A carbon fiber dispersion paste, its preparation method and application

Abstract

The invention discloses a carbon fiber dispersion paste, which comprises the following components by weight: 100 parts of powdered mineral, 10-20 parts of water, 0.5-1.5 parts of polyethylene glycol, 0.5-1.5 parts of a water reducer and 3-8 parts of carbon fiber; a preparation method comprises the following steps: mixing and stirring the powdered mineral, water, polyethylene glycol and a water reducer to form a plastic paste; adding carbon fiber and stirring at a low speed for 2-4 minutes and stirring at a high speed for 3-6 minutes to obtain a uniformly dispersed carbon fiber dispersion paste; the invention uses the powdered mineral paste as a dispersant main body, which not only realizes efficient dispersion of carbon fiber, but also obtains a dispersion system highly compatible with a cement matrix; a calcium carbonate component in the powdered mineral can also be used as a filling material for composite reinforcement with carbon fiber, and the problem of difficulty in using carbon fiber in cement material is perfectly solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of building materials, and particularly relates to a carbon fiber dispersion paste, a preparation method thereof, and an application thereof. Background Art

[0002] As is well known, carbon fiber has excellent chemical stability and can avoid corrosion in most extreme environments. In addition, carbon fiber also has the advantages of light weight, high strength, and high elastic modulus. In recent years, with the improvement of carbon fiber production technology and the expansion of production scale, the cost of carbon fiber has been greatly reduced, so it is expected to be widely used in the concrete field.

[0003] Due to van der Waals forces and the hydrophobicity of the fibers, carbon fibers tend to be unevenly distributed in the cementitious material, which leads to a serious decline in mechanical properties. In addition, carbon fibers often appear in bundles. If they cannot be dispersed into single carbon fibers, they are prone to agglomeration during the mixing process, which not only reduces the use efficiency but also easily causes local defects. Therefore, the dispersion method of carbon fiber is the primary problem in its application in concrete. CN115974452A discloses a CFRC carbon fiber additive, a preparation method thereof, and an application process, which uses carboxymethyl cellulose, silica fume, tributyl phosphate, etc. to prepare carbon fiber dispersion material, simplifying the construction process in practical applications. CN116043521A discloses a preparation method and a dispersion system of aqueous carbon fiber, which enhances its hydrophilicity through surface modification of carbon fiber, making it easier to disperse in water. CN112537924A discloses a carbon fiber concrete curbstone and a preparation method thereof, which mixes carbon fiber, methyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose, silica fume, water and other substances and then performs ultrasonic dispersion to obtain a uniformly dispersed carbon fiber mixed solution.

[0004] Although the current carbon fiber dispersion methods have been gradually improved, the difficulty of using carbon fiber has been reduced and the process has been simplified, there are still some problems to be solved. First of all, most studies introduce a large amount of polymers during the dispersion process, which have good compatibility with carbon fibers, but the compatibility with the cement matrix cannot be determined; secondly, the method of surface modification of carbon fibers is still relatively complex, and the material and time costs consumed in the pretreatment process are far higher than the casting and molding process, and it is difficult to be applied on a large scale; finally, the energy consumption of conventional fiber dispersion machines or ultrasonic dispersion methods is relatively high. On the one hand, it is not economically applicable, and on the other hand, high energy will cause carbon fibers to break and fracture, affecting the actual use. Summary of the Invention

[0005] The object of the present invention is to provide a carbon fiber dispersion paste, its preparation method and application. By using a powder mineral paste as the main dispersant, not only the efficient dispersion of carbon fibers is achieved, but also a dispersion system highly compatible with the cement matrix is obtained. The calcium carbonate component in the powder mineral can also be used as a filling material to be compounded and reinforced with carbon fibers, perfectly solving the problem of the difficult use of carbon fibers in cement materials.

[0006] To achieve the above object, the following technical solutions are adopted:

[0007] A carbon fiber dispersion paste, the composition of which is as follows by weight parts:

[0008] 100 parts of powder mineral, 10 - 20 parts of water, 0.5 - 1.5 parts of polyethylene glycol, 0.5 - 1.5 parts of water reducing agent, 3 - 8 parts of carbon fiber.

[0009] According to the above scheme, the powder mineral is stone powder or filter press soil, the CaCO3 content is ≥ 50wt%, and the median particle size is 5 - 80μm.

[0010] According to the above scheme, the molecular weight of the polyethylene glycol is 19000 - 21000.

[0011] According to the above scheme, the water reducing agent is lignosulfonate, naphthalene series or polycarboxylic acid type water reducing agent.

[0012] According to the above scheme, the length of the carbon fiber is 1 - 15mm.

[0013] The preparation method of the above carbon fiber dispersion paste includes the following steps:

[0014] (1) Mix the powder mineral, water, polyethylene glycol and water reducing agent and stir until a plastic paste is formed;

[0015] (2) Add carbon fiber and stir at low speed for 2 - 4min and at high speed for 3 - 6min to obtain a uniformly dispersed carbon fiber dispersion paste.

[0016] According to the above scheme, in step 2, the rotation speed of the low - speed stirring is 100 - 155rpm, and the rotation speed of the high - speed stirring is 235 - 300rpm.

[0017] The application of the above carbon fiber dispersion paste in cementitious materials.

[0018] According to the above scheme, it includes dry - mixing the cementitious material and the carbon fiber dispersion paste for 5 - 8min, and then adding water and continuing to stir for 3 - 5min until a uniform slurry state is obtained.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] Compared with the conventional polymer solution dispersion matrix, the calcium carbonate paste is highly compatible with the cement system, and its influence on the cement concrete matrix is beneficial and known. It can not only optimize the particle gradation as a filler, but also serve as a nucleation site for calcium silicate hydrate, reduce the nucleation barrier, and accelerate cement hydration. Therefore, after the carbon fiber is dispersed in the calcium carbonate paste, the calcium carbonate particles attached to its surface play a surface modification role to a certain extent, improving the interfacial transition zone between the cement matrix and the carbon fiber and enhancing the bonding strength. In addition, the dispersion process of carbon fiber is similar to the mixing of cement concrete, only requiring normal-speed mixing, and it can maintain the dispersed state for a long time, making it extremely easy to achieve large-scale industrial application. Detailed implementation manners

[0021] The following examples further illustrate the technical solutions of the present invention, but do not limit the protection scope of the present invention.

[0022] The detailed implementation manners provide a carbon fiber dispersion paste, and its composition is as follows by weight parts:

[0023] 100 parts of powder mineral, 10 - 20 parts of water, 0.5 - 1.5 parts of polyethylene glycol, 0.5 - 1.5 parts of water reducer, and 3 - 8 parts of carbon fiber.

[0024] Specifically, the powder mineral is stone powder or filter press soil, with a CaCO3 content ≥ 50 wt%, and a median particle size of 5 - 80 μm.

[0025] Specifically, the polyethylene glycol is an analytical pure reagent with a molecular weight of 19000 - 21000.

[0026] Specifically, the water reducer is a lignosulfonate, naphthalene-based or polycarboxylic acid type water reducer.

[0027] Specifically, the length of the carbon fiber is 1 - 15 mm.

[0028] The detailed implementation manners also provide a preparation method of the above carbon fiber dispersion paste, including the following steps:

[0029] (1) Mix the powder mineral, water, polyethylene glycol, and water reducer and stir until a plastic paste is obtained;

[0030] (2) Add the carbon fiber and stir at low speed for 2 - 4 min and at high speed for 3 - 6 min to obtain a uniformly dispersed carbon fiber dispersion paste.

[0031] Specifically, in step (2), the rotation speed of the low-speed stirring is 100 - 155 rpm, and the rotation speed of the high-speed stirring is 235 - 300 rpm.

[0032] The specific implementation manner also provides the application of the above carbon fiber dispersion paste in cementitious materials; it includes dry-mixing the cementitious materials and the carbon fiber dispersion paste for 5 - 8 min, adding water and continuing to stir for 3 - 5 min until a uniform paste state is achieved.

[0033] Five groups of carbon fiber dispersion pastes with different ratios were designed, and the mass parts of each component are given in Table 1. Among them, the powder mineral is stone powder, the CaCO3 content of the stone powder is 98 wt%, the median particle size is 11 μm; the carbon fiber length is 6 mm; the molecular weight of polyethylene glycol is 20,000; the water reducer is a polycarboxylate-based high-performance water reducer.

[0034] Table 1 Mix ratio of carbon fiber dispersion paste

[0035] Number Stone powder Water Polyethylene glycol Carbon fiber Water reducing agent Example 1 100 12 0.6 3.8 1.5 Example 2 100 12 0.6 4.8 1.7 Example 3 100 15 1.0 5.5 1.2 Example 4 100 13 0.7 6.3 1.3 Example 5 100 20 1.5 7.9 0.8

[0036] In the specific embodiments, the specific preparation process of the carbon fiber dispersion paste is as follows:

[0037] Mix the stone powder, water, polyethylene glycol, and polycarboxylate-based high-performance water reducer, and stir at a low speed for 8 min to obtain a plastic paste A;

[0038] Stir the paste A at a low speed, add the carbon fiber to the stirring container, first stir at a low speed for 2 min, and then stir at a high speed for 5 min to obtain a uniformly dispersed carbon fiber dispersion paste.

[0039] Dry-mix the same amount of cementitious materials with the carbon fiber dispersion paste obtained from the above 5 groups of examples for 6 min, add water and continue to stir for 5 min until a uniform paste state is presented to obtain uniformly mixed carbon fiber-reinforced concrete.

[0040] Comparative Example 1

[0041] This comparative example has the same mix ratio as Example 1, the difference is that no carbon fiber is added, the purpose is to avoid the influence of stone powder on the strength of the system, and the application process is the same.

[0042] Comparative Example 2

[0043] This comparative example uses polyacrylamide as a dispersion aid to prepare a conventional carbon fiber dispersion liquid, where the carbon fiber dosage is the same as that in Example 1, and the application process is the same.

[0044] Comparative Example 3

[0045] This comparative example uses the same mass of carbon fiber as Example 1, the difference is that no pre-dispersion is carried out, and the application process is the same.

[0046] Table 2 Performance test results of Examples 1 - 5 and Comparative Examples 1 - 3

[0047]

[0048]

[0049] It can be seen from the results of Comparative Example 1 that the use of stone powder alone has limited influence on the strength of concrete. Therefore, the high flexural strength of Example 1 comes from the carbon fiber dispersion paste of the present invention. Compared with the conventional fiber dispersion liquid (Comparative Example 2) or the non-pre-dispersion group (Comparative Example 3), the carbon fiber dispersion paste of the present invention shows higher system compatibility. Due to the nucleation effect of stone powder, it can greatly improve the flexural and compressive strength of the specimens without affecting the working performance of the system. In addition, comparing Examples 1-5, when the carbon fiber content is less than 8%, the carbon fiber dispersion paste of the present invention shows good dispersion. As the carbon fiber content increases, the strength of the system increases linearly. To sum up, the carbon fiber dispersion paste of the present invention avoids the high-speed stirring required by the conventional polymer dispersion method, avoids the fragmentation and fracture of carbon fibers during the high-energy dispersion process, and the attachment of stone powder on the fiber surface is beneficial to the subsequent hydration of cement particles on the fiber surface, improves the interfacial transition zone of the fiber-cement aggregate, and improves the fiber use efficiency.

Claims

1. A carbon fiber dispersion paste, characterized in that The composition is as follows by weight parts: 100 parts of powder mineral, 10 - 20 parts of water, 0.5 - 1.5 parts of polyethylene glycol, 0.5 - 1.5 parts of water reducing agent, 3 - 8 parts of carbon fiber; The powder mineral is stone powder or filter press soil, with a CaCO3 content ≥ 50 wt%, and a median particle size of 5 - 80 μm; The molecular weight of the polyethylene glycol is 19000 - 21000; The water reducing agent is lignosulfonate, naphthalene - based or polycarboxylate water reducing agent; The length of the carbon fiber is 1 - 15 mm.

2. The preparation method of the carbon fiber dispersion paste according to claim 1, characterized in that It includes the following steps: (1) Mix and stir the powder mineral, water, polyethylene glycol, and water reducing agent until a plastic paste is obtained; (2) Add carbon fiber and stir at a low speed for 2 - 4 min, then stir at a high speed for 3 - 6 min to obtain a uniformly dispersed carbon fiber dispersion paste.

3. The preparation method of the carbon fiber dispersion paste according to claim 2, characterized in that In step (2), the rotation speed for low - speed stirring is 100 - 155 rpm, and the rotation speed for high - speed stirring is 235 - 300 rpm.

4. Application of the carbon fiber dispersion paste according to claim 1 in cementitious materials.

5. The application of the carbon fiber dispersion paste in the cementitious material according to claim 4, characterized in that It includes dry - mixing the cementitious materials and the carbon fiber dispersion paste for 5 - 8 min, and then adding water and continuing to stir for 3 - 5 min until a uniform slurry state is achieved.

Images