A subgrade soil stabilizer, a preparation method thereof, and a subgrade material containing the same

Abstract

The application discloses a kind of roadbed soil solidifying agent and preparation method thereof, and the roadbed material comprising it, belong to soil solidifying agent technical field.The solidifying agent includes following weight fraction of each component: bentonite 40~50 parts, hexadecyl trimethyl ammonium chloride 0.5~2.5 parts, silicon dioxide 40~50 parts, alumina 20~30 parts, nano calcium carbonate 6~10 parts, ion complexing agent 1~3 parts, silane coupling agent 10~20 parts.Silicon dioxide, alumina and hexadecyl trimethyl ammonium chloride can significantly improve the ability of bentonite to release soil particle surface adsorbed water, and then significantly improve the water stability and strength of roadbed material.The solidifying agent of the application can reduce the adsorbed water in soil under the interaction of each component, and optimize the cement hydration performance, tightly cement soil particles together, and synergistically enhance the water stability and strength of solidified soil.

Description

Technical Field

[0001] This invention belongs to the field of soil stabilizer technology, specifically relating to a roadbed soil stabilizer and its preparation method, as well as roadbed materials containing the stabilizer. Background Technology

[0002] With the rapid development of highway infrastructure, the total demand for sand and gravel aggregates in highway construction is constantly increasing. However, the long-term indiscriminate mining of sand and gravel aggregates has led to resource shortages, riverbed changes, landslides, and severe damage to the ecological environment. The resource depletion caused by over-exploitation of sand and gravel materials forces highway construction to seek new alternative materials to meet the material demands of engineering projects. On the other hand, the output of earthwork in road construction remains high, but the comprehensive utilization rate is less than 20% on average. Furthermore, long-term stockpiling of earthwork inevitably leads to environmental pollution, occupancy of urban space, and high transportation costs. If earthwork could be used as filler in highway subgrade construction, it would not only solve the problem of sand and gravel material shortages but also realize the resource utilization of earthwork, enabling highway construction to achieve good social, economic, and ecological benefits.

[0003] However, the high water content of subgrade soil makes it difficult to meet the requirements for compaction and unconfined compressive strength. Traditional methods, such as using large amounts of cement and lime as solidifying agents, are generally employed to solidify high-liquid-limit clay to improve its bearing capacity. However, the production process of these traditional solidifying agents directly emits large amounts of CO2 and consumes significant amounts of fossil fuels, which is detrimental to sustainable development. Therefore, selecting a suitable soil stabilizer has become an urgent task in current highway construction. A soil stabilizer is a soil hardening agent that can directly cement the surface of soil particles at room temperature or react with clay minerals in soil particles to form a cementitious substance. It is a composite material that improves and enhances the technical properties of soil, overcoming the shortcomings of single traditional materials such as lime, cement, and fly ash. It can react with various soil types to form solidified soil with certain bearing capacity, impermeability, and durability, and has broad application prospects in highway, railway, and subway construction projects. Soil treated with soil stabilizers is easier to compact and achieves a stable state, thus forming an integral structure and improving the load-bearing capacity of roads. Soil treated with soil stabilizers has significantly improved properties such as strength, density, resilient modulus, and shear strength, thereby extending the service life of roads, saving engineering maintenance costs, and having high economic and environmental benefits. It is currently an ideal choice for road construction materials.

[0004] Existing soil stabilizers have low solidification strength, resulting in low compaction of the roadbed after solidification and poor water stability of the stabilized soil. This leads to a short interval between highway completion and subsequent maintenance, high maintenance costs, and negatively impacts highway usability. Therefore, developing a more effective soil stabilizer will play a crucial role in highway construction. Summary of the Invention

[0005] In view of the shortcomings of the prior art, one of the objectives of this invention is to provide a roadbed soil solidifier. Using the solidifier of this invention can significantly reduce the amount of cement used, and the resulting solidified soil has high strength, high density, and good water stability.

[0006] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0007] A roadbed soil stabilizer comprises the following components in parts by weight: 40-50 parts bentonite, 0.5-2.5 parts hexadecyltrimethylammonium chloride, 40-50 parts silica, 20-30 parts alumina, 6-10 parts nano-calcium carbonate, 1-3 parts ion complexing agent, and 10-20 parts silane coupling agent.

[0008] In the roadbed soil solidification agent of this invention, the ion exchange capacity of bentonite is utilized to exchange cations from silica and alumina into the bentonite. Then, calcium and aluminum ions in the bentonite exchange with hydrophilic cations on the surface of soil particles, displacing hydrophilic ions from the soil. Hexadecyltrimethylammonium chloride increases the interlayer spacing of the bentonite, enhancing its ability to accommodate hydrophilic ions and releasing adsorbed water from the surface of soil particles. Simultaneously, the calcium and aluminum ions displaced from the bentonite form crystalline hydrates, consuming free water in the soil and generating a cementing substance that can bind the soil, significantly improving the water stability and strength of the solidified soil. The silane coupling agent can chemically react with the bentonite and nano-calcium carbonate in the solidification agent to enhance the binding of the solidification agent with organic matter in the soil particles; nano-calcium carbonate can optimize cement hydration and hardening structure, promote the formation of ettringite, and enhance the strength of the solidified soil. In summary, the curing agent of the present invention, through the interaction of its components, can reduce adsorbed water in the soil, optimize cement hydration performance, tightly bind soil particles together, and synergistically enhance the water stability and strength of the solidified soil.

[0009] Preferably, the roadbed soil solidifier comprises the following components in parts by weight: 45 parts bentonite, 1.5 parts hexadecyltrimethylammonium chloride, 45 parts silica, 25 parts alumina, 8 parts nano-calcium carbonate, 1.5 parts ion complexing agent, and 15 parts silane coupling agent.

[0010] Preferably, the bentonite includes at least one of calcium-based bentonite, aluminum-based bentonite, and magnesium-based bentonite.

[0011] Preferably, the average particle size of the nano-calcium carbonate is 60-80 nm.

[0012] Preferably, the ionic complexing agent includes at least one of sodium citrate, sodium gluconate, and sodium maleate.

[0013] Preferably, the silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0014] Another object of the present invention is to provide a method for preparing the aforementioned roadbed soil solidification agent, comprising the following steps:

[0015] S1. Disperse the bentonite in deionized water, then add the hexadecyltrimethylammonium chloride, stir in a water bath at 60-70°C for 1-2 hours, let stand for 10-14 hours, and dry to obtain modified bentonite;

[0016] S2. Add sodium hydroxide solution to a container, heat to 50-65°C, add silicon dioxide and aluminum oxide, stir for 3-4 hours under a protective gas atmosphere, then add the modified bentonite obtained in step S1, stir for 4-6 hours, age for 1-2 hours, and dry to obtain powder.

[0017] S3. Mix the powder obtained in step S2 with the nano-calcium carbonate, ion complexing agent, and silane coupling agent evenly to obtain the roadbed soil solidifying agent.

[0018] Another object of the present invention is to provide a roadbed material comprising the following components in parts by weight per 100 parts by weight of soil: 2-4 parts of curing agent, 8-10 parts of cement, 15-25 parts of crushed stone, and 10-20 parts of water.

[0019] Preferably, each 100 parts by weight of soil includes the following components in parts by weight: 3 parts of curing agent, 9 parts of cement, 20 parts of crushed stone, and 15 parts of water.

[0020] Compared with the prior art, the advantages of the present invention are:

[0021] The silica, alumina, and hexadecyltrimethylammonium chloride of the present invention can significantly enhance the ability of bentonite to release water adsorbed on the surface of soil particles, thereby significantly improving the water stability and strength of roadbed materials.

[0022] The curing agent of the present invention, through the interaction of its components, can reduce the adsorbed water in the soil and optimize the cement hydration performance, tightly bind soil particles together, and synergistically enhance the water stability and strength of the solidified soil. Attached Figure Description

[0023] Figure 1 SEM images of the roadbed material using the curing agent of Example 1;

[0024] Figure 2 The 7-day unconfined compressive strength curves of the roadbed materials used in the examples and comparative examples are shown. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The roadbed soil solidifier of the present invention comprises the following components in parts by weight: 40-50 parts bentonite, 0.5-2.5 parts hexadecyltrimethylammonium chloride, 40-50 parts silica, 20-30 parts alumina, 6-10 parts nano calcium carbonate, 1-3 parts ion complexing agent, and 10-20 parts silane coupling agent.

[0027] As an optional embodiment, the bentonite may be selected from at least one of calcium-based bentonite, aluminum-based bentonite, and magnesium-based bentonite. The bentonite includes at least one of calcium-based bentonite, aluminum-based bentonite, and magnesium-based bentonite; the ionic complexing agent includes at least one of sodium citrate, sodium gluconate, and sodium maleate. The silane coupling agent includes at least one of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and vinyltrimethoxysilane.

[0028] The preparation method of the roadbed soil stabilizer of the present invention includes the following steps:

[0029] S1. Disperse the bentonite in deionized water, then add the hexadecyltrimethylammonium chloride, stir in a water bath at 60-70°C for 1-2 hours, let stand for 10-14 hours, and dry to obtain modified bentonite;

[0030] S2. Add sodium hydroxide solution to a container, heat to 50-65°C, add silicon dioxide and aluminum oxide, stir for 3-4 hours under a protective gas atmosphere, then add the modified bentonite obtained in step S1, stir for 4-6 hours, age for 1-2 hours, and dry to obtain powder.

[0031] S3. Mix the powder obtained in step S2 with the nano-calcium carbonate, ion complexing agent, and silane coupling agent evenly to obtain the roadbed soil solidifying agent.

[0032] In the following examples, ordinary Portland cement was used; the soil used in the examples was backfill soil from a construction site in Sujiatun, Shenyang.

[0033] Example 1

[0034] This embodiment provides a roadbed soil solidifier, comprising the following components in parts by weight: 45 parts calcium-based bentonite, 1.5 parts hexadecyltrimethylammonium chloride, 45 parts silica, 25 parts alumina, 8 parts nano-calcium carbonate, 1.5 parts sodium citrate, and 15 parts γ-aminopropyltriethoxysilane.

[0035] The preparation method of the subgrade soil stabilizer in this embodiment includes the following steps:

[0036] S1. Calcium-based bentonite was dispersed in deionized water at a weight ratio of 1:10, then hexadecyltrimethylammonium chloride was added, and the mixture was stirred in a water bath at 65°C for 2 hours, allowed to stand for 12 hours, and dried to obtain modified bentonite.

[0037] S2. Add an 8% sodium hydroxide solution to the reactor, heat to 55°C, and then add silica and alumina (the weight ratio of sodium hydroxide solution to the total weight of silica and alumina is 2:1). Stir for 3.5 hours under a nitrogen atmosphere, then add the modified bentonite obtained in step S1, stir for 5 hours, age for 1.5 hours, and dry to obtain powder.

[0038] S3. Mix the powder obtained in step S2 with nano-calcium carbonate, sodium citrate, and γ-aminopropyltriethoxysilane to obtain a roadbed soil solidifier.

[0039] Example 2

[0040] This embodiment provides a roadbed soil solidifier, comprising the following components in parts by weight: 40 parts calcium-based bentonite, 2.5 parts hexadecyltrimethylammonium chloride, 40 parts silica, 30 parts alumina, 10 parts nano-calcium carbonate, 3 parts sodium gluconate, and 10 parts γ-aminopropyltrimethoxysilane.

[0041] The preparation method of the subgrade soil stabilizer in this embodiment includes the following steps:

[0042] S1. Calcium-based bentonite was dispersed in deionized water at a weight ratio of 1:10, then hexadecyltrimethylammonium chloride was added, and the mixture was stirred in a water bath at 70°C for 1 hour, allowed to stand for 10 hours, and dried to obtain modified bentonite.

[0043] S2. Add an 8% sodium hydroxide solution to the reactor, heat to 50°C, and then add silica and alumina (the weight ratio of sodium hydroxide solution to the total weight of silica and alumina is 2:1). Stir for 4 hours under a nitrogen atmosphere, then add the modified bentonite obtained in step S1, stir for 4 hours, age for 2 hours, and dry to obtain powder.

[0044] S3. Mix the powder obtained in step S2 with nano-calcium carbonate, sodium gluconate and γ-aminopropyltrimethoxysilane to obtain a roadbed soil solidifier.

[0045] Example 3

[0046] This embodiment provides a roadbed soil solidifier, comprising the following components in parts by weight: 50 parts magnesium-based bentonite, 0.5 parts hexadecyltrimethylammonium chloride, 50 parts silica, 20 parts alumina, 6 parts nano-calcium carbonate, 1 part sodium maleate, and 20 parts γ-glycidoxypropyltrimethoxysilane.

[0047] The preparation method of the subgrade soil stabilizer in this embodiment includes the following steps:

[0048] S1. Magnesium-based bentonite was dispersed in deionized water at a weight ratio of 1:10, then hexadecyltrimethylammonium chloride was added, and the mixture was stirred in a water bath at 60°C for 2 hours, allowed to stand for 14 hours, and dried to obtain modified bentonite.

[0049] S2. Add an 8% sodium hydroxide solution to the reactor, heat to 65°C, and then add silica and alumina (the weight ratio of sodium hydroxide solution to the total weight of silica and alumina is 2:1). Stir for 3 hours under a nitrogen atmosphere, then add the modified bentonite obtained in step S1, stir for 6 hours, age for 1 hour, and dry to obtain powder.

[0050] S3. Mix the powder obtained in step S2 with nano-calcium carbonate, sodium maleate, and γ-glycidoxypropyltrimethoxysilane to obtain a roadbed soil solidifier.

[0051] Comparative Example 1

[0052] The roadbed soil stabilizer in this comparative example is basically the same as that in Example 1, except that the roadbed soil stabilizer in this comparative example lacks calcium-based bentonite, and the weight parts of silica are adjusted to 74 parts and the weight parts of alumina are adjusted to 41 parts.

[0053] The preparation method of the roadbed soil stabilizer in this comparative example includes the following steps:

[0054] A roadbed soil solidifier is obtained by uniformly mixing hexadecyltrimethylammonium chloride, silicon dioxide, aluminum oxide, nano-calcium carbonate, sodium citrate, and γ-aminopropyltriethoxysilane.

[0055] Comparative Example 2

[0056] The roadbed soil stabilizer in this comparative example is basically the same as that in Example 1, except that the roadbed soil stabilizer in this comparative example lacks silica and the weight of alumina is adjusted to 70 parts.

[0057] Comparative Example 3

[0058] The roadbed soil stabilizer in this comparative example is basically the same as that in Example 1, except that the roadbed soil stabilizer in this comparative example lacks alumina and the weight of silica is adjusted to 70 parts.

[0059] Comparative Example 4

[0060] The roadbed soil stabilizer in this comparative example is basically the same as that in Example 1, except that the roadbed soil stabilizer in this comparative example lacks hexadecyltrimethylammonium chloride.

[0061] Comparative Example 5

[0062] The roadbed soil stabilizer in this comparative example is basically the same as that in Example 1, except that the roadbed soil stabilizer in this comparative example lacks nano-calcium carbonate, the weight of silica is adjusted to 50.1 parts, and the weight of alumina is adjusted to 27.9 parts.

[0063] Comparative Example 6

[0064] The roadbed soil stabilizer in this comparative example is basically the same as that in Example 1, except that the roadbed soil stabilizer in this comparative example lacks γ-aminopropyltriethoxysilane and the weight of calcium-based bentonite is adjusted to 60 parts.

[0065] Comparative Example 7

[0066] The roadbed solidifier in this comparative example is basically the same as that in Example 1, except that the preparation method of the roadbed soil solidifier in this comparative example is as follows: hexadecyltrimethylammonium chloride, silicon dioxide, alumina, nano calcium carbonate, sodium citrate and γ-aminopropyltriethoxysilane are mixed and stirred, then calcium-based bentonite is added and mixed evenly to obtain the roadbed soil solidifier.

[0067] Example 4

[0068] The subgrade soil solidifiers of Examples 1-3 and Comparative Examples 1-7 were applied to subgrade materials, with each 100 parts by weight of soil comprising 3 parts solidifier, 9 parts cement, 20 parts crushed stone and 15 parts water.

[0069] First, some water was added to the soil sample to bring the moisture content to approximately 14%. Then, a curing agent was added, and the sample was placed in a sealed bag and left to steep for 24 hours. After steeping, cement and the remaining water were added and stirred thoroughly. Then, according to JTG E51-2009 "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering", cylindrical specimens of Ф100mm×100mm were prepared, fully compacted, and placed in a standard curing chamber (temperature 20±2℃, relative humidity 95±2%) for 24 hours before demolding. For water-stabilized specimens, the specimens were cured in the standard curing chamber until the day before the desired curing age. On the last day of the curing period, the specimens were immersed in water for 24 hours. Non-water-stabilized specimens were cured directly to the specified age without immersion. Then, unconfined compressive strength tests were conducted on both water-stabilized and non-water-stabilized specimens using a fully automatic press. The loading rate of the press was controlled at 1mm / min. The 7-day unconfined compressive strength results are shown in Table 1. Strength loss rate = (P0-P) / P0*100%, where P0 is the strength of the non-water-stable specimen and P is the strength of the water-stable specimen.

[0070] Table 1 Results of 7-day unconfined compressive strength test of subgrade materials

[0071]

[0072]

[0073] As shown in Table 1, the 7-day unconfined compressive strength of the roadbed material using the curing agent of this invention is as high as 7.49 MPa, which meets the 7-day unconfined compressive strength specification requirements for actual highway construction. Furthermore, by comparing the strength of water-stabilized and non-water-stabilized specimens, it can be seen that the roadbed material of this invention has a low strength loss rate after immersion in water. This indicates that the roadbed material using the curing agent of this invention has high strength and excellent water stability.

[0074] Compared to Example 1, Comparative Example 1 lacked calcium-based bentonite, Comparative Example 2 lacked silica, Comparative Example 3 lacked alumina, and Comparative Example 4 lacked hexadecyltrimethylammonium chloride. The strength and water stability of the subgrade materials were significantly reduced, indicating that silica, alumina, and hexadecyltrimethylammonium chloride can significantly enhance the ability of bentonite to release water adsorbed on the surface of soil particles, thereby significantly improving the water stability and strength of the subgrade materials. The combined effect of the calcium-based bentonite, silica, alumina, and hexadecyltrimethylammonium chloride of this invention is necessary to significantly improve the strength and water stability of the subgrade materials. A comparison of Example 1 and Comparative Example 5 reveals that adding nano-calcium carbonate to the subgrade soil solidifier can significantly improve the unconfined compressive strength of the solidified soil. This may be because the addition of nano-calcium carbonate can optimize the hydration performance of cement and increase the content of ettringite, thereby enhancing the strength of the subgrade materials. Examples 1 and 6 show that the addition of a silane coupling agent significantly improves the unconfined compressive strength and water stability of the solidified soil. This is mainly because the silane coupling agent can chemically react with the bentonite and nano-calcium carbonate in the solidifier to enhance the bonding between the solidifier and the organic matter in the soil particles. Compared to Example 1, the preparation method of the solidifier in Comparative Example 7 simply involves blending the components, resulting in a significant decrease in the strength and water stability of the subgrade material.

[0075] Figure 1 The image shows a SEM image of the roadbed material using the curing agent of Example 1. As can be seen from the image, the roadbed material forms a dense, solidified whole, exhibiting excellent strength and water stability. Figure 2 The figures show the 7-day unconfined compressive strength curves of the roadbed materials in the examples and comparative examples. As can be seen from the figures, compared with comparative examples 1 to 7, the roadbed materials using the curing agent of the present invention have excellent strength and water stability.

[0076] By comparing Example 1 and Comparative Examples 1-7, it can be seen that when any component of the curing agent of the present invention is omitted or the preparation method of the curing agent is changed, the strength and water stability of the roadbed material will be significantly reduced. This is because the components of the present invention can synergistically reduce the adsorbed water in the soil, optimize the cement hydration performance, and tightly bind the soil particles together under specific methods, thereby significantly enhancing the water stability and strength of the solidified soil.

[0077] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A subgrade soil stabilizer characterized by, The components include the following components by weight: bentonite 40-50 parts, cetyltrimethylammonium chloride 0.5-2.5 parts, silicon dioxide 40-50 parts, aluminum oxide 20-30 parts, nano calcium carbonate 6-10 parts, ion complexing agent 1-3 parts, silane coupling agent 10-20 parts; The preparation method of the roadbed soil solidifying agent comprises the following steps: S1. The bentonite is dispersed in deionized water, then the cetyltrimethylammonium chloride is added, stirred at 60-70 DEG C water bath for 1-2 h, and then dried to obtain modified bentonite; S2. The sodium hydroxide solution is added to the container, heated to 50-65 DEG C, then the silicon dioxide and aluminum oxide are added, stirred for 3-4 h under the protection of the gas atmosphere, then the modified bentonite obtained in step S1 is added, stirred for 4-6 h, and then aged for 1-2 h, and then dried to obtain powder; S3. The powder obtained in step S2 is mixed with the nano calcium carbonate, ion complexing agent and silane coupling agent to obtain the roadbed soil solidifying agent.

2. The soil stabilizer according to claim 1, wherein The components include the following components by weight: bentonite 45 parts, cetyltrimethylammonium chloride 1.5 parts, silicon dioxide 45 parts, aluminum oxide 25 parts, nano calcium carbonate 8 parts, ion complexing agent 1.5 parts, silane coupling agent 15 parts.

3. The soil stabilizer according to claim 1, wherein The bentonite includes at least one of calcium-based bentonite, aluminum-based bentonite and magnesium-based bentonite.

4. The soil stabilizer according to claim 1, wherein The average particle size of the nano calcium carbonate is 60-80 nm.

5. The soil stabilizer according to claim 1, wherein The ion complexing agent includes at least one of sodium citrate, sodium gluconate and sodium maleate.

6. The soil stabilizer according to claim 1, wherein The silane coupling agent includes at least one of gamma-aminopropyl triethoxysilane, gamma-aminopropyl trimethoxysilane, gamma-glycidyl ether oxypropyl trimethoxysilane and vinyl trimethoxysilane.

7. A road base material using the solidifying agent according to any one of claims 1 to 6, characterized by The components include the following components by weight: solidifying agent 2-4 parts, cement 8-10 parts, gravel 15-25 parts and water 10-20 parts per 100 parts of soil.

8. The subbase material of claim 7, wherein, The components include the following components by weight: solidifying agent 3 parts, cement 9 parts, gravel 20 parts and water 15 parts per 100 parts of soil.

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