A composite material for cavity repair based on forestry waste and a method for preparing the same
Patent Information
- Application Number
- CN202611065069.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-17
- Publication Date
- 2026-10-20
AI Technical Summary
[0005]鉴于此，本发明的目的是提供一种基于林业废弃物的树洞修复用复合材料及其制备方法，解决木材由于天然多孔、吸湿性强，导致制备得到树洞修复材料的力学性能和长期稳定性降低的问题
[0028]1.本发明以木屑为主要原料，进行特定预处理后与氧化镁、氯化镁等混合制备复合材料，用于树洞的填充修复。本发明以木屑为主要成分制备修复材料，将林业废弃物转化为高附加值的生态修复材料，能够实现废弃物的资源化利用，减少木材燃烧过程中的碳排放，响应了国家绿色低碳的号召，还能对大气中二氧化碳进行捕获与封存，具有重要的生态和环保意义。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of tree cavity repair technology, and in particular to a composite material for tree cavity repair based on forestry waste and its preparation method. Background Technology
[0002] Ancient and famous trees refer to trees over a century old or those with rarity and historical value, possessing functions of ecological regulation, biological gene continuation, and cultural heritage. Due to factors such as pests and diseases, human damage, and natural disasters, the phloem of these trees may dry out and crack, while the xylem may be damaged and rotten. Under the combined action of rainwater and microorganisms, these wounds continue to deepen, gradually forming tree cavities of varying sizes, and in severe cases, even causing the tree to break or crack. Strengthening the protection of ancient and famous trees is of great significance for enhancing the ability to inherit historical and cultural heritage and promoting ecological civilization.
[0003] Traditional tree cavity restoration methods often employ fillings with materials such as soil, gravel, bricks, cement mortar, or concrete. These materials have poor physical and chemical compatibility with the tree, resulting in high shrinkage rates and elastic moduli after curing. They struggle to deform in sync with living trees, easily leading to cracks at the interface and even secondary physical damage due to expansion or contraction. Furthermore, these traditional materials lack biocompatibility, failing to integrate well with tree tissue and prone to detachment or exacerbating tree decay with prolonged use. In recent years, ecological restoration materials prepared from wood (such as infected wood and forest management waste) and bamboo, mixed with inorganic cementitious materials, have received widespread attention. Pine wilt disease is a major forest pest in my country, generating large quantities of pine wilt-infected wood in forest areas. Traditionally, this is primarily disposed of by incineration, resulting in significant resource waste. Utilizing forestry waste such as pine wilt-infected wood to prepare materials for tree cavity restoration of ancient and famous trees not only enables the reuse of forest waste resources but also avoids carbon emissions from incineration, responding to the national "carbon neutrality" strategy. Furthermore, the prepared repair material combines the flexibility of wood fibers with the strength of inorganic cementitious materials, exhibiting excellent mechanical properties, durability, and biocompatibility. It can integrate well with tree tissue, promoting healthy tree growth and showing promising application prospects in tree cavity filling and repair. However, due to its natural porosity and high hygroscopicity, wood expands after absorbing water and shrinks after drying. This volume change can cause cracking in the repair material matrix and reduce the bond strength between the wood and the cementitious material, thereby decreasing the mechanical properties and long-term stability of the composite material, limiting its practical application.
[0004] Therefore, there is an urgent need to find a method to prepare tree cavity repair materials using wood as the main raw material, in order to solve the problem that the mechanical properties and long-term stability of the prepared tree cavity repair materials are reduced due to the natural porosity and strong hygroscopicity of wood. Summary of the Invention
[0005] Therefore, the purpose of this invention is to provide a composite material for tree cavity repair based on forestry waste and its preparation method, which solves the problem that the mechanical properties and long-term stability of the prepared tree cavity repair material are reduced due to the natural porosity and strong hygroscopicity of wood.
[0006] The present invention solves the above-mentioned technical problems through the following technical means:
[0007] A composite material for repairing tree cavities based on forestry waste, the composite material comprising the following parts by weight of raw materials:
[0008] The pretreated wood chips consist of 25-50 parts, sodium lauroyl hydroxyethyl sulfonate 0.1-0.4 parts, disodium hydrogen phosphate 1.5-3.0 parts, fly ash 8-20 parts, magnesium oxide 18-32 parts, magnesium chloride 6-15 parts, and water 25-45 parts.
[0009] The present invention also discloses a method for preparing the composite material, the specific method of which is as follows:
[0010] After mixing pretreated sawdust, fly ash, and magnesium oxide evenly, add disodium hydrogen phosphate and sodium lauroyl hydroxyethyl sulfonate and mix evenly to obtain a mixture. Add magnesium chloride to water and stir to dissolve, then add it to the mixture. Continue stirring and mixing for 8-10 minutes to obtain a composite material, which can then be used to fill and repair the tree cavity.
[0011] Furthermore, the composite material is prepared at room temperature.
[0012] Preferably, the composite material is prepared at 15–25°C.
[0013] This invention uses sawdust as the main raw material, combined with inorganic cementing materials such as magnesium oxide and magnesium chloride, to prepare a remediation material. This material can transform forestry waste into a high-value-added ecological restoration material, repairing hollow or decayed tree cavities to enhance tree structural stability and promote healthy tree growth. Wood-based materials have good affinity with trees, effectively avoiding the mechanical damage problems associated with traditional rigid materials. Furthermore, the prepared composite material can capture and store carbon dioxide from the atmosphere, possessing significant ecological and environmental benefits.
[0014] Furthermore, the method for preparing the pretreated wood chips is as follows:
[0015] (1) After the sawdust is crushed and dried, it is soaked in lime water at room temperature for 12-24 hours, then taken out and washed with water until the pH is 7-8 to obtain primary treated sawdust;
[0016] (2) Add the primary treated wood chips to 5 times the mass of water and stir to disperse. Then add phytic acid, urea and dicyandiamide. Stir and react at room temperature for 30-60 min. Then raise the temperature to 100-120℃ and stir to react for 2-4 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry to obtain phytic acid modified wood chips.
[0017] (3) Place the phytic acid modified wood chips in a sealed container, vacuum it to -0.06MPa to -0.09MPa for 10 to 20 minutes, then add sodium silicate solution with a mass of 3 times that of the phytic acid modified wood chips, pressurize it to 0.3MPa to 1.0MPa and treat it for 0.5 to 1 hour. After treatment, take out the wood chips and dry them to obtain sodium silicate treated wood chips.
[0018] (4) Add sodium silicate treated wood chips to water and stir to disperse them. Then add zinc sulfate heptahydrate and stir continuously at 100-200 r / min for 30-60 min. Then add 2-methylimidazole, heat to 40-50℃ and stir to react for 3-6 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry to obtain pretreated wood chips.
[0019] Furthermore, in step (1), the wood chips are crushed to a particle size of 1-5 mm and dried to a moisture content of ≤12%.
[0020] Furthermore, the lime water concentration in step (1) is 5 wt%.
[0021] Furthermore, in step (2), the mass ratio of primary treated wood chips, phytic acid, urea, and dicyandiamide is 50:(2.5-5):(0.15-0.25):(0.36-0.6).
[0022] Furthermore, in step (3), the concentration of the sodium silicate solution is 20-30 wt%, and the modulus is 3.2.
[0023] Furthermore, in step (4), the mass ratio of sodium silicate-treated wood chips, zinc sulfate heptahydrate, and 2-methylimidazole is 50:(2.5-5):(2-4).
[0024] Furthermore, in step (4), the drying temperature is 60-80°C, and the product is dried until the moisture content is ≤10%.
[0025] This invention prepares a composite material for tree cavity repair using wood chips as the main component. However, due to the natural porosity and strong hygroscopicity of wood, it is easy to absorb water and expand after filling and repairing tree cavities, and shrink when drying, which leads to volume changes, causing cracks in the composite matrix, reducing the bonding strength between the wood and the gel material, and reducing its long-term stability. Therefore, this invention pre-treats the wood chips to reduce their porosity and hygroscopicity, so as to ensure the mechanical properties and long-term stability of the prepared composite material.
[0026] Specifically, this invention first treats sawdust with lime water to obtain primary treated sawdust, removing sugars and phenols to prevent them from combining with calcium and magnesium ions in the material to form insoluble substances that coat the material surface and hinder the normal hydration reaction. Then, phytic acid is added to produce phytic acid-modified sawdust. Phytic acid esterifies with groups in the sawdust, shielding hydrophilic groups and reducing hygroscopicity. Simultaneously, phosphate groups form stable coordination structures with magnesium ions in the subsequent material, enhancing the interfacial bonding between the sawdust and the material and improving the mechanical properties of the composite material. Further, sodium silicate solution is added for impregnation. Sodium silicate seals the pore structure of the sawdust, preventing residual sugars and phenols from dissolving during composite material preparation and affecting the hydration reaction. Simultaneously, a film layer forms on the sawdust surface to further reduce its hygroscopic swelling. Finally, the sawdust is pretreated by sequentially treating it with zinc sulfate heptahydrate and 2-methylimidazole. The coordination reaction between zinc sulfate heptahydrate and 2-methylimidazole allows for the formation of a highly crystalline and hydrophobic stable framework material within the sawdust, reducing its porosity and water retention, thus improving the mechanical properties of the composite material. Simultaneously, zinc ions exhibit excellent bactericidal and bacteriostatic effects, effectively inhibiting sawdust decay. Pretreatment of sawdust using the method of this invention effectively reduces its hygroscopicity and enhances its stability, thereby endowing the composite material with excellent mechanical properties and water resistance, and improving its long-term stability in tree cavity repair.
[0027] Beneficial effects:
[0028] 1. This invention uses sawdust as the main raw material, which, after specific pretreatment, is mixed with magnesium oxide, magnesium chloride, etc., to prepare a composite material for filling and repairing tree cavities. This invention uses sawdust as the main component to prepare a restoration material, transforming forestry waste into a high-value-added ecological restoration material. It enables the resource utilization of waste, reduces carbon emissions during wood combustion, responds to the national call for green and low-carbon development, and can also capture and store carbon dioxide in the atmosphere, thus having significant ecological and environmental protection implications.
[0029] 2. This invention uses phytic acid, sodium silicate, zinc sulfate heptahydrate, and 2-methylimidazole to pretreat wood chips, which can effectively reduce the porosity and hygroscopicity of the wood chips, ensuring the good mechanical properties, water resistance, and long-term stability of the composite material. It is suitable for tree cavity repair in different environments and has good application prospects. Attached Figure Description
[0030] Figure 1 : Images showing the crushing process of Masson pine wood, the raw material used in the composite material of this invention;
[0031] Figure 2 Images showing the preparation process of the composite material of this invention;
[0032] Figure 3 Image: A picture of the composite material prepared in this invention being pressed and molded. Detailed Implementation
[0033] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings:
[0034] This invention discloses a composite material for tree cavity repair based on forestry waste and its preparation method. Specifically, it uses wood chips obtained after harmless treatment of infected Masson pine as raw material to further prepare the composite material for tree cavity repair, as shown below.
[0035] Example 1: Preparation of composite materials
[0036] Pre-treatment of wood chips:
[0037] (1) The sawdust was crushed to a particle size of about 4 mm, then dried to a moisture content of 10%, soaked in 5 wt% lime water at room temperature for 18 h, then taken out and washed with water until the pH was 7.5 to obtain primary treated sawdust.
[0038] (2) Add 50 kg of primary treated wood chips to 5 times the mass of water and stir to disperse. Then add 4 kg of phytic acid, 0.2 kg of urea and 0.45 kg of dicyandiamide. Stir and react at room temperature for 45 min, then heat to 1110℃ and stir and react for 3 h. After the reaction is complete, filter to remove the filtrate, wash with water and dry at 60℃ to constant weight to obtain phytic acid modified wood chips.
[0039] (3) Place the phytic acid modified wood chips in a sealed container, vacuum to -0.08MPa for 15 min, then add 3 times the mass of the phytic acid modified wood chips and 25wt% sodium silicate solution with a modulus of 3.2, pressurize to 0.6MPa and treat for 0.6 h. After treatment, take out the wood chips and dry them at 60℃ to constant weight to obtain sodium silicate treated wood chips.
[0040] (4) Add 50 kg of sodium silicate treated wood chips to 5 times the mass of water and stir to disperse. Then add 4 kg of zinc sulfate heptahydrate and stir continuously at 150 r / min for 45 min. Then add 3 kg of 2-methylimidazole, heat to 45℃ and stir to react for 4 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry at 70℃ until the moisture content is 8% to obtain pretreated wood chips.
[0041] Composite material preparation:
[0042] 37 kg of pretreated wood chips, 16 kg of fly ash and 26 kg of magnesium oxide were mixed evenly, and then 2.6 kg of disodium hydrogen phosphate and 0.32 kg of sodium lauroyl hydroxyethyl sulfonate were added and mixed evenly to obtain a mixture. 12 kg of magnesium chloride was added to 40 kg of water and stirred to dissolve, and then added to the mixture. The mixture was stirred and mixed for 9 minutes to obtain a composite material.
[0043] Example 2: Preparation of Composite Materials
[0044] Pre-treatment of wood chips:
[0045] (1) The sawdust was crushed to a particle size of about 4 mm, then dried to a moisture content of 10%, soaked in 5 wt% lime water at room temperature for 12 h, then taken out and washed with water until the pH was 7 to obtain primary treated sawdust.
[0046] (2) Add 50 kg of primary treated wood chips to 5 times the mass of water and stir to disperse. Then add 2.5 kg of phytic acid, 0.15 kg of urea and 0.36 kg of dicyandiamide. Stir at room temperature for 30 min and then heat to 100 °C and stir for 4 h. After the reaction is complete, filter to remove the filtrate, wash with water and dry at 60 °C to constant weight to obtain phytic acid modified wood chips.
[0047] (3) Place the phytic acid modified wood chips in a sealed container, vacuum to -0.06MPa for 20min, then add 3 times the mass of the phytic acid modified wood chips and 20wt% sodium silicate solution with a modulus of 3.2, pressurize to 0.3MPa for 1h, remove the wood chips and dry them at 60℃ to constant weight to obtain sodium silicate treated wood chips.
[0048] (4) Add 50 kg of sodium silicate treated wood chips to 5 times the mass of water and stir to disperse. Then add 2.5 kg of zinc sulfate heptahydrate and stir continuously at 100 r / min for 60 min. Then add 2 kg of 2-methylimidazole, heat to 40℃ and stir to react for 6 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry at 60℃ until the moisture content is 10% to obtain pretreated wood chips.
[0049] Composite material preparation:
[0050] 25 kg of pretreated wood chips, 8 kg of fly ash and 18 kg of magnesium oxide were mixed evenly, and then 1.5 kg of disodium hydrogen phosphate and 0.1 kg of sodium lauroyl hydroxyethyl sulfonate were added and mixed evenly to obtain a mixture. 6 kg of magnesium chloride was added to 25 kg of water and stirred to dissolve, and then added to the mixture. The mixture was stirred and mixed for 8 minutes to obtain a composite material.
[0051] Example 3: Preparation of Composite Materials
[0052] Pre-treatment of wood chips:
[0053] (1) The sawdust was crushed to a particle size of about 4 mm, then dried to a moisture content of 12%, soaked in 5 wt% lime water at room temperature for 24 h, then taken out and washed with water until the pH was 8 to obtain primary treated sawdust.
[0054] (2) Add 50 kg of primary treated wood chips to 5 times the mass of water and stir to disperse. Then add 5 kg of phytic acid, 0.25 kg of urea and 0.6 kg of dicyandiamide. Stir at room temperature for 60 min and then heat to 120 °C and stir for 2 h. After the reaction is complete, filter to remove the filtrate, wash with water and dry at 60 °C to constant weight to obtain phytic acid modified wood chips.
[0055] (3) Place the phytic acid modified wood chips in a sealed container, vacuum to -0.09MPa for 20min, then add 30wt% sodium silicate solution with a modulus of 3.2, 3 times the mass of the phytic acid modified wood chips, pressurize to 1.0MPa for 0.5h, remove the wood chips and dry them at 60℃ to constant weight to obtain sodium silicate treated wood chips;
[0056] (4) Add 50 kg of sodium silicate treated wood chips to 5 times the mass of water and stir to disperse. Then add 5 kg of zinc sulfate heptahydrate and stir continuously at 200 r / min for 60 min. Then add 4 kg of 2-methylimidazole, heat to 50℃ and stir to react for 3 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry at 80℃ until the moisture content is 10% to obtain pretreated wood chips.
[0057] Composite material preparation:
[0058] 48 kg of pretreated wood chips, 20 kg of fly ash and 32 kg of magnesium oxide were mixed evenly, and then 3.0 kg of disodium hydrogen phosphate and 0.4 kg of sodium lauroyl hydroxyethyl sulfonate were added and mixed evenly to obtain a mixture. 15 kg of magnesium chloride was added to 45 kg of water and stirred to dissolve, and then added to the mixture. The mixture was stirred and mixed for 10 minutes to obtain a composite material.
[0059] Comparative Example 1: Preparation of Composite Materials
[0060] Compared with Example 1, the only difference is that in the preparation of the pretreated wood chips in Comparative Example 1, the chips are not treated with lime water in step (1). All other steps are the same as in Example 1, as shown below:
[0061] Pre-treatment of wood chips:
[0062] (1) The sawdust is crushed to a particle size of about 4 mm and then dried to a moisture content of 10% to obtain primary treated sawdust;
[0063] (2) to (4) are the same as in Example 1;
[0064] Composite material preparation: Same as in Example 1.
[0065] Comparative Example 2: Preparation of Composite Materials
[0066] Compared with Example 1, the only difference is that the pre-treated wood chips in Comparative Example 2 are prepared without the original step (2), i.e., phytic acid is not used for treatment. All other steps are the same as in Example 1, as shown below:
[0067] Pre-treatment of wood chips:
[0068] (1) Same as Example 1;
[0069] (2) Place the primary treated wood chips in a sealed container, vacuum to -0.08MPa for 15 min, then add 25wt% sodium silicate solution with a modulus of 3.2, 3 times the mass of the primary treated wood chips, pressurize to 0.6MPa for 0.6 h, remove the wood chips and dry them at 60℃ to constant weight to obtain sodium silicate treated wood chips.
[0070] (3) Same as step (4) in Example 1;
[0071] Composite material preparation: Same as in Example 1.
[0072] Comparative Example 3: Preparation of Composite Materials
[0073] Compared with Example 1, the only difference is that the pre-treated wood chips in Comparative Example 3 are prepared without the original step (3), i.e., sodium silicate is not used for treatment. All other steps are the same as in Example 1, as shown below:
[0074] Pre-treatment of wood chips:
[0075] (1) to (2) are the same as in Example 1;
[0076] (3) Add 50 kg of phytic acid modified wood chips to 5 times the mass of water and stir to disperse. Then add 4 kg of zinc sulfate heptahydrate and stir continuously at 150 r / min for 45 min. Then add 3 kg of 2-methylimidazole, heat to 45℃ and stir to react for 4 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry at 70℃ until the moisture content is 8% to obtain pretreated wood chips.
[0077] Composite material preparation: Same as in Example 1.
[0078] Comparative Example 4: Preparation of Composite Materials
[0079] Compared with Example 1, the only difference is that the pre-treated wood chips in Comparative Example 4 were prepared without the original step (4), i.e., zinc sulfate heptahydrate and 2-methylimidazole were not used for treatment. All other steps were the same as in Example 1, as shown below:
[0080] Pre-treatment of wood chips:
[0081] (1)~(2): Same as in Example 1;
[0082] (3) Place the phytic acid modified wood chips in a sealed container, vacuum to -0.08MPa for 15 min, then add 3 times the mass of the phytic acid modified wood chips and 25wt% sodium silicate solution with a modulus of 3.2, pressurize to 0.6MPa and treat for 0.6 h. After treatment, take out the wood chips and dry them at 60℃ to constant weight to obtain pretreated wood chips.
[0083] Composite material preparation: Same as in Example 1.
[0084] Comparative Example 5: Preparation of Composite Materials
[0085] Compared with Example 1, the only difference is that steps (2), (3), and (4) were omitted in the preparation of pretreated wood chips in the composite material of Comparative Example 5. That is, the pretreated wood chips were obtained directly by conventional alkali treatment, as shown below:
[0086] Pre-treatment of wood chips:
[0087] The sawdust was crushed to a particle size of about 4 mm, then dried to a moisture content of 10%, soaked in 5 wt% lime water at room temperature for 18 hours, then removed and washed with water until the pH reached 7.5 to obtain primary treated sawdust.
[0088] Composite material preparation: Same as in Example 1.
[0089] Comparative Example 6: Preparation of Composite Materials
[0090] In contrast to Example 1, the only difference is that in Comparative Example 6, the wood chips were not processed during the preparation of the composite material; the composite material was prepared directly, as shown below:
[0091] 37 kg of sawdust with a particle size of about 4 mm, 16 kg of fly ash and 26 kg of magnesium oxide were mixed evenly, and then 2.6 kg of disodium hydrogen phosphate and 0.32 kg of sodium lauroyl hydroxyethyl sulfonate were added and mixed evenly to obtain a mixture. 12 kg of magnesium chloride was added to 40 kg of water and stirred to dissolve, and then added to the mixture. The mixture was stirred and mixed for 9 minutes to obtain a composite material.
[0092] Experiment: Composite Material Performance Testing Experiment
[0093] The composite materials for tree cavity repair prepared in Example 1 and Comparative Examples 1-6 were pressed into molds and placed in a constant temperature and humidity chamber for standard curing (temperature 22℃, humidity 95%). After curing for 28 days, the samples were dried to constant weight. The compressive strength and flexural strength of each group of composite material samples were tested. The water absorption rate of each group of samples was tested by immersing them in water for 24 hours. The softening coefficient of each group of samples was tested by immersing them in water for 28 days. Three repeated experiments were conducted, and the average data are shown in Table 1.
[0094] Table 1
[0095]
[0096] Based on the data analysis in Table 1, we can conclude that:
[0097] (1) The compressive strength and flexural strength of the composite material sample in Example 1 reached 20.7 MPa and 6.6 MPa, respectively. The water absorption rate was 6.2% and the softening coefficient was 0.99. However, in Comparative Example 6, without any treatment of the wood chips, the compressive strength and flexural strength decreased to 13.8 MPa and 4.2 MPa, respectively. The water absorption rate increased to 19.8% and the softening coefficient decreased to 0.79. This indicates that the composite material prepared according to the method of the present invention has excellent mechanical properties and good water resistance. Furthermore, with wood chips as the main component, it has good affinity with trees and has good applicability in tree cavity filling and repair.
[0098] (2) In Comparative Example 1, lime water was not used for the preparation of the composite material, and the phenols and sugars in the wood chips interfered with the hydration reaction, resulting in a significant decrease in the mechanical properties of the material. In Comparative Example 2, phytic acid was not used for the preparation of the composite material, resulting in a significant increase in the water absorption rate of the composite material. In Comparative Example 3, sodium silicate was not used for modification during the preparation of the composite material, and zinc sulfate heptahydrate and 2-methylimidazole were not used for the preparation of the composite material in Comparative Example 4. The mechanical properties and water resistance of the composite materials in Comparative Example 3 and Comparative Example 4 were significantly reduced.
[0099] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.
Claims
1. A composite material for repairing tree cavities based on forestry waste, characterized in that, The composite material comprises the following raw materials in parts by weight: The pretreated wood chips consist of 25-50 parts, sodium lauroyl hydroxyethyl sulfonate 0.1-0.4 parts, disodium hydrogen phosphate 1.5-3.0 parts, fly ash 8-20 parts, magnesium oxide 18-32 parts, magnesium chloride 6-15 parts, and water 25-45 parts.
2. A method for preparing a composite material for tree cavity repair based on forestry waste, characterized in that, The specific method for preparing the composite material is as follows: After mixing pretreated sawdust, fly ash, and magnesium oxide evenly, add disodium hydrogen phosphate and sodium lauroyl hydroxyethyl sulfonate and mix evenly to obtain a mixture. Add magnesium chloride to water and stir to dissolve, then add it to the mixture. Continue stirring and mixing for 8-10 minutes to obtain a composite material, which can then be used to fill and repair the tree cavity.
3. The method for preparing a composite material for tree cavity repair based on forestry waste according to claim 2, characterized in that, The method for preparing the pretreated wood chips is as follows: (1) After the sawdust is crushed and dried, it is soaked in lime water at room temperature for 12-24 hours, then taken out and washed with water until the pH is 7-8 to obtain primary treated sawdust; (2) Add the primary treated wood chips to 5 times the mass of water and stir to disperse. Then add phytic acid, urea and dicyandiamide. Stir and react at room temperature for 30-60 min. Then raise the temperature to 100-120℃ and stir to react for 2-4 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry to obtain phytic acid modified wood chips. (3) Place the phytic acid modified wood chips in a sealed container, vacuum it to -0.06MPa to -0.09MPa for 10 to 20 minutes, then add sodium silicate solution with a mass of 3 times that of the phytic acid modified wood chips, pressurize it to 0.3MPa to 1.0MPa and treat it for 0.5 to 1 hour. After treatment, take out the wood chips and dry them to obtain sodium silicate treated wood chips. (4) Add sodium silicate treated wood chips to water and stir to disperse them. Then add zinc sulfate heptahydrate and stir continuously at 100-200 r / min for 30-60 min. Then add 2-methylimidazole, heat to 40-50℃ and stir to react for 3-6 h. After the reaction is completed, filter to remove the filtrate, wash with water and dry to obtain pretreated wood chips.
4. The method for preparing a composite material for tree cavity repair based on forestry waste according to claim 3, characterized in that, In step (1), the wood chips are crushed to a particle size of 1-5 mm and dried to a moisture content of ≤12%.
5. The method for preparing a composite material for tree cavity repair based on forestry waste according to claim 4, characterized in that, The concentration of lime water in step (1) is 5 wt%.
6. The method for preparing a composite material for tree cavity repair based on forestry waste according to claim 5, characterized in that, In step (2), the mass ratio of primary treated sawdust, phytic acid, urea, and dicyandiamide is 50:(2.5-5):(0.15-0.25):(0.36-0.6).
7. The method for preparing a composite material for tree cavity repair based on forestry waste according to claim 6, characterized in that, In step (3), the sodium silicate solution has a concentration of 20-30 wt% and a modulus of 3.
2.
8. The method for preparing a composite material for tree cavity repair based on forestry waste according to claim 7, characterized in that, In step (4), the mass ratio of sodium silicate-treated wood chips, zinc sulfate heptahydrate, and 2-methylimidazole is 50:(2.5-5):(2-4).
9. A method for preparing a composite material for tree cavity repair based on forestry waste according to claim 8, characterized in that, In step (4), the drying temperature is 60-80℃, and the product is dried until the moisture content is ≤10%.