Polypropylene filament anti-cracking base cloth for asphalt pavement and manufacturing method thereof

Abstract

This application relates to a polypropylene filament anti-cracking base fabric for asphalt pavement and its manufacturing method. The polypropylene filament anti-cracking base fabric for asphalt pavement includes: a base layer; and an elastic needle-punched fiber layer formed by needle punching the base layer, comprising multiple raised units, each of which has a semi-circular arc structure. The open end of each raised unit is located in the base layer. The semi-circular arc raised units form an open microstructure, which has a larger specific surface area and asphalt storage space than planar needle-punched stripes. During asphalt paving, it forms mechanical anchoring, significantly improving asphalt adsorption and bonding strength. The array of multiple raised units is set in the base layer, which can disperse stress through structural deformation under tension or shear, avoiding stress concentration and absorbing base layer stress. After the raised units are combined with asphalt, a continuous and dense waterproof interface can be formed. The asphalt is embedded in the gaps and bottom of the raised units, preventing water seepage at the interface, and effectively blocking rainwater infiltration compared to planar structures.

Description

Technical Field

[0001] This application relates to the technical field of waterproof base fabric manufacturing, and in particular to a polypropylene filament anti-cracking base fabric for asphalt pavement and its manufacturing method. Background Technology

[0002] If road surface cracks are not addressed promptly, rainwater will seep into the roadbed through the cracks. Under the pressure and repeated compression of traffic loads, the fine aggregate and asphalt mixture in the roadbed layer will be eroded and washed away, forming a slurry that seeps out from the cracks – a process known as "slurry pumping." This not only leads to a loosening of the base layer and a decrease in load-bearing capacity, but also, under the cumulative effect of winter freeze-thaw cycles, drastically accelerates the damage to the road structure, significantly shortens its service life, and results in high periodic maintenance costs.

[0003] Current crack treatment technologies have significant limitations: emulsified asphalt crack sealant, due to its material properties, is difficult to penetrate deep into cracks and has a short-term preventive effect; while asphalt pavement anti-crack tape forms a 3-5mm local bulge after sealing, causing bumpy driving, which greatly limits its application in road sections with multiple cracks. Summary of the Invention

[0004] This application provides a polypropylene filament anti-cracking base fabric for asphalt pavement, which effectively resists the stress of subgrade deformation, reduces the generation of pavement cracks, increases the oil absorption performance of the product, forms a waterproof layer, and effectively isolates rainwater from damaging the subgrade.

[0005] This application provides a polypropylene filament anti-cracking base fabric for asphalt pavement, comprising: a base layer; and an elastic needle-punched fiber layer formed by needle punching the base layer, including multiple protruding units, each of the protruding units having a semi-circular arc structure, the open end of each protruding unit penetrating two adjacent fixing points, and the multiple protruding units arranged in an array on the base layer.

[0006] In some optional embodiments, the protruding units in adjacent rows or columns are staggered by a spacing of 1 / 2 to 1 / 3, and the linear units in adjacent rows or columns are arranged vertically.

[0007] In some alternative embodiments, the protruding units in adjacent rows or columns are offset by a 1 / 2 spacing.

[0008] In some alternative embodiments, the protruding units located in the same row or column are arranged at equal intervals.

[0009] In some alternative embodiments, the height, curvature, and cross-sectional shape of each of the protruding units are consistent.

[0010] In some alternative embodiments, the protruding unit with a semi-circular arc structure is U-shaped, Ω-shaped, or C-shaped.

[0011] In some alternative embodiments, the cross-sectional shape of the protruding unit is circular or elliptical.

[0012] On the other hand, this application also provides a manufacturing process for producing the polypropylene filament anti-cracking base fabric for asphalt pavement as described in any of the above claims, comprising the following steps: a melt is formed by molten mixing of polypropylene resin and functional masterbatch using a separating single-screw extruder; the melt is extruded through a spinneret to form a melt stream, which is then stretched by an airflow to form continuous long fibers; a side-blowing cooling method is used to rapidly solidify the continuous long fibers; a fiber separator and an electromagnetic airflow dispersion device are used to achieve uniform web formation of the continuous long fibers; V-shaped needles are arranged crosswise in two perpendicular directions to needle-punch and entangle the fiber web, forming the polypropylene filament anti-cracking base fabric for asphalt pavement; the finished polypropylene filament anti-cracking base fabric for asphalt pavement is wound into rolls by a winding machine.

[0013] This application has at least the following technical advantages over the prior art: This application provides a polypropylene filament anti-cracking base fabric for asphalt pavement, comprising: a base layer; and an elastic needle-punched fiber layer formed by needle punching the base layer, including multiple raised units, each raised unit having a semi-circular arc structure, with the open end of the raised unit located in the base layer. The semi-circular arc raised units form an open microstructure, which has a larger specific surface area and asphalt storage space than planar needle-punched stripes, forming mechanical anchoring during asphalt paving, significantly improving asphalt adsorption and bonding strength. The array of multiple raised units arranged in the base layer can disperse stress through structural deformation under tension or shear, avoiding stress concentration and absorbing base layer stress. After the raised units are combined with asphalt, a continuous and dense waterproof interface can be formed. The asphalt is embedded in the gaps and bottom of the raised units, preventing water seepage at the interface, and effectively blocking rainwater infiltration compared to planar structures. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of a polypropylene filament anti-cracking base fabric for asphalt pavement provided in one embodiment of this application; Figure 2 This is a schematic flowchart illustrating a method for manufacturing a polypropylene filament anti-cracking base fabric for asphalt pavement according to one embodiment of this application.

[0015] Figure labeling: 1-Base layer; 2-Protruding unit. Detailed Implementation

[0016] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0017] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0018] If road surface cracks are not addressed promptly, rainwater will seep into the roadbed through the cracks. Under the pressure and repeated compression of traffic loads, the fine aggregate and asphalt mixture in the roadbed layer will be eroded and washed away, forming a slurry that seeps out from the cracks – a process known as "slurry pumping." This not only leads to a loosening of the base layer and a decrease in load-bearing capacity, but also, under the cumulative effect of winter freeze-thaw cycles, drastically accelerates the damage to the road structure, significantly shortens its service life, and results in high periodic maintenance costs.

[0019] Current crack treatment technologies have significant limitations: emulsified asphalt crack sealant, due to its material properties, is difficult to penetrate deep into cracks and has a short-term preventive effect; while asphalt pavement anti-crack tape forms a 3-5mm local bulge after sealing, causing bumpy driving, which greatly limits its application in road sections with multiple cracks.

[0020] This application provides a polypropylene filament anti-cracking base fabric for asphalt pavements, which effectively resists the stress of subgrade deformation, reduces pavement cracking, increases the product's oil absorption capacity, forms a waterproof layer, and effectively isolates rainwater from damaging the subgrade. The following description refers to the accompanying drawings. Figures 1-2 This paper provides a detailed explanation and description of polypropylene filament anti-cracking base fabric for asphalt pavement.

[0021] This application also provides a polypropylene filament anti-cracking base fabric for asphalt pavement, comprising: a base layer 1; an elastic needle-punched fiber layer formed by needle punching the base layer 1, comprising multiple protruding units 2, each protruding unit 2 having a semi-circular arc structure, the open end of the protruding unit 2 being fixed to the base layer 1, and the multiple protruding units 2 being arranged in an array on the base layer 1.

[0022] Specifically, this application provides a polypropylene filament anti-cracking base fabric for asphalt pavement. The polypropylene filament anti-cracking base fabric for asphalt pavement includes: a base layer 1; and an elastic needle-punched fiber layer formed by needle punching the base layer 1, including multiple raised units 2. Each raised unit 2 has a semi-circular arc structure, and the open end of the raised unit 2 is located in the base layer 1. The semi-circular arc raised unit 2 forms an open microstructure, which has a larger specific surface area and asphalt storage space than planar needle-punched stripes. It forms mechanical anchoring during asphalt paving, significantly improving asphalt adsorption and bonding strength. The array of multiple raised units 2 is arranged in the base layer 1. When subjected to tension or shear, stress can be dispersed through structural deformation to avoid stress concentration and absorb base layer stress. After the raised units 2 are combined with asphalt, a continuous and dense waterproof interface can be formed. The asphalt is embedded in the gaps and bottom of the raised units, preventing water seepage at the interface and effectively blocking rainwater infiltration compared to planar structures.

[0023] In some alternative embodiments, the protruding units 2 in adjacent rows or columns are misaligned by a spacing of 1 / 2 to 1 / 3.

[0024] Specifically, the staggered arrangement makes the raised units 2 staggered rather than neatly aligned on the base fabric surface. When the asphalt is paved and compacted, it is easier to form a continuous and penetrating asphalt binder layer between the raised units 2, reducing the area where the asphalt flow is obstructed, resulting in a more uniform overall adsorption amount and more sufficient local adsorption saturation.

[0025] Furthermore, when raised units 2 are aligned in the same row or column, the asphalt may have straight channels in the longitudinal or transverse directions, weakening the interlocking effect. However, a 1 / 2 to 1 / 3 misalignment creates a tortuous interlocking path for the asphalt in both the horizontal and vertical directions, significantly improving the shear resistance of the surface layer and preventing interface slippage. When raised units 2 are aligned in the same row or column, the weak lines of raised units 2 may be continuously distributed along the row or column direction, easily forming stress concentration zones when base layer cracks propagate. The misaligned arrangement causes the support points of raised units 2 to be staggered, forcibly changing the path of pavement crack propagation, thus blocking or deflecting the cracks and enhancing the overall toughness of the stress.

[0026] In some alternative embodiments, the protrusions 2 in adjacent rows or columns are offset by a 1 / 2 spacing.

[0027] Specifically, the needle punching machine includes two sets of V-shaped needles, which are arranged perpendicularly in two directions. This causes the raised units 2 in adjacent rows or columns to be staggered by a 1 / 2 spacing. If the raised units 2 are formed by the needle punching process, the staggered arrangement corresponds to the staggered arrangement of the needle plate needles, which can avoid weak areas caused by rows and columns of needle marks, and at the same time improve the uniformity of fiber entanglement in the thickness direction. Alignment in the row or column direction may form a continuous groove effect, and rainwater may seep along the grooves under high pressure. The staggered arrangement disrupts this straight channel, further improving the reliability of the waterproof layer.

[0028] In some alternative embodiments, the protruding units 2 located in the same row or column are arranged at equal intervals.

[0029] Specifically, the evenly spaced arrangement ensures consistent gaps between the raised units 2 in the same row or column. During asphalt paving and compaction, the asphalt can evenly fill each gap, avoiding problems such as excessively large gaps leading to asphalt accumulation or insufficient asphalt penetration due to excessively small gaps. The evenly spaced arrangement also allows for precise calculation and control of the number of raised units 2 per unit area and the total gap volume as needed.

[0030] Furthermore, the equidistant arrangement ensures that the support points of the raised units 2 are periodically and uniformly distributed in the same row or column direction. When the base layer 1 is subjected to traffic loads or temperature stress, the stress can be uniformly transmitted along the row or column direction, avoiding local stress concentration caused by uneven spacing. The equidistant spacing of the raised units 2 in the row or column direction ensures the mechanical laws and process controllability in a single direction. The 1 / 2 to 1 / 3 misalignment of the raised units 2 between adjacent rows or columns breaks the weak alignment between multiple rows or columns, realizing multi-directional stress dispersion. This retains the feasibility of the needle punching process while optimizing multi-directional mechanical properties.

[0031] In some alternative embodiments, the height, curvature, and cross-sectional shape of each protrusion unit 2 are consistent.

[0032] Specifically, the height, curvature, and cross-sectional shape of the raised units 2 are consistent, meaning that the void volume formed between each raised unit 2 and the base layer 1 is basically the same. During paving and compaction, the asphalt can evenly fill the space below and around each raised unit 2. When the base layer 1 is subjected to base stress caused by traffic loads or temperature changes, each raised unit 2, as a micro-stress dissipation unit, has similar deformation characteristics, stiffness, and energy absorption capacity due to its consistent structure. The stress can be evenly distributed in the base layer 1, avoiding stress concentration points caused by local structural differences.

[0033] Furthermore, the consistent height, curvature, and cross-sectional shape of each raised unit 2 result in superior technical performance in several dimensions, including uniform asphalt adsorption, consistent stress absorption, stability of the needle punching process, reliability of interfacial bonding, and controllability of product quality for polypropylene filament anti-cracking base fabric used in asphalt pavement.

[0034] In some alternative embodiments, the protruding unit 2 with a semi-circular arc structure is U-shaped, Ω-shaped, or C-shaped.

[0035] Specifically, the U-shaped raised unit 2 has a wide opening, a rounded bottom transition, and relatively straight sidewalls. This provides ample asphalt filling space and good construction adaptability. The large opening of the U-shaped raised unit 2 allows hot asphalt to easily enter the interior and gaps during paving and compaction, reducing the requirements for asphalt fluidity during construction. The relatively straight sidewalls of the U-shaped raised unit 2 create a larger contact area with the asphalt, enhancing interfacial bonding strength.

[0036] The Ω-shaped protrusion unit 2 has a slightly inward opening and a full bottom, which provides strong wrapping and locking ability for asphalt. The arc-shaped bottom and constricted structure of the Ω shape can more effectively disperse stress to both sides when subjected to tension or shear, reducing local stress concentration.

[0037] The C-shaped protrusion unit 2 has a small opening, is semi-closed, and has a distinct internal cavity, forming a closed oil storage cavity. Asphalt is not easily lost, and once it enters, it is not easily squeezed out under high temperature or load, maintaining a long-term asphalt saturation state. The asphalt is protected inside the cavity, reducing contact with air and ultraviolet rays, and delaying asphalt aging.

[0038] In some alternative embodiments, the cross-sectional shape of the protruding unit 2 is circular or elliptical.

[0039] In some alternative embodiments, the substrate 1 is made of polypropylene fiber.

[0040] Specifically, the road base environment is complex; rainwater, de-icing agents, and base materials may be weakly acidic or alkaline. Polypropylene fibers are resistant to chemical corrosion, maintain stable performance over long-term service, and are not easily degraded by corrosion. Polypropylene fibers do not absorb water or hydrolyze; their mechanical properties do not decrease under humid environments or groundwater conditions, ensuring durable waterproofing and crack prevention. Polypropylene has a melting point of approximately 160-170℃ and maintains its structural integrity during asphalt paving at 140-160℃, without melting or shrinking. Both polypropylene fibers and asphalt are hydrocarbon materials, exhibiting good chemical compatibility; asphalt can be uniformly impregnated and firmly adhered, resulting in high interfacial bond strength.

[0041] In some alternative embodiments, the elastic needle-punched fiber layer is made of polypropylene fiber.

[0042] Specifically, the road base environment is complex; rainwater, de-icing agents, and base materials may be weakly acidic or alkaline. Polypropylene fibers are resistant to chemical corrosion, maintain stable performance over long-term service, and are not easily degraded by corrosion. Polypropylene fibers do not absorb water or hydrolyze; their mechanical properties do not decrease under humid environments or groundwater conditions, ensuring durable waterproofing and crack prevention. Polypropylene has a melting point of approximately 160-170℃ and maintains its structural integrity during asphalt paving at 140-160℃, without melting or shrinking. Both polypropylene fibers and asphalt are hydrocarbon materials, exhibiting good chemical compatibility; asphalt can be uniformly impregnated and firmly adhered, resulting in high interfacial bond strength.

[0043] This application also provides a manufacturing process for producing polypropylene filament anti-cracking base fabric for asphalt pavement as mentioned in any of the above, comprising the following steps: a melt is formed by molten mixing of polypropylene resin and functional masterbatch using a separating single-screw extruder; the melt is extruded through a spinneret to form a melt stream, which is then stretched by airflow to form continuous long fibers; a side-blowing cooling method is used to rapidly solidify the continuous long fibers; a fiber separator and an electromagnetic airflow dispersion device are used to achieve uniform web formation of the continuous long fibers; V-shaped needles are arranged crosswise in two perpendicular directions to needle-punch and entangle the fiber web, forming polypropylene filament anti-cracking base fabric for asphalt pavement; the finished polypropylene filament anti-cracking base fabric for asphalt pavement is wound into rolls by a winding machine.

[0044] Specifically, the separate screw comprises a feeding section, a compression mixing section, and a metering section arranged sequentially. The compression mixing section, in particular, employs staggered pin arrangements to reduce melt flow resistance while achieving thorough mixing, ensuring uniform dispersion of the functional masterbatch within the polypropylene matrix and laying the foundation for consistent fiber mechanical properties. The metering section features a reduced screw diameter of 0.9 mm and a shallower screw channel depth of 2.5–3 mm, stabilizing pressure and temperature and preventing melt fluctuations from affecting spinning stability.

[0045] The melt is extruded through a spinneret to form a melt stream, which is then drawn into continuous long fibers by airflow. The spinneret includes a spinneret orifice with a diameter of 0.58–0.65 mm, an aspect ratio of 4–5, and a convergence angle of 50–60°. This design effectively suppresses melt outlet expansion, avoids fiber surface roughness, and improves fiber mechanical properties.

[0046] A side-blowing cooling method is employed to rapidly solidify continuous long fibers. The side-blowing airflow causes the fibers to cool and solidify quickly after leaving the spinneret, fixing the molecular orientation structure and preventing fiber structure relaxation and performance degradation caused by natural cooling. The uniform side-blowing airflow maintains appropriate spacing between fibers, preventing incompletely solidified fibers from sticking together and forming tangled strands, thus ensuring monofilament separability. Sufficiently cooled fibers are less prone to deformation and sticking during subsequent filament separation and web formation, providing a prerequisite for uniform web formation.

[0047] By using a fiber separator and an electromagnetic airflow dispersion device, uniform web formation of continuous long fibers is achieved. The maximum diameter of the fiber separator outlet is twice the diameter of the drawing tube. By adjusting the current and the drawing airflow pressure, the gap at the drawing tube outlet is controlled, making the fiber movement direction controllable and greatly improving the problem of fiber bundling. Due to the increased volume at the drawing tube outlet and the reduced drawing airflow velocity, the fibers are evenly and randomly distributed on the web forming curtain, avoiding weight fluctuations and mechanical property dispersions caused by uneven web formation.

[0048] Using V-shaped needles arranged in two perpendicular directions, the fiber web is needle-punched and entangled to form a polypropylene filament anti-cracking base fabric for asphalt pavement. The V-shaped needles are arranged in two perpendicular directions, and by controlling the needle depth and the arrangement of the needle plates, an array of raised units 2 are formed on the fabric surface. The V-shaped needles have a stronger ability to hook and migrate fibers during the puncture process. Combined with the vertical cross arrangement, the fibers form an efficient entanglement network in both the thickness direction and the in-plane direction, which significantly improves tensile strength, bursting strength and tearing strength.

[0049] The finished polypropylene filament anti-cracking base fabric for asphalt pavement is wound into rolls by a winding machine. The width of the base fabric produced by this process can be flexibly adjusted according to the road width, reducing on-site overlapping treatment and improving construction efficiency and waterproof continuity.

[0050] In this application, the term "multiple" refers to at least two or more, unless otherwise expressly defined. The terms "installed," "connected," "linked," and "fixed," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "linked" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0051] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

Claims

1. A polypropylene filament anti-cracking base fabric for asphalt pavement, characterized in that, include: Basal layer (1); The elastic needle-punched fiber layer is formed by needle punching the base layer (1) using a needle punching machine. It includes multiple protruding units (2), each of the protruding units (2) having a semi-circular arc structure. The open end of the protruding unit (2) is fixed to the base layer (1), and the multiple protruding units (2) are arranged in an array on the base layer (1).

2. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 1, characterized in that, The protruding units (2) in adjacent rows or columns are misaligned by a spacing of 1 / 2 to 1 / 3.

3. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 1, characterized in that, The protruding units (2) in adjacent rows or columns are misaligned by a 1 / 2 spacing.

4. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 3, characterized in that, The raised units (2) located in the same row or column are arranged at equal intervals.

5. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 4, characterized in that, The height, curvature and cross-sectional shape of each of the protruding units (2) are consistent.

6. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 5, characterized in that, The protruding unit (2) with a semi-circular arc structure is U-shaped, Ω-shaped, or C-shaped.

7. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 6, characterized in that, The cross-sectional shape of the protruding unit (2) is circular or elliptical.

8. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 7, characterized in that, The base layer (1) is made of polypropylene fiber.

9. The polypropylene filament anti-cracking base fabric for asphalt pavement according to claim 8, characterized in that, The elastic needle-punched fiber layer is made of polypropylene fiber.

10. A manufacturing process, characterized in that, The method for producing the polypropylene filament anti-cracking base fabric for asphalt pavement as described in any one of claims 1-9 includes the following steps: A melt of polypropylene resin and functional masterbatch melted together using a separate single-screw extruder; The melt is extruded through a spinneret to form a melt stream, which is then drawn into continuous long fibers by airflow. Side-blowing cooling method is used to rapidly solidify continuous long fibers; Uniform web formation of continuous long fibers is achieved through a fiber splitter and an electromagnetic airflow dispersion device. V-shaped needles are arranged in two perpendicular directions to needle and entangle the fiber network, forming a polypropylene filament anti-cracking base fabric for asphalt pavement. The finished polypropylene filament anti-cracking base fabric for asphalt pavement is wound into rolls by a winding machine.

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