Special grooved fiber for anti-cracking and toughening of grouting material and preparation method of special grooved fiber and grouting material

Abstract

A special notched fiber for crack resistance and toughening of grouting materials, its preparation method, and the grouting material itself are disclosed. The notched fiber comprises a fiber matrix of regenerated protein fiber, the surface of which is provided with periodic notches, and the fiber surface is covered with a gelatin-chitosan-nano silica composite coating. This invention, by designing notches of specific geometric shapes on the fiber surface and introducing regenerated protein fiber from the textile field and a gelatin-based composite coating from the biomedical field as non-field materials, forms a synergistic toughening mechanism of "mechanical anchoring + chemical bonding." Test results show that the notched fiber of this invention improves the crack resistance of the grouting material by 40%-45%, increases toughness by 50%-55%, and improves dispersibility by more than 30%, solving the problems of easy clumping and poor workability of traditional fibers. Compared with existing patented technologies, this invention represents a significant advancement in interfacial bonding strength, crack resistance and toughening efficiency, and long-term durability.

Description

Technical Field

[0001] This invention relates to a special scoring fiber for crack resistance and toughening of grouting materials and its preparation method, belonging to the field of building materials technology. Background Technology

[0002] Grouting materials, widely used in structural reinforcement, infrastructure repair, and cultural heritage preservation, have long suffered from brittleness and cracking issues that have remained unresolved. Fiber reinforcement is the mainstream technology for improving the crack resistance of grouting materials, but existing technologies have several limitations:

[0003] 1. The synergistic effect of fiber-reinforced materials and composite admixtures (water-reducing agents, expansion agents, waterproofing agents, and stabilizers) inhibits shrinkage cracking. Limitations: It relies on the chemical admixtures rather than the structural design of the fiber itself; the interfacial bonding between the fiber and the matrix is ​​still mainly physical adsorption; long-term performance is unstable; and the fiber dispersion problem has not been solved.

[0004] 2. Composite fibers (40-125 parts) are combined with expanding agents, fly ash and other components to reduce the risk of temperature cracks and shrinkage cracks. Limitations: large amount of fiber is used, resulting in high cost; the bonding between the fiber and the matrix still depends on the surface chemical properties and does not involve fiber morphology optimization; it is prone to clumping, which affects workability.

[0005] 3. PVA fibers are prepared through copolymerization and surface modification to construct multi-layer cement boards. Limitations: The process is complex and requires multiple modifications and layering. PVA fibers have poor dispersibility in the cement matrix, especially at higher dosages.

[0006] 4. A three-dimensional interlocking network structure for crack prevention is formed using a quaternary fiber system (polypropylene, polyethylene, basalt fiber, and cellulose fiber). Limitations: The process of compounding multiple fibers is complex; the interfacial bonding force is still limited; and the fiber dispersion problem remains unsolved.

[0007] In summary, existing fiber-reinforced technologies for improving the crack resistance of grouts still have drawbacks such as unstable long-term interfacial bonding between fibers and the matrix and poor dispersibility. Summary of the Invention

[0008] To address the issues of poor long-term performance and dispersibility in existing technologies, this invention provides a special notched fiber for crack resistance and toughening of grouting materials, a method for preparing the same, and a grouting material using the notched fiber.

[0009] The technical solution of the present invention is as follows:

[0010] A special scoring fiber for crack resistance and toughening of grouting material includes a fiber matrix of regenerated protein fiber, the surface of which is provided with periodic scoring, and the surface of which is covered with a gelatin-chitosan-nano silica composite coating.

[0011] Preferably, the depth of the groove is 10%-30% of the diameter of the fiber matrix, and the spacing is 50-200μm; the shape of the groove is wavy, annular, or spiral.

[0012] Preferably, the regenerated protein fiber is derived from textile waste and activated by alkali treatment.

[0013] Preferably, the thickness of the gelatin-chitosan-nano silica composite coating is 1-3 μm.

[0014] The aforementioned method for preparing a special scoring fiber for crack resistance and toughening of grouting materials includes the following steps:

[0015] The fiber matrix is ​​scored;

[0016] Preparation of gelatin-chitosan-nano silica composite sol;

[0017] The scoring fibers are impregnated with a composite sol, and the coating thickness is controlled by a dip-coating method.

[0018] Crosslinking and curing at 50-60℃;

[0019] The regenerated protein fibers are treated with alkali.

[0020] Preferably, the markings are formed on the surface of the fiber matrix by laser engraving or mechanical embossing, creating periodic markings with a depth of 10%-30% of the fiber diameter and a spacing of 50-200 μm. The laser engraving parameters are: power 50-100W, scanning speed 100-500 mm / s.

[0021] Preferably, gelatin, chitosan and nano-silica are dissolved in an aqueous solution of acetic acid with a concentration of 3-7% at a mass ratio of 3:0.8-1.2:0.8-1.2, and mechanically stirred at a speed of 200-300 rpm for 30 minutes in a water bath at 40-50℃ to form a homogeneous and stable composite sol.

[0022] Preferably, the impregnation involves immersing the scored fibers in a composite sol for 60-120 seconds to ensure the fibers are fully wetted. The coating thickness is controlled by the pull-up method, with the pull-up speed controlled at 0.5-2 mm / s during coating. By precisely controlling the pull-up speed and sol viscosity, a uniform coating with a thickness of 1-3 μm is obtained.

[0023] Preferably, the alkaline treatment conditions for the regenerated protein fiber are as follows: the regenerated protein fiber is placed in a 5% NaOH solution and treated at 60°C for 2 hours to expose the active amino and carboxyl groups on its fiber surface and enhance its chemical bonding ability with the grout matrix.

[0024] A grouting material comprising the aforementioned notched fibers, wherein the amount of the notched fibers is 0.3%-1.0% of the total mass of the grouting material.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention relates to a notched fiber specifically designed for crack resistance and toughening of grouting materials, and its preparation method, belonging to the field of building materials technology. Addressing the problems of insufficient fiber-matrix interfacial bonding strength, poor dispersibility, and limited toughening effect in existing concrete crack-resistant fibers, this invention designs notches of specific geometric shapes on the fiber surface and introduces a cross-disciplinary material, recycled protein fiber, and a gelatin-based composite coating, forming a synergistic toughening mechanism of "mechanical anchoring + chemical bonding." Test results show that the notched fiber of this invention improves the crack resistance of grouting materials by 40%-45%, increases toughness by 50%-55%, and improves dispersibility by more than 30%, solving the problems of easy clumping and poor workability of traditional fibers. Compared with existing technologies, this invention represents a significant advancement in interfacial bonding strength, crack resistance and toughening efficiency, and long-term durability.

[0027] Specifically, this invention breaks through traditional thinking by addressing the issue from two dimensions: fiber surface structure design and cross-disciplinary material applications.

[0028] 1. Structural design: Periodic grooves are introduced on the fiber surface to enhance the interfacial bonding force through mechanical anchoring effect.

[0029] 2. Materials Innovation:

[0030] Regenerated protein fiber: derived from textile industry waste (such as wool / silk), after being activated by alkali treatment, exposing active groups, which can react with cement matrix to form CSH gel.

[0031] Gelatin-based composite coating: composed of gelatin, chitosan and nano-silica, forming a flexible-rigid synergistic structure to enhance chemical adhesion.

[0032] 3. Synergistic mechanism: The notched structure deflects and bifurcates the crack propagation path, improving crack resistance and providing mechanical anchoring; the gelatin coating enhances chemical bonding, absorbs energy, and improves fiber pull-out work; the protein fiber reacts with cement hydration products to generate CSH gel, reducing permeability and promoting microstructure densification. The three work synergistically to produce an unexpected crack resistance and toughening effect of "1+1+1>3". Detailed Implementation

[0033] To better understand the present invention, specific descriptions are provided below through embodiments. It should be noted that the following embodiments are for further illustration only and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention still fall within the scope of protection of the present invention.

[0034] In addition, unless otherwise stated, all raw materials used are commercially available.

[0035] The preparation methods for the following embodiments are as follows:

[0036] 1. Fiber activation:

[0037] The regenerated protein fibers were treated with alkali (5% NaOH solution, 60℃, 2h) to expose the active amino and carboxyl groups on the fiber surface, thereby enhancing their chemical bonding ability with the grout matrix.

[0038] 2. Scratching:

[0039] The regenerated protein fibers are marked by laser engraving or mechanical embossing.

[0040] Process parameters: laser power 50-100W, scanning speed 100-500mm / s.

[0041] 3. Preparation of composite sol:

[0042] Gelatin, chitosan, and nano-silica are dissolved in an acetic acid solution (concentration 5%) to form a composite sol.

[0043] 4. Coating preparation:

[0044] The scoring fibers are impregnated in a composite sol, and the coating thickness (1-3 μm) is controlled by the dip-coating method.

[0045] 5. Cross-linking and curing:

[0046] Cross-linking and curing: The coated fibers are placed in an oven at 50-60℃ for 30-60 minutes for heat treatment to complete curing. During this process, the amino groups on the gelatin molecular chain and the hydroxyl groups and some amino groups on the chitosan molecular chain undergo intermolecular cross-linking to form a stable three-dimensional network structure. At the same time, the nano-silica particles, as inorganic fillers, have silanol groups on their surface that interact strongly with the polar groups in the gelatin-chitosan organic network, uniformly dispersed and anchored in the network. This achieves a synergistic effect of enhanced flexibility in the organic phase and increased rigidity in the inorganic phase, significantly improving the mechanical properties and durability of the coating.

[0047] Example 1

[0048] This embodiment describes the preparation and application of notched wool protein fibers.

[0049] Matrix fiber: Wool protein fiber extracted from textile waste, with an average diameter of 25 μm. This fiber has natural hydrophilicity and abundant active groups.

[0050] Alkali pretreatment: First, treat the fiber with 5% NaOH solution at 60°C for 2 hours to remove surface impurities and expose more amino and carboxyl active sites.

[0051] Scribing process: Mechanical embossing is used to create ring-shaped scribing patterns with a depth of approximately 6μm and a spacing of 120μm on the surface of the activated wool fibers. Due to the toughness of protein fibers, mechanical embossing is more effective than laser engraving in preventing fiber burns and embrittlement.

[0052] Coating preparation and curing: The coating is immersed in a gelatin-chitosan-nano silica composite sol (mass ratio 3:1:1) for 120 seconds, with the lifting speed controlled at 1 mm / s, to form a uniform composite coating with a thickness of about 2 μm, and then crosslinked and cured at 55℃.

[0053] Application test: Added to cement-based grout at a volume ratio of 0.5%. Test results show:

[0054] Crack resistance: Compared with the baseline group without fiber, early shrinkage cracks were reduced by 44% at 28 days.

[0055] Enhanced toughness: The fiber pull-out work increased by 58%, demonstrating excellent toughening effect.

[0056] Interface bonding: Microscopic observation revealed that the indentations on the fiber surface provided effective mechanical anchoring, and the gelatin coating formed a good chemical bond with cement hydration products and the fiber itself.

[0057] Dispersibility: The fibers are evenly dispersed in the slurry without clumping, and the clumping rate is <3%.

[0058] Example 2

[0059] Raw material: wool / silk protein fibers extracted from textile waste.

[0060] Activation treatment: Treat with 5% NaOH solution (60℃, 2h).

[0061] Scratching: Mechanical embossing creates wavy scratches with a depth of 15μm and a spacing of 150μm.

[0062] Coating treatment and curing: Gelatin-chitosan-nano silica composite coating (mass ratio 3:1:1), coating thickness 2μm, then cured.

[0063] Application testing: When applied to grouting materials for grout protection, compatibility is improved by 30% and impermeability is increased by 25%.

[0064] Comparative Example 1: Traditional silane-treated fibers (corresponding to CN117985973).

[0065] The silane-treated fibers described in CN117985973 were added to the same grout at a dosage of 0.5%.

[0066] Test results: Crack resistance increased by 25%, toughness increased by 30%, and clumping rate increased by 12%.

[0067] Comparative Example 2: PVA fiber reinforced cement board (corresponding to CN119773030).

[0068] PVA fibers as described in CN119773030 are used, with a dosage of 1.0% in the same grouting material.

[0069] Test results: Crack resistance increased by 22%, toughness increased by 28%, and clumping rate increased by 18%.

[0070] Comparative Example 3: Quaternary fiber system (corresponding to CN120681998).

[0071] The quaternary fiber system (polypropylene, steel fiber, basalt fiber, carbon fiber) described in CN120681998 was adopted, with a total doping amount of 1.5%.

[0072] Test results: Crack resistance increased by 38%, toughness increased by 42%, and clumping rate decreased by 8%.

[0073] Comparative Example 4: Basalt fiber reinforced grout.

[0074] Basalt fiber (12mm in length and 20μm in diameter) was added at a dosage of 0.8% to the same grouting material.

[0075] Test results: Crack resistance increased by 32%, toughness increased by 36%, and clumping rate decreased by 13%.

[0076] The experimental results are compared in Table 1.

[0077] Table 1: Performance Comparison of Fibers from the Embodiments of the Present Invention with Existing Patented Fibers

[0078]

[0079] Through the above comparative experiments, the present invention has the following advantages over the prior art:

[0080] 1. Breakthrough in interface bonding strength:

[0081] Traditional fibers (such as Comparative Examples 1 and 2) mainly rely on chemical bonding or physical adsorption, resulting in limited interfacial bonding.

[0082] The notched structure of this invention provides a mechanical anchoring effect, which, combined with the chemical bonding of the gelatin coating, increases the interfacial bonding strength by more than 50%.

[0083] 2. Significant improvement in dispersion:

[0084] Existing fiber technologies (such as Comparative Examples 2 and 4) have significant shortcomings in terms of dispersibility, with a clumping rate as high as 13%-18%.

[0085] The notched structure of this invention reduces the van der Waals forces between fibers, lowering the clumping rate to below 5% and significantly improving workability.

[0086] 3. Synergistic toughening effect:

[0087] Although the quaternary fiber system (Comparative Example 3) can achieve relatively good toughening effect, the process is complicated and the cost is high.

[0088] This invention achieves superior toughening effect through the multifunctional design of a single fiber, and the process is simple and inexpensive.

[0089] 4. Innovative applications of cross-disciplinary materials:

[0090] Existing technologies are mostly limited to traditional building materials, such as steel fiber, polypropylene fiber, and PVA fiber.

[0091] This invention introduces cross-disciplinary materials such as regenerated protein fibers and gelatin-based coatings, forming a unique "flexible-rigid" synergistic structure in the grouting material, resulting in unexpected crack resistance and toughening effects.

[0092] in conclusion:

[0093] This invention successfully solves the problems of weak interfacial bonding, poor dispersibility, and limited toughening in existing concrete crack-resistant fiber technologies through a notched structure design and the application of non-interfacial materials. Compared with the prior art, this invention has the following outstanding advantages:

[0094] 1. Excellent performance: Significantly improved crack resistance and toughness (40%-45% and 50%-55% respectively), and excellent dispersibility (agglomeration rate <5%).

[0095] 2. Low cost: It utilizes textile waste, making it both environmentally friendly and economical.

[0096] 3. Broad application prospects: Applicable to high-requirement fields such as structural reinforcement, cultural heritage protection, and tunnel engineering.

[0097] Experimental data confirm that the present invention is superior to existing technologies in terms of crack resistance, toughness, dispersibility, and durability, and has significant technological advancements and commercialization potential.

[0098] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or equivalent modifications to the above-disclosed technical content. However, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A special-purpose notch fiber for anti-cracking and toughening of grouting material, characterized in that, The fiber matrix includes regenerated protein fibers, the surface of which is provided with periodic grooves and is covered with a gelatin-chitosan-nano silica composite coating.

2. The scored fiber of claim 1, wherein, The depth of the scribing is 10%-30% of the diameter of the fiber matrix, and the spacing between the scribing marks is 50-200μm; the shape of the scribing marks is wavy, circular, or spiral.

3. The scored fiber of claim 1, wherein, The regenerated protein fiber is derived from textile waste and activated through alkali treatment.

4. The scored fiber of claim 1, wherein, The thickness of the gelatin-chitosan-nano silica composite coating is 1-3 μm.

5. A method for preparing a special scoring fiber for crack resistance and toughening of grouting material according to any one of claims 1-4, characterized in that, Includes the following steps: The fiber matrix is ​​scored; Preparation of gelatin-chitosan-nano silica composite sol; The scoring fibers are impregnated with a composite sol, and the coating thickness is controlled by a dip-coating method. Crosslinking and curing occurs at 50-60℃.

6. The method of claim 5, wherein, The engraving is achieved by laser engraving or mechanical embossing. The laser power for laser engraving is 50-100W, and the scanning speed is 100-500mm / s.

7. The method of claim 5, wherein, Gelatin, chitosan, and nano-silica were dissolved in an aqueous solution of acetic acid with a mass ratio of 3:0.8-1.2:0.8-1.2 at a concentration of 3-7%. The solution was mechanically stirred at 200-300 rpm for 30 minutes in a water bath at 40-50°C to form a homogeneous and stable composite sol.

8. The method of claim 5, wherein, The impregnation process involves immersing the etched fibers in a composite sol for 60-120 seconds. The coating thickness is controlled by the lifting method, where the lifting speed is controlled at 0.5-2 mm / s during coating to obtain a uniform coating with a thickness of 1-3 μm.

9. The method of claim 5, wherein, It also includes alkali pretreatment of the regenerated protein fibers.

10. A grout, characterized in that, It contains the notched fiber as described in any one of claims 1-5, with an admixture amount of 0.3%-1.0% of the total mass of the grout.

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