Modified plant fiber, plant fiber cement product and preparation method thereof

Abstract

The invention provides a modified plant fiber, a plant fiber cement product and a preparation method thereof, and relates to the technical field of cement preparation. The modified plant fiber is prepared from the following components in parts by mass: 5 to 10 parts of plant straw, 50 to 100 parts of hydrogen peroxide solution, 41.7 to 200 parts of acrylic acid solution, 0.025 to 0.25 part of initiator, 0.2 to 0.64 part of cross-linking agent and 50 to 70 parts of deionized water. Lignin and hemicellulose in plant fibers are removed by hydrogen peroxide, and then acrylic acid is grafted to cellulose through a solution polymerization method, so that the plant fibers have internal curing capacity. The modified plant fiber disclosed by the invention continuously releases water in a cement hydration process, so that the self-constriction and cracking risks are reduced, pores are reduced, and interface adhesion is improved; meanwhile, the silane coupling agent is introduced, so that the interface bonding between the fiber and the matrix is enhanced, and the crack resistance and durability are improved.

Description

Technical Field

[0001] This invention relates to the field of cement preparation technology, and in particular to a modified plant fiber, plant fiber cement products, and a method for preparing the same. Background Technology

[0002] With the deepening of green building and sustainable development concepts, plant fibers, as a widely available and renewable natural material, are receiving increasing attention in the building materials field. Plant straw, due to its lightweight, biodegradable, and low-cost characteristics, is being explored for use in cement-based composite materials to partially replace traditional reinforcing materials (such as synthetic fibers and asbestos), thereby reducing environmental impact and improving the comprehensive utilization efficiency of resources.

[0003] However, the application of natural plant fibers in cementitious matrices still faces many challenges. On the one hand, components such as hemicellulose and pectin in plant fibers are easily decomposed in alkaline cement environments, leading to decreased fiber strength and insufficient durability. On the other hand, plant fibers contain a large number of hydroxyl groups on their surface, exhibiting strong hydrophilicity and poor compatibility with the hydrophobic cement matrix interface, easily forming weak interfaces and affecting the mechanical properties of the composite material. Furthermore, impurities such as soluble sugars in plant fibers may inhibit the cement hydration process, further reducing the early strength of the product.

[0004] To improve the compatibility of plant fibers with cement, existing research mainly employs physical or chemical methods to modify the fibers. Common modification techniques include alkali treatment, acetylation, and silane coupling agent treatment, aiming to remove impurities from the fiber surface, reduce hydrophilicity, and enhance interfacial bonding. However, these methods often have limited processing efficiency, unstable modification effects, or introduce secondary pollution, making it difficult to meet the needs of practical engineering applications.

[0005] Therefore, there is an urgent need to develop a plant fiber modification method that is highly efficient, has stable processing, and is environmentally compatible, and to effectively apply it to cement-based composite materials to improve the overall performance of the composite materials. Summary of the Invention

[0006] In view of this, the present invention proposes a modified plant fiber, a plant fiber cement product and its preparation method, which not only improves the fiber dispersion and compatibility, but also enhances the crack resistance, density and long-term durability of the cement composite material, providing a new path for the development of green functional cement-based materials.

[0007] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a modified plant fiber, comprising, by weight parts: 5-10 parts of plant straw, 50-100 parts of hydrogen peroxide solution, 41.7-200 parts of acrylic acid solution, 0.025-0.25 parts of initiator, 0.2-0.64 parts of crosslinking agent, and 50-70 parts of deionized water.

[0008] Furthermore, the plant straw includes, but is not limited to, one or more of corn stalks, sugarcane bagasse, rice straw, and rice husks.

[0009] Furthermore, the hydrogen peroxide solution has a mass concentration of 10-15 wt%, and the acrylic acid solution has a neutralization degree of 0.5-0.7 and a mass concentration of 40-60 wt%.

[0010] Furthermore, the acrylic acid solution is composed of 25-80 parts acrylic acid, 6.9-31.08 parts sodium hydroxide, and 7-97.8 parts deionized water.

[0011] Secondly, the present invention relates to a method for preparing the above-mentioned modified plant fibers, comprising the following steps: S1. The pretreated plant straw is crushed and sieved to obtain plant fiber raw material; S2. After oxidizing the plant fiber raw material with hydrogen peroxide solution, acrylic acid solution, initiator, crosslinking agent and deionized water are added, and the mixture is heated and kept warm in a water bath under nitrogen protection to obtain pretreated fiber. S3. Clean and dry the pretreated fibers to obtain modified plant fibers.

[0012] Thirdly, the present invention relates to the application of the above-mentioned modified plant fibers in the preparation of plant fiber cement products.

[0013] Fourthly, the present invention provides a plant fiber cement product, comprising, by weight, 5-10 parts of the modified plant fiber as described in any one of claims 1-5; and further comprising: 30 parts of silicate cement, 60-70 parts of sand, 0.5-2 parts of silane coupling agent, and 20-25 parts of water.

[0014] Furthermore, the silicate cement is selected from one of P·O 42.5, P·O 52.5, and P·C 42.5, and the sand has a particle size of 0.3-0.5 mm.

[0015] Furthermore, the silane coupling agent includes, but is not limited to, one or more of aminosilane KH-550, epoxysilane KH-560, and acrylate silane KH570.

[0016] Fifthly, the present invention also relates to a method for preparing the above-mentioned plant fiber cement product, comprising the following steps: A1. Prepare raw materials according to the stated mass proportions, and mix the modified plant fiber with water and the silicate cement with sand respectively. A2. Add the modified plant fiber and water mixture to the mixture of silicate cement and sand, stir, then add the silane coupling agent and continue stirring; A3. Curing the mixture yields plant fiber cement products.

[0017] The present invention provides a modified plant fiber, a plant fiber cement product, and a method for preparing the same, which have the following advantages over the prior art: (1) This invention utilizes hydrogen peroxide to treat plant fibers, effectively removing lignin and some hemicellulose from the plant fibers; and uses solution polymerization to modify the cellulose in the treated plant straw fibers and bridge acrylic acid, so that the plant fiber cement products have self-curing properties, which can effectively improve the shortcomings of drying shrinkage of plant fiber cement products.

[0018] (2) The modified plant fiber of the present invention acts like a "reservoir" during cement curing, continuously providing the water required for hydration, achieving an internal curing effect, promoting hydration inside the cement, reducing the risk of self-shrinkage and cracking during early hydration, reducing the voids inside the plant fiber cement product, and making the interfacial bonding between the fiber and the cement paste tighter, thereby improving the crack resistance and durability of the plant fiber cement product. At the same time, the introduction of a silane coupling agent to construct a strong chemical coating layer between the fiber and the cement matrix further enhances the interfacial bonding strength and the long-term durability of the composite material.

[0019] (3) The preparation process of this invention is simple and the conditions are mild, making it easy to scale up for industrial application. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0022] Preparation Example 1 This preparation example provides a modified plant fiber, which, by mass parts, comprises the following components: 5 parts corn stalks, 50 parts 10wt% hydrogen peroxide solution, 41.7 parts 60wt% acrylic acid solution, 0.05 parts potassium persulfate (initiator), 0.025 parts N,N'-methylenebisacrylamide (crosslinking agent), and 50 parts deionized water. The acrylic solution is composed of 25 parts acrylic acid, 9.7 parts sodium hydroxide, and 7 parts water, with a neutralization degree of 0.7.

[0023] This modified plant fiber is prepared through the following steps: S1. After washing, drying and crushing the corn stalks, pass them through a 10-mesh sieve to obtain plant fiber raw materials. S2. Plant fiber raw material is added to a 10wt% hydrogen peroxide solution with a neutral pH value and stirred in a water bath at 50°C for 2.5h. Then, 60wt% acrylic acid solution, potassium persulfate, N,N'-methylenebisacrylamide and deionized water are added. Under nitrogen protection, the mixture is stirred and prepolymerized in a water bath at 70°C and then heated to 90°C and kept at that temperature for 2h to obtain pretreated fiber. S3. Rinse and dry the pretreated fiber with 95% ethanol to obtain modified plant fiber.

[0024] Preparation Example 2 This preparation example provides a modified plant fiber, which, by mass parts, comprises the following components: 10 parts sugarcane bagasse, 100 parts 15wt% hydrogen peroxide solution, 100 parts 40wt% acrylic acid solution, 0.32 parts ammonium persulfate (initiator), 0.12 parts N,N'-methylenebisacrylamide (crosslinking agent), and 70 parts deionized water. The acrylic solution is composed of 40 parts acrylic acid, 15.54 parts sodium hydroxide, and 44.46 parts water, with a neutralization degree of 0.7.

[0025] This modified plant fiber is prepared through the following steps: S1. Wash, dry and crush the sugarcane bagasse, and then pass it through a 10-mesh sieve to obtain plant fiber raw material. S2. Plant fiber raw materials are added to a 15wt% hydrogen peroxide solution with a neutral pH value and stirred in a water bath at 60°C for 2.5h. Then, 40wt% acrylic acid solution, potassium persulfate, N,N'-methylenebisacrylamide and deionized water are added. Under nitrogen protection, the mixture is stirred and prepolymerized in a water bath at 75°C and then heated to 90°C and kept at that temperature for 0.5h to obtain pretreated fibers. S3. Rinse and dry the pretreated fiber with 95% ethanol to obtain modified plant fiber.

[0026] Preparation Example 3 This preparation example provides a modified plant fiber, which, by mass parts, comprises the following components: 10 parts of rice straw, 75 parts of 12.5 wt% hydrogen peroxide solution, 120 parts of 50 wt% acrylic acid solution, 0.3 parts of potassium persulfate (initiator), 0.12 parts of N,N'-methylenebisacrylamide (crosslinking agent), and 60 parts of deionized water. The acrylic solution is composed of 60 parts acrylic acid, 19.98 parts sodium hydroxide, and 40.02 parts water, with a neutralization degree of 0.6.

[0027] This modified plant fiber is prepared through the following steps: S1. After washing, drying and crushing the rice straw, pass it through a 10-mesh sieve to obtain plant fiber raw material; S2. Plant fiber raw materials are added to a 12.5 wt% hydrogen peroxide solution with a neutral pH value and stirred in a water bath at 60°C for 2.5 h. Then, 50 wt% acrylic acid solution, potassium persulfate, N,N'-methylenebisacrylamide and deionized water are added. Under nitrogen protection, the mixture is stirred and prepolymerized in a water bath at 75°C and then heated to 90°C and kept at that temperature for 1 h to obtain pretreated fibers. S3. Rinse and dry the pretreated fiber with 95% ethanol to obtain modified plant fiber.

[0028] Preparation Example 4 This preparation example provides a modified plant fiber, which, by mass parts, comprises the following components: 10 parts rice husk, 100 parts 10wt% hydrogen peroxide solution, 100 parts 50wt% acrylic acid solution, 0.1 parts ammonium persulfate (initiator), 0.05 parts N,N'-methylenebisacrylamide (crosslinking agent), and 70 parts deionized water. The acrylic solution is composed of 50 parts acrylic acid, 13.875 parts sodium hydroxide, and 36.125 parts water, with a neutralization degree of 0.5.

[0029] This modified plant fiber is prepared through the following steps: S1. After washing, drying and crushing the rice husks, pass them through a 10-mesh sieve to obtain plant fiber raw materials. S2. Plant fiber raw materials are added to a 10wt% hydrogen peroxide solution with a neutral pH value and stirred in a water bath at 50°C for 1 hour. Then, 50wt% acrylic acid solution, potassium persulfate, N,N'-methylenebisacrylamide and deionized water are added. Under nitrogen protection, the mixture is stirred and prepolymerized in a water bath at 70°C and then heated to 90°C and kept at that temperature for 2 hours to obtain pretreated fibers. S3. Rinse and dry the pretreated fiber with 95% ethanol to obtain modified plant fiber.

[0030] Preparation Example 5 This preparation example provides a modified plant fiber, which, by mass parts, comprises the following components: 10 parts of corn stalks and sugarcane bagasse (mass ratio 1:1), 50 parts of 15wt% hydrogen peroxide solution, 200 parts of 40wt% acrylic acid solution, 0.04 parts of potassium persulfate (initiator), 0.24 parts of N,N'-methylenebisacrylamide (crosslinking agent), and 60 parts of deionized water; The acrylic solution is composed of 80 parts acrylic acid, 22.2 parts sodium hydroxide, and 97.8 parts water, with a neutralization degree of 0.5.

[0031] This modified plant fiber is prepared through the following steps: S1. After washing, drying and crushing the corn stalks and sugarcane bagasse, pass them through a 10-mesh sieve to obtain plant fiber raw materials. S2. Plant fiber raw material is added to a 15wt% hydrogen peroxide solution with a neutral pH value and stirred in a water bath at 50°C for 2 hours. Then, 40wt% acrylic acid solution, potassium persulfate, N,N'-methylenebisacrylamide and deionized water are added. Under nitrogen protection, the mixture is stirred and prepolymerized in a water bath at 75°C and then heated to 90°C and kept at that temperature for 2 hours to obtain pretreated fiber. S3. Rinse and dry the pretreated fiber with 95% ethanol to obtain modified plant fiber.

[0032] Preparation of Comparative Example 1 The difference from Preparation Example 1 is that it does not contain hydrogen peroxide solution, the steps are adapted, and the rest remain unchanged.

[0033] Preparation of Comparative Example 2 The difference from Preparation Example 1 is that the corn stalks were placed directly into 50 parts of a 10 wt% sodium hydroxide solution, stirred at 60°C for 2 hours, then rinsed with 95% ethanol and dried to obtain modified plant fiber.

[0034] The water absorption properties of the modified plant fibers prepared in Preparation Examples 1-5 and Comparative Examples 1-2 were determined according to GB / T 20405.5-2025. The results are shown in Table 1.

[0035] Table 1 Water absorption performance results Based on Preparation Examples 1-4, Comparative Preparation Example 1, and Table 1, it can be seen that alkaline or neutral hydrogen peroxide solutions can remove or loosen the lignin coated on the surface of cellulose, dissolve some hemicellulose, expose more cellulose hydroxyl groups, and significantly increase the number of hydroxyl groups on the surface, providing reaction sites for the subsequent graft copolymerization reaction of acrylic acid.

[0036] By combining Preparation Examples 1-4 with Preparation Example 2 and referring to Table 1, it can be seen that the water absorption capacity of the modified plant fiber is greatly improved, indicating that the "cellulose-acrylate" network prepared by the present invention improves the water absorption and retention capacity as well as the absorption capacity of solutions with a certain ionic strength.

[0037] Taking Preparation Example 1 as an example, the following are embodiments of the present invention.

[0038] Example 1 This embodiment provides a plant fiber cement internal curing mortar, which is composed of the following raw materials by weight: This plant fiber cement internal curing mortar is prepared through the following steps: A1. Weigh the raw materials according to the mass fractions, pour the modified plant fiber into the water and stir for 5 minutes; mix the silicate cement and sand and stir for 10 minutes; A2. Pour the mixed water and modified plant fiber into the mixture of silicate cement and sand, stir for 10 minutes, then add silane coupling agent, stir again for 10 minutes, pour into the mold, and cure for 28 days after demolding.

[0039] Example 2 The difference from Example 1 is that the plant fiber cement internal curing mortar provided in this example is composed of the following raw materials by weight: This plant fiber cement internal curing mortar is prepared through the following steps: A1. Weigh the raw materials according to the mass fractions, pour the modified plant fiber into the water and stir for 10 minutes; mix the silicate cement and sand and stir for 20 minutes; A2. Pour the mixed water and modified plant fiber into the mixture of silicate cement and sand, stir for 10 minutes, then add silane coupling agent, stir again for 10 minutes, pour into the mold, and cure for 28 days after demolding.

[0040] Example 3 The difference from Example 1 is that the plant fiber cement internal curing mortar provided in this example is composed of the following raw materials by weight: The preparation steps are the same as in Example 1.

[0041] Example 4 The difference from Example 1 is that the plant fiber cement internal curing mortar provided in this example is composed of the following raw materials by weight: The preparation steps are the same as in Example 1.

[0042] Comparative Example 1 The difference from Example 1 is that corn stalks are used directly as plant fiber, the steps are adapted, and the rest remain unchanged.

[0043] Comparative Example 2 The difference from Example 1 is that the silane coupling agent KH550 was not used, the steps were adapted, and the rest remained unchanged.

[0044] Comparative Example 3 The difference from Example 1 is that the modified plant fiber used to prepare Comparative Example 1 was used, while the rest remained unchanged.

[0045] Comparative Example 4 The difference from Example 1 is that the modified plant fiber used to prepare Comparative Example 2 was used, while the rest remained unchanged.

[0046] Comparative Example 5 This comparative example provides a plant fiber alkali-activated geopolymer self-curing mortar, which is composed of the following raw materials by weight: The modified plant fiber was obtained from Preparation Example 1; The preparation method of the comparative plant fiber alkali-activated geopolymer involves the following steps: Weigh the raw materials according to the mass fractions, pour the modified plant fiber into water and stir for 5 minutes; add metakaolin, cement and water to the mixing pot and stir thoroughly until evenly mixed; add sodium hydroxide solution to the evenly mixed material in the mixing pot and stir thoroughly until evenly mixed; then add silane coupling agent KH550 and stir evenly; pour the evenly mixed material into a mold, cure and demold to produce plant fiber alkali-activated geopolymer.

[0047] Comparative Example 6 The difference from Comparative Example 5 is that corn stalks were used directly as plant fiber, the steps were adapted, and the rest remained unchanged.

[0048] Comparative Example 7 The difference from Comparative Example 5 is that the silane coupling agent KH550 was not used, the steps were adapted, and the rest remained the same.

[0049] Comparative Example 8 The difference from Comparative Example 5 is that the modified plant fiber used to prepare Comparative Example 1 was used, while the rest remained unchanged.

[0050] Comparative Example 9 The difference from Comparative Example 5 is that the modified plant fiber used to prepare Comparative Example 2 was used, while the rest remained unchanged.

[0051] Comparative Example 10 This comparative example provides a plant fiber acid-activated geopolymer self-curing mortar, which is composed of the following raw materials by weight: The modified plant fiber was obtained from Preparation Example 1; The preparation method of the comparative plant fiber alkali-activated geopolymer involves the following steps: Weigh the raw materials according to the mass fractions, pour the modified plant fiber into water and stir for 5 minutes; add metakaolin and phosphoric acid to the mixing pot and stir thoroughly until evenly mixed; add cement, water and modified plant fiber to the evenly mixed material in the mixing pot and stir thoroughly until evenly mixed; then add silane coupling agent KH550 and stir evenly; pour the evenly mixed material into a mold, cure and demold to produce plant fiber acid-activated geopolymer.

[0052] Comparative Example 11 The difference from Comparative Example 10 is that corn stalks were used directly as plant fiber, the steps were adapted, and the rest remained unchanged.

[0053] Comparative Example 12 The difference from Comparative Example 10 is that the silane coupling agent KH550 was not used, the steps were adapted, and the rest remained the same.

[0054] Comparative Example 13 The difference from Comparative Example 10 is that the modified plant fiber used to prepare Comparative Example 1 was used, while the rest remained unchanged.

[0055] Comparative Example 14 The difference from Comparative Example 10 is that the modified plant fiber used to prepare Comparative Example 2 was used, while the rest remained unchanged.

[0056] The properties of the 28-day curing mortars prepared in Examples 1-4 and Comparative Examples 1-14 were measured, and the results are shown in Table 2. The final setting time was based on GB / T 1346-2024; the flexural strength and compressive strength were tested according to GB / T17671-2021; the sulfate resistance test was conducted according to GB / T 50082-2009; and the freeze-thaw cycle test was conducted according to JGJ / T 70-2009.

[0057] Table 2 Performance Test Results As can be seen from Example 1, Comparative Example 1, and Table 2, the final setting time of the modified mortar is prolonged, but the strength of the cement is significantly improved. This is mainly attributed to the internal curing properties of the modified plant fibers, which regulate the hydration of the cement. After modification, the plant fibers have high water absorption and retention capacity, effectively maintaining the internal moisture of the mortar, mitigating spontaneous shrinkage, and improving the later degree of hydration and structural compactness. The denser cement matrix results in higher strength and significantly improved mortar durability.

[0058] As can be seen from Examples 1-4, Comparative Example 2, and Table 2, the addition of silane coupling agents KH550, KH560, and KH570 significantly improves the mechanical properties and durability of cement mortar. Appropriate incorporation of silane coupling agents slightly delays the early hydration of cement; however, this retarding effect is controllable and beneficial, allowing for more uniform and complete cement hydration. The resulting silicate hydrate structure is more tightly integrated with the modified plant fibers, contributing to improved later-stage strength and reduced harmful cracking.

[0059] As can be seen from Examples 1-4, Comparative Examples 3-10, and Table 2, the modified plant fiber self-curing additive proposed in this invention is not only applicable to cement mortar systems, but also has a significant reinforcing effect on acid-activated or alkali-activated geopolymer systems. This additive can effectively improve mechanical properties and durability, indicating that this invention has system versatility and wide applicability.

[0060] As can be seen from Comparative Examples 10 and 11 and Table 2, the modified plant fiber self-maintaining additive proposed in this invention temporarily stores water during mixing, continuously providing an aqueous phase for the polymerization reaction. This improves the interfacial compatibility between plant fibers and acid-activated geopolymer cementitious materials, increases the density of the system, reduces microcrack formation, and enhances durability.

[0061] As can be seen from Comparative Examples 10 and 12 and Table 2, the silane coupling agent in the modified plant fiber self-maintenance additive proposed in this invention can improve the strength and durability of the geopolymer. The silane coupling agent hydrolyzes in the mixing water to generate silanol, which associates with the geopolymer product to form a dense surface, thus enhancing the product's ability to inhibit the propagation of microcracks.

[0062] Combining Comparative Examples 10 and 13 and Table 2, it can be seen that hydrogen peroxide can remove some lignin and hemicellulose, increasing the grafting sites of acrylic acid. Without oxidation, the SAP network coefficient, water release capacity, and interfacial filling effect of the modified product are significantly weakened. Acid-activated geopolymer systems are more sensitive to the water-to-gel ratio and condensation hydrodynamics, thus reflecting a simultaneous decrease in strength and durability.

[0063] Combining Comparative Examples 10 and 14 and Table 2, it can be seen that traditional modification methods only remove surface impurities and improve wetting ability of plant fibers. However, plant fibers still only have the ability to passively absorb water and do not have the function of "water storage and release". Oxidized plant fibers may absorb some free water in the early stage of mixing, but it is difficult to release water in time, which amplifies the risk of voids and microcracks.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A modified plant fiber, characterized in that, By weight, it includes the following components: 5-10 parts plant straw, 50-100 parts hydrogen peroxide solution, 41.7-200 parts acrylic acid solution, 0.025-0.25 parts initiator, 0.2-0.64 parts crosslinking agent, and 50-70 parts deionized water.

2. The modified plant fiber as described in claim 1, characterized in that, The plant straw includes, but is not limited to, one or more of the following: corn stalks, sugarcane bagasse, rice straw, and rice husks.

3. The modified plant fiber as described in claim 2, characterized in that, The hydrogen peroxide solution has a mass concentration of 10-15 wt%, and the acrylic acid solution has a neutralization degree of 0.5-0.7 and a mass concentration of 40-60 wt%.

4. The modified plant fiber as described in claim 3, characterized in that, The acrylic solution is composed of 25-80 parts acrylic acid, 6.9-31.08 parts sodium hydroxide and 7-97.8 parts deionized water.

5. A method for preparing modified plant fiber as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. The pretreated plant straw is crushed and sieved to obtain plant fiber raw material; S2. After oxidizing the plant fiber raw material with hydrogen peroxide solution, acrylic acid solution, initiator, crosslinking agent and deionized water are added, and the mixture is heated and kept warm in a water bath under nitrogen protection to obtain pretreated fiber. S3. Clean and dry the pretreated fibers to obtain modified plant fibers.

6. The use of the modified plant fiber as described in any one of claims 1-4 in the preparation of plant fiber cement products.

7. A plant fiber cement product, characterized in that, The product comprises, by weight, 5-10 parts of the modified plant fiber as described in any one of claims 1-5; and also includes: 30 parts of silicate cement, 60-70 parts of sand, 0.5-2 parts of silane coupling agent, and 20-25 parts of water.

8. The plant fiber cement product as described in claim 7, characterized in that, The silicate cement is selected from one of P·O42.5, P·O 52.5, and P·C 42.5, and the sand has a particle size of 0.3-0.5 mm.

9. The cement internal curing additive as described in claim 7, characterized in that, The silane coupling agent includes, but is not limited to, one or more of aminosilane KH-550, epoxysilane KH-560, and acrylate silane KH570.

10. A method for preparing a plant fiber cement product as described in any one of claims 7-9, characterized in that, Includes the following steps: A1. Prepare raw materials according to the stated mass proportions, and mix the modified plant fiber with water and the silicate cement with sand respectively. A2. Add the modified plant fiber and water mixture to the mixture of silicate cement and sand, stir, then add the silane coupling agent and continue stirring; A3. Curing the mixture yields plant fiber cement products.

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