Fiber-reinforced negative carbon type composite material and preparation method thereof

Abstract

The invention discloses a fiber reinforced negative carbon type composite material, which is prepared from the following ingredients in parts by weight: 50 to 130 parts of vaterite type calcium carbonate, 0.2 to 2.5 parts of magnesium salt, 1.0 to 4.5 parts of strontium salt, 10 to 70 parts of water, 0.03 to 4 parts of polyvinyl alcohol and 0.1 to 5 parts of superfine fibers. The preparation method comprises the following steps: dissolving magnesium salt and strontium salt in water, then adding polyvinyl alcohol, and stirring and dissolving at 30-95 DEG C to obtain a homogeneous mixed solution; adding vaterite type calcium carbonate into the mixed solution, stirring for 1-3 minutes until a slurry state appears, then adding superfine fibers, and continuously stirring for 3-5 minutes to obtain slurry in which the fibers are uniformly dispersed; and pouring the slurry into a mold for molding, carrying out steam curing at 50-90 DEG C for 1-8 hours, demolding, and drying at 90-130 DEG C for 8-20 hours to obtain the fiber-reinforced negative carbon type composite material. The polyvinyl alcohol is added in the forming and stirring process to adjust the viscosity of the system, so that high dispersion of fibers is realized, the environmental protection characteristic of the negative carbon type composite material is maintained, the mechanical property of the negative carbon type composite material is remarkably improved, and the application range of the negative carbon type composite material in the fields of buildings and engineering is widened.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and specifically relates to a fiber-reinforced negative carbon composite material and a preparation method thereof. Background Art

[0002] Globally, climate change and sustainable development have become the focus of attention of governments and the international community. With the acceleration of industrialization, the carbon emissions generated in the production and use of various materials have continued to increase, which has had a significant impact on the global climate. In order to meet this challenge, all walks of life are actively seeking effective ways to reduce carbon emissions and improve resource utilization efficiency.

[0003] As an innovative solution, carbon-negative cementitious materials have attracted much attention for their unique carbon reduction properties. This type of material can not only absorb and fix carbon dioxide during the production process, thereby reducing the greenhouse gas content in the atmosphere, but also continue to exert its environmental benefits during use. The research and development and application of carbon-negative cementitious materials have not only brought revolutionary changes to the building materials industry, but also provided new possibilities for achieving global carbon reduction goals.

[0004] In the process of exploring the performance optimization of negative carbon cementitious materials, the enhancement of their mechanical strength is particularly critical. Although this type of material has obvious advantages in reducing environmental impact, its lack of mechanical properties restricts its promotion in a wider range of application scenarios. The strength of this material mainly comes from the mechanical interlocking force generated by the overlapping of aragonite crystals. However, due to the limited strength of the crystals themselves, when subjected to external forces, the crystals are prone to break, resulting in a brittle fracture pattern for the entire material. In addition, since aragonite crystals are transformed from vaterite, they generally radiate from the center of the sphere to form spherical aragonite clusters, which leads to microscopic system inhomogeneity, and there may be stress concentration in the system, resulting in insufficient mechanical properties. In order to enhance its mechanical properties, researchers have explored and implemented a variety of strategies, such as improving the generation environment of aragonite crystals and introducing a variety of blending materials. However, these attempts usually only achieve limited performance improvements and may generate other environmental challenges.

[0005] Fiber-reinforced materials are considered to be an ideal reinforcement material due to their excellent mechanical properties and lightweight characteristics. In particular, ultrafine fibers, due to their extremely high tensile strength and elastic modulus, can significantly improve the mechanical properties of materials at a very small volume fraction. However, due to the high specific surface area and easy agglomeration of ultrafine fibers, it is difficult to achieve uniform dispersion in the material matrix, which not only reduces the reinforcement effect of the fibers, but may also cause local weakening of material properties due to stress concentration in the agglomerates, and even cause harm.

[0006] How to evenly disperse ultrafine fibers in negative carbon gelling materials has become a technical problem that needs to be solved urgently. Summary of the invention

[0007] The purpose of the present invention is to provide a fiber-reinforced negative carbon composite material and a preparation method thereof. By adding polyvinyl alcohol to adjust the viscosity of the system during the molding and stirring process, the high dispersion of the fibers is achieved. While maintaining the environmental protection characteristics of the negative carbon composite material, its mechanical properties are significantly improved, thereby broadening its application range in the fields of construction and engineering.

[0008] In order to achieve the above purpose, the technical solution is as follows:

[0009] A fiber-reinforced negative carbon composite material, the composition of which is as follows by weight:

[0010] 50-130 parts of vaterite calcium carbonate, 0.2-2.5 parts of magnesium salt, 1.0-4.5 parts of strontium salt, 10-70 parts of water, 0.03-4 parts of polyvinyl alcohol, and 0.1-5 parts of ultrafine fibers.

[0011] According to the above scheme, the magnesium salt is one or a mixture of MgCl2 and Mg(NO3)2.

[0012] According to the above scheme, the strontium salt is one or a mixture of SrCl2 and Sr(NO3)2.

[0013] According to the above scheme, the polyvinyl alcohol is one or more of polyvinyl alcohol type 1788, polyvinyl alcohol type 1799, and polyvinyl alcohol type 124.

[0014] According to the above scheme, the ultrafine fiber is one of carbon fiber, ultra-high molecular weight polyethylene fiber and stainless steel fiber; the fiber diameter is 1-200 μm and the length is 1-10 mm.

[0015] According to the above scheme, the vaterite type calcium carbonate is prepared in the following manner:

[0016] Utilize NH4 + The solution dissolves the soluble calcium in the industrial by-products, and after filtration, a calcium ion-rich solution is obtained;

[0017] The CO2-containing tail gas is passed into a calcium ion-rich solution by a bubbling method to obtain a suspension containing calcium carbonate precipitate;

[0018] The vaterite-type calcium carbonate was obtained by suction filtration and drying.

[0019] According to the above scheme, the NH4 + The solution is one of NH4Cl, NH4NO3, CH3COONH4 or any mixture thereof, wherein NH4 + The concentration is 0.2~3.8mol / L.

[0020] According to the above scheme, the industrial by-product is carbide slag, wherein the CaO content is ≥60wt%.

[0021] According to the above scheme, the NH4 + The mass ratio of the solution to the industrial by-product is 5-40.

[0022] According to the above scheme, the CO2-containing tail gas is industrial flue gas, in which the CO2 concentration is 10vt% to 37vt%.

[0023] The method for preparing the fiber-reinforced negative carbon composite material comprises the following steps:

[0024] (1) dissolving magnesium salt and strontium salt in water, then adding polyvinyl alcohol and stirring to dissolve at 30-95° C. to obtain a homogeneous mixed solution;

[0025] (2) adding aragonite calcium carbonate to the mixed solution, stirring for 1 to 3 minutes until a slurry state is formed, then adding ultrafine fibers, and continuing to stir for 3 to 5 minutes to obtain a slurry in which the fibers are evenly dispersed;

[0026] (3) The slurry is poured into a mold to form the slurry, and then the slurry is heated and cured to obtain a fiber-reinforced carbon-negative composite material.

[0027] According to the above scheme, the curing process includes: steam curing at 50-90°C for 1-8 hours, demoulding, and drying at 90-130°C for 8-20 hours.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The addition of polyvinyl alcohol optimizes the dispersion of ultrafine fibers in negative carbon gelling materials. The addition of polyvinyl alcohol changes the viscosity of the slurry, providing an environment for the uniform dispersion of ultrafine fibers, thereby avoiding the agglomeration of fibers and ensuring that the fibers are evenly distributed throughout the material system.

[0030] The addition of ultrafine fibers, combined with the viscosity regulating effect of polyvinyl alcohol solution, has significantly improved the mechanical properties of the material. The high strength and high modulus characteristics of ultrafine fibers, combined with the enhanced cohesion of polyvinyl alcohol solution, work together on the material to improve its compression, tension and durability.

[0031] As a widely used and cost-effective polymer, polyvinyl alcohol is used in the present invention to further reduce the overall material cost. The present invention achieves cost-effectiveness optimization through the composite effect of polyvinyl alcohol and ultrafine fibers without sacrificing environmental friendliness.

[0032] The present invention effectively disperses the ultrafine fibers evenly in the negative carbon type cementitious material through the interaction between the ultrafine fibers and the polyvinyl alcohol solution, which not only forms a multi-phase and multi-scale fiber toughening system to reduce internal stress concentration, but also gives full play to the reinforcing effect of the fibers themselves, thereby significantly improving the compressive strength, tensile strength and durability of the material, thereby promoting the widespread application of this type of environmentally friendly material in the construction industry.

[0033] By adding magnesium salts to the system, the transformation of vaterite to aragonite is directionally regulated, and the needle-rod-shaped aragonite crystals formed overlap each other to gain strength for the system. In addition, since strontium carbonate and aragonitic calcium carbonate have highly consistent crystal structures, strontium atoms can occupy some of the calcium atom sites in aragonite to form a solid solution during the crystal transformation process, giving the system higher strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : Photos of the stirred slurries of Examples 1-3.

[0035] Figure 2 : Surface morphology of Examples 1-3 after hardening. DETAILED DESCRIPTION

[0036] The following examples further illustrate the technical solution of the present invention, but are not intended to limit the scope of protection of the present invention.

[0037] The specific implementation method provides a vaterite type calcium carbonate: carbide slag is selected as an industrial by-product, and its CaO content is 70.18%. A 2 mol / L NH4Cl solution is prepared, and calcium ions are extracted at a liquid-to-solid ratio of 20. The calcium ion-rich solution obtained after suction filtration is carbonized by a bubbling method, wherein the CO2 concentration is 20%, and the reaction is stopped after the solution pH is 7, and the suspension is suction filtered, and the filter residue is dried to obtain the vaterite type calcium carbonate.

[0038] The specific embodiment also provides a method for preparing a fiber-reinforced negative carbon composite material:

[0039] Dissolving magnesium salt and strontium salt in water to prepare a mixed solution containing magnesium ions and strontium ions, then adding polyvinyl alcohol to the mixed solution containing magnesium ions and strontium ions, stirring and dissolving at 90° C. to obtain a homogeneous mixed solution;

[0040] Add aragonite calcium carbonate into a stirring pot and stir, then add the above homogenized mixed solution and stir for 1-3 minutes until a slurry state appears, then add ultrafine fibers and continue stirring for 5 minutes to obtain a slurry with uniform fiber dispersion;

[0041] The slurry was poured into a mold, vibrated to defoam, and a 40×40×160 mm test block was formed. After forming, the test block was placed at 90°C for steam curing for 4 hours and then demolded. The test block was placed in an oven at 105°C for drying for 8 hours before the strength test was carried out.

[0042] A total of 9 groups of different ratios were designed, numbered 1-1, 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, and 1-9. The content of each component is given in mass fraction in Table 1. Among them, polyvinyl alcohol is polyvinyl alcohol-1799 type, the carbon fiber size is Φ2μm×2mm, the micro stainless steel fiber size is Φ5μm×5mm, and the ultra-high molecular weight polyethylene fiber (UHMWPE) size is Φ150μm×10mm.

[0043] Table 1

[0044] serial number Vaterite calcium carbonate <![CDATA[MgCl2]]> <![CDATA[SrCl2]]> water Polyvinyl alcohol Microfiber 1-1 96 0.8 2.8 41.4 0.82 0.1 Carbon fiber 1-2 96 0.8 2.8 41.4 0.97 0.15 Carbon Fiber 1-3 96 0.8 2.8 41.4 1.13 0.2 Carbon fiber 1-4 96 0.8 2.8 41.4 0.67 0.68 micro stainless steel fiber 1-5 96 0.8 2.8 41.4 0.90 1.02 Micro stainless steel fiber 1-6 96 0.8 2.8 41.4 0.97 1.29 Micro stainless steel fiber 1-7 96 0.8 2.8 41.4 0.97 0.25UHMWPE 1-8 96 0.8 2.8 41.4 0.97 0.67UHMWPE 1-9 96 0.8 2.8 41.4 0.97 1.32UHMWPE

[0045] Comparative Example 1

[0046] Compared with Examples 1-3, in Comparative Example 1, polyvinyl alcohol and ultrafine fibers are not added, and other components and steps remain the same.

[0047] Comparative Example 2

[0048] Compared with Examples 1-3, in Comparative Example 2, only polyvinyl alcohol is added, but microfibers are not added, and other components and steps remain the same.

[0049] Comparative Example 3

[0050] Compared with Examples 1-3, in Comparative Example 3, polyvinyl alcohol was not added, but the same mass of carbon fiber was added, and other components and steps remained the same.

[0051] The compressive and flexural strengths of the embodiments and comparative examples are shown in Table 2.

[0052] Table 2

[0053]

[0054]

[0055] It can be seen from Table 2 that the compressive strength of almost all groups exceeds that of Comparative Example 1, which means that the ultrafine fibers and polyvinyl alcohol have a synergistic effect on compressive strength. It is worth noting that the compressive strength of Comparative Example 3 is slightly lower than that of Comparative Example 1. This is because polyvinyl alcohol is not added to the system, and the slurry viscosity does not reach a threshold for suitable fiber dispersion, which may cause carbon fibers to agglomerate in the system and introduce excessive defects. For Examples 1-1, 1-2, and 1-3, the strength basically increases with the increase in the amount of carbon fiber added, which means that the current amount does not reach the carbon fiber capacity threshold of the system, and the compressive strength and flexural strength are increased by 50% and 78% respectively relative to Comparative Example 1.

[0056] Figure 1 and Figure 2 The slurry images during stirring and the surface morphology images after hardening of Examples 1-3 are shown respectively. It is obvious that the carbon fibers in the system are basically evenly distributed and no agglomeration occurs. After adding micro stainless steel fibers, the compressive strength and flexural strength are increased by 40% and 180% respectively relative to Comparative Example 1, but the strength of Examples 1-6 is reduced relative to that of Examples 1-5, which may be due to the excessive amount of micro stainless steel fibers, resulting in defects caused by intertwining and interlacing between fibers.

[0057] The above embodiments are only examples for explanation and are not any limitation to the implementation methods. For those skilled in the art, any equivalent modification and substitution of the present invention is also within the protection scope of the claims of the present invention.

Claims

1. A fiber-reinforced negative carbon composite material, characterized in that The composition is calculated by weight as follows: 50-130 parts of vaterite calcium carbonate, 0.2-2.5 parts of magnesium salt, 1.0-4.5 parts of strontium salt, 10-70 parts of water, 0.03-4 parts of polyvinyl alcohol, and 0.1-5 parts of ultrafine fibers.

2. The fiber-reinforced negative carbon composite material according to claim 1, characterized in that The magnesium salt is one or a mixture of MgCl2 and Mg(NO3)2.

3. The fiber-reinforced negative carbon composite material according to claim 1, characterized in that The strontium salt is one or a mixture of SrCl2 and Sr(NO3)2.

4. The fiber-reinforced negative carbon composite material according to claim 1, characterized in that The polyvinyl alcohol is one or more of polyvinyl alcohol 1788 type, polyvinyl alcohol 1799 type, and polyvinyl alcohol 124 type.

5. The fiber-reinforced negative carbon composite material according to claim 1, characterized in that The ultrafine fiber is one of carbon fiber, ultra-high molecular weight polyethylene fiber and stainless steel fiber; the fiber diameter is 1-200 μm and the length is 1-10 mm.

6. The fiber-reinforced negative carbon composite material according to claim 1, characterized in that Described vaterite type calcium carbonate is prepared in the following manner: Utilize NH4 + The solution dissolves the soluble calcium in the industrial by-products, and after filtration, a calcium ion-rich solution is obtained; The CO2-containing tail gas is passed into a calcium ion-rich solution by a bubbling method to obtain a suspension containing calcium carbonate precipitate; The vaterite-type calcium carbonate was obtained by suction filtration and drying.

7. The fiber-reinforced negative carbon composite material according to claim 6, characterized in that The NH4 + The solution is one of NH4Cl, NH4NO3, CH3COONH4 or any mixture thereof, wherein NH4 + The concentration is 0.2~3.8mol / L.

8. The fiber-reinforced negative carbon composite material according to claim 6, characterized in that The industrial by-product is carbide slag, wherein the CaO content is ≥ 60wt%.

9. The fiber-reinforced negative carbon composite material according to claim 6, characterized in that The NH4 + The mass ratio of the solution to the industrial by-product is 5-40.

10. The method for preparing the fiber-reinforced negative carbon composite material according to claim 1, characterized in that The following steps are involved: (1) dissolving magnesium salt and strontium salt in water, then adding polyvinyl alcohol and stirring to dissolve at 30-95° C. to obtain a homogeneous mixed solution; (2) adding aragonite calcium carbonate to the mixed solution, stirring for 1 to 3 minutes until a slurry state is formed, then adding ultrafine fibers, and continuing to stir for 3 to 5 minutes to obtain a slurry in which the fibers are evenly dispersed; (3) The slurry is poured into a mold for forming, steam cured at 50 to 90° C. for 1 to 8 h, then demolded, and dried at 90 to 130° C. for 8 to 20 h to obtain a fiber-reinforced negative carbon composite material.

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