Cement-based composite material and preparation method thereof

Abstract

The invention discloses a cement-based composite material and a preparation method thereof, and relates to the technical field of composite materials, and the cement-based composite material comprises the following components in parts by mass: 400-500 parts of cement, 150-200 parts of water, 0.5-1.0 part of a water reducing agent and 0.12-1.2 parts of magnetic graphene; the invention also provides a preparation method of the cement-based composite material. The preparation method comprises the following steps: S1, preparing the components according to the amount; s2, uniformly mixing water, a water reducing agent and the magnetic graphene, and performing ultrasonic dispersion for 10-30 minutes to form a magnetic graphene dispersion liquid; and S3, uniformly mixing and stirring the magnetic graphene dispersion liquid obtained in S2 and cement, putting the mixture into a standard mold, and then putting the standard mold into a uniform magnetic field generator for directional treatment to obtain the cement-based composite material.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology, and more specifically to a cement-based composite material and its preparation method. Background Technology

[0002] Cement-based materials, as the most important inorganic cementitious materials in civil engineering, have advantages such as high compressive strength. However, their slow early strength development and high brittleness limit their application in some high-performance scenarios. In recent years, the rise and development of nanomaterials have provided new ideas for improving the performance of cement-based materials. Among them, graphene is considered an ideal nanofiller for improving the performance of cement-based materials due to its excellent mechanical properties, high specific surface area, and potential reinforcing effect. However, graphene nanosheets are prone to agglomeration in cement-based materials, making uniform dispersion difficult. Furthermore, their planar orientation in cement-based materials is spatially random, resulting in insufficient reinforcement efficiency and preventing the realization of directional and efficient reinforcement of cement-based materials.

[0003] To improve the dispersion and control the orientation of graphene, previous studies have attempted to achieve ordered arrangement of graphene in a cement matrix using external physical fields. Planar orientation of graphene oxide and thermally reduced graphene oxide in a cement matrix has been achieved by applying a magnetic field, significantly improving the flexural strength, flexural modulus, and dielectric constant of the specimens. However, these studies mostly focus on performance testing in a single direction, failing to systematically examine the performance differences of materials in different directions. In practical engineering, cement-based materials often face multi-directional forces or environmental effects in specific directions, exhibiting inherent anisotropic properties.

[0004] In the study "Influence of Magnetic Field Induction on Compressive Strength of Magnetic Graphene-Modified Cement Paste [J]" (Zheng Cheng, Wang Yinghao, Zhang Yizhou, et al. Journal of Composite Materials, 2024: 1-10), magnetic composite materials were prepared by loading Fe3O4 nanoparticles onto thermally reduced graphene oxide and inducing their directional alignment in cement paste using a magnetic field. The results showed that the compressive strength of the cross-section parallel to the magnetic field direction was significantly higher than that perpendicular to it, verifying the role of orientation in regulating the directionality of mechanical properties. However, the composite material prepared by this method had poor electrical conductivity, limiting its potential in applications requiring electrothermal or multifunctional integration.

[0005] Therefore, it is essential to propose a cement-based composite material that combines good electrothermal properties with mechanical and functional properties and exhibits anisotropy. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a cement-based composite material and its preparation method.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A cement-based composite material, by weight parts, comprises 400-500 parts cement, 150-200 parts water, 0.5-1.0 parts water-reducing agent, and 0.12-1.2 parts magnetic graphene.

[0009] Preferably, the cement is PO 42.5 cement.

[0010] Preferably, the water-reducing agent is a polycarboxylate water-reducing agent.

[0011] This invention also provides a method for preparing a cement-based composite material, comprising the following steps:

[0012] S1. Prepare each component according to the specified quantities;

[0013] S2. Mix water, water-reducing agent and magnetic graphene evenly, and then ultrasonically disperse for 10-30 minutes to form a magnetic graphene dispersion;

[0014] S3. The magnetic graphene dispersion obtained in S2 is mixed with cement and stirred evenly, then placed in a standard mold. The standard mold is then placed in a uniform magnetic field generator for orientation treatment to obtain a cement-based composite material.

[0015] Preferably, in step S2, the preparation of the magnetic graphene includes the following steps:

[0016] S21. At room temperature, the graphene oxide solution and ferric ammonium citrate are mixed and stirred until homogeneous to obtain a mixed solution;

[0017] S22. The mixed solution obtained in S21 was subjected to ultrasonic dispersion, freeze-drying, calcination, and then cooled to room temperature to obtain a black powder sample;

[0018] S23. The black powder sample obtained in S22 is washed with deionized water until the pH of the suspension is neutral, and then dried to obtain magnetic graphene.

[0019] Preferably, the concentration of graphene oxide is 5-8 mg / ml, and the mass ratio of graphene oxide to ferric ammonium citrate is 3:1-6:1.

[0020] Preferably, in step S22, the ultrasonic dispersion treatment time is 10~30 min, the freeze drying time is 24~48 h, the calcination is carried out under a nitrogen atmosphere, the calcination heating rate is 5~10℃ / min, the calcination temperature is 600~1000℃, and the calcination time is 1~3 h.

[0021] Preferably, in step S23, the drying temperature is 80~120℃ and the drying time is 4~12h.

[0022] Preferably, in step S3, the stirring speed is 300~1800 r / min and the stirring time is 4~10 min.

[0023] Preferably, in step S3, the magnetic field strength generated by the uniform magnetic field generator is 0~0.1T, and the action time is 0~20min.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention successfully constructs cement-based composite materials with significant anisotropic properties by inducing the directional alignment of magnetic graphene in a cement-based composite material using a magnetic field. This strategy cleverly utilizes the inherent two-dimensional anisotropic structure of graphene, enabling its ordered distribution in a specific direction. This significantly improves the mechanical, electrical, and thermal properties of the cement-based composite material in directions perpendicular or parallel to the magnetic field without excessively increasing the filler content. This method not only effectively solves the core problem of poor applicability of traditional cement-based materials in special multifunctional applications through directional reinforcement, but also maximizes the reinforcement efficiency by optimizing the spatial orientation of the nanofiller, becoming a more economical and efficient performance improvement strategy. It provides an innovative approach that combines high performance and cost-effectiveness for expanding the advanced applications of cement-based composite materials.

[0026] 2. This invention successfully synthesizes a structurally and structurally superior magnetic graphene composite material through a simple and controllable in-situ preparation process. The core of this process lies in firstly achieving molecular-level homogeneous mixing of the oxygen-containing functional groups on the surface of graphene oxide with iron ions in ferric ammonium citrate through coordination or electrostatic interactions; subsequently, heat treatment under nitrogen protection allows the citrate ions to simultaneously act as a carbon source and reducing agent, decomposing in situ to generate magnetic nanoparticles primarily composed of Fe3O4 and containing highly conductive zero-valent iron (elemental iron), while simultaneously achieving the thermal reduction of graphene oxide, partially restoring its sp(s) content. 2 A carbon network is used to enhance conductivity. During this process, newly generated magnetic nanoparticles are in situ and firmly "anchored" to the surface or interlayer of the reducing graphene sheets. The graphene carrier effectively restricts particle migration and aggregation, thus ensuring the small size and high dispersion of the magnetic particles. The resulting composite material perfectly combines the high specific surface area and excellent electrical / thermal conductivity of reduced graphene oxide with uniformly dispersed magnetic nanoparticles (especially Fe). 0 The strong magnetism and additional conductivity provided by the magnetic source and the conductive carrier enable efficient synergy at the nanoscale, laying a key material foundation for subsequently endowing cement matrices with multifunctional and anisotropic properties. Attached Figure Description

[0027] Figure 1This is the X-ray diffraction (XRD) pattern of the magnetic graphene of the present invention.

[0028] Figure 2 This is the magnetic graphene vibrating sample magnetometer test and analysis spectrum (VSM) of the present invention.

[0029] Figure 3 This is a schematic diagram of the directional distribution of magnetic graphene induced by magnetic field in cement-based composite materials in this invention. Detailed Implementation

[0030] The present invention will be further described in detail below through specific embodiments:

[0031] Example 1

[0032] S1. At room temperature, graphene oxide with a concentration of 5 mg / ml and ferric ammonium citrate are mixed and stirred until homogeneous to obtain a mixed solution, wherein the mass ratio of graphene oxide to ferric ammonium citrate is 3:1;

[0033] S2. After ultrasonic dispersion of the mixed solution obtained in S1 for 10 min, it was freeze-dried in a freeze dryer for 24 h, and then placed in a high-temperature tube furnace under nitrogen atmosphere and heated to 600 °C for 3 h at a heating rate of 5 °C / min. After cooling to room temperature, a black powder sample was obtained.

[0034] S3. The black powder sample obtained in S2 was washed with deionized water until the pH of the suspension was neutral, and then dried at 80°C for 12 hours to obtain magnetic graphene.

[0035] S4. Mix 175g of water, 0.75g of polycarboxylate superplasticizer and 0.12g of magnetic graphene prepared in S3, and then ultrasonically disperse for 20min to form a magnetic graphene dispersion.

[0036] S5. Mix 425g of cement and the magnetic graphene dispersion obtained in S4 and stir at 300r / min for 10min. Then place it in a standard mold and put the standard mold into a uniform magnetic field generator for orientation treatment. The uniform magnetic field generator generates a magnetic field strength of 0.075T and takes 6min.

[0037] Example 2

[0038] S1. At room temperature, graphene oxide with a concentration of 8 mg / ml and ferric ammonium citrate are mixed and stirred until homogeneous to obtain a mixed solution, wherein the mass ratio of graphene oxide to ferric ammonium citrate is 6:1;

[0039] S2. After ultrasonic dispersion of the mixed solution obtained in S1 for 30 min, it was freeze-dried in a freeze dryer for 36 h, and then placed in a high-temperature tube furnace under nitrogen atmosphere and heated to 1000 °C for 1 h at a heating rate of 10 °C / min. After cooling to room temperature, a black powder sample was obtained.

[0040] S3. The black powder sample obtained in S2 was washed with deionized water until the pH of the suspension was neutral, and then dried at 120℃ for 4 hours to obtain magnetic graphene.

[0041] S4. Mix 200g of water, 1.0g of polycarboxylate superplasticizer and 1.0g of magnetic graphene prepared in S3, and then ultrasonically disperse for 30min to form a magnetic graphene dispersion.

[0042] S5. Mix 500g of cement and the magnetic graphene dispersion obtained in S4 and stir at 1800r / min for 4min. Then place it in a standard mold and put the standard mold into a uniform magnetic field generator for orientation treatment. The uniform magnetic field generator generates a magnetic field strength of 0.05T for 2min.

[0043] Example 3

[0044] S1. At room temperature, graphene oxide with a concentration of 6 mg / ml was mixed and stirred until homogeneous to obtain a mixed solution, wherein the mass ratio of graphene oxide to ferric ammonium citrate was 5:1.

[0045] S2. After ultrasonic dispersion of the mixed solution obtained in S1 for 20 min, it was freeze-dried in a freeze dryer for 48 h, and then placed in a high-temperature tube furnace under nitrogen atmosphere and heated to 800 °C for 2 h at a heating rate of 7 °C / min. After cooling to room temperature, a black powder sample was obtained.

[0046] S3. The black powder sample obtained in S2 was washed with deionized water until the pH of the suspension was neutral, and then dried at 100℃ for 8 hours to obtain magnetic graphene.

[0047] S4. Mix 150g of water, 0.5g of polycarboxylate superplasticizer and 0.75g of magnetic graphene prepared in S3, and then ultrasonically disperse for 10min to form a magnetic graphene dispersion.

[0048] S5. Mix 400g of cement with the magnetic graphene dispersion obtained in S4 and stir at 1000r / min for 7min. Then place it in a standard mold and put the standard mold into a uniform magnetic field generator for orientation treatment. The uniform magnetic field generator generates a magnetic field strength of 0.01T and the time taken is 20min.

[0049] Example 4

[0050] Compared with Example 1, the difference is that the amount of magnetic graphene added is 0.48g, and all other aspects are the same.

[0051] Example 5

[0052] Compared with Example 1, the difference is that the amount of magnetic graphene added is 1.2g, and all other aspects are the same.

[0053] Example 6

[0054] Compared with Example 1, the difference is that the magnetic field strength generated by the uniform magnetic field generator is 0.1T, while the rest are the same.

[0055] Example 7

[0056] Compared with Example 1, the difference is that the uniform magnetic field generator operates for 10 minutes, while the rest are the same.

[0057] The directional distribution of magnetic graphene in cement-based composite materials induced by a uniform magnetic field generator in Examples 1-7 above is illustrated as follows: Figure 3 As shown.

[0058] Blank groups without the addition of magnetic graphene were prepared for Examples 1 and 4-7 above.

[0059] The cement-based composite materials of Examples 1, 4-7 and corresponding blank groups after directional treatment were cured for 28 days according to the standard of "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-2021). Then, the compressive strength, electrothermal performance and resistivity were tested and the data were compared. The surface of the cement-based composite material parallel to the magnetic field direction was denoted as FA surface and the surface perpendicular to the magnetic field direction was denoted as FB surface. The specific data comparison results are shown in the table below.

[0060]

[0061] In the table above, "+" indicates an increase, "-" indicates a decrease, and " / " indicates no comparison was made.

[0062] As can be seen from the table above, the FA and FB surfaces of the cement-based composite material exhibit anisotropic properties. Specifically, comparing Example 1 with Examples 4-5 shows that, under the same magnetic field strength and treatment time, appropriately increasing the amount of magnetic graphene can significantly improve the performance of the cement-based composite material. Comparing Example 1 with Example 6 shows that, under the same amount of magnetic graphene and treatment time, appropriately increasing the magnetic field strength can significantly improve the performance of the cement-based composite material. Comparing Example 1 with Example 7 shows that, under the same amount of magnetic graphene and magnetic field strength, appropriately increasing the treatment time can significantly improve the performance of the cement-based composite material.

[0063] And as Figure 1 As shown, the X-ray diffraction (XRD) pattern of the magnetic graphene (MGO) prepared in this invention reveals three main components: graphene, Fe3O4, and elemental iron (Fe). Multiple clear diffraction peaks appear in the spectrum within the range of 20° to 60°. The peak for graphene appears around 22°, the characteristic diffraction peaks for Fe3O4 are clearly visible at 30°, 35°, 43°, and 53°, while the diffraction peak for elemental iron appears at 62°. The appearance of these characteristic peaks indicates that the presence of graphene, Fe3O4, and Fe during the synthesis of magnetic graphene is related to the structure of the resulting composite material, demonstrating that the material possesses excellent magnetic properties. This result provides a theoretical basis for subsequent characterization of its magnetic properties.

[0064] In addition, such as Figure 2 As shown, the hysteresis loop (VSM test) of magnetic graphene (MGO) indicates that it possesses significant magnetism compared to the graphene oxide (GO) sample. The magnetization of magnetic graphene (MGO) exhibits a rapid response to changes in the applied magnetic field, and the change in magnetization is relatively smooth. The saturation magnetization (MS) of magnetic graphene is approximately 14 emu / g, indicating its strong magnetism and rapid response even under weak magnetic fields.

[0065] Finally, it should be noted that 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 technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A cementitious composite material, characterized by, By weight, it includes 400-500 parts cement, 150-200 parts water, 0.5-1.0 parts water-reducing agent, and 0.12-1.2 parts magnetic graphene.

2. A cementitious composite material according to claim 1, wherein, The cement is PO 42.5 cement.

3. A cementitious composite material according to claim 1, wherein The water-reducing agent is a polycarboxylate water-reducing agent.

4. The method for preparing a cement-based composite material according to claim 1, characterized in that, Includes the following steps: S1. Prepare each component according to the specified quantities; S2. Mix water, water-reducing agent and magnetic graphene evenly, and then ultrasonically disperse for 10-30 minutes to form a magnetic graphene dispersion; S3. The magnetic graphene dispersion obtained in S2 is mixed with cement and stirred evenly, then placed in a standard mold. The standard mold is then placed in a uniform magnetic field generator for orientation treatment to obtain a cement-based composite material.

5. The method for preparing a cement-based composite material according to claim 4, characterized in that, In step S2, the preparation of the magnetic graphene includes the following steps: S21. At room temperature, the graphene oxide solution and ferric ammonium citrate are mixed and stirred until homogeneous to obtain a mixed solution; S22. The mixed solution obtained in S21 was subjected to ultrasonic dispersion, freeze-drying, calcination, and then cooled to room temperature to obtain a black powder sample; S23. The black powder sample obtained in S22 is washed with deionized water until the pH of the suspension is neutral, and then dried to obtain magnetic graphene.

6. The method for preparing a cement-based composite material according to claim 5, characterized in that, The concentration of graphene oxide is 5~8 mg / ml, and the mass ratio of graphene oxide to ferric ammonium citrate is 3:1~6:

1.

7. The method for preparing a cement-based composite material according to claim 5, characterized in that, In step S22, the ultrasonic dispersion treatment time is 10~30 min, the freeze drying time is 24~48 h, the calcination is carried out under a nitrogen atmosphere, the calcination heating rate is 5~10℃ / min, the calcination temperature is 600~1000℃, and the calcination time is 1~3 h.

8. The method for preparing a cement-based composite material according to claim 5, characterized in that, In step S23, the drying temperature is 80~120℃ and the drying time is 4~12h.

9. The method for preparing a cement-based composite material according to claim 4, characterized in that, In step S3, the stirring speed is 300~1800 r / min and the stirring time is 4~10 min.

10. The method for preparing a cement-based composite material according to claim 4, characterized in that, In step S3, the magnetic field strength generated by the uniform magnetic field generator is 0~0.1T, and the action time is 0~20min.

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