A high-temperature-resistant super-high-flow nano-modified polymer grouting material, a preparation method and application thereof

Abstract

The application discloses a kind of high-temperature-resistant super-high-flow nano-modified polymer grouting materials and its preparation method and application, belong to geotechnical engineering technical field, the application is with composite Portland cement, fly ash and silica fume as basement, synergic calcium hydroxide, sodium carbonate, cellulose nanofiber, tannic acid controls its hydration process, fluidity and mechanical strength, nano-modified cementation particle is injected into deep surrounding rock, can keep high fluidity in high-temperature environment for a long time, effectively expand grouting diffusion range, and can realize the accurate control of grouting material gelation time.Meanwhile, high mass fraction fly ash and silica fume are excited to produce calcium silicate hydrate, solve the current conventional calcium silicate grouting cementing material in high-temperature environment poor reinforcement impermeability effect, slurry body is easy to crack and other problems.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering technology, and particularly relates to a high-temperature-resistant, ultra-high-flow nano-modified polymer grouting material, its preparation method, and its application. Background Technology

[0002] As shallow mineral resources are depleted, resource development is gradually moving deeper into the earth. For example, coal mining depths have reached 1500m, and metal mining depths have exceeded 4350m. With the continuous increase in the mining depth of both metallic and non-metallic mineral resources, the temperature of the surrounding rock in mine tunnels increases by a gradient of (1-3)℃ / 100m. The high geothermal environment causes conventional grouting materials to fail and greatly reduces the effectiveness of grouting reinforcement and seepage prevention, making it extremely easy to induce major disasters such as collapses, roof falls, water inrushes, and mudslides, seriously threatening the safety and stability of the lifeline engineering of mine tunnels.

[0003] High geothermal environments induce thickening and viscosity of grout, significantly reducing the diffusion range of grouting reinforcement in deep rock masses and affecting the hydration process, posing a severe challenge to the research and development and performance control of grouting materials. To ensure the anti-seepage effect of grouting reinforcement in deep, high-temperature rock masses, it is crucial to control the cementitious properties and fluidity of grouting materials. Currently, commonly used grouting materials include cement and cement-water glass two-component grouts, which tend to solidify rapidly in high-temperature environments, reducing fluidity and making them prone to cracking and rapid strength loss after curing. Especially under high geothermal conditions, the setting time of cement-water glass two-component grouts is too short, easily leading to grout hole blockage. Furthermore, the solidified grout may exhibit an unstable jelly-like or tofu-like consistency, severely weakening the effect and range of deep rock mass grouting reinforcement. To overcome these limitations, specific admixtures are usually added to improve the performance of grouting materials. These admixtures can prolong the setting time, improve the fluidity and stability of the grout, thereby expanding the diffusion effect of the grouting material in high-temperature environments.

[0004] Currently, there are many types of admixtures widely used to regulate the fluidity and gelation time of cementitious materials, such as sodium gluconate, citric acid, tartaric acid, boric acid, and sucrose. To a certain extent, retarded grouting materials have higher fluidity and a wider diffusion range. Their retarding effect mainly depends on the internal functional groups, which are ranked from strongest to weakest as follows: carbon-hydrogen bonds < polyol chains (C... n H 2n+2 - xThe formula (OH) < sulfonic acid group (-SO3H) ≈ carboxyl group (-COOH) < phosphate group (-PO3H2) ≈ hydroxyl group (-OH) < carboxyphosphate shows that the retarding effect of carboxyl groups is not ideal. Therefore, water-reducing agents such as polycarboxylic acid, whose main group is carboxyl group, cannot be widely used in high-temperature grouting materials. Among commonly used retarder, sodium gluconate, citric acid, and tartaric acid also have carboxyl groups as their main group, and their retarding effect is worse than that of hydroxyl-based retarder. Although sucrose has hydroxyl groups, it contains fewer hydroxyl groups, resulting in weaker high-temperature resistance. Boric acid has hydroxyl (-OH) and boron-oxygen bond (BO) as its main groups. The boron atom in the boric acid molecule is bonded to three hydroxyl groups to form a trihydroxyborate group (B(OH)3), thus containing even fewer hydroxyl groups and even worse high-temperature resistance. The above-mentioned admixtures can improve the gelation time and fluidity of grouting materials to a certain extent, but they still cannot meet the extremely high performance requirements of deep high geothermal environments, making them unsuitable for widespread application in deep-earth engineering.

[0005] Therefore, there is an urgent need in this field to develop a high-performance grouting material to solve the problem of diffusion and cementation control in deep, high-temperature surrounding rock grouting. Summary of the Invention

[0006] To address the challenges of diffusion and controlled gelation time in deep, high-temperature surrounding rock grouting, this invention proposes a high-temperature-resistant, ultra-high-flowability nano-modified polymer grouting material, its preparation method, and its applications. This grouting material maintains high fluidity for extended periods under high-temperature conditions, effectively expanding the grouting diffusion range and enabling precise control of the gelation time. Simultaneously, it stimulates the production of calcium aluminosilicate hydration products from high-quality fly ash and silica fume, overcoming the shortcomings of conventional calcium silicate grouting binders, such as poor reinforcement and impermeability under high-temperature conditions and susceptibility to cracking.

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

[0008] One of the technical solutions of the present invention:

[0009] This invention provides a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material, the raw material of which contains both tannic acid and cellulose nanofibers.

[0010] The high-temperature resistant, ultra-high-flow nano-modified polymer grouting material is composed of the following raw materials: cement, fly ash, silica fume, calcium hydroxide, sodium carbonate, tannic acid, cellulose nanofibers, and water.

[0011] Based on the weight percentage of cement, the dosages of other components are as follows:

[0012] The amount of fly ash added should be 70%-80% of the weight of cement.

[0013] The dosage of silica fume is 7%-10% of the cement weight.

[0014] The dosage of tannic acid is 0.2%-0.4% of the cement weight.

[0015] The dosage of cellulose nanofibers is 0.08%-0.25% of the cement weight.

[0016] The dosage of calcium hydroxide is 6%-9% of the cement weight.

[0017] The dosage of sodium carbonate is 3%-5% of the cement weight;

[0018] The water-cement ratio is 0.5.

[0019] Preferably, the amount of tannic acid is 0.2%-0.3% of the cement weight, and the amount of cellulose nanofibers is 0.08%-0.16% of the cement weight.

[0020] More preferably, the amount of tannic acid is 0.3% of the weight of cement, and the amount of cellulose nanofibers is 0.16% of the weight of cement.

[0021] Excessive tannic acid content can lead to excessively long setting time or even failure to set, resulting in low strength in the later stages. Insufficient tannic acid content can prevent the product from achieving its best effect, shortening the setting time and failing to fully disperse the cellulose nanofibers, leading to agglomeration.

[0022] When the content of cellulose nanofibers is too high, the large specific surface area and hydroxyl groups of cellulose nanofibers give them strong water absorption properties, which reduces early flowability and makes it impossible to meet the grouting requirements. When the content is too low, the insufficient content of cellulose nanofibers results in an insignificant bridging effect, which in turn leads to a lower improvement in later strength. This makes it impossible to suppress the development of cracks after injection, and may even cause the cracks to further develop due to their own shrinkage.

[0023] This invention utilizes cement, fly ash, and silica fume, combined with tannic acid and cellulose nanofibers, to prepare a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material. The innovations are: First, tannic acid possesses multiple phenolic hydroxyl groups, which can form intramolecular or intermolecular hydrogen bonds, making it less prone to decomposition at high temperatures and thus exhibiting strong high-temperature stability, allowing it to better adapt to high-temperature environments; second, tannic acid contains numerous pyrogallol groups, which can be adsorbed onto Ca²⁺ ions via covalent or non-covalent methods. 2+ Surface or with Ca 2+The formation of TA-Ca complexes slows down the hydration rate within the cement, thus maintaining high fluidity for a longer period and achieving a retarding effect. Finally, tannic acid itself is amphiphilic, meaning one part of the molecule is hydrophilic (e.g., hydroxyl groups), while the other part is hydrophobic (e.g., benzene rings). This amphiphilic property allows tannic acid to form a stable adsorption layer on the surface of nanoparticles, reducing interparticle interactions and promoting dispersion. The dispersion of cellulose nanofibers reduces agglomeration, resulting in more uniform dispersion. Simultaneously, due to the long aspect ratio of cellulose nanofibers (fiber length much longer than diameter), they can bridge microcracks and pores in the cementitious matrix, forming effective bridging and preventing the cemented particles from breaking down under pressure, thereby improving the sealing effect. Furthermore, the calcium aluminosilicate hydration products generated from high-quality fly ash and silica fume are more stable and less prone to shrinkage and cracking under high geothermal conditions.

[0024] The second technical solution of the present invention:

[0025] This invention also provides a method for preparing the high-temperature resistant, ultra-high-flow nano-modified polymer grouting material, comprising the following steps:

[0026] S1. Accurately weigh each raw material according to the proportion, dry mix cement, fly ash and silica fume to make the three substances evenly mixed, and obtain the composite cementitious base material of the grouting material.

[0027] S2. Divide the water into three equal parts by mass, mix 1 / 3 of the water with tannic acid, stir well to obtain a tannic acid solution;

[0028] S3. Mix 1 / 3 of the water with the cellulose nanofibers and stir until homogeneous to obtain a cellulose nanofiber solution;

[0029] S4. Stir the cellulose nanofiber solution and tannic acid solution evenly, and let them stand after stirring to obtain the first mixed solution. This allows tannic acid to be adsorbed on the surface of cellulose nanofibers, reducing the interaction between particles and thus promoting the further dispersion of cellulose nanofibers.

[0030] S5. Mix 1 / 3 water, sodium carbonate, and calcium hydroxide to obtain a second mixed solution. Sodium carbonate and calcium hydroxide react to produce sodium hydroxide and calcium carbonate. Since the calcium hydroxide content is high, there will be excess calcium hydroxide. The sodium hydroxide and calcium hydroxide produced in the reaction act as alkali activators, enhancing the reactivity of the internal fly ash. Simultaneously, calcium hydroxide can also provide a calcium source, promoting the formation of C(N)-ASH. The generated calcium carbonate can fill the pores inside the cement and can also undergo electrolysis to become calcium ions and carbonate ions, forming calcium aluminate. Since the decomposition temperature of calcium aluminate is higher than that of ettringite, it helps improve the high-temperature resistance of the grouting material.

[0031] S6. Pour the first mixed solution and the second mixed solution into the composite cementitious substrate material and stir evenly to obtain a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material.

[0032] In step S2, the stirring speed is 300 rpm and the stirring time is 2 min.

[0033] In step S3, the stirring rate is 500 rpm and the stirring time is 2 min. High-speed stirring allows the cellulose nanofibers to be initially dispersed, making it easier for tannic acid to be adsorbed on their surface in subsequent processes.

[0034] In step S4, the stirring speed is 300 rpm and the stirring time is 2 min;

[0035] In step S5, the stirring speed is 300 rpm and the stirring time is 2 min.

[0036] In step S6, the stirring speed is 300 rpm and the stirring time is 4 min.

[0037] The third technical solution of the present invention:

[0038] The present invention also provides the application of the high-temperature resistant, ultra-high-flow nano-modified polymer grouting material in grouting of surrounding rock in a high-temperature environment, wherein the high-temperature environment is 40-80℃.

[0039] Compared with the prior art, the present invention has the following advantages and technical effects:

[0040] This invention uses composite silicate cement, fly ash, and silica fume as base materials, and coordinates calcium hydroxide, sodium carbonate, cellulose nanofibers, and tannic acid to regulate their hydration process, fluidity, and mechanical strength. Nano-modified cementitious particles are injected into deep surrounding rock, maintaining high fluidity for extended periods under high geothermal conditions, effectively expanding the grout diffusion range, and enabling precise control of the grouting material's setting time. Simultaneously, it stimulates the production of calcium aluminosilicate hydration products from high-quality fly ash and silica fume, overcoming the shortcomings of conventional calcium silicate grouting cementing materials, such as poor reinforcement and impermeability under high geothermal conditions and easy cracking of the grout. Attached Figure Description

[0041] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0042] Figure 1 Comparative Example 7 shows the silicate hydration and aluminosilicate polymerization process without tannins and cellulose nanofibers.

[0043] Figure 2 This refers to the silicate hydration and aluminosilicate polymerization process when tannic acid and cellulose nanofibers are added in Example 1.

[0044] Figure 3 This is a schematic diagram of the mechanism of tannic acid in mono-cemented particles;

[0045] Figure 4 This is a diagram illustrating the mechanism of tannic acid in multi-cemented particles.

[0046] Figure 5 The images shown are XRD patterns of different curing ages and different admixtures at a curing temperature of 20°C in Example 1.

[0047] Figure 6 The images shown are XRD patterns of different curing ages and different admixtures at a curing temperature of 50°C in Example 2.

[0048] Figure 7 The images shown are XRD patterns of different curing ages and different admixtures at a curing temperature of 80°C in Example 3.

[0049] Figure 8 The cumulative porosity curve of the grouting material slurry in Example 1 is shown when the curing temperature is 20°C.

[0050] Figure 9 The porosity distribution inside the grouting material when the curing temperature is 20℃ in Example 1;

[0051] Figure 10 This is the cumulative porosity curve of the grouting material inside the grout when the curing temperature is 50℃ in Example 2;

[0052] Figure 11 The porosity distribution inside the grouting material at a curing temperature of 50°C in Example 2;

[0053] Figure 12 The cumulative porosity curve inside the grouting material at a curing temperature of 80℃ in Example 3 is shown.

[0054] Figure 13 The porosity distribution inside the grouting material at a curing temperature of 80℃ in Example 3;

[0055] Figure 14 SEM image of the grouting material prepared in Comparative Example 1 after a curing period of 3 days;

[0056] Figure 15 SEM image of the grouting material prepared in Comparative Example 2 after a curing period of 3 days;

[0057] Figure 16 SEM image of the grouting material prepared in Example 1 with a curing period of 3 days;

[0058] Figure 17 SEM image of the grouting material prepared in Comparative Example 3 after a curing period of 3 days;

[0059] Figure 18 SEM image of the grouting material prepared in Comparative Example 4 after a curing period of 3 days;

[0060] Figure 19 SEM image of the grouting material prepared in Example 2 with a curing period of 3 days;

[0061] Figure 20 SEM image of the grouting material prepared in Comparative Example 5 after a curing period of 3 days;

[0062] Figure 21 SEM image of the grouting material prepared in Comparative Example 6 after a curing period of 3 days;

[0063] Figure 22 SEM image of the grouting material prepared in Example 3 with a curing period of 3 days;

[0064] Figure 23 SEM image of ettringite on the surface of aluminum-rich material (fly ash) in Example 3 when the curing period is 3 days. Detailed Implementation

[0065] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0066] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0067] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0068] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0069] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0070] An embodiment of the present invention provides a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material, which is composed of the following raw materials: cement, fly ash, silica fume, calcium hydroxide, sodium carbonate, tannic acid, cellulose nanofibers, and water;

[0071] Based on the weight percentage of cement, the dosages of other components are as follows:

[0072] The amount of fly ash added should be 70%-80% of the weight of cement.

[0073] The dosage of silica fume is 7%-10% of the cement weight.

[0074] The dosage of tannic acid is 0.2%-0.4% of the cement weight, preferably 0.2%-0.3% of the cement weight, and more preferably 0.3% of the cement weight.

[0075] The content of cellulose nanofibers is 0.08%-0.25% of the cement weight, preferably 0.08%-0.16% of the cement weight, and more preferably 0.16% of the cement weight.

[0076] The dosage of calcium hydroxide is 6%-9% of the cement weight.

[0077] The dosage of sodium carbonate is 3%-5% of the cement weight;

[0078] The water-cement ratio is 0.5;

[0079] The preparation method of the above-mentioned grouting material is as follows:

[0080] S1. Accurately weigh each raw material according to the proportion, dry mix cement, fly ash and silica fume to make the three substances evenly mixed, and obtain the composite cementitious base material of the grouting material.

[0081] S2. Divide the water into three equal parts by mass. Mix 1 / 3 of the water with tannic acid, stir well at a stirring speed of 300 rpm for 2 minutes to obtain a tannic acid solution.

[0082] S3. Mix 1 / 3 of the water with the cellulose nanofibers, stir evenly at a stirring speed of 500 rpm for 2 min to obtain a cellulose nanofiber solution. High-speed stirring allows the cellulose nanofibers to be initially dispersed, making it easier for tannic acid to be adsorbed on their surface in subsequent processes.

[0083] S4. Stir the cellulose nanofiber solution and tannic acid solution evenly at a stirring speed of 300 rpm for 2 min. After stirring, let stand for 3 min to obtain the first mixed solution. This allows tannic acid to be adsorbed on the surface of cellulose nanofibers, reducing the interaction between particles and thus promoting the further dispersion of cellulose nanofibers.

[0084] S5. Mix 1 / 3 of the water, sodium carbonate, and calcium hydroxide at a stirring speed of 300 rpm for 2 minutes to obtain a second mixed solution. The reaction of sodium carbonate and calcium hydroxide produces sodium hydroxide and calcium carbonate. Due to the high calcium hydroxide content, there will be excess calcium hydroxide. The generated sodium hydroxide and calcium hydroxide act as alkali activators, enhancing the reactivity of the internal fly ash. Simultaneously, calcium hydroxide provides a calcium source, promoting the formation of C(N)-ASH. The generated calcium carbonate can fill the pores inside the cement and can also undergo electrolysis to become calcium ions and carbonate ions, forming calcium aluminate. Since the decomposition temperature of calcium aluminate is higher than that of ettringite, it helps improve the high-temperature resistance of the grouting material.

[0085] S6. Pour the first mixed solution and the second mixed solution into the composite cementitious substrate material, stir evenly at a stirring speed of 300 rpm for 4 min, and obtain a high-temperature resistant, ultra-high flow nano-modified polymer grouting material.

[0086] S7. Place the prepared grouting material into curing chambers with different curing temperatures for curing to simulate a high ground temperature environment. After the corresponding time, take it out for subsequent experiments.

[0087] The high-temperature resistant, ultra-high-flow nano-modified polymer grouting material provided in this invention embodiment can be used for grouting in surrounding rock at high geothermal environments of 20-80℃.

[0088] In the embodiments of this invention, the curing temperature of the grouting material is designed for high geothermal environments in deep-ground engineering. There are two common grouting methods: direct grouting and pipeline grouting. Direct grouting involves bringing the grouting material to the grouting location and injecting it into the pores using equipment such as a grouting pump; the temperature of the injected grout is the same as the formation temperature. Pipeline grouting involves establishing a pipeline system on the surface and transporting the grouting material to the corresponding pores; the temperature of the injected grout gradually increases from the surface temperature to the formation temperature, exhibiting a temperature rise curve. Since the viscosity of the grouting material increases more rapidly at higher temperatures, meeting the grouting requirements at high temperatures also guarantees meeting the grouting requirements as the temperature gradually increases from the ground temperature to the high temperature. Therefore, the grouting material of this invention can be applied to high geothermal environments.

[0089] All raw materials used in the embodiments and comparative examples of this invention were purchased commercially. For example, the cement was P.O42.5 cement purchased from Zhucheng Yangchun Cement Co., Ltd.; the silica fume was Grade 96 silica fume purchased from Hengyuan New Materials Co., Ltd.; the fly ash was Grade III fly ash (325 mesh) selected from Yixiang New Materials Co., Ltd.; the cellulose nanofibers were a hydrogel solution purchased from Zhongshan Nanofiber Co., Ltd., with a mass percentage content of 2.5%; the tannic acid was purchased from Tianjin Zhonglian Chemical Reagent Co., Ltd.; the calcium hydroxide was purchased from Tianjin Huasheng Chemical Reagent Co., Ltd.; and the sodium carbonate was anhydrous sodium carbonate purchased from Tianjin Juhengda Chemical Co., Ltd.

[0090] Since the cellulose nanofibers obtained directly from the market are hydrogel solutions, and since the cellulose nanofibers themselves have a large aspect ratio and are not easy to use, the cellulose nanofibers are dissolved in water before use in this invention to facilitate subsequent use.

[0091] In this invention, the water-cement ratio is the weight ratio of water to cement, and is usually expressed by the formula: water-cement ratio = weight of water / weight of cement.

[0092] In this invention, unless otherwise specified, "parts" refers to "parts by weight".

[0093] The technical solution of the present invention will be further illustrated by the following embodiments.

[0094] Example 1

[0095] This embodiment provides a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material and its preparation method. The grouting material is made from the following raw materials in parts by weight:

[0096] The ingredients are: 500 parts cement, 375 parts fly ash, 42.5 parts silica fume, 37.5 parts calcium hydroxide, 20 parts sodium carbonate, 1.5 parts tannic acid, 0.8 parts cellulose nanofibers, and a water-cement ratio of 0.5.

[0097] The preparation method of the above-mentioned grouting material is as follows:

[0098] S1. Accurately weigh each raw material according to the proportion, dry mix cement, fly ash and silica fume to make the three substances evenly mixed, and obtain the composite cementitious base material of the grouting material.

[0099] S2. Divide the water into three equal parts by mass. Mix 1 / 3 of the water with tannic acid, stir well at a stirring speed of 300 rpm for 2 minutes to obtain a tannic acid solution.

[0100] S3. Mix 1 / 3 of the water with the cellulose nanofibers, stir evenly at a stirring speed of 500 rpm for 2 min to obtain a cellulose nanofiber solution. High-speed stirring allows the cellulose nanofibers to be initially dispersed, making it easier for tannic acid to be adsorbed on their surface in subsequent processes.

[0101] S4. Stir the cellulose nanofiber solution and tannic acid solution evenly at a stirring speed of 300 rpm for 2 min. After stirring, let stand for 3 min to obtain the first mixed solution. This allows tannic acid to be adsorbed on the surface of cellulose nanofibers, reducing the interaction between particles and thus promoting the further dispersion of cellulose nanofibers.

[0102] S5. Mix 1 / 3 of the water, sodium carbonate, and sodium hydroxide at a stirring speed of 300 rpm for 2 minutes to obtain a second mixed solution. Sodium carbonate and calcium hydroxide react to produce sodium hydroxide and calcium carbonate. Due to the high calcium hydroxide content, there will be excess calcium hydroxide. The generated sodium hydroxide and calcium hydroxide act as alkali activators, enhancing the reactivity of the internal fly ash. Simultaneously, calcium hydroxide provides a calcium source, promoting the formation of CSH. The generated calcium carbonate can fill the pores inside the cement and can also undergo electrolysis to convert into calcium ions and carbonate ions, forming calcium aluminate. Since the decomposition temperature of calcium aluminate is higher than that of ettringite, it helps improve the high-temperature resistance of the grouting material.

[0103] S6. Pour the first mixed solution and the second mixed solution into the composite cementitious substrate material, stir evenly at a stirring speed of 300 rpm for 4 min, and obtain a high-temperature resistant, ultra-high flow nano-modified polymer grouting material.

[0104] S7. The high-temperature resistant, ultra-high-flow nano-grouting material obtained in S6 is modified into polymer grouting material and placed in a curing chamber with a curing temperature of 20℃ (curing humidity of 98%) for curing until the corresponding age is reached. Then it is taken out for subsequent mechanical property testing and microscopic property testing.

[0105] Example 2

[0106] This embodiment provides a high-temperature resistant, ultra-high flow nano-modified polymer grouting material and its preparation method. The raw materials and preparation method of the grouting material are the same as in Example 1, except that the curing temperature in S7 is 50℃ (curing humidity is 90%).

[0107] Example 3

[0108] This embodiment provides a high-temperature resistant, ultra-high flow nano-modified polymer grouting material and its preparation method. The raw materials and preparation method of the grouting material are the same as in Example 1, except that the curing temperature in S7 is 80℃ (curing humidity is 80%).

[0109] Example 4

[0110] This embodiment provides a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material and its preparation method. The grouting material is made from the following raw materials in parts by weight:

[0111] The ingredients are: 500 parts cement, 350 parts fly ash, 35 parts silica fume, 30 parts calcium hydroxide, 15 parts sodium carbonate, 1 part tannic acid, 0.4 parts cellulose nanofibers, and a water-cement ratio of 0.5.

[0112] The preparation and curing methods of the high-temperature resistant, ultra-high flow nano-modified polymer grouting material in this embodiment are the same as in Example 1.

[0113] Example 5

[0114] This embodiment provides a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material and its preparation method. The grouting material is made from the following raw materials in parts by weight:

[0115] The ingredients are: 500 parts cement, 400 parts fly ash, 50 parts silica fume, 45 parts calcium hydroxide, 25 parts sodium carbonate, 2 parts tannic acid, 1.25 parts cellulose nanofibers, and a water-cement ratio of 0.5.

[0116] The preparation and curing methods of the high-temperature resistant, ultra-high flow nano-modified polymer grouting material in this embodiment are the same as in Example 1. The humidity values ​​in parentheses in Examples 1-3 represent the upper limit of humidity at the current temperature; differences in curing humidity do not affect the high-temperature resistance of the high-temperature resistant, ultra-high flow nano-modified polymer grouting material of this invention.

[0117] Comparative Example 1

[0118] Same as Example 1, except that tannic acid is not added.

[0119] Comparative Example 2

[0120] Same as Example 1, except that no cellulose nanofibers are added.

[0121] Comparative Example 3

[0122] Same as Example 2, except that tannic acid is not added.

[0123] Comparative Example 4

[0124] Same as Example 2, except that no cellulose nanofibers are added.

[0125] Comparative Example 5

[0126] Same as Example 3, except that tannic acid is not added.

[0127] Comparative Example 6

[0128] Same as Example 3, except that no cellulose nanofibers are added.

[0129] Comparative Example 7

[0130] Same as Example 1, except that no tannins and cellulose nanofibers are added.

[0131] Comparative Example 8

[0132] In this comparative example, the grouting material was made from the following raw materials in parts by weight: 500 parts cement, 375 parts fly ash, 42.5 parts silica fume, 37.5 parts calcium hydroxide, 20 parts sodium carbonate, 5 parts tannic acid, 0 parts cellulose nanofibers, and a water-cement ratio of 0.5.

[0133] The preparation and curing methods of the grouting material in this comparative example are the same as in Example 1.

[0134] Comparative Example 9

[0135] In this comparative example, the grouting material was made from the following raw materials in parts by weight: 500 parts cement, 375 parts fly ash, 42.5 parts silica fume, 37.5 parts calcium hydroxide, 20 parts sodium carbonate, 0 parts tannic acid, 3.2 parts cellulose nanofibers, and a water-cement ratio of 0.5.

[0136] The preparation and curing methods of the grouting material in this comparative example are the same as in Example 1.

[0137] The silicate hydration and aluminosilicate polymerization processes without tannins and cellulose nanofibers (i.e., Comparative Example 7) are shown below. Figure 1 The silicate hydration and aluminosilicate polymerization processes when tannic acid and cellulose nanofibers are added are described in [reference needed]. Figure 2 It can be observed that the cemented particles react immediately upon contact with water, generally by decomposing Ca within the particles. 2+ and SiO4 2-CSH gels are formed through hydration reactions with free water, or through polymerization reactions under alkaline activation, resulting in CASH gels. These processes fill pores and enhance strength. However, as the reaction progresses, some CSH gel adsorbs onto the particle surface, hindering further reaction. Therefore, in the later stages of hydration, incompletely hydrated particles and pores remain inside. When tannic acid and cellulose nanofibers are added, tannic acid can adsorb onto the surface of the cemented particles, forming a hydroxyl layer that hinders the absorption of calcium from the particles. 2+ and SiO4 2- Exudation occurs, and hydroxyl groups can react with Ca in the solution. 2+ and SiO4 2- The hydration reaction produces substances such as CSH, which coats the cemented particles with a gel layer, further hindering the internal Ca2+ formation. 2+ and SiO4 2- Exudation. Because the retarding of tannic acid requires Ca... 2+ The participation of [the agent / component] has little impact on the polymerization reaction and formation of CASH gel under alkali activation. At this point, the alkalinity of the solution system is controlled to prevent a rapid reaction, and the continuously generated CASH gel is sufficient to enhance the grouting material. For the specific reaction mechanism, see [link to relevant documentation]. Figure 3 and Figure 4 Meanwhile, since tannic acid particles can be adsorbed on the surface of cellulose nanofibers, reducing the interaction between particles and reducing agglomeration, cellulose nanofibers can better exert their bridging effect and fill the internal pores. Therefore, the porosity of cellulose nanofibers with added tannic acid and cellulose is lower in the later stage of hydration compared with that without added tannic acid and cellulose.

[0138] According to GB / T 1346 standard, the initial setting time, final setting time, initial fluidity, and fluidity after curing for 60, 120, and 180 min were tested. The compressive strength at 3 days, 7 days, and 14 days was tested according to GB / T 17671-2021. The test results are shown in Tables 1 and 2.

[0139] Table 1

[0140]

[0141] Table 2

[0142]

[0143] Figures 5-7XRD analysis revealed the hydration products generated in the grouting slurry under different curing days and temperatures. The results showed that calcium hydroxide (CH), quartz, and calcite had the highest diffraction peak intensities, indicating that these substances dominate the grouting slurry. Notably, no new diffraction peaks were observed despite the addition of tannic acid (TA) and cellulose nanofibers (CNFs), suggesting that these additives did not lead to the formation of new hydration products. The early hydration reaction rate of the grouting material could be assessed by analyzing the diffraction peaks of calcium hydroxide and quartz. Calcium hydroxide can undergo a secondary hydration reaction with the highly reactive silica within silica fume to generate calcium silicate hydrate, thereby improving the compressive strength of the grouting material. With prolonged curing time, the contents of calcium hydroxide and quartz gradually decreased, indicating that the rate of secondary hydration reaction was accelerating. This phenomenon suggests that with increasing curing age, calcium hydroxide and quartz in the grouting slurry participate in more secondary hydration reactions, leading to a decrease in their relative contents.

[0144] By comparing the XRD images of the grouting materials prepared in each example at different curing temperatures, it can be found that the content of calcium hydroxide and quartz in each example group decreases with increasing curing temperature. This indicates that the secondary hydration reaction rate inside the grouting material is faster with increasing curing temperature, resulting in higher strength of the grouting paste, which also corresponds to the results in the compressive strength section. Simultaneously, observing the amount of ettringite formed at different temperatures reveals that the ettringite content inside the grouting paste decreases with increasing curing temperature. The main reason for this is that ettringite decomposes at 60℃, undergoes significant thermal decomposition at 70-75℃, and becomes an amorphous structure at 80℃. Therefore, the lower peak value of ettringite in the corresponding XRD patterns confirms this conclusion.

[0145] Since calcium silicate hydrate is an amorphous gel, and XRD primarily observes the internal crystalline phase, observing calcium silicate hydrate is quite challenging. Because the main purpose of calcium silicate hydrate formation is to fill internal pores or cracks, the amount of calcium silicate hydrate formed can be determined by observing changes in porosity. To verify this theory, MIP data will be supplemented later for further validation.

[0146] The hydration reaction rate of the grouting material is relatively fast in the early stage, so the change in porosity is relatively more obvious. Therefore, this invention selected the porosity changes at 20℃, 50℃ and 80℃ at 3 days to verify the theory.

[0147] At temperatures below 40°C, the addition of cellulose nanofibers (CNFs) allows them to utilize their high aspect ratio and large specific surface area to more effectively fill pores and promote the formation of hydration products, thereby reducing pore size. For example... Figure 8 andFigure 9 As shown, the results of the mercury porosimetry test and Figure 5 The XRD analysis results of Comparative Example 2 and Example 1 are consistent. Conversely, the addition of tannic acid leads to an increase in porosity. This is mainly because the adsorption and retarding effects of tannic acid reduce the formation of early hydration products, preventing the formation of hydration products that should have blocked the pores, thus increasing porosity. This is consistent with the higher peak values ​​of C3S and C2S in the XRD results above, indicating that the addition of tannic acid affects the formation of products during the hydration process of the grouting material.

[0148] When the curing temperature is above 50℃, it can be found that the porosity of the group with tannic acid and cellulose nanofibers is lower than that of the group with cellulose nanofibers alone (see...). Figures 10-13 The main reason for this is that at higher temperatures, the hydration reaction inside the grouting material accelerates, leading to excessive heat of hydration and insufficient time for orderly sedimentation. This can cause hydration products to overlap and become disordered, resulting in excessive micropores and reduced strength in later stages. However, tannic acid slows down the hydration reaction of the grouting material, reducing the early heat of hydration and decreasing the number of pores, thus helping to optimize its internal porosity. This also corresponds to the results of the early compressive strength in Table 1.

[0149] Because hydrated calcium silicate exhibits different morphologies under different curing ages and conditions, its strength enhancement can be categorized into three types from high to low: clustered, network, and needle-like. To confirm the morphology of the hydrated calcium silicate filling the pores within the grouting material, this invention will observe the morphology of the internal hydrated calcium silicate and other substances to confirm its developmental form. Simultaneously, by observing the internal pores and comparing them with MIP data (i.e.,...),... Figures 8-13 Consistent.

[0150] Figures 14-22 The SEM images primarily compare the distribution of hydration products and pores inside the fly ash at different curing temperatures over 3 days. It can be observed that at a curing temperature of 20℃, the sample exhibits a loose and porous structure, with the internal hydrated calcium silicate mainly needle-like, and only a small portion of the hydration products adsorbed on the fly ash surface. This is mainly due to the retarding effect of tannic acid, which reduces the hydration reaction rate and consequently decreases the number of hydration products. At curing temperatures of 50℃ and 80℃, the number of internal hydration products increases significantly, with some fly ash surfaces even completely coated with CSH and CASH. The number of needle-like hydration products inside also decreases significantly. This is partly because ettringite decomposes at temperatures above 50℃ (however, the CASH adsorbed on the fly ash (aluminum-rich material) surface has strong high-temperature resistance and does not decompose at 80℃; the morphology of ettringite on the aluminum-rich material (fly ash) surface is shown in [image missing]. Figure 23The main reason for this is that the mineral components inside fly ash undergo alkali-activated polymerization to form a polymer structure, making it more resistant to high temperatures. On the other hand, some CSH also transforms from needle-like to clustered or mesh-like structures, resulting in a more significant improvement in strength. Comparing Comparative Example 6 and Example 3 at a curing temperature of 80℃, it can be found that the porosity of Example 3 is significantly lower than that of Comparative Example 4. This also demonstrates that tannic acid can indeed reduce the phenomenon of excessively rapid hydration leading to increased rough porosity at high temperatures, which corresponds to the compressive strength results in Table 1.

[0151] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-temperature resistant, ultra-high-flow nano-modified polymer grouting material, characterized in that, It is composed of the following raw materials: cement, fly ash, silica fume, calcium hydroxide, sodium carbonate, tannic acid, cellulose nanofibers and water; Based on the weight percentage of cement, the dosages of other components are as follows: The amount of fly ash added should be 70%-80% of the weight of cement. The amount of silica fume added is 7%-10% of the cement weight. The dosage of tannic acid is 0.2%-0.4% of the cement weight. The dosage of cellulose nanofibers is 0.08%-0.25% of the cement weight. The dosage of calcium hydroxide is 6%-9% of the cement weight. The dosage of sodium carbonate is 3%-5% of the cement weight; The water-cement ratio is 0.

5.

2. The high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to claim 1, characterized in that, The amount of tannic acid is 0.2%-0.3% of the cement weight, and the amount of cellulose nanofibers is 0.08%-0.16% of the cement weight.

3. The high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to claim 2, characterized in that, The amount of tannic acid added is 0.3% of the weight of cement, and the amount of cellulose nanofiber added is 0.16% of the weight of cement.

4. A method for preparing a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Accurately weigh each raw material according to the proportion, dry mix cement, fly ash and silica fume to make the three substances evenly mixed, and obtain the composite cementitious base material of the grouting material. S2. Divide the water into three equal parts by mass, mix 1 / 3 of the water with tannic acid, stir well to obtain a tannic acid solution; S3. Mix 1 / 3 of the water with the cellulose nanofibers and stir until homogeneous to obtain a cellulose nanofiber solution; S4. Stir the cellulose nanofiber solution and tannic acid solution evenly, and let stand after stirring to obtain the first mixed solution; S5. Mix 1 / 3 of the water, sodium carbonate, and calcium hydroxide to obtain a second mixed solution; S6. Pour the first mixed solution and the second mixed solution into the composite cementitious substrate material and stir evenly to obtain a high-temperature resistant, ultra-high-flow nano-modified polymer grouting material.

5. The preparation method of the high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to claim 4, characterized in that, In step S2, the stirring speed is 300 rpm and the stirring time is 2 min.

6. The preparation method of the high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to claim 4, characterized in that, In step S3, the stirring speed is 500 rpm and the stirring time is 2 min.

7. The preparation method of the high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to claim 4, characterized in that, In step S4, the stirring speed is 300 rpm and the stirring time is 2 min; In step S5, the stirring speed is 300 rpm and the stirring time is 2 min.

8. The preparation method of the high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to claim 4, characterized in that, In step S6, the stirring speed is 300 rpm and the stirring time is 4 min.

9. The application of the high-temperature resistant, ultra-high-flow nano-modified polymer grouting material according to any one of claims 1-3 in grouting of surrounding rock in high-temperature environments, characterized in that, The high geothermal environment is 40-80℃.

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