Preparation method of alkali-resistant basalt fiber for cement-based cementitious materials

Abstract

The application discloses a preparation method of alkali-resistant basalt fiber for cement-based cementitious materials, which comprises the following steps: mixing basalt and additives by ball milling to obtain basalt fiber raw materials; gradually heating the basalt fiber raw materials to 1350-1600 DEG C, and then homogenizing for 5-10 hours to obtain basalt melt; quenching the basalt melt to obtain basalt glass; drawing hot fibers from the basalt glass under the condition of 1250-1450 DEG C, and modifying the hot fibers to obtain alkali-resistant basalt fiber, wherein the modification is that alkali-resistant slurry is coated on the hot fibers during the drawing process. The application can improve the alkali resistance of the basalt fiber, and realizes the effect of long-term performance stability of the basalt fiber reinforced cement-based material.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a method for preparing alkali-resistant basalt fibers for cement-based cementitious materials. Background Technology

[0002] Continuous basalt fiber is an environmentally friendly material, extruded from molten volcanic rock at 1400-1500℃. Due to its advantages such as good modulus, high strength, large failure strain, good stability, and resistance to thermal and chemical corrosion, basalt fiber is considered a superior reinforcing material for cementitious matrices. Basalt fiber does not react chemically with other substances, making it an eco-friendly material. However, the main component of the basalt fiber network skeleton is Si-O bonds, which can still react with OH- ions in alkaline environments. Therefore, there is an urgent need to develop an alkali-resistant basalt fiber to improve the degradation of the mechanical properties of basalt fiber and its reinforced cementitious products. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing alkali-resistant basalt fibers for cement-based cementitious materials, so as to improve the alkali resistance of basalt fibers in cement-based cementitious materials.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing alkali-resistant basalt fiber for cementitious materials includes the following steps:

[0006] S1. Basalt and additives are mixed by ball milling to obtain basalt fiber raw material;

[0007] S2. Gradually heat the basalt fiber raw material to 1350-1600℃, and then homogenize it for 5-10 hours to obtain basalt melt.

[0008] S3. Quench the basalt melt to obtain basalt glass;

[0009] S4. Basalt glass is drawn into thermal fibers at 1250-1450℃, and the thermal fibers are modified to obtain alkali-resistant basalt fibers. The modification is to coat the thermal fibers with alkali-resistant slurry during the drawing process.

[0010] In step S4, during the drawing process, an alkali-resistant slurry is coated onto the hot fiber through a container connected to a liquid funnel on the drawing machine.

[0011] Preferably, in step S1, basalt and additives are mixed by ball milling and then separated from the milling balls through a sieve plate to obtain basalt fiber raw material;

[0012] Preferably, in step S3, the basalt melt is quickly poured onto a heat-resistant steel plate and quenched to obtain basalt glass.

[0013] Preferably, in step S4, the basalt glass is drawn into wire using a platinum-rhodium alloy spindle at 1320°C.

[0014] Furthermore, the alkali-resistant slurry is obtained by loading nano-TiO2 and nano-Ta2O5 onto montmorillonite, and the preparation method includes the following steps:

[0015] Step A: Slowly add 10 mL of 6 mol / L HCl to 2.5 mL of 0.08 mol / L TiCl4 solution to obtain the first solution. Then slowly add distilled water to dilute to 100 mL of the first solution. Stir thoroughly until the first solution is clear. Then add 5 mol / L ammonia to adjust the pH of the first solution to 8-9. The volume ratio of ammonia to the first solution is 1:1. After aging at room temperature for 3 hours, the nano-TiO2 precursor solution is obtained.

[0016] Step B: Add 8g of tantalum ethoxide to 20mL of ethanol to prepare a tantalum ethoxide-ethanol solution. Then slowly add distilled water to dilute the volume of the tantalum ethoxide-ethanol solution to 100mL. Stir thoroughly and then add 5mol / L ammonia water to adjust the pH value of the tantalum ethoxide-ethanol solution to 8-9. The volume ratio of ammonia water to tantalum ethoxide-ethanol solution is 1:1. Heat to 80℃-85℃ and keep warm for 30min to obtain the nano Ta2O5 precursor solution.

[0017] Step C: Sodium-based montmorillonite is treated with ultrasound in distilled water to obtain a montmorillonite suspension with a solid content of 20 wt%.

[0018] Step D: Following the formula of 5 mmol Ti per 1g montmorillonite 4+ and 5mmol Ta 5+ The amount of nano-TiO2 precursor solution and nano-Ta2O5 precursor solution was added dropwise to the montmorillonite suspension and stirred evenly. The pH was adjusted to 5-7 using boric acid to obtain an alkali-resistant slurry. The final concentration of montmorillonite in the alkali-resistant slurry was 4 g / L.

[0019] Furthermore, the additives include rutile, barite, and zircon.

[0020] Furthermore, the basalt fiber raw material comprises the following components by weight percentage:

[0021]

[0022] Furthermore, the main component of the rutile is TiO2, and the content of TiO2 is ≥95wt%; the main component of the barite is BaSO4, and the content of BaSO4 is 92-98wt%; the zircon contains the following components by weight percentage: ZrO2: 62-67wt%, SiO2: 28-32wt%.

[0023] Furthermore, the basalt contains the following minerals by weight percentage: SiO2: 45-55 wt%, Al2O3: 12-15 wt%, Fe2O3: 9.5-13 wt%, TiO2: 2.0-3.0 wt%, CaO: 5.0-8.5 wt%, MgO: 5.0-8.5 wt%, K2O: 1.5-3.5 wt%, Na2O: 3.5-4.5 wt%.

[0024] Furthermore, the average particle size of the basalt fiber raw material is 65-80 μm.

[0025] Further, in step S2, the preferred method is to place the basalt fiber raw material in a high-temperature muffle furnace and heat it to 1000°C at 250°C / h, then further heat it to 1550°C at 30°C / h, and then homogenize it at 1550°C for 6 hours to obtain basalt melt.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The zircon used in this invention contains Zr, and the rutile contains Ti, while Zr... 4+ Ti 4+ and Si 4+ The radii are similar, Zr 4+ Ti 4+ It can form a web-like structure [ZrO4]. 4+ [TiO4] 4+ The form of replacing part of Si 4+ This connects the fragmented silicon-oxygen network. [ZrO4] 4+ [TiO4] 4+ and [SiO4] 4+ The formation of a titanium silicate mixed framework enhances the network structure and improves the alkali resistance and tensile strength of basalt fibers. Barite, a barium-containing sulfate mineral, contains BaSO4, a sparingly soluble compound that resists alkali corrosion. Therefore, the synergistic effect of zircon, rutile, and barite significantly improves the fiber's resistance to alkali corrosion.

[0028] 2. When basalt fibers are used in cementitious materials, OH - The slow diffusion into the fiber interior disrupts the silicon-aluminum network structure, while Si and Al diffuse into the solution as soluble ions, and simultaneously, Mg inside the fiber...2+ Fe 3+ Ca 2+ Zr 4+ and Ti 4+ It slowly diffuses to the surface, generating alkali-resistant compounds that form a protective layer, mitigating further damage to the fibers in alkaline solutions. Zr... 4+ and Ti 4+ The protective layer produced by the combination is compared to that of Zr alone. 4+ or Ti 4+ The resulting protective layer has better density, which can significantly improve the alkali resistance of basalt fibers.

[0029] 3. Unlike other studies on modified basalt fibers, this invention uses basalt fiber as a substrate, eliminating the need for cumbersome steps and achieving surface modification in a one-step process. Due to the relatively high temperature immediately after fiber drawing, montmorillonite loaded with nano-TiO2 and nano-Ta2O5 easily deposits onto the basalt fiber. Furthermore, this alkali-resistant slurry exhibits good dispersibility, enabling uniform coating on the basalt fiber surface. The basalt fiber reacts with the silanol groups of montmorillonite to form new Si-O-Si bonds, thereby improving the alkali resistance and tensile strength of the basalt fiber.

[0030] Both TiO2 and Ta2O5 are highly stable under both acidic and alkaline conditions, preventing the intrusion of alkaline solutions and thus inhibiting fiber dissolution and damage. Simultaneously, montmorillonite coated with nano-TiO2 and nano-Ta2O5 possesses a large specific surface area, and the addition of Ta2O5 increases the number of -OH groups on the TiO2 coating surface. These -OH groups interact with the OH groups in cement-based cementitious materials. - A reaction occurs, forming a negative charge on the coating surface, increasing the adsorption capacity of montmorillonite and allowing Ca to... 2+ Ba 2+ The deposits on the coating surface form a denser protective layer, limiting the entry of corrosive alkaline media into the fibers. Attached Figure Description

[0031] Figure 1 This is a microstructure diagram of the alkali-resistant basalt fiber in Example 1 of the present invention.

[0032] Figure 2 This is a microstructure diagram of ordinary basalt fiber, which is Comparative Example 1 of the present invention. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0034] In various embodiments of the present invention, the preparation method of alkali-resistant basalt fiber for cement-based cementitious materials includes the following steps:

[0035] S1. Basalt and additives are mixed by ball milling, and then separated from the milling balls through a sieve plate to obtain basalt fiber raw material;

[0036] S2. The basalt fiber raw material is placed in a high-temperature muffle furnace and heated to 1000℃ at 250℃ / h, and then further heated to 1550℃ at 30℃ / h. It is then homogenized at 1550℃ for 6 hours to obtain basalt melt.

[0037] S3. Quickly pour the basalt melt onto a heat-resistant steel plate and quench it to obtain basalt glass;

[0038] S4. Basalt glass is drawn into thermal fibers using a platinum-rhodium alloy spinneret at 1320℃, and an alkali-resistant slurry is coated onto the thermal fibers during the drawing process to obtain alkali-resistant basalt fibers.

[0039] Example 1

[0040] As a preferred embodiment of the present invention, this embodiment provides alkali-resistant basalt fiber for cementitious materials. In this embodiment, the basalt fiber raw material includes the following components by weight percentage:

[0041]

[0042] Example 2

[0043] As a preferred embodiment of the present invention, this embodiment provides alkali-resistant basalt fiber for cementitious materials. In this embodiment, the basalt fiber raw material includes the following components by weight percentage:

[0044]

[0045] Example 3

[0046] As a preferred embodiment of the present invention, this embodiment provides alkali-resistant basalt fiber for cementitious materials. In this embodiment, the basalt fiber raw material includes the following components by weight percentage:

[0047]

[0048] Example 4

[0049] As a preferred embodiment of the present invention, this embodiment provides alkali-resistant basalt fiber for cementitious materials. In this embodiment, the basalt fiber raw material includes the following components by weight percentage:

[0050]

[0051] Comparative Example 1

[0052] The basalt fiber used in this comparative example is ordinary basalt fiber, sourced from Sichuan Aerospace Tuoxin Basalt Industry Co., Ltd.

[0053] Comparative Example 2

[0054] The basalt fiber in this comparative example uses the same basalt fiber raw material as in Example 1, but the alkali-resistant slurry is not added during the drawing process.

[0055] Basalt fibers from each embodiment and comparative example were placed in a NaOH solution at 80°C and 5 wt% by mass for accelerated aging. After 6 h, 24 h, and 96 h, they were rinsed with deionized water and kept at 105°C for 1 h in a drying oven. They were then removed and placed in a desiccator to cool to room temperature to measure their weight loss and tensile breaking strength. The test results are shown in Table 1 below.

[0056] Table 1

[0057]

[0058] As shown in Table 1, after soaking in a 5 wt% NaOH solution for 24 hours, the ordinary basalt fiber in Comparative Example 1 was completely eroded and the fiber broke. The strength retention rate of Examples 1-4 at each time period was significantly greater than that of Comparative Examples 1-2. Furthermore, after 96 hours of accelerated aging, Examples 1-4 and Comparative Example 2 still retained a certain residual strength. Compared with Comparative Example 1, Examples 1-4 demonstrate that the alkali-resistant basalt fiber of the present invention can effectively improve the alkali resistance strength of basalt fiber and reduce alkali loss. Compared with Comparative Example 2, Example 1 demonstrates that the alkali-resistant slurry can further enhance the alkali resistance of basalt fiber.

[0059] Figure 1 and Figure 2 The images show the microstructures of the alkali-resistant basalt fiber from Example 1 after accelerated aging for 6 hours and the ordinary basalt fiber from Comparative Example 1 after accelerated aging for 6 hours. In Example 1, a few pits appeared on the fiber surface after 6 hours of accelerated aging, while in Comparative Example 1, the fiber surface showed severe damage. Therefore, the alkali-resistant basalt fiber of the present invention can effectively improve the alkali resistance of basalt fiber.

[0060] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing alkali-resistant basalt fiber for cementitious materials, characterized in that, Includes the following steps: S1. Basalt and additives are mixed by ball milling to obtain basalt fiber raw material; S2. Gradually heat the basalt fiber raw material to 1350-1600℃, and then homogenize it for 5-10 hours to obtain basalt melt. S3. Quench the basalt melt to obtain basalt glass; S4. Basalt glass is drawn into thermal fibers at 1250-1450℃, and the thermal fibers are modified to obtain alkali-resistant basalt fibers. The modification is to coat the thermal fibers with alkali-resistant slurry during the drawing process. The alkali-resistant slurry is obtained by loading nano-TiO2 and nano-Ta2O5 onto montmorillonite. The basalt fiber raw material comprises the following components by weight percentage: Basalt 55-80 wt% Rutile 5-10 wt% 3-5 wt% barite; Zircon 12-30wt%.

2. The method for preparing alkali-resistant basalt fiber for cementitious materials according to claim 1, characterized in that, The preparation method of the alkali-resistant slurry includes the following steps: Step A: Slowly add 10 mL of 6 mol / L HCl to 2.5 mL of 0.08 mol / L TiCl4 solution to obtain the first solution. Then slowly add distilled water to dilute to 100 mL of the first solution. Stir thoroughly until the first solution is clear. Then add 5 mol / L ammonia to adjust the pH of the first solution to 8-9. The volume ratio of ammonia to the first solution is 1:

1. After aging at room temperature for 3 h, the nano-TiO2 precursor solution is obtained. Step B: Add 8g of tantalum ethoxide to 20mL of ethanol to prepare a tantalum ethoxide-ethanol solution. Then slowly add distilled water to dilute the volume of the tantalum ethoxide-ethanol solution to 100mL. Stir thoroughly and then add 5mol / L ammonia water to adjust the pH value of the tantalum ethoxide-ethanol solution to 8-9. The volume ratio of ammonia water to tantalum ethoxide-ethanol solution is 1:

1. Heat to 80℃-85℃ and keep warm for 30min to obtain the nano Ta2O5 precursor solution. Step C: Sodium-based montmorillonite was ultrasonically treated in distilled water to obtain a montmorillonite suspension with a solid content of 20 wt%. Step D: Calculate the dosage based on 5 mmol Ti per 1 g montmorillonite. 4+ and 5 mmol Ta 5+ The amount of nano-TiO2 precursor solution and nano-Ta2O5 precursor solution was added dropwise to the montmorillonite suspension and stirred evenly. The pH was adjusted to 5-7 using boric acid to obtain an alkali-resistant slurry. The final concentration of montmorillonite in the alkali-resistant slurry was 4 g / L.

3. The method for preparing alkali-resistant basalt fiber for cementitious materials according to claim 1, characterized in that, The additives include rutile, barite, and zircon.

4. The method for preparing alkali-resistant basalt fiber for cementitious materials according to claim 3, characterized in that, The main component of the rutile is TiO2, with a TiO2 content ≥95wt%; the main component of the barite is BaSO4, with a BaSO4 content of 92-98wt%; the zircon contains the following components by weight percentage: ZrO2: 62-67wt%, SiO2: 28-32wt%.

5. A method for preparing alkali-resistant basalt fiber for cementitious materials according to claim 1, characterized in that, The basalt contains the following minerals by weight percentage: SiO2: 45-55wt%, Al2O3: 12-15wt%, Fe2O3: 9.5-13wt%, TiO2: 2.0-3.0wt%, CaO: 5.0-8.5wt%, MgO: 5.0-8.5wt%, K2O: 1.5-3.5wt%, Na2O: 3.5-4.5wt%.

6. The method for preparing alkali-resistant basalt fiber for cementitious materials according to claim 1, characterized in that, The average particle size of the basalt fiber raw material is 65-80 μm.

7. The method for preparing alkali-resistant basalt fiber for cementitious materials according to claim 1, characterized in that, S2 involves placing basalt fiber raw material in a high-temperature muffle furnace and heating it to 1000°C at 250°C / h, then further heating it to 1550°C at 30°C / h, and then homogenizing it at 1550°C for 6 hours to obtain basalt melt.

Images