A soil stabilizer and a method for preparing the same

Abstract

The application discloses a kind of soil solidifying agent and preparation method thereof, belong to building material technical field.The soil solidifying agent includes the following mass parts of raw materials: 80~100 portions HAS soil solidifying agent base material, 1~5 portions nano silicon dioxide, 0.5~3 portions triethanolamine, 0.1~1 portions anionic polyacrylamide and 0.5~2 portions sodium lignosulfonate.The application also discloses the preparation method of the soil solidifying agent, and the obtained product is suitable for the solidification treatment of various soil types such as soft clay, silt soil, tailings, etc.The formula of the application utilizes the high activity filling effect of nano silicon dioxide, the early hydration acceleration effect of triethanolamine, the space network bridging capacity of polyacrylamide and the dispersion and retarding function of sodium lignosulfonate, and each component synergistically acts, improves the solidification efficiency of the solidifying agent on high water content soil, and the early strength, water stability and freeze-thaw resistance are improved.

Description

Technical Field

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

[0002] Soil solidification technology is a technical means to improve the engineering properties of soil by adding cementing materials or chemical reagents. Its core objective is to improve the bearing capacity of soil, reduce compressibility, and improve water stability. Traditional soil solidification methods mainly use cement, lime and other cementing materials to directly mix the soil, but there are the following prominent problems: (1) Large amount of cement and high carbon emissions. When cement is used as the main solidification material, the amount usually needs to reach 10 to 15% of the dry weight of the soil to obtain the strength required by the project. Not only is the cost high, but the cement production process generates a large amount of carbon dioxide, which does not conform to the green and low-carbon development concept. (2) Poor adaptability to soils with high water content. When the soil water content exceeds 30%, the cement solidification effect decreases significantly, and the "spring soil" phenomenon is easy to occur, which makes it difficult to guarantee the construction quality. In high water content conditions such as river silt and municipal pipeline trench backfilling, traditional cement solidification methods often cannot meet the construction requirements. (3) Slow early strength development and long curing period. The early strength (7 days) of ordinary cement-stabilized soil is generally only 40-50% of the strength at 28 days, making it difficult to put into use quickly in municipal engineering projects and road repairs with tight schedules. (4) Insufficient freeze-thaw stability. In cold regions or seasonal freeze-thaw environments, traditional solidified soil has poor resistance to freeze-thaw cycles. After multiple freeze-thaw cycles, the strength loss is significant, affecting the durability of the project.

[0003] To address the aforementioned issues, HAS (Hydrogen Alkali) solidifiers, primarily made from industrial waste residue, have emerged. However, existing HAS solidifiers still have room for improvement in terms of curing strength, dispersion uniformity, and curing efficiency. Therefore, how to comprehensively improve the early strength, water stability, and durability of HAS soil stabilizers through scientific formulation design without significantly increasing costs is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] In view of the above-mentioned prior art, the present invention provides a soil stabilizer and its preparation method to solve the technical problems of poor adaptability of soil stabilizers to soils with high water content, low early strength, long curing time and poor freeze-thaw performance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is to provide a soil stabilizer, which comprises the following raw materials in parts by weight: 80-100 parts of HAS soil stabilizer base material, 1-5 parts of nano-silica, 0.5-3 parts of triethanolamine, 0.1-1 parts of anionic polyacrylamide, and 0.5-2 parts of sodium lignosulfonate; wherein the HAS soil stabilizer base material is made from slag and slag composition as the main raw materials, wherein the mass ratio of slag and slag composition is >80%, and the remainder is an alkaline activator.

[0006] Based on the above technical solution, the present invention can be further improved as follows.

[0007] Furthermore, the mixture contains 90 parts of HAS soil stabilizer base material, 3 parts of nano silica, 2 parts of triethanolamine, 0.5 parts of anionic polyacrylamide, and 1 part of sodium lignosulfonate.

[0008] Furthermore, the particle size of nano-silica is 5~50nm, and the specific surface area is 150~600m² / g.

[0009] Furthermore, the molecular weight of anionic polyacrylamide is 8 million to 18 million Da.

[0010] Furthermore, the alkaline activator is at least one of sodium carbonate, water glass, and sodium hydroxide.

[0011] This invention also discloses a method for preparing the above-mentioned soil stabilizer, which includes the following steps: S1: Mix HAS soil stabilizer base material, nano silica and sodium lignosulfonate according to the specified ratio and ball mill to obtain mixed powder; S2: Triethanolamine and anionic polyacrylamide are prepared into aqueous solutions to obtain a triethanolamine solution with a concentration of 10~30wt% and an anionic polyacrylamide aqueous solution with a concentration of 0.5~1.5wt%; S3: Add the aqueous solution obtained in step S2 to the mixed powder obtained in step S1, stir and disperse evenly, and then spray dry to obtain the final product.

[0012] Based on the above technical solution, the present invention can be further improved as follows.

[0013] Furthermore, in step S1, the ball milling time is 30~60 min, the ball milling medium is zirconia balls, and the ball-to-material ratio is 3:1~5:1.

[0014] The present invention also discloses the application of the above-mentioned soil stabilizer in soil stabilization.

[0015] Furthermore, the soil stabilizer is added to the soil to be treated at a dosage of 2-6% of the dry weight of the soil, mixed with water, and then cured after being rolled or vibrated into shape.

[0016] Furthermore, the soil to be treated includes at least one of soft clay, silty soil, fly ash, tailings, and roadbed fill; the curing conditions are: temperature of 10~35℃, relative humidity ≤90%, and curing time of 7~30 days.

[0017] The beneficial effects of this invention are: 1. This invention fully leverages the synergistic enhancement effect among five functional components through a rational formulation. Nano-silica provides a highly active silicon source, which reacts rapidly with calcium ions released during the hydration of the HAS curing agent to generate additional CSH gel, filling the pores; triethanolamine, as an organic early-strength agent, accelerates the depolymerization and hydration process of the slag glass network structure in the HAS base material, while simultaneously forming an early-strength-enhancing dual-effect synergy with nano-silica; anionic polyacrylamide forms a spatial network structure between soil particles through its long polymer chains, bridging the dispersed soil particles into a whole, compensating for the insufficient bonding of inorganic cementitious products when the spacing between soil particles is large; sodium lignosulfonate has water-reducing, dispersing, and air-entraining functions, reducing the viscosity of the slurry and improving the dispersion uniformity of each component in the soil. At the same time, its air-entraining effect forms micro-closed pores in the solidified body, effectively buffering freeze-thaw stress.

[0018] 2. The soil stabilizer prepared in this invention significantly improves early strength and also exhibits excellent water stability and freeze-thaw resistance. The composite soil stabilizer of this invention increases unconfined compressive strength by 64% at 7 days and by 43% at 28 days. This is mainly due to the combined effect of triethanolamine accelerating early hydration and the rapid filling effect of nano-silica. The softening coefficient reaches over 0.92, and the strength loss rate after immersion in water for 48 hours is less than 8%. The long-chain bonding effect of PAM effectively prevents water erosion at the interface between the cementitious products and soil particles, while the hydrophobic groups of sodium lignosulfonate further enhance the hydrophobic properties of the solidified body. After 25 freeze-thaw cycles, the mass loss rate of the stabilized soil of this invention is less than 2%, and the strength loss rate is less than 15%. The micropores introduced by sodium lignosulfonate and the interfacial bonding enhanced by PAM together endow the solidified body with excellent freeze-thaw durability. Detailed Implementation

[0019] The specific embodiments of the present invention will be described in detail below with reference to examples.

[0020] The raw materials used in the examples are from the following sources: HAS Soil Stabilizer Base Material: Purchased from Gezhouba Zhonggu Technology Co., Ltd., it is a Type II HAS soil stabilizer, with main components being granulated blast furnace slag (85wt%), sodium carbonate (10wt%), and water glass (5wt%), and a Blaine specific surface area of ​​450 m² / kg. Nano-silica: Purchased from Zhejiang Zhitai Nano-Micro New Materials Co., Ltd., with an average particle size of 20 nm and a specific surface area of ​​200 m² / g. Triethanolamine: Analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd. Anionic polyacrylamide: Molecular weight 12 million Daltons, degree of hydrolysis 25%, purchased from Shandong Yuanlin Silicon Sea Environmental Protection Technology Co., Ltd. Sodium lignosulfonate: Purchased from Taian City Taishan District Linsheng Wood Processing Plant, a brownish-yellow powder with a lignin content of not less than 55%.

[0021] Example 1 A soil stabilizer comprises the following raw materials in parts by weight: 90 parts HAS soil stabilizer base material, 3 parts nano silica, 2 parts triethanolamine, 0.5 parts anionic polyacrylamide and 1 part sodium lignosulfonate.

[0022] Preparation method: S1: HAS soil stabilizer base material, nano silica and sodium lignosulfonate are put into a ball mill for mixing and ball milling. Zirconia balls are used as the ball milling medium, the ball-to-material ratio is 4:1, and the ball milling is carried out for 45 minutes to obtain mixed powder. S2: Prepare a 20 wt% aqueous solution of triethanolamine and a 1 wt% aqueous solution of anionic polyacrylamide; S3: Mix the two aqueous solutions and add them to the mixed powder. Stir and disperse at 2000 r / min for 15 min. After spray drying (inlet air temperature 180℃, outlet air temperature 80℃), the product is obtained.

[0023] Example 2 A soil stabilizer comprises the following raw materials in parts by weight: 80 parts HAS soil stabilizer base material, 2 parts nano silica, 0.5 parts triethanolamine, 1 part anionic polyacrylamide and 0.5 parts sodium lignosulfonate.

[0024] Preparation method: S1: HAS soil stabilizer base material, nano silica and sodium lignosulfonate are put into a ball mill for mixing and ball milling. Zirconia balls are used as the ball milling medium, the ball-to-material ratio is 3:1, and the ball milling is 60 min to obtain mixed powder. S2: Prepare a 30 wt% aqueous solution of triethanolamine and a 1.5 wt% aqueous solution of anionic polyacrylamide; S3: Mix the two aqueous solutions and add them to the mixed powder. Stir and disperse at 2000 r / min for 15 min. After spray drying (inlet air temperature 180℃, outlet air temperature 80℃), the product is obtained.

[0025] Example 3 A soil stabilizer comprises the following raw materials in parts by weight: 100 parts HAS soil stabilizer base material, 5 parts nano silica, 3 parts triethanolamine, 0.1 parts anionic polyacrylamide and 2 parts sodium lignosulfonate.

[0026] Preparation method: S1: HAS soil stabilizer base material, nano silica and sodium lignosulfonate are put into a ball mill for mixing and ball milling. Zirconia balls are used as the ball milling medium, the ball-to-material ratio is 5:1, and the ball milling is carried out for 30 minutes to obtain mixed powder. S2: Prepare a 10 wt% aqueous solution of triethanolamine and a 0.5 wt% aqueous solution of anionic polyacrylamide; S3: Mix the two aqueous solutions and add them to the mixed powder. Stir and disperse at 2000 r / min for 15 min. After spray drying (inlet air temperature 180℃, outlet air temperature 80℃), the product is obtained.

[0027] Example 4 A soil stabilizer comprises the following raw materials in parts by weight: 90 parts HAS soil stabilizer base material, 4 parts nano silica, 1 part triethanolamine, 0.8 parts anionic polyacrylamide and 1.5 parts sodium lignosulfonate.

[0028] Preparation method: S1: HAS soil stabilizer base material, nano silica and sodium lignosulfonate are put into a ball mill for mixing and ball milling. Zirconia balls are used as the ball milling medium, the ball-to-material ratio is 4:1, and the ball milling is 50 min to obtain mixed powder. S2: Prepare a 15 wt% aqueous solution of triethanolamine and a 1 wt% aqueous solution of anionic polyacrylamide; S3: Mix the two aqueous solutions and add them to the mixed powder. Stir and disperse at 2000 r / min for 16 min. After spray drying (inlet air temperature 180℃, outlet air temperature 80℃), the product is obtained.

[0029] Comparative Example 1 is a pure HAS soil stabilizer base material (without any functional additives).

[0030] The raw materials and preparation methods of the soil stabilizers in Comparative Examples 2-5 are shown in Table 1. The process parameters in the preparation methods are the same as those in Example 1.

[0031] Table 1

[0032] Experimental Example Unconfined compressive strength was tested according to method T 0148 in JTG E40-2007 "Specifications for Geotechnical Tests of Highways"; water stability (softening coefficient) was tested according to the immersion method in T 0148 in JTG E40-2007; freeze-thaw cycles were conducted according to the slow freezing method in GB / T50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete", with water as the freeze-thaw medium, and each freeze-thaw cycle consisted of freezing at -18℃ for 6 hours and thawing at 20℃ for 6 hours.

[0033] ①The soil used for the test was taken from a municipal road construction site and was silty clay.

[0034] The soil described above was taken and its moisture content was adjusted to 18.6%. The soil stabilizer prepared in Examples 1 and Comparative Examples 1-5 was added at 3% of the soil dry weight. The stabilizer was first dry-mixed with the soil for 2 minutes, then wet-mixed with water for 3 minutes until homogeneous. The mixture was then placed into a mold (50mm diameter × 100mm height) in three layers, each layer was compacted 25 times, the surface was smoothed, and then sealed with plastic wrap. The mold was cured under standard conditions (temperature 20±2℃, relative humidity not less than 95%) until the specified age. After demolding, curing continued until the test age. The test results are shown in Table 2.

[0035] Table 2

[0036] The data in the table above show that the components of this invention can exert a synergistic effect. (1) Synergistic effect of nano-silica and triethanolamine: Comparing Comparative Examples 2, 3 and 4, it can be seen that adding nano-silica alone increases the 7-day strength by 19.7% (from 2.94 MPa to 3.52 MPa), adding triethanolamine alone increases the 7-day strength by 25.2% (from 2.94 MPa to 3.68 MPa), and adding both at the same time increases the 7-day strength by 34.4% (from 2.94 MPa to 3.95 MPa). Triethanolamine accelerates the depolymerization of slag glass to release more Ca². + And Ca² +The rapid formation of CSH gel with nano-silica, and the formation of gel further promotes the continuous hydration reaction, fully demonstrating the synergistic enhancement effect between the two. (2) Interfacial enhancement effect of anionic polyacrylamide: As can be seen from Comparative Examples 4 and 5, the strength increased from 3.95 MPa to 4.28 MPa after 7 days and from 6.25 MPa to 6.62 MPa after 28 days after the addition of anionic polyacrylamide. The enhancement mechanism of anionic polyacrylamide is different from that of inorganic cementing systems. It forms a bridge between soil particles and cementing products through long polymer chains, which belongs to interfacial bonding enhancement. This organic-inorganic composite enhancement effect is more significant in the early stage (7 days), indicating that anionic polyacrylamide plays a key role in the early stage of solidified structure formation. (3) Comprehensive synergistic effect of sodium lignosulfonate: Comparison of Comparative Example 5 and Example 1 shows that after adding sodium lignosulfonate, the 7-day strength increased from 4.28 MPa to 4.82 MPa (an increase of 12.6%), and the 28-day strength increased significantly from 6.62 MPa to 7.35 MPa (an increase of 11.0%). The synergistic effect of sodium lignosulfonate is significantly greater than the range that can be explained by its common water-reducing effect in cement systems. This indicates that in the composite system of the present invention, sodium lignosulfonate plays multiple synergistic roles: First, it improves the dispersion uniformity of nano-silica and anionic polyacrylamide in the mixed powder through water-reducing dispersion, so that each functional component can play its role; second, its retarding effect makes the hydration product generation rate more reasonable, avoiding the uneven product distribution caused by triethanolamine accelerating hydration; third, the micro-pore structure introduced by the air-entraining effect effectively alleviates the shrinkage stress inside the solidified body, reduces the generation of micro-cracks, and allows the 28-day strength to be fully utilized.

[0037] ② Using the same composite soil stabilizer formulation and preparation method as in Example 1, riverbed silty soil with a moisture content of 52% was treated. The stabilizer dosage was 4% of the dry weight of the silt. The stabilizer was directly added to the silt and mixed evenly with an excavator. After standing for 24 hours, samples were taken for testing. The 7-day unconfined compressive strength was 3.26 MPa, and the 28-day unconfined compressive strength was 5.42 MPa. The stabilized silt did not re-mudify upon contact with water, thus meeting the bearing capacity requirements of the construction platform.

[0038] ③ Durability verification The water stability and freeze-thaw cycle resistance of the solidified soil samples from Example 1 and Comparative Example 1 were tested, and the results are as follows: (1) Water stability test The samples cured for 28 days were immersed in water for 48 hours. After being removed and dried, their unconfined compressive strength was tested: Example 1 showed a strength of 6.89 MPa after immersion, with a softening coefficient of 6.89 / 7.35 = 0.937; Comparative Example 1 showed a strength of 4.36 MPa after immersion, with a softening coefficient of 4.36 / 5.13 = 0.850. The softening coefficient of the solidified soil of this invention is 10.2% higher than that of pure HAS solidifier.

[0039] (2) Freeze-thaw cycle test After 25 freeze-thaw cycles: Example 1 showed a mass loss rate of 1.2% and a strength loss rate of 12.4% (28-day strength decreased from 7.35 MPa to 6.44 MPa); Comparative Example 1 showed a mass loss rate of 3.8% and a strength loss rate of 24.8% (28-day strength decreased from 5.13 MPa to 3.86 MPa). The freeze-thaw mass loss rate of the solidified soil of this invention was reduced by 68.4%, and the strength loss rate was reduced by 50.0%.

[0040] While specific embodiments of the present invention have been described in detail, they should not be construed as limiting the scope of protection of the present invention. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of the present invention.

Claims

1. A soil stabilizer, characterized in that, The raw materials include the following parts by weight: 80-100 parts of HAS soil stabilizer base material, 1-5 parts of nano silica, 0.5-3 parts of triethanolamine, 0.1-1 parts of anionic polyacrylamide and 0.5-2 parts of sodium lignosulfonate; the HAS soil stabilizer base material is made from slag and slag composition as the main raw materials, wherein the mass ratio of slag and slag composition is >80%, and the remainder is an alkaline activator.

2. The soil stabilizer according to claim 1, characterized in that: 90 parts HAS soil stabilizer base material, 3 parts nano silica, 2 parts triethanolamine, 0.5 parts anionic polyacrylamide and 1 part sodium lignosulfonate.

3. The soil stabilizer according to claim 1 or 2, characterized in that: The nano-silica has a particle size of 5~50nm and a specific surface area of ​​150~600m² / g.

4. The soil stabilizer according to claim 1 or 2, characterized in that: The anionic polyacrylamide has a molecular weight of 8 million to 18 million Da.

5. The soil stabilizer according to claim 1 or 2, characterized in that: The alkaline activator is at least one of sodium carbonate, water glass, and sodium hydroxide.

6. The method for preparing the soil stabilizer according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Mix HAS soil stabilizer base material, nano silica and sodium lignosulfonate according to the specified ratio and ball mill to obtain mixed powder; S2: Triethanolamine and anionic polyacrylamide are prepared into aqueous solutions to obtain a triethanolamine solution with a concentration of 10~30wt% and an anionic polyacrylamide aqueous solution with a concentration of 0.5~1.5wt%; S3: Add the aqueous solution obtained in step S2 to the mixed powder obtained in step S1, stir and disperse evenly, and then spray dry to obtain the final product.

7. The method for preparing the soil stabilizer according to claim 6, characterized in that, In step S1, the ball milling time is 30-60 minutes, the ball milling medium is zirconia balls, and the ball-to-material ratio is 3:1-5:

1.

8. The application of the soil stabilizer according to any one of claims 1 to 5 in soil stabilization.

9. The application according to claim 8, characterized in that, Add the soil stabilizer to the soil to be treated at a dosage of 2-6% of the dry weight of the soil, add water and mix, then compact or vibrate to form the soil and then cure it.

10. The application according to claim 9, characterized in that, The soil to be treated includes one or more of the following: soft clay, silty soil, fly ash, tailings, and roadbed fill; the curing conditions are: temperature 10~35℃, relative humidity ≤90%, and curing time 7~30 days.

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