A desulfurization ash foam lightweight soil and its preparation method

Abstract

The present application relates to the technical field of road construction and filling materials, and mainly to a desulfurization ash foam lightweight soil and its preparation method. It includes the following raw materials: (1) solid materials; the solid materials are calculated by weight, including: 50-60 parts of desulfurization ash, 30-40 parts of mineral powder, 10 parts of cement, and 1-5 parts of calcium chloride; (2) mixing water; the weight ratio of mixing water to solid materials is 0.5-0.7:1; (3) foam; the amount of foam is sufficient to make the volume of bubbles account for 40-70% of the total volume of the wet desulfurization ash foam lightweight soil composition obtained after mixing all the raw materials; the desulfurization ash is calcium desulfurization ash. The desulfurization ash can reach half of the amount of solid materials, which can realize large-scale recycling and reuse of desulfurization ash. The desulfurization ash foam lightweight soil also has good comprehensive performance, can effectively meet the use requirements of roadbed filling, and realize the comprehensive utilization of solid waste resources for roads.

Description

Technical Field

[0001] The present application relates to the technical field of road construction and filling materials, and mainly to a desulfurization ash foam lightweight soil and a preparation method thereof. Background Art

[0002] my country's clean energy, such as hydropower, wind power, solar power and nuclear power generation, is developing rapidly, but thermal power generation is still the main form of power generation in my country, which mainly relies on the burning of fossil fuels (coal, oil, gas, etc.) for power generation. In 2023 alone, my country's thermal power generation reached 6265.7 billion kWh. Among thermal power generation, coal-fired power generation is the main one, and the raw material coal generally contains sulfur. Therefore, the exhaust gas from coal-fired power plants generally needs to be desulfurized to reduce the emission of sulfur pollutants and reduce pollution. my country's coal-fired power generation is large in scale, so the scale of desulfurization products produced by the desulfurization process is also considerable. The problem of the disposal of desulfurization products has become an environmental problem that needs to be solved urgently.

[0003] Desulfurization ash in desulfurization products is mainly solid waste generated by desulfurization towers during flue gas desulfurization in coal-fired power plants. After years of exploration and research, a variety of mature desulfurization methods have been developed. According to the different desulfurizers used, desulfurization can generally be divided into calcium method, ammonia method, magnesium method, sodium method, seawater method and activated carbon method. According to the different water consumption in the process, there are wet method, semi-dry method and dry method, and the desulfurization products obtained are also of different types.

[0004] At present, there are few ways to utilize desulfurization ash. Except for a small amount used in the field of civil engineering, most of them are stored or landfilled, which not only occupies a large amount of land, but also easily causes secondary pollution to the environment. However, the dosage of desulfurization ash as a concrete admixture is generally not high. When used, simply increasing the dosage often leads to problems such as long concrete setting time and low hydration heat. When directly used in light soil, it is also prone to problems such as increased shrinkage and low strength, which makes it difficult to meet the requirements of roadbed filling. Therefore, it is necessary to propose a filling binder that can use a large amount of desulfurization ash and has stable performance, which is of great significance to the treatment of desulfurization ash and environmental protection in my country. Summary of the invention

[0005] The purpose of this application is to provide a desulfurization ash foam lightweight soil and a preparation method thereof, aiming to solve the problem of comprehensive utilization of existing desulfurization ash on roads, thereby providing a new way for large-scale disposal of desulfurization ash.

[0006] The technical solution of this application is as follows:

[0007] In a first aspect, the present application provides a desulfurization ash foam lightweight soil, which includes the following raw materials:

[0008] (1) Solid materials; the solid materials, calculated by weight, include:

[0009] 50-60 parts of desulfurized ash, 30-40 parts of mineral powder, 10 parts of cement, 1-5 parts of calcium chloride;

[0010] (2) mixing water; the weight ratio of the mixing water to the solid material is 0.5-0.7:1;

[0011] (3) foam; the amount of the foam is sufficient to make the volume of the bubbles account for 40-70% of the total volume of the wet desulfurization ash foam lightweight soil composition, and the wet desulfurization ash foam lightweight soil composition is obtained by mixing all the raw materials;

[0012] The desulfurization ash is calcium desulfurization ash.

[0013] The amount of desulfurization ash in the desulfurization ash foam lightweight soil provided in the present application can reach half of the amount of solid material, which can realize large-scale recovery and reuse of desulfurization ash. By using a larger amount of mineral powder, the coagulation properties of the desulfurization ash foam lightweight soil can also be controlled. The prepared desulfurization ash foam lightweight soil has good comprehensive properties, can effectively meet the use requirements of roadbed filling, and realize the comprehensive utilization of solid waste resources for roads.

[0014] Further, the foam is formed by the reaction of a chemical foaming agent to generate gas;

[0015] The raw materials of the foam include a chemical foaming agent and a foam stabilizer; the chemical foaming agent is a combination of aluminum sulfate and sodium bicarbonate;

[0016] The weight ratio of the chemical foaming agent to the cement in the solid material is 5-12:10;

[0017] The weight ratio of the foam stabilizer to the cement in the solid material is 0.3-0.9:10. By controlling the dosage of the chemical foaming agent and the foam stabilizer, the bubble structure and distribution degree formed are good, and it is not easy to form a connected defect structure. The foaming agent combination of aluminum sulfate and sodium bicarbonate can adjust the performance of desulfurized ash, so that the dosage of desulfurized ash can be maintained at a higher proportion.

[0018] Furthermore, the weight ratio of aluminum sulfate to sodium bicarbonate is 3-4: 1. Aluminum sulfate and sodium bicarbonate ensure the foaming effect through this ratio, and aluminum sulfate can be used as a reinforcing agent, which is beneficial to the stability of the performance of the desulfurized ash foam lightweight soil.

[0019] Furthermore, the foam stabilizer is calcium stearate.

[0020] Furthermore, the foam is formed by diluting a polymer surfactant type foaming agent with dilution water to form a foam liquid, and then introducing air into the foam liquid; the amount of the dilution water contained in the foam is not included in or calculated in the amount of the mixing water;

[0021] The polymer surfactant type foaming agent is a WJB01 type foaming agent, which includes: 38.4-57.6wt% of sodium lauryl polyoxyethylene ether sulfate, 15.2-22.8wt% of sodium α-olefin sulfonate, 4-6wt% of sodium dodecyl sulfate, 7.2-10.8wt% of lauryl amide propyl betaine-LAB, 12.8-19.2wt% of water, and 2.4-3.6wt% of triethanolamine.

[0022] Furthermore, the content of calcium sulfite in the calcium-process desulfurization ash does not exceed 10% of the total weight of the calcium-process desulfurization ash; and the particle size of the calcium-process desulfurization ash is 1-10 μm.

[0023] Furthermore, the mineral powder is blast furnace slag powder; and the cement is one of silicate cement and ordinary silicate cement.

[0024] Furthermore, the wet density of the wet desulfurized ash foam lightweight soil composition is 540-1000 kg / m 3 .

[0025] In a second aspect, the present application also provides a method for preparing the desulfurized ash foam lightweight soil as described above, which comprises the following steps:

[0026] Weigh the desulfurized ash, mineral powder, cement, aluminum sulfate, sodium bicarbonate, foam stabilizer, calcium chloride and mixing water for later use;

[0027] The desulfurized ash, mineral powder, cement, aluminum sulfate, foam stabilizer, calcium chloride and part of the mixing water are mixed to form a first gelling slurry;

[0028] According to the weight ratio of water to solid material, the sodium bicarbonate is added to the remaining mixed water to prepare a sodium bicarbonate solution;

[0029] The first gelling slurry and the sodium bicarbonate solution are mixed and allowed to stand for foaming to obtain a wet desulfurized ash foamed lightweight soil composition;

[0030] The desulfurized ash and mineral powder are mixed and ground, and then prepared into a first gelled slurry.

[0031] In a third aspect, the present application also provides a method for preparing the desulfurization ash foam lightweight soil as described above, which comprises the following steps:

[0032] Weigh the desulfurized ash, mineral powder, cement, WJB01 foaming agent, calcium chloride and mixing water for later use;

[0033] Firstly, the cement, mineral powder, desulfurized ash, calcium chloride and mixing water are mixed to form a second cementitious slurry;

[0034] The WJB01 type foaming agent is diluted with dilution water to obtain a foam liquid, and then air is introduced into the foam liquid to obtain foam;

[0035] The second cementitious slurry and the foam are stirred and mixed to obtain a wet desulfurization ash foam lightweight soil composition.

[0036] The preparation method provided in the present application is convenient and efficient, can be simply adjusted and applied to large-scale cast-in-place, and can produce desulfurized ash foam lightweight soil with uniformly distributed foam.

[0037] Beneficial effects: This application uses desulfurized ash as the main admixture of foamed lightweight soil, and the admixture amount can reach half of the solid dosage. The prepared desulfurized ash foamed lightweight soil can maintain good strength for a long time to achieve filling and compression resistance, and has good comprehensive performance. It can be used as a roadbed filling material or a filling material. In addition to alleviating the problem of scarce filling resources, it can effectively meet the requirements of filling, and can also realize the large-scale resource reuse of desulfurized ash. The comprehensive utilization of roads can reduce the cost of road filling, improve economic benefits, and be more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is the compressive strength of the desulfurization ash foam lightweight soil of Examples 1-5 of the present application. DETAILED DESCRIPTION

[0039] The present application provides a desulfurized ash foam lightweight soil and a preparation method thereof. To make the purpose, technical solution and effect of the present application clearer and more specific, the present application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0040] At present, in the field of civil engineering, the dosage of desulfurization ash is generally low, the efficiency of resource recycling is low, and the performance is difficult to guarantee. When the dosage is increased, the performance is difficult to guarantee to meet the filling requirements.

[0041] To solve this problem, the present application provides a desulfurization ash foam lightweight soil, which includes the following raw materials:

[0042] (1) Solid materials; solid materials are calculated by weight and include:

[0043] 50-60 parts of desulfurized ash, 30-40 parts of mineral powder, 10 parts of cement;

[0044] (2) Mixing water; the weight ratio of mixing water to solid material is 0.5-0.7:1;

[0045] (3) Foam; the amount of foam is sufficient to make the volume of bubbles account for 40-70% of the total volume of the wet desulfurized ash foam lightweight soil composition obtained after mixing all the raw materials;

[0046] The desulfurization ash is calcium desulfurization ash.

[0047] In the present application, the weight ratio of mixing water to solid materials is the water-solid ratio. A large proportion of desulfurized ash is mixed into the lightweight soil of the present application, and the water demand of desulfurized ash is large. The water-solid ratio is maintained at 0.5-0.7:1 to ensure fluidity during pouring, which is conducive to large-scale cast-in-place. Among them, the amount of foam is sufficient to make the volume of bubbles account for the proportion of the total volume of the wet desulfurized ash foam lightweight soil composition obtained after mixing all the raw materials, which is expressed as the bubble rate. The bubble rate will affect the wet density and compressive strength of the desulfurized ash foam lightweight soil. Too high a bubble rate will easily lead to the strength of the lightweight soil being difficult to meet the use, so the bubbles need to be controlled at 40-70%.

[0048] This application uses desulfurized ash as the main admixture of foamed lightweight soil, and the admixture amount can reach half of the solid dosage. The prepared desulfurized ash foamed lightweight soil can maintain good strength for a long time when used as a road filling material to achieve filling and compression resistance, and has good comprehensive performance. It can be used as a roadbed filling material or a filling material to meet the use requirements. In addition to alleviating the problem of scarce filling resources, it can also realize large-scale resource reuse of desulfurized ash and reduce road filling costs, improve economic benefits and be more environmentally friendly.

[0049] There are many different desulfurization processes in the actual desulfurization process. The components of desulfurization ash obtained by using different desulfurizers are also different, and the utilization methods are not exactly the same. Not all desulfurization ash can be well applied to the field of civil engineering. For example, the desulfurization ash obtained by sodium desulfurization has a high sodium salt content, and the weather resistance and service life when used in concrete are low. Therefore, the desulfurization ash of this application is preferably calcium desulfurization ash, which has sufficient calcium content and can participate in hydration reaction for condensation.

[0050] Furthermore, the content of calcium sulfite in the calcium-process desulfurization ash does not exceed 10% of the total weight of the calcium-process desulfurization ash. The main components of the calcium-process desulfurization ash are calcium components such as calcium carbonate, calcium sulfite, calcium sulfate, calcium hydroxide and free calcium oxide. The inventors found that if the content of calcium sulfite is high, it will prolong the coagulation time of the desulfurization ash foam lightweight soil, which is not conducive to engineering applications and also limits the performance of the desulfurization ash. The embodiment of the present application uses calcium-process desulfurization ash with a calcium sulfite content not exceeding 10% of the total weight of the calcium-process desulfurization ash, which makes it easier to adjust the performance of the desulfurization ash foam lightweight soil and the performance is more stable.

[0051] Furthermore, the particle size of calcium desulfurization ash is 1-10 μm. The desulfurizer in the calcium desulfurization process is mainly lime, and the particle size of lime has a direct impact on the desulfurization effect. Generally speaking, the smaller the particle size of lime, the larger the specific surface area, and the more fully it can play the absorption role. The desulfurization ash collected after desulfurization is also smaller than the particle size of general industrial solid waste. However, in this application, due to the large amount of desulfurization ash, the properties of desulfurization ash have a more obvious effect on lightweight soil, and the fineness of desulfurization ash needs to be controlled. Generally, the activity of desulfurization ash with larger particle size is difficult to be stimulated, and the smaller the particle size, the higher the specific surface area, and the more obvious the activity effect, but the degree of increase in specific surface area as the particle size continues to decrease is also limited, and the cost is also high. This application controls the particle size of calcium desulfurization ash at 1-10 μm, controls the cost while ensuring the activity of desulfurization ash, and can also improve the compactness and reduce the porosity in the hydration reaction stage, and the cementation effect of lightweight soil is also better. In addition, by controlling the particle size of calcium desulfurization ash, the water requirement of desulfurization ash can be controlled and reduced, so that the water-solid ratio of lightweight soil can be controlled when a large amount is used, which is also conducive to maintaining the compressive strength of lightweight soil after hardening. Among them, calcium desulfurization ash can be ground with mineral powder to the required particle size and then prepared.

[0052] In the present application, desulfurized ash, cement and mineral powder are mixed to obtain a mixture, which is then mixed with water to form a cementitious slurry for hardening. The cementitious slurry can be prepared by mixing lightweight components to prepare a wet desulfurized ash foam lightweight soil composition, and the wet desulfurized ash foam lightweight soil composition is hardened to obtain desulfurized ash foam lightweight soil. The specific mixing method can be selected from one of the following three methods, including: (1) the surfactant foaming agent is diluted and foamed by dilution water to obtain foam, the mixture is prepared into a cementitious slurry by mixing water, and then mixed with the foam to form a wet desulfurized ash foam lightweight soil composition; (2) the self-foaming foaming agent is mixed with the mixture, and then the mixture is prepared into a cementitious slurry by adding mixing water, and the foaming agent foams therein to form a wet desulfurized ash foam lightweight soil composition; (3) the mixture is prepared into a cementitious slurry by mixing water, and then mixed with rubber and plastic micropowder to form a wet desulfurized ash foam lightweight soil composition; the rubber and plastic micropowder can be waste foamed PU particles, EPS particles and rubber particles.

[0053] In the present application, the desulfurized ash foam lightweight soil can be prepared by the first method, which has better economic benefits and higher cost performance, and is conducive to market promotion and application. Among them, the added foam is formed by diluting a polymer surfactant type foaming agent with dilution water to form a foam liquid, and then passing air into the foam liquid; the amount of dilution water contained in the foam is not included or calculated in the amount of mixing water.

[0054] Among them, the polymer surfactant type foaming agent is a WJB01 type foaming agent, including: sodium lauryl polyoxyethylene ether sulfate 38.4-57.6wt%, sodium α-olefin sulfonate 15.2-22.8wt%, sodium dodecyl sulfate 4-6wt%, lauryl amide propyl betaine-LAB 7.2-10.8wt%, and water 15.2-22.8wt%. The wt% is based on the weight of the WJB01 type foaming agent. The sum of the amounts of all components is equal to 100wt%. The water demand of desulfurized ash is relatively high. Considering that it may affect the moisture of the foam and affect the stability of the foam after mixing with the foam in a larger amount, the foaming effect and foam stability can be improved by the dosage ratio of the foaming agent of the present application, and no additional foam stabilizer is required for use. The foaming effect of the provided foaming agent is good, and the formed foam can also be stably present as a light component in the gel slurry after mixing.

[0055] Further, the WJB01 type foaming agent may also include: sodium lauryl polyoxyethylene ether sulfate 38.4-57.6wt%, sodium α-olefin sulfonate 15.2-22.8wt%, sodium dodecyl sulfate 4-6wt%, lauryl amide propyl betaine-LAB 7.2-10.8wt%, water 12.8-19.2wt%, triethanolamine 2.4-3.6wt%. The wt% is based on the weight of the WJB01 type foaming agent. The amount of all components added together equals 100wt%. In the present application, WJB01 foaming agent can also be used by adding triethanolamine and replacing part of the water. It can maintain the foaming effect in some construction conditions with relatively low temperature (≤10°C), improve the low-temperature early strength performance of foamed lightweight soil, and at the same time improve the fluidity of lightweight soil, reduce the water-solid ratio required for mixing, and can improve the uniform distribution of foam while continuing to maintain a water-solid ratio of 0.5-0.7:1. It can also maintain good compressive strength at the same foam ratio.

[0056] The desulfurized ash foam lightweight soil of the present application can also be prepared by the second method, and has better comprehensive performance. The self-foaming foaming agent can generate gas by reacting with a chemical foaming agent to form foam.

[0057] Furthermore, the raw materials of the foam include a chemical foaming agent and a foam stabilizer; the foaming agent is a combination of aluminum sulfate and sodium bicarbonate. In the present application, aluminum sulfate and sodium bicarbonate as a combination of chemical foaming agents can be incorporated into solid materials, and carbon dioxide generated by the double hydrolysis reaction of aluminum sulfate and sodium bicarbonate is used as a light component source to self-foam in the gel slurry to form foamed lightweight soil, which is convenient and efficient, and can also save the process of mixing with foam, which is conducive to pouring construction.

[0058] Furthermore, the weight ratio of the chemical foaming agent to the cement in the solid material is 5-12: 10. The average pore size and density of the bubbles formed during foaming generally increase with the increase in the amount of the chemical foaming agent, but the increase in the average pore size of the bubbles increases the risk of forming interconnected pores and is prone to forming defects, so the amount of the chemical foaming agent in the solid material is 5-12 parts, which is conducive to ensuring sufficient lightweight components in the lightweight soil and maintaining the uniform distribution of the foam in the lightweight soil.

[0059] Furthermore, the content of free calcium oxide in the calcium desulfurization ash accounts for 4% of the total weight of the calcium desulfurization ash, and the content of calcium hydroxide accounts for 10% of the total weight of the calcium desulfurization ash. The present application uses calcium desulfurization ash with suitable free calcium oxide and calcium hydroxide content, and under the action of the foaming agent combination and dosage of aluminum sulfate and sodium bicarbonate, the performance stability of desulfurization ash foam lightweight soil can be further improved. In the provided desulfurization ash foam lightweight soil, if the content of calcium oxide and calcium hydroxide is too high, it is easy to affect the cementation performance of the foam lightweight soil, and the coagulation process has a greater impact on the volume of the lightweight soil, increasing the risk of cracks. The carbon dioxide generated by foaming in the present application consumes part of the calcium hydroxide while forming a bubble structure, and the calcium oxide component therein will also react with water to generate calcium hydroxide for supplementation. After being consumed, the free calcium oxide and calcium hydroxide can maintain a suitable content in the lightweight soil, and the purpose of regulating the calcium component in the lightweight soil is achieved through the interaction between them. After the overall calcium component is controlled, it participates in the hydration reaction, which is conducive to improving the performance stability of the lightweight soil. Since desulfurization ash is generally disposed of by stockpiling, through the dosage ratio of this application, the remaining calcium hydroxide can also work together with the intermediate product aluminum hydroxide generated by the reaction of aluminum sulfate and sodium bicarbonate to reduce the adverse cementing components that may be mixed in the stockpiling (some acidic substances in the atmosphere or soil), and play a stimulating role while ensuring an alkaline environment, promoting the hydration reaction. Without the need for additional stimulants, the potential activity of blast furnace slag powder can be stimulated, so that the dosage of desulfurization ash and mineral powder in this application is guaranteed, which is also conducive to the stabilization of the application performance of the desulfurization ash, and the early strength and overall coagulation properties of the lightweight soil produced can be improved.

[0060] Furthermore, the weight ratio of aluminum sulfate to sodium bicarbonate is 3-4:1. In the present application, in the actual working condition of long-term use of roadbed filling, the overall strength of the desulfurization ash foam lightweight soil is more susceptible to weathering erosion, and sodium components are used in the foaming agent. In addition to ensuring the foaming process, the present application controls the ratio of aluminum sulfate and sodium bicarbonate. In addition, it can also avoid incomplete reaction of sodium bicarbonate, which may lead to the formation of sodium carbonate or the subsequent formation of excess sodium salts, and is also beneficial to reduce the weathering effect on the desulfurization ash foam lightweight soil. Moreover, since the particle size of the desulfurization ash used is small, aluminum sulfate can also be evenly distributed in the lightweight soil. The remaining aluminum sulfate can also participate in the hydration reaction as a reinforcing agent for the desulfurization ash foam lightweight soil, which can improve the overall filling effect of the hydration reaction stage, and is also beneficial to improve the waterproofness and impermeability and further improve the weather resistance. Among them, the remaining aluminum sulfate can also form some aluminate minerals when participating in the hydration reaction, and can also react with the calcium sulfite in the desulfurization ash. The porous structure formed by the foamed lightweight soil after stabilization is also conducive to the contact and oxidation of calcium sulfite with air to form calcium sulfate with more stable performance, thereby improving the coordination effect of desulfurization ash and cementitious materials and promoting the degree of calcium sulfite participating in the hydration reaction, which is conducive to slowing down the strength shrinkage that may be caused by calcium sulfite. At the same time, under the action of mineral powder, the strength improvement of the lightweight soil during the coagulation process can be maintained.

[0061] Furthermore, the weight ratio of the foam stabilizer to the cement in the solid material is 0.3-0.9:10. In the present application, by adding the foam stabilizer to act on the chemical foaming process, it is possible to promote foaming and reduce the surface tension of the bubbles, which is conducive to forming an average and evenly distributed microporous structure, so as to avoid the formation of excessively large pores that are easy to collapse and affect the local properties of the desulfurized ash foam lightweight soil. In addition, due to the obvious activity of the binder, the foam stabilizer can act on the foaming process of the self-foaming, affecting the interfacial properties of the bubbles. The continued increase in the dosage will increase the risk of a large number of connected pores formed by the bubbles therein. Therefore, the amount of the foam stabilizer in the solid material is controlled at 0.3-0.9 parts, which is conducive to reducing the shrinkage rate of the desulfurized ash foam lightweight soil.

[0062] Furthermore, the foam stabilizer is calcium stearate. In the present application, the foam stabilizer can also play a certain hydrophobic role by using calcium stearate, reduce the freeze-thaw cycle of water, and improve the weathering resistance of the desulfurized ash foam lightweight soil. Calcium stearate can also adjust the coagulation time of lightweight soil. In the early stage of coagulation, calcium stearate can accelerate the coagulation speed of lightweight soil. Through the uniform distribution of bubbles, the effect is also better, and the coagulation time of large-volume desulfurized ash can be shortened. In the later stage of coagulation, calcium stearate can appropriately delay the coagulation speed, and coagulate under the later strength enhancement effect of blast furnace slag powder, which is beneficial to increase the strength of lightweight soil while coping with volume changes, reducing the degree of shrinkage, and improving the crack resistance of lightweight soil.

[0063] In the form of self-foaming in the present application, the combination of calcium stearate and chemical foaming agent can improve the stability of the microporous structure formed by bubbles. The fluid desulfurization ash foam lightweight soil composition is generally no longer adjusted after the leveling is stable and the foaming begins, so as not to affect the stability of the foam or cause it to escape. The self-foaming form is specifically manifested in that the bubbles formed by foaming at a fixed point continue to increase, and there is a certain risk of interconnection. The chemical foaming agent combination of the present application foams through carbon dioxide and interacts with the calcium component in the desulfurization ash to a certain extent, which can consume part of the excess carbon dioxide, improve the stability of the bubbles, and thus reduce the risk of forming interconnected holes, and can improve the uniformity of the size of the bubbles. At the same time, under the action of calcium stearate and aluminum sulfate near the foaming site, the hydration reaction around the bubbles is accelerated, which can accelerate the microporous structure formed by stabilizing the bubbles, ensure the lightweight effect of the bubbles, and is beneficial to the strength maintenance of the lightweight soil, and the overall performance difference is also lower.

[0064] Generally speaking, a higher water consumption is required for foam mixing to ensure the overall foam distribution effect, which can easily affect the strength. The performance of the desulfurization ash with a large amount of addition in this application is more sensitive to being affected. The desulfurization ash foam lightweight soil prepared by the foaming agent combination of this application has a lower water-to-solid ratio than general foam mixing pre-foaming, and the volume stability is more guaranteed, the strength is higher, and the weight is more reliable.

[0065] Furthermore, cement is one of silicate cement and ordinary silicate cement. In lightweight soil used for filling or pouring, the cost of cement used therein accounts for a large proportion, and the production of cement undergoes "two grindings and one burning", which consumes a lot of energy. This application uses a large proportion of desulfurized ash to provide a certain alkaline environment in the hydration reaction stage to stimulate it. Under the action of cement and desulfurized ash, mineral powder can also participate in good cementation. Therefore, maintaining the amount of cement at 10 parts can ensure a good cementation effect, while reducing costs and energy consumption.

[0066] Furthermore, the mineral powder is blast furnace slag powder. Blast furnace slag powder has potential activity, and can be secondary hydrated by the hydration products of cement during the coagulation process of lightweight soil, has a strength enhancement effect, and can improve the later strength of foam lightweight soil. In addition, the cement dosage of the present application is relatively low, the overall dosage of cementitious materials is compatible with desulfurization ash, and no other stimulant is added, and the dosage of blast furnace slag powder should not be further increased. The foam lightweight soil provided in the present application is mainly used for filling, and the early strength and overall strength requirements are relatively lower than those of structural concrete. Therefore, the dosage of blast furnace slag powder can be slightly higher than that of general structural concrete, and the dosage can be maintained at 30-40 parts. This dosage can also provide sufficient later enhancement effects, can slow down the degree of shrinkage of higher dosage desulfurization ash, and has more advantages than the application performance in structural concrete. In addition, the calcium sulfite component in the calcium-based desulfurization ash also has a more obvious stimulating effect on the cementitious system mixed with mineral powder and cement, which is beneficial to the overall bonding performance and strength of the desulfurization ash foam lightweight soil at this dosage ratio to effectively meet the filling requirements.

[0067] Furthermore, the wet density of the wet desulfurized ash foam lightweight soil composition is 540-1000 kg / m 3 The desulfurization ash foam lightweight soil provided in this application is a controllable low-strength material. The strength can be controlled by adjusting the component dosage, foaming degree and water-solid ratio. By controlling the wet density within a certain range, the performance of the desulfurization ash foam lightweight soil can be ensured to be relatively stable, and the workability during preparation can also meet the fluidity requirements of large-scale cast-in-place. Among them, according to the wet density of the desulfurization ash foam lightweight soil from 540 kg / m 3 Up to 1000kg / m 3 The weight ratio of cement, mineral powder and desulfurization ash can be transitioned from 1:4:5 to 1:3:6. The specific material ratio can depend on the design strength and wet density. When the wet density needs to be increased, the strength requirement of the desulfurization ash foam lightweight soil is also reduced. The amount of desulfurization ash can be appropriately increased and the amount of mineral powder can be reduced. The water demand increases, and it is easier to meet the wet density requirements.

[0068] Furthermore, the solid material may also include 1-5 parts of calcium chloride. At this time, the solid material is calculated by weight and includes the following raw materials: 50-60 parts of desulfurized ash, 30-40 parts of mineral powder, 10 parts of cement, and 1-5 parts of calcium chloride. In the present application, in order to improve the strength, especially the early strength, calcium chloride accounting for 1-5 parts of the total amount of solid materials can be added, which can improve the coagulation performance of the desulfurized ash foamed lightweight soil. Among them, considering that calcium chloride may react with sodium bicarbonate in the chemical foaming agent, although carbon dioxide will also be generated to produce bubbles, the efficiency is relatively low. Therefore, the amount of calcium chloride is maintained at 1-5 parts to avoid a significant impact on the bubble rate of the chemical foaming agent. The addition of calcium chloride can also play a certain role in accelerating coagulation, which is conducive to the stable distribution of bubbles.

[0069] The foam hydraulic cementitious material provided in the present application has good compressive strength after hardening, and the performance of the desulfurization ash foam lightweight soil in the present application has been adjusted. Through the coordination between them, the performance can be kept stable and the risk of subsidence is low, so it can be effectively used as a road construction and filling material.

[0070] When a chemical foaming agent is used, the present application also provides a method for preparing the desulfurized ash foamed lightweight soil as described above, which comprises the following steps:

[0071] Weigh desulfurized ash, mineral powder, cement, aluminum sulfate, sodium bicarbonate, foam stabilizer, calcium chloride and mixing water for later use;

[0072] The desulfurized ash, mineral powder, cement, aluminum sulfate, foam stabilizer, calcium chloride and part of the mixing water are mixed evenly to form a first gelling slurry;

[0073] According to the weight ratio of water to solid material, sodium bicarbonate is added to the remaining mixed water to prepare a sodium bicarbonate solution;

[0074] The first cementitious slurry and the sodium bicarbonate solution are mixed and allowed to stand for foaming to obtain a wet desulfurized ash foamed lightweight soil composition.

[0075] In the present application, aluminum sulfate and sodium bicarbonate have good reaction performance. If they are mixed too early or poured untimely, part of the first generated carbon dioxide will easily escape, resulting in uneven bubble distribution, thus affecting the overall performance of the desulfurization ash foam lightweight soil. Therefore, aluminum sulfate and sodium bicarbonate solutions need to be prepared separately and can be mixed before pouring at the construction site. Specifically, after aluminum sulfate is prepared into the first cementitious slurry, it can be first transferred to the construction site by pumping or transportation, and then the sodium bicarbonate solution can be prepared at the construction site, and then the first cementitious slurry can be pumped for the second time by a slurry pump. At the feed port of the slurry pump, three sodium bicarbonate solution inlet pipelines can be set up, and the sodium bicarbonate solution can be pumped synchronously using an adjustable metering pump. The sodium bicarbonate solution and the first cementitious slurry are evenly mixed by high-speed stirring of the centrifugal blades of the slurry pump, and the mixed slurry is pumped to the project site. After 20-30 minutes of static foaming process of double hydrolysis reaction, the volume of the mixed slurry automatically expands, thereby forming a wet desulfurization ash foam lightweight soil composition, and then the desulfurization ash foam lightweight soil is obtained through condensation.

[0076] Furthermore, the desulfurization ash and the mineral powder are mixed and ground, and then prepared into the first gelled slurry. Due to the characteristics of the calcium desulfurization process, the desulfurizer is sprayed into the desulfurization tower and contacts with sulfur dioxide to react. At this time, the outer layer of the desulfurizer will generally seal the inside after the reaction, so the desulfurization ash actually collected will have different properties inside and outside. In the present application, by mixing and grinding the desulfurization ash and the mineral powder, in addition to improving the mixing efficiency and stimulating the activity, the desulfurization ash can also be broken by grinding, and the desulfurization agent inside can be released. In addition to the higher activity, the degree of interaction with the foaming agent and bubbles is also higher, and the coagulation performance and use performance of the lightweight soil can be more stable, and the weather resistance can also be improved.

[0077] When a polymer surfactant foaming agent is used for foaming, the present application also provides a method for preparing the desulfurized ash foamed lightweight soil as described above, which comprises the following steps:

[0078] Weigh desulfurized ash, mineral powder, cement, WJB01 foaming agent, calcium chloride and mixing water for later use;

[0079] Firstly, cement, mineral powder, desulfurized ash, calcium chloride and mixing water are mixed to form a second cementitious slurry;

[0080] The WJB01 foaming agent is diluted with diluting water to obtain a foam liquid, and then air is introduced into the foam liquid to obtain foam;

[0081] The second cementitious slurry and the foam are stirred and mixed to obtain a wet desulfurization ash foam lightweight soil composition.

[0082] Among them, the weight ratio of WJB01 foaming agent and dilution water is 1:120-1:200. When the temperature is lower in winter, the proportion of dilution water is low, generally 1:120; when the temperature is higher in summer, the amount of dilution water is increased, generally 1:200.

[0083] Since the prepared wet desulfurization ash foam lightweight soil composition has the characteristics of self-hardening, self-leveling, high fluidity and easy construction, in actual working conditions, preparation and construction can be carried out simultaneously. Specifically, after preparing the second cementitious slurry, a second cementitious slurry flow can be formed by pumping, and after preparing the foam, a foam flow can be formed by pumping, and then the cementitious slurry flow and the foam flow are mixed in a static mixer to form a wet desulfurization ash foam lightweight soil composition, and then directly pumped to the project site for filling construction. The overall construction process is fast and efficient, and rapid filling can be achieved. Among them, the foaming degree of the foam liquid can be controlled according to the actual situation, and the flow ratio between the foam flow and the second cementitious slurry flow can be controlled for mixing, so that the desulfurization ash foam lightweight soil composition directly pumped to the project site can meet the bubble rate requirements required by the actual situation.

[0084] In addition, in the desulfurization ash foamed lightweight soil prepared by WJB01 type foaming agent, the degree of interaction between solid materials and bubbles is lower than that of chemical foaming agent, but desulfurization ash and mineral powder can also be ground and then prepared, and the pouring performance can also be improved.

[0085] The preparation method provided in the present application is convenient and efficient, can be simply adjusted and applied to large-scale cast-in-place, and can produce desulfurized ash foam lightweight soil with uniformly distributed and stable foam.

[0086] The invention is further described below by means of specific examples.

[0087] Example 1

[0088] The desulfurized ash foamed lightweight soil of Example 1 comprises the following raw materials:

[0089] (1) Solid materials; solid materials are calculated by weight and include:

[0090] 50 parts of desulfurized ash, 40 parts of mineral powder, 10 parts of cement, 9 parts of aluminum sulfate, 3 parts of sodium bicarbonate, 0.6 parts of foam stabilizer, and 2 parts of calcium chloride;

[0091] (2) Mixing water: The weight ratio of mixing water to solid material is 0.6:1.

[0092] The desulfurization ash is calcium desulfurization ash with a particle size of 3μm. The content of calcium sulfite in the calcium desulfurization ash accounts for 8% of the total weight of the calcium desulfurization ash, the content of free calcium oxide accounts for 4% of the total weight of the calcium desulfurization ash, and the content of calcium hydroxide accounts for 10% of the total weight of the calcium desulfurization ash; the mineral powder is blast furnace slag powder; and the foam stabilizer is calcium stearate.

[0093] The method for preparing the desulfurized ash foam lightweight soil of Example 1 comprises the following steps:

[0094] Weigh calcium desulfurization ash, blast furnace slag powder, cement, aluminum sulfate, sodium bicarbonate, foam stabilizer, calcium chloride and mixing water for later use;

[0095] The calcium desulfurization ash, blast furnace slag powder, cement, aluminum sulfate, foam stabilizer, calcium chloride and part of the mixing water are mixed evenly to form a first gelling slurry;

[0096] According to the weight ratio of water to solid material, sodium bicarbonate is added to the remaining mixed water to prepare a sodium bicarbonate solution;

[0097] The first gelling slurry and the sodium bicarbonate solution are mixed evenly and allowed to stand for foaming to obtain the wet desulfurization ash foam lightweight soil composition of Example 1.

[0098] Before preparing the first gelled slurry, the calcium desulfurization ash and blast furnace slag powder are mixed and ground.

[0099] The desulfurized ash foam lightweight soil composition prepared in Example 1 has a bubble rate of 65% after standing and foaming, a fluidity of 160 mm, and a wet density of 610 kg / m 3 After standard curing, the strength reaches 0.87MPa at 7d and 1.17MPa at 28d.

[0100] Example 2

[0101] The desulfurized ash foamed lightweight soil of Example 2 comprises the following raw materials:

[0102] (1) Solid materials; solid materials are calculated by weight and include:

[0103] 50 parts of desulfurized ash, 40 parts of mineral powder, 10 parts of cement, 8 parts of aluminum sulfate, 2.5 parts of sodium bicarbonate, 0.6 parts of foam stabilizer, and 2 parts of calcium chloride;

[0104] (2) Mixing water: The weight ratio of mixing water to solid material is 0.55:1.

[0105] The desulfurization ash is calcium desulfurization ash with a particle size of 3μm. The content of calcium sulfite in the calcium desulfurization ash accounts for 8% of the total weight of the calcium desulfurization ash, the content of free calcium oxide accounts for 4% of the total weight of the calcium desulfurization ash, and the content of calcium hydroxide accounts for 10% of the total weight of the calcium desulfurization ash; the mineral powder is blast furnace slag powder; and the foam stabilizer is calcium stearate.

[0106] The wet desulfurization ash foam lightweight soil composition of Example 2 was prepared by the same preparation method as Example 1.

[0107] The desulfurized ash foam lightweight soil composition prepared in Example 2 has a bubble rate of 56% after standing and foaming, a fluidity of 163 mm, and a wet density of 760 kg / m 3 After standard curing, the strength reaches 1.60 MPa at 7 days and 1.92 MPa at 28 days.

[0108] Example 3

[0109] The desulfurized ash foamed lightweight soil of Example 3 comprises the following raw materials:

[0110] (1) Solid materials; solid materials are calculated by weight and include:

[0111] 50 parts of desulfurized ash, 40 parts of mineral powder, 10 parts of cement, 8 parts of aluminum sulfate, 2 parts of sodium bicarbonate, 0.6 parts of foam stabilizer, and 2 parts of calcium chloride;

[0112] (2) Mixing water: The weight ratio of mixing water to solid material is 0.5:1.

[0113] The desulfurization ash is calcium desulfurization ash with a particle size of 3μm. The content of calcium sulfite in the calcium desulfurization ash accounts for 8% of the total weight of the calcium desulfurization ash, the content of free calcium oxide accounts for 4% of the total weight of the calcium desulfurization ash, and the content of calcium hydroxide accounts for 10% of the total weight of the calcium desulfurization ash; the mineral powder is blast furnace slag powder; and the foam stabilizer is calcium stearate.

[0114] The wet desulfurization ash foam lightweight soil composition of Example 3 was prepared by the same preparation method as Example 1.

[0115] The desulfurized ash foamed lightweight soil composition prepared in Example 3 has a bubble rate of 51% after standing and foaming, a fluidity of 160 mm, and a wet density of 840 kg / m 3 After standard curing, the strength reaches 2.00 MPa at 7 days and 2.20 MPa at 28 days.

[0116] Example 4

[0117] The desulfurized ash foamed lightweight soil of Example 4 comprises the following raw materials:

[0118] (1) Solid materials; solid materials are calculated by weight and include:

[0119] 50 parts of desulfurized ash, 40 parts of mineral powder, 10 parts of cement, 7 parts of aluminum sulfate, 2 parts of sodium bicarbonate, 0.6 parts of foam stabilizer, and 3 parts of calcium chloride;

[0120] (2) Mixing water: The weight ratio of mixing water to solid material is 0.5:1.

[0121] The desulfurization ash is calcium desulfurization ash with a particle size of 3μm. The content of calcium sulfite in the calcium desulfurization ash accounts for 8% of the total weight of the calcium desulfurization ash, the content of free calcium oxide accounts for 4% of the total weight of the calcium desulfurization ash, and the content of calcium hydroxide accounts for 10% of the total weight of the calcium desulfurization ash; the mineral powder is blast furnace slag powder; and the foam stabilizer is calcium stearate.

[0122] The wet desulfurization ash foam lightweight soil composition of Example 4 was prepared by the same preparation method as Example 1.

[0123] The desulfurized ash foam lightweight soil composition prepared in Example 4 has a bubble rate of 48% after standing and foaming, a fluidity of 165 mm, and a wet density of 890 kg / m 3 After standard curing, the strength reaches 2.07MPa at 7d and 2.50MPa at 28d.

[0124] Example 5

[0125] The desulfurized ash foamed lightweight soil of Example 5 comprises the following raw materials:

[0126] (1) Solid materials; solid materials are calculated by weight and include:

[0127] 50 parts of desulfurized ash, 40 parts of mineral powder, 10 parts of cement, 6 parts of aluminum sulfate, 2 parts of sodium bicarbonate, 0.6 parts of foam stabilizer, and 4 parts of calcium chloride;

[0128] (2) Mixing water: The weight ratio of mixing water to solid material is 0.5:1.

[0129] The desulfurization ash is calcium desulfurization ash with a particle size of 3μm. The content of calcium sulfite in the calcium desulfurization ash accounts for 8% of the total weight of the calcium desulfurization ash, the content of free calcium oxide accounts for 4% of the total weight of the calcium desulfurization ash, and the content of calcium hydroxide accounts for 10% of the total weight of the calcium desulfurization ash; the mineral powder is blast furnace slag powder; and the foam stabilizer is calcium stearate.

[0130] The wet desulfurization ash foam lightweight soil composition of Example 5 was prepared by the same preparation method as Example 1.

[0131] The desulfurized ash foamed lightweight soil composition prepared in Example 5 has a bubble rate of 45% after standing and foaming, a fluidity of 165 mm, and a wet density of 950 kg / m3 After standard curing, the strength reaches 2.95MPa at 7d and 3.45MPa at 28d.

[0132] The strength of desulfurized ash foam lightweight soil with different wet density in Example 1-5 is as follows Figure 1 As shown in the figure, with the increase of wet density, the compressive strength increases, and the compressive strength achieved can also meet the use requirements of "Highway Subgrade Design Code" JTGD30-2015.

[0133] Example 6

[0134] The desulfurized ash foamed lightweight soil of Example 6 comprises the following raw materials:

[0135] (1) Solid materials; solid materials are calculated by weight and include:

[0136] 50 parts of desulfurized ash, 40 parts of mineral powder, 10 parts of cement, 4 parts of calcium chloride;

[0137] (2) Mixing water: The weight ratio of mixing water to solid material is 0.5:1.

[0138] The desulfurization ash is calcium desulfurization ash with a particle size of 3μm. The content of calcium sulfite in the calcium desulfurization ash accounts for 8% of the total weight of the calcium desulfurization ash, the content of free calcium oxide accounts for 4% of the total weight of the calcium desulfurization ash, and the content of calcium hydroxide accounts for 10% of the total weight of the calcium desulfurization ash; the mineral powder is blast furnace slag powder.

[0139] The foam is obtained by foaming a WJB01 type foaming agent, and the composition of the WJB01 type foaming agent is: 48% sodium lauryl polyoxyethylene ether sulfate, 19% sodium α-olefin sulfonate, 5% sodium dodecyl sulfate, 9% lauryl amide propyl betaine-LAB, 16% water, and 3wt% triethanolamine.

[0140] The method for preparing the desulfurized ash foam lightweight soil of Example 6 comprises the following steps:

[0141] Weigh desulfurized ash, mineral powder, cement, WJB01 foaming agent, calcium chloride and mixing water for later use;

[0142] Firstly, cement, mineral powder, desulfurized ash, calcium chloride and mixing water are mixed to form a second cementitious slurry;

[0143] The WJB01 foaming agent is diluted with diluting water to obtain a foam liquid, and then air is introduced into the foam liquid to obtain foam;

[0144] The second cementitious slurry and the foam are stirred and mixed to obtain the wet desulfurization ash foam lightweight soil composition of Example 6.

[0145] The weight ratio of WJB01 foaming agent to dilution water is 1:160. After weighing WJB01 foaming agent, dilution water is added in proportion to obtain foam liquid, the prepared foam liquid is injected into the foaming device, compressed air with an output pressure of 1.8 atm is passed into the foam liquid to allow the foam liquid to fully foam to form foam, and immediately after obtaining the foam (generally no more than 10 minutes), the foam is added to the second cementitious slurry and continued to stir and mix for 10 minutes (50r / min) to obtain the wet desulfurized ash foam lightweight soil composition of Example 6.

[0146] The proportion of foam added to the wet desulfurized ash foam lightweight soil composition obtained in Example 6 is controlled according to the bubble rate. The desulfurized ash foam lightweight soil composition obtained in Example 6 has a bubble rate of 45% after mixing with foam, a fluidity of 167 mm, and a wet density of 956 kg / m 3 After standard curing, the strength reaches 2.93 MPa at 7 days and 3.40 MPa at 28 days.

[0147] The desulfurization ash foam lightweight soil provided in the present application can realize the resource recycling of large-scale desulfurization ash, effectively meet the use requirements of roadbed filling, can cope with the disposal of desulfurization ash solid waste and carry out comprehensive utilization of roads, reduce road construction costs, and is of great significance to the treatment of desulfurization ash and environmental protection in my country, and can also alleviate the problem of scarce filling resources.

[0148] It should be understood that the application of the present application is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made according to the above description, and all these improvements and changes should fall within the scope of protection of the present application.

Claims

1. A desulfurization ash foam lightweight soil, characterized in that: Including the following ingredients: (1) Solid materials; The solid materials are calculated by weight and include: 50-60 parts of desulfurized ash, 30-40 parts of mineral powder, 10 parts of cement, 1-5 parts of calcium chloride; (2) mixing water; the weight ratio of the mixing water to the solid material is 0.5-0.7:1; (3) foam; the amount of the foam is sufficient to make the volume of the bubbles account for 40-70% of the total volume of the wet desulfurization ash foam lightweight soil composition, and the wet desulfurization ash foam lightweight soil composition is obtained by mixing all the raw materials; The desulfurization ash is calcium desulfurization ash; The foam is formed by the reaction of a chemical foaming agent to generate gas; The raw materials of the foam include a chemical foaming agent and a foam stabilizer; the chemical foaming agent is a combination of aluminum sulfate and sodium bicarbonate; The weight ratio of the chemical foaming agent to the cement in the solid material is 5-12:10; The weight ratio of the foam stabilizer to the cement in the solid material is 0.3-0.9:10; The weight ratio of aluminum sulfate to sodium bicarbonate is 3-4:1; The prepared solutions of the aluminum sulfate and the sodium bicarbonate are prepared separately and then mixed before pouring at the construction site.

2. The desulfurization ash foam lightweight soil according to claim 1, characterized in that: The foam stabilizer is calcium stearate.

3. The desulfurization ash foam lightweight soil according to any one of claims 1 to 2, characterized in that: The content of calcium sulfite in the calcium desulfurization ash does not exceed 10% of the total weight of the calcium desulfurization ash; and the particle size of the calcium desulfurization ash is 1-10 μm.

4. The desulfurization ash foam lightweight soil according to any one of claims 1 to 2, characterized in that: The mineral powder is blast furnace slag powder; the cement is one of silicate cement and ordinary silicate cement.

5. The desulfurization ash foam lightweight soil according to any one of claims 1 to 2, characterized in that: The wet density of the wet desulfurized ash foam lightweight soil composition is 540-1000 kg / m 3 .

6. A method for preparing desulfurized ash foam lightweight soil according to any one of claims 1 to 2, characterized in that: The following steps are involved: Weigh the desulfurized ash, mineral powder, cement, aluminum sulfate, sodium bicarbonate, foam stabilizer, calcium chloride and mixing water for later use; The desulfurized ash, mineral powder, cement, aluminum sulfate, foam stabilizer, calcium chloride and part of the mixing water are mixed to form a first gelling slurry; According to the weight ratio of water to solid material, the sodium bicarbonate is added to the remaining mixed water to prepare a sodium bicarbonate solution; The first gelling slurry and the sodium bicarbonate solution are mixed and allowed to stand for foaming to obtain a wet desulfurized ash foamed lightweight soil composition; The desulfurized ash and mineral powder are mixed and ground, and then prepared into a first gelled slurry.

Images