A low water absorption coal gangue roadbed filler and preparation method thereof

Abstract

The invention discloses a low-water-absorption coal gangue roadbed filler and a preparation method thereof, relating to the technical field of roadbed fillers. The raw materials include: coal gangue, lignin, starch, water glass, modified polybenzimidazole, nano-silica, chitosan, phosphogypsum, and aluminum sulfate. 4,4'-bisazidobiphenyl and perfluoroalkyl propylene oxide are introduced into the modified polybenzimidazole, and the 4,4'-bisazidobiphenyl undergoes an addition reaction to preferentially form a three-dimensional topological cross-linked network structure at the ring ortho position of the polybenzimidazole, thereby increasing the cross-linking density and enhancing the strength performance. The perfluoroalkyl propylene oxide significantly improves the hydrophobicity of the polybenzimidazole. The hydrogen bonds in the modified polybenzimidazole can be cross-linked with the lignin and starch to form an interpenetrating network structure, thereby further enhancing the density of the covering layer on the surface of the coal gangue. At the same time, since the modified polybenzimidazole has high strength and super-hydrophobicity, the waterproof performance and strength performance of the coal gangue particles can be further improved.

Description

Technical Field

[0001] The invention relates to the technical field of roadbed fillers, and in particular to a low-water-absorption coal gangue roadbed filler and a preparation method thereof. Background Art

[0002] Gangue is a solid waste generated during coal mining and processing. Gangue is typically gray or black and primarily composed of minerals such as silica, bauxite, and iron ore. It also contains certain harmful components, such as sulfides and heavy metals. Because gangue is difficult to degrade naturally and has strong hygroscopicity and expansibility, directly storing untreated gangue not only occupies a large amount of land but also produces harmful substances through infiltration and weathering, polluting water, air, and soil, and placing certain pressures on the environment.

[0003] Gangue has potential applications in many fields, particularly in roadbed filling, cement production, brick and tile manufacturing, and soil improvement, where it has seen initial application. Gangue is widely used as a filler material in roadbed construction, its low cost and abundant resources making it an ideal alternative. However, due to its strong water absorption and swelling properties, gangue is prone to swelling in humid environments or when exposed to moisture for long periods of time. This can lead to loose filler, reduced roadbed strength, and compromised long-term stability.

[0004] Currently, methods for modifying coal gangue primarily focus on improving its water absorption and expansion properties through the use of single modifiers such as lime and cement. While these methods can improve the performance of coal gangue in the short term, they suffer from issues such as short-term effects and persistently high water absorption and expansion properties. Especially in long-term humid environments, the performance of coal gangue still fails to meet the requirements of high-strength roadbeds. Furthermore, some modification methods suffer from drawbacks such as complex operation, high costs, and limited improvement in material strength after modification, hindering their widespread adoption.

[0005] In recent years, with increasingly stringent environmental protection policies and growing demand for resource utilization, the efficient utilization of coal gangue has become a pressing issue. Improving the performance of coal gangue through modification not only mitigates its potential environmental hazards but also enhances its application in projects such as roadbed filling, promoting its resource utilization and industrial development. While existing modification technologies have made some progress, most methods still cannot simultaneously address water absorption and strength issues, and the modification results vary widely, making it difficult to meet the actual needs of different projects. Summary of the Invention

[0006] The purpose of the present invention is to provide a low water absorption coal gangue roadbed filler and a preparation method thereof, so as to solve the following technical problems:

[0007] How to improve the water resistance and strength performance of coal gangue roadbed filling.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] In a first aspect, the present invention discloses a low-water-absorption coal gangue roadbed filler, comprising the following raw materials in parts by weight: 40-50 parts of coal gangue, 5-12 parts of lignin, 5-12 parts of starch, 3-5 parts of water glass, 2-5 parts of modified polybenzimidazole, 0.5-1 part of nano-silica, 0.5-1 part of chitosan, 1-2 parts of phosphogypsum, and 0.5-1 part of aluminum sulfate;

[0010] Preferably, the low water absorption coal gangue roadbed filler comprises the following raw materials in parts by weight: 42-48 parts of coal gangue, 8-11 parts of lignin, 8-11 parts of starch, 4 parts of water glass, 4 parts of modified polybenzimidazole, 0.6-0.9 parts of nano-silica, 0.6-0.9 parts of chitosan, 1.2-1.8 parts of phosphogypsum, and 0.6-0.9 parts of aluminum sulfate.

[0011] More preferably, the low water absorption coal gangue roadbed filler comprises the following raw materials in parts by weight: 45 parts of coal gangue, 10 parts of lignin, 10 parts of starch, 4 parts of water glass, 4 parts of modified polybenzimidazole, 0.8 parts of nano-silica, 0.8 parts of chitosan, 1.5 parts of phosphogypsum, and 0.8 parts of aluminum sulfate.

[0012] Furthermore, the preparation method of the modified polybenzimidazole is:

[0013] Step A1: dissolving polybenzimidazole in a solvent, adding 4,4'-bis(azide)biphenyl and a template, mixing evenly, spreading on a substrate, and irradiating with ultraviolet light to obtain a polybenzimidazole film.

[0014] Preferably, the specific operation method of step A1 is: dissolving polybenzimidazole in a solvent, heating to 75°C under nitrogen protection, and then magnetically stirring at 500 rpm for 6 hours to form a transparent solution, then adding 4,4'-bisazide biphenyl and a template, stirring at a speed of 300 rpm for 2 hours to mix them evenly, and then spreading them on a substrate and irradiating them with ultraviolet light to obtain a polybenzimidazole film; wherein, under nitrogen protection, solvent oxidation can be prevented, and temperature control at 75°C can avoid degradation of polybenzimidazole; under ultraviolet irradiation, 4,4'-bisazide biphenyl undergoes an addition reaction, preferentially forming a three-dimensional topological cross-linked network structure at the ortho position of the ring of polybenzimidazole, thereby increasing its cross-linking density and enhancing its strength performance.

[0015] Step A2: adding perfluoroalkyl propylene oxide and boric acid to anhydrous ethanol and mixing them evenly to form a fluorinated liquid; then crushing the polybenzimidazole film into powder and immersing it in the fluorinated liquid for heat treatment; washing and drying the powder to obtain a modified polybenzimidazole.

[0016] Preferably, the specific operation method of step A2 is: adding perfluoroalkyl propylene oxide and boric acid to anhydrous ethanol, ultrasonically treating them at a frequency of 40 Hz for 15 minutes to mix them evenly to form a fluorinated liquid, and then adding the polybenzimidazole film to a crusher to crush it into a powder with a particle size of 0.01-0.1 mm, immersing it in a fluorinated liquid and stirring it at 200-500 rpm for 20 minutes, and then heat treating it. During the heat treatment, the epoxy group of the perfluoroalkyl propylene oxide and the residual amino group of the polybenzimidazole side chain undergo a ring-opening reaction, so that the perfluoroalkyl propylene oxide is grafted on the polybenzimidazole, thereby greatly improving the hydrophobicity of the polybenzimidazole and achieving a superhydrophobic state. At the same time, boric acid acts as a catalyst to form a borate bond, which is reversibly broken / recombined in a hot and humid environment, thereby avoiding interfacial cracking caused by stress concentration; after the heat treatment is completed, it is repeatedly washed with ethanol 3-5 times, and then placed in a vacuum drying oven at 60 ° C. and vacuum dried for 2 hours to finally obtain a modified polybenzimidazole.

[0017] Preferably, in step A1, the mass fraction of the polybenzimidazole in the solvent is 12-18 wt %;

[0018] More preferably, in step A1, the mass fraction of the polybenzimidazole in the solvent is 15 wt %.

[0019] Preferably, in step A1, the solvent is N,N-dimethylacetamide.

[0020] Preferably, in step A1, the ratio of the added weight of the 4,4'-bisazidebiphenyl to the added weight of the polybenzimidazole is 1:6.

[0021] Preferably, in step A1, the weight ratio of the template to the polybenzimidazole is 1:30.

[0022] Preferably, the template is biphenyltetracarboxylic dianhydride, which guides the orderly arrangement of cross-linking sites through π-π stacking during the reaction, so that the cross-linking sites can avoid the original NH hydrogen bond donor sites and retain the hydrogen bond network between the benzimidazole rings.

[0023] Preferably, in step A1, the specific operation method of spreading the mixed solution on the substrate and irradiating with ultraviolet light is as follows: casting the mixed solution on a glass plate, controlling the casting thickness to 80-150nm with a scraper, and then irradiating the solution with a wavelength of 365nm and an intensity of 25-50mW / cm 2 UV irradiation for 0.5h is enough;

[0024] More preferably, in step A1, the mixed solution is spread on the substrate and irradiated with ultraviolet light as follows: the mixed solution is cast on a glass plate, the casting thickness is controlled to 100 nm with a scraper, and then the solution is irradiated with a wavelength of 365 nm and an intensity of 35 mW / cm 2 UV irradiation for 0.5h is sufficient.

[0025] Preferably, in step A2, the mass fraction of perfluoroalkyl propylene oxide in the fluorinated liquid is 5-10 wt %;

[0026] More preferably, in step A2, the mass fraction of perfluoroalkyl propylene oxide in the fluorinated liquid is 8 wt %.

[0027] Preferably, in step A2, the mass fraction of boric acid in the fluorination liquid is 0.3 wt %.

[0028] Preferably, in step A2, the specific operation of the heat treatment is: first heating at 120° C. for 10 minutes, then cooling to 80° C. and keeping warm for 20 minutes.

[0029] Based on this, a preferred method for preparing modified polybenzimidazole is obtained, comprising the following steps:

[0030] Step a1, polybenzimidazole is dissolved in N,N-dimethylacetamide, the mass fraction of polybenzimidazole in the solvent is 15wt%, and under nitrogen protection, it is heated to 75 ° C and magnetically stirred at 500 rpm for 6 hours to form a transparent solution, and then 4,4'-bisazidobiphenyl and biphenyltetracarboxylic dianhydride are added, the added weight ratio of 4,4'-bisazidobiphenyl to the added weight of polybenzimidazole is 1:6, and the added weight ratio of biphenyltetracarboxylic dianhydride to polybenzimidazole is 1:30, and then stirred at a speed of 300 rpm for 2 hours to mix it evenly, and then cast on a glass plate, and the casting thickness is controlled to 100 nm with a scraper, and then the wavelength is 365 nm and the light intensity is 35 mW / cm 2 The polybenzimidazole film was obtained by irradiating the film with ultraviolet light for 0.5 h.

[0031] Step a2, adding perfluoroalkyl propylene oxide and boric acid to anhydrous ethanol, ultrasonically treating at a frequency of 40 Hz for 15 minutes to mix them evenly, to form a fluorinated liquid, wherein the mass fraction of perfluoroalkyl propylene oxide in the fluorinated liquid is 8wt%, and the mass fraction of boric acid is 0.3wt%; then adding the polybenzimidazole film to a crusher to crush it into a powder with a particle size of 0.01-0.1 mm, and then immersing it in the fluorinated liquid and stirring it at 300 rpm for 20 minutes, then placing it in an oven, first heating it at 120°C for 10 minutes, then cooling it to 80°C and keeping it warm for 20 minutes, taking it out and repeatedly washing it with ethanol 3-5 times, and then placing it in a vacuum drying oven at 60°C for 2 hours to finally obtain a modified polybenzimidazole.

[0032] In a second aspect, the present invention further discloses a method for preparing the low water absorption coal gangue roadbed filler as described above, comprising the following steps:

[0033] Step 1. Weigh the raw materials in proportion by weight, add the coal gangue, nano-silica, phosphogypsum and aluminum sulfate into a high-speed mixer and dry-mix at 500 rpm for 15 minutes to obtain a premix; during this process, the calcium ions in the phosphogypsum combine with the aluminosilicates in the coal gangue to generate hydration products, which can strengthen the bonding between the coal gangue particles and inhibit expansion; the nano-silica is dispersed in the hydration products, enhancing the bonding strength between the coal gangue particles, and the aluminum sulfate is adsorbed on the surface of the coal gangue particles as an electrolyte, which can reduce the electrostatic repulsion between the particles.

[0034] Step 2: Dissolve lignin, starch and chitosan in an acetic acid solution with a pH of 3-4 and stir evenly, then add water glass and stir at 50°C until the solution becomes gel-like. During this process, the amino groups in chitosan are cross-linked with the phenolic hydroxyl groups of lignin and the hydroxyl groups of starch through hydrogen bonds to form a three-dimensional network structure; the water glass provides alkaline silicate ions, which produce electrostatic attraction with the amino groups of chitosan, thereby enhancing the stability of the gel; then add the premix in small amounts and stir evenly to form a sol; the aluminum sulfate in the premix will react with the water glass to generate aluminosilicate gel, fill the gaps between the particles, and reduce the porosity. At the same time, the three-dimensional network structure formed by chitosan, lignin and starch covers the surface of the coal gangue to form a dense covering layer, which is waterproof and enhances the strength of the coal gangue.

[0035] Step 3: Add the modified polybenzimidazole to the sol and stir the reaction at 55-65°C for 0.5-1h to form agglomerates; during this process, the hydrogen bonds in the modified polybenzimidazole will cross-link with lignin and starch to form an interpenetrating network structure, further enhancing the density of the covering layer on the surface of the coal gangue. At the same time, since the modified polybenzimidazole has high strength and superhydrophobic properties, it can further improve the waterproof and strength properties of the coal gangue particles.

[0036] Step 4: Place the agglomerate in a mold, press it into shape at a pressure of 18-25 MPa, then heat cure it in an atmosphere of 80-100°C for 24 hours, and finally cure it at a room temperature of 25-30°C for 7 days to obtain a low-water-absorption coal gangue roadbed filler.

[0037] Furthermore, the gangue needs to be pretreated before being weighed, and the pretreatment method is as follows: crushing the gangue raw material to a particle size of ≤5 mm, reducing the particle size, increasing the bulk density, and reducing the internal porosity; then screening to remove impurities, calcining at 200°C for 2h to remove internal moisture, enhance material stability, and prevent water absorption and expansion in the later stage, and then cooling for use.

[0038] Based on this, a preferred method for preparing a low-water-absorbent coal gangue roadbed filler is obtained, comprising the following steps:

[0039] Step 1: After pre-treating the coal gangue, the raw materials were weighed according to the weight ratio, and the coal gangue, nano-silica, phosphogypsum and aluminum sulfate were added into a high-speed mixer and dry-mixed at 500 rpm for 15 minutes to obtain a premix;

[0040] Step 2: dissolving lignin, starch and chitosan in an acetic acid solution with a pH of 3-4 and stirring evenly. The amount of acetic acid solution is 4 times the total weight of lignin, starch and chitosan. Then, water glass is added and stirred at 50°C until the solution becomes a gel. Then, the premix is added in equal amounts in 3-5 times and stirred evenly to form a sol.

[0041] Step 3, adding the modified polybenzimidazole to the sol, stirring and reacting at 55-65° C. for 0.5-1 h to form agglomerates;

[0042] Step 4: Place the agglomerate in a mold, press it into shape at a pressure of 20 MPa, then heat cure it at 90°C for 24 hours, and finally cure it at room temperature of 25-30°C for 7 days to obtain a low-water-absorption coal gangue roadbed filler.

[0043] Beneficial effects of the present invention:

[0044] 1. The low-water-absorption coal gangue roadbed filler of the present invention comprises coal gangue, nano-silica, phosphogypsum and aluminum sulfate. The calcium ions in the phosphogypsum combine with the aluminosilicates in the coal gangue to generate hydration products, which can strengthen the bonding between the coal gangue particles and inhibit expansion. The nano-silica is dispersed in the hydration products, enhancing the bonding strength between the coal gangue particles. The aluminum sulfate acts as an electrolyte and is adsorbed on the surface of the coal gangue particles, which can reduce the electrostatic repulsion between the particles and make the system more stable.

[0045] 2. The low-water-absorbent coal gangue roadbed filler of the present invention further comprises lignin, starch, chitosan and water glass, wherein the amino groups in chitosan are cross-linked with the phenolic hydroxyl groups of lignin and the hydroxyl groups of starch through hydrogen bonds to form a three-dimensional network structure; the water glass provides alkaline silicate ions, which generate electrostatic attraction with the amino groups of chitosan, thereby enhancing the stability of the gel; the aluminum sulfate in the premix reacts with the water glass to generate aluminosilicate gel, which fills the gaps between the particles and reduces the porosity. At the same time, the three-dimensional network structure formed by the chitosan, lignin and starch covers the surface of the coal gangue to form a dense covering layer, which is waterproof and enhances the strength of the coal gangue.

[0046] 3. The low water absorption coal gangue roadbed filler of the present invention further adds modified polybenzimidazole, wherein 4,4'-bisazidobiphenyl is introduced. Under ultraviolet irradiation, 4,4'-bisazidobiphenyl undergoes addition reaction, preferentially forming a three-dimensional topological cross-linked network structure at the ortho position of the polybenzimidazole ring, thereby increasing its cross-linking density and enhancing its strength performance; perfluoroalkyl propylene oxide is also introduced, and its epoxy group undergoes ring-opening reaction with the residual amino group of the polybenzimidazole side chain, so that the perfluoroalkyl propylene oxide is grafted on the polybenzimidazole, making the poly The hydrophobicity of benzimidazole is greatly improved, reaching a superhydrophobic state. At the same time, boric acid acts as a catalyst to form borate bonds. The borate bonds can reversibly break / reorganize in a humid and hot environment, which can avoid interfacial cracking caused by stress concentration. The hydrogen bonds in the modified polybenzimidazole will cross-link with lignin and starch to form an interpenetrating network structure, further enhancing the density of the covering layer on the surface of the coal gangue. At the same time, because the modified polybenzimidazole has high strength and superhydrophobic properties, it can further improve the waterproof and strength properties of the coal gangue particles. DETAILED DESCRIPTION

[0047] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0048] The experimental methods in the following examples, unless otherwise specified, are all conventional methods and are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples, unless otherwise specified, can be obtained from commercial sources. For example, the types and sources of the raw materials involved in the preparation examples, examples, and comparative examples are shown in Table 1, which is as follows:

[0049] Table 1

[0050]

[0051] Preparation Example 1

[0052] Preparation of modified polybenzimidazole:

[0053] Step a1, polybenzimidazole is dissolved in N,N-dimethylacetamide, the mass fraction of polybenzimidazole in the solvent is 15wt%, and under nitrogen protection, it is heated to 75 ° C and magnetically stirred at 500 rpm for 6 hours to form a transparent solution, and then 4,4'-bisazidobiphenyl and biphenyltetracarboxylic dianhydride are added, the added weight ratio of 4,4'-bisazidobiphenyl to the added weight of polybenzimidazole is 1:6, and the added weight ratio of biphenyltetracarboxylic dianhydride to polybenzimidazole is 1:30, and then stirred at a speed of 300 rpm for 2 hours to mix it evenly, and then cast on a glass plate, and the casting thickness is controlled to 100 nm with a scraper, and then the wavelength is 365 nm and the light intensity is 35 mW / cm 2 The polybenzimidazole film was obtained by irradiating the film with ultraviolet light for 0.5 h.

[0054] Step a2, adding perfluoroalkyl propylene oxide and boric acid to anhydrous ethanol, ultrasonically treating at a frequency of 40 Hz for 15 minutes to mix them evenly, to form a fluorinated liquid, wherein the mass fraction of perfluoroalkyl propylene oxide in the fluorinated liquid is 8wt%, and the mass fraction of boric acid is 0.3wt%; then adding the polybenzimidazole film to a crusher to crush it into a powder with a particle size of 0.01-0.1 mm, and then immersing it in the fluorinated liquid and stirring it at 300 rpm for 20 minutes, then placing it in an oven, first heating it at 120°C for 10 minutes, then cooling it to 80°C and keeping it warm for 20 minutes, taking it out and repeatedly washing it with ethanol three times, and then placing it in a vacuum drying oven at 60°C for 2 hours to finally obtain a modified polybenzimidazole.

[0055] Comparative Preparation Example 1

[0056] Preparation of modified polybenzimidazole:

[0057] Compared with Preparation Example 1, the only difference is that in step a1, biphenyltetracarboxylic dianhydride is omitted, and other steps and conditions remain the same; finally, modified polybenzimidazole is obtained.

[0058] Comparative Preparation Example 2

[0059] Preparation of modified polybenzimidazole:

[0060] Compared with Preparation Example 1, the only difference is that step a1 is eliminated, and the polybenzimidazole membrane is replaced by polybenzimidazole in step a2; the other steps and conditions remain the same, and modified polybenzimidazole is finally obtained.

[0061] Comparative Preparation Example 3

[0062] Preparation of modified polybenzimidazole:

[0063] Compared with Preparation Example 1, the only difference is that step a2 is omitted, and at the end of step a1, the polybenzimidazole film is added to a crusher and crushed into powder with a particle size of 0.01-0.1 mm; other steps and conditions remain the same, and modified polybenzimidazole is finally obtained.

[0064] Example 1

[0065] This embodiment discloses a low-water-absorption coal gangue roadbed filler, comprising the following raw materials in parts by weight: 45 parts of coal gangue, 10 parts of lignin, 10 parts of starch, 4 parts of water glass, 4 parts of modified polybenzimidazole of Preparation Example 1, 0.8 parts of nano-silicon dioxide, 0.8 parts of chitosan, 1.5 parts of phosphogypsum, and 0.8 parts of aluminum sulfate. The raw materials are prepared according to the above raw materials and weight proportions, and the low-water-absorption coal gangue roadbed filler is prepared, comprising the following steps:

[0066] Step 1: adding coal gangue, nano-silica, phosphogypsum and aluminum sulfate into a high-speed mixer and dry-mixing at 500 rpm for 15 minutes to obtain a premix;

[0067] Step 2: Add 4 times the total weight of lignin, starch and chitosan to a blender. The pH = 4 acetic acid solution is dissolved in the acetic acid solution and stirred evenly. Then, water glass is added and stirred at 50 ° C until the solution becomes a gel. Then, the premix is added in equal amounts in three times and stirred evenly to form a sol.

[0068] Step 3, adding the modified polybenzimidazole to the sol, stirring and reacting at 60° C. for 40 minutes to form agglomerates;

[0069] Step 4: Place the agglomerate in a mold, press it into shape at a pressure of 20 MPa, then heat cure it at 90°C for 24 hours, and finally cure it at room temperature of 25°C for 7 days to obtain a low-water-absorbent coal gangue roadbed filler.

[0070] Example 2

[0071] This embodiment discloses a low-water-absorption coal gangue roadbed filler, comprising the following raw materials in parts by weight: 42 parts of coal gangue, 8 parts of lignin, 8 parts of starch, 4 parts of water glass, 4 parts of modified polybenzimidazole of Preparation Example 1, 0.6 parts of nano-silica, 0.6 parts of chitosan, 1.2 parts of phosphogypsum, and 0.6 parts of aluminum sulfate. The raw materials are prepared according to the above raw materials and weight ratios, and the low-water-absorption coal gangue roadbed filler is prepared. The preparation method is exactly the same as the preparation method of the low-water-absorption coal gangue roadbed filler in Example 1, and finally the low-water-absorption coal gangue roadbed filler is prepared.

[0072] Example 3

[0073] This embodiment discloses a low-water-absorption coal gangue roadbed filler, comprising the following raw materials in parts by weight: 48 parts of coal gangue, 11 parts of lignin, 11 parts of starch, 4 parts of water glass, 4 parts of modified polybenzimidazole of Preparation Example 1, 0.9 parts of nano-silica, 0.9 parts of chitosan, 1.8 parts of phosphogypsum, and 0.9 parts of aluminum sulfate. The raw materials are prepared according to the above raw materials and weight ratios, and the low-water-absorption coal gangue roadbed filler is prepared. The preparation method is exactly the same as the preparation method of the low-water-absorption coal gangue roadbed filler in Example 1, and finally the low-water-absorption coal gangue roadbed filler is prepared.

[0074] Example 4

[0075] This embodiment discloses a low-water-absorption coal gangue roadbed filler, comprising the following raw materials in parts by weight: 40 parts of coal gangue, 5 parts of lignin, 5 parts of starch, 3 parts of water glass, 2 parts of modified polybenzimidazole of Preparation Example 1, 0.5 parts of nano-silica, 0.5 parts of chitosan, 1 part of phosphogypsum, and 0.5 parts of aluminum sulfate. The raw materials are prepared according to the above raw materials and weight ratios, and the low-water-absorption coal gangue roadbed filler is prepared. The preparation method is exactly the same as the preparation method of the low-water-absorption coal gangue roadbed filler in Example 1, and finally the low-water-absorption coal gangue roadbed filler is prepared.

[0076] Example 5

[0077] This embodiment discloses a low-water-absorption coal gangue roadbed filler, comprising the following raw materials in parts by weight: 50 parts of coal gangue, 12 parts of lignin, 12 parts of starch, 5 parts of water glass, 5 parts of modified polybenzimidazole of Preparation Example 1, 1 part of nano-silica, 1 part of chitosan, 2 parts of phosphogypsum, and 1 part of aluminum sulfate. The raw materials are prepared according to the above raw materials and weight ratios, and the low-water-absorption coal gangue roadbed filler is prepared. The preparation method is exactly the same as the preparation method of the low-water-absorption coal gangue roadbed filler in Example 1, and finally the low-water-absorption coal gangue roadbed filler is prepared.

[0078] Comparative Example 1

[0079] Compared with Example 1, the only difference is that the modified polybenzimidazole of Preparation Example 1 is replaced by the modified polybenzimidazole of Comparative Preparation Example 1, and other conditions remain the same, and finally a coal gangue roadbed filler is prepared.

[0080] Comparative Example 2

[0081] Compared with Example 1, the only difference is that the modified polybenzimidazole of Preparation Example 1 is replaced by the modified polybenzimidazole of Comparative Preparation Example 2, and other conditions remain the same, and finally a coal gangue roadbed filler is prepared.

[0082] Comparative Example 3

[0083] Compared with Example 1, the only difference is that the modified polybenzimidazole of Preparation Example 1 is replaced by the modified polybenzimidazole of Comparative Preparation Example 3, and other conditions remain the same, and finally a coal gangue roadbed filler is prepared.

[0084] Comparative Example 4

[0085] Compared with Example 1, the only difference is that the modified polybenzimidazole in Preparation Example 1 is replaced by the purchased polybenzimidazole raw material, and other conditions remain the same, and finally a coal gangue roadbed filler is prepared.

[0086] The performance tests of the gangue roadbed fillers of Examples 1-5 and Comparative Examples 1-4 were conducted, including water resistance test and strength test, and the test methods were as follows:

[0087] Water absorption rate: refer to the "Water absorption rate test of soil" in GB / T 50123-2019 "Standard for geotechnical test methods";

[0088] Unconfined compressive strength: refer to GB / T 50123-2019 test standard;

[0089] California bearing ratio: refer to JTG E40-2007 "Highway Geotechnical Test Code".

[0090] The test results are listed in Table 2, which is as follows:

[0091] Table 2

[0092]

[0093] By analyzing the data in Table 2, it can be seen that compared with Comparative Examples 1-4, the coal gangue roadbed fillers of Examples 1-5 have stronger water resistance and strength performance, and can be used as preferred materials for roadbed fillers.

[0094] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A low water absorption coal gangue roadbed filler, characterized in that: The invention comprises the following raw materials in parts by weight: 40-50 parts of coal gangue, 5-12 parts of lignin, 5-12 parts of starch, 3-5 parts of water glass, 2-5 parts of modified polybenzimidazole, 0.5-1 part of nano-silicon dioxide, 0.5-1 part of chitosan, 1-2 parts of phosphogypsum, and 0.5-1 part of aluminum sulfate; Wherein, the preparation method of the modified polybenzimidazole is: Step A1, dissolving polybenzimidazole in a solvent, adding 4,4'-bis(azide)biphenyl and a template, mixing evenly, spreading on a substrate, and irradiating with ultraviolet light to obtain a polybenzimidazole film; Step A2: adding perfluoroalkyl propylene oxide and boric acid to anhydrous ethanol and mixing them uniformly to form a fluorinated liquid; then crushing the polybenzimidazole film into powder and immersing it in the fluorinated liquid for heat treatment; washing and drying the powder to obtain a modified polybenzimidazole; The preparation method of the low water absorption coal gangue roadbed filler comprises the following steps: Step 1: weighing raw materials in parts by weight, dry-mixing coal gangue, nano-silicon dioxide, phosphogypsum and aluminum sulfate to obtain a premix; Step 2: dissolve lignin, starch and chitosan in an acetic acid solution with a pH of 3-4 and stir evenly, then add water glass and stir at 50°C until the solution becomes gel-like, then add the premix in small amounts and stir evenly to form a sol; Step 3: Add the modified polybenzimidazole to the sol, stir and react at 55-65°C for 0.5-1h to form agglomerates; Step 4: Place the agglomerate in a mold, press it into shape at a pressure of 18-25 MPa, then heat cure it in an atmosphere of 80-100°C for 24 hours, and finally cure it at a room temperature of 25-30°C for 7 days to obtain a low-water-absorption coal gangue roadbed filler.

2. The low water absorption coal gangue roadbed filler according to claim 1, characterized in that: In step A1, the mass fraction of the polybenzimidazole in the solvent is 12-18 wt %.

3. The low water absorption coal gangue roadbed filler according to claim 2, characterized in that: The solvent is N,N-dimethylacetamide.

4. The low water absorption coal gangue roadbed filler according to claim 1, characterized in that: In step A1, the ratio of the added weight of the 4,4'-bisazidebiphenyl to the added weight of the polybenzimidazole is 1:

6.

5. The low water absorption coal gangue roadbed filler according to claim 1, characterized in that: In step A1, the weight ratio of the template to polybenzimidazole is 1:

30.

6. The low water absorption coal gangue roadbed filler according to claim 5, characterized in that: The template agent is biphenyltetracarboxylic dianhydride.

7. The low water absorption coal gangue roadbed filler according to claim 1, characterized in that: In step A1, the mixed solution is spread on the substrate and irradiated with ultraviolet light. The specific operation method is as follows: the mixed solution is cast on the glass plate, and the casting thickness is controlled to 80-150nm with a scraper. Then, the solution is irradiated with a wavelength of 365nm and an intensity of 25-50mW / cm 2 UV irradiation for 0.5h is sufficient.

8. The low water absorption coal gangue roadbed filler according to claim 1, characterized in that: In step A2, the mass fraction of perfluoroalkyl propylene oxide in the fluorinated liquid is 5-10 wt %, and the mass fraction of boric acid in the fluorinated liquid is 0.3 wt %.

9. The low water absorption coal gangue roadbed filler according to claim 1, characterized in that: In step A2, the specific operation of the heat treatment is: first heating at 120°C for 10 minutes, then cooling to 80°C and keeping warm for 20 minutes.

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