Detoxified waste incineration fly ash-slag composite alkali-activated cementing material and preparation method thereof

Abstract

The invention discloses a detoxified waste incineration fly ash-slag composite alkali-activated cementing material and a preparation method of the detoxified waste incineration fly ash-slag composite alkali-activated cementing material, and belongs to the technical field of harmless and resource utilization of dangerous solid wastes. The raw materials comprise precursor slag, alkali activator detoxified waste incineration fly ash, standard sand and water. The detoxified waste incineration fly ash is obtained by performing mechanochemical grinding on waste incineration fly ash and an additive, and the degradation effect of dioxin in the fly ash can be improved. According to the cementing material prepared by taking the detoxified waste incineration fly ash as a single alkali activator, the cost of producing the activator is remarkably reduced, and meanwhile, due to the adoption of a low-temperature mechanochemical process for detoxification, the carbon footprint is relatively low, the problems of environmental pollution and land occupation caused by solid waste stockpiling are solved, and dual-carbon emission reduction is promoted; in addition, the cementing material prepared by the preparation method can be used in the fields of pavement filling, wall interior and the like in building materials for resource utilization.

Description

Technical Field

[0001] This invention belongs to the technical field of harmless and resource-based utilization of hazardous solid waste, and particularly relates to a detoxified waste incineration fly ash-slag composite alkali-activated cementitious material and its preparation method. Background Technology

[0002] With the further advancement of urbanization, the production of municipal solid waste continues to increase. By 2050, the annual production of municipal solid waste globally is projected to reach 3.4 billion tons. Currently, incineration remains the primary method for treating municipal solid waste, offering significant advantages in volume reduction and energy recovery. However, this process inevitably produces incineration residues, including incinerator fly ash and bottom ash. Among these, incinerator fly ash is classified as hazardous waste due to its high content of heavy metals and dioxins. Therefore, its safe disposal should be given greater attention. Treatment methods for incinerator fly ash include sintering, washing, and stabilization / solidification. Sintering is accompanied by high energy consumption. Furthermore, at high temperatures, low-melting-point heavy metals in the fly ash can leach into the flue gas, causing secondary pollution. Washing can remove most soluble heavy metals and chlorine, but inevitably generates a large amount of contaminated wastewater. Stabilization / solidification is achieved by mixing hazardous waste with a binder, during which the leaching behavior of harmful components is limited by the encapsulation structure or the formation of chemical bonds. Ordinary silicate cement is the most commonly used stabilization / solidification binder for the harmless treatment of fly ash. However, the production of ordinary silicate cement is accompanied by high energy consumption and high carbon emissions.

[0003] Alkali-activated cementitious materials are sustainable, cement-free binders composed of aluminosilicate precursors (including natural minerals and industrial waste) and alkali activators (such as sodium hydroxide and calcium hydroxide). Alkali-activated cementitious materials have advantages such as low carbon content, high strength, and good durability, and are considered a substitute for ordinary silicate cement. Since aluminosilicates are lacking in waste incineration fly ash, other precursors, such as ground granular blast furnace slag, have been introduced to prepare alkali-activated cementitious materials based on waste incineration fly ash. Almost all research on alkali-activated cementitious materials based on waste incineration fly ash has chosen a two-component alkali activator composed of sodium hydroxide and sodium silicate water glass. This is a traditional commercial alkali activator, but it ignores the high alkalinity characteristics of waste incineration fly ash. Due to the restrictions on HCl content in Chinese standard GB 18485-2001, as well as SO2 and other pollutants in the flue gas generated from municipal solid waste incineration, alkaline substances such as Ca(OH)2 are crucial for flue gas deacidification. This results in the pH value of waste incineration fly ash typically exceeding 12. Therefore, the present invention can activate the reaction of highly active precursors using only waste incineration fly ash.

[0004] Currently, with the development of the world economy, industrial solid wastes such as steel slag, gasification slag, coal gangue, municipal solid waste incineration fly ash, rice husk ash, and glass powder have become the main focus of cementitious material research. However, traditional alkaline activators have the following drawbacks: 1. As strongly alkaline liquid solutions, they are difficult to handle on-site, posing health and safety risks. 2. The costs, implicit energy, and environmental impacts associated with activator production, especially sodium silicate, which is typically produced by melting sodium carbonate and silica, emits large amounts of CO2 at temperatures of 1200-1400℃. This invention uses detoxified municipal solid waste incineration fly ash as a single alkaline activator to prepare low-carbon, cement-free, alkaline-activated cementitious materials. The macroscopic properties of the prepared cementitious materials, including their mechanical properties and processability, were evaluated and compared with those of traditional alkaline-activated materials. This invention is expected to provide guidance for the value-added recycling of hazardous waste and the development of novel low-carbon cementitious materials.

[0005] A search of existing patents revealed the following:

[0006] (1) Chinese Patent CN119462039A, entitled "A Composite Alkali-Activated Cementitious Material for Dechlorinated and Detoxified Fly Ash-Waste Glass Powder-Slag and Its Preparation Method Thereof," discloses a composite alkali-activated cementitious material for dechlorinated and detoxified fly ash-waste glass powder-slag and its preparation method. The alkali-activated cementitious material is mainly composed of hydrated calcium aluminosilicate gel and hydrated sodium aluminosilicate gel. The raw material composition includes: dechlorinated and detoxified fly ash, waste glass powder, slag and alkali activator, wherein the alkali activator is prepared by sodium silicate solution and sodium hydroxide solid.

[0007] For example, Chinese patent CN117088627A, entitled "An Alkali-Activated Cementitious Material and Its Preparation Method and Application," discloses an alkali-activated cementitious material comprising a composite precursor material and an alkali activator. The composite precursor material is composed of coal gangue and incineration fly ash or bottom ash. The alkali activator comprises one or both of NaOH and Na2SiO3 solution.

[0008] The above patents involve alkali-activated cementitious materials that maximize the potential cementitious activity of fly ash treatment products by fusing the components of various mineral materials. This provides a consolidation and cementing effect for low-carbon cementitious materials, reducing the amount of cement used in concrete and lowering engineering costs. Simultaneously, it can improve the physicochemical properties of low-carbon cementitious materials, achieving synergistic effects across multiple products. Through the cementing effect of the cementitious material, it can provide a new, high-performance low-carbon cementitious material that can replace cement, and it can also reuse municipal solid waste incineration fly ash and general industrial solid waste, achieving the harmless and resource-based disposal of incineration fly ash. However, the waste incineration fly ash in the above patents is used as a precursor in alkali-activated cementitious materials, and the alkali activators mainly use some traditional commercial activators such as NaOH and Na2SiO3 solutions. Summary of the Invention

[0009] To address the aforementioned technical problems, this invention proposes a composite alkali-activated cementitious material made from detoxified waste incineration fly ash and slag, and its preparation method. Compared with the prior art, this invention provides another technical concept, namely, utilizing the high alkalinity of detoxified waste incineration fly ash as an alkali activator to prepare a single-component alkali-activated cementitious material.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A detoxified waste incineration fly ash-slag composite alkali-activated cementitious material, the raw materials of which are:

[0012] Precursor slag, alkali activator detoxified waste incineration fly ash, standard sand and water;

[0013] The detoxified waste incineration fly ash is obtained by mechanically and chemically grinding waste incineration fly ash and additives.

[0014] Optionally, the additive is selected from at least one of CaO, SiO2, Al2O3 and MgO.

[0015] Furthermore, the mass ratio of the waste incineration fly ash to the additive is 7:3.

[0016] Furthermore, the grinding time is 20 seconds.

[0017] Furthermore, the toxicity equivalent concentration (1-TEQ) of the detoxified waste incineration fly ash is less than 50 TEQ·kg. −1 .

[0018] Optionally, the mass ratio of the detoxified waste incineration fly ash to slag is (1-6):(4-9); preferably 1:9, 2:8, 4:6, 6:4; more preferably 4:6.

[0019] Optionally, the detoxified waste incineration fly ash-slag composite alkali-activated cementitious material, by weight, comprises the following raw materials:

[0020] The composition of the waste incineration product consists of 45-270 parts of detoxified fly ash, 180-405 parts of slag, 1350 parts of standard sand, and 225 parts of water.

[0021] Furthermore, the detoxified waste incineration fly ash-slag composite alkali-activated cementitious material, by weight, comprises the following raw materials:

[0022] The samples contained 180 parts of detoxified waste incineration fly ash, 270 parts of slag, 1350 parts of standard sand, and 225 parts of water.

[0023] The preparation method of the above-mentioned detoxified waste incineration fly ash-slag composite alkali-activated cementitious material includes the following steps:

[0024] The detoxified waste incineration fly ash and slag are mixed evenly, then water is added and stirred at low speed. Then standard sand is added and stirred at high speed, shaped and cured to prepare the detoxified waste incineration fly ash-slag composite alkali-activated cementitious material.

[0025] Optionally, the low-speed stirring conditions are: stirring at a low speed of 140 rpm for 30 s ± 1 s.

[0026] Optionally, the high-speed stirring conditions are: stirring at 285 rpm for 90 s ± 1 s.

[0027] Optionally, the 28-day flexural strength of the detoxified waste incineration fly ash-slag composite alkali-activated cementitious material is 7.0-8.2 MPa; the 28-day compressive strength is 21.28-36.59 MPa.

[0028] Compared with the prior art, the present invention has the following advantages and technical effects:

[0029] This invention aims to synthesize a detoxified fly ash-based alkali-activated cementitious material, promoting its low-cost resource utilization. Specifically, it utilizes detoxified waste incineration fly ash as a single alkali activator in alkali-activated cementitious materials, developing an innovative low-carbon, cement-free cementitious material. The cementitious material prepared by this invention exhibits excellent mechanical properties; for example, the cementitious material with 40wt% detoxified fly ash can achieve a compressive strength of 36.59 MPa after 28 days. Specifically:

[0030] 1. This invention employs a mechanochemical method to detoxify dioxins from waste incineration fly ash. The treated fly ash exhibits smaller particle size, increased specific surface area, and a more compact structure, enhancing its advantages for co-processing in cement kilns or blending in concrete production. Furthermore, the mechanochemical method requires simple equipment, uses inexpensive additives, and does not generate new pollution, all of which contribute to its industrial applications.

[0031] 2. The alkali-activated cementitious material prepared by this invention has low energy consumption, low emissions, and superior performance. Specifically, by using industrial solid waste slag as a precursor and detoxified waste incineration fly ash as an alkali activator, the prepared alkali-activated cementitious material exhibits excellent mechanical and workability properties. This single-component cementitious material only needs to be mixed with powder and water, avoiding the use of traditional commercial liquid activators. It is convenient, efficient, requires less dosage, and has significant effects, greatly increasing the utilization rate of solid waste and saving the amount of high-carbon cement used, thus achieving energy conservation and emission reduction.

[0032] 3. The fly ash-based alkali-activated cementitious material disclosed in this invention exhibits macroscopic properties comparable to other cementitious materials and can be used as a potential substitute for ordinary silicate cement, with broad application prospects. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 A distribution map of dioxin toxicity equivalent concentrations for Taizhou original fly ash and detoxified waste incineration fly ash (30% CaO Taizhou fly ash);

[0035] Figure 2 Sample image of a composite alkali-activated cementitious material made from fly ash and slag from detoxified waste incineration;

[0036] Figure 3 The test results of flexural strength (a) and compressive strength (b) of the detoxified waste incineration fly ash-slag composite alkali-activated cementitious materials prepared with different raw material ratios in Example 1 are shown.

[0037] Figure 4 The results show the flowability test results of the detoxified waste incineration fly ash-slag composite alkali-activated cementitious materials prepared with different raw material ratios in Example 1. Detailed Implementation

[0038] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0039] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0040] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0041] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0042] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0043] Unless otherwise specified, "room temperature" in this invention refers to 20-30℃.

[0044] Unless otherwise specified, the term "parts" in this invention refers to parts by weight.

[0045] All raw materials used in this invention were purchased from the market.

[0046] The technical solution of the present invention will be further illustrated by the following embodiments.

[0047] Example 1

[0048] A method for preparing a low-carbon cementitious material based on waste incineration fly ash includes the following steps:

[0049] I. Mechanochemical Treatment Methods for Dioxin Dechlorination and Detoxification in Waste Incineration Fly Ash

[0050] ①The specific steps for fly ash detoxification are as follows:

[0051] (1) Weigh a certain amount of the original Taizhou fluidized bed waste incineration fly ash and a certain amount of additive CaO.

[0052] (2) Put the weighed fly ash and additives into the vibratory mill and grind for 20 seconds.

[0053] (3) All the physicochemical properties of fly ash will change during grinding. Mechanochemical methods can improve the degradation effect of dioxins in fly ash. During the operation of the vibratory mill, the grinding disc, fly ash and vibratory mill jar collide with each other. In the vibratory mill jar, fly ash will be subjected to different mechanical forces such as impact, grinding, crushing, friction and shearing. Its structure and basic physicochemical properties will change after the mechanochemical reaction activated by mechanical energy. The treated fly ash has a smaller particle size, a larger specific surface area and a more compact structure.

[0054] (4) The toxicity equivalent concentration of the pulverized fly ash and the original fly ash was tested to verify the detoxification efficiency.

[0055] ②Specific proportions:

[0056] 35g of fly ash from waste incineration and 15g of CaO additive.

[0057] ③Characteristics of dioxin detoxification efficiency in fly ash:

[0058] The composition and toxicity equivalent (I-TEQ) of dioxins in raw fly ash and detoxified fly ash were tested, and the results are shown in Table 1. Adding CaO as a dechlorinating agent during the grinding process can improve the removal efficiency of chlorinated organic matter. The dechlorination process of the vibratory mill with CaO as a dehalogenating agent is shown in Equation (1).

[0059] (1)

[0060] In the formula: C 12 H x Cl y Representing dioxins. This invention adds 30% CaO as a grinding aid; the change in dioxin toxicity equivalent concentration in fly ash after grinding is shown below. Figure 1 As shown, the most abundant dioxin isomer in the original fly ash was PCDDs (OCDD), at 2400 ng / kg. −1 The highest toxicity equivalent was found in PCDFs 2,3,4,7,8-P5CDF, at 28 ng TEQ·kg. −1 After detoxification using mechanochemical methods, the removal rates of dioxins, PCDDs, and PCDFs were 63%, 59%, and 72%, respectively. The dioxin mass fraction decreased from 4752 ng·kg⁻¹. −1 Reduced to 1735.22 ng·kg −1 The removal rate reached 63%, and the toxicity equivalent decreased from 101.25 ng TEQ·kg. −1 Reduced to 34.44 ng TEQ·kg −1 The pollution level is lower than the standard set in the Technical Specification for Pollution Control of Fly Ash from Municipal Solid Waste Incineration (Trial) HJ 1134—2020 (i.e., 50 TEQ·kg). −1 ).

[0061] Table 1. Mass fraction and toxicity equivalent of dioxins in raw fly ash and detoxified fly ash

[0062]

[0063] The removal mechanism of chlorinated organic compounds by mechanochemical decomposition is achieved through stepwise dechlorination, with an average degree of chlorination (Cl). d It is an important indicator for evaluating dioxin removal efficiency. Its calculation formula is shown in equation (2). Where: Cl d The average chlorination degree of dioxins; f i n represents the mass percentage of a single dioxin homologue relative to the total dioxin concentration. i This represents the number of chlorine atoms on the dioxin molecule.

[0064] (2)

[0065] The calculated chloride degree of fly ash is shown in Table 2. It can be seen that as the grinding disc, fly ash, additives, and vibrating mill collide with each other, the fly ash undergoes various mechanical forces such as impact, grinding, crushing, friction, and shearing within the vibrating mill, resulting in a decrease in chloride degree. The chloride degree of dioxins decreased to 7.42. This result confirms that mechanochemical treatment can promote the dechlorination process of dioxins, with PCDDs showing higher dechlorination efficiency than PCDFs. The PCDFs / PCDDs ratio was less than 1 in all cases. This result indicates that dioxins are mainly synthesized through precursors.

[0066] Table 2. PCDFs / PCDDs values ​​and chlorination degree (Cl) of fly ash d

[0067]

[0068] II. Using the detoxified waste incineration fly ash obtained after mechanochemical treatment in step one as an alkali activator, prepare fly ash-slag composite alkali-activated cementitious material.

[0069] ①Ingredients:

[0070] An alkali-activated cementitious material includes a precursor material and an alkali activator; the precursor material is slag; the alkali activator is detoxified fly ash. The total raw materials include four types: Chinese ISO standard sand, water, detoxified fly ash, and slag.

[0071] ② Mixing ratio:

[0072] The mortar mix proportion is one part detoxified fly ash and slag, three parts Chinese ISO standard sand, and half a part water (water-cement ratio w / c = 0.50). Each batch of materials requires 450g of detoxified fly ash and slag, 1350g of sand, and 225g of water. Three specimens are formed from one mix proportion. The detoxified fly ash accounts for 10%, 20%, 40%, and 60% of the total mass of slag and detoxified fly ash, respectively, as shown in Table 3.

[0073] Table 3. Mix proportions of detoxified waste incineration fly ash-slag composite alkali-activated cementitious material

[0074]

[0075] ③The preparation steps of the cementitious material are as follows:

[0076] (1) Weighing: According to the data in Table 3, weigh 45g, 90g, 180g and 270g of detoxified fly ash respectively; weigh 405g, 360g, 270g and 180g of slag respectively; weigh 225g of water; and weigh 4 bags (1350g) of standard sand.

[0077] (2) Mixing: Mix 45g of detoxified fly ash and 405g of slag, 90g of detoxified fly ash and 360g of slag, 180g of detoxified fly ash and 270g of slag, and 270g of detoxified fly ash and 180g of slag thoroughly.

[0078] (3) Mixing: The mortar is mixed using a mixer according to the following procedure. It can be controlled automatically or manually:

[0079] a) Add the mixed detoxified fly ash and slag to the pot, then add water, fix the pot on the fixed frame, and raise it to the working position.

[0080] b) Start the machine immediately, first mix at low speed for 30s±1s, then add the standard sand evenly at the beginning of the second 30s±1s; then adjust the mixer to high speed and mix for another 30s±1s.

[0081] c) Stop mixing for 90 seconds. Within 15 seconds ± 1 second after stopping mixing, lower the mixing pot and use a scraper to scrape the mortar on the blades, pot walls and bottom into the pot.

[0082] d) Continue stirring at high speed for another 60s ± 1s;

[0083] e) Flowability test: The flowability of cementitious materials is tested using a cement mortar flowability tester in accordance with the flowability test method in the national standard GB / T2419-2005 "Method for Determination of Flowability of Cement Mortar".

[0084] f) Molding: Molding is carried out immediately after the mortar is prepared. A 40mm×40mm×160mm steel mold and mold sleeve are fixed on a vibrating table. The mortar on the pot wall is cleaned into the pot using a scoop, and the mortar is turned and stirred to make it more uniform. During molding, the mortar is filled into the mold in two layers. For the first layer, approximately 300g of mortar is placed in each slot. The mortar is first spread along the length of the mold using a scoop to fill the slots. Then, a large material spreader is placed vertically on top of the mold sleeve and spread evenly along each slot once. The mixture is then vibrated 60 times. The second layer of mortar is then filled. The mortar is spread along the length of the mold using a scoop to fill the slots, but without touching the already vibrated mortar. A small material spreader is then used to spread it evenly, and the mixture is vibrated 60 times. During each vibration, a piece of cotton gauze, slightly larger than the mold sleeve but wet and wrung out, can be placed on the mold sleeve to prevent mortar splattering. After molding, the samples are marked with a brush.

[0085] (4) Curing: Cover with polyethylene plastic film and pre-cur at room temperature for one day. After pre-curing, the hardened slurry is demolded and transferred to a standard curing chamber (20 ℃, 95 % humidity) for curing for 3 days, 7 days and 28 days respectively.

[0086] Figure 2Sample image of a composite alkali-activated cementitious material made from fly ash and slag from detoxified waste incineration.

[0087] ④ Test methods for the strength of cementitious materials:

[0088] The compressive and flexural strength testing methods for the samples prepared in this invention are based on GB / T17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)". A YAW-300·10B microcomputer-controlled compressive and flexural strength testing machine was used to test the compressive and flexural strength of samples prepared under different test conditions.

[0089] ⑤ Strength test results of different alkali-activated cementitious materials.

[0090] The test results of flexural strength and compressive strength of samples with different ratios are shown in Table 4.

[0091] Table 4. Test results of flexural strength and compressive strength of samples with different proportions.

[0092]

[0093] Figure 3 The figures show the test results of flexural strength (a) and compressive strength (b) of the detoxified waste incineration fly ash-slag composite alkali-activated cementitious materials prepared with different raw material ratios in Example 1.

[0094] ⑥ Flowability test results of different alkali-activated cementitious materials.

[0095] Figure 4 The graph shows the flowability test results of the detoxified waste incineration fly ash-slag composite alkali-activated cementitious materials prepared with different raw material ratios in Example 1.

[0096] Comparative Example 1

[0097] The only difference from Example 1 is the type and proportion of raw materials used, as shown in Table 5.

[0098] Table 5

[0099]

[0100] The same preparation process and testing methods were used as in Example 1. The flexural and compressive strengths of the samples prepared in Comparative Example 1 are shown in Table 6; the flowability was 209 mm.

[0101] Table 6

[0102]

[0103] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A detoxified waste incineration fly ash-slag composite alkali-activated cementitious material, characterized in that, The raw materials are: Precursor slag, alkali activator detoxified waste incineration fly ash, standard sand and water; The detoxified waste incineration fly ash is obtained by mechanically and chemically grinding waste incineration fly ash and additives.

2. The detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 1, characterized in that, The additive is selected from at least one of CaO, SiO2, Al2O3 or MgO.

3. The detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 1, characterized in that, The mass ratio of the waste incineration fly ash to the additive is 7:

3.

4. The detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 1, characterized in that, The toxicity equivalent concentration of the detoxified waste incineration fly ash is less than 50 TEQ·kg. −1 .

5. The detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 1, characterized in that, The mass ratio of the detoxified waste incineration fly ash to slag is (1-6): (4-9).

6. The detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 1, characterized in that, The raw materials, by weight, are: The composition of the waste incineration product consists of 45-270 parts of detoxified fly ash, 180-405 parts of slag, 1350 parts of standard sand, and 225 parts of water.

7. The detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 6, characterized in that, The raw materials, by weight, are: The samples contained 180 parts of detoxified waste incineration fly ash, 270 parts of slag, 1350 parts of standard sand, and 225 parts of water.

8. A method for preparing a detoxified waste incineration fly ash-slag composite alkali-activated cementitious material, characterized in that, Includes the following steps: The detoxified waste incineration fly ash and slag are mixed evenly, then water is added and stirred at low speed. Then standard sand is added and stirred at high speed, shaped and cured to prepare the detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to any one of claims 1-7.

9. The preparation method of a detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 8, characterized in that, The conditions for the low-speed stirring are: stirring at a low speed of 140 rpm for 29-31 seconds; and / or, The conditions for high-speed stirring are: stirring at 285 rpm for 89-91 seconds.

10. The preparation method of a detoxified waste incineration fly ash-slag composite alkali-activated cementitious material according to claim 8, characterized in that, The 28-day flexural strength of the detoxified waste incineration fly ash-slag composite alkali-activated cementitious material is 7.0-8.2 MPa; the 28-day compressive strength is 21.28-36.59 MPa.

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