Preparation method of modified fiber and application of modified fiber in concrete product

Abstract

The invention discloses a preparation method of a modified fiber and application of the modified fiber in a concrete product. The preparation method comprises the following steps: soaking the fiber in a sodium hydroxide solution; then washing with deionized water and ethanol for multiple times; adding the washed solid and gamma-aminopropyltriethoxysilane into a mixed solution of ethanol and deionized water to obtain a mixed solution, and stirring, standing, filtering and separating the solution to obtain a solid; and adding the solid into water-borne epoxy resin, uniformly stirring, airing, shaping, and cutting into short fibers to finally obtain the modified fibers. Surface treatment including alkali soaking, washing and coupling is carried out on fibers, so that the surface roughness of the fibers is remarkably improved, and impurities and charges on the surfaces of the fibers are removed; the surface-treated fibers are coated with the waterborne epoxy resin, the dispersity of the modified fibers in the green body is effectively improved, meanwhile, the waterborne epoxy resin can react with concrete particles, the performance of the concrete plate is further enhanced, and the size of the finished concrete plate is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of fiber modification, and more specifically, relates to a method for preparing modified fiber and application of the modified fiber in concrete products. Background Art

[0002] Autoclaved aerated concrete board is a porous board made of siliceous and calcareous materials as the main raw materials, mixed with gas-generating agents, and made through processes such as casting, pre-curing, cutting, and steam curing, and the pores are formed by chemical reactions. The internal porosity of the board can be as high as 70% to 80%. This high porosity greatly reduces the unit bulk density of the material, and its bulk density is generally 300 to 800 kg / m 3 . Due to its outstanding light weight, high strength, thermal insulation, fire resistance, sound insulation, and green environmental protection performance, it has been more and more widely used in buildings, and has made outstanding contributions to energy conservation and consumption reduction in buildings. In general, due to the large porosity and small effective bearing area of ​​autoclaved aerated concrete boards, the strength of the boards is generally low. In addition, there is no coarse aggregate in the autoclaved aerated concrete board, the degree of crystallization of the hydration product is very high, and the resistance to plastic deformation is poor.

[0003] In order to enhance the ability of autoclaved aerated concrete panels to resist deformation and damage and improve the mechanical properties of the panels, autoclaved aerated concrete panel production factories at home and abroad will add steel bars inside the panels. These steel bars form steel mesh and play a role in skeleton support to maintain the integrity of the panels. This can not only combine with concrete particles to bear external forces and improve the anti-bending and anti-deformation capabilities of the panels, but also transfer the load on the panels to the entire panels to disperse the load. However, the setting of plate steel bars in autoclaved aerated concrete panels also leads to increased material costs; secondly, the expansion coefficients of steel bars and slurry are different, and large bubbles are easily formed during the steaming process, and then together with the formation of gas layers, the green body is unevenly gasified and the panels are easily damaged; in addition, due to the porous structure of autoclaved aerated concrete, although the crystals provide strength, the crack resistance and nail holding force are insufficient. The panels with added steel bars are not easy to groove, and the steel bars are prone to rust after cutting. The unqualified anti-rust layer and the internal stress of long-term oxidation and rust are also prone to cracking.

[0004] In order to solve the above problems, the prior art adds fiber-reinforced materials to traditional autoclaved aerated concrete panels to replace traditional steel reinforcement technology, which can effectively improve the generation and development of microcracks inside the panels and reduce shrinkage cracks, temperature cracks, etc. in the panels. Although the existing fiber-reinforced autoclaved aerated concrete panels have been significantly improved in terms of material performance and cost compared to traditional reinforced autoclaved aerated concrete panels, the strength of the chopped fibers is lower than that of steel bars and they are easy to agglomerate into flocculation, resulting in the finished size of the concrete panels using fibers instead of steel bars not being comparable to that of traditional reinforced autoclaved aerated concrete panels. This limitation not only affects its application in engineering, but also reduces construction efficiency. Therefore, there is an urgent need for a new material or technology that can solve these problems. Summary of the invention

[0005] In view of the above defects or improvement needs of the prior art, the present invention provides a method for preparing modified fibers and the application of the modified fibers in concrete products. The fibers are subjected to surface treatments including alkali soaking, washing, and coupling to significantly improve the surface roughness of the fibers and remove surface impurities and charges, thereby facilitating their contact with concrete particles. Secondly, the surface-treated fibers are coated with a water-based epoxy resin to effectively improve the dispersibility of the modified fibers in the green body and avoid agglomeration into flocs. At the same time, the water-based epoxy resin can react with concrete particles to further enhance the performance of the concrete slab and improve the size of the finished concrete slab.

[0006] In order to achieve the above object, the present invention provides a method for preparing a modified fiber, comprising the following steps:

[0007] S1: soaking the fiber in a 5-15% sodium hydroxide solution for 0.5-2h to obtain solution a;

[0008] S2: Filter the solution a to separate the solid a, and wash the solid a multiple times with deionized water and ethanol;

[0009] S3: preparing a mixed solution b of ethanol and deionized water, wherein the volume ratio of the two is between 7.5:2.5 and 8.5:1.5; adding a and γ-aminopropyltriethoxysilane to the solution b, wherein the mass ratio of the two is maintained in the range of 1.2:1.6 to 0.8:2.4, thereby obtaining a solution c, stirring the solution c, standing it for 1 hour, and then filtering and separating to obtain a solid b;

[0010] S4: adding solid b into waterborne epoxy resin and controlling the mass ratio of the two within the range of 1.2:1.6 to 0.8:2.4, stirring the mixture evenly and drying it to set it, and then cutting it into short fibers of uniform specifications to finally obtain modified fibers.

[0011] Further, in step S1, the temperature range of the sodium hydroxide solution is preferably 20°C-40°C;

[0012] The sodium hydroxide solution is prepared by preparing industrial sodium hydroxide solid, wherein the industrial sodium hydroxide comprises: NaOH≥90%, Na2CO3≤0.65, NaCl≤0.05, and Fe2O3≤0.008.

[0013] Furthermore, in step S2, the washing times are at least three times.

[0014] Furthermore, in step S3, solution c is treated by stirring for 15 minutes, standing for 15 minutes, and cycling twice.

[0015] Furthermore, in the γ-aminopropyltriethoxysilane, the γ-aminopropyltriethoxysilane content is ≥96%, the water content is ≤0.5%, and the specific gravity at 25°C is 0.9390-0.9430 g / ml.

[0016] Furthermore, the drying method includes air drying at room temperature, forced ventilation drying or heating drying.

[0017] Furthermore, in the waterborne epoxy resin: solid content ≥50%, water content ≤30%, epoxy value is 0.3-0.5meq / 100g.

[0018] Furthermore, the ethanol used for washing in step S2 and the ethanol used for preparing the solution in steps S3 and S4 are all anhydrous ethanol, and wherein: the mass fraction of ethanol is ≥99.5%, the mass fraction of water is ≤0.5%, and the density at 20°C is 0.789-0.791%.

[0019] Further, the fiber in the preparation method includes at least one of basalt fiber and PTFE fiber;

[0020] The length of the modified fiber is 0.1-20 mm.

[0021] Another aspect of the present invention provides an application of modified fibers in concrete products, wherein the modified fibers are prepared according to the preparation method described above, and the modified fibers are used to completely replace steel bars and unmodified fibers to prepare autoclaved aerated concrete panels;

[0022] The autoclaved aerated concrete slabs are mainly non-load-bearing walls of buildings, including interior walls and exterior walls.

[0023] Furthermore, the modified fiber is used as an anti-cracking treatment additive, and is suitable for but not limited to: building concrete, lightweight concrete, municipal asphalt concrete, and high-strength concrete for bridges.

[0024] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0025] 1. The preparation method of the present invention significantly improves the surface roughness of the fiber and removes its surface impurities and charges by subjecting the fiber to surface treatment including alkali soaking, washing and coupling, thereby facilitating its contact with concrete particles. Secondly, the surface-treated fiber is coated with a water-based epoxy resin, thereby effectively improving the dispersibility of the modified fiber in the green body and avoiding agglomeration into flocculation. At the same time, the water-based epoxy resin can react with concrete particles to further enhance the performance of the concrete board and improve the size of the finished concrete board.

[0026] 2. The preparation method of the present invention etches holes on the surface of the basalt fiber by alkali soaking, making the surface of the basalt fiber rough; at the same time, the silanol and aluminum hydroxyl functional groups inside the basalt fiber are exposed, which is beneficial to the close combination of cement and basalt fiber in the subsequent preparation process of autoclaved aerated concrete board.

[0027] 3. The preparation method of the present invention effectively removes impurities and ions on the fiber surface through multiple washings, thereby reducing the accumulation of static electricity caused by impurities and ions.

[0028] 4. The preparation method of the present invention shapes the modified fiber through the water-based epoxy resin, which facilitates the control of its length, thereby effectively improving its fluidity in the concrete slurry and making it evenly distributed in the plate; secondly, it avoids the phenomenon that longer fibers are pulled out or broken during the cutting process, resulting in uneven incisions, increased burrs, and other factors that affect the quality of the cutting surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic flow chart of the steps of the method for preparing modified fibers according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of a method for preparing modified fibers according to an embodiment of the present invention;

[0031] Figure 3 This is a microstructure diagram of the fiber of the embodiment of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] like Figure 1 As shown, the present invention provides a method for preparing a modified fiber, comprising the following steps:

[0034] S1: soaking the fiber in a 5-15% sodium hydroxide solution for 0.5-2h to obtain solution a;

[0035] S2: Filter the solution a to separate the solid a, and wash the solid a multiple times with deionized water and ethanol;

[0036] S3: preparing a mixed solution b of ethanol and deionized water, wherein the volume ratio of the two is between 7.5:2.5 and 8.5:1.5; adding a and γ-aminopropyltriethoxysilane to the solution b, wherein the mass ratio of the two is maintained in the range of 1.2:1.6 to 0.8:2.4, thereby obtaining a solution c, stirring the solution c, standing it for 1 hour, and then filtering and separating to obtain a solid b;

[0037] S4: adding solid b into waterborne epoxy resin and controlling the mass ratio of the two within the range of 1.2:1.6 to 0.8:2.4, stirring the mixture evenly and drying it to set it, and then cutting it into short fibers of uniform specifications to finally obtain modified fibers.

[0038] Specifically, in step S1, the hydroxide ions in the sodium hydroxide solution will corrode the -Si-O-Si- and -Al-O-Si- skeletons of the basalt fiber, etch holes on the surface of the basalt fiber, and make the surface of the basalt fiber rough; at the same time, the silicon hydroxyl and aluminum hydroxyl functional groups inside the basalt fiber are exposed, which is beneficial to the close combination of cement and basalt fiber in the subsequent preparation process of autoclaved aerated concrete board.

[0039] It can be understood that the fiber immersion time in the sodium hydroxide solution decreases as the temperature of the sodium hydroxide solution increases, but in order to avoid excessive damage to the fiber structure by the sodium hydroxide solution, the reaction time can be appropriately shortened; wherein the temperature range of the sodium hydroxide solution is preferably 20C°-40C°; more preferably 20C°-30C°, so as to increase the flexibility of controlling the degree of reaction of the two.

[0040] Preferably, the sodium hydroxide solution is prepared by industrial sodium hydroxide solid, wherein: NaOH ≥ 90%, Na2CO3 ≤ 0.65, NaCl ≤ 0.05, Fe2O3 ≤ 0.008.

[0041] Specifically, in step S2, solid a is fully washed multiple times by circulating deionized water and ethanol in sequence, and the washing times are at least three times, so as to completely remove the sodium hydroxide solution on the surface of solid a until it is neutral, effectively avoiding the subsequent impact on the chemical properties of the water-based epoxy resin. At the same time, by washing the fiber surface with deionized water, impurities and ions on the fiber surface can be effectively removed, reducing the static electricity accumulation caused by impurities and ions; by washing the fiber surface with ethanol, non-polar and weakly polar pollutants that may exist on the dissolved fiber surface, such as grease, wax, etc., can be effectively removed, thereby further reducing the static electricity accumulation caused by impurities.

[0042] Specifically, in step S3, by adding γ-aminopropyl triethoxysilane to the mixed solution b of ethanol and deionized water, the hydrolysis of the alkoxy silicon functional group of γ-aminopropyl triethoxysilane can be promoted to generate silicon hydroxyl groups. At the same time, the silicon hydrogen group can react with the hydroxyl group on the fiber surface treated with sodium hydroxide solution to form a stable siloxane bond and attach to the fiber surface, thereby further increasing the roughness of the fiber surface and promoting the combination of the fiber and cement particles. It can be understood that by using an appropriate amount of co-solvent, i.e., ethanol, it can help disperse γ-aminopropyl triethoxysilane and adjust the reaction rate. For example, increasing the proportion of ethanol can slow down the hydrolysis rate, and vice versa.

[0043] Preferably, in the γ-aminopropyltriethoxysilane: the γ-aminopropyltriethoxysilane content is ≥96%, the water content is ≤0.5%, and the specific gravity at 25°C is 0.9390-0.9430 g / ml.

[0044] Preferably, in step S3, solution c is treated by stirring for 15 minutes, standing for 15 minutes and cycling twice to better promote sufficient mixing and dispersion of reactants in solution c, optimize the mass transfer process, and avoid possible material structure damage caused by continuous stirring.

[0045] Specifically, in step S4, water-based epoxy resin is a resin with excellent corrosion resistance and good bonding performance, and its molecular structure is compact, and it has very strong cohesion. After the water-based epoxy resin is dried and shaped, it can wrap the fiber well. Therefore, in the mixing process of each raw material in the autoclaved aerated concrete board, the modified fiber is more evenly dispersed in the mixture to be poured, and the unmodified fiber is easily agglomerated and floated, resulting in poor dispersion in the material. In addition, because the water-based epoxy resin is softened by heat and / or alkali, in the pouring and curing process of the autoclaved aerated concrete board, the ambient temperature is relatively high and the whole is alkaline in the concrete slurry, and the water-based epoxy resin can be softened, and the fiber wrapped by it is exposed and contacted with concrete particles, and the softened water-based epoxy resin can be evenly dispersed in the autoclaved aerated concrete slab body, and at the same time, the polar hydroxyl and ether bond contained in its epoxy resin molecular chain can be combined with concrete particles to form a strong chemical bond, thereby increasing the adhesion between the material and the concrete, and significantly improving the finished autoclaved aerated concrete size.

[0046] Preferably, the water-based epoxy resin has: a solid content of ≥50%, a water content of ≤30%, and an epoxy value of 0.3-0.5 meq / 100g.

[0047] In particular, the drying method includes air drying at room temperature, forced ventilation drying or heating drying to achieve product shaping, wherein the specific drying method can be selected according to actual production conditions, so as to enable subsequent cutting processing. It should be noted that in other embodiments, other types of drying methods can also be used, which are not specifically limited here, but these solutions are all within the protection scope of the present invention.

[0048] Preferably, the length of the modified fiber fixed by the water-based epoxy resin can be conveniently controlled so that the final length of the modified fiber is 0.1-20 mm, thereby effectively improving its fluidity in the concrete slurry and making it evenly distributed in the board; secondly, it avoids the phenomenon that longer fibers are pulled out or broken during the cutting process, resulting in uneven incisions, increased burrs, and other factors that affect the quality of the cutting surface.

[0049] Preferably, the ethanol used for washing in step S2 and the ethanol used for preparing the solution in steps S3 and S4 are all anhydrous ethanol, and wherein: the mass fraction of ethanol is ≥99.5%, the mass fraction of water is ≤0.5%, and the density at 20°C is 0.789-0.791%.

[0050] It should be noted that the fiber in the preparation method includes at least one of basalt fiber and PTFE (polytetrafluoroethylene) fiber. It is understandable that when the fiber is only PTFE fiber, due to the alkali resistance of PTFE fiber and the absence of hydroxyl groups in its structure, steps S1 and S3 can be omitted, and only steps S2 and S4 are performed, that is, after removing the static electricity on the surface of the PTFE fiber, it is wrapped with a water-based epoxy resin to prevent it from agglomerating into flocculation, thereby helping to improve the performance of the autoclaved aerated concrete board prepared subsequently.

[0051] In an optional embodiment, the PTFE fiber is pre-modified by a filling modification method, and the filling material is glass fiber. Thereafter, the pre-modified PTFE fiber is processed by the preparation method to obtain a finished modified PTFE fiber, thereby further improving the performance of the autoclaved aerated concrete board by increasing the friction coefficient of the PTFE fiber.

[0052] The preparation method of the embodiment of the present invention generally includes: soaking the fiber in a sodium hydroxide solution; then, washing it with deionized water and ethanol for multiple times; adding the washed solid and γ-aminopropyltriethoxysilane to the mixed solution of ethanol and deionized water to obtain a mixed solution, stirring the solution, standing, filtering, and separating to obtain a solid; adding the solid to a water-based epoxy resin, stirring evenly, drying and shaping, cutting into short fibers, and finally obtaining modified fibers. By subjecting the fiber to a surface treatment including alkali soaking, washing, and coupling, the surface roughness of the fiber is significantly improved and its surface impurities and charges are removed, thereby facilitating its contact with concrete particles. Secondly, the surface-treated fiber is coated with a water-based epoxy resin, thereby effectively improving the dispersibility of the modified fiber in the blank and avoiding agglomeration into flocs. At the same time, the water-based epoxy resin can react with concrete particles to further enhance the performance of the concrete board and improve the size of the finished concrete board.

[0053] The present invention also provides an application of modified fibers in concrete products, wherein the modified fibers are used to completely replace steel bars and unmodified fibers to prepare autoclaved aerated concrete panels, wherein the autoclaved aerated concrete panels are mainly non-load-bearing walls of buildings, including interior walls and exterior walls.

[0054] It can be understood that in the preparation process of ordinary concrete products for other purposes, a mixing process is required. At the same time, the alkalinity of concrete slurry is one of its important chemical properties. Therefore, the modified fiber prepared by the preparation method is not limited to the anti-cracking application of autoclaved aerated concrete panels, but is also suitable for anti-cracking treatment application scenarios of various ordinary concrete products. Among them, the modified fiber is used as an anti-cracking treatment additive, which is suitable for but not limited to the following concrete types and related engineering application scenarios: building concrete, lightweight concrete, municipal asphalt concrete, and high-strength concrete for bridges. In addition, the modified fiber can effectively improve the anti-cracking performance of the above-mentioned concrete materials, thereby improving the quality of the project, reducing maintenance costs, and meeting the special needs of different construction environments.

[0055] In order to further illustrate the present invention, commercially available basalt fibers are used to describe in detail the preparation method of the modified fibers provided by the present invention in combination with comparative examples and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] S1: Soak the fiber in a 5% sodium hydroxide solution for 1.5 h to obtain solution a;

[0058] S2: Filter the solution a to separate the solid a, and wash the solid a multiple times with deionized water and ethanol;

[0059] S3: preparing a mixed solution b of ethanol and deionized water, wherein the volume ratio of the two is 7.5:2.5; adding fixed a and γ-aminopropyltriethoxysilane to the solution b, wherein the mass ratio of the two is maintained at 1.2:1.6, thereby obtaining a solution c; stirring the solution c, standing it for 1 hour, and then filtering and separating to obtain a solid b;

[0060] S4: Add solid b into the water-based epoxy resin and control the mass ratio of the two to be 1.2:1.6. Stir the mixture evenly and dry it to set it. Then cut it into short fibers of uniform specifications to finally obtain modified fibers.

[0061] The modified fiber is used as raw material, and raw materials mainly composed of siliceous material and calcareous material are added, and a gas generating agent is added, and an autoclaved aerated concrete board is made through processes such as casting, pre-curing, cutting, and steam curing.

[0062] Example 2

[0063] S1: Soak the fiber in a 10% sodium hydroxide solution for 1.5 h to obtain solution a;

[0064] S2: Filter the solution a to separate the solid a, and wash the solid a multiple times with deionized water and ethanol;

[0065] S3: preparing a mixed solution b of ethanol and deionized water, wherein the volume ratio of the two is 8:2; adding fixed a and γ-aminopropyltriethoxysilane to the solution b, wherein the mass ratio of the two is maintained at 1:2, thereby obtaining a solution c; stirring the solution c, standing it for 1 hour, and then filtering and separating to obtain a solid b;

[0066] S4: Add solid b into the water-based epoxy resin and control the mass ratio of the two to be 1:2. Stir the mixture evenly and let it dry to set. Then cut it into short fibers of uniform specifications to finally obtain modified fibers.

[0067] The modified fiber is used as raw material, and raw materials mainly composed of siliceous material and calcareous material are added, and a gas generating agent is added, and an autoclaved aerated concrete board is made through processes such as casting, pre-curing, cutting, and steam curing.

[0068] Example 3

[0069] S1: Soak the fiber in 15% sodium hydroxide solution for 1 h to obtain solution a;

[0070] S2: Filter the solution a to separate the solid a, and wash the solid a multiple times with deionized water and ethanol;

[0071] S3: preparing a mixed solution b of ethanol and deionized water, wherein the volume ratio of the two is 8.5:1.5; adding fixed a and γ-aminopropyltriethoxysilane to the solution b, wherein the mass ratio of the two is maintained at 0.8:2.4, thereby obtaining a solution c; stirring the solution c, standing it for 1 hour, and then filtering and separating to obtain a solid b;

[0072] S4: Add solid b into the water-based epoxy resin and control the mass ratio of the two to be 0.8:2.4. Stir the mixture evenly and dry it to set it, then cut it into short fibers of uniform specifications to finally obtain modified fibers.

[0073] The modified fiber is used as raw material, and raw materials mainly composed of siliceous material and calcareous material are added, and a gas generating agent is added, and an autoclaved aerated concrete board is made through processes such as casting, pre-curing, cutting, and steam curing.

[0074] Comparative Example 1

[0075] Unmodified fibers are used as raw materials, and raw materials mainly composed of siliceous materials and calcareous materials are added, and a gas-generating agent is added. The autoclaved aerated concrete board is made through processes such as casting, pre-curing, cutting, and steam curing.

[0076] The fibers and autoclaved aerated concrete board products in Examples 1-3 and Comparative Example 1 were subjected to a number of tests, including:

[0077] The fiber microstructures in Example 2 and Comparative Example 1 were photographed and observed, and their performance was subjected to standardized tests. The test results are shown in Figure 3 From Table 1, it can be clearly seen that after the fiber is modified, the surface changes from smooth to rough, and the silane coupling agent is connected to the fiber surface, so that the fiber surface forms branched and granular substances, thereby effectively increasing the adhesion between the fiber and the concrete particles; the density, tensile strength and elongation at break of the modified fiber are slightly smaller than those of the unmodified fiber, while the elastic modulus is greater than that of the unmodified fiber, indicating that the properties of the fiber itself have not changed significantly, and it can continue to be used as a raw material for autoclaved aerated concrete slabs to replace steel bars.

[0078] Table 1 Fiber performance test results

[0079]

[0080] In the high standard test of bending resistance meeting 2.5 times of its own weight, the length of a single board of the finished autoclaved aerated concrete board in Examples 1-3 is ≤3.0m, while the length of a single board of the finished autoclaved aerated concrete board in Comparative Example 1 is ≤1.5m, indicating that the modified fiber prepared by the preparation method can effectively improve the size of the finished autoclaved aerated concrete board.

[0081] The finished autoclaved aerated concrete boards of Examples 1-3 and Comparative Example 1 were cut and tested for performance with the same size (1800mm×600mm×100mm). The test results are shown in Table 2. It can be seen that the single boards obtained by the same autoclaved aerated concrete board preparation method have similar bulk densities of the boards of Comparative Example 1 and Examples 1-3 at the same finished product size, with no obvious difference. However, the bending resistance of the boards prepared by the modified fibers of Examples 1-3 can reach the standard of 2.5 times of their own weight, while the bending resistance of the boards prepared by the fibers of Comparative Example 1 can only reach the bending load of 2 times of their own weight. Secondly, the compressive strength of the boards of Examples 1-3 increases with the increase of the content of waterborne epoxy resin in the modified fibers, and is greater than the compressive strength of the boards of Comparative Example 1.

[0082] Table 2 Autoclaved aerated concrete board performance test results

[0083]

[0084] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0085] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0086] In this patent, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, the elements defined by the sentence "includes..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Those skilled in the art will readily understand that the above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a modified fiber, characterized in that: The steps include: S1: soaking the fiber in a 5-15% sodium hydroxide solution for 0.5-2h to obtain solution a; S2: Filter the solution a to separate the solid a, and wash the solid a multiple times with deionized water and ethanol; S3: preparing a mixed solution b of ethanol and deionized water, wherein the volume ratio of the two is between 7.5:2.5 and 8.5:1.5; adding a and γ-aminopropyltriethoxysilane to the solution b, wherein the mass ratio of the two is maintained in the range of 1.2:1.6 to 0.8:2.4, thereby obtaining a solution c, stirring the solution c, standing it for 1 hour, and then filtering and separating to obtain a solid b; S4: adding solid b into waterborne epoxy resin and controlling the mass ratio of the two within the range of 1.2:1.6 to 0.8:2.4, stirring the mixture evenly and drying it to set it, and then cutting it into short fibers of uniform specifications to finally obtain modified fibers.

2. The preparation method according to claim 1, characterized in that: In step S1, the temperature range of the sodium hydroxide solution is preferably 20°C-40°C; The sodium hydroxide solution is prepared by preparing industrial sodium hydroxide solid, wherein the industrial sodium hydroxide comprises: NaOH≥90%, Na2CO3≤0.65, NaCl≤0.05, and Fe2O3≤0.

008.

3. The preparation method according to claim 1, characterized in that: In step S2, the washing times are at least three times.

4. The preparation method according to claim 1, characterized in that: In step S3, solution c is treated by stirring for 15 minutes, standing for 15 minutes, and circulating twice.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The γ-aminopropyltriethoxysilane has the following contents: γ-aminopropyltriethoxysilane content is ≥96%, water content is ≤0.5%, and specific gravity at 25°C is 0.9390-0.9430 g / ml.

6. The preparation method according to any one of claims 1 to 4, characterized in that: The air-drying method includes air-drying at room temperature, forced ventilation drying or heating drying.

7. The preparation method according to any one of claims 1 to 4, characterized in that: The waterborne epoxy resin has a solid content of ≥50%, a water content of ≤30%, and an epoxy value of 0.3-0.5 meq / 100g.

8. The preparation method according to any one of claims 1 to 4, characterized in that: The ethanol used for washing in step S2 and the ethanol used for preparing the solution in steps S3 and S4 are all anhydrous ethanol, wherein: the mass fraction of ethanol is ≥99.5%, the mass fraction of water is ≤0.5%, and the density at 20°C is 0.789-0.791%.

9. The preparation method according to any one of claims 1 to 4, characterized in that: The fiber in the preparation method comprises at least one of basalt fiber and PTFE fiber; The length of the modified fiber is 0.1-20 mm.

10. Application of modified fiber in concrete products, characterized in that: The modified fiber is prepared according to the preparation method described in any one of claims 1 to 9, and the modified fiber is used to completely replace the steel bars and unmodified fibers to prepare the autoclaved aerated concrete board; The autoclaved aerated concrete slabs are mainly non-load-bearing walls of buildings, including interior walls and exterior walls.

11. The use of the modified fiber in concrete products according to claim 10, characterized in that: The modified fiber is used as an anti-cracking treatment additive and is suitable for, but not limited to, building concrete, lightweight concrete, municipal asphalt concrete, and high-strength concrete for bridges.

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