High-calcium high-sulfur circulating fluidized bed ash-based full-solid waste cementing material and preparation method thereof

Abstract

The present application relates to solid waste resource utilization technical field, disclose high calcium high sulfur circulating fluidized bed ash base full solid waste cementing material and its preparation method, the cementing material is composed of the following quality parts of components: high calcium high sulfur circulating fluidized bed ash base composite admixture 85~97 parts, siliceous active filler 1~8 parts, composite sulfate-alkali activator 2~10 parts.The composite admixture is made by synergistic grinding of circulating fluidized bed fly ash, furnace bottom slag and granulated blast furnace slag;The composite sulfate-alkali activator is compounded by alkaline component, sodium sulfate component and desulfurization gypsum.The preparation method of the present application is to synergistically grind multiple solid wastes to improve their overall activity.The present application effectively controls the hydration reaction process through the synergistic effect of different dissolution rate components in the composite activator, and solves the contradiction between the activity of high calcium high sulfur solid waste system and the controllability of the reaction, and the volume stability in later period.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, specifically to high-calcium and high-sulfur circulating fluidized bed ash-based all-solid waste cementitious materials and their preparation methods. Background Technology

[0002] Circulating fluidized bed (CFB) combustion technology is widely used in power and heat production due to its wide fuel adaptability and efficient desulfurization. However, it also generates a large amount of CFB ash. This type of ash, especially when using high-sulfur coal and in-furnace limestone desulfurization processes, is typically rich in calcium oxide and sulfate, and is known as high-calcium, high-sulfur CFB ash. Utilizing this industrial solid waste as a cementing material is an effective way to achieve energy conservation, emission reduction, and sustainable development.

[0003] High-calcium, high-sulfur circulating fluidized bed ash contains a certain amount of active silica, alumina, and free calcium oxide (f-CaO) and sulfate as potential endogenous activators, providing the basic chemical composition for use as a cementing material. However, its direct or simple application in engineering faces significant technical challenges. First, most of the silica and alumina components in the ash exist in stable crystalline or semi-crystalline forms, with very limited hydration activity; external activation is necessary to realize its cementing potential.

[0004] In current technical practices, chemical activators are commonly used to enhance the reactivity of such solid wastes. However, the selection and application of activators often struggle to balance the relationship between activation and reaction process control. For example, while using a single strong alkaline activator can rapidly raise the pH of the system and promote the depolymerization of the aluminosilicate network, it often leads to excessively vigorous hydration reactions, resulting in rapid setting of the slurry, severely impacting workability, and producing a hardened body with a loose structure that hinders later strength development. Conversely, insufficient activation results in extremely slow early strength development of the material, failing to meet engineering application requirements.

[0005] A more critical technical bottleneck lies in addressing the issue of volume stability in the later stages of hardening. The high content of f-CaO in the ash is a major potential source of expansion; its slow hydration reaction in the later stages of hardening causes volume expansion, leading to stress within the hardened body and ultimately causing cracking and damage. Simultaneously, if the large amount of sulfate in the system cannot react with the dissolved aluminum phase in a controllable manner in the early stages of hydration to form stable ettringite, it will also cause problems such as delayed ettringite formation, similarly posing a risk of volume instability in the later stages. Existing technical solutions often struggle to simultaneously address the interrelated issues of activity activation and stability control, resulting in unstable material properties, long-term safety risks, and significantly limiting the high-value resource utilization of high-calcium, high-sulfur circulating fluidized bed ash. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material and its preparation method, which solves the problem that high-calcium, high-sulfur circulating fluidized bed ash has poor volume stability in the later stage due to its low activity and uncontrollable hydration reaction process, making it difficult to use as a cementitious material on a large scale.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material, employing the following technical solution: A high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material is composed of the following components in parts by weight: 85-97 parts of high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture, 1-8 parts of siliceous active filler, and 2-10 parts of composite sulfate-alkali activator.

[0008] The high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture is composed of circulating fluidized bed fly ash, circulating fluidized bed bottom ash and granulated blast furnace slag, with a mass ratio of (10-80):(0-50):(20-40). The circulating fluidized bed fly ash contains 3%–10% f-CaO, 5%–13% SO3, and 12%–25% total CaO; the composite admixture has a specific surface area of ​​not less than 550 m². 2 / kg.

[0009] The silica active filler is silica ash, wherein the content of amorphous SiO2 is not less than 90%.

[0010] The composite sulfate-alkali activator is composed of an alkaline component, a sodium sulfate component, and desulfurized gypsum, with the following mass ratio: alkaline component: sodium sulfate component: desulfurized gypsum = (2-6):(0.5-3):(1-5); the desulfurized gypsum contains no less than 85% CaSO4·2H2O.

[0011] By employing the above technical solution, this invention constructs a reaction system based on the synergistic effect of endogenous activating components (f-CaO and sulfate in ash slag) and exogenous composite activators. Furthermore, highly active siliceous fillers are introduced for performance optimization, achieving efficient activation and stable control of the gelling properties of high-calcium and high-sulfur solid waste. Its core mechanism lies in the synergistic activation of alkali and sulfur and the phased, controllable generation of hydration products, as detailed below: Early and rapid establishment of the reaction environment: When the cementitious material comes into contact with water, the anhydrous sodium sulfate, which has the fastest dissolution rate in the composite activator, dissolves rapidly, providing a large amount of Na. + and SO4 2-Meanwhile, the f-CaO naturally present in the circulating fluidized bed fly ash and the alkaline components (such as calcium hydroxide) in the activator dissolve, rapidly raising the pH of the liquid phase to a strongly alkaline environment (pH>12).

[0012] Leaching of active components from solid waste: The strongly alkaline environment disrupts the silicon-oxygen tetrahedral and aluminum-oxygen tetrahedral network structures of the amorphous phase in granulated blast furnace slag glass and ash, namely breaking Si-O-Si, Al-O-Al and Si-O-Al bonds, causing active silicon-aluminum components to leach into the liquid phase in the form of ions or oligomers.

[0013] Initial formation and structural construction of hydration products: the dissolved active silica-alumina components and the large amount of Ca in the liquid phase 2+ and SO4 2- The reaction occurs, rapidly forming ettringite (AFt) and early-stage hydrated calcium silicate (CSH) gel. The needle-like crystals of ettringite interlock to form a preliminary framework structure, providing early strength to the material; the CSH gel fills the spaces between the framework.

[0014] The middle and late stages of hydration and structural densification: The desulfurized gypsum in the composite activator and the anhydrous calcium sulfate (such as type II anhydrite) in the ash residue have slow dissolution rates, and they continuously replenish SO4 to the liquid phase in the middle and late stages of hydration. 2- This avoids the early SO4 2- The rapid consumption of aluminum phase, which could lead to phase transformation or reaction stagnation, ensures the continued progress of the hydration reaction. Simultaneously, the highly reactive amorphous SiO2 in the silica fume undergoes a secondary hydration reaction with Ca(OH)2 under a strongly alkaline environment, generating more CSH gel. These subsequently generated CSH gels fill the pores formed earlier, further optimizing the pore structure and improving the interfacial bonding strength, thereby enhancing the material's later-stage strength and durability.

[0015] This multi-component, multi-stage synergistic effect not only fully stimulates the potential activity of solid waste, but also regulates the hydration reaction kinetics to ensure the early and healthy consumption of f-CaO in the system, avoiding the risk of volume expansion caused by later hydration, thereby obtaining a solid waste cementitious material with high strength, excellent workability and long-term volume stability.

[0016] Preferably, the f-CaO content in the circulating fluidized bed bottom slag is no more than 5%, and the SO3 content is no more than 10%; the glass content in the granulated blast furnace slag is no less than 85%, and the MgO content is 5% to 15%.

[0017] By adopting the above technical solution, limiting the chemical composition of the bottom slag can avoid introducing too many potential expansion sources, making it mainly serve as a silica-alumina supplement and skeleton material. The high glass content ensures that the slag has sufficient potential hydraulic activity, while an appropriate amount of MgO can participate in the formation of hydrated magnesium aluminate or hydrotalcite-like phases under alkaline activation, which helps to fill pores and further improve the compactness of the hardened body structure.

[0018] Preferably, the sulfate minerals in the circulating fluidized bed fly ash and / or circulating fluidized bed bottom ash include anhydrous calcium sulfate, particularly type II anhydrite.

[0019] By adopting the above technical solution, the type II anhydrite, which has a lower solubility than desulfurized gypsum, is used as an endogenous slow-release sulfur source. This, together with the fast-release sulfur source (anhydrous sodium sulfate) and the medium-fast-release sulfur source (desulfurized gypsum) in the activator, forms a multi-level sulfate release system, making the hydration reaction process more stable and complete.

[0020] Preferably, the purity and fineness of the activator components are controlled, wherein the effective Ca(OH)2 content in calcium hydroxide is not less than 90%; the purity of Na2SO4 in anhydrous sodium sulfate is not less than 95%; the desulfurized gypsum is dried at 50-60℃ before use until the moisture content does not exceed 5% and the residue on an 80μm sieve does not exceed 10%; and the calcium hydroxide is pretreated until the residue on an 80μm sieve does not exceed 15%.

[0021] By adopting the above technical solutions, the stability of the chemical activity and the uniformity of dispersion of each component of the activator are ensured. Low-temperature drying of the desulfurized gypsum prevents it from dehydrating into hemihydrate or anhydrous gypsum, avoiding the introduction of uncontrollable rapid-setting components. Fineness control of each component ensures uniform dispersion during mixing and subsequent hydration, resulting in more synchronized and complete reactions.

[0022] Secondly, this invention provides a method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material, employing the following technical solution: A method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material includes the following steps: Circulating fluidized bed fly ash, circulating fluidized bed bottom ash, and granulated blast furnace slag are mixed and ground in a mass ratio of (10–80):(0–50):(20–40) to obtain a product with a specific surface area of ​​not less than 550 m². 2 / kg of high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture; The alkaline component, sodium sulfate component, and desulfurized gypsum were mixed in a mass ratio of (2-6):(0.5-3):(1-5) to obtain a composite sulfate-alkali activator. The high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture, siliceous active filler, and composite sulfate-alkali activator are mixed to obtain the high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material.

[0023] By adopting the above-mentioned technical solution, especially the synergistic grinding of multiple solid waste raw materials, it is not merely a simple physical mixing and particle size reduction, but also a mechanochemical activation process. During the grinding process, intense extrusion, shearing, and impact create microscopic defects such as lattice distortion and chemical bond breakage on the particle surface and inside, increasing the surface energy and reactive sites of the particles. Simultaneously, this process achieves a uniform distribution of different components at the micron level, ensuring close contact between the active aluminosilicate components (from slag and bottom ash) and the endogenous alkali-sulfur components (from fly ash). This microscopic homogenization lays the foundation for a rapid and uniform hydration reaction during subsequent water addition and stirring, ensuring the stability and superior performance of the cementitious material—something that simple mechanical mixing cannot achieve.

[0024] Preferably, in preparing the composite admixture, the circulating fluidized bed furnace bottom slag and granulated blast furnace slag are first ground separately to a specific surface area of ​​not less than 400 m². 2 / kg, to obtain pre-ground furnace bottom ash and pre-ground slag; then, the circulating fluidized bed fly ash, the pre-ground furnace bottom ash and the pre-ground slag are mixed and co-ground.

[0025] By adopting the above technical solution, this two-step process of pre-grinding and co-grinding solves the problem of large differences in hardness and grindability among different raw materials. Slag and bottom ash have high hardness, while fly ash is relatively soft. If they are directly mixed and ground, the soft components are easily over-ground, while the hard components are not sufficiently ground. By first independently pre-grinding the hard components to achieve a certain fineness, and then co-grinding them with fly ash, grinding efficiency can be effectively improved, energy consumption reduced, and a composite admixture with a more reasonable particle size distribution and higher overall activity can be obtained.

[0026] Preferably, the temperature inside the mill during the co-milling process does not exceed 120°C, and the specific surface area of ​​the composite admixture after co-milling is not less than 600 m². 2 / kg, and the raw materials are dried before grinding.

[0027] By adopting the above technical solutions, controlling the temperature inside the mill can prevent partial hydration or mineral phase transformation of the material due to high temperatures, thus ensuring the activity of the final product. Increasing the specific surface area to a higher level further increases the contact area between the material and water, accelerating the hydration reaction rate, which is particularly beneficial for improving the early strength of the material. The drying treatment of the raw materials ensures the smoothness of the dry grinding process, preventing material adhesion and clogging of the grinding equipment.

[0028] Preferably, the mixing process of each component is controlled by time and equipment.

[0029] By adopting the above technical solution, using efficient mixing equipment and ensuring sufficient mixing time, it is ensured that the various powder components such as composite admixtures, silica fume and composite activators can achieve uniform distribution at both the macroscopic and microscopic levels in the final dry powder cementitious material product. This is a key process step to ensure stable product quality and consistent performance in field applications.

[0030] Thirdly, the present invention provides the application of the high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material, adopting the following technical solution: The high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material is used in building structural materials, precast components, road base materials or filling materials. When using it, water is added and stirred at a water-cement ratio of 0.28 to 0.42, and it can be mixed with aggregates.

[0031] By adopting the above technical solution, the cementitious material prepared by this invention has adjustable working and mechanical properties, which can meet the needs of different engineering fields. By adjusting the water-cement ratio, it is possible to prepare materials ranging from high-strength building structural materials (lower water-cement ratio) to road base stabilization materials that meet road performance requirements (higher water-cement ratio), thus broadening the resource utilization pathways of high-calcium and high-sulfur circulating fluidized bed ash and slag, and having significant economic and environmental benefits.

[0032] This invention provides a high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material and its preparation method. It has the following beneficial effects: 1. This invention utilizes a composite activator composed of an alkaline component, sodium sulfate, and desulfurized gypsum, leveraging the different dissolution rates of each component to effectively control the hydration reaction process of cementitious materials. Anhydrous sodium sulfate and f-CaO provide sulfate concentration and early high alkalinity to initiate the reaction, while the anhydrous calcium sulfate in the desulfurized gypsum and ash serves as a continuous source of sulfate in the middle and later stages, avoiding rapid setting due to excessively fast reaction or reaction stagnation due to ion depletion. This method ensures that the material has sufficient working time and can achieve a continuous and stable increase in mechanical properties.

[0033] 2. This invention combines a synergistic grinding process with a composite activation system, effectively solving the problem of late-stage volume stability in high-calcium, high-sulfur circulating fluidized bed ash. Synergistic grinding enhances the reactivity of f-CaO in the ash, while the controlled hydration environment promotes the full conversion of f-CaO into stable hydration products in the early stages of hydration. This process consumes potential expansion sources and forms a dense, hardened structure, inhibiting harmful volume expansion caused by late-stage f-CaO hydration or delayed ettringite formation, thus ensuring the long-term durability of the material.

[0034] 3. This invention employs a preparation method involving the co-grinding of multiple solid waste raw materials. Through mechanochemical action, it enhances the cementitious activity of low-activity materials such as granulated blast furnace slag and circulating fluidized bed ash. This process enables the uniform compounding of different components at the microscale, providing a foundation for subsequent efficient and uniform hydration reactions, and is a key process guarantee for achieving high-performance cementitious materials. Compared to simple physical mixing of components, the materials prepared by this method exhibit higher activity and superior final performance. Attached Figure Description

[0035] Figure 1 This is a schematic diagram showing the test results of the characteristic components of the main raw materials provided in the embodiments of the present invention.

[0036] Figure 2 A comparison chart of the hydration heat release rate and residual f-CaO content of different cementitious materials provided by the present invention.

[0037] Figure 3 A comparison chart of setting time and paste fluidity of different cementitious materials provided for this invention.

[0038] Figure 4 A comparison chart of the mechanical properties of different cementitious mortars provided by this invention.

[0039] Figure 5 A comparison chart of the volume stability test results of different cementitious materials provided by the present invention.

[0040] Figure 6 A schematic diagram of the road performance of the road base material prepared in Example 5 of the present invention. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Preparation Examples 1-6: Preparation Example 1: This preparation example provides a method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture A1, including the following steps: The circulating fluidized bed furnace bottom ash BA-1 was dried at 105℃ to a moisture content of 0.6%, and the granulated blast furnace slag S-1 was dried at 105℃ to a moisture content of 0.5%. The dried circulating fluidized bed bottom ash BA-1 was independently ground to a specific surface area of ​​420 m². 2 / kg, the dried granulated blast furnace slag S-1 is individually ground to a specific surface area of ​​450m². 2 / kg, respectively, to obtain pre-ground furnace bottom slag and pre-ground slag; The raw materials were weighed according to a dry basis mass ratio of FA-1 circulating fluidized bed fly ash, pre-ground furnace bottom ash, and pre-ground slag of 50:20:30, mixed, and then subjected to dry co-grinding using ball milling. The mill temperature was controlled at 95℃ during the grinding process, and the grinding was carried out until the specific surface area was 630 m². 2 / kg, to obtain high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A1.

[0043] Preparation Example 2: This preparation example provides a method for preparing high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture A2, including the following steps: The circulating fluidized bed furnace bottom slag BA-1 was dried at 105℃ to a moisture content of 0.7%, and the granulated blast furnace slag S-1 was dried at 105℃ to a moisture content of 0.5%. The dried circulating fluidized bed bottom ash BA-1 was independently ground to a specific surface area of ​​405 m². 2 / kg, the dried granulated blast furnace slag S-1 was individually ground to a specific surface area of ​​455m². 2 / kg, respectively, to obtain pre-ground furnace bottom slag and pre-ground slag; The raw materials were weighed according to a dry basis mass ratio of circulating fluidized bed fly ash FA-1, pre-ground furnace bottom ash, and pre-ground slag of 10:50:40, mixed, and then subjected to dry co-grinding using ball milling. The mill temperature was controlled at 98℃ during the grinding process, and the grinding was carried out until the specific surface area was 555 m². 2 / kg, to obtain high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A2.

[0044] Preparation Example 3: This preparation example provides a method for preparing high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture A3, including the following steps: Granulated blast furnace slag S-1 was dried at 105℃ to a moisture content of 0.5%, and the dried granulated blast furnace slag S-1 was individually ground to a specific surface area of ​​460 m². 2 / kg, to obtain pre-ground slag; Circulating fluidized bed fly ash FA-1 and pre-ground slag were weighed according to a dry basis mass ratio of 80:20 (excluding circulating fluidized bed bottom ash). The mixture was then subjected to dry co-milling using ball milling, with the mill temperature controlled at 102℃, until a specific surface area of ​​560 m² was achieved. 2 / kg, to obtain high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A3.

[0045] Preparation Example 4: This preparation example provides a method for preparing composite sulfate-base activator B1, including the following steps: Desulfurized gypsum DG-1 was dried at 55℃ to a moisture content of 3.2% and then ground to a residue of 6.8% on an 80μm sieve; calcium hydroxide CH-1 was sieved to a residue of 6.5% on an 80μm sieve. Weigh each raw material according to the dry basis mass ratio of calcium hydroxide CH-1, anhydrous sodium sulfate NS-1, and desulfurized gypsum DG-1 of 4:1.5:2.5, place them in a horizontal ribbon mixer, and mix at a speed of 20 r / min for 15 min to obtain composite sulfate-alkali activator B1.

[0046] Preparation Example 5: This preparation example provides a method for preparing composite sulfate-base activator B2, including the following steps: The desulfurized gypsum DG-1 was dried at 55℃ to a moisture content of 3.0% and then ground until the residue on an 80μm sieve was 7.0%. Calcium hydroxide CH-1 was sieved until the residue on an 80μm sieve was 6.5%. The raw materials were weighed according to the dry basis mass ratio of calcium hydroxide CH-1, anhydrous sodium sulfate NS-1, and desulfurized gypsum DG-1 of 2:0.5:1, and placed in a horizontal ribbon mixer. They were mixed at a speed of 20r / min for 15min to obtain composite sulfate-alkali activator B2.

[0047] Preparation Example 6: This preparation example provides a method for preparing the composite sulfate-base activator B3, including the following steps: Desulfurized gypsum DG-1 was dried at 55℃ to a moisture content of 3.1% and ground until the residue on an 80μm sieve was 6.6%. Calcium hydroxide CH-1 was sieved until the residue on an 80μm sieve was 6.5%. The raw materials were weighed according to the dry basis mass ratio of calcium hydroxide CH-1, anhydrous sodium sulfate NS-1, and desulfurized gypsum DG-1 of 6:3:5, and placed in a horizontal ribbon mixer. The mixture was mixed at a speed of 25r / min for 18min to obtain composite sulfate-alkali activator B3.

[0048] Examples 1-5: Example 1: This embodiment provides a method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material, including the following steps: Based on dry weight, weigh 92 parts of the high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A1 obtained in Preparation Example 1, 4 parts of silica fume SF-1, and 4 parts of the composite sulfate-alkali activator B1 obtained in Preparation Example 4. The high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A1, silica fume SF-1 and composite sulfate-alkali activator B1 are added to a horizontal ribbon mixer and mixed at a speed of 20 r / min for 15 min to obtain a high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material. When using the high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material, add water at a water-cement ratio of 0.33, and use a planetary mixer to stir. First, stir at a low speed of 70 r / min for 3 minutes, and then stir at a high speed of 130 r / min for 3 minutes. After molding, cure at a temperature of 20℃ and a relative humidity of not less than 95%.

[0049] Example 2: This embodiment provides a method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material, including the following steps: Based on dry weight, weigh 97 parts of the high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A2 obtained in Preparation Example 2, 1 part of silica fume SF-1, and 2 parts of the composite sulfate-alkali activator B2 obtained in Preparation Example 5. The high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A2, silica fume SF-1 and composite sulfate-alkali activator B2 are added to a horizontal ribbon mixer and mixed at a speed of 20 r / min for 12 min to obtain a high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material. When using the high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material, add water at a water-cement ratio of 0.35, and use a planetary mixer to stir. First, stir at a low speed of 70 r / min for 2 minutes, and then stir at a high speed of 130 r / min for 3 minutes. After molding, cure at a temperature of 20℃ and a relative humidity of not less than 95%.

[0050] Example 3: This embodiment provides a method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material, including the following steps: Based on dry weight, weigh 90 parts of the high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A3 obtained in Preparation Example 3, 5 parts of silica fume SF-1, and 5 parts of the composite sulfate-alkali activator B1 obtained in Preparation Example 4. The high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A3, silica fume SF-1 and composite sulfate-alkali activator B1 are added to a horizontal ribbon mixer and mixed at a speed of 20 r / min for 15 min to obtain a high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material. When using the high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material, add water at a water-cement ratio of 0.36, and use a planetary mixer to stir. First, stir at a low speed of 70 r / min for 3 minutes, and then stir at a high speed of 130 r / min for 3 minutes. After molding, cure at a temperature of 20℃ and a relative humidity of not less than 95%.

[0051] Example 4: This example provides a method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material, including the following steps: Based on dry weight, weigh 85 parts of the high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A1 obtained in Preparation Example 1, 8 parts of silica fume SF-1, and 7 parts of the composite sulfate-alkali activator B3 obtained in Preparation Example 6. The high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A1, silica fume SF-1 and composite sulfate-alkali activator B3 were added to a double cone mixer and mixed at a speed of 20 r / min for 15 min to obtain a high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material. When using the high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material, add water at a water-cement ratio of 0.30, and mix with a planetary mixer. First, mix at a low speed of 70 r / min for 2 minutes, then mix at a high speed of 150 r / min for 2 minutes. After molding, cure at a temperature of 20℃ and a relative humidity of not less than 95%.

[0052] Example 5: This embodiment provides a method for preparing a high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material for road base materials, including the following steps: Based on dry weight, weigh 88 parts of the high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A2 obtained in Preparation Example 2, 2 parts of silica fume SF-1, and 10 parts of the composite sulfate-alkali activator B3 obtained in Preparation Example 6. The high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A2, silica fume SF-1 and composite sulfate-alkali activator B3 were added to a horizontal ribbon mixer and mixed at a speed of 25 r / min for 18 min to obtain a high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material for road base materials. When using the high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material for road base materials, water is added at a water-cement ratio of 0.40, and the mixture is mixed with graded crushed stone to prepare the road base materials, wherein the mass ratio of the high-calcium and high-sulfur circulating fluidized bed ash-based solid waste cementitious material to the graded crushed stone is 5:95. When mixing, first stir at a low speed of 70r / min for 3 minutes, then stir at a high speed of 130r / min for 3 minutes. After molding, cure at a temperature of 20℃ and a relative humidity of not less than 95%.

[0053] Comparative Examples 1-8: Comparative Example 1: Compared with Example 1, the difference is that the composite sulfate-alkali activator B1 is not added, the amount of high calcium and high sulfur circulating fluidized bed ash-based composite admixture A1 is adjusted to 96 parts, the amount of silica fume SF-1 is still 4 parts, and the rest are the same.

[0054] Comparative Example 2: Compared with Example 1, the difference is that silica fume SF-1 is not added, the amount of high calcium and high sulfur circulating fluidized bed ash-based composite admixture A1 is adjusted to 96 parts, the amount of composite sulfate-alkali activator B1 is still 4 parts, and the rest are the same.

[0055] Comparative Example 3: Compared with Example 1, the difference is that the composite sulfate-base activator B1 is replaced with an equal mass of calcium hydroxide CH-1, and all other aspects are the same.

[0056] Comparative Example 4: Compared with Example 1, the difference is that the composite sulfate-base activator B1 is replaced with an equal mass of anhydrous sodium sulfate NS-1, and all other aspects are the same.

[0057] Comparative Example 5: Compared with Example 1, the difference is that the composite sulfate-alkali activator B1 is replaced with an equal mass of desulfurized gypsum DG-1, and all other aspects are the same.

[0058] Comparative Example 6: Compared with Example 1, the difference is that the composite sulfate-alkali activator does not contain desulfurized gypsum DG-1, but is composed only of calcium hydroxide CH-1 and anhydrous sodium sulfate NS-1 in a dry basis mass ratio of 4:1.5, and the composite sulfate-alkali activator B1 is replaced by this binary activator in equal mass, and the rest are the same.

[0059] Comparative Example 7: Compared with Example 1, the difference lies in the preparation process of high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture A1. Circulating fluidized bed fly ash FA-1, pre-ground furnace bottom slag, and pre-ground slag are mixed and co-ground to a specific surface area of ​​480 m² / kg, which is lower than 550 m² / kg. All other aspects remain the same.

[0060] Comparative Example 8: Compared with Example 1, the difference is that after the circulating fluidized bed bottom ash BA-1 and granulated blast furnace slag S-1 are ground independently, they are not co-ground with circulating fluidized bed fly ash FA-1. Instead, circulating fluidized bed fly ash FA-1, pre-ground bottom ash and pre-ground slag are directly mechanically mixed to obtain a high-calcium and high-sulfur circulating fluidized bed ash-slag based composite admixture. All other aspects are the same.

[0061] Test Examples 1-6: Test Example 1: Test steps: Circulating fluidized bed fly ash FA-1, circulating fluidized bed bottom ash BA-1, granulated blast furnace slag S-1, silica fume SF-1, calcium hydroxide CH-1, anhydrous sodium sulfate NS-1, and desulfurized gypsum DG-1 were used as test samples. The circulating fluidized bed fly ash FA-1, circulating fluidized bed bottom ash BA-1, granulated blast furnace slag S-1, and silica fume SF-1 were dried to constant weight at 105℃, and the desulfurized gypsum DG-1 was dried to constant weight at 55℃.

[0062] The dried samples were ground and passed through a 75 μm sieve. The main oxide composition was determined by X-ray fluorescence spectroscopy, and the f-CaO content in circulating fluidized bed fly ash FA-1 and circulating fluidized bed bottom slag BA-1 was determined by the glycerol-ethanol method.

[0063] The main phase composition of each raw material was determined by X-ray diffraction, and the glass content of granulated blast furnace slag S-1 was determined by X-ray diffraction internal standard method.

[0064] Table 1. Test results of main components and characteristic components of raw materials

[0065] in conclusion: Figure 1 The table shows the test results of the main raw material characteristic components in Test Example 1. Based on the data in Table 1, and combined with Figures (a) and (b), it can be seen that the f-CaO content in the circulating fluidized bed fly ash FA-1 is 4.2%, the SO3 content is 8.87%, and the total CaO content is 18.83%, which meets the composition requirements of this invention for high-calcium, high-sulfur circulating fluidized bed fly ash. The f-CaO content in the circulating fluidized bed bottom ash BA-1 is 1.8%, and the SO3 content is 7.73%, lower than the corresponding levels in fly ash FA-1. This indicates that fly ash FA-1 mainly provides endogenous alkali and endogenous sulfate, while bottom ash BA-1 is mainly used to supplement silicon and aluminum components and improve the particle composition of the composite admixture.

[0066] According to the data in Table 1 and Figure (c), it can be seen that the glass content of granulated blast furnace slag S-1 is 94.2% and the MgO content is 10.13%, which has high potential hydraulic properties. It can release active silica-alumina components under composite sulfate-alkali activation conditions and participate in the formation of hydration products such as CSH gel and AFt.

[0067] Based on the data in Table 1 and Figure (d), it can be seen that the amorphous SiO2 content in silica fume SF-1 is 94.5%, the effective Ca(OH)2 content in calcium hydroxide CH-1 is 94.3%, the Na2SO4 content in anhydrous sodium sulfate NS-1 is 98.5%, and the CaSO4·2H2O content in desulfurized gypsum DG-1 is 92.0%. These raw materials can respectively provide an active silicon source, an exogenous alkali source, a rapid-release sulfur source, and a medium-rapid-release sulfur source, which, together with f-CaO in circulating fluidized bed fly ash FA-1 and type II anhydrite, constitute an alkali-sulfur synergistic activation system. This compositional basis supports the achievement of strength development and volume stability in subsequent embodiments of this invention.

[0068] Test Example 2: Experimental steps: Take 3.0g of each of the gelling materials prepared in Examples 1, 3, 4 and Comparative Examples 1, 4, 6, 7 and 8, add water according to the corresponding water-cement ratio, stir in a standard stirrer for 90s, and then quickly place in an isothermal calorimeter. Monitor the hydration heat release rate continuously for 72h at (20±0.02)℃, and record the time of appearance of the main heat release peak and the cumulative heat release over 72h.

[0069] Neat cement paste samples were prepared from the above-mentioned cementitious materials and cured under standard conditions for 3 days and 28 days. After crushing, core samples were taken, hydration was terminated with anhydrous ethanol, and the samples were dried and ground until all of them passed through an 80 μm square-hole sieve. The residual free calcium oxide (f-CaO) content in the samples was determined according to the ethylene glycol extraction method specified in GB / T176-2017 "Cement Chemical Analysis Methods".

[0070] Experimental data: Table 2. Hydration heat release characteristics and residual f-CaO content of different cementitious materials

[0071] in conclusion: Figure 2 (a) shows the changes in the hydration exothermic rate of each group of samples over 72 hours. The exothermic peaks of Examples 1, 3, and 4 appeared between 8 and 13 hours, and the peaks were full, indicating that the hydration reaction started in a timely manner and proceeded smoothly. This was due to the synergistic effect between the rapidly soluble anhydrous sodium sulfate and the slowly soluble calcium hydroxide and desulfurized gypsum in the composite sulfate-alkali activator, which enabled early alkalinity establishment and continuous sulfate supply.

[0072] In contrast, Comparative Example 1, without an activator, showed almost no significant exothermic reaction, indicating a severely delayed hydration process. Comparative Example 4, using only anhydrous sodium sulfate, and Comparative Example 6, lacking desulfurized gypsum, both exhibited exothermic peaks within 5 hours with sharp peak shapes, suggesting an overly vigorous reaction and a risk of poor performance due to instantaneous hydration. Comparative Example 7, with insufficient specific surface area, and Comparative Example 8, without co-milling, both showed delayed exothermic peaks with lower peak values, indicating insufficient overall reactivity of the materials.

[0073] Figure 2 (b) The residual free calcium oxide (f-CaO) content of each group of samples at 3d and 28d was visually compared. The f-CaO content of Examples 1, 3, and 4 decreased with age, and was below 1.0% at 28d. This is consistent with... Figure 2 (a) corresponds to the full and continuous hydration reaction. Synergistic grinding and composite activation jointly promote the formation of hydration products, providing a favorable physical space and chemical environment for the consumption of f-CaO, and effectively reducing the risk of volume expansion caused by the later hydration of f-CaO.

[0074] In contrast, the residual f-CaO content of each comparative example was at a high level (>1.7%) after 28 days. In particular, comparative example 1, which had the lowest reactivity, had almost no f-CaO consumed. Comparative examples 7 and 8 also had a large amount of residual f-CaO due to incomplete reaction. These factors pose potential risks to volume stability in the later stages.

[0075] In summary, regulating the hydration process with composite activators and enhancing the overall activity of the system through synergistic grinding are key to achieving controllable hydration reactions of high-calcium and high-sulfur circulating fluidized bed ash-based cementitious materials and effectively consuming f-CaO to ensure volume stability.

[0076] Test Example 3: Experimental steps: According to GB / T1346-2011 "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement", the standard consistency water requirement of each group of cementitious materials in Examples 1-4 and Comparative Examples 1-8 was determined using a Vicat apparatus, and the cement paste cone was sunk to a depth of (6±1) mm into the cement paste.

[0077] Neat cement paste was prepared under standard consistency water conditions, and the initial and final setting times of each group of cementitious materials were determined using a Vicat apparatus. Initial setting was defined as the needle penetrating (4±1) mm from the bottom plate, and final setting was defined as the needle penetrating no more than 0.5 mm into the cement paste.

[0078] According to the methods in GB / T8077-2012 "Concrete Admixtures", neat cement paste was prepared at the standard consistency water content of each group of cementitious materials, and its flowability was measured. The mixed neat cement paste was poured into a truncated conical mold, and its spread diameter was measured after the mold was lifted.

[0079] Experimental data: Table 3. Setting time and workability of different cementitious materials

[0080] in conclusion: Based on the data in Table 3 and Figure 3 The intuitive display allows for the analysis of the setting behavior and construction performance of different cementitious materials.

[0081] Figure 3 (a) and Figure 3 (b) The setting time and paste fluidity of each sample are shown. Examples 1-4 all exhibited moderate setting times, with initial setting times between 69-98 min and final setting times between 133-182 min, while their paste fluidity was all greater than 180 mm. This result indicates that the composite sulfate-alkali activator used in this invention, through the provision of early alkalinity by rapidly soluble anhydrous sodium sulfate, the maintenance of alkalinity by slowly soluble calcium hydroxide, and the adjustment of sulfate ion concentration by desulfurized gypsum, effectively controls the hydration reaction rate, ensuring both early reaction initiation and providing sufficient operational window for construction.

[0082] In contrast, the comparative examples revealed significant problems. The setting times of Comparative Example 1 (without activator) and Comparative Examples 3 and 5 (activated by a single weak base or sulfate) were all excessively long. Figure 3 In (a), the data points were significantly higher than those of other groups, indicating that its hydration activity was severely insufficient and could not meet the requirements of engineering applications. Comparative Example 4 (activated by single anhydrous sodium sulfate) and Comparative Example 6 (without desulfurized gypsum binary activator) showed rapid setting, with initial setting times within 15 minutes, and correspondingly the lowest paste fluidity. Figure 3 (b) indicates that activation by a single strong alkali salt leads to an excessively vigorous hydration reaction, causing the slurry to rapidly lose its fluidity. This, in turn, demonstrates the crucial role of desulfurized gypsum as a retarding component in the composite activator in inhibiting rapid setting and ensuring workability.

[0083] Furthermore, the setting time of Comparative Example 7 (insufficient specific surface area) and Comparative Example 8 (without co-milling) was longer than that of the Examples, and the fluidity was reduced. This indicates that the co-milling process improves the overall reactivity and homogeneity of the material, and is an important process guarantee for obtaining ideal setting properties. The fluidity of Comparative Example 2 (without silica fume) was slightly lower than that of Example 1, which also reflects the positive effect of silica fume on improving the performance of the system.

[0084] In summary, this invention effectively resolves the contradiction between the activation of activity and the controllability of the reaction process in high-calcium and high-sulfur solid waste systems through the synergistic design of composite activators and the synergistic grinding preparation process, thus obtaining a cementitious material with both reasonable setting time and excellent workability.

[0085] Test Example 4: Experimental steps: According to GB / T17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)", the mechanical properties of the cementitious materials prepared in Examples 1-4 and Comparative Examples 1-8 were tested.

[0086] The cement mortar was prepared using a standard cement mortar mixer with a mass ratio of cementitious material to standard sand of 1:3 and a water-cement ratio of 0.50.

[0087] The mixed mortar was filled into a triple mold measuring 40mm×40mm×160mm, compacted on a vibrating table, and then smoothed.

[0088] After curing in a curing chamber at (20±1)℃ and relative humidity of not less than 90% for 24 hours, the mold was demolded and then transferred to water at (20±1)℃ for further curing until 3 days, 7 days and 28 days of age.

[0089] After reaching the specified age, the specimens are removed and their flexural strength is tested using a flexural testing machine. Then, the two halves of the specimen that broke after flexural testing are placed on a compressive testing machine to test their compressive strength.

[0090] Experimental data: Table 4. Mechanical properties of mortars with different cementing materials

[0091] in conclusion: Based on the mechanical property data in Table 4 and Figure 4 The bar chart clearly shows the advantages of the cementitious material of this invention in terms of strength development.

[0092] like Figure 4 As shown in (a) and 4(b), the mortars of Examples 1-4 exhibited excellent flexural and compressive strength at 3d, 7d, and 28d, with a clear trend of strength increase. The compressive strength at 28d all exceeded 50MPa. This result is attributed to the synergistic activation effect of alkali and sulfur provided by the composite activator, which promoted the dissolution and subsequent reaction of active silica-alumina components in the circulating fluidized bed ash and slag, forming a large amount of ettringite (AFt) and hydrated calcium silicate (CSH) gel, constituting a dense hardened body structure. Simultaneously, the introduction of silica fume further optimized the pore structure through the micro-filling effect and secondary hydration reaction, significantly improving the later-stage strength.

[0093] The mechanical properties of the comparative example group lag far behind those of the example group, verifying the necessity of the key technical elements of the present invention. The strength of Comparative Example 1 (without activator) is low, indicating that the hydration activity of the solid waste system itself is limited and chemical activation must be carried out. In Comparative Examples 3, 4, 5, and 6, single or incomplete activators are used, and their strength development is not ideal. Especially in Comparative Examples 4 and 6, although the early reaction is intense (as shown in Test Example 3), an effective strength support structure cannot be formed, and the 28-day strength is much lower than that of Example 1, proving the key role of the synergistic effect of each component in the composite activator for the stable development of strength. Compared with Example 1, the 28-day strength of Comparative Example 2 (without silica fume) decreased by about 15%, highlighting the strengthening effect of silica fume on the system performance. The strengths of Comparative Example 7 (low specific surface area) and Comparative Example 8 (not co-ground) are also lower than that of Example 1, directly proving that improving the reaction activity of materials through co-grinding is an important prerequisite for achieving high strength.

[0094] In summary, the mechanical property test results show that co-grinding high-calcium and high-sulfur circulating fluidized bed ash and slag, and using a composite sulfate-alkali activator and silica fume for composite modification can effectively activate the cementitious activity of solid waste materials and prepare cementitious materials with excellent early and late mechanical properties.

[0095] Test Example 5: Experimental steps: According to GB / T1346-2011 "Test Methods for the Water Requirement of Normal Consistency, Setting Time and Soundness of Cement", the autoclave soundness of the cementitious materials in Examples 1-4 and Comparative Examples 1, 4, 6, 7, and 8 was determined by the Le Chatelier method. Prepare a standard consistency paste, fill the Le Chatelier mold, cure it, boil it, measure the increase in the distance between the pointers, and determine whether it is qualified.

[0096] According to GB / T750-1992 "Test Method for Autoclave Soundness of Cement", prepare a neat paste specimen of 25mm×25mm×280mm, measure the initial length after curing for 24h under standard conditions, then place it in an autoclave and cure it for 3h under a saturated steam pressure of 2.0MPa, measure the length again after cooling to room temperature, and calculate the autoclave expansion rate.

[0097] According to the relevant regulations of JC / T603-2004 "Test Method for Dry Shrinkage of Cement Mortar", prepare a neat paste specimen of 25mm×25mm×280mm, measure its initial length after standard curing for 3d, then move it to a constant temperature and humidity chamber at a temperature of (20±2)°C and a relative humidity of (50±4)%, and measure the length change rate at the ages of 28d and 90d respectively.

[0098] Experimental data: Table 5. Test results of volume soundness

[0099] in conclusion: Based on the data in Table 5 and Figure 5 The volume deformation results shown indicate that the cementitious material of the present invention has excellent volume stability.

[0100] Figure 5 (a) and Figure 5 (b) The autoclaving expansion rate and 90-day long-term length change rate of each sample are shown. The boiling stability test results of Examples 1-4 are all qualified, with autoclaving expansion rates all far below 0.5%, and the long-term length change showing only slight shrinkage, indicating that the system structure is stable after hardening. This is mainly attributed to the synergistic grinding process improving the reactivity of the ash residue, and the combined effect of the composite activator regulating the hydration process, allowing the free calcium oxide (f-CaO) in the system to fully participate in the hydration reaction in the early stage, generating stable hydration products, and avoiding the harmful volume expansion that occurs when it hydrates into Ca(OH)2 in the later stage.

[0101] Conversely, all comparative samples exhibited unsatisfactory volume stability under accelerated curing conditions such as boiling and autoclaving. The expansion in Comparative Example 1 (without activator) and Comparative Examples 7 and 8 (insufficient reactivity) stemmed from the delayed hydration of f-CaO. The expansion in Comparative Example 4 (single sodium sulfate) and Comparative Example 6 (without desulfurized gypsum) was even more pronounced, such as... Figure 5 As shown in (a), its autoclaving expansion rate is as high as 1.96%-2.85%. Its long-term length change rate ( Figure 5 (b) also changes from contraction to expansion. This is because the unbalanced activating effect leads to the uncontrolled formation of hydration products (especially ettringite), resulting in structural defects or delayed formation, which in turn triggers destructive internal stress.

[0102] In summary, the volume stability test results demonstrate that this invention effectively controls the hydration reaction kinetics of high-calcium and high-sulfur solid waste systems through the synergistic effect of synergistic grinding and composite activators, promotes the benign transformation of potential expanding phases such as f-CaO, and solves the risk of volume stability in the later stages of such materials.

[0103] Test Example 6: Experimental steps: According to JTGE51-2009 "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering", the cementitious material prepared in Example 5 was tested for its application performance in road base courses.

[0104] Based on the mass ratio of cementitious material to graded crushed stone of 5:95 as described in Example 5, the optimal moisture content of the mixture was determined to be 6.2%, and the maximum dry density was 2.28 g / cm³. 3 .

[0105] The cementitious material, graded crushed stone and water are mixed evenly in a mixer, and then formed in a cylindrical mold with a diameter of 150mm×150mm using the static pressing method, with the compaction degree controlled at 98%.

[0106] After molding, the specimens were demolded, grouped, and placed in a standard curing room at (20±2)℃ and relative humidity not less than 95% for curing.

[0107] One set of specimens was cured for 7 days, and the other set was cured for 28 days. After being removed, they were directly subjected to unconfined compressive strength testing.

[0108] Take another set of specimens cured for 27 days, immerse them in water at (20±1)℃ for 24 hours, remove them and wipe off the surface moisture, and then conduct an unconfined compressive strength test in water.

[0109] The formula for calculating the water stability coefficient is: ,in The water stability coefficient, The unconfined compressive strength after 28 days of immersion in water. The unconfined compressive strength after 28 days of standard curing.

[0110] Experimental data: Table 6. Performance test results of road base materials in Example 5

[0111] in conclusion: According to the data in Table 6, the cementitious material prepared in Example 5 exhibits excellent road performance when used in stabilized graded crushed stone. Its 7-day unconfined compressive strength reaches 3.8 MPa, and its 28-day strength increases to 6.2 MPa, meeting the strength requirements for cement-stabilized crushed stone base course materials under medium and heavy traffic levels in JTG / TF20-2015 "Technical Specifications for Construction of Highway Pavement Base Course".

[0112] Figure 6 The material's properties are visually demonstrated. Figure 6 (a) shows the strength development of the material from 7 days to 28 days, with a strength increase of more than 60%, indicating that the cementitious material has good late-stage hydration ability and can provide continuous strength support for road structures. Figure 6 (b) was used to evaluate the water stability of the material, comparing the strength after 28 days of standard curing with that after 24 hours of immersion in water. The strength after immersion was 5.4 MPa, and the strength retention rate, i.e., the water stability coefficient, was as high as 0.87, which is higher than the requirement in the specification that high-grade pavement base materials are usually not less than 0.80-0.85.

[0113] This superior performance stems from the dense microstructure formed after hydration of the cementitious material. Composite activation induces the formation of abundant CSH gel and ettringite in the ash and slag. These hydration products fill the pores of the aggregate skeleton, providing not only high strength but also reducing the interconnected porosity of the system. Therefore, the hardened base material exhibits strong water permeability resistance, maintaining structural integrity and most of its strength even under immersion conditions, thus ensuring the durability of the road base.

Claims

1. A high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material, characterized in that, It consists of the following components in parts by weight: 85-97 parts of high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture, 1-8 parts of siliceous active filler, and 2-10 parts of composite sulfate-alkali activator; The high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture is composed of circulating fluidized bed fly ash, circulating fluidized bed bottom ash and granulated blast furnace slag, with a mass ratio of (10-80):(0-50):(20-40). The circulating fluidized bed fly ash contains 3%–10% f-CaO, 5%–13% SO3, and 12%–25% total CaO. The specific surface area of ​​the composite admixture is not less than 550 m². 2 / kg; The silica-based active filler is silica fume, and the amorphous SiO2 content in the silica fume is not less than 90%. The composite sulfate-alkali activator is composed of an alkaline component, a sodium sulfate component, and desulfurized gypsum, with the following mass ratio: alkaline component: sodium sulfate component: desulfurized gypsum = (2-6):(0.5-3):(1-5); The desulfurized gypsum contains no less than 85% CaSO4·2H2O.

2. The high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material according to claim 1, characterized in that: The f-CaO content in the bottom ash of the circulating fluidized bed furnace does not exceed 5%, and the SO3 content does not exceed 10%. The granulated blast furnace slag contains no less than 85% glass, 5%–15% MgO, and has a specific surface area of ​​450–650 m². 2 / kg.

3. The high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material according to claim 1, characterized in that, The sulfate minerals in the circulating fluidized bed fly ash and / or circulating fluidized bed bottom ash include anhydrous calcium sulfate; The anhydrous calcium sulfate includes type II anhydrite.

4. The high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material according to claim 1, characterized in that, The alkaline component is calcium hydroxide, and the sodium sulfate component is anhydrous sodium sulfate; The effective Ca(OH)2 content in the calcium hydroxide is not less than 90%; The purity of Na2SO4 in the anhydrous sodium sulfate is not less than 95%; The desulfurized gypsum is dried at 50-60℃ before use until the moisture content does not exceed 5% and the residue on an 80μm sieve does not exceed 10%. The calcium hydroxide is pretreated by grinding or sieving until the residue on an 80μm sieve does not exceed 15%.

5. A method for preparing high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material, characterized in that, The preparation of the high-calcium, high-sulfur circulating fluidized bed ash-based all-solid waste cementitious material as described in any one of claims 1-4 comprises the following steps: The circulating fluidized bed fly ash, circulating fluidized bed bottom ash, and granulated blast furnace slag are mixed in the following mass ratio: Circulating fluidized bed fly ash: circulating fluidized bed bottom ash: granulated blast furnace slag = (10~80):(0~50):(20~40) The mixture is then ground to obtain a powder with a specific surface area of ​​not less than 550 m². 2 / kg of high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture; The alkaline component, sodium sulfate component, and desulfurized gypsum were mixed in the following mass ratio: Alkaline component: Sodium sulfate component: Desulfurized gypsum = (2-6): (0.5-3): (1-5) Mixing yields a composite sulfate-alkali activator; The high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture, siliceous active filler, and composite sulfate-alkali activator are mixed to obtain the high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material.

6. The preparation method according to claim 5, characterized in that, In preparing the high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture, the circulating fluidized bed bottom ash and granulated blast furnace slag are first separately ground to a specific surface area of ​​not less than 400 m². 2 / kg, to obtain pre-ground furnace bottom slag and pre-ground slag; The circulating fluidized bed fly ash, the pre-ground furnace bottom slag, and the pre-ground slag are then mixed and co-ground.

7. The preparation method according to claim 6, characterized in that, Both the independent grinding and the collaborative grinding are dry grinding methods, and the grinding method is ball milling or vertical milling. The temperature inside the mill during the synergistic grinding process does not exceed 120℃; The specific surface area of ​​the high-calcium, high-sulfur circulating fluidized bed ash-based composite admixture after co-grinding is not less than 600 m². 2 / kg; The circulating fluidized bed furnace bottom ash is dried at 100-110°C to a moisture content of no more than 1% before independent grinding. The granulated blast furnace slag is dried at 100-110°C to a moisture content of no more than 1% before being independently ground.

8. The preparation method according to claim 5, characterized in that, The mixing time of the composite sulfate-alkali activator shall not be less than 15 min; The mixing time of the high-calcium and high-sulfur circulating fluidized bed ash-based composite admixture, siliceous active filler, and composite sulfate-alkali activator shall not be less than 10 minutes. The mixing is performed using a V-type mixer, a double cone mixer, or a horizontal ribbon mixer, with a mixing speed of 15–30 r / min.

9. The application of the high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material according to any one of claims 1 to 4 in building structural materials, precast components, road base materials, or filling materials, characterized in that, When using the high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material, add water and stir at a water-cement ratio of 0.28 to 0.42; When used in building structural materials or prefabricated components, the water-cement ratio is 0.28 to 0.38; When used as a road base material, the water-cement ratio is 0.35–0.42; The building structure materials, prefabricated components, or road base materials include the high-calcium, high-sulfur circulating fluidized bed ash-based solid waste cementitious material, water, and aggregates.

Images