A soil stabilizer composition and its use

Abstract

The application relates to the technical field of soil solidification, and discloses a soil solidifying agent composition and application thereof. The soil solidifying agent composition contains the following components which are independently stored or stored in mixture of two or more: calcium hydroxide, anhydrous sodium sulfate, gypsum, polyacrylamide, slag and furnace ash; the polyacrylamide is cationic polyacrylamide with a molecular weight of 8-100 million; the average volume diameter of the slag is not more than 2 mm; and the average volume diameter of the gypsum is not more than 0.075 mm. Through the synergistic effect of inorganic excitation agents and organic polymers, the unconfined compressive strength and toughness of the solidified soil are significantly improved under the condition of low mixing amount, meanwhile, the industrial solid waste is used as a high-value-added resource, the application has the characteristics of low cost, good environmental protection and simple construction, and is suitable for the fields of roadbed engineering and foundation treatment.

Description

Technical Field

[0001] This invention relates to the field of soil stabilization technology, and more specifically to a soil stabilizing agent composition and its application. Background Technology

[0002] Soil stabilizers are materials that improve the engineering properties of soil through physical filling, chemical bonding, and ion exchange. They are widely used in civil engineering fields such as roadbeds, foundation treatment, and slope protection. Currently, traditional cementing materials such as cement and lime are mainly used for soil stabilization in engineering practice. Although these materials have stable stabilization effects and mature construction processes, they have high energy consumption and large carbon emissions during production, and are poorly adaptable to soft soils that are sensitive to water content. They are difficult to balance mechanical properties and engineering economics, which is in stark contrast to the current industrial orientation of green and low-carbon development.

[0003] With the increasing urgency of the demand for the resource utilization of industrial solid waste, the use of industrial by-products such as fly ash, steel slag, desulfurization gypsum, and furnace slag to replace part of the cement in the preparation of soil stabilizers has become a research hotspot. However, existing solid waste-based solidification materials generally suffer from the following technical bottlenecks: First, the solid waste materials themselves have low cementitious activity, and it is difficult to form sufficient structural strength in the short term when used alone. They must rely on chemical activators for activation, but existing activation systems are mostly concentrated on single alkali activation or sulfate activation, which has limited efficiency in releasing the potential activity of solid waste. Second, solid waste-based solidified soil usually exhibits problems such as high brittleness and obvious tendency to shrinkage and cracking, resulting in insufficient long-term durability and difficulty in meeting the requirements of high-standard engineering. Third, existing technologies are mostly limited to simple compounding between inorganic materials, lacking systematic synergistic design with organic polymer materials, and failing to give full play to the complementary and reinforcing effects between multiple components, resulting in significant room for improvement in the overall mechanical properties and construction adaptability of the solidified soil.

[0004] In summary, how to overcome the technical bottlenecks of existing solid waste-based soil stabilizers in terms of activity activation efficiency, synergistic improvement of mechanical properties, and engineering adaptability, and develop a new type of soil stabilizer material that can efficiently dispose of various industrial solid wastes and has excellent solidification and enhancement effects as well as good construction performance, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of existing solid waste-based soil stabilizers in terms of activity activation efficiency, synergistic improvement of mechanical properties, and engineering adaptability.

[0006] To achieve the above objectives, a first aspect of the present invention provides a soil stabilizer composition, wherein the soil stabilizer composition contains the following components, which are stored independently or in combination: Calcium hydroxide, anhydrous sodium sulfate, gypsum, polyacrylamide, slag, and furnace ash; Based on the total weight of the solid components of the soil stabilizer composition, the content of calcium hydroxide is 1-6 wt%, the content of anhydrous sodium sulfate is 1-6 wt%, the content of gypsum is 1-6 wt%, the content of polyacrylamide is 0.05-0.25 wt%, the content of slag is 40-55 wt%, and the content of furnace ash is 40-55 wt%. The polyacrylamide is a cationic polyacrylamide with a molecular weight of 8-10 million. The average volume diameter of the slag is no greater than 2 mm; The average volume diameter of the gypsum is no greater than 0.075 mm.

[0007] A second aspect of the present invention provides the application of the soil stabilizer composition of the first aspect in soil stabilization, wherein the application is carried out using the components of the soil stabilizer composition of the first aspect, including the step of mixing the components of the stabilizer composition with the soil to be stabilized, cement and water.

[0008] Compared with the prior art, the present invention has at least the following beneficial effects: (1) This invention effectively activates the potential cementitious properties of low-activity industrial solid wastes such as slag and ash through a composite activating system composed of calcium hydroxide and anhydrous sodium sulfate, promoting the formation of high-strength hydration products such as hydrated calcium silicate and ettringite. At the same time, the introduction of gypsum further enriches the sulfate source in the system, promotes the continuous formation of ettringite, and provides stable strength support for the solidified soil. Experiments show that under the condition of only 8-10% cement content, the unconfined compressive strength of the solidified soil can reach 1.55-2.22 MPa after 7 days, which is significantly better than that of traditional cement soil and single solid waste system, showing excellent early strength development ability.

[0009] (2) This invention introduces cationic polyacrylamide with a specific molecular weight. Through the adsorption and bridging effect of its long molecular chains, it effectively optimizes the microstructure between soil particles and hydration products, enhances the integrity and toughness of the soil, and significantly inhibits the tendency of drying shrinkage and cracking. The multi-scale synergistic effect of polyacrylamide and inorganic hydration products not only improves the mechanical properties of the solidified soil, but also improves its workability and long-term durability, overcoming the technical defects of existing solid waste-based solidification materials that are brittle and prone to cracking.

[0010] (3) This invention uses industrial solid waste such as slag, ash, and gypsum as the main raw materials to replace a large amount of cement and lime, significantly reducing material costs and carbon emissions, which is in line with the development direction of green, low-carbon and circular economy. By strictly controlling the particle size of slag, ash and gypsum, the solidification efficiency and material utilization rate are further improved, providing a feasible path for the large-scale disposal of industrial solid waste.

[0011] (4) The curing agent of the present invention is packaged in powder and liquid form, and each component can be stored independently or mixed as needed, which facilitates transportation, storage and on-site construction, and is suitable for various process scenarios such as road mixing and plant mixing. Its usage method is simple and convenient, requiring no additional special equipment, and has good engineering adaptability. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] As mentioned above, the first aspect of the present invention provides a soil stabilizer composition, wherein the soil stabilizer composition contains the following components, which are stored individually or in combination: Calcium hydroxide, anhydrous sodium sulfate, gypsum, polyacrylamide, slag, and furnace ash; Based on the total weight of the solid components of the soil stabilizer composition, the content of calcium hydroxide is 1-6 wt%, the content of anhydrous sodium sulfate is 1-6 wt%, the content of gypsum is 1-6 wt%, the content of polyacrylamide is 0.05-0.25 wt%, the content of slag is 40-55 wt%, and the content of furnace ash is 40-55 wt%. The polyacrylamide is a cationic polyacrylamide with a molecular weight of 8-10 million. The average volume diameter of the slag is no greater than 2 mm; The average volume diameter of the gypsum is no greater than 0.075 mm.

[0014] According to a preferred embodiment, the slag is incineration slag.

[0015] In a preferred embodiment, the furnace ash is the combustion ash of municipal solid waste, and the average volume diameter of the furnace ash is not greater than 0.075 mm.

[0016] In a preferred embodiment, the gypsum is dihydrate gypsum and / or desulfurized gypsum.

[0017] Preferably, the soil stabilizer composition of the present invention can be prepared by uniformly mixing the calcium hydroxide, the anhydrous sodium sulfate, the gypsum, the slag, the furnace ash and the polyacrylamide in a certain proportion. Each component can be stored independently and mixed as needed when used.

[0018] As previously stated, a second aspect of the present invention provides the application of the soil stabilizer composition of the first aspect in soil stabilization, wherein the application is carried out using the components of the soil stabilizer composition of the first aspect, including the step of mixing the components of the stabilizer composition with the soil to be stabilized, cement and water.

[0019] According to a preferred embodiment, the application of the present invention includes the following steps: (1) The soil to be solidified is pretreated to obtain pretreated soil with a moisture content of 13-17 wt%; (2) Dissolve polyacrylamide in water to obtain a polyacrylamide solution with a concentration of 0.1-0.2 wt%; (3) Calcium hydroxide, anhydrous sodium sulfate, gypsum, slag and ash are mixed in the first stage to obtain mixture I; (4) The cement, the mixture I, and the pretreated soil are mixed a second time to obtain mixture II; (5) Mix the mixture II with the polyacrylamide solution for a third time to obtain mixture III; (6) The mixture III is compacted and cured sequentially to obtain solidified soil; The soil stabilizer composition comprises the calcium hydroxide, anhydrous sodium sulfate, gypsum, polyacrylamide, slag, and ash. Based on the total weight of the solid components in the soil stabilizer composition, the weight of calcium hydroxide is 1-6 wt%, the weight of anhydrous sodium sulfate is 1-6 wt%, the weight of gypsum is 1-6 wt%, the weight of polyacrylamide is 0.05-0.25 wt%, the weight of slag is 40-55 wt%, and the weight of ash is 40-55 wt%.

[0020] Preferably, in step (1), the pretreatment includes: drying, crushing, and passing the soil to be solidified through a 4.75 mm sieve, taking the sieve-undersized portion, and then adding water to mix, so that the soil moisture content reaches 13-17 wt%.

[0021] Preferably, in step (3), the first mixing is carried out under stirring conditions, and at least the following conditions are met: the rotation speed is 150-250 rpm and the time is 5-10 min.

[0022] Preferably, in step (4), the second mixing is carried out under stirring conditions, and at least the following conditions are met: the rotation speed is 150-250 rpm and the time is 5-10 min.

[0023] Preferably, in step (5), the third mixing is carried out under stirring conditions, and at least the following conditions are met: the rotation speed is 150-250 rpm and the time is 5-10 min.

[0024] In a preferred embodiment, the total amount of solid components in the soil stabilizer composition is 7-22 wt% of the dry weight of the soil to be stabilized, and the amount of cement is 8-10 wt% of the dry weight of the soil to be stabilized.

[0025] More preferably, in step (4), the amount of cement used is 8-9 wt% of the dry weight of the soil to be solidified.

[0026] In a preferred embodiment, the conditions for maintenance in step (6) are: temperature 20±2℃, humidity ≥95%, and maintenance time ≥7 days.

[0027] In a preferred embodiment, the soil solidification includes soil solidification treatment in roadbed engineering, slope reinforcement engineering, and foundation treatment engineering.

[0028] The present invention will be described in detail below through examples. Unless otherwise specified, the raw materials used are all commercially available products.

[0029] Unless otherwise specified, "room temperature" or "room temperature" as used in this invention refers to a temperature of 22-28°C.

[0030] Polyacrylamide: Polyacrylamide I: This is a cationic polyacrylamide with a molecular weight of 8-10 million. It was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and its brand name is P875616. Polyacrylamide II: An anionic polyacrylamide with a molecular weight of 3 million, purchased from Sinopharm Chemical Reagent Co., Ltd., brand name 30149663; Polyacrylamide III: This is a cationic polyacrylamide with a molecular weight of 12 million. It was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and its brand name is P980885. Slag: Incineration slag, taken from a municipal solid waste incineration plant in Xiaoshan District, Hangzhou City, Zhejiang Province; Furnace ash: the ash from the combustion of municipal solid waste, taken from a municipal solid waste incineration plant in Xiaoshan District, Hangzhou City, Zhejiang Province; Cement: P·O42.5 grade, purchased from Wuxi Tianshan Cement Co., Ltd.

[0031] Application Example 1 This application example illustrates the use of the soil stabilizer composition provided by the present invention in soil stabilization, performed according to the following steps: (1) Pre-treat 10kg of soil to be solidified, including: drying, crushing, passing through a 4.75 mm sieve and taking the sieve-underfill portion, then adding water and mixing to obtain pre-treated soil with a moisture content of 15wt%. (2) Dissolve 1g of polyacrylamide (polyacrylamide I) in water to obtain a polyacrylamide solution with a concentration of 0.1wt%; (3) At room temperature, 40g of calcium hydroxide, 40g of anhydrous sodium sulfate, 40g of gypsum (dihydrate gypsum with an average volume diameter of 0.075mm), 400g of slag (with an average volume diameter of 2mm) and 400g of furnace ash (with an average volume diameter of 0.075mm) are mixed for 5 minutes at a speed of 200rpm to obtain mixture I. (4) At room temperature, 800g of cement, the mixture I and the pretreated soil are mixed for 5 minutes at a speed of 200rpm to obtain mixture II; (5) At room temperature, mix the mixture II with the polyacrylamide solution for 5 minutes at a speed of 200 rpm to obtain mixture III; (6) The mixture III was compacted in sequence (mixture III was placed in three layers into a mold with a diameter of 50 mm and a height of 50 mm, and each layer was compacted to a compaction degree of ≥93% to make a cylindrical specimen), and cured in a standard curing box for 7 days (temperature 20±2℃, humidity ≥95%) to obtain solidified soil, named P1.

[0032] Application Example 2 This application example uses a similar method to application example 1, except that the gypsum is desulfurized gypsum and the weight of some substances is different. Specifically, the weight of calcium hydroxide is 20g, the weight of anhydrous sodium sulfate is 10g, and the weight of cement is 1000g. Finally, the solidified soil was obtained and named P2.

[0033] Application Example 3 This application example uses a method similar to that of application example 1, except that the weight of some substances is different. Specifically, the weight of polyacrylamide is 2g, the weight of slag is 900g, the weight of ash is 900g, and the weight of cement is 1000g. Finally, the solidified soil was obtained and named P3.

[0034] Application Example 4 This application example uses a similar method to Application Example 1, except that the weight of cement used is 1000g. Finally, the solidified soil was obtained and named P4.

[0035] Comparative Example 1 This comparative example is carried out using a method similar to that of Application Example 1. The difference is that in step (3), the amount and weight of some substances are different. Specifically, the amount and weight of calcium hydroxide and anhydrous sodium sulfate are 0g. Finally, the solidified soil was obtained and named DP1.

[0036] Comparative Example 2 This comparative example was carried out using a method similar to that of Application Example 1, except that in step (2), the polyacrylamide used was polyacrylamide II; Finally, the solidified soil was obtained and named DP2.

[0037] Comparative Example 3 This comparative example was carried out using a method similar to that of Application Example 1, except that in step (2), the polyacrylamide used was polyacrylamide III; Finally, the solidified soil was obtained and named DP3.

[0038] Comparative Example 4 This comparative example is carried out using a method similar to that of Application Example 1, except that in step (3), the average volume diameter of the slag used is 4 mm; Finally, the solidified soil was obtained and named DP4.

[0039] Comparative Example 5 This comparative example is carried out using a method similar to that of Application Example 1, except that in step (3), the average volume diameter of the plaster used is 0.2 mm; Finally, the solidified soil was obtained and named DP5.

[0040] Comparative Example 6 This comparative example was conducted using a method similar to that of Application Example 1, except that the weight of some substances was different. Specifically, the weight of calcium hydroxide was 10g and the weight of anhydrous sodium sulfate was 5g. Finally, the solidified soil was obtained and named DP6.

[0041] Test Example 1 Unconfined compressive strength (UCS) tests were conducted on the soil stabilizers prepared in the above examples: The tests were conducted in accordance with the national standard "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG 3441-2024), and the results are shown in Table 1.

[0042] Table 1 Test Example 2 Direct shear tests were performed on the soil stabilizers prepared in the above examples: The tests were conducted in accordance with the national standard "Standard for Geotechnical Testing Methods" (GB / T 50123-2019), and the results are shown in Table 2.

[0043] Table 2 The above data show that the soil stabilizer composition provided by the present invention can enable the soil to achieve an unconfined compressive strength of up to 2.22 MPa after 7 days, and industrial by-product gypsum can replace calcium sulfate dihydrate, further broadening the utilization pathways of solid waste.

[0044] Through systematic comparative analysis of examples and comparative cases, the molecular weight of polyacrylamide is a key range for ensuring its good solubility, dispersibility, and excellent reinforcing effect. Too low a molecular weight results in insufficient reinforcing efficiency, while too high a molecular weight leads to difficulties in dissolution and dispersion, which is detrimental to strength development. Excessive inert solid waste particles dilute the effective cementing components in the system, potentially reducing the amount of cement per unit volume. Simultaneously, too many fine particles may require more water for wetting; improper water control can affect compaction and final strength.

[0045] The component ratios and physical parameter ranges determined by this invention through numerous experiments are the best guarantee for achieving high-strength and high-toughness solidified soil with low cement content. Any deviation from the preferred range will lead to a decrease in overall performance.

[0046] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A soil stabilizer composition, characterized in that, The soil stabilizer composition contains the following components, which may be stored individually or in combination: Calcium hydroxide, anhydrous sodium sulfate, gypsum, polyacrylamide, slag, and furnace ash; Based on the total weight of the solid components of the soil stabilizer composition, the content of calcium hydroxide is 1-6 wt%, the content of anhydrous sodium sulfate is 1-6 wt%, the content of gypsum is 1-6 wt%, the content of polyacrylamide is 0.05-0.25 wt%, the content of slag is 40-55 wt%, and the content of furnace ash is 40-55 wt%. The polyacrylamide is a cationic polyacrylamide with a molecular weight of 8-10 million. The average volume diameter of the slag is no greater than 2 mm; The average volume diameter of the gypsum is no greater than 0.075 mm.

2. The soil stabilizer composition according to claim 1, characterized in that, The slag is incineration slag.

3. The soil stabilizer composition according to claim 1 or 2, characterized in that, The furnace ash is the combustion ash of domestic waste, and the average volume diameter of the furnace ash is not greater than 0.075 mm.

4. The soil stabilizer composition according to claim 1 or 2, characterized in that, The gypsum is dihydrate gypsum and / or desulfurized gypsum.

5. The application of a soil stabilizer composition according to any one of claims 1-4 in soil stabilization, wherein the application is carried out using each component of the soil stabilizer composition according to any one of claims 1-4, characterized in that, This includes the step of mixing the components of the curing agent composition with the soil to be cured, cement, and water.

6. The application according to claim 5, characterized in that, Includes the following steps: (1) The soil to be solidified is pretreated to obtain pretreated soil with a moisture content of 13-17 wt%; (2) Dissolve polyacrylamide in water to obtain a polyacrylamide solution with a concentration of 0.1-0.2 wt%; (3) Calcium hydroxide, anhydrous sodium sulfate, gypsum, slag and ash are mixed in the first stage to obtain mixture I; (4) The cement, the mixture I, and the pretreated soil are mixed a second time to obtain mixture II; (5) Mix the mixture II with the polyacrylamide solution for a third time to obtain mixture III; (6) The mixture III is compacted and cured sequentially to obtain solidified soil; The soil stabilizer composition comprises the calcium hydroxide, anhydrous sodium sulfate, gypsum, polyacrylamide, slag, and ash. Based on the total weight of the solid components in the soil stabilizer composition, the weight of calcium hydroxide is 1-6 wt%, the weight of anhydrous sodium sulfate is 1-6 wt%, the weight of gypsum is 1-6 wt%, the weight of polyacrylamide is 0.05-0.25 wt%, the weight of slag is 40-55 wt%, and the weight of ash is 40-55 wt%.

7. The application according to claim 6, characterized in that, In step (3), the first mixing is carried out under stirring conditions, and at least the following conditions are met: the rotation speed is 150-250 rpm and the time is 5-10 min; and / or In step (4), the second mixing is carried out under stirring conditions, and at least meets the following requirements: a rotation speed of 150-250 rpm and a time of 5-10 min; and / or In step (5), the third mixing is carried out under stirring conditions, and at least the following conditions must be met: the rotation speed is 150-250 rpm and the time is 5-10 min.

8. The application according to claim 6, characterized in that, The total amount of solid components in the soil stabilizer composition is 7-22 wt% of the dry weight of the soil to be stabilized, and the amount of cement is 8-10 wt% of the dry weight of the soil to be stabilized.

9. The application according to claim 6, characterized in that, In step (6), the conditions for maintenance are: temperature 20±2℃, humidity ≥95%, and maintenance time ≥7 days.

10. The application according to claim 6 or 7, characterized in that, The soil solidification includes soil solidification treatment in roadbed engineering, slope reinforcement engineering, and foundation treatment engineering.

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