Method for preparing cured red clay expanding agent based on alkaline residues and application thereof

Abstract

The invention discloses a method for preparing a cured red clay expanding agent based on alkaline residues and application of the method, and relates to the technical field of resource utilization and preparation. The invention comprises XX. The expanding agent prepared from the alkaline residues is used for inhibiting the dry shrinkage of the red clay solidified soil. The expanding agent is prepared through a specific process, has good expansion performance and dry shrinkage inhibition effect, can significantly improve the performance of red clay solidified soil, and can significantly improve the expansibility and reaction activity of the expanding agent by combining the alkaline residues with the desulfurized gypsum and adopting a multi-step activation process. According to experimental data, under the condition that the doping amount of the expanding agent is 5%-10%, the expanding agent can reduce the dry shrinkage rate of solidified soil from 8.0% when the expanding agent is not doped to 0.6%-2.0%, the dry shrinkage inhibition effect can reach 70%-90%, and the obvious dry shrinkage inhibition effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of resource utilization and preparation, and in particular to a method for preparing a solidified red clay expansion agent based on alkali residue and application thereof. Background Art

[0002] In civil engineering and construction, solidified soil (especially solidified soil prepared using red clay) is often used in fields such as infrastructure construction, roadbed treatment and soil improvement. However, due to the high clay component contained in red clay, the water-bound water ratio is high during the hydration process, which leads to significant shrinkage of the solidified soil during the drying process. In order to solve this problem, shrinkage is usually suppressed by adding swelling agents in the prior art, and common swelling agents include cement, gypsum, etc. However, these swelling agents are often costly and have low resource utilization efficiency.

[0003] In some studies, alkali residue (e.g. from coal combustion and industrial waste) has been proposed as a potential low-cost raw material for improving the properties of soil and cement-based materials. However, the direct use of alkali residue usually leads to excessive alkalinity of the soil, and untreated alkali residue may produce adverse reactions in the soil, resulting in unstable soil properties, as follows:

[0004] (1) Shrinkage problem of red clay solidified soil:

[0005] Due to the high content of clay components in red clay and the large proportion of water-bound water, the solidified soil shrinks significantly during the hydration process, which not only affects the mechanical properties of the solidified soil, but may also have an adverse effect on the stability and service life of the structure.

[0006] Although existing expansion agents (such as gypsum, cement, etc.) can inhibit shrinkage to a certain extent, they usually need to be added in large quantities and are relatively costly.

[0007] (2) The cost of expansion agent is high and the resource utilization efficiency is low:

[0008] The raw materials of existing expansion agents are mostly high-cost materials such as cement and gypsum, which leads to an increase in the overall cost of the project.

[0009] Traditional expansion agents have limited sources and have a significant impact on the environment, especially during their production and transportation.

[0010] (3) The utilization rate of alkali slag resources is low and the treatment process is imperfect:

[0011] As an industrial by-product, alkali slag contains a large amount of sodium, calcium, silicon and other components. If it is directly used in solidified soil without treatment, it may cause the soil to be too alkaline, affecting the stability and mechanical properties of the soil.

[0012] The resource utilization of alkali slag has not been effectively developed, there is a waste problem, and the existing treatment methods are often not fully optimized.

[0013] Therefore, the existing technology still faces many technical bottlenecks in the resource utilization of alkali slag, the preparation of expansion agents and their application. There is an urgent need for a new expansion agent that can both inhibit the shrinkage of solidified soil and improve the utilization efficiency of alkali slag resources. Summary of the invention

[0014] The object of the present invention is to provide a method for preparing a solidified red clay expansion agent based on alkali residue and application thereof, so as to solve the problems in the background technology.

[0015] To achieve the above object, the present invention provides the following technical solution: a method for preparing a solidified red clay expansion agent based on alkali residue, comprising at least the following steps:

[0016] S1: alkali residue treatment and pretreatment, wherein the alkali residue treatment at least includes alkali residue soaking, and the pretreatment at least includes drying treatment;

[0017] S2: Grinding and refining: the dried alkali residue is put into a ball mill and ground until its particle size reaches 200 meshes to ensure a larger contact area between the expansion agent and the red clay and promote the reaction activity;

[0018] S3: Alkali residue is mixed with desulfurized gypsum to adjust the pH value;

[0019] S4: performing an expansion agent activation treatment, wherein the expansion agent activation treatment at least includes high temperature activation.

[0020] Furthermore, the alkali residue soaking comprises at least the following steps:

[0021] Mix the alkali residue and water in a mass ratio of 1:2;

[0022] Soak for 24 hours;

[0023] Intermittent stirring is performed to ensure that chloride ions and other soluble salts in the alkali residue are fully removed and the pH value is lowered.

[0024] Furthermore, the drying treatment comprises at least the following steps: drying the soaked alkali residue at a temperature of 80-100° C. for 4-6 hours until the moisture content of the alkali residue drops below 5%.

[0025] Furthermore, the specific surface area of ​​the alkali residue after S2 grinding increases by about 50%, and the particle size is uniform and the fineness is 200 mesh.

[0026] Furthermore, in S3, the ground alkali residue is mixed with desulfurized gypsum in a mass ratio of 9:1, and the pH value of the powder is further adjusted to 7.0-8.0 to ensure that it is suitable for reacting with red clay.

[0027] Furthermore, the high temperature activation comprises at least the following steps:

[0028] The mixed expansion agent is placed in a high temperature furnace at 300-500°C for activation;

[0029] The activation time is 2-4 hours to enhance the expansion properties of the expansion agent.

[0030] The invention discloses an application of preparing a solidified red clay swelling agent based on alkali residue, wherein the swelling agent prepared by a method for preparing a solidified red clay swelling agent based on alkali residue is mixed with red clay, and the mixing amount of the swelling agent and the red clay is 5% to 10%.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The swelling agent prepared by alkali residue of the present invention is used to inhibit the shrinkage of red clay solidified soil. The swelling agent is prepared by a specific process, has good swelling performance and shrinkage inhibition effect, and can significantly improve the performance of red clay solidified soil.

[0033] 2. The present invention combines alkali residue with desulfurized gypsum and adopts a multi-step activation process to significantly improve the expansibility and reactivity of the expansive agent. According to experimental data, when the expansive agent dosage is 5% to 10%, the expansive agent of the present invention can reduce the shrinkage rate of the solidified soil from 8.0% when the expansive agent is not added to 0.6% to 2.0%, and the shrinkage inhibition effect can reach 70% to 90%, which has a significant shrinkage inhibition effect;

[0034] 3. The present invention significantly improves the expansion property of the expansion agent by performing multi-step activation on the alkali residue. In the activated expansion agent, the main mineral components (such as hydrated calcium, etc.) are more reactive and can better react with solidifying materials such as cement, thereby enhancing its expansion effect and inhibiting the shrinkage of the solidified soil. In contrast, the expansion agents in the prior art usually lack such efficient activation treatment, resulting in limited expansion performance and a less significant shrinkage inhibition effect than the present invention;

[0035] 4. The present invention not only reduces the accumulation of waste but also reduces production costs through resource utilization of alkali slag. As an industrial waste, alkali slag has high alkalinity and mineral components. It can be effectively converted into expansion agent after activation and purification. This process not only reduces the impact of waste on the environment, but also provides economic value for the alkali slag. Through the expansion agent production method of the present invention, the production of 1 ton of expansion agent can reduce carbon dioxide emissions by about 0.2 tons, which has significant environmental benefits compared to traditional expansion agent production methods. Therefore, while achieving economic benefits, the present invention also has strong environmental advantages;

[0036] 5. The production cost of the swelling agent of the present invention is significantly reduced, and the shrinkage inhibition effect is better than that of the traditional swelling agent. Therefore, in future soil solidification projects, the material cost can be effectively reduced and the comprehensive benefits of the project can be improved. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] Embodiment 1:

[0039] A method for preparing a solidified red clay expansion agent based on alkali residue, comprising at least the following steps:

[0040] S1: alkali residue treatment and pretreatment, the alkali residue treatment at least includes alkali residue soaking, and the pretreatment at least includes drying treatment;

[0041] The present invention uses alkali residue as the raw material of the expansion agent for the first time. This practice can not only utilize the alkali residue waste, reduce environmental pollution, but also reduce the production cost of the expansion agent. As the source of waste, the present invention proposes a set of specific pretreatment and activation processes to make the alkali residue play a better role in the expansion agent and achieve the effect of inhibiting the shrinkage of red clay solidified soil. This step not only solves the environmental problem of waste, but also creates economic value for the waste, and provides a more sustainable and environmentally friendly raw material for the production of expansion agents.

[0042] S2: Grinding and refining: the dried alkali residue is put into a ball mill and ground until its particle size reaches 200 meshes to ensure a larger contact area between the expansion agent and the red clay and promote the reaction activity;

[0043] S3: Alkali residue is mixed with desulfurized gypsum to adjust the pH value;

[0044] S4: performing an expansion agent activation treatment, wherein the expansion agent activation treatment at least includes high temperature activation.

[0045] Alkali residue soaking includes at least the following steps:

[0046] Mix the alkali residue and water in a mass ratio of 1:2;

[0047] Soak for 24 hours;

[0048] Intermittent stirring is performed to ensure that the chloride ions and other soluble salts in the alkali residue are fully removed and the pH value is reduced. After soaking, the chloride ion content in the alkali residue is reduced to below 0.3% and the pH value is reduced to 7.0-9.0.

[0049] The drying treatment includes at least the following steps: drying the soaked alkali residue at a temperature of 80-100°C for 4-6 hours until the moisture content of the alkali residue drops below 5%. The weight of the dried alkali residue is reduced by about 25%, and the moisture content is reduced from 20% to 5%.

[0050] The specific surface area of ​​the alkali slag after S2 grinding increased by about 50%, the particle size was uniform, and the fineness was 200 mesh.

[0051] In S3, the ground alkali residue is mixed with desulfurized gypsum in a mass ratio of 9:1, and the pH value of the powder is further adjusted to 7.0-8.0 to ensure that it is suitable for reacting with red clay.

[0052] High temperature activation includes at least the following steps:

[0053] The mixed expansion agent is placed in a high temperature furnace at 300-500°C for activation;

[0054] The activation time is 2-4 hours to enhance the expansion of the expansion agent;

[0055] The expansion agent activated at high temperature has a 30% higher expansion capacity than the unactivated expansion agent through SEM and XRD analysis, which significantly increases its ability to react with solidified soil.

[0056] The activation treatment process of alkali residue (high temperature activation, grinding, mixing and other steps) adopts a multi-step activation process in the production process of the expansion agent, that is, soaking, drying, grinding, mixing with desulfurized gypsum and high temperature activation of the alkali residue. In particular, in the high temperature activation step of 300-500°C, the mineral components in the alkali residue undergo phase change, which significantly improves the expansion of the expansion agent. This activation process significantly improves the reactivity and expansion capacity of the expansion agent, ensures that the expansion agent can effectively inhibit shrinkage in red clay solidified soil, and improves the durability and stability of the expansion agent.

[0057] Embodiment 2:

[0058] An application of preparing a solidified red clay expansion agent based on alkali residue;

[0059] The swelling agent prepared in the above Example 1 is mixed with red clay.

[0060] Expansion agent dosage and mixing: According to the experimental results, the optimal dosage of the expansion agent is 5% to 10%. The expansion agent is fully mixed with the red clay according to this dosage, and after mechanical stirring, a standard sample is prepared and a 28-day shrinkage test is conducted. Detailed data of the 28-day shrinkage test:

[0061] Shrinkage calculation formula:

[0062] Shrinkage rate = (original size - shrinkage size) / original size × 100%

[0063] Experimental conditions: The sample size is 60mm x 60mm x 60mm, and the shrinkage effect is measured after 28 days of curing.

[0064] Expansive agent sample: After 28 days, the shrinkage was 8.0%, which is a common shrinkage rate for stabilized soil without expansive agent.

[0065] 5% expansion agent dosage: After 28 days, the shrinkage rate is reduced to 2.0%, which is about 75% lower than that of the sample without expansion agent.

[0066] 7% expansion agent dosage: After 28 days, the shrinkage rate dropped to 1.2%, which is about 85% lower than that of the sample without expansion agent.

[0067] 10% expansion agent dosage: After 28 days, the shrinkage rate dropped to 0.6%, which is about 90% lower than that of the sample without expansion agent, and the shrinkage inhibition effect is the most significant.

[0068] Optimization of alkali residue dosage and shrinkage inhibition effect

[0069] The present invention determines that the optimal dosage range of the expansion agent is 5% to 10%, and experimental data show that within this range, the expansion agent can reduce the 28-day shrinkage rate of the solidified soil from 8% to 0.6% to 2.0%, and the shrinkage inhibition effect reaches 70% to 90%, which significantly improves the stability of the solidified soil.

[0070] The optimization of the dosage of the expansive agent not only ensures that the expansive agent achieves the best shrinkage inhibition effect in the stabilized soil, but also avoids the cost increase and other performance problems that may be caused by excessive expansive agent.

[0071] Environmental benefits and low-cost advantages. The present invention not only effectively reduces the accumulation of alkali slag through resource utilization of alkali slag, but also significantly reduces the production cost of the expansion agent. For every ton of expansion agent produced, about 0.2 tons of carbon dioxide emissions can be reduced, which enhances the environmental advantages of the expansion agent. Compared with traditional expansion agents, the expansion agent production process of the present invention is more environmentally friendly, meets the requirements of sustainable development, and has lower production costs and strong market competitiveness.

[0072] The expansive agent of the present invention is applicable not only to red clay solidified soil, but also to other soil improvement, road construction and environmental protection projects. Its unique preparation process and efficient shrinkage inhibition effect enable it to play an effective role in different soil types. The wide applicability and low-cost characteristics of the expansive agent make it have great application potential in the fields of civil engineering and environmental protection, and can meet the needs of different projects.

[0073] Based on the above, the following comparison is proposed:

[0074] 1. Shrinkage inhibition effect:

[0075] In the prior art, common expansion agents (such as gypsum, cement, etc.) can inhibit the shrinkage of solidified soil to a certain extent, but due to their poor expansion or large addition amount, the shrinkage inhibition effect is usually limited. In practical applications, it often takes a longer curing time after adding gypsum, and its shrinkage inhibition effect will gradually weaken over time.

[0076] The expansive agent of the present invention can significantly improve the expansibility and reactivity of the expansive agent by combining alkali residue with desulfurized gypsum and adopting a multi-step activation process. According to experimental data, when the expansive agent dosage is 5% to 10%, the expansive agent of the present invention can reduce the shrinkage rate of the solidified soil from 8.0% when the expansive agent is not added to 0.6% to 2.0%, and the shrinkage inhibition effect can reach 70% to 90%, which has a significant shrinkage inhibition effect.

[0077] Experimental data

[0078] Alkali residue dosage Dimensions after shrinkage (mm) Shrinkage rate (%) No alkali residue 58.2x58.2x58.2 8.00％ 5% alkali residue 59.0x59.0x59.0 2.00％ 7% alkali residue 59.3x59.3x59.3 1.20％ 10% alkali residue 59.6x59.6x59.6 0.60％

[0079] These experimental data prove that the expansion agent of the present invention is significantly superior to the prior art in terms of shrinkage inhibition, especially in terms of long-term (28 days) shrinkage, showing a more stable and lasting inhibitory effect;

[0080] Effect of alkaline residue application on red clay solidification

[0081] The present invention verifies the practical application effect of adding alkali residue to red clay solidified soil through experiments. The solidified soil after adding the expansion agent not only effectively suppresses the shrinkage, but also has no cracks or other structural instability phenomena, showing the strengthening effect of the expansion agent on the solidified soil structure.

[0082] This effect of inhibiting shrinkage and improving structural stability makes alkali residue particularly suitable for soils with a high water-to-water ratio, such as red clay, enhancing the applicability and long-term stability of the soil.

[0083] 2. Optimize the activation process of the expansion agent to improve the expansion performance:

[0084] The expansion properties of existing expansion agents (such as conventional cement expansion agents or gypsum expansion agents) when used mainly depend on their initial mineral components and hydration process. However, in actual applications, the activation degree of these expansion agents is insufficient, which makes it difficult for the expansion properties to play an effective role in solidified soil.

[0085] Through this activation process, the expansibility of the expansive agent is significantly improved. In the activated expansive agent, the main mineral components (such as hydrated calcium, etc.) are more reactive and can better react with solidifying materials such as cement, thereby enhancing its expansion effect and inhibiting the shrinkage of the solidified soil. In contrast, the expansive agents in the prior art usually lack such efficient activation treatment, resulting in limited expansion performance and less significant shrinkage inhibition effect than the present invention.

[0086] 3. Comparison of waste resource utilization and environmental protection advantages:

[0087] In the prior art, many expansion agents are made from industrial byproducts, such as gypsum, slag, etc. These materials will generate more energy consumption and environmental pollution during the production process. In addition, the waste treatment cost is high and requires special treatment.

[0088] The present invention not only reduces the accumulation of waste but also reduces production costs through resource utilization of alkali residue. As an industrial waste, alkali residue has high alkalinity and mineral components and can be effectively converted into a swelling agent after activation and purification. This process not only reduces the impact of waste on the environment but also provides economic value for the alkali residue.

[0089] The expansion agent production method of the present invention can reduce carbon dioxide emissions by about 0.2 tons for every ton of expansion agent produced, which has significant environmental benefits compared to the traditional expansion agent production method. Therefore, the present invention has strong environmental advantages while achieving economic benefits.

[0090] 4. Wide applicability and low cost comparison:

[0091] Existing swelling agents usually have high production costs, and their performance is unstable in different soil types. The swelling agent of the present invention uses alkali residue as the main raw material, has a simple production process, low cost, and a wide range of applications. It can not only be widely used in red clay solidification soil, but also can be effectively used in other soil improvement, road construction and environmental protection projects.

[0092] The expansion agent production method of the present invention can significantly reduce production costs, and at the same time, the shrinkage inhibition effect is better than that of traditional expansion agents. Therefore, in future soil solidification projects, it is possible to effectively reduce material costs and improve the overall benefits of the project.

[0093] From the above analysis, it can be concluded that the significant advantages of the present invention compared with the prior art include:

[0094] Better shrinkage inhibition effect: When the expansion agent of the present invention is added in an amount of 5% to 10%, the shrinkage rate after 28 days can be reduced to 0.6% to 2.0%, and the inhibition effect reaches 70% to 90%, which is much better than the existing expansion agent.

[0095] Enhanced expansibility: A multi-step activation process is used to significantly improve the expansibility of the expansive agent, ensuring that it effectively inhibits shrinkage in the solidified soil.

[0096] Environmental protection and resource utilization: Through the resource utilization of alkali slag waste, not only the production cost is reduced, but also environmental benefits are achieved. The production of each ton of expansion agent can reduce carbon dioxide emissions by about 0.2 tons.

[0097] Low cost and wide applicability: The expansion agent of the present invention has low production cost and a wide range of applicability, and can be effectively applied to various soil improvement and soil consolidation projects.

[0098] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for preparing a solidified red clay expansion agent based on alkali residue, characterized in that: At least the following steps are included: S1: alkali residue treatment and pretreatment, wherein the alkali residue treatment at least includes alkali residue soaking, and the pretreatment at least includes drying treatment; S2: Grinding and refining: the dried alkali residue is put into a ball mill and ground until its particle size reaches 200 meshes to ensure a larger contact area between the expansion agent and the red clay and promote the reaction activity; S3: Alkali residue is mixed with desulfurized gypsum to adjust the pH value; S4: performing an expansion agent activation treatment, wherein the expansion agent activation treatment at least includes high temperature activation.

2. A method for preparing a solidified red clay expansion agent based on alkali residue according to claim 1, characterized in that: The alkali residue soaking comprises at least the following steps: Mix the alkali residue and water in a mass ratio of 1:2; Soak for 24 hours; Intermittent stirring is performed to ensure that chloride ions and other soluble salts in the alkali residue are fully removed and the pH value is lowered.

3. The method for preparing a solidified red clay expansion agent based on alkali residue according to claim 1, characterized in that: The drying treatment at least comprises the following steps: drying the soaked alkali residue at a temperature of 80-100° C. for 4-6 hours until the moisture content of the alkali residue drops below 5%.

4. The method for preparing a solidified red clay expansion agent based on alkali residue according to claim 1, characterized in that: The specific surface area of ​​the alkali residue after S2 grinding increases by 50%, the particle size is uniform, and the fineness is 200 meshes.

5. The method for preparing a solidified red clay expansion agent based on alkali residue according to claim 1, characterized in that: In the S3, the ground alkali residue and desulfurized gypsum are mixed in a mass ratio of 9:1, and the pH value of the powder is further adjusted to 7.0-8.0 to ensure that it is suitable for reacting with red clay.

6. The method for preparing a solidified red clay expansion agent based on alkali residue according to claim 1, characterized in that: The high temperature activation comprises at least the following steps: The mixed expansion agent is placed in a high temperature furnace at 300-500°C for activation; The activation time is 2-4 hours to enhance the expansion properties of the expansion agent.

7. An application of preparing solidified red clay expansion agent based on alkali residue, characterized in that: The swelling agent prepared by the method for preparing solidified red clay swelling agent based on alkali residue according to any one of claims 1 to 6 is mixed with red clay, and the mixing amount of the swelling agent and red clay is 5% to 10%.