers tend to sprout to the surface during finishing; that is, the fibers tend to protrude from the concrete surface before curing is complete. The interfacial bond between the fiber and the concrete can be controlled using coatings applied to the fiber surface or by chemical modification of the fiber surface. However, these methods generally result in increased costs and complexity of the fiber production process.

[0005] Fibers with a larger fiber ratio are generally more suitable than smaller fibers for use in improving the toughness of concrete. Thicker fibers have greater tensile strength but also provide less interfacial bonding to the concrete due to the reduced surface area. The bonding properties of fibers can generally be improved by using longer and thinner fibers. However, longer and thinner fibers also tend to clump together into balls (pellets) that are difficult to break up when added to concrete. Resistance to pelleting can be improved by using fibers that fibrillate into many fibers. Petition 870250085663, dated 09 / 22 / 2025, page 13 / 46 3 / 27 smaller when mechanically agitated within a matrix material to be reinforced with the fibers. Fibrillation also increases the surface area of ​​the fibers, resulting in improved interfacial bonding to the concrete. Self-fibrillating macrosynthetic fibers consisting of three or more partially fused monofilaments, which are capable of undergoing progressive fibrillation when mechanically agitated within a matrix material to be reinforced, are disclosed in published patent application WO2021255208 A1.

[0006] Another challenge with macrosynthetic fibers, and particularly with autofibrillating fibers, is their uniform distribution in the concrete mix. Uniform fiber distribution is generally achieved by supplying them in the form of pre-packaged fiber “discs” or bundles, encased in a water-soluble polyvinyl alcohol film, from which the individual fibers are released in a controlled manner during mixing, thus providing a more uniform fiber distribution. However, if the fiber bundles are too large, fiber entanglement will still occur.

[0007] In addition, many commercially available autofibrillating fibers exhibit problems with either “over-bonding,” which causes the filaments to never separate properly, or “under-bonding,” which causes the filaments to separate before the fibers are introduced into the concrete mix. Inconsistency in fiber autofibrillation can affect individual fiber count, alter slump in the concrete mix, concrete performance, and concrete finishing characteristics.

[0008] Thus, there is still a need for new and improved solutions that overcome the aforementioned disadvantages as far as possible. Summary of the invention

[0009] The objective of the present invention is to provide an improved fiber reinforcement material for use in cementitious compositions, particularly in concrete mixes.

[0010] Surprisingly, it was found that the objective can be Petition 870250085663, dated 09 / 22 / 2025, page 14 / 46 4 / 27 achieved by the characteristic of claim 1.

[0011] Specifically, according to the invention, a fiber reinforcement material is proposed, the material comprising a plurality of macrosynthetic fibers twisted to form a fiber bundle with a degree of twist of 5 to 100 t / m (turns per meter), preferably 8 to 80 t / m, wherein at least a portion of the macrosynthetic fibers are autofibrillating fibers consisting of two or more partially fused polymeric monofilaments and having a multilobal cross-sectional shape with two or more lobes.

[0012] As it turned out, the fiber reinforcement material composed of self-fibrillating macrosynthetic fibers supplied in the form of a bundle of twisted fibers shows consistent self-fibrillating properties, reduced fiber entanglement (ball formation) and good finish of concrete slabs, even when used in the high quantities required for structural reinforcement, such as in quantities of 3.6 to 4 kg of fibers / m3 of concrete mix.

[0013] Additional aspects of the present invention are presented in additional independent claims. Preferred embodiments of the invention are outlined throughout the description and dependent claims. Brief Description of the Drawings

[0014] Fig. 1 shows schematically a cross-sectional shape of an exemplary autofibrillating macrosynthetic fiber.

[0015] Fig. 2 shows a schematic representation of an exemplary process for producing a self-fibrillating macrosynthetic fiber. Detailed Description of the Invention

[0016] A first aspect of the present invention is directed to a fiber reinforcement material comprising a plurality of macrosynthetic fibers twisted to form a fiber bundle with a degree of twist of 5 to 100 t / m, preferably 8 to 80 t / m, wherein at least a portion of the macrosynthetic fibers are autofibrillating fibers consisting of two or more partially fused polymeric monofilaments and having a multilobal cross-sectional shape with two or more lobes. Petition 870250085663, dated 09 / 22 / 2025, page 15 / 46 5 / 27

[0017] The term polymer refers to a collection of chemically uniform macromolecules produced by a polyreaction (polymerization, polyaddition, polycondensation) where the macromolecules differ in relation to their degree of polymerization, molecular weight and chain length. The term also includes derivatives of the aforementioned collection of macromolecules resulting from polyreactions, that is, compounds that are obtained by reactions, such as, for example, additions or substitutions, of functional groups in predetermined macromolecules and that may be chemically uniform or chemically non-uniform.

[0018] The term melting temperature refers to the temperature at which a material undergoes a transition from the solid to the liquid state. The melting temperature (Tm) is preferably determined by differential scanning calorimetry (DSC) according to the ISO 11357 standard using a heating rate of 2 °C / min. Measurements can be performed with a Mettler Toledo DSC 3+ device, and the Tm values ​​can be determined from the measured DSC curve using DSC software. If the measured DSC curve shows multiple peak temperatures, the first peak temperature from the lower temperature side of the thermogram is considered the melting temperature (Tm).

[0019] The quantity or content of at least one component X in a composition, for example, the quantity of at least one thermoplastic polymer P1, refers to the sum of the individual quantities of all thermoplastic polymers P1 contained in the composition. For example, in the case of a composition comprising 20% ​​by weight of at least one thermoplastic polymer P1, the sum of the quantities of all thermoplastic polymers P1 contained in the composition is equal to 20% by weight.

[0020] Room temperature refers to a temperature of 23°C.

[0021] The fiber reinforcement material of the present invention comprises a plurality of macrosynthetic fibers twisted to form a fiber bundle with a degree of twist of 5 to 100 t / m, preferably 8 to 80 t / m, more Petition 870250085663, dated 09 / 22 / 2025, p. 16 / 46 6 / 27 preferably 15 to 75 t / m, even more preferably 25 to 70 t / m, even more preferably 30 to 65 t / m, especially 35 to 60 t / m, for example 40 to 60 t / m.

[0022] At least a portion of the macrosynthetic fibers twisted to form a fiber bundle are autofibrillating fibers consisting of two or more, preferably three or more, partially fused polymeric monofilaments and having a multilobal cross-sectional shape with two or more lobes, preferably three or more lobes.

[0023] The expression “partially fused” is understood in the context of the present invention to mean that the autofibrillating fibers were obtained by means of a process comprising extruding a molten polymer composition to provide extruded monofilaments, which may contact over a portion of their primary outer surfaces and partially fuse together to form an unstretched fiber. The term primary outer surface of a filament refers to the longitudinally extending surface of said filament.

[0024] Autofibrillating fibers composed of partially fused monofilaments differ significantly from fibers composed of a single filament (monofilament fibers) and from multifilament fibers, where the filaments have been joined together adhesively or mechanically.

[0025] In one or more embodiments, the autofibrillating fibers contained in the fiber reinforcement material were obtained using a process comprising extruding a molten polymer composition through an extruder die comprising a plurality of holes to provide unstretched fibers, wherein at least some of the holes consist of a set of two or more holes, preferably three or more holes that are arranged closely but not overlapping, such that when the molten polymer composition is extruded through the holes, the extruded monofilaments thus obtained are partially fused to form an unstretched fiber. The term overlapping is understood to mean that the distance Petition 870250085663, dated 09 / 22 / 2025, p. 17 / 46 The distance between adjacent holes in the aforementioned assembly is such that the perimeters of the holes do not intersect.

[0026] Due to the partially fused filament structure, autofibrillating fibers are particularly capable of undergoing progressive fibrillation when mechanically agitated within a matrix to be reinforced with the fibers. The first part of the fibrillation occurs during the initial mixing stage, which gives the fibers additional time to disperse within the matrix. The second part of the fibrillation occurs after considerable mixing, when a significant portion of the fibers has already been distributed in the matrix, which decreases the tendency of the individual monofilaments separated from the fibers to clump together into balls.

[0027] In one or more embodiments, the fiber reinforcement material was obtained by a process comprising twisting together 2 to 100, preferably 5 to 75, more preferably 5 to 50, even more preferably 5 to 35, even more preferably 6 to 25 macrosynthetic fibers in a twisted bundle using a degree of twist of 5 to 100 t / m, preferably 8 to 80 t / m, more preferably 15 to 75 t / m, even more preferably 25 to 70 t / m, even more preferably 30 to 65 t / m, especially 35 to 60 t / m, for example 40 to 60 t / m.

[0028] It may be preferable that autofibrillating fibers have a linear density of at least 500 den, more preferably at least 1000 den. The term den is an abbreviation of denier, which refers to a unit of measurement for the linear mass density of fibers, that is, the mass in grams per 9000 meters of fiber.

[0029] In one or more forms, autofibrillating fibers have: - a linear density of 500 to 10000 den, preferably 800 to 7500 den, more preferably 1500 to 6500 den, even more preferably 2000 to 5000 den, even more preferably 2500 to 4000 den and / or - a length of at least 15 mm, preferably at least 20 mm, more preferably at least 25 mm, even more Petition 870250085663, dated 09 / 22 / 2025, page 18 / 46 8 / 27 preferably at least 30 mm, even more preferably at least 35 mm and / or - a length not exceeding 100 mm, preferably not exceeding 85 mm, more preferably not exceeding 70 mm, even more preferably not exceeding 65 mm, and even more preferably not exceeding 60 mm and / or

[0030] In particular, the polymeric composition of the autofibrillating fibers may comprise at least 70% by weight, preferably at least 75% by weight of at least one polypropylene.

[0031] In one or more embodiments, the polymer composition comprises 70 to 95% by weight, preferably 75 to 90% by weight, more preferably 80 to 90% by weight, of at least one polypropylene.

[0032] Polypropylenes suitable for use in polymer composition include polypropylene homopolymers (hPP), such as isotactic polypropylene (iPP) and syndiotactic polypropylene (sPP), as well as propylene copolymers, such as heterophasic propylene copolymers, random propylene copolymers, and propylene block copolymers.

[0033] The term propylene copolymer refers to copolymers comprising at least 50% by weight, more preferably at least 60% by weight of propylene-derived units, based on the weight of the copolymer, while the term ethylene copolymer refers to copolymers comprising at least 50% by weight, more preferably at least 60% by weight of ethylene-derived units, based on the weight of the copolymer.

[0034] Heterophasic propylene copolymers are heterophasic polymer systems comprising a highly crystalline base polyolefin and an amorphous or low-crystallinity polyolefin modifier. The morphology of the heterophasic phase consists of a matrix phase composed primarily of the polyolefin base and a dispersed phase composed primarily of the polyolefin modifier. Available heterophasic propylene copolymers Petition 870250085663, dated 09 / 22 / 2025, page 19 / 46 Commercially suitable 9 / 27 include reactor blends of base polyolefin and polyolefin modifier, also known as in situ TPOs or reactor TPOs or impact copolymers (ICP), which are typically produced in a sequential polymerization process, where the matrix phase components are produced in a first reactor and transferred to a second reactor, where the dispersed phase components are produced and incorporated as domains in the matrix phase. Heterophasic propylene copolymers comprising polypropylene homopolymer as the base polymer are often referred to as heterophasic propylene copolymers (HECO), while heterophasic propylene copolymers comprising polypropylene random copolymer as the base polymer are often referred to as heterophasic random propylene copolymers (RAHECO).The term heterophasic propylene copolymer in this disclosure encompasses both the HECO and RAHECO types of heterophasic propylene copolymers.

[0035] Specifically, at least one polypropylene can have: - a bending modulus determined in accordance with ISO 178:2019 of at least 1000 MPa, preferably at least 1100 MPa, more preferably at least 1200 MPa and / or - a melting temperature (Tm) determined by differential scanning calorimetry (DSC) according to ISO 11357-3:2018 standard using a heating rate of 2 °C / min equal to or greater than 115°C, preferably equal to or greater than 125°C, more preferably equal to or greater than 135°C, even more preferably equal to or greater than 145°C, even more preferably equal to or greater than 155°C and / or - a melt flow rate (230 °C / 2.16 kg) determined according to ISO 1133 standard of not more than 100 g / 10 min, preferably not more than 50 g / 10 min, more preferably not more than 35 g / 10 min, even more preferably not more than 15 g / 10 min, such as 0.5 - 15 g / 10 min, preferably 1 - 10 g / 10 min, more preferably 1 - 5 g / 10 min.

[0036] In one or more embodiments, at least one polypropylene Petition 870250085663, dated 09 / 22 / 2025, page 20 / 46 10 / 27 comprises or consists of a polypropylene homopolymer, preferably an isotactic polypropylene, preferably having an isotactic index determined by 13C-NMR spectroscopy of at least 80%, preferably at least 85%, more preferably at least 90%.

[0037] The polymeric composition of autofibrillating fibers may further comprise at least 1% by weight, preferably at least 5% by weight, more preferably at least 7.5% by weight, of at least one polyethylene. Without being bound to any theory, it is believed that, due to the polymeric composition of polypropylene and polyethylene composite monofilaments, the boundary between partially fused monofilaments is more easily broken than in the case of monofilaments composed only of polyethylene or polypropylene. This is believed to increase the ability of the fibers to undergo progressive fibrillation when mechanically agitated within a matrix to be reinforced with the fibers.

[0038] In one or more embodiments, the polymeric composition of the autofibrillating fibers comprises 1 to 30% by weight, preferably 5 to 25% by weight, more preferably 10 to 20% by weight, of at least one polyethylene.

[0039] Polyethylenes suitable for use in polymeric material include ethylene homopolymers and ethylene copolymers.

[0040] According to one or more modalities, at least one polyethylene has: - a melting temperature (Tm), determined by differential scanning calorimetry (DSC) according to ISO 11357-3 using a heating rate of 2 °C / min, equal to or greater than 90 °C, preferably equal to or greater than 100 °C, more preferably equal to or greater than 105 °C, such as 90 to 140 °C, preferably 100 to 135 °C, more preferably 105 to 125 °C and / or - a melt flow rate (190 °C / 2.16 kg) determined according to ISO 1133 standard of not more than 100 g / 10 min, preferably not more than 50 g / 10 min, more preferably not more than 35 g / 10 min, even more Petition 870250085663, dated 09 / 22 / 2025, p. 21 / 46 11 / 27 preferably no more than 15 g / 10 min, such as 0.5 to 15 g / 10 min, preferably 1 to 10 g / 10 min, more preferably 1 to 5 g / 10 min.

[0041] In one or more embodiments, at least one polyethylene comprises or consists of low-density polyethylene (LDPE) or linear low-density polyethylene (LLDPE), or high-density polyethylene (HDPE), preferably linear low-density polyethylene (LLDPE).

[0042] It may be preferable that the fiber bundle of the fiber reinforcement material of the present invention contain, in addition to the autofibrillating fibers discussed above, also other types of macrosynthetic fibers, such as monofilament fibers. In these embodiments, the monofilament fibers can be twisted together with the autofibrillating fibers to form the fiber bundle.

[0043] Preferably, the ratio of autofibrillating fibers comprises at least 5% by weight, more preferably at least 10% by weight, even more preferably at least 15% by weight, of the total weight of macrosynthetic fibers in the fiber bundle.

[0044] Monofilament fibers can be composed of a polymeric composition similar to that of autofibrillating fibers.

[0045] In particular, monofilament fibers may be composed of a polymer composition comprising at least 70% by weight, preferably at least 75% by weight, of at least one polypropylene.

[0046] In one or more embodiments, the polymeric composition of the monofilament fibers comprises 70 to 95% by weight, preferably 75 to 90% by weight, more preferably 80 to 90% by weight, of at least one polypropylene.

[0047] The polymeric composition of the monofilament fibers may further comprise at least 1% by weight, preferably at least 5% by weight, more preferably at least 7.5% by weight, of at least one polyethylene.

[0048] In one or more embodiments, the polymeric composition of the monofilament fibers comprises 1 to 30% by weight, preferably 5 to 25% in Petition 870250085663, dated 09 / 22 / 2025, page 22 / 46 12 / 27 by weight, more preferably 10 to 20% by weight, of at least one polyethylene.

[0049] In one or more embodiments, at least a portion of the monofilament fibers twisted together with the autofibrillating fibers are composed of the same polymer composition as the autofibrillating fibers.

[0050] In one or more embodiments, macrosynthetic fibers are superficially structured on their outer surfaces. In particular, macrosynthetic fibers may comprise indentations and / or reliefs on their outer surface and / or the outer surfaces of macrosynthetic fibers may be coated with particles. The surface structure may be obtained, for example, by means of stamping, grinding, sandblasting and / or coating techniques, for example, with sand particles.

[0051] In particular, macrosynthetic fibers may have their surface structured on their outer surfaces such that a square-mean roughness Rq (λ = 800 μm, 50 times magnification) of the surface is from 1 to 100 pm, preferably from 2 to 80 pm, more preferably from 3 to 60 pm, particularly from 5 to 40 pm, wherein Rq is measured according to the ISO 4287:1997 standard.

[0052] Furthermore, crimping has been found to reduce the stiffness of macrosynthetic fibers and improve autofibrillation properties. Generally, the number of crimps must be high enough to provide the fiber with enhanced fibrillation properties without negatively impacting other properties, such as fiber dispersion properties.

[0053] In one or more forms, macrosynthetic fibers have: - a crimping frequency of 5 to 100 crimps / 100 mm, preferably 15 to 85 crimps / 100 mm, more preferably 20 to 80 crimps / 100 mm, even more preferably 25 to 75 crimps / 100 mm and / or - a crimping amplitude of 0.1 to 1 mm, preferably 0.2 to 1 mm, more preferably 0.5 to 1 mm, and even more preferably 0.6 to 0.8 mm. Petition 870250085663, dated 09 / 22 / 2025, page 23 / 46 13 / 27

[0054] In one or more embodiments, at least a portion of the macrosynthetic fibers are autofibrillating fibers that have a multilobal cross-sectional shape with two or more lobes, preferably three or more lobes, and a central section that runs axially through the fiber.

[0055] The central section of the autofibrillating fibers is preferably solid, that is, it does not include an axial hole or a void. According to one or more embodiments, at least two of said lobes extend outward, preferably radially from the central section. According to one or more embodiments, at least two of said lobes are connected to each other through the central section.

[0056] Preferably, each lobe has a tip portion and a base portion situated towards the central section of the fiber. In addition, the tip portion of each lobe is preferably curved, more preferably curved in a convex manner. Figure 1 schematically shows the cross-sectional shape of an exemplary autofibrillating fiber composed of four partially fused polymeric monofilaments, wherein the fiber (1) has a quadrilobed cross-sectional shape with four lobes (2) extending outward from the central section (3) of the fiber.

[0057] According to one or more embodiments, the base portion of each lobe has a width (D2) that is less than the maximum width (D1) of the tip portion. The term maximum width of the tip portion refers to the length of the longest line extending perpendicularly to a longitudinal line connecting the center section of the fiber with the tip portion of the lobe, wherein the longitudinal line extends towards the lobe contour. The term width of the base portion refers to the length of a line connecting two endpoints of the base portion of two adjacent lobes. In Figure 1, the maximum width of the tip portion of a lobe (2) is indicated by the letter “D1”, the width of the base portion of the lobe (2) is indicated by the letter “D2”, and the length of the longitudinal line connecting the center section (3) of the fiber with the tip portion of the lobe (2) is indicated by the letter “L”. The widths D1 and D2 Petition 870250085663, dated 09 / 22 / 2025, p. 24 / 46 14 / 27 can be determined from a microscopic image of a cross-section of the fiber.

[0058] According to one or more embodiments, in each lobe, the ratio between the maximum width of the tip portion and the width of the base portion (D1:D2) is from 1.1:1 to 3:1, preferably from 1.2:1 to 2.7:1, more preferably from 1.3:1 to 2.5:1. Autofibrillating fibers with the ratio between the maximum width (D1) of the tip portion and the width (D2) of the base portion in the ranges mentioned above have been shown to be advantageous, since the lobes, and therefore the partially fused monofilaments of the fiber, tend to be detached or separated from the base portion by shear force, thus allowing progressive fibrillation when the fibers are mechanically agitated within a matrix material to be reinforced.

[0059] According to one or more embodiments, at least a portion of the macrosynthetic fibers are autofibrillating fibers composed of four partially fused polymeric monofilaments. In these embodiments, at least a portion of the macrosynthetic fibers are autofibrillating fibers with a quadrilobed cross-sectional shape with four lobes, wherein preferably at least two of the lobes extend outward, more preferably radially from the central section of the fiber. These autofibrillating fibers, when twisted to form a fiber bundle, have been found to be highly effective in improving the toughness of concrete and exhibit good dispersibility in a concrete mix and good surface finishing properties.According to one or more embodiments, at least a portion of the macrosynthetic fibers are autofibrillating fibers that have a quadrilobed cross-sectional shape with four lobes extending outward, preferably radially, from the central section of the fiber.

[0060] It may be preferable for the autofibrillating fibers to have: - a modulus of elasticity, a modulus of elasticity determined at 23 °C and a shear rate of 5 % / min according to EN 14889-2:2006 Petition 870250085663, dated 09 / 22 / 2025, page 25 / 46 15 / 27 standard of at least 5 MPa, preferably at least 7 MPa and / or - an elongation at break determined at 23 °C according to EN 10002-1:2001 standard not exceeding 15%, preferably not exceeding 10% and / or - a tensile strength determined at 23 °C and a shear rate of 5 % / min according to EN 14889-2:2006 standard of at least 250 MPa, preferably at least 350 MPa.

[0061] Autofibrillating fibers are preferably stretched with a stretch ratio of at least 5:1, more preferably 10:1. Stretching results in the orientation of the polymer chains in a longitudinal direction of the fiber, which increases tensile strength and decreases fiber elongation. In addition, stretched fibers are typically less stretchable in the width direction. Finally, stretching also weakens the connection region between partially fused monofilaments, resulting in more effective fibrillation during mixing with a concrete matrix.

[0062] According to one or more embodiments, autofibrillating fibers were stretched uniaxially with a stretch ratio of 7.5:1 to 25:1, preferably 10:1 to 20:1, more preferably 10:1 to 17.5:1, even more preferably 12:1 to 15:1.

[0063] Preferably, the autofibrillating fibers are separable into single monofilaments with a linear density not exceeding 1250 den, preferably not exceeding 1000 den, more preferably not exceeding 900 den.

[0064] According to one or more embodiments, autofibrillating fibers are separable into single monofilaments having: - a linear density of 150 to 1250 den, preferably 250 to 1150 den, more preferably 350 to 1000 den, even more preferably 400 to 950 den and / or - an aspect ratio (l / d) of 100 to 250, preferably 105 to 200, more preferably 110 to 175, even more preferably 115 to 150 and / or Petition 870250085663, dated 09 / 22 / 2025, p. 26 / 46 16 / 27 - an equivalent diameter determined in accordance with standard EN 14889-2:2006 of 0.1 to 1.0 mm, preferably 0.15 to 0.85 mm, more preferably 0.2 to 0.7 mm, even more preferably 0.2 to 0.55 mm.

[0065] A further aspect of the present invention is directed to a method for producing a fiber reinforcement material of the present invention, the method comprising twisting together 2 to 100, preferably 5 to 75, more preferably 5 to 50, even more preferably 5 to 35, even more preferably 6 to 25 macrosynthetic fibers into a twisted bundle using a degree of twist of 5 to 100 t / m, preferably 8 to 80 t / m, more preferably 15 to 75 t / m, even more preferably 25 to 70 t / m, even more preferably 30 to 65 t / m, especially 35 to 60 t / m, for example 40 to 60 t / m, wherein at least a portion of the macrosynthetic fibers are autofibrillating fibers consisting of two or more partially fused polymeric monofilaments and having a multilobal cross-sectional shape with two or more lobes.

[0066] In the inventive method, the autofibrillating fibers are defined and configured as described above in connection with the first aspect of the present invention.

[0067] Suitable methods for providing autofibrillating fibers are disclosed in a published patent application WO2021255208 A1, particularly from page 15, line 12 to page 20, line 29.

[0068] In one or more embodiments, the method for producing a fiber reinforcement material comprises the steps of: I) Extruding a molten polymer composition comprising a polymer composition through an extruder die to provide unstretched fibers consisting of two or more, preferably three or more, partially fused monofilaments, II) Uniaxially stretch the unstretched fibers obtained in step I) to provide stretched fibers, III) Optionally, crimp and / or embed the stretched fibers obtained in Petition 870250085663, dated 09 / 22 / 2025, page 27 / 46 17 / 27 stage II) to provide crimped and / or riveted fibers, IV) Twist the fibers obtained in step II) or III) into fiber bundles, and IV) Cut the twisted bundles obtained in step IV) to a predetermined length.

[0069] Fiber crimping can be performed using any conventional crimping apparatus, such as a crimping box, for example, a trailer crimping machine. In the case of a crimping box, the drawn fibers are loaded into the crimping box which fills and bends the crimps onto the fibers. Drawn fibers can also be crimped mechanically by passing the fibers through a gear or set of gears to provide crimps onto the fibers.

[0070] The term “relief” refers to a treatment method where fibers are subjected to a compressive force, for example, by placing the fibers between engraved rollers, to cut or roughen the outer surface of the fibers.

[0071] Twisting fibers into fiber bundles can be carried out using any conventional techniques known to a specialist, such as the use of a two-in-one twisting machine or a ring twisting machine.

[0072] Figure 2 shows a schematic presentation of an exemplary method for producing the fiber reinforcement material of the present invention. In the process, the constituents of the initial composition are fed using a dosing and feeding apparatus (1) into an extruder apparatus (2), where the initial composition is melt-processed into a molten polymer composition. The melt-processed starting composition is extruded through a die (3) comprising a plurality of die holes. The extruded fibers are then conveyed through an air gap to a water bath (4). The cooled fibers are conveyed from the water bath (4) to a first (stretching) furnace (6) using a motorized removal roller comprising a first roller support (5). The unstretched fibers are Petition 870250085663, dated 09 / 22 / 2025, page 28 / 46 18 / 27 oriented in the first (stretching) furnace (6), stretched using a second roll support (7) and subsequently processed in a second (annealing) furnace (8). Heating in the first and second furnaces (6, 8) is preferably achieved with forced hot air at a controlled temperature.

[0073] The drawn fibers are passed from the second furnace (8) through a mechanical crimper (9) consisting of two matching rollers that partially engage to deform the drawn fiber. The crimped fibers are conveyed from the crimper using a third roller support (10), wound using a winder (11), twisted using a twisting machine and cut to a predetermined length (not shown in Figure 2).

[0074] Another aspect of the present invention is the use of the fiber reinforcement material of the present invention to improve the properties, preferably the toughness, of a hardened cementitious composition.

[0075] The term cementitious composition refers in this disclosure to concrete, shotcrete, mortar, grout, paste, or a combination thereof. The terms paste, mortar, concrete, shotcrete, and grout are well-known terms to those skilled in the art. Pastes are mixtures comprising a hydratable cement binder, usually Portland cement, masonry cement, or mortar cement. Mortars are pastes that additionally include fine aggregates, for example, sand. Concrete is mortar that additionally includes coarse aggregates, for example, gravel or stone. Shotcrete is concrete (or sometimes mortar) conveyed through a hose and pneumatically projected at high speed onto a surface. Mortar is a particularly fluid form of concrete used to fill gaps.Cementitious compositions can be formed by mixing the necessary quantities of certain components, for example, Portland cement, water, and fines and / or coarse aggregate, to produce a specific cementitious composition.

[0076] According to one or more modalities, the composition Petition 870250085663, dated 09 / 22 / 2025, page 29 / 46 19 / 27 Cementitious material is selected from the group consisting of concrete, shotcrete, mortar and mortar, preferably concrete and shotcrete, more preferably concrete.

[0077] According to one or more embodiments, the fiber reinforcement material is added to the cementitious composition in an amount of 0.1 to 3.0% by volume, preferably 0.2 to 2.0% by volume, more preferably 0.2 to 1.0% by volume, based on the total volume of the hardened cementitious composition.

[0078] According to one or more embodiments, the toughness of the hardened cementitious composition, measured as residual strength after the occurrence of the first rupture, is improved by at least 5%, preferably by at least 10%, more preferably by at least 15%, compared with the toughness of a hardened cementitious composition that does not contain the fiber reinforcement material of the present invention.

[0079] Yet another object of the present invention is the cementitious material comprising: a) A ligand, b) 0.1 to 3.0% by volume, preferably 0.2 to 2.0% by volume, more preferably 0.2 to 1.0% by volume, based on the total volume of the cementitious material, of the fiber reinforcement material of the present invention, c) Aggregates, and d) Water.

[0080] According to one or more embodiments, the binder a) is selected from the group consisting of hydraulic binders, non-hydraulic binders, latent hydraulic binders and pozzolanic binders.

[0081] The term hydraulic binder refers to substances that react with water in a hydration reaction under the formation of solid mineral hydrates or hydrate phases, which are not soluble in water or have low solubility in water. Therefore, hydraulic binders, such as Portland cement, can harden and maintain their strength even when exposed to Petition 870250085663, dated 09 / 22 / 2025, pp. 30 / 46 20 / 27 water, for example, underwater or under conditions of high humidity. In contrast, the term “non-hydraulic binder” refers to substances that harden by reaction with carbon dioxide and therefore do not harden under humid conditions or underwater.

[0082] Examples of suitable hydraulic binders include hydraulic cements and hydraulic lime. The term hydraulic cement here refers to mixtures of silicates and oxides, including alite, belite, tricalcium aluminate and brownmillerite.

[0083] Commercially available hydraulic cements can be divided into five main types of cement according to the DIN EN 197-1 standard, namely, Portland cement (CEM I), Portland composite cements (CEM II), blast furnace cement (CEM III), pozzolan cement (CEM IV) and composite cement (CEM V). These five main types of hydraulic cement are subdivided into a further 27 types of cement, which are known to those skilled in the art and listed in DIN EN 197-1. Naturally, all other hydraulic cements that are produced according to another standard, for example, according to the ASTM standard or Indian standard, are also suitable.

[0084] Examples of suitable non-hydraulic binders include air-slaked lime (non-hydraulic lime) and gypsum. The term gypsum refers in this disclosure to any known form of gypsum, in particular dehydrated calcium sulfate, α-hemihydrate calcium sulfate, β-hemihydrate calcium sulfate or anhydride calcium sulfate or mixtures thereof.

[0085] The term latent hydraulic binder refers in this disclosure to type II concrete admixtures with a latent hydraulic character as defined in the DIN EN 206-1:2000 standard. These types of mineral binders are calcium aluminosilicates that are unable to harden directly or harden very slowly when mixed with water. The hardening process is accelerated in the presence of alkaline activators, which break the chemical bonds in the amorphous (or glassy) phase of the binder and promote the dissolution of ionic species and the formation of hydrate phases. Petition 870250085663, dated 09 / 22 / 2025, page 31 / 46 21 / 27 calcium aluminosilicate.

[0086] Examples of suitable latent hydraulic binders include ground granulated blast furnace slag. Ground granulated blast furnace slag is typically obtained by quenching molten iron slag from a blast furnace in water or steam to form a glassy granular product and then drying and grinding the glassy product into a fine powder.

[0087] The term pozzolanic binder refers in this disclosure to type II concrete admixtures with a pozzolanic character as defined in the DIN EN 206-1:2000 standard. These types of mineral binders are siliceous or aluminosilicate compounds that react with water and calcium hydroxide to form calcium silicate hydrate or calcium aluminosilicate hydrate phases.

[0088] Examples of suitable pozzolanic binders include natural pozzolans, such as trass, and artificial pozzolans, such as fly ash and silica fume. The term fly ash refers in this disclosure to the finely divided ash residue produced by the combustion of pulverized coal, which is carried with the exhaust gases from the furnace in which the coal is burned. The term silica fume refers in this disclosure to fine particles of silicon in an amorphous form. Silica fume is typically obtained as a byproduct of silica ore processing, such as quartz smelting in a silica smelter, which results in the formation of gaseous silicon monoxide and which, upon exposure to air, further oxidizes to produce small particles of amorphous silica.

[0089] According to one or more embodiments, the binder is a hydraulic binder, preferably a hydraulic cement, such as Portland cement.

[0090] Suitable aggregates for use in cementitious material include coarse and fine aggregates (sand), as well as pebbles and rocks of various sizes, typically in the range of 10 mm to 20 mm (3 / 8” - 3 / 4”). According to one or more embodiments, cementitious material is a composition of Petition 870250085663, dated 09 / 22 / 2025, page 32 / 46 22 / 27 fiber-reinforced concrete.

[0091] According to one or more embodiments, the weight ratio of the amount of water to the amount of binder is in the range of 0.2:1 to 0.7:1, preferably 0.3:1 to 0.6:1, more preferably 0.4:1 to 0.6:1, even more preferably 0.45:1 to 0.55:1.

[0092] Yet another object of the present invention is a method for forming a concrete surface comprising the steps of: I. Adding fiber-reinforcing material of the present invention to a fluidized concrete mix under mixer rotation to provide a modified concrete mix. II. Melt the modified concrete mixture prepared in step I to provide a molded concrete body. III. Smooth the surface of the molded concrete body prepared in step II., and IV. Cure the modified concrete mix.

[0093] According to one or more embodiments, the said fluidized concrete mixture comprises a binder, aggregates and water.

[0094] The weight ratio between the amount of water and the amount of binder is preferably in the range of 0.2:1 to 0.7:1, more preferably from 0.3:1 to 0.6:1, even more preferably from 0.4:1 to 0.6:1, even more preferably from 0.45:1 to 0.55:1.

[0095] Preferred binders and aggregates have already been discussed above in relation to the cementitious material of the present invention.

[0096] According to one or more embodiments, the modified concrete mix comprises 0.1 to 3.0% by volume, preferably 0.2 to 2.0% by volume, more preferably 0.2 to 1.0% by volume, of fiber reinforcement material, based on the total volume of the hardened cementitious composition.

[0097] The smoothing of the surface of the cast concrete body can be carried out, for example, using a pallet or a trowel. Examples Petition 870250085663, dated 09 / 22 / 2025, pp. 33 / 46 23 / 27

[0098] The following compounds shown in Table 1 were used in the examples: Table 1 Polypropylene Homopolymer PP isotactic, melt flow rate (230°C, 2.16 kg) 2 g / 10 min, melting point (ASTM D1238) 164°C. Polyethylene LLDPE, melt flow rate (190°C, 2.16 kg) 0.9 g / 10 min, density 0.918 g / cm3 (ASTM D1505). Additive: Gray pigment. Model I / II cement. Coosa - Leeds, AL. Natural sand. Lambert Sand Co. #57 granite stone. Vulcan - Lithonia, GA. Drinking water. Lawrenceville, GA. Preparation of fiber reinforcement material

[0099] The autofibrillating fibers used to prepare the inventive and reference fiber reinforcement materials were produced using a process that is shown schematically in Figure 2.

[0100] The ratio of raw materials, production process parameters, as well as the dimensions and mechanical properties of autofibrillating fibers are shown in Table 2.

[0101] All autofibrillating fibers were produced using an extruder die with a plurality of spinnerets, where each spinneret hole consisted of a set of four non-intersecting round holes arranged in a quadrilateral shape. The fibers produced had a multilobal cross-sectional shape with four lobes extending radially from the center of the fiber, as shown schematically in Figure 1.

[0102] The raw materials for autofibrillating fibers were fed Petition 870250085663, dated 09 / 22 / 2025, pages 34 / 46 24 / 27 using a dosing and feeding apparatus (1) in an extruder (2) comprising a 110 mm single screw extruder with an L / D ratio of 32:1 and two melt pumps feeding two circular dies. The melt-processed composition was extruded through an extrusion die (3) comprising a plurality of spinnerets consisting of a set of orifices and the extruded fibers were conveyed through an air gap to a water bath (4). The downstream equipment was a motorized take-off roller comprising a first roller support (5) fitted with five rollers and a clamping roller on the output roller.

[0103] The unstretched fibers obtained from the output roll were oriented in a first (stretching) furnace (6), stretched using a second roll support (7) composed of seven rolls and subsequently processed in a second (annealing) furnace (8) to obtain stretched fibers. Heating in the first and second furnaces (6, 8) was carried out with forced hot air at controlled temperature.

[0104] The drawn fibers obtained in the second furnace (8) were passed through a mechanical crimper (9) composed of two coupled rollers that partially engage to deform the drawn fiber. After exiting the crimper (9), the fibers were subsequently processed through the third roller support (10) composed of seven rollers, with the exit roller having a clamping roller.

[0105] The inventive fiber reinforcement material (Ex-1) was obtained by twisting 15 individual stretched and crimped fibers using a twister (12) into fiber bundles comprising a degree of twist of 54 t / m. The fiber bundles were then wound using a winder (11) and cut to a predetermined length.

[0106] In the case of the reference fiber reinforcement materials (Ref-1, Ref-2), the drawn and corrugated fibers were not twisted into fiber bundles, but wound and cut to a predetermined length and supplied in the form of fiber discs containing the fibers wrapped in a polyvinyl alcohol film. Petition 870250085663, dated 09 / 22 / 2025, pages 35 / 46 25 / 27 water-soluble. The fiber discs of the reference materials had a diameter of 30 mm and 20 mm, respectively. Table 2 Polymer composition [% weight] Ex-1 Polypropylene 79 Polyethylene (LLDPE) 20 Additive 1 Process Hole geometry 4 round holes without intersection in quadrilateral shape (multifilament) Hole diameter [mm] 1.25 Hole spacing < 1.25 mm Extruder profile temperature [°C] 210-235 Extrusion line speed [fps] 149 Stretch ratio 14:1 Stretch oven temperature [°C] 141 Annealing oven temperature [°C] 143 Fiber properties Fiber length [mm] 38 D1:D2 ratio 2 Deformation type Crimping Linear density [den] 2800 Tensile strength (undeformed) [MPa] 587 Petition 870250085663, dated 09 / 22 / 2025, pages 36 / 46 26 / 27 Elongation (undeformed) [%] 8 Elastic modulus (undeformed) [GPa] 12.7 Tensile strength (deformed) [MPa] 567 Elongation (deformed) [%] 9.3 Elastic modulus (deformed) [GPa] 8.5 Use of fiber materials in cementitious material

[0107] The objective was to study the effect of torsion on autofibrillation efficiency, entanglement behavior (formation of balls) and fiber finishing capacity.

[0108] The inventive and reference fiber reinforcement materials were first mixed into a typical concrete mix with a compressive strength of 24 to 31 MPa at 7 days of age.

[0109] The concrete was proportioned and mixed in accordance with ASTM C192-19 Standard Practice for Manufacturing and Curing Concrete Test Specimens in the Laboratory. Fiber reinforcement materials were added at the beginning of the batch sequence and mixed with the rock and sand for one minute before the addition of the cementitious material. The concrete was then mixed for 3 minutes, left to stand for 3 minutes, mixed for another 2 minutes, and cast into molds.

[0110] Table 3 shows the frequency of occurrence of ball formation obtained with the fiber reinforcement materials and the ratio (% by weight) of non-completely fibrillated fibers and fully fibrillated fibers after mixing the tested fiber reinforcement material with the concrete mix. In calculating the proportions, fibers with two, three, or four fused monofilaments were considered "non-completely fibrillated fibers" and fibers composed of a single monofilament were considered "fully fibrillated fibers". Table 3 Petition 870250085663, dated 09 / 22 / 2025, pp. 37 / 46 27 / 27 Ref-1 Ref-2 Ex-1 Fiber reinforcement material Untwisted fibers, disc diameter 30 mm Untwisted fibers, disc diameter 20 mm Twisted fiber bundles with 15 fibers Applications with significant balling [%] 27 17 0 Applications with minimal balling [%] 29 0 0 Total occurrence of balls [%] 56 17 0 Proportion of fibers not completely fibrillated after application in concrete mix [%] 38 na 27 Proportion of fibers completely fibrillated after application in concrete mix [%] 62 na 73

[0111] Figures 3 and 4 show photographic representations of concrete slabs reinforced with tested fiber-reinforced materials. The concrete slab in Figure 3 was obtained using the inventive fiber-reinforced material (Ex-2), exhibiting a very good finish without surface defects. Figure 4 shows a concrete slab obtained with reference fiber-reinforced material (Ref-2) after treatment with a hard steel trowel. The surface of this concrete slab has a hairy, “whirling bird” appearance. Petition 870250085663, dated 09 / 22 / 2025, pp. 38 / 46

Claims

1 / 3 CLAIMS 1. Fiber reinforcement material, characterized in that it comprises a plurality of macrosynthetic fibers twisted to form a fiber bundle with a degree of twist of 5 to 100 t / m, preferably 8 to 80 t / m, wherein at least a portion of the macrosynthetic fibers are autofibrillating fibers consisting of two or more partially fused polymeric monofilaments and having a multilobal cross-sectional shape with two or more lobes.

2. Fiber reinforcement material, according to claim 1, characterized in that at least a portion of the macrosynthetic fibers are autofibrillating fibers consisting of three or more partially fused polymeric monofilaments and having a multilobal cross-sectional shape with three or more lobes.

3. Fiber reinforcement material, according to claim 1 or 2, characterized in that the autofibrillating fibers have a linear density of 500 to 10000 den, preferably 800 to 7500 den and / or a length of at least 15 mm, preferably at least 20 mm and / or a length not exceeding 100 mm, preferably not exceeding 85 mm.

4. Fiber reinforcement material, according to any of the preceding claims, characterized in that the autofibrillating fibers are composed of a polymer composition comprising at least 70% by weight, preferably at least 75% by weight, of at least one polypropylene.

5. Fiber reinforcement material, according to claim 4, characterized in that the polymer composition of the autofibrillating fibers further comprises at least 1% by weight, preferably at least 5% by weight, of at least one polyethylene.

6. Fiber reinforcement material, according to any of the preceding claims, characterized in that the ratio of autofibrillating fibers comprises at least 2.5% by weight, more preferably by Petition 870250085663, dated 09 / 22 / 2025, page 39 / 46 2 / 3 less than 5% by weight of the total weight of the macrosynthetic fibers in the fiber bundle.

7. Fiber reinforcement material, according to any of the preceding claims, characterized in that the macrosynthetic fibers are structured on the surface of their outer surfaces, preferably such that a square-mean roughness Rq (λ = 800 pm, 50 times magnification) of the surface is from 1 to 100 pm, preferably 2 to 80 pm, wherein Rq is measured in accordance with ISO 4287:1997.

8. Fiber reinforcement material, according to any of the preceding claims, characterized in that the macrosynthetic fibers have a crimping frequency of 5 to 100 crimps / 100 mm, preferably 15 to 75 crimps / 100 mm and / or a crimping amplitude of 0.1 to 1 mm, preferably 0.5 to 1 mm.

9. Fiber reinforcement material, according to any of the preceding claims, characterized in that at least a portion of the macrosynthetic fibers are autofibrillating fibers having a multilobal cross-sectional shape with three or more lobes and a central section passing axially through the macrosynthetic fiber.

10. Fiber reinforcement material, according to claim 9, characterized in that each lobe has a curved tip portion and a base portion situated towards the central section of the autofibrillating fiber.

11. Fiber reinforcement material, according to claim 10, characterized in that the base portion has a width (D2) that is smaller than the maximum width (D1) of the tip portion.

12. Fiber reinforcement material, according to any of the preceding claims, characterized in that at least a portion of the macrosynthetic fibers are autofibrillating fibers consisting of four partially fused monofilaments.

13. Method for producing a fiber reinforcement material of any of the preceding claims, the method characterized in that it comprises twisting together 2 to 100 macrosynthetic fibers, preferably 5 to 75 macrosynthetic fibers in a twisted bundle using a degree of twist of 5 to 100 t / m, preferably 8 to 80 t / m, wherein at least a portion of the macrosynthetic fibers are autofibrillating fibers consisting of two or more partially fused polymeric monofilaments and having a multilobal cross-sectional shape with two or more lobes.

14. Cementitious material, characterized in that it comprises: a) a binder, b) 0.1 to 3.0% by volume, preferably 0.2 to 2.0% by volume, based on the total volume of the cementitious material, of fiber reinforcement material according to any one of claims 1 to 12, c) Aggregates, d) Water.

15. Method for forming a concrete surface, characterized in that it comprises the steps of: I. Adding fiber-reinforcing material of any of claims 1 to 12 to a fluidized concrete mix under mixer rotation to provide a modified concrete mix, II. Melting the modified concrete mix prepared in step I to provide a molded concrete body, III. Smoothing the surface of the molded concrete body prepared in step II, and IV. Curing the modified concrete mix. Petition 870250085663, dated 09 / 22 / 2025, pp. 41 / 46

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