Crystalline porous zeolite carrier-based supported composite activator and preparation method of steel slag powder-fly ash cementing material

Abstract

The invention belongs to the technical field of building materials and solid waste resource utilization, and relates to a preparation method of a supported composite activator based on a crystalline porous zeolite carrier and a preparation method of a steel slag powder-fly ash cementing material. The supported composite activator comprises the following raw materials in parts by mass: 55-58 parts of crystalline modified zeolite, 12-14 parts of a nucleating accelerant, 9-11 parts of a function enhancer, 8-9 parts of sodium hydroxide and 35-37 parts of sodium silicate. According to the supported composite activator disclosed by the invention, more accurate excitation control and performance improvement are realized through the unique crystal structure and surface characteristics of zeolite, and meanwhile, a'carrier-nucleation-performance 'triple synergistic mechanism is formed by matching with the specially designed nucleation accelerant and function enhancer; the load type composite exciting agent can improve the strength of the cementing material, and meanwhile, the impact toughness and durability are remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of building materials and solid waste resource utilization technology, specifically relating to a method for preparing a supported composite activator based on a crystalline porous zeolite carrier and a steel slag powder-fly ash cementitious material. Background Technology

[0002] In the field of solid waste resource utilization, the large-scale utilization of steel slag and fly ash from industrial solid waste has always been a research hotspot. These materials contain abundant silicon and aluminum components and have the potential to prepare cementitious materials, but their activity is low, requiring effective activation methods. Traditional chemical activation methods mainly use strong alkali activation, but these methods suffer from problems such as difficulty in controlling the reaction process and the easy generation of structural defects.

[0003] In recent years, research on porous materials as activator carriers has gradually gained attention. Chinese patents CN114751662B, CN102627759B, and CN103657696B disclose technical solutions using attapulgite as a carrier, utilizing its natural porous structure to achieve the slow release of activators and the loading of peroxyphosphotungstic acid and aluminum compounds. However, attapulgite, as a natural mineral material, has significant shortcomings: First, it is an amorphous, layered clay, which, although possessing a certain adsorption capacity, has irregular pore distribution, poor performance reproducibility, and difficulty in precisely controlling loading and release; second, its specific surface area is limited (typically 100-300 m² / g), resulting in low drug loading; third, its long-term stability in strongly alkaline environments is questionable, and the performance of attapulgite from different origins varies considerably. Related research has also involved natural porous materials such as diatomaceous earth and bentonite, but these materials also suffer from irregular pore structures and difficulties in precisely controlling surface properties. Artificially synthesized mesoporous molecular sieves possess regular pore structures and superior performance. Related patents (CN102259012B) demonstrate that shape-selective catalysis can be achieved through processes such as rotational synthesis and seed-induced catalysis. However, their synthesis routes are complex and dependent on template agents and specialized processes. Furthermore, their extremely high cost limits their application in cost-sensitive bulk building materials. Zeolite, as a natural crystalline porous material, possesses unique advantages. Unlike the layered structure of attapulgite, zeolite has a regular three-dimensional pore system with uniform pore size, exhibiting a molecular sieving effect. In addition, zeolite possesses abundant ion exchange capacity and an adjustable silica-alumina ratio, making it uniquely promising as an activator support. Chinese patents (CN117046507B, CN1301152C) disclose the application of catalysts supported on regular pores directly using zeolite and on shaped zeolite after secondary modification. However, the aforementioned technologies are either costly total synthetic routes or secondary modifications of deeply processed zeolites, neither of which involve deep crystalline modification and functionalization design of abundant and inexpensive natural zeolite ore specifically for activator loading. This results in current natural zeolites still suffering from problems such as pore blockage and insufficient active sites in their original state, necessitating the development of effective and low-cost modification methods to fully utilize their carrier function. Summary of the Invention

[0004] To address the shortcomings of existing carrier materials in terms of pore structure regularity, release control precision, stability, and potential high costs, this invention utilizes natural clinoptilolite zeolite and employs a crystal modification process combining acid washing and programmed temperature-controlled calcination to create a highly efficient carrier suitable for activator loading. Leveraging its properties, a method for preparing a loaded composite activator based on a crystalline porous zeolite carrier and a steel slag powder-fly ash cementitious material is proposed. The loaded composite activator of this invention achieves more precise activation control and performance enhancement through the unique crystal structure and surface properties of zeolite. Simultaneously, it is combined with specifically designed nucleation promoters (sodium aluminate and lithium silicate) and functional enhancers (n-octyltriethoxysilane, sodium bentonite, and ultrafine slag powder) to form a triple synergistic mechanism of "carrier-nucleation-performance." The loaded composite activator significantly improves the impact toughness and durability of the cementitious material while enhancing its strength.

[0005] To achieve the above objectives, the present invention adopts the following technical solution.

[0006] A supported composite activator based on a crystalline porous zeolite carrier comprises the following raw materials in parts by weight: 55-58 parts of crystalline modified zeolite, 12-14 parts of nucleation promoter, 9-11 parts of functional enhancer, 8-9 parts of sodium hydroxide, and 35-37 parts of sodium silicate.

[0007] Furthermore, the preparation method of crystalline modified zeolite is as follows: natural clinoptilolite ore is crushed and ground to a fineness of 200 mesh or higher, then reacted with inorganic acid under heating conditions with stirring for 3-4 hours. After washing off the acid and drying, the zeolite is calcined in a muffle furnace with programmed temperature rise to obtain crystalline modified zeolite. The silica-alumina ratio of the crystalline modified zeolite is 4-6, and the specific surface area is ≥380 m². 2 / g.

[0008] Furthermore, the inorganic acid is 1-2 mol / L hydrochloric acid or nitric acid.

[0009] Furthermore, the heating temperature is 80-90℃.

[0010] Furthermore, the temperature is increased to between 450°C and 550°C and held for 2-4 hours.

[0011] Furthermore, the nucleation promoter is composed of sodium aluminate and lithium silicate.

[0012] Furthermore, the functional enhancer is composed of n-octyltriethoxysilane, sodium bentonite, and ultrafine slag powder.

[0013] Furthermore, sodium aluminate is an industrial-grade solid powder with a purity of ≥95%.

[0014] Furthermore, lithium silicate is an industrial-grade solid powder, whose main component is lithium silicate with a purity of ≥90%.

[0015] Furthermore, n-octyltriethoxysilane is an industrial-grade colorless and transparent liquid with a liquid main component content of ≥97%.

[0016] Furthermore, sodium-based bentonite is a solid powder with a montmorillonite content ≥85% and an expansion capacity ≥15 mL / g.

[0017] Furthermore, the ultrafine slag powder is a powder made by grinding granulated blast furnace slag, with a specific surface area of ​​not less than 550 m². 2 / kg.

[0018] Furthermore, sodium hydroxide is a solid powder with a solid content greater than 96%.

[0019] Furthermore, sodium silicate is a solid powder with a modulus (SiO2 / Na2O molar ratio) of 2.3.

[0020] The preparation method of the supported composite activator based on crystalline porous zeolite support includes the following steps: a. Add equal masses of water to sodium hydroxide and sodium silicate respectively and stir until homogeneous to prepare sodium hydroxide solution and sodium silicate solution. After the solution temperature is constant, mix the two solutions to obtain a basic activator solution with a modulus of 1.4-1.5. b. After pretreating the crystalline modified zeolite under vacuum conditions, it is injected in stages with an activation liquid containing nucleation promoters and functional enhancers, and impregnated under pressure in stages to obtain a wet intermediate. c. The wet intermediate is heat-treated to obtain a supported composite activator.

[0021] Furthermore, the crystalline modified zeolite is pretreated under vacuum conditions. The specific operating steps are as follows: After weighing the prepared crystalline modified zeolite, spread it evenly in a high-temperature resistant ceramic crucible or evaporating dish and place it in a vacuum drying oven; start the vacuum pump, evacuate the pressure inside the oven to -0.1 MPa, set the temperature to 110℃, and maintain this condition for 2-3 hours; after the heat treatment is completed, turn off the heating and allow the material to cool naturally to room temperature while maintaining the vacuum condition; the pretreatment is completed, and the pretreated crystalline modified zeolite carrier is obtained. Furthermore, the segmented pressure-maintaining impregnation process is divided into a low-pressure permeation stage and a normal-pressure adsorption and equilibrium stage, with the specific operating steps as follows: Low-pressure permeation stage: The pretreated crystalline modified zeolite is put into the impregnation tank, the tank is closed, and a vacuum is drawn to -0.1 MPa and maintained for 15 minutes. While maintaining this vacuum, the first impregnation solution, which is a mixture of nucleation promoter (sodium aluminate + lithium silicate) and 1 / 3 of the basic activator solution, is slowly injected. After the injection is completed, the vacuum valve is closed, nitrogen is introduced into the tank to a pressure of 0.5 MPa, and the tank is impregnated at room temperature (25±5℃) for 4 hours while intermittently stirring at a low speed (30 rpm) (on for 5 minutes, off for 25 minutes). Atmospheric pressure adsorption and equilibrium stage: Slowly release the pressure inside the tank to atmospheric pressure, open the feed port, add the functional enhancer (n-octyltriethoxysilane + sodium bentonite + ultrafine slag powder) and the remaining basic activator solution, close the feed port, and stir continuously at 60 rpm for 2 hours under atmospheric pressure and 40℃ conditions to ensure that the components are fully mixed and complete the final adsorption. Finally, the temperature was raised to 60°C, and the mixture was stirred at normal pressure for 1 hour. After impregnation, the slurry in the tank was discharged to obtain a wet intermediate.

[0022] Furthermore, the specific operation steps of heat treatment are as follows: The wet intermediate was evenly spread in a drying tray, with a thickness not exceeding 2 cm. The tray was placed in a drying oven and subjected to programmed temperature rise heat treatment in an air atmosphere. First, the temperature was increased from room temperature to 85°C at a rate of 2°C / min and held at 85±5°C for 8 hours. Then, the temperature was decreased to 50°C at a rate of 1°C / min and held for 2 hours. After the heat treatment, the heating power was turned off, the ventilation vents of the drying oven were opened, and the material was allowed to cool naturally to room temperature inside the oven. Finally, the dried block material was taken out, lightly crushed with a mortar and pestle or a small crusher, and passed through an 80-mesh (approximately 180μm) standard sieve to obtain a dry, uniform powdered supported composite activator, which was then sealed and packaged for later use.

[0023] A method for preparing a steel slag powder-fly ash cementitious material includes the following steps: a. Precursor preparation: Fly ash and steel slag powder are mixed at a mass ratio of 6:4~6.5:3.5 and ground together until the specific surface area is ≥500 m². 2 / kg, to obtain the precursor; b. Use of activator: Dissolve the supported composite activator in water and stir evenly, with the amount of water added so that the water-to-solid ratio is 0.3 (total water content / solid content of all solid powders including fly ash, steel slag powder and supported composite activator). c. Segmented mixing process: The first stage of mixing is a high-concentration premix. All the loaded composite activator solution and 1 / 3 of the total mass of the precursor are added to the mixing tank and stirred at low speed (140±5 rpm) for 2 minutes, and then stirred at high speed (285±10 rpm) for 3 minutes to form a uniform and thick slurry with a certain fluidity. The second stage of mixing is the final dilution mixing. Without stopping the machine as described above, the remaining 2 / 3 of the precursor is continuously added to the mixing tank. After all the precursor is added, the mixture is first stirred at a low speed (140±5 rpm) for 1 minute, and then stirred at a high speed (285±10 rpm) for 2 minutes until a gelling material slurry with uniform color and consistent texture is obtained. d. Molding and curing to obtain steel slag powder-fly ash cementitious material.

[0024] Furthermore, the steel slag powder has a mesh size ≥ 325 mesh and a specific surface area ≥ 400 m² / kg; its main chemical composition is CaO 35-50%, SiO2 10-20%, Fe2O3 15-25%, and Al2O3 5-10%. Furthermore, the fly ash is Grade I fly ash, with a specific surface area of ​​not less than 350 m² / kg and a loss on ignition of not more than 5%; its main chemical composition is SiO2 40-60%, Al2O3 20-30%, and CaO ≤ 10%.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0026] 1. Support Mechanism of Crystalline Modified Zeolite: Unlike the layered structure of attapulgite, clinoptilolite possesses a unique three-dimensional pore system, exhibiting advantages in crystal structure, surface property regulation, and ion exchange characteristics. The [SiO4] and [AlO4] tetrahedra of zeolite are connected by oxygen bridges to form a regular three-dimensional network structure with pore sizes between 0.4-0.7 nm, exhibiting a precise molecular sieving effect. This regular structure ensures the controllability and reproducibility of activator release, demonstrating the advantages of the crystal structure. By controlling the silicon-to-aluminum ratio within the range of 4-6, the acid-base distribution on the zeolite surface is optimized, enhancing the interaction with the activator components and regulating surface properties. Simultaneously, the heat treatment process (450-550℃) further optimizes the distribution and density of surface hydroxyl groups. Furthermore, the Al in the zeolite framework... 3+ Replace Si 4+ The negative charge generated is from Na + Equivalent equilibrium ion compensation allows these ions to exchange with cations in the excitation system, achieving a unique ion regulation function.

[0027] 2. Directional Guidance Mechanism of Nucleation Promoters: The combined use of sodium aluminate and lithium silicate produces a synergistic effect. Sodium aluminate provides an early aluminum source, promoting initial nucleation; lithium silicate, through the template effect of lithium ions, guides the gel growth along a specific direction, achieving precise control of the nucleation timing; furthermore, the presence of lithium ions promotes the formation of a denser gel network, improving the microstructure of the material. This enables the regulation of crystal growth.

[0028] 3. Synergistic Mechanism of Hydrophobic-Multi-Level Toughening in Functional Enhancers: The three components—n-octyltriethoxysilane, sodium bentonite, and ultrafine slag powder—work synergistically at different scales to enhance and toughen the material. At the nano / submicron scale, n-octyltriethoxysilane, through its long-chain alkyl groups, forms a robust hydrophobic film and physical adsorption layer on the surface of inorganic powders and hydration products, effectively optimizing interfacial compatibility, blocking moisture erosion, and reducing microcrack initiation, fundamentally improving the matrix's density and damage tolerance. At the micron scale, the layered structure of sodium bentonite dissipates fracture energy through crack deflection, bridging, and pull-out mechanisms. At the macroscopic scale, ultrafine slag powder optimizes particle size distribution, fills pores, and reduces stress concentration. These three components work synergistically to construct a multi-level defense system from nano-protection to macroscopic reinforcement, significantly enhancing the material's durability while improving toughness.

[0029] 4. Innovative Preparation Process and Synergistic Optimization Mechanism: Vacuum pretreatment of crystalline modified zeolite effectively removes adsorbed moisture and impurity gases from the zeolite channels, improving the adsorption capacity and impregnation uniformity of the carrier and preventing channel blockage or uneven distribution due to gas residue during subsequent impregnation. Impregnation is performed in two stages: first, nucleation promoters and part of the activation liquid are infiltrated under low pressure; then, functional enhancers and the remaining activation liquid are added under normal pressure. In the low-pressure stage, negative pressure is used to penetrate the small-molecule activation liquid deep into the zeolite micropores, achieving "pre-loading." In the normal-pressure stage, macromolecular or particulate components (such as bentonite and slag powder) are added to complete surface adsorption and coating under mild conditions, avoiding premature reactions or agglomeration between components. A gradient heat treatment is used on the wet intermediate, first heating and then cooling. The 85℃ isothermal stage promotes the solidification and stabilization of the activator within the carrier, while the cooling to 50℃ stage helps alleviate internal stress, preventing damage to the carrier structure due to rapid drying and maintaining the integrity of the channels. The three-step preparation process described above—vacuum pretreatment, segmented pressure impregnation, and programmed temperature heat treatment—achieved high loading, uniform distribution, and stable curing of the activator in the zeolite carrier. This improved the storage stability of the activator and ensured the controllable release of the activating components during use.

[0030] 5. Meets the core needs of the building materials industry in processing bulk materials: In the field of resource utilization of bulk solid wastes such as steel slag and fly ash, compared with the activator carrier produced by mesoporous molecular sieves and complex processes, the present invention has a moderate cost, and the natural clinoptilolite carrier route meets the core needs of the building materials industry in processing bulk materials at low cost. Detailed Implementation

[0031] The detailed material proportions in the technical solution of this invention will be described below. It should be understood that the provided embodiments do not represent all possible embodiments of this invention, but only a part of them. Based on these embodiments, those skilled in the art can deduce all other embodiments covered by this invention without creative work. These derived embodiments also fall within the protection scope of this invention.

[0032] A supported composite activator based on a crystalline porous zeolite carrier comprises the following raw materials in parts by weight: 55-58 parts of crystalline modified zeolite, 12-14 parts of nucleation promoter, 9-11 parts of functional enhancer, 8-9 parts of sodium hydroxide, and 35-37 parts of sodium silicate.

[0033] Furthermore, the preparation method of crystalline modified zeolite is as follows: natural clinoptilolite ore is crushed and ground to a fineness of 200 mesh or higher, then reacted with an inorganic acid (1-2 mol / L hydrochloric acid or nitric acid) at 80-90℃ with stirring for 3-4 hours. After washing off the acid and drying, the zeolite is calcined in a muffle furnace with programmed temperature rise to obtain crystalline modified zeolite. The silica-alumina ratio of the crystalline modified zeolite is 4-6, and the specific surface area is ≥380 m². 2 / g.

[0034] Furthermore, the temperature is increased to between 450°C and 550°C and held for 2-4 hours; this temperature range is sufficient to remove impurity molecules, but also avoids the collapse of the zeolite crystal structure due to overheating.

[0035] Furthermore, the nucleation promoter is composed of sodium aluminate and lithium silicate, with the preferred mass ratio of sodium aluminate to lithium silicate being 4:3.

[0036] Furthermore, the functional enhancer is composed of n-octyltriethoxysilane, sodium bentonite, and ultrafine slag powder, with the preferred mass ratio of n-octyltriethoxysilane, sodium bentonite, and ultrafine slag powder being 3:4:4.

[0037] Furthermore, sodium aluminate is an industrial-grade solid powder with a purity of ≥95%.

[0038] Furthermore, lithium silicate is an industrial-grade solid powder, whose main component is lithium silicate with a purity of ≥90%.

[0039] Furthermore, n-octyltriethoxysilane is an industrial-grade colorless and transparent liquid with a liquid main component content of ≥97%.

[0040] Furthermore, sodium-based bentonite is a solid powder with a montmorillonite content ≥85% and an expansion capacity ≥15 mL / g.

[0041] Furthermore, the ultrafine slag powder is a powder made by grinding granulated blast furnace slag, with a specific surface area of ​​not less than 550 m². 2 / kg, preferably 600 m 2 / kg or more.

[0042] Furthermore, sodium hydroxide is a solid powder with a solid content greater than 96%.

[0043] Furthermore, sodium silicate is a solid powder with a modulus (SiO2 / Na2O molar ratio) of 2.3.

[0044] The preparation method of the supported composite activator based on crystalline porous zeolite support includes the following steps: a. Add equal masses of water to sodium hydroxide and sodium silicate respectively and stir until homogeneous to prepare sodium hydroxide solution and sodium silicate solution. After the solution temperature stabilizes, mix the two solutions to obtain a basic activator solution with a modulus of 1.4-1.5; b. Pretreatment of the crystalline modified zeolite under vacuum conditions, the specific steps of which are as follows: After weighing the prepared crystalline modified zeolite, spread it evenly in a high-temperature resistant ceramic crucible or evaporating dish, and place it in a vacuum drying oven; start the vacuum pump, evacuate the pressure inside the oven to -0.1 MPa, set the temperature to 110℃, and maintain this condition for 2-3 hours; after the heat treatment is completed, turn off the heating and allow the material to cool naturally to room temperature while maintaining the vacuum condition; the pretreatment is complete, and the pretreated crystalline modified zeolite carrier is obtained, which should be used for the next impregnation step as soon as possible to prevent re-absorption of moisture; The activation solution containing nucleation promoters and function enhancers is injected sequentially, followed by segmented pressure-maintaining impregnation. The segmented pressure-maintaining impregnation is divided into a low-pressure permeation stage and a normal-pressure adsorption and equilibrium stage, and the specific operation steps are as follows: Low-pressure permeation stage: The pretreated crystalline modified zeolite is placed into the impregnation tank, the tank is closed, and a vacuum is drawn to -0.1 MPa and maintained for 15 minutes. While maintaining this vacuum, the first impregnation solution, which is a mixture of nucleation promoter (sodium aluminate + lithium silicate) and 1 / 3 of the basic activator solution, is slowly injected. After the injection is completed, the vacuum valve is closed, and nitrogen gas is introduced into the tank to a pressure of 0.5 MPa. The tank is then impregnated at room temperature (25±5℃) for 4 hours while intermittently stirring at a low speed (30 rpm) (on for 5 minutes, off for 25 minutes). The low-speed intermittent stirring can promote the permeation of the impregnation solution into the zeolite channels and avoid damage to the carrier or entrainment of air bubbles caused by vigorous stirring. Atmospheric pressure adsorption and equilibrium stage: Slowly release the pressure inside the tank to atmospheric pressure, open the feed port, add the functional enhancer (n-octyltriethoxysilane + sodium bentonite + ultrafine slag powder) and the remaining basic activator solution, close the feed port, and stir continuously at 60 rpm for 2 hours under atmospheric pressure and 40℃ conditions to ensure that the components are fully mixed and complete the final adsorption. Finally, the temperature was raised to 60°C and stirred at normal pressure for 1 hour to promote the initial interaction between the components. After impregnation, the slurry in the tank was discharged to obtain a wet intermediate. c. The supported composite activator is obtained after heat treatment. The specific operation steps are as follows: The wet intermediate was evenly spread in a drying tray, with a thickness not exceeding 2 cm. The tray was placed in a drying oven and subjected to programmed temperature rise heat treatment in an air atmosphere. First, the temperature was increased from room temperature to 85°C at a rate of 2°C / min and held at 85±5°C for 8 hours. Then, the temperature was decreased to 50°C at a rate of 1°C / min and held for 2 hours to balance the internal stress and moisture distribution of the material. After the heat treatment, the heating power was turned off, the ventilation vents of the drying oven were opened, and the material was allowed to cool naturally to room temperature inside the oven. Finally, the dried block material was taken out, lightly crushed with a mortar and pestle or a small crusher, and passed through an 80-mesh (approximately 180μm) standard sieve to obtain a dry, uniform powdered supported composite activator, which was then sealed and packaged for later use.

[0045] A method for preparing a steel slag powder-fly ash cementitious material includes the following steps: a. Precursor preparation: Fly ash and steel slag powder are mixed at a mass ratio of 6:4~6.5:3.5 and ground together until the specific surface area is ≥500 m². 2 / kg, to obtain the precursor; steel slag powder with a mesh size ≥325 mesh, specific surface area ≥400 m² / kg, and main chemical components of CaO 35-50%, SiO2 10-20%, Fe2O3 15-25%, Al2O3 5-10%; fly ash is Grade I fly ash with a specific surface area not less than 350 m² / kg, loss on ignition not greater than 5%, and main chemical components of SiO2 40-60%, Al2O3 20-30%, CaO ≤10%; b. Use of activator: Dissolve the supported composite activator in water and stir evenly, with the amount of water added so that the water-to-solid ratio is 0.3 (total water content / solid content of all solid powders including fly ash, steel slag powder and supported composite activator). c. Segmented mixing process: The first stage of mixing is a high-concentration premix. All the loaded composite activator solution and 1 / 3 of the total mass of the precursor are added to the mixing vessel and stirred at low speed (140±5 rpm) for 2 minutes to initially wet the powder and prevent powder from flying and slurry from splashing out. Then, the stirring speed is increased to high speed (285±10 rpm) for 3 minutes to break up agglomerates and promote full contact between the activator and the precursor to form a uniform and somewhat fluid thick slurry. The activator concentration in the mixture is extremely high in this stage, and the reaction starts rapidly. The second stage of mixing is the final dilution mixing. Without stopping the machine, the remaining 2 / 3 of the precursor is continuously added to the mixing tank. After all the precursor is added, the mixture is first stirred at a low speed (140±5 rpm) for 1 minute to ensure that the newly added dry powder is coated with the slurry and to prevent dust from being generated. Finally, the mixture is stirred at a high speed (285±10 rpm) for 2 minutes to ensure that the system reacts evenly and fully until a gelling material slurry with uniform color and consistent texture is obtained. d. Molding and curing to obtain steel slag powder-fly ash cementitious material.

[0046] Example 1.

[0047] The preparation method of crystalline modified zeolite is as follows: natural clinoptilolite ore is crushed and ground to a fineness of 200 mesh or higher, then reacted with an inorganic acid (1.5 mol / L hydrochloric acid) under heating (85℃) with stirring for 4 hours. The zeolite, after being acid-washed and dried, is then calcined in a muffle furnace at a programmed temperature (500℃, held for 3 hours) to obtain crystalline modified zeolite. The silica-alumina ratio of the crystalline modified zeolite is 4-6, and the specific surface area is ≥380 m². 2 / g.

[0048] The preparation method of the supported composite activator based on crystalline porous zeolite support includes the following steps: a. Add equal amounts of water to sodium hydroxide (9 parts) and sodium silicate (35 parts) and stir until homogeneous to prepare sodium hydroxide solution and sodium silicate solution. After the solution temperature is constant, mix the two solutions to obtain a basic activator solution with a modulus of 1.4. b. Pretreatment of the crystalline modified zeolite under vacuum conditions, the specific steps of which are as follows: After weighing the prepared crystalline modified zeolite, spread it evenly in a high-temperature resistant ceramic crucible or evaporating dish, and place it in a vacuum drying oven. Start the vacuum pump and evacuate the pressure inside the oven to -0.1 MPa. Set the temperature to 110℃ and maintain this condition for 2-3 hours. After the heat treatment is completed, turn off the heating and allow the material to cool naturally to room temperature while maintaining the vacuum. The pretreatment is complete, and the pretreated crystalline modified zeolite carrier is obtained. The activation solution containing nucleation promoters and function enhancers is injected sequentially, followed by segmented pressure impregnation. The segmented pressure impregnation is divided into a low-pressure permeation stage and a normal-pressure adsorption and equilibrium stage, and the specific operation steps are as follows: Low-pressure permeation stage: Take 58 parts of the pretreated crystalline modified zeolite and put it into the impregnation tank. Close the tank and evacuate to -0.1 MPa, maintaining the vacuum for 15 minutes. While maintaining this vacuum, slowly inject the first impregnation solution, which is a mixture of 14 parts of nucleation promoter (8 parts of sodium aluminate + 6 parts of lithium silicate) and 1 / 3 of the basic activator solution. After the injection is completed, close the vacuum valve and fill the tank with nitrogen to a pressure of 0.5 MPa. Impregnate at room temperature (25±5℃) for 4 hours while intermittently stirring at low speed (30 rpm) (on for 5 minutes, off for 25 minutes). Atmospheric pressure adsorption and equilibrium stage: Slowly release the pressure inside the tank to atmospheric pressure, open the feed port, and add 11 parts of functional enhancer (3 parts of n-octyltriethoxysilane, 4 parts of sodium bentonite, and 4 parts of ultrafine slag powder) and the remaining basic activator solution. Close the feed port and stir continuously at 60 rpm for 2 hours under atmospheric pressure and 40°C to ensure thorough mixing of all components and completion of final adsorption. Finally, the temperature was raised to 60°C, and stirring was continued at atmospheric pressure for 1 hour to promote the initial interaction between the components. After impregnation, the slurry in the tank was drained to obtain a wet intermediate. c. The supported composite activator is obtained after heat treatment. The specific operation steps are as follows: The wet intermediate was evenly spread in a drying tray, with a thickness not exceeding 2 cm. The tray was placed in a drying oven and subjected to programmed temperature rise heat treatment in an air atmosphere. First, the temperature was increased from room temperature to 85°C at a rate of 2°C / min and held at 85±5°C for 8 hours. Then, the temperature was lowered to 50°C and held for 2 hours to balance the internal stress and moisture distribution of the material. After heat treatment, the heating power was turned off, and the vents of the drying oven were opened to allow the material to cool naturally to room temperature inside the oven. Finally, the dried block material was removed, lightly crushed using a mortar and pestle or a small crusher, and passed through an 80-mesh (approximately 180μm) standard sieve to obtain a dry, uniform powdered supported composite activator final product, which was then sealed and packaged for later use.

[0049] A method for preparing steel slag powder-fly ash cementitious material includes the following steps: a. Precursor preparation: Fly ash and steel slag powder are mixed at a mass ratio of 6:4, that is, 120 parts of fly ash and 80 parts of steel slag powder are mixed and ground together until the specific surface area is 520 m² / kg to obtain the precursor; b. Use of activator: Dissolve the supported composite activator in water and stir evenly, with the amount of water added so that the water-to-solid ratio is 0.3 (total water content / solid content of all solid powders including fly ash, steel slag powder and supported composite activator). c. Segmented mixing process: The first stage of mixing is a high-concentration premix. All the supported composite activator solution and 1 / 3 of the total mass of the precursor are added to the mixing vessel and stirred at low speed (140±5 rpm) for 2 minutes to initially wet the powder. Then, the stirring speed is increased to high speed (285±10 rpm) for 3 minutes to form a uniform and somewhat fluid thick slurry. The activator concentration in the mixture is extremely high in this stage, and the reaction starts rapidly. The second stage of mixing is the final dilution mixing. While maintaining the mixing speed as described above, continuously add the remaining 2 / 3 of the precursor to the mixing tank. After all the precursor has been added, first stir at a low speed (140±5 rpm) for 1 minute to ensure the dry powder is fully coated. Finally, switch to high speed (285±10 rpm) and stir for 2 minutes until a uniformly colored and consistent gelling material slurry is obtained. d. Molding and curing to obtain steel slag powder-fly ash cementitious material.

[0050] Example 2.

[0051] The preparation methods of the crystalline modified zeolite, the supported composite activator, and the steel slag powder-fly ash cementitious material in this embodiment are the same as those in Example 1, but the proportions of each component in the supported composite activator are changed, and the specific parameters are as follows.

[0052] Supported composite activator: 58 parts of crystalline modified zeolite, 12 parts of nucleation promoter (7 parts of sodium aluminate and 5 parts of lithium silicate), 9 parts of functional enhancer (3 parts of n-octyltriethoxysilane, 3 parts of sodium bentonite and 3 parts of ultrafine slag powder), 9 parts of sodium hydroxide, and 35 parts of sodium silicate with a modulus of 2.3. Example 3.

[0053] The preparation methods of the crystalline modified zeolite, the supported composite activator, and the steel slag powder-fly ash cementitious material in this embodiment are the same as those in Example 1, but the proportions of each component in the supported composite activator are changed, and the specific parameters are as follows.

[0054] Supported composite activator: 55 parts of crystalline modified zeolite, 14 parts of nucleation promoter (8 parts of sodium aluminate and 6 parts of lithium silicate), 11 parts of functional enhancer (3 parts of n-octyltriethoxysilane, 4 parts of sodium bentonite and 4 parts of ultrafine slag powder), 8 parts of sodium hydroxide, and 37 parts of sodium silicate with a modulus of 2.3. Comparative Example 1 (conventional activator).

[0055] The preparation method of the steel slag powder-fly ash cementitious material in this comparative example is the same as that in Example 1, except that the traditional composite activator is replaced by the supported composite activator of the present invention, and the relevant parameters are as follows: Traditional composite activator: 9 parts sodium hydroxide and 35 parts sodium silicate with a modulus of 2.3.

[0056] Comparative Example 2 (attapulgite replacing crystalline modified zeolite) The preparation methods of the composite activator and steel slag powder-fly ash cementitious material in this comparative example are the same as those in Example 1, except that attapulgite replaces crystalline modified zeolite, and the relevant parameters are as follows: Composite activator: 58 parts attapulgite, 14 parts nucleation promoter (8 parts sodium aluminate and 6 parts lithium silicate), 11 parts functional enhancer (3 parts n-octyltriethoxysilane, 4 parts sodium bentonite and 4 parts ultrafine slag powder), 9 parts sodium hydroxide, and 35 parts sodium silicate with a modulus of 2.3.

[0057] Comparative Example 3 (unmodified zeolite).

[0058] The preparation methods of the composite activator and steel slag powder-fly ash cementitious material in this comparative example are the same as in Example 1, except that unmodified zeolite replaces crystalline modified zeolite. Specifically, the natural clinoptilolite ore is crushed and ground to a fineness of 200 mesh or higher, without acid washing or calcination. The relevant parameters are shown below: Composite activator: 58 parts unmodified zeolite, 14 parts nucleation promoter (8 parts sodium aluminate and 6 parts lithium silicate), 11 parts functional enhancer (3 parts n-octyltriethoxysilane, 4 parts sodium bentonite and 4 parts ultrafine slag powder), 9 parts sodium hydroxide, and 35 parts sodium silicate with a modulus of 2.3.

[0059] Comparative Example 4 (without functional enhancer).

[0060] The preparation methods of the composite activator and steel slag powder-fly ash cementitious material in this comparative example are the same as those in Example 1, except that the composite activator does not contain a functional enhancer, and the relevant parameters are as follows: Composite activator: 58 parts of crystalline modified zeolite, 14 parts of nucleation promoter (8 parts of sodium aluminate and 6 parts of lithium silicate), 9 parts of sodium hydroxide, and 35 parts of sodium silicate with a modulus of 2.3; Comparative Example 5 (without nucleation promoter).

[0061] The preparation methods of the composite activator and steel slag powder-fly ash cementitious material in this comparative example are the same as those in Example 1, except that the composite activator does not contain a nucleation promoter, and the relevant parameters are as follows: Composite activator: 58 parts of crystalline modified zeolite, 11 parts of functional enhancer (3 parts of n-octyltriethoxysilane, 4 parts of sodium bentonite and 4 parts of ultrafine slag powder), 9 parts of sodium hydroxide, and 35 parts of sodium silicate with a modulus of 2.3. Table 1 shows the test results of the strength, toughness, and durability performance indicators of the examples and comparative examples.

[0062] Table 1 shows the performance test results of the examples and comparative examples.

[0063] All specimens prepared for the tests were neat cement paste specimens. The standards and methods referenced for each test are as follows: Compressive and flexural strength tests: Refer to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T 17671-2021). Specimens were cured for 28 days under standard curing conditions of (20±1)℃ and relative humidity above 90%; the flexural-compression ratio is the ratio of flexural strength to compressive strength.

[0064] Impact resistance test: The impact resistance was tested according to the "Test Method for Performance of Glass Fiber Reinforced Cement" (GB / T 15231-2008); the specimen size was 120 mm × 50 mm × 10 mm. The specimens were cured for 26 days at 20±3℃ and relative humidity above 80%, and then placed in a well-ventilated room for 48 hours before the test.

[0065] Fracture energy test: Referring to the three-point bending test in the "Specification for Fracture Test of Hydraulic Concrete" (DL / T 5332-2005), the span-to-height ratio of the specimen was 2.5, the joint-to-height ratio of the precast open specimen was 0.3, and the specimen size was 160 mm × 40 mm × 40 mm. Curing was carried out for 28 days under standard curing conditions of (20±1)℃ and relative humidity above 90%.

[0066] Unsteady-state chloride ion migration coefficient: determined according to the rapid chloride ion migration coefficient method (RCM method) in the "Standard for Test Methods of Long-term Performance and Durability of Concrete" (GB / T50082-2024). The lower the unsteady-state chloride ion migration coefficient, the stronger the material's resistance to chloride ion penetration.

[0067] The performance indicators of the embodiments and comparative examples are analyzed below.

[0068] 1. Comparative analysis of strength indicators (flexural and compressive strength): The embodiments of the present invention exhibit significant advantages in both 28-day compressive strength and flexural strength, demonstrating the synergistic enhancement effect of the "carrier-nucleation-toughening" system; Compared with traditional activators (Comparative Example 1): the compressive and flexural strengths of Example 1 were increased by 60% and 98%, respectively. Traditional strong alkali-activated reactions are violent and disordered, easily forming microscopic defects; while the present invention achieves controlled and sustained release of alkali components through crystalline modified zeolite, making the reaction stable and long-lasting, and the nucleation promoter (sodium aluminate / lithium silicate) further guides the formation of a dense, uniform, high-strength CASH gel network.

[0069] Compared with different carrier materials (Comparative Examples 2 and 3): Compared with attapulgite carrier (Comparative Example 2) and unmodified zeolite carrier (Comparative Example 3), the compressive strength of Example 1 is 31% and 20% higher, respectively. The layered irregular channels of attapulgite lead to uneven release, and the channels of unmodified zeolite are blocked; while crystalline modified zeolite, with its regular three-dimensional channels (0.4-0.7 nm) and high specific surface area (≥380 m²), is superior. 2 / g), ensuring efficient loading and precise release of the activator.

[0070] Compared with the absence of functional components (Comparative Examples 4 and 5): The absence of functional enhancer (Comparative Example 4) or nucleation promoter (Comparative Example 5) both lead to a decrease in strength. In particular, the absence of nucleation promoter results in disordered growth of hydration products and a decrease in the intrinsic strength of the gel network, demonstrating the key role of this component in strength.

[0071] 2. Comparative analysis of toughness indicators (impact energy and fracture energy): Example 1 shows that the impact energy is 65% higher than that of the traditional activator (Comparative Example 1). This is directly attributed to the multi-scale synergy of the functional enhancers: n-octyltriethoxysilane forms a strong hydrophobic film and physical adsorption layer on the surface of inorganic powder and hydration products through its long-chain alkyl group, which blocks water erosion and reduces the initiation of microcracks; sodium-based bentonite consumes energy at the micron scale through lamellar sliding and crack deflection; ultrafine slag powder optimizes the gradation at the macro scale to reduce stress concentration. The absence of any link (such as Comparative Example 4) leads to a significant reduction in impact energy.

[0072] The fracture energy of Example 1 was increased by 81% compared to Comparative Example 1. Higher fracture energy means that crack propagation requires more energy. This is not only due to the functional enhancer, but also to the denser and more uniform matrix formed by the nucleation promoter (comparative Example 5 showed a significant decrease in fracture energy), and the strong and tough bonding interface contributed by the stable reaction environment created by the zeolite carrier.

[0073] The flexural-compressive strength ratio (flexural strength / compressive strength ratio) of Example 1 is 17.4 × 10⁻⁶. -2 It is higher than all comparative examples (14.2-15.6×10). -2 ( ) is a comprehensive quantitative indicator that shows a significant improvement in the brittleness and a substantial increase in the toughness of a material.

[0074] 3. Comparative analysis of durability indicators (non-steady-state chloride ion migration coefficient) The chloride ion migration coefficient of Example 1 was 3.8 × 10⁻⁶. -12 m 2 The concentration of chloride ions ( / s) is at an extremely low level, reduced by 54% compared to traditional activators (Comparative Example 1), and by more than 35% compared to other comparative examples. The nucleation promoter guides the formation of a dense gel phase with lower porosity and smaller pore size. The ultrafine slag powder in the functional enhancer exerts a micro-aggregate filling effect, blocking capillary pores. A strong hydrophobic film and physical adsorption layer form on the surface of the n-octyltriethoxysilane hydration product, preventing water erosion. The slow-release effect of the zeolite carrier avoids the formation of loose products caused by excessively high local alkali concentrations, promoting a uniform and dense overall structure. This results in excellent resistance to chloride ion penetration.

[0075] This invention comprises a complementary and synergistic organic system consisting of a "crystalline modified zeolite carrier," a "nucleation promoter," and a "functional enhancer." The absence or substitution of any one of these components (as shown in the comparative examples) will lead to a weakness in the performance chain, particularly a significant decline in toughness and durability. This invention provides a scientifically sound and practical technical solution for the utilization of high-value-added resources such as steel slag and fly ash.

Claims

1. A supported composite activator based on a crystalline porous zeolite support, characterized in that, The raw materials include the following parts by weight: 55-58 parts of crystalline modified zeolite, 12-14 parts of nucleation promoter, 9-11 parts of functional enhancer, 8-9 parts of sodium hydroxide, and 35-37 parts of sodium silicate.

2. The supported composite activator according to claim 1, characterized in that, The preparation method of crystalline modified zeolite is as follows: crush and grind natural clinoptilolite ore to a mesh size of 200 or higher, then stir and react with inorganic acid under heating conditions for 3-4 hours. After washing off the acid and drying, the zeolite is calcined by programmed temperature increase to obtain crystalline modified zeolite.

3. The supported composite activator according to claim 2, characterized in that, The inorganic acid is 1-2 mol / L hydrochloric acid or nitric acid; the heating temperature is 80-90℃; the programmed temperature rise calcination is between 450℃ and 550℃, and the temperature is maintained for 2-4 hours.

4. The supported composite activator according to claim 1, characterized in that, The nucleation promoter is composed of sodium aluminate and lithium silicate.

5. The supported composite activator according to claim 1, characterized in that, The functional enhancer is composed of n-octyltriethoxysilane, sodium bentonite, and ultrafine slag powder.

6. A method for preparing a supported composite activator based on a crystalline porous zeolite support, characterized in that, Includes the following steps: a. Add equal masses of water to sodium hydroxide and sodium silicate respectively and stir until homogeneous to prepare sodium hydroxide solution and sodium silicate solution. After the solution temperature is constant, mix the two solutions to obtain a basic activator solution with a modulus of 1.4-1.

5. b. After pretreating the crystalline modified zeolite under vacuum conditions, it is injected in stages with an activation liquid containing nucleation promoters and functional enhancers, and impregnated under pressure in stages to obtain a wet intermediate. c. The wet intermediate is heat-treated to obtain a supported composite activator.

7. The method for preparing the supported composite activator according to claim 6, characterized in that, In step b, the crystalline modified zeolite is pretreated under vacuum conditions. The specific operation steps are as follows: After weighing the prepared crystalline modified zeolite, spread it evenly in a high-temperature resistant ceramic crucible or evaporating dish and place it in a vacuum drying oven; start the vacuum pump to evacuate the pressure inside the oven to -0.1 MPa, set the temperature to 110℃, and maintain this condition for 2-3 hours; after the heat treatment is completed, turn off the heating and allow the material to cool naturally to room temperature while maintaining the vacuum condition; the pretreatment is completed, and the pretreated crystalline modified zeolite carrier is obtained.

8. The method for preparing the supported composite activator according to claim 6, characterized in that, In step b, the segmented pressure-maintaining impregnation is divided into a low-pressure permeation stage and an atmospheric pressure adsorption and equilibrium stage, and the specific operation steps are as follows: Low-pressure permeation stage: The pretreated crystalline modified zeolite is put into the impregnation tank, the tank is closed, and a vacuum is drawn to -0.1 MPa and maintained for 15 minutes. While maintaining this vacuum, the nucleation promoter and 1 / 3 of the basic activator solution, i.e. the first impregnation solution, are slowly injected. After the injection is completed, the vacuum valve is closed, nitrogen is introduced into the tank to a pressure of 0.5 MPa, and the tank is impregnated at room temperature for 4 hours while intermittently stirring at 30 rpm. Atmospheric pressure adsorption and equilibrium stage: Slowly release the pressure inside the tank to atmospheric pressure, open the feed port, add the functional enhancer and the remaining basic activator solution, close the feed port, and stir continuously at 60 rpm for 2 hours under atmospheric pressure and 40℃ conditions to ensure that the components are fully mixed and complete the final adsorption. Finally, the temperature was raised to 60°C, and the mixture was stirred at normal pressure for 1 hour. After impregnation, the slurry in the tank was discharged to obtain a wet intermediate.

9. The method for preparing the supported composite activator according to claim 6, characterized in that, In step c, the specific operation steps of the heat treatment are as follows: Spread the wet intermediate evenly in a drying tray, with a thickness not exceeding 2cm; place the tray in a drying oven and perform programmed temperature rise heat treatment in an air atmosphere; first, raise the temperature from room temperature to 85℃ at a rate of 2℃ / min, and maintain the temperature at 85±5℃ for 8 hours; then, lower the temperature to 50℃ at a rate of 1℃ / min and maintain it for 2 hours; after the heat treatment is completed, turn off the heating power, open the ventilation vents of the drying oven, and allow the material to cool naturally to room temperature inside the oven; finally, take out the dried block material, lightly crush it with a mortar and pestle or a small crusher, pass it through an 80-mesh standard sieve, and obtain a dry, uniform powdered loaded composite activator, which is then sealed and packaged for later use.

10. A method for preparing a steel slag powder-fly ash cementitious material, characterized in that, Includes the following steps: a. Precursor preparation: Fly ash and steel slag powder are mixed at a mass ratio of 6:4~6.5:3.5 and ground together until the specific surface area is ≥500 m². 2 / kg, to obtain the precursor; b. Use of activator: Dissolve the supported composite activator in water and stir until homogeneous, with the amount of water added so that the water-to-solid ratio is 0.3; c. Segmented mixing process: The first stage of mixing is a high-concentration premix. All the loaded composite activator solution and 1 / 3 of the total mass of the precursor are added to the mixing tank and stirred at 140±5 rpm for 2 minutes, then stirred at 285±10 rpm for 3 minutes to form a uniform and fluid thick slurry. The second stage of mixing is the final dilution mixing. Without stopping the machine, the remaining 2 / 3 of the precursor is continuously added to the mixing pot. After all the precursor is added, the mixture is first stirred at 140±5 rpm for 1 minute, and then stirred at 285±10 rpm for 2 minutes until a gelling material slurry with uniform color and consistent texture is obtained. d. Molding and curing to obtain steel slag powder-fly ash cementitious material.

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