A subgrade soil-cement binder and its usage method

Abstract

The present invention relates to the technical field of cement-based soil solidifying agents, and specifically discloses a roadbed soil cementitious material solidifying agent and a using method thereof. The solidifying agent comprises: Portland cement, coal gangue fine particles, fly ash, silica fume, an impermeability enhancing agent, a water reducing agent and fibers. The impermeability enhancing agent is prepared by the following method: (1) Dispersing polyaluminum sulfate powder into absolute ethanol, then adding a silane coupling agent and a water repellent and heating and insulating under stirring conditions. After completion, the solid matter is separated out to obtain modified polyaluminum sulfate. (2) Adding the modified polyaluminum sulfate to water and heating and insulating under stirring conditions. After completion, the water is evaporated to remove the water, and the obtained solid product is ground. The solidifying agent of the present invention not only reduces the adverse effect of acidic soil on the stability of the formed soil solidified body, but also improves the impermeability and the durability of the soil solidified body.

Description

Technical Field

[0001] The present invention relates to the technical field of cement-based soil solidifying agents, and particularly relates to a roadbed soil cementitious material solidifying agent and a using method thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to increase the understanding of the overall background of the present invention, and is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] The reinforcement treatment of roadbeds is a very important link in engineering construction, especially for roadbed projects such as highways and railways that need to be built on soft soil layers. One of the currently adopted methods is the soil solidification technology, that is, a solidifying agent is incorporated into the soil, and the strength and bearing capacity of the soil layer are improved by the cementing and solidifying action of the solidifying agent. The silicate cement-based material is one of the commonly used soil solidifying agents. After being incorporated into the soil, the cementitious components formed by reacting with water can achieve the rapid cementing and hardening of loose soil.

[0004] However, for acidic soils, when using cement-based materials for solidification, the hydration products of cement are easily eroded and damaged, resulting in the instability of the soil solidified body and a decrease in strength. This is because the hydration products of traditional silicate cement-based materials in the soil contain a large amount of calcium hydroxide, which has poor acid resistance. When encountering acidic soil, it is easily eroded and dissolved, and gradually loses after forming soluble substances, resulting in an increase in the porosity of the soil solidified body, a decrease in strength, and a reduction in stability. In addition, the soil solidified body formed by using traditional silicate cement-based materials also has the problem of insufficient impermeability and is prone to leakage during service, affecting the stability of the roadbed. Summary of the Invention

[0005] In view of the above problems, the present invention discloses a roadbed soil cementitious material solidifying agent and a using method thereof, which not only reduce the adverse effects of acidic soil on the stability of the formed soil solidified body, but also improve the impermeability, thereby being beneficial to improving the durability of the soil solidified body. Specifically, the technical solution of the present invention is as follows.

[0006] First of all, the present invention discloses a roadbed soil cementitious material solidifying agent, which comprises the following components: 200-275 parts by weight of portland cement, 130-160 parts by weight of coal gangue fine particles, 280-400 parts by weight of fly ash, 100-142 parts by weight of silica fume, 60-78 parts by weight of impermeability enhancer, 3-6.5 parts by weight of water reducing agent, and 25-40 parts by weight of fiber. The impermeability enhancer is prepared by the following method:

[0007] (1) Disperse the polyaluminum sulfate powder into absolute ethanol, then add a silane coupling agent and a water repellent, and heat and keep warm under stirring conditions. After completion, separate the solid matter to obtain the modified polyaluminum sulfate.

[0008] (2) Add the modified polyaluminum sulfate to water and heat and keep warm under stirring conditions. After completion, evaporate to dryness to remove the water, and the anti-seepage enhancer is obtained.

[0009] Further, in step (1), the ratio of the polyaluminum sulfate powder to absolute ethanol is 1 g: 20 - 30 ml. Optionally, the fineness of the polyaluminum sulfate powder is 100 - 200 mesh.

[0010] Further, in step (1), the silane coupling agent is 0.15 - 0.3% of the mass of the polyaluminum sulfate powder. Optionally, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, etc.

[0011] Further, in step (1), the water repellent is 0.5 - 0.8% of the mass of the polyaluminum sulfate powder. Optionally, the water repellent includes at least one of tridecafluorooctyltrimethoxysilane, perfluorooctyltriethoxysilane, perfluoroalkylsiloxane, heptadecafluorodecyltriethoxysilane, hexamethyldisilazane, etc.

[0012] Further, in step (1), the heating temperature is 60 - 70 °C, and the heat preservation time is 1 - 1.5 hours.

[0013] Further, in step (2), the ratio of the modified polyaluminum sulfate to water is 1 g: 5 - 10 ml.

[0014] Further, in step (2), the heating temperature is 40 - 60 °C, and the heat preservation time is 10 - 20 min.

[0015] Further, in step (2), the evaporation temperature is 80 - 100 °C, and evaporate to dryness at this temperature until the weight of the remaining solid product no longer changes.

[0016] Further, the coal gangue particles are treated by the following method: Calcinate the granular coal gangue, and after completion, immerse it in a sodium silicate solution, then separate the solid particles and dry them to obtain the product.

[0017] Further, the calcination temperature is 700 - 850 °C, and the time is 30 - 45 min.

[0018] Furthermore, the ratio of the granular coal gangue to the sodium silicate solution is 1 g: 5 - 20 ml. Optionally, the mass fraction of the sodium silicate solution is 4 - 10%.

[0019] Furthermore, the impregnation time is 1 - 2 hours. Optionally, the particle size distribution of the coal gangue microparticles is between 1 - 5 mm.

[0020] Furthermore, the fibers include at least one of polyethylene fibers, polypropylene fibers, polyvinyl alcohol fibers, polyacrylonitrile fibers, etc. Optionally, the length of the fibers is 10 - 25 mm. These fibers help to further improve the strength and stability of the soil solidified body.

[0021] Furthermore, the water reducing agent includes at least one of polycarboxylate water reducing agent, naphthalene series water reducing agent, lignosulfonate water reducing agent, etc.

[0022] Secondly, the present invention discloses a method for using the roadbed soil cementitious material curing agent, which includes the following steps: mixing the dry acidic soil to be solidified with the curing agent evenly, and then adding water and mixing evenly.

[0023] Furthermore, the dosage of the curing agent is 20 - 30% of the mass of the soil to be solidified. The water is 42 - 48% of the total mass of the soil to be solidified and the curing agent. Optionally, the pH of the soil to be solidified is 5 - 6.5.

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

[0025] When using ordinary Portland cement to solidify acidic subgrade soil, there are problems such as a decrease in the strength of the consolidated body, a reduction in stability, and insufficient impermeability of the consolidated body. The present invention effectively overcomes the above problems by adding an impermeability enhancer to the curing agent. To this end, the present invention first grafts a hydrophobic agent onto polyaluminum sulfate to form modified polyaluminum sulfate, and then adds it to water for hydrolysis reaction. The hydrophobic agent is coated therein by the cementing action of the formed aluminum hydroxide colloid to form an impermeability enhancer. After adding it to the soil curing agent, since the coating of the hydrophobic agent by aluminum hydroxide effectively reduces the influence on the hydration of Portland cement particles, the surface of the cement particles can be in full contact with the mixing water, thereby ensuring the full progress of the hydration reaction, forming more cementitious components, and improving the strength of the soil consolidated body. In addition, the aluminum hydroxide in the impermeability enhancer can also neutralize the hydrogen ions in the acidic soil and reduce the soil acidity. The initiation of the hydration reaction of cement requires a certain amount of time, which helps to prevent the problems of a decrease in the strength and stability of the soil consolidated body caused by the dissolution of calcium hydroxide, the hydration product of cement, by hydrogen ions in the acidic soil. At the same time, the hydrophobic agent is gradually released by the reaction of aluminum hydroxide with hydrogen ions in the impermeability enhancer. Since the surface of the cement particles has been in full contact with water at this time, the released hydrophobic agent can not only construct a hydrophobic system in the soil consolidated body to improve the waterproof and impermeability ability of the soil consolidated body, but also avoid the influence on cement hydration. Again, the aluminum ions formed after the reaction of aluminum hydroxide with hydrogen ions in the impermeability enhancer react with the calcium hydroxide solution, the hydration product of the subsequent hydration reaction, to re-form aluminum hydroxide, which fills the pores of the soil consolidated body and does not dissolve and flow away in water. This not only improves the density of the consolidated body, thereby improving the waterproof and impermeability ability, but also helps to improve the strength of the consolidated body.

[0026] In addition, in the present invention, the coal gangue aggregate in the curing agent is first calcined and then activated with a sodium silicate solution. This not only eliminates its adverse effects on the structural stability of the soil solidified body, but also can reduce the soil acidity and improve the strength of the solidified body by participating in the hydration reaction itself. This is because the organic matter contained in the coal gangue aggregate is removed after high-temperature calcination, avoiding volume changes caused by the reaction of the organic matter in the coal gangue aggregate during the service process of the soil solidified body and affecting the structural stability of the solidified body. At the same time, through the treatment with the sodium silicate solution, the reaction activity of the coal gangue can be effectively improved. It can carry out pozzolanic reactions with calcium hydroxide generated by the cement hydration reaction to form cementitious components such as calcium silicate hydrate and calcium aluminate hydrate, increasing the content of cementitious components in the soil solidified body and thus improving the strength of the solidified body. In addition, the sodium silicate stored in the pores formed after the coal gangue aggregate removes the organic matter can react with hydrogen ions in the soil to form silicic acid, and the silicic acid neutralizes with the calcium hydroxide solution generated by the subsequent cement hydration to form calcium silicate precipitation, which fills the pores of the coal gangue and can play a densifying role, helping to improve the strength and impermeability of the coal gangue aggregate. In addition, the utilization and consumption of the hydration product calcium hydroxide in the above process also contribute to promoting the degree of cement hydration reaction and improving the strength of the soil solidified body. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The attached drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings, where:

[0028] Figure 1 Diagram of the anti-seepage enhancer sample prepared for Example 1 below.

[0029] Figure 2 Diagram of the compressive strength test of the solidified soil specimen prepared for Example 1 below.

[0030] Figure 3 Diagram of the anti-seepage performance test for Examples 1 to 6 below.

[0031] Figure 4 Diagram of the contact angle test of the solidified soil specimen for Example 1 below.

[0032] Figure 5 Diagram of the compressive strength test of the solidified soil specimen prepared for Example 2 below.

[0033] Figure 6 Diagram of the contact angle test of the solidified soil specimen for Example 2 below.

[0034] Figure 7 Diagram of the compressive strength test of the solidified soil specimen prepared for Example 3 below.

[0035] Figure 8 Compressive strength test diagram of the solidified soil specimens prepared for Example 4 below.

[0036] Figure 9 Compressive strength test diagram of the solidified soil specimens prepared for Example 5 below.

[0037] Figure 10 Compressive strength test diagram of the solidified soil specimens prepared for Example 6 below.

[0038] Figure 11 Compressive strength test diagram of the solidified soil specimens prepared for Example 7 below.

[0039] Figure 12 Anti-seepage performance test diagram of Example 7 and Example 8 below.

[0040] Figure 13 Compressive strength test diagram of the solidified soil specimens prepared for Example 8 below. Detailed implementation mode

[0041] The present invention will be further elaborated below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. The experimental methods without specific conditions noted in the following embodiments are generally carried out according to conventional conditions or according to the conditions recommended by the manufacturer.

[0042] Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be obtained through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in the conventional manner in the art or according to the product instructions. In addition, any methods and materials similar or equivalent to the described content can be applied to the method of the present invention.

[0043] Example 1:

[0044] The preparation of a solidifying agent for subgrade soil cementitious materials includes the following steps:

[0045] (1) Add polyaluminum sulfate powder with a fineness of 180 meshes to anhydrous ethanol at a ratio of 1 g: 25 ml. After stirring evenly, add γ-aminopropyltriethoxysilane and tridecafluorooctyltrimethoxysilane, wherein: the γ-aminopropyltriethoxysilane is 0.22% of the mass of the polyaluminum sulfate powder, and the tridecafluorooctyltrimethoxysilane is 0.6% of the mass of the polyaluminum sulfate powder. Then heat to 70 °C under continuous stirring and keep warm for 1 hour. After completion, filter out the solid matter to obtain modified polyaluminum sulfate.

[0046] (2) Add the modified polyaluminum sulfate to water at a ratio of 1 g: 8 ml, then heat it to 50 °C under continuous stirring and keep it warm for 10 min. After completion, continue to heat it to 100 °C for evaporation to dryness until the weight of the remaining solid product no longer changes, thus obtaining the anti-seepage enhancer (as Figure 1 shown), and set it aside for later use.

[0047] (3) First, calcine the crushed granular gangue at 800 °C for 35 min. After completion, cool it to room temperature. Mix the calcined product with a sodium silicate solution with a mass fraction of 7% at a ratio of 1 g: 10 ml, stir evenly, and then impregnate for 1.5 hours. After completion, filter out the particulate matter and dry it at 100 °C until the weight no longer changes to obtain gangue microparticles with a particle size distribution between 2 and 5 mm, and set it aside for later use.

[0048] (4) Weigh each component according to the following ratio: 237 parts by weight of 42.5 ordinary Portland cement, 145 parts by weight of the gangue microparticles of this example, 300 parts by weight of fly ash, 120 parts by weight of silica fume, 65 parts by weight of the anti-seepage enhancer of this example, 4 parts by weight of polycarboxylate superplasticizer, and 28 parts by weight of polypropylene fiber with a length of 25 mm. Mix the above components evenly by stirring to obtain the cementitious material curing agent.

[0049] Incorporate 25% of the mass of the cementitious material curing agent of this example into the dry soil to be cured (pH = 5.87). After stirring for 3 min, add 45% of the mass of water of the obtained mixed powder, and then continue to stir for 2 min. Pour the obtained solidified soil into a mold, and after hardening and demolding, cure it naturally for 28 d to obtain solidified soil specimens. Then test the compressive strength (as Figure 2 shown) and anti-seepage performance (as Figure 3 shown) of the solidified soil specimens. In addition, test the contact angle (as Figure 4 shown) of the solidified soil specimens. The larger the contact angle, the better the hydrophobic anti-seepage performance. The test results are shown in the following table:

[0050] .

[0051] Example 2:

[0052] Preparation of a subgrade soil cementitious material curing agent, including the following steps:

[0053] (1) Add the polyaluminum sulfate powder with a fineness of 200 mesh to absolute ethanol at a ratio of 1 g: 30 ml. After stirring evenly, add γ-methacryloxypropyltrimethoxysilane and perfluoroalkyl polysiloxane, where: the γ-methacryloxypropyltrimethoxysilane is 0.15% of the mass of the polyaluminum sulfate powder, and the perfluoroalkyl polysiloxane is 0.5% of the mass of the polyaluminum sulfate powder. Then heat to 60 °C and keep warm for 1 hour under continuous stirring. After completion, filter out the solid matter to obtain modified polyaluminum sulfate.

[0054] (2) Add the modified polyaluminum sulfate to water at a ratio of 1 g: 10 ml, then heat to 40 °C and keep warm for 20 min under continuous stirring. After completion, continue to heat to 90 °C for evaporation to dryness until the weight of the remaining solid product no longer changes, and the anti-seepage enhancer is obtained and reserved.

[0055] (3) First, calcine the crushed granular coal gangue at 700 °C for 45 min. After completion, cool to room temperature. Mix the calcined product with a 4% sodium silicate solution at a ratio of 1 g: 20 ml and stir evenly, then impregnate for 2 hours. After completion, filter out the particulate matter and dry it at 100 °C until the weight no longer changes to obtain coal gangue fine particles with a particle size distribution between 1 and 3 mm and reserve them.

[0056] (4) Weigh each component according to the following ratio: 275 parts by weight of 42.5 ordinary Portland cement, 160 parts by weight of the coal gangue fine particles of this example, 400 parts by weight of fly ash, 142 parts by weight of silica fume, 78 parts by weight of the anti-seepage enhancer of this example, 6.5 parts by weight of naphthalene-based water reducer, and 40 parts by weight of polyvinyl alcohol fiber with a length of 10 mm. Mix the above components and stir evenly to obtain the cementitious material curing agent.

[0057] Incorporate 30% of the mass of the cementitious material curing agent of this example into the dry acidic soil to be cured (pH = 5.03), stir for 3 min, then add 48% of the water of the mass of the obtained mixed powder, and then continue to stir for 2 min. Pour the obtained solidified soil into a mold, cure and demold it, and then naturally cure it for 28 d to obtain solidified soil specimens. Then test the compressive strength (as Figure 5 shown) and anti-seepage performance (as Figure 3 shown) of the solidified soil specimens. In addition, test the contact angle (as Figure 6 shown) of the solidified soil specimens, and the test results are shown in the following table:

[0058] .

[0059] Example 3:

[0060] Preparation of a subgrade soil cementitious material curing agent, including the following steps:

[0061] (1) Add aluminum poly sulfate powder with a fineness of 100 mesh to absolute ethanol at a ratio of 1 g:20 ml. After stirring evenly, add γ-glycidoxypropyltrimethoxysilane and heptadecafluorodecyltriethoxysilane. Among them, the γ-glycidoxypropyltrimethoxysilane is 0.3% of the mass of the aluminum poly sulfate powder, and the heptadecafluorodecyltriethoxysilane is 0.8% of the mass of the aluminum poly sulfate powder. Then heat to 60 °C under continuous stirring and keep warm for 1.5 hours. After completion, filter out the solid matter to obtain modified aluminum poly sulfate.

[0062] (2) Add the modified aluminum poly sulfate to water at a ratio of 1 g:5 ml, then heat to 60 °C under continuous stirring and keep warm for 12 min. After completion, continue to heat to 80 °C for evaporation to dryness until the weight of the remaining solid product no longer changes, and then the anti-seepage enhancer is obtained and set aside.

[0063] (3) First, calcine the crushed granular coal gangue at 850 °C for 30 min. After completion, cool to room temperature. Mix the calcined product with a 10% sodium silicate solution by weight at a ratio of 1 g:5 ml, stir evenly, and then soak for 1 hour. After completion, filter out the particulate matter and dry it at 100 °C until the weight no longer changes to obtain coal gangue microparticles with a particle size distribution between 1 and 5 mm, and set aside.

[0064] (4) Weigh each component according to the following ratio: 200 parts by weight of 42.5 ordinary Portland cement, 130 parts by weight of the coal gangue microparticles of this example, 280 parts by weight of fly ash, 100 parts by weight of silica fume, 60 parts by weight of the anti-seepage enhancer of this example, 3 parts by weight of lignosulfonate water reducer, and 25 parts by weight of polyethylene fiber with a length of 20 mm. Mix the above components evenly by stirring to obtain a cementitious material curing agent.

[0065] Incorporate 20% of the mass of the cementitious material curing agent of this example into the dry acidic soil to be cured (pH = 6.51), stir for 3 min, then add 42% of the water of the mass of the obtained mixed powder, and then continue to stir for 2 min. Pour the obtained solidified soil into a mold, and after hardening and demolding, cure it naturally for 28 d to obtain a solidified soil specimen. Then test the compressive strength (as Figure 7 shown) and anti-seepage performance (as Figure 3 shown) of the solidified soil specimen. In addition, test the contact angle of the solidified soil specimen, and the test results are shown in the following table:

[0066] .

[0067] Example 4:

[0068] Preparation of a solidifying agent for subgrade soil cementitious material, comprising the following steps:

[0069] (1) Add polyaluminum sulfate powder with a fineness of 180 meshes to absolute ethanol at a ratio of 1 g: 25 ml, stir evenly, and then add γ-aminopropyltriethoxysilane accounting for 0.22% of the mass of the polyaluminum sulfate powder. Then heat to 70 °C under continuous stirring and keep warm for 1 hour. After completion, filter out the solid matter to obtain modified polyaluminum sulfate.

[0070] (2) Add the modified polyaluminum sulfate to water at a ratio of 1 g: 8 ml, then heat to 50 °C under continuous stirring and keep warm for 10 min. After completion, continue to heat to 100 °C for evaporation to dryness until the weight of the remaining solid product no longer changes, thereby obtaining an anti-seepage enhancer for standby.

[0071] (3) Weigh each component according to the following ratio: 237 parts by weight of 42.5 ordinary Portland cement, 145 parts by weight of the coal gangue particles in the above Example 1, 300 parts by weight of fly ash, 120 parts by weight of silica fume, 65 parts by weight of the anti-seepage enhancer in this example, 4 parts by weight of polycarboxylate water reducer, and 28 parts by weight of polypropylene fiber with a length of 25 mm. Mix the above components and stir evenly to obtain the cementitious material solidifying agent.

[0072] Incorporate 25% of the cementitious material solidifying agent in this example by its mass into dry soil to be solidified (pH = 5.87), stir for 3 min, then add water accounting for 45% of the mass of the obtained mixed powder, and then continue to stir for 2 min. Pour the obtained solidified soil into a mold, and after hardening and demolding, cure it naturally for 28 d to obtain a solidified soil specimen. Then test the compressive strength (as Figure 8 shown) and anti-seepage performance (as Figure 3 shown) of the solidified soil specimen. In addition, test the contact angle of the solidified soil specimen, and the test results are shown in the following table:

[0073] .

[0074] Example 5:

[0075] Preparation of a solidifying agent for subgrade soil cementitious material, comprising the following steps:

[0076] (1) Screen the crushed granular coal gangue to obtain coal gangue particles with a particle size distribution between 2 - 5 mm for standby.

[0077] (2) Weigh each component according to the following proportions: 237 parts by weight of 42.5 ordinary Portland cement, 145 parts by weight of the coal gangue particles of this embodiment, 300 parts by weight of fly ash, 120 parts by weight of silica fume, 65 parts by weight of the anti-seepage enhancer of the above-mentioned Example 1, 4 parts by weight of polycarboxylate water reducer, and 28 parts by weight of polypropylene fibers with a length of 25 mm. Mix the above components and stir evenly to obtain the cementitious material curing agent.

[0078] Incorporate 25% of the mass of the cementitious material curing agent of this embodiment into the dry soil to be cured (pH = 5.87), stir for 3 min, then add 45% of the water of the mass of the obtained mixed powder, and then continue to stir for 2 min. Pour the obtained solidified soil into a mold, and after hardening and demolding, cure it naturally for 28 d to obtain solidified soil specimens. Then test the compressive strength (as Figure 9 shown) and anti-seepage performance (as Figure 3 shown) of the solidified soil specimens. In addition, test the contact angle of the solidified soil specimens. The larger the contact angle, the better the hydrophobic anti-seepage performance. The test results are shown in the following table:

[0079] .

[0080] Example 6:

[0081] Preparation of a subgrade soil cementitious material curing agent, including the following steps:

[0082] (1) Add polyaluminum sulfate powder with a fineness of 100 mesh to absolute ethanol at a ratio of 1 g:20 ml, stir evenly, and then add γ-glycidoxypropyltrimethoxysilane and heptadecafluorodecyltriethoxysilane, where: the γ-glycidoxypropyltrimethoxysilane is 0.3% of the mass of the polyaluminum sulfate powder, and the heptadecafluorodecyltriethoxysilane is 0.8% of the mass of the polyaluminum sulfate powder. Then heat to 60 °C and keep warm for 1.5 hours under continuous stirring. After completion, filter out the solid matter, dry it to obtain the anti-seepage enhancer, and set it aside.

[0083] (2) Weigh each component according to the following proportions: 200 parts by weight of 42.5 ordinary Portland cement, 130 parts by weight of the coal gangue particles of the above-mentioned Example 3, 280 parts by weight of fly ash, 100 parts by weight of silica fume, 60 parts by weight of the anti-seepage enhancer of this embodiment, 3 parts by weight of lignosulfonate water reducer, and 25 parts by weight of polyethylene fibers with a length of 20 mm. Mix the above components and stir evenly to obtain the cementitious material curing agent.

[0084] In the dry acidic soil to be solidified (pH = 6.51), 20% of the mass of the cementitious material curing agent of this embodiment is incorporated, stirred for 3 min, then 42% of the mass of the water of the obtained mixed powder is added, and then stirred for another 2 min. The obtained solidified soil is poured into a mold, and after hardening and demolding, it is naturally cured for 28 d to obtain a solidified soil specimen. Then, the compressive strength of the solidified soil specimen (as shown in Figure 10 ), and the water permeability resistance (as shown in Figure 3 ) are tested. In addition, the contact angle of the solidified soil specimen is tested, and the test results are shown in the following table:

[0085] .

[0086] Example 7:

[0087] Preparation of a cementitious material curing agent for subgrade soil includes the following steps:

[0088] (1) The crushed granular coal gangue is first calcined at 700 °C for 45 min, and after completion, it is cooled to room temperature. The calcined product is mixed with clear water at a ratio of 1 g:20 ml and stirred evenly, and then impregnated for 2 hours. After completion, the particulate matter is filtered out and dried at 100 °C until the weight no longer changes to obtain coal gangue microparticles with a particle size distribution between 1 and 3 mm, which are reserved for use.

[0089] (2) Weigh each component according to the following ratio: 275 parts by weight of 42.5 ordinary Portland cement, 160 parts by weight of the coal gangue microparticles of this embodiment, 400 parts by weight of fly ash, 142 parts by weight of silica fume, 78 parts by weight of the anti-seepage enhancer of the above Example 2, 6.5 parts by weight of naphthalene-based water reducer, and 40 parts by weight of polyvinyl alcohol fibers with a length of 10 mm. Mix the above components and stir evenly to obtain the cementitious material curing agent.

[0090] In the dry acidic soil to be solidified (pH = 5.03), 30% of the mass of the cementitious material curing agent of this embodiment is incorporated, stirred for 3 min, then 48% of the mass of the water of the obtained mixed powder is added, and then stirred for another 2 min. The obtained solidified soil is poured into a mold, and after hardening and demolding, it is naturally cured for 28 d to obtain a solidified soil specimen. Then, the compressive strength of the solidified soil specimen (as shown in Figure 11 ), and the water permeability resistance (as shown in Figure 12 ) are tested. In addition, the contact angle of the solidified soil specimen is tested, and the test results are shown in the following table:

[0091] .

[0092] Example 8:

[0093] Preparation of a cementitious material curing agent for subgrade soil includes the following steps:

[0094] Weigh each component according to the following ratio: 200 parts by weight of 42.5 ordinary portland cement, 130 parts by weight of the coal gangue particles in Example 3 above, 280 parts by weight of fly ash, 100 parts by weight of silica fume, 3 parts by weight of lignosulfonate water reducer, and 25 parts by weight of polyethylene fibers with a length of 20 mm. Mix the above components and stir evenly to obtain the cementitious material curing agent.

[0095] In the dry acidic soil to be solidified (pH = 6.51), incorporate 20% of the mass of the cementitious material curing agent of this example, stir for 3 min, then add 42% of the water of the mass of the obtained mixed powder, and then continue to stir for 2 min. Pour the obtained solidified soil into a mold, and after hardening and demolding, cure it naturally for 28 d to obtain a solidified soil specimen. Then test the compressive strength (as Figure 13 shown) and the water permeability resistance (as Figure 12 shown) of the solidified soil specimen. In addition, test the contact angle of the solidified soil specimen, and the test results are shown in the following table:

[0096] .

[0097] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still repair the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any repair, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A solidifying agent for subgrade soil-cement binder, characterized in that, It comprises the following components: 200 - 275 parts by weight of portland cement, 130 - 160 parts by weight of coal gangue fine particles, 280 - 400 parts by weight of fly ash, 100 - 142 parts by weight of silica fume, 60 - 78 parts by weight of impermeability enhancer, 3 - 6.5 parts by weight of water reducer, and 25 - 40 parts by weight of fiber; wherein: The impermeability enhancer is prepared by the following method: (1) Disperse the polyaluminum sulfate powder into absolute ethanol, then add a silane coupling agent and a water repellent, and heat to 60 - 70 °C under stirring conditions for heat preservation for 1 - 1.5 hours; after completion, separate the solid matter to obtain modified polyaluminum sulfate; the water repellent is 0.5 - 0.8% of the mass of the polyaluminum sulfate powder; the water repellent includes at least one of: tridecafluorooctyltrimethoxysilane, perfluorooctyltriethoxysilane, polyperfluoroalkylsiloxane, heptadecafluorodecyltriethoxysilane, hexamethyldisilazane; (2) Add the modified polyaluminum sulfate to water and heat for heat preservation under stirring conditions, and after completion, evaporate to dryness to remove the water to obtain the impermeability enhancer.

2. The roadbed soil cementitious material curing agent according to claim 1, characterized in that, In step (1), the ratio of the polyaluminum sulfate powder to absolute ethanol is 1 g: 20 - 30 ml.

3. The roadbed soil-cement binder according to claim 1, characterized in that, In step (1), the fineness of the polyaluminum sulfate powder is 100 - 200 mesh.

4. The subgrade soil-cement binder according to claim 1, wherein In step (1), the silane coupling agent is 0.15 - 0.3% of the mass of the polyaluminum sulfate powder.

5. The roadbed soil-cement binder according to claim 1, characterized in that, In step (1), the silane coupling agent includes at least one of: γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane.

6. The subgrade soil-cement binder according to claim 1, characterized in that, In step (2), the ratio of the modified polyaluminum sulfate to water is 1 g: 5 - 10 ml.

7. The roadbed soil-cement binder according to claim 1, characterized in that, In step (2), the heating temperature is 40 - 60 °C, and the heat preservation time is 10 - 20 min.

8. The roadbed soil-cement binder according to claim 1, wherein In step (2), the evaporation temperature is 80 - 100 °C, and evaporate to dryness at this temperature until the weight of the remaining solid product no longer changes.

9. The subgrade soil-cement binder according to claim 1, characterized in that, The coal gangue fine particles are processed by the following method: Calcinate the granular coal gangue, and after completion, immerse it in a sodium silicate solution, and then separate the solid particulate matter and dry it to obtain.

10. The roadbed soil-cement binder according to claim 9, characterized in that, The calcination temperature is 700 - 850 °C, and the time is 30 - 45 min.

11. The roadbed soil-cement binder according to claim 9, characterized in that, The ratio of the granular coal gangue to the sodium silicate solution is 1 g: 5 - 20 ml.

12. The roadbed soil-cement binder according to claim 9, characterized in that, The mass fraction of the sodium silicate solution is 4 - 10%.

13. The roadbed soil-cement binder according to claim 9, characterized in that, The immersion time is 1 - 2 hours.

14. The roadbed soil-cement binder according to claim 9, characterized in that, The particle size of the coal gangue fine particles is distributed between 1 - 5 mm.

15. The subgrade soil-cement binder according to any one of claims 1-14, characterized in that, The fiber includes at least one of: polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, polyacrylonitrile fiber.

16. The roadbed soil cementitious material curing agent according to any one of claims 1-14, characterized in that, The length of the fiber is 10 - 25 mm.

17. The subgrade soil-cement binder according to any one of claims 1-14, characterized in that, The water reducer includes at least one of: polycarboxylate water reducer, naphthalene series water reducer, lignosulfonate water reducer.

18. The method for using the subgrade soil-cement cementitious material curing agent according to any one of claims 1-17, characterized in that, It includes the following steps: Mix the dry acidic soil to be solidified evenly with the curing agent, and then add water and mix evenly.

19. The method of use according to claim 18, wherein The dosage of the curing agent is 20 - 30% of the mass of the soil to be solidified.

20. The usage method according to claim 18, wherein, The water is 42 - 48% of the total mass of the soil to be solidified and the curing agent.

21. The usage method according to claim 18, wherein The pH of the soil to be solidified is 5 - 6.5.

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