Alkali residue light solidified soil and roadbed construction method thereof

Abstract

The invention relates to the field of solidified soil, and particularly discloses alkaline residue light solidified soil and a roadbed construction method thereof. The alkaline residue light solidified soil comprises the following components in parts by mass: 40-50 parts of alkaline residue, 30-40 parts of soil material and 10-30 parts of fly ash, the roadbed construction method comprises the following steps: adding water into the alkaline residue light solidified soil, stirring to enable the water content in the alkaline residue light solidified soil to be 27-31%, paving the alkaline residue light solidified soil at a preset position for roadbed construction, respectively filling the two sides of the paved alkaline residue light solidified soil with edge covering soil with the thickness of more than 1m, and adopting clay with the plasticity index of 10-20 as the edge covering soil, and after completion, compacting and maintaining the paving area to obtain the alkaline residue light solidified soil roadbed. The alkaline residue light solidified soil has the advantage that the long-term durability of an alkaline residue solidified soil roadbed is improved.

Description

Technical Field

[0001] The present application relates to the field of solidified soil, and more specifically, to an alkali slag lightweight solidified soil and a roadbed construction method thereof. Background Art

[0002] With the continuous advancement of infrastructure construction, road engineering plays a vital role in transportation and economic development. As an important basic part of the road structure, the stability and durability of the roadbed are directly related to the performance and life of the road. Among the explorations and studies of many roadbed materials, alkali slag solidified soil as a new type of material has gradually attracted attention. As a new type of roadbed material, alkali slag solidified soil roadbed has many advantages in resource utilization, environmental protection and good engineering performance. It is one of the effective ways to solve the problem of alkali slag emissions and the dilemma of traditional roadbed materials.

[0003] Alkali residue mainly comes from the waste residue produced by the ammonia-soda process in the production of industrial soda ash. In the production of soda ash, about 0.3-0.5 tons of alkaline residue are produced for every ton of soda ash produced. With the development of the soda ash industry, the emission of alkaline residue is increasing. If it is not used reasonably, it will not only occupy a large amount of land resources, but also cause serious pollution to the environment. In view of the large-scale emission of alkaline residue and the problems of traditional roadbed materials, researchers began to explore the mixing and solidification of alkaline residue with other materials to form a new material that can be used for roadbed construction, namely alkaline residue solidified soil. By adding appropriate curing agents and adopting reasonable processes, the physical and mechanical properties of alkaline residue solidified soil can be adjusted to meet the engineering requirements of the roadbed.

[0004] In a long-term complex chemical environment, such as acid rain erosion and corrosive ions in groundwater, the cementitious substances in the alkali slag-stabilized soil are at risk of being destroyed by chemical reactions. After years of traffic loads and changes in the natural environment, microcracks will appear inside the alkali slag-stabilized soil roadbed. These microcracks will gradually expand over time, reducing the overall strength and stability of the roadbed. Summary of the invention

[0005] In order to improve the long-term durability of alkali slag solidified soil roadbed, the present application provides an alkali slag lightweight solidified soil and a roadbed construction method thereof.

[0006] The alkali residue lightweight solidified soil provided in this application adopts the following technical solution: A kind of alkali slag light solidified soil, the components of which include 40-50 parts of alkali slag, 30-40 parts of soil material and 10-30 parts of fly ash by weight.

[0007] By adopting the above technical scheme, fly ash contains a large amount of active silica and active alumina. In the alkaline environment of alkali slag solidified soil, they can react with alkaline substances such as calcium hydroxide to produce volcanic ash reaction, which has strong chemical stability. Calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) and other cementitious substances. These cementitious substances can fill the pores of soil particles to form a dense structure, reduce the contact area between corrosive substances such as acid rain and the internal components of alkali slag solidified soil, and thus reduce the probability of chemical reaction. Some components in alkali slag, such as calcium carbonate, react with acidic substances in acid rain to neutralize, which can reduce the erosion of acid rain on the internal structure of solidified soil to a certain extent. Although this neutralization effect is limited, it can provide preliminary protection for solidified soil to a certain extent. Through a reasonable mix ratio, alkali slag, soil and fly ash interact with each other to form a relatively stable overall structure. The soil provides a certain support and bearing capacity as a skeleton, and the cementitious reaction products of alkali slag and fly ash fill the pores of the soil, which enhances the density of the structure. This dense structure can prevent the rapid penetration of corrosive substances, slow down the progress of chemical reactions, and improve the durability of solidified soil in complex chemical environments. In addition, the synergistic effect of alkali slag, soil materials and fly ash can improve the strength of solidified soil. The cementitious substances generated by the volcanic ash reaction of fly ash increase the cohesive force of solidified soil, making the connection between soil particles tighter, thereby improving the compressive strength and shear strength of solidified soil. At the same time, this cementitious structure also has a certain toughness, which can absorb the stress generated by traffic loads and natural environmental changes to a certain extent, and reduce the generation of microcracks. The present application scheme can better cope with the long-term cumulative impact of environmental factors, maintain the overall strength and stability of the roadbed, extend the service life of the roadbed, reduce maintenance costs and frequency, and has significant long-term durability advantages.

[0008] Optionally, 2-4 parts of curing agent are also included.

[0009] Optionally, the curing agent is a cement-lime composite curing agent, which is a mixture of silicate cement and lime in a mass ratio of (1-2):1.

[0010] By adopting the above technical scheme, the main components of silicate cement, such as tricalcium silicate and dicalcium silicate, will generate a large amount of calcium hydroxide and hydrated calcium silicate gel during the hydration process. Calcium hydroxide can provide an alkaline environment, stimulate the active components in alkali slag and fly ash, and promote the volcanic ash reaction. The hydrated calcium silicate gel has a strong cementing ability, can fill pores, and improve the strength and density of the solidified soil. For example, the calcium hydroxide produced by cement hydration reacts with the active silicon dioxide in the alkali slag to generate more hydrated calcium silicate, which enhances the structural strength of the solidified soil. Lime can not only further provide an alkaline environment and enhance the stimulation of the activity of the alkali slag, but also react with carbon dioxide in the air to generate calcium carbonate, which increases the strength and volume stability of the solidified soil. In addition, the calcium ions in the lime can undergo ion exchange reactions with clay minerals in the soil material, improve the structure and properties of the soil, and increase the bonding force between soil particles. When cement and lime are compounded in a mass ratio of (1-2):1, the two can play a synergistic role of complementary advantages. The early strength and hydration products provided by cement provide the basis for subsequent reactions, while lime continues to play a role in the long-term process, further enhancing the strength and durability of the solidified soil through slow carbonization reaction and continuous stimulation of the activity of alkali slag. This synergistic effect enables the solidified soil to maintain good performance development at different ages, with both rapid early strength growth to meet the construction schedule requirements and good late strength growth and durability to meet the needs of long-term use of the roadbed.

[0011] Optionally, the curing agent is a red mud-carbide slag composite curing agent, and the preparation method of the red mud-carbide slag composite curing agent is: The red mud is dried to reduce its water content to 20-30%, the dried red mud is crushed, and after crushing, it is sieved through a 100-mesh sieve, and then the sieved red mud is mixed with water in a mass ratio of 1: (3-5), stirred evenly, and then allowed to stand for 1-2 hours, and the upper alkaline aqueous solution is separated by filtration, and the separated red mud is repeatedly washed with water until the pH value of the red mud drops to 10-11; The carbide slag is dried to a moisture content of 10-20%, the dried carbide slag is ground, and after grinding, it is passed through an 80-mesh sieve; Red mud and carbide slag are mixed in a mass ratio of (1-3):1, and sodium lignin sulfonate is added in an amount of 1-5% of the total mass of the red mud and carbide slag during the mixing process to obtain a red mud-carbide slag composite curing agent.

[0012] By adopting the above technical solution, the red mud is dried until the water content is reduced to 20-30%, and then crushed and sieved, so that the particle size of the red mud can be made more uniform and fine, and its specific surface area is increased. This is conducive to more sufficient contact and reaction of the red mud when it is mixed with other materials in the future. The fine particles can better fill the pores between the particles of alkali slag, soil and fly ash, thereby improving the density of the solidified soil. The appropriate water content can ensure that the hydration reaction and volcanic ash reaction between the curing agent and other materials can proceed smoothly, thereby improving the strength and durability of the solidified soil. The red mud is washed and its pH value is reduced to 10-11, which reduces the strong alkalinity of the red mud and its potential harm to the environment. During the use of the alkali slag solidified soil roadbed, excessive alkalinity will lead to alkalinization of the surrounding soil and water bodies, affecting the ecological balance. By reducing the alkalinity through water washing, the solidified soil is improved in terms of environmental friendliness. On the other hand, the water washing process can remove some soluble salts and other impurities in the red mud. After removing impurities, the purity of red mud is improved, and its role in solidified soil is more stable and effective. It can better participate in the reaction with carbide slag and other materials, and improve the quality and durability of solidified soil. Drying carbide slag to a moisture content of 10-20% and grinding it through an 80-mesh sieve can make the particles of carbide slag finer and more uniform. Fine particles increase the specific surface area of ​​carbide slag and improve its reactivity. When mixed with red mud and other materials, carbide slag can react more quickly with the components in red mud, alkali slag, soil materials, etc. Red mud and carbide slag are mixed in a mass ratio of (1-3):1, and sodium lignin sulfonate is added, so that the two can fully exert their synergistic effect. The aluminum oxide in the red mud can react with the calcium hydroxide in the carbide slag to form hydrated calcium aluminate, and the silicon oxide can react with calcium hydroxide to form hydrated calcium silicate. These gelling substances are intertwined to form a solid network structure, which tightly bonds the particles of alkali slag, soil materials and fly ash together, significantly improving the strength and durability of solidified soil. The addition of sodium lignin sulfonate plays the role of a dispersant, which can improve the dispersibility of red mud and carbide slag particles during the mixing process and prevent particle agglomeration. This makes the composite curing agent more uniform when mixed with other materials, further improving the uniformity of the performance of the solidified soil. Using red mud and carbide slag as the main components of the curing agent realizes the resource utilization of industrial waste. Applying them to the alkali slag solidified soil roadbed not only solves the problem of waste disposal, but also reduces the raw material cost of the curing agent. It is also in line with the concept of sustainable development and has significant environmental and social benefits.

[0013] Optionally, the alkali slag with a particle size of >0.6 mm accounts for 20-30% of the total alkali slag, the alkali slag with a particle size of 0.1-0.6 mm accounts for 30-40% of the total alkali slag, and the alkali slag with a particle size of <0.1 mm accounts for 30-50% of the total alkali slag.

[0014] By adopting the above technical scheme, alkali slag of different particle size ranges are reasonably matched to form a relatively good particle gradation. Among them, alkali slag particles with a particle size of more than 0.6mm can serve as a skeleton support structure, provide a preliminary space framework for the solidified soil, bear a certain load and disperse stress, and prevent the solidified soil from excessive deformation when subjected to force. Alkali slag particles with a particle size of 0.1-0.6mm are filled in the pores between large particles, further optimizing the void structure between particles, reducing the porosity of the solidified soil and improving the density. This filling action increases the contact points and friction between particles, thereby enhancing the integrity of the solidified soil. At the same time, the tighter particle arrangement also reduces the channels for water penetration and improves the impermeability of the solidified soil. Alkali slag particles with a particle size of less than 0.1mm can be filled into smaller pores, further refining and compacting the microstructure of the solidified soil. Based on the good particle gradation, the solidified soil can maintain good stability and strength when subjected to traffic loads and natural environmental factors for a long time.

[0015] Optionally, the soil material includes 30-40% clay, 30-40% silty sand, 10-20% bentonite, and 1-10% humus.

[0016] By adopting the above technical solution, the stable structure formed by the cooperation of clay, silty sand, bentonite and humus enables the solidified soil to maintain good performance during long-term use. This stable structure can resist the long-term effects of natural environmental factors and traffic loads, and reduce the performance degradation caused by long-term stress and environmental influences. Among them. Humus contains functional groups that can form hydrogen bonds with water molecules, and synergize with bentonite to improve the water absorption and water retention of the solidified soil, making the water distribution in the soil more uniform, which is conducive to the solidification reaction. In addition, its functional groups can react with the metal ions on the surface of the soil particles to enhance the bonding force between the soil particles, and can also participate in the solidification reaction, promote the formation of gelling substances, and thus improve the strength of the solidified soil.

[0017] In the second aspect, the present application provides a method for constructing an alkali slag lightweight solidified soil roadbed, which adopts the following technical solution: A method for constructing an alkali slag lightweight solidified soil roadbed comprises the following steps: Add water to the alkali slag lightweight solidified soil and stir it to make the water content in the alkali slag lightweight solidified soil 27-31%, and lay the alkali slag lightweight solidified soil at the predetermined position of the roadbed construction. Fill the sides of the laid alkali slag lightweight solidified soil with a thickness of more than 1m. The edge soil uses clay with a plasticity index of 10-20. After completion, compact and maintain the paving area to obtain the alkali slag lightweight solidified soil roadbed.

[0018] By adopting the above technical solution, by controlling the water content of the alkali slag lightweight solidified soil at 27-31%, it can be ensured that the materials are fully mixed and have good workability during the mixing process. At the same time, in the subsequent compaction process, the moderate water content can not only provide a certain lubrication effect for compaction, making it easier for the compaction equipment to compact the solidified soil to the required density of the design, but also will not cause poor compaction phenomena such as spring soil due to excessive water, thus ensuring the compaction quality of the roadbed. Using clay with a thickness of more than 1m and a plasticity index of 10-20 as the edge soil can provide good lateral constraints for the alkali slag lightweight solidified soil. This clay has a certain cohesion and internal friction, forming a stable barrier on both sides of the roadbed. When the alkali slag lightweight solidified soil roadbed is subjected to traffic loads or natural forces, the edge soil can effectively limit the lateral deformation and displacement of the solidified soil, prevent the collapse and sliding of the roadbed slope, and improve the overall stability of the roadbed.

[0019] Optionally, when the alkali residue lightweight solidified soil contains a curing agent, water is added and stirred so that the water content in the alkali residue lightweight solidified soil is 29-31%; when the alkali residue lightweight solidified soil does not contain a curing agent, water is added and stirred so that the water content in the alkali residue lightweight solidified soil is 27-29%.

[0020] By adopting the above technical solution, the appropriate water content can make the curing agent particles evenly dispersed and better dissolved in the alkali slag lightweight solidified soil, accelerating the rate of chemical reaction. If the water content is too low, the hydration reaction of the curing agent will be restricted, resulting in insufficient production of cementitious substances, affecting the strength development of the solidified soil; while if the water content is too high, the solidified soil may bleed after construction, affecting the uniformity and density of the solidified soil, thereby reducing its strength and durability.

[0021] When the alkali residue lightweight solidified soil does not contain a curing agent, the relatively low water content can prevent the soil from being too muddy due to excessive water, affecting the construction operation and the initial strength of the solidified soil. And the lower water content helps to reduce the volume change of the solidified soil after construction and during use. If the water content is too high, the solidified soil may shrink greatly due to water evaporation during the drying process, resulting in cracks. Controlling the water content at 27-29% can reduce the shrinkage rate of the solidified soil and reduce the risk of crack formation.

[0022] In summary, this application has the following beneficial effects: 1. Since this application uses alkali slag and soil materials to form a stable structure through a reasonable mix ratio, soil materials are used as the skeleton, and the alkali slag and fly ash cement products fill the pores, enhance the density, prevent the penetration of erosive substances, and improve durability. At the same time, the three work together to improve the strength of the solidified soil, the fly ash volcanic ash reaction increases the bonding force, the cementitious structure is tough, absorbs stress and reduces micro cracks, can cope with long-term environmental impacts, maintain the strength and stability of the roadbed, extend the life, reduce maintenance costs, and have significant long-term durability advantages.

[0023] 2. In the present application, a curing agent preferably is used in which red mud and carbide slag are mixed in a mass ratio of (1-3):1. Through synergistic action, cementitious substances such as hydrated calcium aluminate and hydrated calcium silicate are generated to form a solid network structure to improve the strength and durability of the cured soil. Sodium lignin sulfonate also improves the particle dispersibility and performance uniformity. Using red mud and carbide slag as the main components of the curing agent realizes the resource utilization of waste and reduces costs. It has significant environmental and social benefits, and overall improves the performance and sustainability of the alkali slag cured soil roadbed.

[0024] 3. The roadbed construction method of the present application controls the water content of the alkali slag lightweight solidified soil to ensure that the materials are fully mixed and have good workability during stirring, provide lubrication for compaction, ensure compaction quality, promote or adapt to the solidification reaction, and avoid strength, uniformity and durability problems caused by improper water content. Clay with a thickness of more than 1m and a plasticity index of 10-20 is used as the edge soil to provide lateral constraints for the solidified soil, and a stable barrier is formed by its cohesion and internal friction, which effectively limits the lateral deformation and displacement of the solidified soil, prevents slope collapse and sliding, improves the overall stability of the roadbed, and reduces the risk of volume changes and cracks in the solidified soil, thereby improving the quality of roadbed construction and long-term durability, meeting the actual needs of the project and having certain flexibility and adaptability. DETAILED DESCRIPTION

[0025] The present application is further described in detail below in conjunction with the examples. It is particularly noted that if no specific conditions are specified in the following examples, the experiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0026] Preparation example of red mud-carbide slag composite curing agent Preparation Example 1 The preparation method of red mud-carbide slag composite curing agent is: Place the red mud in an oven and dry it at 80°C until the water content of the red mud is reduced to 25±5%. Use a ball mill to crush the dried red mud, and pass the crushed red mud through a 100-mesh sieve. The unscreened red mud particles are re-grinded and sieved until all pass. Mix the sieved 50kg of red mud powder with 200kg of water and stir it in a blender at 1200r / min for 30min. After stirring, let the mixture stand for 1.5h to allow the red mud particles to fully precipitate in the water and form an alkaline aqueous solution on the upper layer. Use a filter press to separate the upper alkaline aqueous solution, and wash the separated red mud several times. After each wash, the pH value of the red mud should be tested until the pH value of the red mud drops to 10-11.

[0027] Place the carbide slag in a drying oven and dry it with 80℃ hot air. Regularly test the moisture content of the carbide slag until the moisture content is 15±5% and stop drying. Use a ball mill to grind the dried carbide slag. After completion, pass the carbide slag through an 80-mesh sieve to remove large particles that do not meet the requirements and grind them again until they pass the sieve.

[0028] The pretreated 20 kg red mud and 10 kg carbide slag were stirred at a speed of 300 r / min using a mixer, and 0.4 kg sodium lignin sulfonate was added during the stirring process. The mixture was stirred for 30 minutes to obtain a red mud-carbide slag composite curing agent.

[0029] Preparation Example 2 The preparation method of the red mud-carbide slag composite curing agent is as follows: the difference from Preparation Example 1 is that 10 kg of pretreated red mud and 10 kg of carbide slag are mixed and stirred.

[0030] Preparation Example 3 The preparation method of the red mud-carbide slag composite curing agent is as follows: the difference from Preparation Example 1 is that 30 kg of pretreated red mud and 10 kg of carbide slag are mixed and stirred.

[0031] Preparation Example 4 The preparation method of the red mud-carbide slag composite curing agent is as follows: the difference from Preparation Example 1 is that 0.3 kg of sodium lignin sulfonate is added during the stirring process.

[0032] Preparation Example 5 The preparation method of the red mud-carbide slag composite curing agent is as follows: the difference from Preparation Example 1 is that 0.5 kg of sodium lignin sulfonate is added during the stirring process.

[0033] Preparation Example 5 The preparation method of the red mud-carbide slag composite curing agent is as follows: the difference from Preparation Example 1 is that the red mud is not subjected to subsequent treatment after screening, but is directly mixed with the pretreated carbide slag. Example

[0034] Example 1 A method for constructing an alkali slag lightweight solidified soil roadbed: In this embodiment, the alkali residue is obtained by recycling waste materials, and the alkali residue contains 21.45% calcium carbonate, 15% calcium chloride, 2.21% sodium chloride, 3.12% silicon, 0.70% iron, 0.79% aluminum, 7.82% magnesium, and 0.41% sulfur. The alkali residue with a particle size of more than 0.6 mm accounts for 25% of the total alkali residue, the alkali residue with a particle size of 0.1-0.6 mm accounts for 35% of the total alkali residue, and the alkali residue with a particle size of less than 0.1 mm accounts for 40% of the total alkali residue. The soil material contains 35% clay, 40% silty sand, 15% bentonite and 10% humus. The plasticity index of the clay is 10-20, and the particle size of the silty sand is 0.075-0.25mm.

[0035] Mix 450 kg of alkali slag, 350 kg of soil material and 200 kg of fly ash in a mixing tank for 30 minutes to obtain alkali slag lightweight solidified soil.

[0036] Add water to the alkali slag lightweight solidified soil and stir it to make the water content in the alkali slag lightweight solidified soil be 28%. Lay the alkali slag lightweight solidified soil at the predetermined position of the roadbed construction. Fill both sides of the laid alkali slag lightweight solidified soil with a thickness of 1.5m. The edge soil uses clay with a plasticity index of 10-20. After completion, compact and maintain the paving area to obtain the alkali slag lightweight solidified soil roadbed.

[0037] Example 2 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 1 is that 400 kg of alkali slag, 300 kg of soil material, and 100 kg of fly ash are mixed in a mixing tank for 30 minutes to obtain alkali slag lightweight solidified soil.

[0038] Example 3 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 1 is that 500 kg of alkali slag, 400 kg of soil material, and 300 kg of fly ash are mixed in a mixing tank for 30 minutes to obtain alkali slag lightweight solidified soil.

[0039] Example 4 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 1 is that 450 kg of alkali slag, 350 kg of soil, 200 kg of fly ash, and 30 kg of solidifying agent are mixed in a stirring tank for 30 minutes to obtain alkali slag lightweight solidified soil.

[0040] Among them, the curing agent is a cement-lime composite curing agent which is a mixture of silicate cement and lime in a mass ratio of 1.5:1.

[0041] Example 5 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 4 is that 450 kg of alkali slag, 350 kg of soil, 200 kg of fly ash, and 20 kg of solidifying agent are mixed in a stirring tank for 30 minutes to obtain alkali slag lightweight solidified soil.

[0042] Example 6 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 4 is that 450 kg of alkali slag, 350 kg of soil, 200 kg of fly ash, and 40 kg of solidifying agent are mixed in a stirring tank for 30 minutes to obtain alkali slag lightweight solidified soil.

[0043] Example 7 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 4 is that the curing agent is a cement-lime composite curing agent, which is a mixture of silicate cement and lime in a mass ratio of 1:1.

[0044] Example 8 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 4 is that the curing agent is a cement-lime composite curing agent, which is a mixture of silicate cement and lime in a mass ratio of 2:1.

[0045] Example 9 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 4 is that a red mud-carbide slag composite solidifier is used as the solidifier, and the red mud-carbide slag composite solidifier is prepared by Preparation Example 1.

[0046] Embodiment 11 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 9 is that a red mud-carbide slag composite solidifier is used as the solidifier, and the red mud-carbide slag composite solidifier is prepared by Preparation Example 2.

[0047] Example 12 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 9 is that a red mud-carbide slag composite solidifier is used as the solidifier, and the red mud-carbide slag composite solidifier is prepared by Preparation Example 3.

[0048] Embodiment 13 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 9 is that a red mud-carbide slag composite solidifier is used as the solidifier, and the red mud-carbide slag composite solidifier is prepared by Preparation Example 4.

[0049] Embodiment 14 A method for constructing an alkali slag lightweight solidified soil roadbed: The method is different from Example 1 in that water is added to the alkali slag lightweight solidified soil and stirred to make the water content of the alkali slag lightweight solidified soil 30%.

[0050] Embodiment 15 A method for constructing an alkali slag lightweight solidified soil roadbed: The method is different from Example 9 in that water is added to the alkali slag lightweight solidified soil and stirred to make the water content of the alkali slag lightweight solidified soil 30%.

[0051] Comparative Example Comparative Example 1 A method for constructing an alkali slag lightweight solidified soil roadbed: The difference from Example 9 is that the red mud-carbide slag composite solidifying agent is prepared by Preparation Example 5.

[0052] Comparative Example 2 A method for constructing an alkali slag lightweight solidified soil roadbed: The method is different from Example 9 in that ordinary Portland cement is used as the solidifying agent.

[0053] Comparative Example 3 A method for constructing an alkali slag lightweight solidified soil roadbed: The method is different from Example 1 in that humus is not added to the soil material, and the proportions of other components remain unchanged.

[0054] Performance testing Detection Methods Two 100 mm×100 mm×100 mm alkali slag lightweight solidified soil specimens were made from the alkali slag lightweight solidified soil obtained in each embodiment and comparative example, and the specimens were cured to a specified age.

[0055] First, one of the specimens was tested for compressive strength.

[0056] Another specimen was placed in a freeze-thaw test chamber, frozen at -20°C for 6 hours, and then thawed in 20°C water for 6 hours, as one freeze-thaw cycle.

[0057] After 20 freeze-thaw cycles, the specimens were taken out and their appearance changes were observed, such as whether there were cracks, peeling, etc. At the same time, the compressive strength of the specimens was tested and the strength loss rate was calculated.

[0058] Table 1 Test data

[0059] It can be seen from Examples 9-13 and Comparative Examples 1-2 and Table 1 that washing red mud and reducing its pH value to 10-11 reduces the strong alkalinity of red mud and reduces its potential harm to the environment. During the use of alkali slag solidified soil roadbed, excessive alkalinity can lead to alkalinization of surrounding soil and water bodies, affecting the ecological balance. Reducing alkalinity by washing can improve the environmental friendliness of solidified soil. On the other hand, the washing process can remove some soluble salts and other impurities in red mud. After removing impurities, the purity of red mud is improved, and its role in solidified soil is more stable and effective, and it can better participate in the reaction with carbide slag and other materials, thereby improving the quality and durability of solidified soil. Using red mud and carbide slag as the main components of the curing agent can improve the strength and durability of solidified soil compared to conventional cement curing agents.

[0060] It can be seen from Example 1 and Comparative Example 3 and Table 1 that the stable structure formed by the cooperation of clay, silty sand, bentonite and humus enables the solidified soil to maintain good performance during long-term use. This stable structure can resist the long-term effects of natural environmental factors and traffic loads, and reduce performance degradation caused by long-term stress and environmental influences.

[0061] Combining Examples 1-3 and Table 1, it can be seen that the alkali residue and soil material form a stable structure through a reasonable mix ratio, the soil material serves as a skeleton, and the alkali residue and fly ash cementitious products fill the pores, enhance the density, prevent the penetration of erosive substances, and improve durability. At the same time, the three work together to improve the strength of the solidified soil, the fly ash pozzolanic reaction increases the bonding force, the cementitious structure is tough, absorbs stress and reduces microcracks, can cope with long-term environmental impacts, maintain the strength and stability of the roadbed, extend the service life, reduce maintenance costs, and have significant long-term durability advantages.

[0062] It can be seen from Example 1 and Examples 4-13 and Table 1 that when cement and lime are compounded in a mass ratio of (1-2):1, the two can play a synergistic role of complementary advantages. The early strength and hydration products provided by cement provide a basis for subsequent reactions, while lime continues to play a role in the long-term process, further enhancing the strength and durability of the solidified soil through slow carbonization reaction and continuous stimulation of the activity of alkali slag. Red mud and carbide slag are mixed in a mass ratio of (1-3):1, and sodium lignin sulfonate is added, so that the two can fully play a synergistic role. The aluminum oxide in the red mud can react with the calcium hydroxide in the carbide slag to form hydrated calcium aluminate, and the silicon oxide can react with calcium hydroxide to form hydrated calcium silicate. These gelling substances are intertwined to form a solid network structure, which tightly bonds particles such as alkali slag, soil materials and fly ash together, significantly improving the strength and durability of the solidified soil.

[0063] It can be seen from Example 1 and Examples 14-15 and Table 1 that the appropriate water content can make the curing agent particles evenly dispersed and better dissolved in the alkali residue light solidified soil, accelerating the rate of chemical reaction. When the alkali residue light solidified soil does not contain a curing agent, a relatively low water content can avoid the soil material being too muddy due to excessive moisture, affecting the construction operation and the initial strength of the solidified soil. And the lower water content helps to reduce the volume change of the solidified soil after construction and during use.

[0064] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A light-weight solidified soil containing alkali residue, characterized in that: The components thereof include 40-50 parts of alkali residue, 30-40 parts of soil material and 10-30 parts of fly ash by weight.

2. The alkali residue lightweight solidified soil according to claim 1, characterized in that: Also includes 2-4 parts of curing agent.

3. The alkali residue lightweight solidified soil according to claim 2, characterized in that: The curing agent is a cement-lime composite curing agent, which is a mixture of silicate cement and lime in a mass ratio of (1-2):

1.

4. The alkali residue lightweight solidified soil according to claim 2, characterized in that: The curing agent is a red mud-carbide slag composite curing agent, and the preparation method of the red mud-carbide slag composite curing agent is as follows: The red mud is dried to reduce its water content to 20-30%, the dried red mud is crushed, and after crushing, it is sieved through a 100-mesh sieve, and then the sieved red mud is mixed with water in a mass ratio of 1: (3-5), stirred evenly, and then allowed to stand for 1-2 hours, and the upper alkaline aqueous solution is separated by filtration, and the separated red mud is repeatedly washed with water until the pH value of the red mud drops to 10-11; The carbide slag is dried to a moisture content of 10-20%, the dried carbide slag is ground, and after grinding, it is passed through an 80-mesh sieve; Red mud and carbide slag are mixed in a mass ratio of (1-3):1, and sodium lignin sulfonate is added in an amount of 1-5% of the total mass of the red mud and carbide slag during the mixing process to obtain a red mud-carbide slag composite curing agent.

5. The alkali residue lightweight solidified soil according to claim 1, characterized in that: The alkali slag with a particle size of more than 0.6 mm accounts for 20-30% of the total alkali slag, the alkali slag with a particle size of 0.1-0.6 mm accounts for 30-40% of the total alkali slag, and the alkali slag with a particle size of less than 0.1 mm accounts for 30-50% of the total alkali slag.

6. The alkali residue lightweight solidified soil according to claim 1, characterized in that: The soil material comprises 30-40% clay, 30-40% silty sand, 10-20% bentonite and 1-10% humus.

7. A method for constructing an alkali slag lightweight solidified soil roadbed as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Add water to the alkali slag lightweight solidified soil and stir it to make the water content in the alkali slag lightweight solidified soil 27-31%, and lay the alkali slag lightweight solidified soil at the predetermined position of the roadbed construction. Fill the sides of the laid alkali slag lightweight solidified soil with a thickness of more than 1m. The edge soil uses clay with a plasticity index of 10-20. After completion, compact and maintain the paving area to obtain the alkali slag lightweight solidified soil roadbed.

8. The alkali residue light solidified soil roadbed construction method according to claim 7, characterized in that: When the alkali residue lightweight solidified soil contains a curing agent, water is added and stirred to make the water content of the alkali residue lightweight solidified soil 29-31%. When the alkali residue lightweight solidified soil does not contain a curing agent, water is added and stirred to make the water content of the alkali residue lightweight solidified soil 27-29%.

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