A low-carbon cementitious material prepared from waste incineration fly ash and a method for preparing the same
By electrolyzing waste incineration fly ash and combining it with ion complexing and composite shrinkage reducing agents, a low-carbon cementitious material was prepared, which solved the problem of using waste incineration fly ash in alkali-activated slag cementitious materials and achieved a non-toxic, low-carbon, and high-performance cementitious material.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
- Filing Date
- 2025-12-16
- Publication Date
- 2026-06-26
AI Technical Summary
In existing technologies, when waste incineration fly ash is used in alkali-activated slag cementitious materials, it is necessary to pretreat harmful substances. Furthermore, the alkali activator is derived from chemical products, which leads to carbon emissions and environmental pollution, making it difficult to achieve both strong activation capacity and non-toxicity.
Electrolysis technology is used to treat fly ash from waste incineration. By controlling the electrolyte solution and current density, a high pH environment is created to decompose dioxins and reduce heavy metals. The modified fly ash is used as an alkaline activator, combined with ion complexing agents and composite shrinkage reducing agents to prepare low-carbon cementitious materials.
This method achieves the detoxification and efficient activation of fly ash from waste incineration. The prepared cementitious material is environmentally friendly, low-cost, has adjustable fluidity, excellent mechanical properties, minimal volume shrinkage, reduced carbon emissions, and lower production costs.
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Figure CN121609523B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of building materials technology, specifically to a low-carbon cementitious material and its preparation method, which is generated from fly ash from waste incineration and activated mineral powder. Background Technology
[0002] Compared to cement, alkali-activated slag cementitious materials reduce carbon emissions by 70-80%; meanwhile, their performance characteristics are comparable to cement. Therefore, alkali-activated slag cementitious materials are an important research area in the field of green building materials.
[0003] The raw materials for alkali-activated slag cementitious materials include alkali activators and precursors. Typically, alkali activators mainly include hydroxides, water glass, sulfates, and carbonates; the precursors are primarily slag, supplemented with small amounts of reactive solid waste such as fly ash and steel slag. However, alkali activators mainly originate from chemical production, causing significant carbon emissions and environmental pollution. Furthermore, the cost of alkali activators typically accounts for 40-60% of the cost of alkali-activated slag cementitious materials.
[0004] Studies show that waste incineration fly ash has the potential to be used as an alkaline activator for slag. Patent CN110125139A describes a method for co-treating dioxins and heavy metals in waste incineration fly ash using steel slag and slag, emphasizing that sulfates and calcium chloride in the fly ash can activate active components in the slag to generate Ca-Al-LDH and Ca-(Al, Fe)-AFt, etc. However, due to the high content and variety of harmful substances, waste incineration fly ash is typically used in small quantities and requires pretreatment when used in alkaline-activated slag cementitious materials.
[0005] Therefore, balancing strong activating ability with non-toxicity is a pressing problem that needs to be solved to achieve the widespread use of waste incineration fly ash in alkali-activated slag cementitious materials. Summary of the Invention
[0006] In order to overcome the above technical problems, the purpose of this invention is to provide a low-carbon cementitious material and its preparation method based on mineral powder activated by waste incineration fly ash. This material is environmentally friendly and low-cost in terms of component design, and has adjustable fluidity, excellent mechanical properties and minimal volume shrinkage in terms of performance.
[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0008] A low-carbon cementitious material derived from mineral powder activated by waste incineration fly ash comprises the following components by weight percentage: 8-12% modified waste incineration fly ash, 1-3% ion-complexed components, 2-6% composite shrinkage-reducing components, 55-65% mineral powder, and 23-28% water.
[0009] The modified waste incineration fly ash is a fine particulate matter rich in heavy metals, dioxins, and soluble salts, formed after the incineration of municipal solid waste, with a specific surface area of 2.0~6.0 m². 2 / g.
[0010] In the composite shrinkage-reducing component, the specific surface area of kaolin is 5.0~10.0 m². 2 / g, the specific surface area of magnesium oxide is 15.0~20.0 m². 2 / g; by weight percentage, kaolin 80~90%, magnesium oxide 10~20%.
[0011] The mineral powder is grade S95, which is a common commercial mineral powder and has universal applicability.
[0012] A method for preparing a low-carbon cementitious material from waste incineration fly ash-activated mineral powder includes the following steps:
[0013] S1. Preparation of modified waste incineration fly ash, ion complex components, and composite shrinkage-reducing components;
[0014] S2. The modified waste incineration fly ash, ion complexing component, composite shrinkage component, mineral powder, and mixing water are thoroughly mixed and stirred evenly to obtain the low-carbon cementitious material of mineral powder activated by waste incineration fly ash.
[0015] In step S1, the preparation of the modified waste incineration fly ash includes the following steps:
[0016] An electrolytic cell was constructed using graphite as the anode, copper as the cathode, and a 0.1–0.5 mol / L NaCl solution as the electrolyte. Waste incineration fly ash was added to the electrolytic cell and continuously stirred to form a slurry with a solid-liquid ratio of 1:5–1:10. A DC power supply was connected, and the current density was controlled at 5–20 mA / cm². 2 Modified municipal solid waste incineration fly ash is obtained by continuously electrolyzing it for 60-120 minutes, using NaOH to adjust the pH of the slurry to be no lower than 12.80, filtering and drying the slurry. Electrolysis technology can improve the activating ability of waste incineration fly ash to mineral powder while achieving non-toxicity.
[0017] In S1, the preparation of the ion complex component includes the following steps:
[0018] Choline and triethanolamine crystals are added to an ethanol solution and stirred thoroughly. By weight percentage, the choline content is 10-30%, the triethanolamine content is 20-40%, and the ethanol content is 30-70%. Ionic complexing agents improve the flowability of cementitious materials.
[0019] In S1, the preparation of the composite shrinkage component includes the following steps:
[0020] Kaolin and magnesium oxide are mixed and calcined at 800-1000℃ for 2-4 hours. Calcination at this temperature allows for simultaneous regulation of the reactivity of both kaolin and magnesium oxide. Therefore, they can continuously form water-absorbing / expanding species through hydration, effectively inhibiting the volume shrinkage of the cementitious material over a long period.
[0021] The beneficial effects of this invention are:
[0022] (1) Electrolysis is used to detoxify fly ash from waste incineration. Toxic substances in fly ash from waste incineration can be divided into two categories: dioxins and heavy metals. During electrolysis, the hydroxyl radicals and active chlorine generated at the anode can effectively attack and destroy the molecular structure of dioxins, decomposing them into carbon dioxide, water, and inorganic chloride ions, thus achieving complete detoxification. Through the reduction effect at the cathode, highly toxic and highly mobile heavy metal ions can be reduced to low-toxicity and low-mobility forms, ultimately forming metal hydroxide precipitates, reducing their environmental risk.
[0023] (2) Electrolysis enhances the activation capacity of waste incineration fly ash for slag activation. After electrolysis, the high pH environment (≥12.80) of waste incineration fly ash is the fundamental reason why it can effectively activate slag; the basic calcium chloride formed by chloride ion conversion is an important species for activating slag; the small amount of NaOH formed by NaCl conversion is a supplementary species for activating slag.
[0024] (3) The low-carbon cementitious material prepared by this invention using modified waste incineration fly ash as an alkali activator, mineral powder as a precursor, and combined with ion complexing agents and composite shrinkage reducing agents is environmentally friendly and cost-effective in terms of component design, and has adjustable fluidity, excellent mechanical properties, and minimal volume shrinkage in terms of performance. In the early stage, it benefits from the high pH value and abundant basic calcium chloride of the modified waste incineration fly ash, and the generated plate-like crystals are horizontally and tightly stacked to form a dense microstructure; in the later stage, due to the continuous hydration of mineral powder, the gel products and plate-like crystals intertwine, the crystal-gel ratio of the product is continuously optimized, and the density and uniformity of the microstructure are significantly improved. The carbon emission of the cementitious material is 153~226 kg / t, and the production cost is 278-335 RMB / t; the fluidity of the cementitious material is 260~320 mm, the 3 / 28-day compressive strength is 42~55 / 80~95 MPa, and the 360-day drying shrinkage is 800~1200×10 -6 . Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the electrolysis technology for fly ash from waste incineration in this invention.
[0026] Figure 2 The microstructure of the low-carbon cementitious material in this invention is shown in the early stage (left) and later stage (right). Detailed Implementation
[0027] The present invention will now be described in further detail with reference to the accompanying drawings.
[0028] like Figure 1 , Figure 2 As shown, the purpose of this invention is to provide a low-carbon cementitious material derived from waste incineration fly ash and activated mineral powder, comprising the following components by weight percentage: 8-12% modified waste incineration fly ash, 1-3% ion complexing component, 2-6% composite shrinkage component, 55-65% mineral powder, and 20-24% water.
[0029] In the early stages, the high pH conditions of the modified waste incineration fly ash create a liquid phase environment that effectively dissolves the aluminum phase of the mineral powder. Based on this, the abundant basic calcium chloride in the modified waste incineration fly ash reacts with the aluminum phase to generate a large number of plate-like crystals. After the plate-like crystals are horizontally and tightly stacked, they form a dense microstructure, ensuring the early strength of the low-carbon cementitious material. In the later stages, the gel products generated by the continuous hydration of the mineral powder gradually encapsulate the plate-like crystals, optimizing the crystal-gel ratio of the reaction products. Following the principle of closest packing, this improves the density and uniformity of the microstructure, ensuring the continuous development of the mechanical properties of the low-carbon cementitious material.
[0030] The high pH conditions and abundant basic calcium chloride species in modified waste incineration fly ash are important reasons for its effective activation of mineral powder; modified waste incineration fly ash is environmentally friendly and inexpensive when used as an alkaline activator; ionic complexing agents and composite shrinkage reducing agents can improve the performance defects of cementitious materials such as uncontrollable fluidity and significant volume shrinkage.
[0031] like Figure 2 As shown, the modified waste incineration fly ash is a fine particulate matter rich in heavy metals, dioxins, and soluble salts, formed after the incineration of municipal solid waste, with a specific surface area of 2.0~6.0 m². 2 / g.
[0032] Furthermore, in the composite shrinkage-reducing component, the specific surface area of kaolin is 5.0~10.0 m². 2 / g, the specific surface area of magnesium oxide is 15.0~20.0 m². 2 / g. By weight percentage, kaolin 80-90%, magnesium oxide 10-20%. The particle size of kaolin and magnesium oxide is compatible with the particle sizes of other raw materials, which is beneficial to improving the density of the cementitious material. Experiments of this invention demonstrate that the specific surface area of kaolin is 5.0-10.0 m². 2 / g, the specific surface area of magnesium oxide is 15.0~20.0 m². 2 / g, the density of the prepared cementitious material is extremely high.
[0033] Furthermore, the mineral powder is grade S95. The mineral powder used in this invention is a common commercial mineral powder, and the prepared cementitious material has universality in terms of composition design.
[0034] The invention uses modified waste incineration fly ash as an alkali activator, mineral powder as a precursor, and ion complexing agents and composite shrinkage reducing agents to prepare a low-carbon cementitious material. In terms of component design, it is environmentally friendly and low-cost. In terms of performance, it has adjustable fluidity, excellent mechanical properties, and minimal volume shrinkage.
[0035] Another object of the present invention is to provide a method for preparing a low-carbon cementitious material from waste incineration fly ash activated mineral powder as described above, comprising the following steps:
[0036] S1. Preparation of modified waste incineration fly ash, ion complex components, and composite shrinkage-reducing components;
[0037] S2. The modified waste incineration fly ash, ion complexing component, composite shrinkage component, mineral powder, and mixing water are thoroughly mixed and stirred evenly to obtain the low-carbon cementitious material of mineral powder activated by waste incineration fly ash.
[0038] Furthermore, such as Figure 1 As shown, the preparation method of modified waste incineration fly ash includes: constructing an electrolytic cell with graphite as the anode, copper as the cathode, and 0.1~0.5 mol / L NaCl solution as the electrolyte; adding waste incineration fly ash to the electrolytic cell and continuously stirring to form a slurry; the mass ratio of waste incineration fly ash to NaCl solution being 1:5~1:10; connecting a DC power supply and controlling the current density to be 5~20 mA / cm². 2 Modified municipal solid waste incineration fly ash is obtained by continuously electrolyzing the fly ash for 60-120 minutes, using NaOH to adjust the pH of the slurry to be no less than 12.80, filtering and drying the slurry.
[0039] During electrolysis, the hydroxyl radicals and active chlorine generated at the anode effectively attack and destroy the molecular structure of dioxins, decomposing them into carbon dioxide, water, and inorganic chloride ions, thus achieving complete detoxification. Through the reduction effect at the cathode, highly toxic and highly mobile heavy metal ions are reduced to less toxic and less mobile forms, ultimately forming metal hydroxide precipitates, reducing their environmental risk. After electrolysis, the high pH environment (≥12.80) of the waste incineration fly ash is the fundamental reason why it can effectively activate slag; the basic calcium chloride formed by chloride ion conversion is an important species for activating slag; and the small amount of NaOH formed by NaCl conversion is a supplementary species for activating slag.
[0040] Furthermore, the indexing method for ion-complexed components includes: adding choline and triethanolamine crystals to an ethanol solution and stirring thoroughly, with the weight percentages being 10-30% choline, 20-40% triethanolamine, and 30-70% ethanol. Ion-complexing agents can improve the flowability of cementitious materials.
[0041] By utilizing the electrostatic repulsion and ionic complexation of choline and triethanolamine hydroxyl groups, the flowability of cementitious materials can be improved and the flowability can be adjusted.
[0042] Furthermore, the preparation method of the composite shrinkage component includes: mixing kaolin and magnesium oxide and calcining at 800~1000℃ for 2~4 hours.
[0043] The continuous hydration of kaolin and magnesium oxide can inhibit the volume shrinkage of cementitious materials by inhibiting the growth of water-absorbing and expansive species such as high-alumina calcium silicate hydrate and magnesium aluminate hydrate.
[0044] This invention utilizes electrolysis to detoxify dioxins in waste incineration fly ash and convert heavy metals, successfully detoxifying the fly ash. Simultaneously, it increases the pH value and basic calcium chloride content of the fly ash, enhancing its activating ability on slag. Therefore, the modified waste incineration fly ash, as an alkaline activator, possesses environmental friendliness and excellent activating ability. Furthermore, the electrostatic repulsion and ionic complexation of choline and triethanolamine hydroxyl groups in the ionic complexing component improve the flowability of the cementitious material and achieve adjustable flowability. The water-absorbing and expansive species introduced through the continuous hydration of kaolin and magnesium oxide in the composite shrinkage-reducing component inhibit the volume shrinkage of the cementitious material. The carbon emissions of the cementitious material are 153~226 kg / t, and the production cost is ¥278-335 / t. The flowability of the cementitious material is 260~320 mm, the 3 / 28-day compressive strength is 42~55 / 80~95 MPa, and the 360-day drying shrinkage is 800~1200×10⁻⁶. -6 .
[0045] Based on the above embodiments, the present invention is further illustrated below with a method for preparing low-carbon cementitious materials from waste incineration fly ash-activated mineral powder. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed according to the manufacturer's recommended conditions. Unless otherwise stated, percentages and parts are by weight.
[0046] Table 1. Preparation and performance parameters of modified waste incineration fly ash in Examples 1-6
[0047]
[0048] Table 2. Combination ratios of ion-complexed components in Examples 1-6
[0049]
[0050] Table 3. Preparation parameters of the composite shrinkage components in Examples 1-6
[0051]
[0052] Table 4. Proportions of low-carbon cementitious materials for mineral powder activated by waste incineration fly ash in Examples 1-6
[0053]
[0054] During implementation, modified waste incineration fly ash is prepared according to the technical scheme in Table 1, ion complexing components are prepared according to the technical scheme in Table 2, composite shrinkage-reducing components are prepared according to the technical scheme in Table 3, and modified waste incineration fly ash, ion complexing components, composite shrinkage-reducing components, mineral powder, and water are thoroughly mixed and stirred evenly according to the technical scheme in Table 4 to obtain a low-carbon cementitious material that uses waste incineration fly ash to activate mineral powder.
[0055] The low-carbon cementitious materials prepared in Examples 1-6 using fly ash from waste incineration to activate mineral powder were subjected to performance tests, and the results are shown in Table 5. The relevant performance testing methods were conducted in accordance with GB / T 8077-2023 "Test Method for Homogeneity of Concrete Admixtures", GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)", and JC / T 603-2004 "Test Method for Drying Shrinkage of Cement Mortar".
[0056] Table 5 Performance parameters of low-carbon cementitious materials derived from waste incineration fly ash-activated mineral powder in Examples 1-6
[0057]
[0058] Table 5 shows that the low-carbon cementitious material prepared according to the technical solution of this invention, which is composed of mineral powder activated by fly ash from waste incineration, has a flowability of 260~320 mm, a 3 / 28-day compressive strength of 42~55 / 80~95 MPa, and a 360-day drying shrinkage of 800~1200×10⁻⁶ MPa. -6 Carbon emissions range from 153 to 226 kg / t, and production costs range from 278 to 335 ￥ / t.
[0059] In summary, the low-carbon cementitious material prepared by this invention, which uses electrolysis technology to detoxify the fly ash and enhance its ability to activate mineral powder, achieves high-value utilization of hazardous solid waste. By synergistically combining ion-complexing components and composite shrinkage-reducing components, it overcomes the performance defects of cementitious materials such as poor fluidity and significant volume shrinkage, thus achieving green and sustainable development.
Claims
1. A low-carbon cementitious material derived from mineral powder activated by waste incineration fly ash, characterized in that, By weight percentage, it comprises the following components: 8-12% modified waste incineration fly ash, 1-3% ion-complexed components, 2-6% composite shrinkage-reducing components, 55-65% mineral powder, and 23-28% water; The method for preparing the modified waste incineration fly ash includes the following steps: An electrolytic cell was constructed using graphite as the anode, copper as the cathode, and a 0.1–0.5 mol / L NaCl solution as the electrolyte. Waste incineration fly ash was added to the electrolytic cell and continuously stirred to form a slurry. The mass ratio of waste incineration fly ash to NaCl solution was 1:5–1:
10. A DC power supply was connected, and the current density was controlled at 5–20 mA / cm². 2 The waste incineration fly ash was continuously electrolyzed for 60-120 minutes. The pH of the slurry was adjusted to be no lower than 12.80 using NaOH. After filtration and drying, the modified waste incineration fly ash was obtained. The composite shrinkage-reducing components, by weight percentage, consist of 80-90% kaolin and 10-20% magnesium oxide.
2. The low-carbon cementitious material derived from waste incineration fly ash-activated mineral powder according to claim 1, characterized in that, The modified waste incineration fly ash is a fine particulate matter rich in heavy metals, dioxins, and soluble salts, formed after the incineration of municipal solid waste, with a specific surface area of 2.0~6.0 m². 2 / g.
3. The low-carbon cementitious material derived from waste incineration fly ash-activated mineral powder according to claim 1, characterized in that, In the composite shrinkage-reducing component, the specific surface area of kaolin is 5.0~10.0 m². 2 / g, the specific surface area of magnesium oxide is 15.0~20.0 m². 2 / g.
4. A method for preparing a low-carbon cementitious material from waste incineration fly ash-activated mineral powder according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Preparation of modified waste incineration fly ash, ion complex components, and composite shrinkage-reducing components; S2. The modified waste incineration fly ash, ion complexing components, composite shrinkage components, mineral powder, and mixing water are thoroughly mixed and stirred evenly to obtain a low-carbon cementitious material that is activated by mineral powder from waste incineration fly ash.
5. The method for preparing a low-carbon cementitious material from waste incineration fly ash-activated mineral powder according to claim 4, characterized in that, In S1, the preparation of the ion complex component includes the following steps: Add choline and triethanolamine crystals to an ethanol solution and stir thoroughly. By weight percentage, choline is 10-30%, triethanolamine is 20-40%, and ethanol is 30-70%.
6. The method for preparing a low-carbon cementitious material from waste incineration fly ash-activated mineral powder according to claim 4, characterized in that, In S1, the preparation of the composite shrinkage component includes the following steps: Kaolin and magnesium oxide are mixed and calcined at 800-1000℃ for 2-4 hours. By weight percentage, kaolin is 80-90% and magnesium oxide is 10-20%.