A desulfurized fly ash-containing cementitious building material and a preparation method and application thereof

Abstract

The application provides a desulfurization ash-containing cementitious building material and a preparation method and application thereof, belongs to the technical field of novel building materials, and the cementitious building material is modified desulfurization ash, modified blast furnace slag, modified desulfurization gypsum, calcium carbide slag powder, active calcium oxide, zeolite-based slow-release hydration regulator and composite volume stable densifying agent. The modified desulfurization ash is prepared by mixing desulfurization ash, calcined coal gangue powder and silica ash powder, adding water and sodium citrate, stirring, adding calcium nitrate tetrahydrate, manganese sulfate and hydrogen peroxide and stirring and reacting. The modified blast furnace slag is prepared by mixing blast furnace slag, sodium fluorosilicate and anhydrous sodium sulfate, spraying into a mixed solution of nano silicon dioxide sol and triethanolamine, drying, adding calcium stearate after ball milling and then drying. The zeolite-based slow-release hydration regulator is prepared by alkali hot activation of zeolite powder with sodium hydroxide, water washing and drying, immersing into a composite activation solution containing sodium silicate and sodium metaaluminate, suction filtration, drying and crushing. The modified desulfurization gypsum is prepared by drying, ball milling and adding sodium citrate.

Description

Technical Field

[0001] This invention pertains to the field of novel building materials technology, specifically relating to a desulfurized ash-containing cementitious building material, its preparation method, and its application. Background Technology

[0002] Cement, as the core cementitious material in civil engineering, is used in almost all construction scenarios, including building construction, roadbeds, site hardening, tailings solidification, and municipal subgrades. However, the production of silicate cement clinker requires high-temperature calcination of limestone and clay raw materials, resulting in extremely high energy consumption and large emissions of carbon, dust, and nitrogen oxides. Cement production costs are rising year by year, placing immense pressure on the industry to reduce carbon emissions and pollution. Meanwhile, the metallurgical, coal chemical, and thermal power industries generate tens of millions of tons of industrial solid waste annually. Slag, desulfurization gypsum, desulfurization ash, and carbide slag are stored and landfilled in the open, significantly encroaching on land resources. Developing clinker-free or low-clinker cementitious materials by compounding various types of industrial waste is a mainstream research direction for replacing traditional cement and achieving solid waste disposal and low-carbon production.

[0003] Existing solid waste-based cementitious materials suffer from several insurmountable technical defects. Currently, most desulfurized ash-based building materials only use desulfurized gypsum as an activating component, directly adding it to the desulfurized ash. The free calcium oxide inside the desulfurized ash expands and cracks when it comes into contact with water, and the activity of calcium sulfite is unstable, which easily leads to poor volume stability of the hardened paste. This results in cracking, efflorescence, and strength reduction in the later stages of the product, making it impossible to directly mix and use on a large scale. Common slag-based cementitious formulas on the market have a single slag ratio, insufficient hydration of the slag glass, and low early compressive strength under normal temperature curing. If the standards for use as paving and backfill materials are to be met, cement clinker or high-temperature steam curing must be added, which significantly increases production costs and energy consumption, thus losing the low-carbon advantage.

[0004] Existing formulas for similar products have unreasonable component combinations, with broad ranges for the proportions of various solid wastes. Insufficient desulfurization ash content fails to adequately absorb large quantities of solid waste, while excessive content directly undermines the stability of the cementitious system, limiting the applicable scenarios. When used for iron tailings solidification, the cementitious material content is too high, significantly increasing project costs. Solidified components exhibit surface salt precipitation and whitening, frequent shrinkage cracks, and insufficient durability for outdoor applications. Furthermore, most traditional solid waste cementitious materials rely solely on the hydration reaction of a single component, lacking a multi-component synergistic activation mechanism. The hydration complementarity between slag, desulfurization ash, and carbide slag is insufficient, resulting in high porosity of hydration products, weak resistance to water erosion and wet-dry cycles, and susceptibility to pulverization and breakage during long-term outdoor service.

[0005] In summary, existing desulfurization ash-based cementitious building materials suffer from numerous shortcomings, including poor stability, low early strength, reliance on clinker and steam curing, uneven solid waste utilization, poor durability, and narrow applicability. Therefore, it is necessary to modify the material, design a scientific formula, optimize the ambient temperature preparation process, enhance hydration activity through a multi-element alkali activation system, address the stability defects of desulfurization ash, achieve adjustable strength without the need for external cement clinker, and perform ambient temperature and pressure molding. This approach can also absorb various industrial solid wastes, suppress efflorescence cracking, and balance low carbon and low cost with high mechanical strength and high durability. It aims to fill the technical gaps in existing solid waste-based cementitious building materials and adapt to various engineering applications such as roadbed filling, tailings solidification, precast blocks, and site hardening. Summary of the Invention

[0006] This invention addresses the numerous shortcomings of existing desulfurization ash-based cementitious building materials, including poor stability, low early strength, reliance on clinker and steam curing, uneven solid waste utilization, poor durability, and narrow applicability. It provides a desulfurization ash-containing cementitious building material, its preparation method, and its application. The method involves modifying desulfurization ash, blast furnace slag, and desulfurization gypsum to prepare a zeolite-based slow-release hydration regulator and a composite volume-stabilizing densifier. These are then combined with calcium carbide slag powder, activated calcium oxide, and powdered polycarboxylate superplasticizer to construct a synergistic and complementary hydration system based on multiple industrial solid wastes. This eliminates the need for silicate cement clinker and high-temperature steam curing, effectively reducing the high energy consumption and carbon emissions associated with cement clinker calcination. It can also handle large quantities of four types of stockpiled industrial solid waste: desulfurization ash, blast furnace slag, desulfurization gypsum, and calcium carbide slag, achieving low-carbon resource utilization of solid waste while improving performance. The specific technical solution is as follows:

[0007] A desulfurized ash-containing cementitious building material comprises the following raw materials in parts by weight: 45-50 parts modified desulfurized ash, 35-40 parts modified blast furnace slag, 8-10 parts modified desulfurized gypsum, 4-6 parts calcium carbide slag powder, 0.8-1.5 parts activated calcium oxide, 3-6 parts zeolite-based slow-release hydration regulator, 0.5-1.2 parts composite volume stabilizer, and 0.1-0.3 parts powdered polycarboxylate superplasticizer;

[0008] The modified desulfurization ash is composed of a mixture of desulfurization ash, calcined coal gangue powder, and silica fume powder, with the addition of water and sodium citrate, followed by stirring. Then, calcium nitrate tetrahydrate, manganese sulfate, and hydrogen peroxide are added and stirred to react the mixture. The mixture is then dried and pulverized to a specific surface area of ​​430 m². 2 / kg~490m 2 / kg was prepared;

[0009] The modified blast furnace slag is a mixture of blast furnace slag, sodium fluorosilicate, and anhydrous sodium sulfate, which is then atomized and sprayed into a mixture of nano-silica sol and triethanolamine. After drying and ball milling, calcium stearate is added and mixed evenly to obtain a product with a specific surface area of ​​650 m². 2 / kg~710m 2 / kg of product;

[0010] The zeolite-based slow-release hydration regulator is prepared by zeolite powder being activated by alkaline heat with sodium hydroxide, washed and dried with water, then immersed in a composite activation solution containing sodium silicate and sodium aluminate, filtered, dried, and pulverized until the specific surface area is >500 m². 2 / kg was prepared;

[0011] The modified desulfurized gypsum is desulfurized gypsum ball-milled to a specific surface area of ​​350 m² / g. 2 / kg~410m 2 / kg, mixed with sodium citrate to obtain the product.

[0012] In the aforementioned cementitious building materials, the modified desulfurized ash is prepared by mixing desulfurized ash, calcined coal gangue powder, and silica fume powder in a mass ratio of 100:(5-8):(7-10), adding water and 0.3%-0.5% sodium citrate (by weight of desulfurized ash), and stirring at 67℃-73℃. Then, while stirring at 55℃-60℃, 0.12%-0.18% calcium nitrate tetrahydrate (by weight of desulfurized ash), 0.05%-0.07% manganese sulfate (by weight of desulfurized ash), and 12%-18% hydrogen peroxide (by weight of desulfurized ash) are added sequentially, followed by stirring and reaction. The mixture is then dried and pulverized to a specific surface area of ​​430 m². 2 / kg~490m 2 / kg was prepared.

[0013] Furthermore, the preparation method of the modified desulfurization ash includes: mixing desulfurization ash, calcined coal gangue powder, and silica fume powder at a mass ratio of 100:(5-8):(7-10), adding water at a solid-liquid mass ratio of 1:(0.55-0.6), adding 0.3%-0.5% sodium citrate by weight of desulfurization ash, stirring to form a slurry, stirring at 67℃-73℃ for 2-3 hours, adding 0.12%-0.18% calcium nitrate tetrahydrate by weight of desulfurization ash, 0.05%-0.07% manganese sulfate by weight of desulfurization ash, and dropwise adding 12%-18% hydrogen peroxide by weight of desulfurization ash, stirring and reacting at 55℃-60℃ for 1.5-2 hours; drying, and pulverizing to a specific surface area of ​​430 m². 2 / kg~490m 2 / kg, to obtain modified desulfurization ash.

[0014] In the aforementioned cementitious building materials, the modified blast furnace slag is a mixture of blast furnace slag, sodium fluorosilicate, and anhydrous sodium sulfate in a mass ratio of 100:(0.3-0.5):(0.7-0.9). This mixture is atomized and sprayed with a mixture of 5%-7% nano-silica sol (by weight of blast furnace slag) and 0.12%-0.18% triethanolamine (by weight of blast furnace slag). After drying and ball milling, 0.12%-0.18% calcium stearate (by weight of blast furnace slag) is added and mixed uniformly at 60℃-70℃ to obtain a specific surface area of ​​650 m². 2 / kg~710m 2 / kg of product.

[0015] Furthermore, the preparation method of the modified blast furnace slag includes: mixing blast furnace slag, sodium fluorosilicate, and anhydrous sodium sulfate at a mass ratio of 100:(0.3-0.5):(0.7-0.9); atomizing and spraying a mixture of 5%-7% nano-silica sol (by weight of blast furnace slag) and 0.12%-0.18% triethanolamine (by weight of blast furnace slag); stirring; drying; ball milling; adding 0.12%-0.18% calcium stearate (by weight of blast furnace slag) while stirring; and mixing uniformly at 60℃-70℃ to obtain a specific surface area of ​​650 m². 2 / kg~710m 2 / kg of modified blast furnace slag.

[0016] In the above-mentioned method for preparing modified blast furnace slag, the blast furnace slag is passed through a 325-mesh or 400-mesh sieve; the nano-silica sol has a solid content of 15wt% to 20wt% and a pH of 9 to 10.

[0017] In the aforementioned cementitious building materials, the zeolite-based slow-release hydration regulator is prepared by zeolite powder being activated by alkaline heat with sodium hydroxide, washed and dried with water, then immersed in a composite activating solution containing sodium silicate and sodium aluminate at 45℃~55℃, filtered, dried, and pulverized until the specific surface area is >500m². 2 / kg was prepared.

[0018] Furthermore, the preparation method of the zeolite-based slow-release hydration regulator includes: mixing zeolite powder with 8wt%–12wt% NaOH aqueous solution at a solid-liquid mass ratio of 1:(3.5–4.5), stirring at 75℃–85℃ for 1.5h–2.5h; filtering, washing the solid phase with deionized water until the pH of the filtrate is <8.5, drying, and obtaining activated zeolite; immersing the activated zeolite in a composite activation solution at 45℃–55℃ for 1.5h–2h at a solid-liquid mass ratio of 1:(2.5–3.5), wherein the composite activation solution contains 18wt%–22wt% sodium silicate, 8wt%–12wt% sodium aluminate, and the remainder is pure water; filtration, drying the solid, and pulverizing to a specific surface area >500m². 2 / kg, yielding a zeolite-based slow-release hydration regulator.

[0019] In the aforementioned cementitious building materials, the modified desulfurized gypsum is desulfurized gypsum dried at 120℃~130℃ and ball-milled to a specific surface area of ​​350m². 2 / kg~410m 2 It is prepared by mixing 0.2% to 0.3% sodium citrate by weight of desulfurized gypsum per kg.

[0020] Furthermore, the preparation method of the modified desulfurized gypsum includes: drying the desulfurized gypsum at 120℃~130℃ for 2h~3h, and ball milling it to a specific surface area of ​​350m². 2 / kg~410m 2 / kg, add 0.2% to 0.3% sodium citrate by weight of desulfurized gypsum, mix well, and obtain modified desulfurized gypsum.

[0021] In the above-mentioned cementitious building materials, the composite volume-stabilizing densifier is a mixture of lightly calcined magnesium oxide, boric acid, and tartaric acid in a mass ratio of (5.5-6.5):(1.5-2.5):(1.5-2.5).

[0022] In the aforementioned cementitious building materials, the lightly calcined magnesium oxide has a specific surface area > 500 m². 2 / kg.

[0023] In the aforementioned cementitious building materials, the specific surface area of ​​the carbide slag powder is 400 m². 2 / kg~450m 2 / kg.

[0024] In the above-mentioned cementitious building materials, the total calcium oxide content of the active calcium oxide is ≥90%, the free calcium oxide content is ≥85wt%, the residue on a 200-mesh sieve is ≤5%, and the activity is ≥380mL.

[0025] The preparation method of the above-mentioned desulfurized ash-containing cementitious building material includes the following steps: according to the mass fraction of raw materials, zeolite-based slow-release hydration regulator, composite volume stabilizer, modified desulfurized ash, modified desulfurized gypsum, carbide slag powder, active calcium oxide, and powdered polycarboxylate superplasticizer are added sequentially to modified blast furnace slag under stirring. Each raw material is mixed after being added, and homogenized after all the raw materials are added. The uniformity deviation of the raw material components is less than 1.2%, and the cementitious building material is obtained.

[0026] The above-mentioned cementitious building materials are used for tailings solidification, mine backfilling, roadbed subbase, site hardening floor or precast non-fired block preparation.

[0027] The present invention provides a desulfurized ash-containing cementitious building material, its preparation method, and its application, the beneficial effects of which include:

[0028] I. The material of this invention relies on a synergistic and complementary hydration system constructed from diverse industrial solid wastes. It eliminates the need for silicate cement clinker and high-temperature steam curing, effectively reducing the high energy consumption and carbon emissions associated with cement clinker calcination. It can handle large quantities of four types of stockpiled industrial solid waste: desulfurization ash, blast furnace slag, desulfurization gypsum, and carbide slag, achieving low-carbon resource utilization of solid waste. Through the synergistic effect of multi-component modified raw materials and composite regulating agents, it effectively alleviates several inherent defects of traditional solid waste cementitious materials, such as the expansion of free calcium oxide in desulfurization ash, unstable activity of calcium sulfite, low activity of slag at room temperature, efflorescence and drying shrinkage of hardened bodies, and insufficient durability against dry and wet conditions and sulfate attack. The hydration system generates a continuous, dense, and low-porosity gel matrix, balancing mechanical strength and long-term volume stability, making it suitable for various outdoor open-air engineering scenarios, including tailings solidification, mine backfilling, roadbed subbase, site hardening, and non-fired blocks.

[0029] II. In the preparation of modified desulfurization ash, sodium citrate complexes calcium ions and is combined with medium-temperature stirring to pre-dissolve most of the free calcium oxide in the desulfurization ash. Combined with calcined coal gangue and silica fume active silica-alumina components, an aluminosilicate coating layer is formed on the surface of calcium particles, preventing continuous contact between moisture and the internal calcium phase, significantly alleviating the continuous hydration expansion stress in the later stages of hardening. The system incorporates manganese sulfate as an oxidation catalyst and calcium nitrate tetrahydrate to supplement calcium ions; the two work synergistically with hydrogen peroxide to complete the oxidation conversion of calcium sulfite. Sodium citrate in the system pre-complexes Ca... 2+ The buffer slurry pH is adjusted to a slightly alkaline range, reducing the original strong alkaline environment of the desulfurization ash and accelerating the ineffective decomposition of hydrogen peroxide, thus ensuring the oxidation and conversion efficiency of calcium sulfite. The calcium sulfate generated by oxidation provides sulfate components to the hydration system, stabilizes the formation of ettringite strength framework, significantly reduces the risk of secondary expansion caused by the later phase transformation of calcium sulfite, and improves the volume stability of the hardened body.

[0030] III. In the preparation of modified blast furnace slag, sodium fluorosilicate hydrolyzes and etches the silica-alumina glassy body of the slag, while anhydrous sulfate simultaneously provides sulfate ions, promoting the dissolution of silicon and aluminum ions inside the slag at room temperature and effectively enhancing the slag's hydration activity at room temperature. Nano-silica sol adheres to the surface of slag particles, providing CASH hydration heterogeneous nucleation sites. Milling with triethanolamine refines the slag particles, chelates and dissociates silica-alumina ions inside the slag glassy body, jointly increasing the total amount of reactive components in the system and accelerating the formation rate of low-calcium CASH gel. Calcium stearate forms a hydrophobic layer on the surface of slag particles, preventing the rapid formation of a dense hydration shell that seals the internal glassy body during the initial mixing stage, moderately extending the slag's continuous hydration cycle, and improving the overall hydration degree of the slag. The amount of calcium stearate must be strictly controlled within a limited range; if the amount is too high, the hydrophobic layer will significantly increase the water consumption for the standard consistency of the slurry and reduce the fluidity of the paste and mortar. The grinding fineness is limited to 650 μm. 2 / kg or more, relying on the high specific surface area to compensate for the insufficient etching depth of the glass body under low sodium fluorosilicate doping, and to balance the powder activity and the water demand of the slurry.

[0031] IV. In the preparation of zeolite-based slow-release hydration regulators, alkaline thermal activation opens the closed three-dimensional channels of natural zeolite, and water washing removes free strong alkali, preventing early flash coagulation of the slurry. Sodium silicate and sodium aluminate composite activating components loaded into the channels form an active reserve carrier, achieving a slow-release gradient of activating ions and alleviating the problems of concentrated exothermic release and early cracking caused by concentrated release of alkali components in the early stages of hydration. The porous zeolite framework can partially block capillary water transport channels, and in conjunction with the slow-release alkali components, reduces the migration of soluble alkali. Through a dual pathway of physical barrier and chemical alkali fixation, it effectively reduces the degree of surface alkali precipitation, smooths the temperature difference of hydration exothermic release, and reduces the probability of drying shrinkage microcracks.

[0032] 5. In modified desulfurized gypsum, sodium citrate complexes calcium ions to slow down the instantaneous dissolution rate of gypsum, thereby achieving a long-term and gradual supply of sulfate ions, maintaining the stable formation of ettringite throughout the entire hydration cycle, and avoiding the deterioration of the gel structure due to the lack of sulfur source in the later stage.

[0033] VI. In the composite volume stabilizer, lightly calcined magnesium oxide, boric acid, and tartaric acid are compounded solely through physical dry mixing. The high specific surface area of ​​the lightly calcined magnesium oxide causes slight expansion during hydration, compensating for chemical shrinkage during hydration and drying shrinkage, thus balancing the overall volume deformation of the hardened body. Within the system, boric acid, through magnesium ion complexation, can temporarily delay magnesium oxide hydration. Strict control of the lightly calcined magnesium oxide ratio is crucial to prevent excessive expansion and matrix cracking caused by the diminishing inhibitory effect of boric acid during the later stages of curing. Tartaric acid regulates the growth morphology of ettringite crystals, generating short, uniform columnar ettringite, optimizing the internal pore structure of the matrix, reducing the penetration channels of corrosive media, and improving structural integrity under wet-dry and freeze-thaw cycles. Detailed Implementation

[0034] The present invention will be further described below with reference to specific implementation examples, but the present invention is not limited to these embodiments.

[0035] Example 1

[0036] A desulfurized ash cementitious building material comprises the following raw materials in parts by weight: 47 parts modified desulfurized ash, 38 parts modified blast furnace slag, 9 parts modified desulfurized gypsum, 5 parts calcium carbide slag powder, 1.2 parts activated calcium oxide, 4.5 parts zeolite-based slow-release hydration regulator, 0.8 parts composite volume stabilizer, and 0.2 parts powdered polycarboxylate superplasticizer.

[0037] The preparation method of modified desulfurization ash includes: desulfurization ash (f-CaO=14wt%, CaSO3=28wt%), calcined coal gangue powder (specific surface area 614m²), and other ingredients. 2 / kg), silica fume (specific surface area 521m²) 2 Mix the desulfurization ash (kg) at a mass ratio of 100:6.5:8, add water to adjust the solid-liquid mass ratio to 1:0.58, add 0.4% sodium citrate (by weight of desulfurization ash), stir at 200 rpm for 10 min to form a slurry, heat to 67℃~73℃, stir at 200 rpm for 2.5 h; cool to 58℃, add 0.15% calcium nitrate tetrahydrate (by weight of desulfurization ash) and 0.06% manganese sulfate (by weight of desulfurization ash) sequentially while stirring, add 15% hydrogen peroxide (27.5 wt% by weight of desulfurization ash) dropwise over 40 min, stir at 200 rpm for 1.5 h at 55℃~60℃; dry with hot air at 45℃~55℃ until the moisture content is 0.8 wt%, and pulverize to a specific surface area of ​​465 m². 2 / kg, store in a sealed, moisture-proof container.

[0038] The preparation method of modified blast furnace slag includes: blast furnace slag (passed through a 400-mesh sieve), sodium fluorosilicate, and anhydrous sodium sulfate are mixed at a mass ratio of 100:0.4:0.8 at 80 r / min; a mixture of 6% nano-silica sol (nano-silica content 18wt%, particle size 10nm, pH 9.5) and 0.15% triethanolamine (by mass of blast furnace slag) is atomized and sprayed into the mixture; the mixture is stirred at 150 r / min for 10 min; dried at 45℃~55℃ to a moisture content of 0.6wt%; ball milled with corundum grinding balls of φ10mm:φ15mm:φ20mm=3:4:3 and a ball-to-material mass ratio of 7:1; ball milled at 35 r / min for 35 min; the grinding balls are then filtered out; 0.15% calcium stearate (by mass of slag) is added under stirring; the mixture is mixed at 65℃ for 12 min until homogeneous, forming a hydrophobic coating layer; the material is then discharged, yielding a specific surface area of ​​684 m². 2 / kg of modified blast furnace slag, sealed and moisture-proof.

[0039] The preparation method of the zeolite-based slow-release hydration regulator includes: zeolite powder (specific surface area 263m²) 2 (kg) and 10wt% NaOH aqueous solution were mixed at a solid-liquid mass ratio of 1:4 and stirred at 200r / min for 2h in a temperature range of 75℃~85℃; filtered, the solid phase was washed with deionized water until the pH of the filtrate was 7.2; dried with hot air in a temperature range of 75℃~85℃ to a moisture content of 0.8wt%, to obtain activated zeolite; the activated zeolite was immersed in a composite activation solution at 50℃ for 1.5h at a solid-liquid mass ratio of 1:3, the composite activation solution containing 20wt% sodium silicate, 10wt% sodium aluminate, and the remainder being pure water; excess immersion solution was recovered by vacuum filtration; the solid was dried in a temperature range of 55℃~65℃ to a moisture content of 0.9%, and pulverized to a specific surface area of ​​536m². 2 / kg, store in a sealed container away from light.

[0040] The preparation method of modified desulfurized gypsum includes: drying the desulfurized gypsum at a temperature range of 120℃~130℃ for 2.5h, and ball milling it to a specific surface area of ​​397m². 2 / kg, add 0.25% sodium citrate by weight of desulfurized gypsum, mix well, and store in a sealed container.

[0041] The composite volume stabilizer is lightly calcined magnesium oxide (magnesium oxide purity 95wt%, specific surface area 560m²). 2 A mixture of boric acid and tartaric acid in a mass ratio of 6:2:2 ( / kg).

[0042] Among them, the specific surface area of ​​calcium carbide slag powder is 420m². 2 / kg.

[0043] The active calcium oxide contains 94 wt% total calcium oxide, 86 wt% free calcium oxide, 5 wt% residue on a 200-mesh sieve, and 380 mL of activity.

[0044] The preparation method of the above-mentioned desulfurized ash-containing cementitious building material includes the following steps: according to the mass fraction of raw materials, zeolite-based slow-release hydration regulator, composite volume stabilizer, modified desulfurized ash, modified desulfurized gypsum, carbide slag powder, active calcium oxide, and powdered polycarboxylate superplasticizer are added sequentially to modified blast furnace slag under stirring at 40 r / min. Each raw material is mixed for 5 min after being added, and after all the raw materials are added, they are mixed and homogenized at 80 r / min. The uniformity deviation of the raw material components is less than 1.2%, and the cementitious building material with a moisture content of 0.7 wt% is obtained. It is then sealed and stored in a plastic film woven bag.

[0045] Example 2

[0046] A desulfurized ash cementitious building material comprises the following raw materials in parts by weight: 45 parts modified desulfurized ash, 40 parts modified blast furnace slag, 8 parts modified desulfurized gypsum, 6 parts calcium carbide slag powder, 0.8 parts activated calcium oxide, 6 parts zeolite-based slow-release hydration regulator, 0.5 parts composite volume stabilizer, and 0.3 parts powdered polycarboxylate superplasticizer.

[0047] The preparation method of modified desulfurization ash includes: desulfurization ash (f-CaO=10wt%, CaSO3=22wt%), calcined coal gangue powder (specific surface area 638m²), and other ingredients. 2 / kg), silica fume (specific surface area 529m²) 2 Mix (kg) at a mass ratio of 100:5:10, add water to adjust the solid-liquid mass ratio to 1:0.55, add 0.5% sodium citrate (by weight of desulfurization ash), stir at 150 r / min for 12 min to form a slurry, heat to 67℃~73℃, stir at 150 r / min for 3 h; cool to 55℃, add 0.18% calcium nitrate tetrahydrate (by weight of desulfurization ash) and 0.05% manganese sulfate (by weight of desulfurization ash) sequentially while stirring, add 18% hydrogen peroxide (27.5 wt% concentration) (by weight of desulfurization ash) dropwise over 30 min, stir at 150 r / min for 2 h at 55℃~60℃; dry with hot air at 45℃~55℃ until the moisture content is 0.6 wt%, and pulverize to a specific surface area of ​​490 m². 2 / kg, store in a sealed, moisture-proof container.

[0048] The preparation method of modified blast furnace slag includes: blast furnace slag (passing through a 325-mesh sieve), sodium fluorosilicate, and anhydrous sodium sulfate are mixed at a mass ratio of 100:0.3:0.9 at 60 r / min, and atomized into a mixture of 5% nano silica sol (nano silica content 20wt%, particle size 10nm, pH 9) and 0.18% triethanolamine by mass of blast furnace slag, and stirred at 120 r / min for 12 min; The material was dried at 45℃~55℃ until the moisture content reached 0.8wt%, then ball-milled. The corundum grinding balls were sized as follows: φ10mm:φ15mm:φ20mm = 3.5:4.2:3.5, with a ball-to-material mass ratio of 8:1. The material was ball-milled at 30 rpm for 40 minutes, and the grinding balls were filtered out. Then, 0.12% (by weight of slag) of calcium stearate was added under stirring, and the mixture was stirred at 70℃ for 10 minutes until homogeneous, forming a hydrophobic coating. The material was then discharged, yielding a specific surface area of ​​710 m². 2 / kg of modified blast furnace slag, sealed and moisture-proof.

[0049] The preparation method of the zeolite-based slow-release hydration regulator includes: zeolite powder (specific surface area 275m²) 2 (kg) and 8wt% NaOH aqueous solution were mixed at a solid-liquid mass ratio of 1:4.5 and stirred at 150 r / min for 2.5 h at 75℃~85℃; filtered, the solid phase was washed with deionized water until the pH of the filtrate was 6.8; dried with hot air at 75℃~85℃ to a moisture content of 0.7wt%, to obtain activated zeolite; the activated zeolite was immersed in a composite activation solution at 55℃ for 1.5 h at a solid-liquid mass ratio of 1:2.5, the composite activation solution containing 22wt% sodium silicate, 8wt% sodium aluminate, and the remainder being pure water; excess immersion solution was recovered by vacuum filtration; the solid was dried at 55℃~65℃ to a moisture content of 0.6%, and pulverized to a specific surface area of ​​520 m². 2 / kg, store in a sealed container away from light.

[0050] The preparation method of modified desulfurized gypsum includes: drying the desulfurized gypsum at a temperature range of 120℃~130℃ for 2 hours, and ball milling it to a specific surface area of ​​410m². 2 / kg, add 0.2% sodium citrate by weight of desulfurized gypsum, mix well, and store in a sealed container.

[0051] The composite volume stabilizer is lightly calcined magnesium oxide (magnesium oxide purity 96wt%, specific surface area 517m²). 2 A mixture of boric acid and tartaric acid in a mass ratio of 6.5:1.5:2.5 ( / kg).

[0052] Among them, the specific surface area of ​​calcium carbide slag powder is 400m². 2 / kg.

[0053] The active calcium oxide contains 92 wt% total calcium oxide, 87 wt% free calcium oxide, 3 wt% residue on a 200-mesh sieve, and 388 mL of activity.

[0054] The preparation method of the above-mentioned desulfurized ash-containing cementitious building material includes the following steps: according to the mass fraction of raw materials, zeolite-based slow-release hydration regulator, composite volume stabilizer, modified desulfurized ash, modified desulfurized gypsum, carbide slag powder, active calcium oxide, and powdered polycarboxylate superplasticizer are added sequentially to modified blast furnace slag under stirring at 35 r / min. Each raw material is mixed for 6 min after being added, and after all the raw materials are added, they are mixed and homogenized at 70 r / min. The uniformity deviation of the raw material components is less than 1.2%, and the cementitious building material with a moisture content of 0.9 wt% is obtained. It is then sealed and stored in a plastic film woven bag.

[0055] Example 3

[0056] A desulfurized ash-containing cementitious building material comprises the following raw materials in parts by weight: 50 parts modified desulfurized ash, 35 parts modified blast furnace slag, 10 parts modified desulfurized gypsum, 4 parts calcium carbide slag powder, 1.5 parts activated calcium oxide, 3 parts zeolite-based slow-release hydration regulator, 1.2 parts composite volume stabilizer, and 0.1 parts powdered polycarboxylate superplasticizer.

[0057] The preparation method of modified desulfurization ash includes: desulfurization ash (f-CaO=18wt%, CaSO3=35wt%), calcined coal gangue powder (specific surface area 630m²), and other ingredients. 2 / kg), silica fume (specific surface area 542m²) 2 Mix the desulfurization ash (calcium nitrate) at a mass ratio of 100:8:7, add water to adjust the solid-liquid mass ratio to 1:0.6, add 0.3% sodium citrate (by weight of desulfurization ash), stir at 250 rpm for 8 minutes to form a slurry, heat to 67℃~73℃, stir at 250 rpm for 2 hours; cool to 60℃, add 0.12% calcium nitrate tetrahydrate (by weight of desulfurization ash) and 0.07% manganese sulfate (by weight of desulfurization ash) sequentially while stirring, add 12% hydrogen peroxide (27.5 wt% concentration) (by weight of desulfurization ash) dropwise over 45 minutes, stir at 250 rpm for 1.5 hours at 55℃~60℃; dry with hot air at 45℃~55℃ until the moisture content is 0.7 wt%, and pulverize to a specific surface area of ​​430 m². 2 / kg, store in a sealed, moisture-proof container.

[0058] The preparation method of modified blast furnace slag includes: mixing blast furnace slag (passed through a 400-mesh sieve), sodium fluorosilicate, and anhydrous sodium sulfate at a mass ratio of 100:0.5:0.7 at 100 r / min; atomizing and spraying the mixture into a solution of 7% nano-silica sol (nano-silica content 15wt%, particle size 10nm, pH 10) and 0.12% triethanolamine (by mass of blast furnace slag); and stirring at 180 r / min for 8 min. The material was dried at 45℃~55℃ until the moisture content reached 0.7wt%, then ball-milled. The corundum grinding balls were sized as follows: φ10mm:φ15mm:φ20mm = 3.2:4.5:3.2, with a ball-to-material mass ratio of 6:1. The material was ball-milled at 40 rpm for 30 minutes, and the grinding balls were filtered out. Then, 0.18% (by weight of slag) of calcium stearate was added under stirring, and the mixture was stirred at 60℃ for 15 minutes until homogeneous, forming a hydrophobic coating. The material was then discharged, yielding a specific surface area of ​​650 m². 2 / kg of modified blast furnace slag, sealed and moisture-proof.

[0059] The preparation method of the zeolite-based slow-release hydration regulator includes: zeolite powder (specific surface area 281 m²) 2 (kg) and 12wt% NaOH aqueous solution were mixed at a solid-liquid mass ratio of 1:3.5 and stirred at 250 r / min for 1.5 h in a temperature range of 75℃~85℃; filtered, the solid phase was washed with deionized water until the pH of the filtrate was 8.2; dried with hot air in a temperature range of 75℃~85℃ to a moisture content of 0.8wt%, to obtain activated zeolite; the activated zeolite was immersed in a composite activation solution at 45℃ for 2 h at a solid-liquid mass ratio of 1:3.5, the composite activation solution containing 18wt% sodium silicate, 12wt% sodium aluminate, and the remainder being pure water; excess immersion solution was recovered by vacuum filtration; the solid was dried in a temperature range of 55℃~65℃ to a moisture content of 0.5%, and pulverized to a specific surface area of ​​511 m². 2 / kg, store in a sealed container away from light.

[0060] The preparation method of modified desulfurized gypsum includes: drying the desulfurized gypsum at a temperature range of 120℃~130℃ for 3 hours, and ball milling it to a specific surface area of ​​350m². 2 / kg, add 0.3% sodium citrate by weight of desulfurized gypsum, mix well, and store in a sealed container.

[0061] The composite volume stabilizer is lightly calcined magnesium oxide (magnesium oxide purity 97wt%, specific surface area 572m²). 2 A mixture of boric acid and tartaric acid in a mass ratio of 5.5:2.5:1.5 ( / kg).

[0062] Among them, the specific surface area of ​​calcium carbide slag powder is 450m². 2 / kg.

[0063] The active calcium oxide contains 90 wt% total calcium oxide, 85 wt% free calcium oxide, 4 wt% residue on a 200-mesh sieve, and 385 mL of activity.

[0064] The preparation method of the above-mentioned desulfurized ash-containing cementitious building material includes the following steps: according to the mass fraction of raw materials, zeolite-based slow-release hydration regulator, composite volume stabilizer, modified desulfurized ash, modified desulfurized gypsum, carbide slag powder, active calcium oxide, and powdered polycarboxylate superplasticizer are added sequentially to modified blast furnace slag under stirring at 45 r / min. Each raw material is mixed for 4 min after being added, and after all the raw materials are added, they are mixed and homogenized at 90 r / min. The uniformity deviation of the raw material components is less than 1.2%, and the cementitious building material with a moisture content of 1.0 wt% is obtained. It is then sealed and stored in a plastic film woven bag.

[0065] In the above embodiments, the modified desulfurization ash is a multi-mineral composite powder mixture containing CaSO3, CaSO4, Ca(OH)2, aluminosilicate, and complexed citrate, without a unified chemical structural formula. The modified blast furnace slag is a glassy mineral composite modified mixture, without a single chemical structural formula. The zeolite-based slow-release hydration regulator is a porous mineral-supported composite salt mixture containing activated zeolite channels loaded with sodium silicate and sodium aluminate, without a single chemical structural formula. The modified desulfurization gypsum is an inorganic salt composite powder.

[0066] In the above embodiments, the overall dosage of the composite volume stabilizing densifier is strictly controlled and must not exceed the upper limit; this is to avoid excessive hydration of magnesium oxide and expansion cracking caused by the failure of boric acid complexation in the later stage of curing.

[0067] In all the above embodiments, the ball milling fineness of the modified blast furnace slag is strictly controlled at 650 μm. 2 At a concentration of / kg or above, the high specific surface area increases the exposed area of ​​the glass body, compensating for the insufficient etching depth under low sodium fluorosilicate doping. Together with the long-term alkalinity provided by the subsequent modified desulfurization ash and carbide slag, it forms a dual activation system of acid etching and alkali activation.

[0068] Recommended usage of the desulfurized ash-containing cementitious building materials prepared in the above embodiments:

[0069] I. Selection of water-to-adhesive ratio for different scenarios:

[0070] 1. Tailings solidification, mine backfilling, and roadbed subbase: water-cement ratio 0.38–0.43; for tailings with high water absorption, the ratio can be relaxed to 0.40–0.45.

[0071] 2. Outdoor hardened flooring: water-cement ratio 0.31–0.35;

[0072] 3. Precast non-fired blocks: water-cement ratio 0.27-0.30;

[0073] Optional external admixture: 0.05% to 0.15% of polyether-modified silicone defoamer by weight of cementitious building materials.

[0074] The mixing water temperature is 15℃~35℃; the cementitious building materials are pre-dry mixed for 1min~2min, and then wet mixed for 2min~3min after adding water until the slurry is uniform.

[0075] II. Standard Maintenance System:

[0076] Ambient temperature 15℃~35℃:

[0077] 1. Static resting period: After molding and laminating, seal and moisturize for 4-6 hours, with relative humidity ≥90%;

[0078] 2. Hydration enhancement period (1 day to 7 days): Spray water 2 to 3 times a day, maintain the surface moisture content at 12wt% to 16wt%, and keep the ambient humidity at ≥85%;

[0079] 3. Maturation period (8 days to 28 days): Water once a day with a small amount of water, and maintain an ambient humidity of ≥70%.

[0080] The raw material sources and indicators involved in the above embodiments are as follows: Desulfurization ash comes from Lingshou County Fengheng Mineral Products Processing Plant, and its indicators are: f-CaO = 10%–18%, CaSO3 = 22%–35%. Calcined coal gangue powder comes from Lingshou County Jinyuan Mining Processing Plant, and its specific surface area is >600 m². 2 / kg. The silica fume is sourced from Lingshou County Bocai Mineral Products Processing Plant, and its specific surface area is >500m². 2 / kg. Sodium citrate is anhydrous sodium citrate, with a purity of ≥98%. Calcium nitrate tetrahydrate has a purity of ≥98%. Hydrogen peroxide concentration is 27.5wt%. Blast furnace slag is sourced from Lingshou County Boheng Mineral Products Trading Co., Ltd., grade S95, 325 mesh or 400 mesh. Sodium fluorosilicate (sodium hexafluorosilicate) has a purity of ≥98%. Anhydrous sodium sulfate has a purity of ≥98%. Nano-silica sol is sourced from Hangzhou Wanjing New Materials Co., Ltd., with a nano-silica content of 30wt%, particle size of 10nm, and pH 9-11; after dilution with water, a nano-silica sol with a concentration of 15wt%~20wt% is obtained, and the pH is adjusted to 9-10. If necessary, 0.1wt%~0.2wt% of nonionic surfactant is added as a dispersant to induce collision and agglomeration of nano-silica particles. Triethanolamine has a purity of ≥98%, liquid. Calcium stearate has a purity of ≥98%, powder. The zeolite powder is sourced from Lingshou County Pengkai Mineral Products Trading Co., Ltd. It is natural clinoptilolite powder with a specific surface area >250 m². 2 / kg. Sodium silicate is sourced from Shandong Jinyueyuan New Materials Co., Ltd. Sodium aluminate is sourced from Shandong Qiangsen Chemical Co., Ltd. Desulfurized gypsum is sourced from Luetu Fine Chemical (Hebei) Co., Ltd., in powder form. Lightly calcined magnesium oxide is sourced from Weifang Lihe Powder Technology Co., Ltd., with a magnesium oxide purity ≥95% and a specific surface area of ​​500m². 2 / kg or more. Boric acid is anhydrous boric acid with a purity of ≥98%. Tartaric acid is anhydrous tartaric acid with a purity of ≥98%. Calcium carbide slag powder is sourced from Lingshou County Suda Mineral Products Processing Plant, with a specific surface area of ​​400m². 2 / kg~450m 2 / kg, free calcium hydroxide content >80wt%, moisture content <1.0%. Activated calcium oxide is sourced from Jiangxi Huancheng New Materials Co., Ltd., with total calcium oxide content ≥90%, free calcium oxide content ≥85wt%, 200-mesh sieve residue ≤5%, and activity ≥380mL. Powdered polycarboxylate superplasticizer is sourced from Liaoning Kelong Fine Chemical Co., Ltd., R-209.

[0081] Comparative Example 1

[0082] The difference from Example 1 is that the modified desulfurization ash is changed to 35 parts and the modified blast furnace slag is changed to 50 parts.

[0083] Comparative Example 2

[0084] The difference from Example 1 is that the modified desulfurized gypsum is changed to 4 parts and the calcium carbide slag powder is changed to 10 parts.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that no zeolite-based slow-release hydration regulator is added.

[0087] Comparative Example 4

[0088] The difference from Example 1 is that the modified desulfurization ash is directly replaced by desulfurization ash.

[0089] Comparative Example 5

[0090] The difference from Example 1 is that the modified desulfurization ash preparation process omits the steps of "cooling down to 58°C, adding 0.15% of calcium nitrate tetrahydrate and 0.06% of manganese sulfate by weight of desulfurization ash in sequence under stirring, adding 15% of hydrogen peroxide (27.5 wt% concentration by weight of desulfurization ash) dropwise over 40 min at a uniform rate, and stirring at 200 r / min for 1.5 h in a temperature range of 55°C to 60°C".

[0091] Comparative Example 6

[0092] The difference from Example 1 is that the modified blast furnace slag is directly replaced by blast furnace slag.

[0093] Comparative Example 7

[0094] The difference from Example 1 is that sodium fluorosilicate and anhydrous sodium sulfate are not added in the preparation of modified blast furnace slag.

[0095] Comparative Example 8

[0096] The difference from Example 1 is that the zeolite-based slow-release hydration regulator is directly replaced by zeolite powder.

[0097] Comparative Example 9

[0098] Commercially available Conch PO42.5 ordinary Portland cement was used.

[0099] General test conditions:

[0100] Test environment: Standard ambient temperature 20±2℃, relative humidity ≥50%; this is the environment for mixing and molding operations. Humidity requirements for curing chambers and curing rooms shall be implemented separately.

[0101] Powder pretreatment: The gelled powder to be tested should be sealed and stored in a moisture-proof environment.

[0102] Mixing water: tap water, water temperature 20±2℃.

[0103] Standardized laboratory mixing process: Dry mix the powder for 2 minutes, then add water and wet mix for 3 minutes.

[0104] Standard maintenance procedures:

[0105] Static rest period: After molding, cover with film and let stand for 5 hours with relative humidity ≥90%;

[0106] Hydration enhancement period (1d to 7d): Spray water twice a day, maintain the surface moisture content of the specimen at 12wt% to 16wt%, and keep the ambient humidity at ≥85%;

[0107] During the compaction and maturation period (8 days to 28 days): provide a small amount of water once a day for maintenance, and maintain an ambient humidity of ≥70%.

[0108] Note: For wet-dry cycle, sulfate erosion resistance durability specimens, and tailings solidification unconfined compressive strength specimens, continuous curing shall be carried out in a standard curing room with a temperature of 20±2℃ and a relative humidity of not less than 95%, and the above-mentioned segmented moisturizing system shall not be implemented.

[0109] Uniform demolding time: 24h ± 0.5h after molding.

[0110] I. Standard consistency water consumption and setting time:

[0111] The test environment was 20±2℃, with a relative humidity ≥90% inside the humidity curing chamber. The standard consistency water requirement was determined (water-cement ratio was variable). Neat paste was prepared according to a uniform mixing process, poured into molds, and leveled. The test needle was allowed to sink freely into the paste; the water-cement ratio was adjusted until the needle sank to a depth of 6mm±1mm from the bottom plate. The corresponding water-cement ratio was recorded, which is the standard consistency water requirement. The average value of three parallel samples was taken. The setting time was determined (water-cement ratio fixed at the standard consistency water requirement). Neat paste was prepared according to the standard consistency water requirement ratio, poured into molds, covered, and allowed to stand. Initial setting time: the needle sank to a depth of 4mm±1mm from the bottom plate; the time was recorded. Final setting time: the needle sank to a depth ≤1mm; the time was recorded. The average value of three parallel samples was taken.

[0112] II. Flowability of Neat Paste:

[0113] The inner diameter of the top opening of the truncated cone mold is 36 mm, the inner diameter of the bottom opening is 60 mm, and the height is 60 mm. The water-cement ratio is 0.40. Neat slurry is prepared according to a standardized mixing process, poured into the mold, lifted vertically, and allowed to stand for 30 seconds. The diameters in two mutually perpendicular directions are measured, and the arithmetic mean is taken. The average value of three parallel samples is also taken.

[0114] III. Pulp Bleeding Rate:

[0115] The water-cement ratio of the sample was 0.40. Neat slurry was prepared according to a standardized mixing process, poured into a 5L volumetric hopper, compacted using a vibrating table, leveled, covered with a film, and allowed to stand for 1 hour. The surface water was then collected and weighed. Bleeding rate = (mass of bleeding water / total mass of water added during mixing) × 100%. The average value of three parallel samples was taken.

[0116] IV. Mortar Flowability:

[0117] Mortar mix ratio: cementitious material: ISO standard sand = 1:3 (mass ratio), water-cement ratio 0.40. Prepare the mortar according to standard method, load it into a truncated cone mold, lift it vertically, and start the jump table to complete 25 jumps. Take the average value of 3 parallel samples.

[0118] V. 28-day flexural and compressive strength:

[0119] Specimen specifications: 40mm×40mm×160mm standard mortar specimens. Mortar mix ratio: cementitious material: ISO standard sand = 1:3 (mass ratio); water-cement ratio 0.28. Molding: molding on a vibratory table, filled in two layers, each layer vibrated 60 times; a uniform standard curing system was implemented. Loading rate: flexural strength 50±5N / s; compressive strength 2400±100N / s. Parallel specimens exceeding the average value by ±10% were discarded; the average value was taken when there were no fewer than 6 remaining valid specimens.

[0120] VI. Unconfined compressive strength of solidified tailings:

[0121] The iron tailings used in the experiment were whole tailings from iron ore beneficiation, which were dried before use. Particle size characteristics: particles smaller than 0.075mm accounted for 45wt% to 50wt%, with an average particle size of 30μm to 80μm and continuous gradation. The main chemical composition (mass fraction) was: SiO2 70% to 78%, Al2O3 4% to 6%, Fe2O3 8% to 10%, CaO 1% to 4%, MgO 1% to 5%, with the remainder being potassium and sodium oxides and a small amount of impurities. It belongs to inert siliceous aluminum tailings raw materials.

[0122] Specimen specifications: φ50mm×50mm cylindrical specimens. Curing ratio: iron tailings: cementitious material = 100:12 (mass ratio), without adding ISO standard sand, water-cement ratio 0.42; static pressing molding, compaction degree ≥93%. Curing period 28 days, continuous curing in a standard curing room at 20±2℃ and relative humidity ≥95%. Parallel specimens exceeding the average value by ±10% were discarded; the average value was taken when at least 6 valid specimens remained.

[0123] VII. Drying Shrinkage Test:

[0124] Specimen specifications: 25mm×25mm×280mm mortar specimen. Mortar mix ratio: cementitious material: ISO standard sand = 1:3 (mass ratio); water-cement ratio 0.33. Molding: molding on a vibratory compaction table, filled in two layers, each layer vibrated 60 times. Specimens were demolded 24h±0.5h after molding, cured in water at 20℃±2℃ for 48h±1h, and then the initial reference length was measured; subsequently, they were transferred to a drying shrinkage environment at 20℃±2℃ and 50%±5% relative humidity; the specimen length was measured after 28 days. Drying shrinkage rate = (initial reference length − current specimen length) / initial reference length × 100%. Data exceeding ±10% of the average value were discarded, and the average of three valid parallel data was taken.

[0125] 8. Quantitative test of efflorescence area ratio:

[0126] Specimen: 70.7mm cubic mortar specimen; Mortar mix ratio: cementitious material: ISO standard sand = 1:3 (mass ratio); water-cement ratio 0.33. Molding: Molded on a vibratory table, filled in two layers, each layer vibrated 60 times. Standard curing for 7 days, followed by natural drying for 28 days. The exposed surface of the specimen was covered with a 1mm × 1mm grid, and the area of ​​the efflorescence region was counted. Efflorescence area ratio = (area of ​​efflorescence region / total surface area of ​​the specimen) × 100%. Data exceeding ±10% of the average were discarded, and the average of three valid parallel data points was taken.

[0127] IX. Durability test of 50 cycles of wet and dry water cycling:

[0128] Specimens: 40mm×40mm×160mm mortar specimens; mortar ratio: cementitious material: ISO standard sand = 1:3 (mass ratio); water-cement ratio 0.33; molding: vibratory compaction table molding, two layers, each layer vibrated 60 times. Standard curing (20±2℃, relative humidity ≥95%) for 28 days. Six specimens per group, three for baseline strength testing and three for post-cycle strength testing. Single cycle regime: immersion in clean water at 20℃±2℃ for 20h±0.5h, followed by hot air drying at 60℃±2℃ for 4h±0.5h; total 50 cycles. After 50 cycles, the compressive strength of the specimens was measured, the compressive strength retention rate was calculated, and the average of the valid data was taken.

[0129] 10. Resistance to sulfate dry-wet cycles:

[0130] Specimens: 40mm×40mm×160mm mortar specimens; mortar mix ratio: cementitious material: ISO standard sand = 1:3 (mass ratio); water-cement ratio 0.33. Molding: Molded on a vibratory table, filled in two layers, each layer vibrated 60 times. Standard curing (20±2℃, relative humidity ≥95%) for 28 days. Six specimens per group, three for baseline strength testing and three for post-cycle strength testing. Single cycle: Immersion in 5wt% sodium sulfate solution (pH controlled 6~8) for 16h±0.5h, drying at 80℃±2℃ for 6h±0.5h; total 30 cycles. Compressive strength was tested after 30 cycles. Corrosion resistance coefficient of compressive strength = (compressive strength of specimen after cyclic erosion / compressive strength of baseline specimen under standard curing at the same age) × 100%.

[0131] Table 1 Test Results

[0132]

[0133] Table 1 (continued) Test Results

[0134]

[0135] The above embodiments exhibit excellent overall performance, with 28-day mechanical and durability indicators approaching those of ordinary Portland cement (PO42.5). The system utilizes a synergistic hydration system formed by a compound of modified desulfurization ash, modified slag, modified desulfurization gypsum, and carbide slag powder, where the shortcomings of each solid waste component are mutually compensated: the active calcium component increases the alkalinity of the slurry, promoting the dissociation of the slag glass; the slag dissolves silica-alumina ions, which react with sulfate ions released from the gypsum to form ettringite and low-calcium CASH gel; the modified desulfurization ash, combined with manganese sulfate catalyst, fully oxidizes calcium sulfite to calcium sulfate, continuously replenishing the system with a long-term sulfur source; and the zeolite regulator slowly releases activating ions, balancing the early and late hydration rates, enabling the formation of a stable hydration system without the need for cement clinker, thus meeting engineering requirements.

[0136] In Comparative Example 1, the content of desulfurization ash was reduced while the proportion of slag increased. After the content of modified desulfurization ash was reduced, the supply of calcium source and long-term sulfate in the system was insufficient, the alkali activation buffering capacity decreased, and it was difficult to continuously dismantle the high-content slag aluminosilicate glass. Most of the slag was only used as inert micro-aggregate filler, and the amount of CASH gel and ettringite generated was significantly reduced. The proportion of interconnected pores in the matrix increased, the number of capillary water transport channels increased, and soluble alkali ions were more likely to migrate with water to the surface of the specimen and precipitate, resulting in an increase in the efflorescence area ratio. During the drying stage, the capillary shrinkage stress increased, and the drying shrinkage deformation increased. The corrosive medium quickly penetrated into the matrix through the interconnected pores, and the strength decreased under wet-dry cycles and sulfate corrosion.

[0137] In Comparative Example 2, the amount of desulfurized gypsum was reduced, while the amount of calcium carbide slag was excessive. The reduced amount of modified desulfurized gypsum limited the supply of sulfates to the system, decreased the formation of ettringite, and resulted in a lack of a framework phase to support the matrix strength. The generated CASH gel had a high calcium-to-silicon ratio, leading to decreased density and chemical stability. Excess calcium carbide slag introduced a large amount of free Ca(OH)₂, resulting in an excessively high concentration of calcium ions in the pore solution, which produced a common ion effect and inhibited the dissolution of silicon and aluminum ions from the slag. Excess calcium hydroxide crystallized directionally in the pores, forming weak interfacial zones, causing simultaneous deterioration in the mechanical strength, drying shrinkage, efflorescence, and durability of the specimens.

[0138] Comparative Example 3 lacked a zeolite-based slow-release hydration regulator. Without the zeolite slow-release carrier, the alkali-activated components and active silica-alumina ions dissolved rapidly in the initial mixing stage, quickly forming a dense hydration film on the surface of the unhydrated solid waste particles. This blocked the continuous dissolution of the internal glassy body, exhibiting characteristics of concentrated early hydration exothermic reaction and weak hydration reaction in the middle and later stages. The overall amount of hydration products generated was insufficient, the proportion of coarse pores in the matrix increased, capillary water migration channels were well-developed, drying shrinkage deformation and alkali blooming were exacerbated, and the strength retention rate decreased under dry and wet conditions and sulfate erosion.

[0139] In Comparative Example 4, unmodified virgin desulfurization ash was used directly. The virgin desulfurization ash contains a large amount of undigested free calcium oxide and unstable calcium sulfite; after hardening, the free calcium oxide continues to hydrate to form calcium hydroxide, generating expansion stress. When this stress exceeds the tensile strength of the matrix, a large number of microcracks are generated; calcium sulfite lacks a catalytic oxidation process and cannot be converted into stable calcium sulfate. During service, it slowly oxidizes to form calcium sulfate, and in-situ, ettringite is generated, causing secondary delayed expansion; the lack of an aluminosilicate coating layer to block moisture leads to concentrated and intense calcium ion hydration reactions; the particle interface lacks active gel bonding, resulting in a significant increase in matrix porosity, a significant decrease in mechanical strength, and comprehensive deterioration in drying shrinkage, efflorescence, and durability.

[0140] In Comparative Example 5, the desulfurization ash modification omitted the entire oxidation process. Without the oxidizing agent and optimized temperature system, the calcium sulfite oxidation conversion rate decreased significantly, making it difficult to fully convert into active calcium sulfate. Insufficient sulfate supply occurred during the initial hydration stage, resulting in low ettringite formation, slow gel matrix formation, and structural imbalance. A large amount of residual calcium sulfite remained inside the hardened matrix, gradually oxidizing to calcium sulfate during long-term outdoor service, precipitating ettringite and generating uncontrollable later-stage expansion stress. Repeated accumulation of internal stress under alternating wet and dry conditions and sulfate erosion made the matrix prone to internal micro-damage, leading to a significant decrease in durability.

[0141] In Comparative Example 6, raw blast furnace slag was used directly. The raw blast furnace slag had not undergone multiple modifications such as chemical etching, ultrafine grinding, dilution and dispersion of nano-silica sol spraying, and surface hydrophobic activation. The glassy Si-O chemical bonds were highly stable, and the dissolution rate of silicon and aluminum ions in the room temperature alkaline system was extremely low. It lacked the nucleation sites of nano-silica sol after dilution and dispersion and low-pressure atomization treatment, sulfate synergistic activation, and triethanolamine-assisted grinding and refining multiple activation mechanisms. The overall hydration degree of the slag was low, and most of it was only used as inert aggregate filler. The hydration gel had poor continuity, weak particle interface adhesion, and was prone to interface debonding under load and corrosive media.

[0142] In Comparative Example 7, slag modification was performed to remove sodium fluorosilicate and anhydrous sodium sulfate. The absence of sodium fluorosilicate prevented the hydrolytic etching of the slag's glassy silica-oxygen network, making it difficult to expose internal active silica-alumina sites. The absence of anhydrous sodium sulfate prevented the rapid combination of aluminum ions dissolved from the slag with sulfate ions to form ettringite, resulting in aluminum ion enrichment in the pore solution and an inhibitory effect, further reducing the continuous dissolution rate of the slag. Relying solely on the system's basic alkalinity to activate the slag significantly reduced ion dissolution efficiency, resulting in insufficient total formation of hydrated gel and ettringite, decreased matrix density, and simultaneous degradation of mechanical strength and durability.

[0143] In Comparative Example 8, native zeolite powder was used directly without activated loading of activators. Unactivated natural zeolite relies solely on physical adsorption to absorb mixing water. In the initial stage of mixing, a large amount of adsorbed free water reduces the effective water-cement ratio. After hardening, it slowly releases water to dilute the alkalinity of the pore solution, weakening the hydration activation power of the slag. The zeolite channels are not loaded with active components such as sodium silicate and sodium aluminate, and have no ability to regulate the slow release of alkaline ions. At the same time, the adsorption of free calcium ions on the zeolite surface consumes the raw materials for generating CASH gel, disrupts the ion balance of the system, exacerbates efflorescence and drying shrinkage defects, and reduces mechanical strength and durability simultaneously.

Claims

1. A building material containing desulfurized ash cementitious material, characterized in that, The cementitious building materials include the following raw materials in parts by weight: 45-50 parts modified desulfurization ash, 35-40 parts modified blast furnace slag, 8-10 parts modified desulfurization gypsum, 4-6 parts calcium carbide slag powder, 0.8-1.5 parts activated calcium oxide, 3-6 parts zeolite-based slow-release hydration regulator, 0.5-1.2 parts composite volume stabilizer, and 0.1-0.3 parts powdered polycarboxylate superplasticizer; The modified desulfurization ash is prepared by mixing desulfurization ash, calcined coal gangue powder, and silica fume powder, adding water and sodium citrate, stirring, adding calcium nitrate tetrahydrate, manganese sulfate, and hydrogen peroxide, stirring and reacting, drying, and pulverizing. The modified blast furnace slag is prepared by mixing blast furnace slag, sodium fluorosilicate, and anhydrous sodium sulfate, atomizing and spraying a mixture of nano-silica sol and triethanolamine, drying, ball milling, and then adding calcium stearate. The zeolite-based slow-release hydration regulator is prepared by zeolite powder being activated by sodium hydroxide alkaline heat, washed and dried, then immersed in a composite activating solution containing sodium silicate and sodium aluminate, filtered, dried, and pulverized. The modified desulfurization gypsum is prepared by ball milling desulfurization gypsum and mixing it with sodium citrate.

2. The desulfurized ash-containing cementitious building material according to claim 1, characterized in that, The modified desulfurization ash is made by mixing desulfurization ash, calcined coal gangue powder, and silica fume powder in a mass ratio of 100:(5-8):(7-10), adding water and 0.3%-0.5% sodium citrate (by weight of desulfurization ash), and stirring at 67℃-73℃. Then, while stirring at 55℃-60℃, 0.12%-0.18% calcium nitrate tetrahydrate (by weight of desulfurization ash), 0.05%-0.07% manganese sulfate (by weight of desulfurization ash), and 12%-18% hydrogen peroxide (by weight of desulfurization ash) are added sequentially, followed by stirring and reaction. The mixture is then dried and pulverized to a specific surface area of ​​430 m². 2 / kg~490m 2 / kg was prepared; The modified blast furnace slag is prepared by mixing blast furnace slag, sodium fluorosilicate, and anhydrous sodium sulfate in a mass ratio of 100:(0.3-0.5):(0.7-0.9). A mixture of 5%-7% nano-silica sol (by weight of blast furnace slag) and 0.12%-0.18% triethanolamine (by weight of blast furnace slag) is atomized and sprayed into the mixture. After drying and ball milling, 0.12%-0.18% calcium stearate (by weight of blast furnace slag) is added and mixed uniformly at 60℃-70℃ to obtain a specific surface area of ​​650 m². 2 / kg~710m 2 / kg of product; The zeolite-based slow-release hydration regulator is prepared by zeolite powder being activated by alkaline heat with sodium hydroxide, washed and dried with water, then immersed in a composite activation solution containing sodium silicate and sodium aluminate at 45℃~55℃, filtered, dried, and pulverized until the specific surface area is >500m². 2 / kg was prepared; The modified desulfurized gypsum is desulfurized gypsum ball-milled to a specific surface area of ​​350 m² / g. 2 / kg~410m 2 It is prepared by mixing 0.2% to 0.3% sodium citrate by weight of desulfurized gypsum per kg.

3. A desulfurized ash-containing cementitious building material according to claim 1 or 2, characterized in that, The preparation method of the modified desulfurization ash includes: mixing desulfurization ash, calcined coal gangue powder, and silica fume powder at a mass ratio of 100:(5-8):(7-10), adding water at a solid-liquid mass ratio of 1:(0.55-0.6), adding 0.3%-0.5% sodium citrate by weight of desulfurization ash, stirring to form a slurry, stirring at 67℃-73℃ for 2-3 hours, adding 0.12%-0.18% calcium nitrate tetrahydrate by weight of desulfurization ash, 0.05%-0.07% manganese sulfate by weight of desulfurization ash, and adding 12%-18% hydrogen peroxide by weight of desulfurization ash dropwise while stirring at 55℃-60℃ for 1.5-2 hours; drying and pulverizing to a specific surface area of ​​430 m². 2 / kg~490m 2 / kg, to obtain modified desulfurization ash.

4. A desulfurized ash-containing cementitious building material according to claim 1 or 2, characterized in that, The method for preparing the modified blast furnace slag includes: mixing blast furnace slag, sodium fluorosilicate, and anhydrous sodium sulfate at a mass ratio of 100:(0.3-0.5):(0.7-0.9); atomizing and spraying a mixture of 5%-7% nano-silica sol (by weight of blast furnace slag) and 0.12%-0.18% triethanolamine (by weight of blast furnace slag); stirring; drying; ball milling; adding 0.12%-0.18% calcium stearate (by weight of blast furnace slag) while stirring; and mixing evenly at 60℃-70℃ to obtain a specific surface area of ​​650 m². 2 / kg~710m 2 / kg of modified blast furnace slag.

5. A desulfurized ash-containing cementitious building material according to claim 4, characterized in that, The blast furnace slag is sieved through a 325-mesh or 400-mesh sieve; the nano-silica sol has a solid content of 15wt% to 20wt% and a pH of 9 to 10.

6. A desulfurized ash-containing cementitious building material according to claim 1 or 2, characterized in that, The preparation method of the zeolite-based slow-release hydration regulator includes: mixing zeolite powder with 8wt%–12wt% NaOH aqueous solution at a solid-liquid mass ratio of 1:(3.5–4.5), stirring at 75℃–85℃ for 1.5h–2.5h; filtering, washing the solid phase with deionized water until the pH of the filtrate is <8.5, drying, and obtaining activated zeolite; immersing the activated zeolite in a composite activation solution at 45℃–55℃ at a solid-liquid mass ratio of 1:(2.5–3.5) for 1.5h–2h, wherein the composite activation solution contains 18wt%–22wt% sodium silicate, 8wt%–12wt% sodium aluminate, and the remainder is pure water; filtration, drying the solid, and pulverizing to a specific surface area >500m². 2 / kg, yielding a zeolite-based slow-release hydration regulator.

7. A desulfurized ash-containing cementitious building material according to claim 1 or 2, characterized in that, The preparation method of the modified desulfurized gypsum includes: drying the desulfurized gypsum at 120℃~130℃ for 2h~3h, and ball milling it to a specific surface area of ​​350m². 2 / kg~410m 2 / kg, add 0.2% to 0.3% sodium citrate by weight of desulfurized gypsum, mix well, and obtain modified desulfurized gypsum.

8. A desulfurized ash-containing cementitious building material according to claim 1 or 2, characterized in that, The composite volume-stabilizing densifier is a mixture of light-burned magnesium oxide, boric acid, and tartaric acid in a mass ratio of (5.5–6.5):(1.5–2.5):(1.5–2.5); the specific surface area of ​​the light-burned magnesium oxide is >500 m². 2 / kg; the specific surface area of ​​the calcium carbide slag powder is 400m². 2 / kg~450m 2 / kg; the total calcium oxide content of the active calcium oxide is ≥90%, the free calcium oxide content is ≥85wt%, the residue on a 200-mesh sieve is ≤5%, and the activity is ≥380mL.

9. The method for preparing a desulfurized ash-containing cementitious building material according to claim 1, characterized in that, The process includes the following steps: According to the mass fractions of the raw materials, zeolite-based slow-release hydration regulator, composite volume stabilizer, modified desulfurization ash, modified desulfurization gypsum, carbide slag powder, active calcium oxide, and powdered polycarboxylate superplasticizer are added sequentially to the modified blast furnace slag under stirring. Each raw material is mixed after being added, and homogenized after all the raw materials are added. The uniformity deviation of the raw material components is less than 1.2%, thus obtaining the cementitious building material.

10. The application of a desulfurized ash-containing cementitious building material as described in claim 1, characterized in that, Cemented building materials are used for tailings solidification, mine backfilling, roadbed subbase, site hardening flooring, or precast non-fired block preparation.

Images