SCA modified basalt fiber cement base and preparation method thereof

Abstract

The invention belongs to the field of fiber reinforced composite materials, and provides an SCA modified basalt fiber cement base and a preparation method thereof.The preparation method comprises the following steps that basalt fibers are pretreated; a gamma-aminopropyltriethoxysilane solution, a gamma-glycidyl ether oxypropyltrimethoxysilane solution and a gamma-methacryloyloxypropyltrimethoxysilane solution are prepared, and the dried basalt fibers are soaked in the solutions respectively to be modified; naturally airing at room temperature after soaking, drying in an air dry oven, cooling to room temperature, and sealing and storing; carrying out dry mixing on the modified basalt fiber, ordinary Portland cement, sand and an additive to prepare an SCA modified basalt fiber cement base; by adopting different SCAs and introducing additional reaction functional groups, the interface bonding strength between the basalt fibers and a cement matrix is improved, and the problem of non-uniform fiber dispersion is solved, so that the comprehensive performance of the material is improved.

Description

Technical Field

[0001] The invention belongs to the field of fiber-reinforced composite materials, in particular to an SCA-modified basalt fiber cement-based composite and a preparation method thereof. Background Art

[0002] Basalt fiber-reinforced cementitious composites (BFRCC) are an emerging natural green and environmentally friendly composite material. Compared with traditional cement materials, they have shown significant advantages in improving the strength, toughness and crack resistance of building structures. However, the surface of basalt fiber (BF) is smooth and has poor adhesion to the cement matrix, which can easily cause a certain degree of interface weakening. At the same time, the fiber surface has few functional groups, showing chemical inertness, and it is difficult to form effective chemical bonds with the cement matrix. It may become a potential weak area in the structure, which leads to the inability to fully exert the toughening effect of basalt fiber. Therefore, some scholars have improved the interface properties between BF and the cement matrix by treating the surface, such as acid-base etching, plasma modification, silane coupling agent modification and nanoparticle modification;

[0003] However, the interfacial bonding strength between basalt fiber and the cement matrix is ​​often insufficient, resulting in debonding between the fiber and the matrix under stress. This limits the contribution of the fiber to the reinforced material to a certain extent. In addition, in the existing technology, the fiber modification methods are mostly concentrated in a single direction of physical modification or chemical modification, and the types of modifiers used are relatively few, resulting in insufficient flexibility. This limits further improvement in material performance. Although some modification technologies have improved the strength and toughness of the material in the short term, they lack long-term durability test data, making it difficult to predict the performance of these materials in long-term use. At the same time, during the production process, conventional batching methods may cause uneven dispersion of basalt fiber in the cement matrix. Fiber aggregation or uneven distribution may lead to a decrease in local strength, thereby affecting the mechanical properties of the overall material.

[0004] To this end, those skilled in the art have proposed an SCA-modified basalt fiber cement-based composite and a preparation method thereof. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an SCA modified basalt fiber cement-based material and a preparation method thereof to solve the problems raised by the background technology.

[0006] According to a first aspect of the present disclosure, a method for preparing an SCA-modified basalt fiber cement-based composite is proposed, comprising the following steps:

[0007] S1. Pre-treating the basalt fiber by soaking it in an acetone solution, vibrating it with an ultrasonic oscillator, washing it with deionized water, and then drying it in an air drying oven;

[0008] S2, preparing solutions of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane, and immersing the dried basalt fibers in the solutions for modification;

[0009] S3. After soaking, dry naturally at room temperature, place in a blast drying oven for drying, cool to room temperature and seal for storage;

[0010] S4. Dry-mix the modified basalt fiber with ordinary Portland cement, sand, and admixture for 2 minutes to evenly distribute the fibers in the matrix. Then add purified water and mix for 5 minutes, then vibrate and shape. Remove the mold after 24 hours to obtain the SCA modified basalt fiber cement matrix.

[0011] Preferably, in step S1, the ultrasonic oscillator is oscillated at 25°C for 20 minutes, and the drying temperature of the blast drying oven is 120°C.

[0012] Preferably, in step S2, the concentration of the γ-aminopropyltriethoxysilane solution is 1.2 wt %, the concentration of the γ-glycidoxypropyltrimethoxysilane solution is 1.8 wt %, and the concentration of the γ-methacryloxypropyltrimethoxysilane solution is 2.4 wt %.

[0013] Preferably, in step S2, acetic acid is used to adjust the pH value of the solution to 4.

[0014] According to the second aspect of the present disclosure, an SCA-modified basalt fiber cement-based composite is proposed, which is prepared using the first aspect of the present disclosure.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention introduces additional reactive functional groups by modifying BF with silane coupling agents γ-aminopropyltriethoxysilane (AP), γ-glycidoxypropyltrimethoxysilane (GP), and γ-methacryloxypropyltrimethoxysilane (MA), thereby preparing AP / GP / MA-BF. By comparing the maximum values ​​of peak load-deflection of BFRCC under three SCAs and concentration-modified BFs, the order from large to small is GP-1.8>AP-1.2>MA-1.2. Therefore, it can be concluded that when only SCA is used to modify BF, the GP-1.8 group achieves the best toughening effect on BFRCC. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1Figure of flexural strength of BFRCC modified by different SCA concentration of the present application under BF;

[0018] Figure 2 Figure of principle of basalt fiber modified by SCA of the present application;

[0019] Figure 3 Figure of load-deflection curve of BFRCC when modified by BF of the present application, wherein Figure 3 a is the load-deflection curve of basalt fiber reinforced fine concrete modified by AP, Figure 3 b is the load-deflection curve of basalt fiber reinforced fine concrete modified by GP, Figure 3 c is the load-deflection curve of basalt fiber reinforced fine concrete modified by MA; load-deflection curve of basalt fiber reinforced fine concrete modified by AP, GP and MA at the optimal concentration;

[0020] Figure 4 Figure of flexural toughness coefficient of BFRCC modified by AP, GP and MA at the optimal mass fraction under BF of the present application;

[0021] Figure 5 Figure of EDS spectrum analysis of the present application, wherein Figure 5 a is the EDS spectrum of unmodified basalt fiber, Figure 5 b is the EDS spectrum of GP-1.8-BF;

[0022] Figure 6 Figure of micrograph analysis of the present application, wherein Figure 6 a is the micrograph of original BF, Figure 6 b is the micrograph of fiber surface AC-BF after the original BF is cleaned by acetone, Figure 6 c is the micrograph of GP-BF modified by GP. DETAILED DESCRIPTION

[0023] The embodiments of the present application will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0024] Embodiment: The present application provides a preparation method of basalt fiber cement-based modified by SCA, comprising the following steps:

[0025] S1, pretreat basalt fiber, immerse the basalt fiber in acetone solution, use ultrasonic oscillator to shake at 25℃ for 20min during the process, clean by deionized water, and then dry by blowing drying oven with drying temperature of 120℃;

[0026] S2, γ-aminopropyltriethoxysilane (AP), γ-glycidoxypropyltrimethoxysilane (GP), γ-methacryloyloxypropyltrimethoxysilane (MA) solution is prepared, the concentration of γ-aminopropyltriethoxysilane solution is 1.2wt%, the concentration of γ-glycidoxypropyltrimethoxysilane solution is 1.8wt%, and the concentration of γ-methacryloyloxypropyltrimethoxysilane solution is 2.4wt%, and the dried basalt fiber is soaked in the above solution for modification; and acetic acid is used to adjust the pH value of the solution to 4.

[0027] S3, after soaking at room temperature, it is naturally dried and then put into a drying oven for drying treatment, and after cooling to room temperature, it is sealed and stored;

[0028] S4, the modified basalt fiber is dry mixed with ordinary Portland cement, sand and additive for 2min, so that the fiber is uniformly distributed in the matrix, and then pure water is added and mixed for 5min, and then vibrated and formed, and after 24h, the mold is removed, and SCA modified basalt fiber cement base is prepared.

[0029] Test example: the toughness index method (JSCE-SF4) proposed by Japan JCI SFRC committee is used, which takes the deflection deformation of the sample to 1 / 150 times of the span as the standard reference point during bending loading, calculates the area under the load-deflection curve, and represents as:

[0030]

[0031] In the formula: is the bending toughness coefficient; T b Area between load and deflection curve in test; δ tb Special deflection value, equal to span divided by 150mm; l is span; b is width of sample; h is height of sample.

[0032] Flexural strength analysis

[0033] The length of 9mm, 1.2wt% BF modified reinforced basalt fiber reinforced cement composite BFRCC is studied. Figure 1 The effect of AP, GP and MA with solution concentration of 1.2wt%, 1.8wt% and 2.4wt% on the flexural strength of BFRCC. From Figure 1The results show that the flexural strength of the BFRCC reached a maximum when the AP solution concentration was 1.2 wt% and then decreased with increasing solution concentration. Compared with the Raw-BF group (SCA concentration was 0 wt%), the flexural strength of the AP-1.2-BF group increased from 8.25 MPa to 8.9 MPa, a 7.88% increase. When the GP solution was used to modify the BF, the flexural strength of the BFRCC initially increased and then decreased with increasing solution concentration, reaching a maximum of 9.08 MPa at a solution concentration of 1.8 wt%, a 10.06% increase compared to the Raw-BF group. When the MA solution was used to modify the BF, the flexural strength of the BFRCC did not increase significantly, and at a MA solution concentration of 2.4 wt%, the flexural strength of the BFRCC decreased by 11.88% (7.27 MPa) compared to the Raw-BF group.

[0034] Figure 2 The schematic diagram of SCA modified BF is shown in Figure 2. Figure 2 As shown, SCA typically acts as an intermediate, with one end containing a silanol group (Si-OH) that reacts with inorganic materials (such as BF) and the other end containing organic functional groups (such as amino or epoxy) that react with the cement matrix. However, different SCAs exhibit varying effects on BFRCC enhancement. AP contains amino (-NH2) functional groups. When in contact with BF, the amino groups can hydrogen bond to the hydroxyl (-OH) groups on the substrate surface. When sufficient hydrogen bonds are present, these hydrogen bonds can enhance interfacial adhesion, effectively "bridging" the material surface and the cement matrix. However, AP is susceptible to hydrolysis and self-polymerization, which can affect the fiber modification effect. GP, on the other hand, contains epoxy groups and is generally highly reactive. Its methoxyl group (-OCH3) first reacts with moisture on the substrate surface, releasing methanol to form a silanol (-SiOH), which then undergoes a ring-opening reaction with the hydroxyl groups on the substrate surface, forming a stable covalent bond. This bond is much stronger and more stable than hydrogen bonds, increasing the crosslinking density of the material while effectively preventing the propagation of microcracks in the cement matrix. MA contains methacryloyloxy groups. Although it has good organic groups, it has poor compatibility with the inorganic part in the cement matrix, which affects the interface performance between them.

[0035] Load-deflection curve analysis

[0036] Figure 3 The effect of AP, GP, MA (concentrations of 1.2wt%, 1.8wt% and 2.4wt%) modified BF on the load-deflection of BFRCC. Figure 3 (a) It can be seen that when AP modifies BF, the deflection deformation decreases with the increase of solution concentration. In the AP-1.2 group, the BFRCC bending toughness is better, with a peak deflection deformation of 0.28 mm, which is 64.71% and 7.69% higher than that of the Blank group (0.17 mm) and the Raw-BF group (0.26 mm). Figure 3(b) It can be seen that when GP modified BF, the deflection deformation of BFRCC showed a downward trend with the increase of solution concentration, and the peak deflection deformation reached the maximum in the GP-1.8 group, which was 0.28 mm, similar to that of the AP-1.2 group; Figure 3 (c) It can be seen that when MA modified BF, the deflection deformation of BFRCC showed a downward trend with the increase of solution concentration, and the peak deflection in the MA-1.2 group reached a maximum value of 0.27 mm, which was 58.82% and 3.85% higher than that in the Blank group and Raw-BF group; Figure 3 As shown in (d), the peak load-deflection values ​​of BFRCC obtained under the three SCA and concentration-modified BF are compared, and the order from large to small is GP-1.8>AP-1.2>MA-1.2; thus, it can be concluded that when SCA alone modifies BF, the GP-1.8 group achieves the best toughening effect on BFRCC.

[0037] Bending toughness coefficient analysis

[0038] Figure 4 is the bending toughness coefficient of BFRCC under modified BF with the optimal mass fraction of AP, GP and MA. b As a key indicator to measure the deformation capacity of specimens under bending loading, the influence of different modification methods on the bending toughness of BFRCC was directly quantified. Figure 4 It can be seen that in the GP-BF group (modified solution concentration is 1.8wt%) BFRCCσ b It reached a maximum of 0.81 MPa, which was an increase of 102.5% and 19.12% compared with the Blank group (0.4 MPa) and Raw-BF (0.68 MPa), respectively; while the enhancement effect of the AP-BF group (0.78 MPa) and MA-BF group (0.74 MPa) was relatively weak, with increases of 95%, 14.71% and 85%, 8.82% compared with the Blank and Raw-BF groups, respectively.

[0039] EDS element spectrum analysis

[0040] Figure 5EDS spectra of unmodified basalt fiber (BF) and GP-1.8-BF are shown. As shown in Figure 11(a), BF is primarily composed of silicon dioxide (SiO2) and aluminum oxide (Al2O3) (with a relatively low carbon content), with small amounts of metal oxides such as iron (Fe), sodium (Na), and magnesium (Mg). Figure 11(b) shows that the characteristic peaks of oxygen (O) and silicon (Si) in GP-modified BF increase slightly compared to unmodified BF, with the atomic percentage of Si reaching 14.42 at%, a 48.2% increase from the 9.73 at% of the original BF. This is attributed to the reaction of GP with hydroxyl groups (-OH) or other oxygen-containing functional groups on the BF surface, forming silicon-oxygen bonds, thereby enhancing the bonding strength between BF and GP.

[0041] Microscopic image analysis

[0042] Figure 6 The micromorphology of BF and mortar matrix after GP modification and reinforcement. Figure 6 (a) It can be seen that the original BF surface is attached with impregnation agent. In order to remove the stains on the BF surface and improve the bonding performance of BF with other materials, acetone is used for cleaning. The fiber surface after cleaning is as follows: Figure 6 (b) shown. Figure 6 (c) The surface of BF modified by GP is attached to a thin film. Due to the hydrolysis of the siloxane groups in GP, ​​the hydroxyl groups form silicon-oxygen bonds through condensation reaction, thereby forming siloxane chains and forming an adsorption layer on the BF surface.

[0043] in conclusion

[0044] The use of SCA (AP, GP, MA, concentrations of 1.2wt%, 1.8wt%, 2.4wt%) can effectively improve the flexural strength and peak load deflection of the original BFRCC, and the improvement effect is GP-1.8-BF>AP-1.2-BF>MA-1.2-BF from large to small. And by introducing the bending toughness coefficient σ b As an evaluation criterion, the effects of different modified BF methods on the flexural toughness of BFRCC were directly quantified.

[0045] It is important to note that the construction and arrangement of the present application shown in a number of different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, as well as parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, directional changes, etc.) without departing substantially from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structures. Other replacements, modifications, changes, and omissions may be made in the design, operating conditions, and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0046] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (i.e., those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0047] It will be appreciated that in the development of any actual embodiment, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will, for those of ordinary skill having the benefit of this disclosure, be a routine undertaking of design, fabrication, and production without undue experimentation.

[0048] 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 the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing SCA modified basalt fiber cement-based, characterized in that: The following steps are involved: S1. Pre-treating the basalt fiber by soaking it in an acetone solution, vibrating it with an ultrasonic oscillator, washing it with deionized water, and then drying it in an air drying oven; S2, preparing solutions of γ-aminopropyltriethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and γ-methacryloxypropyltrimethoxysilane, and immersing the dried basalt fibers in the solutions for modification; S3. After soaking, dry naturally at room temperature, place in a blast drying oven for drying, cool to room temperature and seal for storage; S4. Dry-mix the modified basalt fiber with ordinary Portland cement, sand, and admixture for 2 minutes to evenly distribute the fibers in the matrix. Then add purified water and mix for 5 minutes, then vibrate and shape. Remove the mold after 24 hours to obtain the SCA modified basalt fiber cement matrix.

2. The method for preparing an SCA-modified basalt fiber cement-based material according to claim 1, wherein: In step S1, the ultrasonic oscillator is oscillated at 25° C. for 20 minutes, and the drying temperature in the blast drying oven is 120° C.

3. The method for preparing an SCA-modified basalt fiber cement-based material according to claim 1, wherein: In step S2, the concentration of the γ-aminopropyltriethoxysilane solution is 1.2 wt %, the concentration of the γ-glycidoxypropyltrimethoxysilane solution is 1.8 wt %, and the concentration of the γ-methacryloxypropyltrimethoxysilane solution is 2.4 wt %.

4. The method for preparing an SCA-modified basalt fiber cement-based material according to claim 1, wherein: In step S2, acetic acid is used to adjust the pH value of the solution to 4.

5. An SCA-modified basalt fiber cement-based material, prepared by the method for preparing an SCA-modified basalt fiber cement-based material according to any one of claims 1 to 4.

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