High-durability and high-toughness slag powder-steel slag powder quaternary synergistic excitation-reinforcing agent and preparation method of gel system mortar

Abstract

The invention belongs to the technical field of building material and solid waste resource utilization, and relates to a high-durability and high-toughness slag powder-steel slag powder quaternary synergistic excitation-reinforcing agent and a preparation method of gel system mortar. The quaternary synergistic excitation-reinforcing agent comprises the following raw materials in parts by mass: 4-16 parts of sodium hydroxide, 79 parts of sodium silicate, 4-16 parts of aluminum sulfate and 60 parts of metakaolin, and the sum of the mass parts of the sodium hydroxide and the aluminum sulfate is 20. According to the quaternary synergistic excitation-reinforcing agent, sodium hydroxide and sodium silicate are used as main excitants, and aluminum sulfate serving as a function regulator and metakaolin serving as a high-activity aluminum-silicon source and a micro aggregate are introduced to serve as synergistic reinforcing components; the four components cooperate to jointly form an excitation-reinforcement composite system with high durability and high toughness; the sulfate erosion resistance, the chloride ion penetration resistance, the carbonization resistance, the toughness and the impact resistance of the slag powder-steel slag powder cementing system mortar are 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 mortar with a high-durability and high-toughness slag powder-steel slag powder quaternary synergistic activator-reinforcer and cementing system. Background Technology

[0002] Slag and steel slag are major solid wastes generated by the iron and steel industry, and their resource utilization is crucial for environmental protection and sustainable development. Preparing alkali-activated cementitious materials through mechanical activation and chemical activation is an effective way to dispose of these solid wastes. Traditional sodium hydroxide-sodium silicate binary activator systems, while showing significant activation effects, generally suffer from problems such as excessively rapid setting, large early shrinkage, high brittleness, and insufficient durability (e.g., resistance to sulfate attack and carbonization).

[0003] In existing technologies, sodium carbonate and silica fume are used to improve performance. Sodium carbonate delays setting through pH buffering and competitive reactions, but this may lead to slow early strength development and has limited contribution to improving the material's toughness and dynamic properties. While the addition of silica fume can improve early strength and density, it accelerates setting time and has no significant effect on improving the material's brittleness; the material is still prone to pulverization under impact loads.

[0004] Therefore, developing an activation-reinforcement toughening agent that can synergistically improve mechanical properties and durability, and fundamentally improve material brittleness and endow it with excellent impact resistance is key to promoting the application of alkali-activated cementitious materials (industrial solid waste materials) in advanced applications such as protective engineering and earthquake-resistant structures. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing a high-durability, high-toughness quaternary synergistic activator-reinforcer and slag powder-steel slag powder cementitious system mortar. This cementitious system uses sodium hydroxide and sodium silicate as the main activators, and innovatively introduces aluminum sulfate as a functional regulator and metakaolin as a highly active aluminum-silicon source and micro-aggregate as synergistic reinforcing components; the four components work synergistically to form an activator-reinforcement composite system with high durability and high toughness.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A high-durability and high-toughness slag powder-steel slag powder quaternary synergistic activator-reinforcer (hereinafter referred to as quaternary synergistic activator-reinforcer) comprises the following raw materials in parts by weight: 4-16 parts sodium hydroxide, 79 parts sodium silicate, 4-16 parts aluminum sulfate, and 60 parts metakaolin, wherein the sum of the parts by weight of sodium hydroxide and aluminum sulfate is 20 parts; all four materials are dry powders.

[0008] Furthermore, the sodium hydroxide is a solid particle, and its composition contains no less than 96% sodium hydroxide.

[0009] Furthermore, the sodium silicate is an instant sodium silicate powder with a modulus of 2.0-2.5 and a sieve pass rate of not less than 98% through a 100-mesh sieve.

[0010] Furthermore, the aluminum sulfate is anhydrous aluminum sulfate powder, and its Al2(SO4)3 content is not less than 99%.

[0011] Furthermore, the metakaolin is a highly reactive metakaolin, with a total SiO2 and Al2O3 content of not less than 95%, a loss on ignition of not more than 3%, and a specific surface area of ​​not less than 15 m². 2 / g.

[0012] A method for preparing a quaternary synergistic exciter-enhancer involves weighing sodium hydroxide, sodium silicate, aluminum sulfate, and metakaolin in the required proportions, mixing the raw materials evenly, and sealing and storing them to prevent moisture.

[0013] A method for preparing slag powder-steel slag powder cementitious mortar using a quaternary synergistic activator-reinforcer specifically includes the following steps: Step 1: Weigh out slag powder, steel slag powder, and quartz sand and pour them into a planetary mixer in sequence. Mix at low speed (500 r / min) for 1 minute to obtain a uniformly dispersed dry mixture. Step 2: Pour the quaternary synergistic activator-enhancer into the mixer and continue to mix it with the dry mixture from Step 1 at low speed for 1 minute to ensure uniform mixing. Step 3: Pour water into the mixer, adjust the speed to medium-high speed (800-1000r / min), and stir for 2 minutes to obtain the quaternary synergistic activation-reinforced slag powder-steel slag powder cementitious system mortar.

[0014] Furthermore, the slag powder is granulated blast furnace slag powder, and its standard should comply with the slag powder S105 standard required by GB / T18046-2017 "Granulated blast furnace slag powder for use in cement, mortar and concrete".

[0015] Furthermore, the Fe2O3 content in the steel slag powder should be no less than 25%, its fineness should be no less than 300 mesh, and its moisture content should be no more than 1%.

[0016] Furthermore, the mass ratio of slag powder, steel slag powder, quartz sand, and water is 7:3:14:4.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows.

[0018] 1. Synergistic construction of ultra-dense microstructure: The coupling reaction of aluminum sulfate and metakaolinite generates a large amount of CASH gel and ettringite; these two products fill and interweave with each other to form a microstructure with extremely low porosity and small pore size (<20nm); this structure is the physical basis for high durability and can effectively prevent the intrusion of external corrosive media.

[0019] 2. Excellent resistance to sulfate attack: Traditional cementitious materials are easily damaged by sulfate attack, generating expansive products. The system of this invention, due to its inherent high density, makes it difficult for external sulfate ions to penetrate. Simultaneously, the system has introduced sufficient SO4 through aluminum sulfate. 2- It exists stably in ettringite, achieving "internal equilibrium," which reduces the driving force and space for destructive reactions with subsequently invading sulfates.

[0020] 3. Excellent resistance to chloride ion penetration: The dense microstructure and high aluminum content of CASH gel have significant physical adsorption and chemical curing effects on chloride ions, which can effectively reduce the diffusion rate of chloride ions, protect the internal steel bars, and greatly extend the service life of the structure in marine and de-icing salt environments.

[0021] 4. High resistance to carbonization: Compared with traditional high calcium-silicon ratio CSH gel, low calcium-silicon ratio CSH gel has a lower alkali reserve requirement and is more stable. In addition, its dense structure hinders the entry of CO2, which makes this system exhibit excellent resistance to carbonization.

[0022] 5. High toughness and impact resistance: The fiber bridging effect of ettringite crystals and the crack deflection effect of metakaolin layers work together to give the material excellent toughness. Dynamic impact tests show that its toughness index far exceeds that of traditional systems, and the failure mode changes from brittle crushing to maintaining integrity. Attached Figure Description

[0023] Figure 1 Example and comparative example: 28-day compressive strength bar chart.

[0024] Figure 2 Example and comparative bar chart of compressive strength and corrosion resistance coefficient.

[0025] Figure 3 Bar chart of unsteady-state chloride ion migration coefficients for examples and comparative examples.

[0026] Figure 4 Example and comparative examples: 28-day carbonization depth bar chart.

[0027] Figure 5 Example and comparative examples: 56-day drying shrinkage bar chart.

[0028] Figure 6Example and comparative dynamic toughness index bar chart.

[0029] Figure 7 Example and comparative dynamic compressive strength bar chart. Detailed Implementation

[0030] The technical solutions of this invention will be described in detail 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.

[0031] A high-durability and high-toughness slag powder-steel slag powder quaternary synergistic activator-reinforcer (hereinafter referred to as quaternary synergistic activator-reinforcer) comprises the following raw materials in parts by weight: 4-16 parts sodium hydroxide, 79 parts sodium silicate, 4-16 parts aluminum sulfate, and 60 parts metakaolin, wherein the sum of the parts by weight of sodium hydroxide and aluminum sulfate is 20 parts; all four materials are dry powders.

[0032] Furthermore, the sodium hydroxide is a solid particle, and its composition contains no less than 96% sodium hydroxide.

[0033] Furthermore, the sodium silicate is an instant sodium silicate powder with a modulus of 2.0-2.5 and a sieve pass rate of not less than 98% through a 100-mesh sieve.

[0034] Furthermore, the aluminum sulfate is anhydrous aluminum sulfate powder, and its Al2(SO4)3 content is not less than 99%.

[0035] Furthermore, the metakaolin is a highly reactive metakaolin, with a total SiO2 and Al2O3 content of not less than 95%, a loss on ignition of not more than 3%, and a specific surface area of ​​not less than 15 m². 2 / g.

[0036] A method for preparing a quaternary synergistic exciter-enhancer involves weighing sodium hydroxide, sodium silicate, aluminum sulfate, and metakaolin in the required proportions, mixing the raw materials evenly, and sealing and storing them to prevent moisture.

[0037] A method for preparing slag powder-steel slag powder cementitious mortar using a quaternary synergistic activator-reinforcer specifically includes the following steps: Step 1: Weigh out slag powder, steel slag powder, and quartz sand and pour them into a planetary mixer in sequence. Mix at low speed (500 r / min) for 1 minute to obtain a uniformly dispersed dry mixture. The mass ratio of slag powder, steel slag powder, quartz sand, and water is 7:3:14:4. Step 2: Pour the quaternary synergistic activator-enhancer into the mixer and continue to mix it with the dry mixture from Step 1 at low speed for 1 minute to ensure uniform mixing. Step 3: Pour water into the mixer, adjust the speed to medium-high speed (800-1000r / min), and stir for 2 minutes to obtain the quaternary synergistic activation-reinforced slag powder-steel slag powder cementitious system mortar.

[0038] The Fe2O3 content of the above-mentioned steel slag powder should be no less than 25%, its fineness should be no less than 300 mesh, and its moisture content should be no more than 1%. The above-mentioned slag powder is granulated blast furnace slag powder, and its standard should meet the requirements of GB / T18046-2017 "Granulated Blast Furnace Slag Powder for Cement, Mortar and Concrete" as slag powder S105 standard.

[0039] In all the proportions of the following examples and comparative examples, the slag powder + steel slag powder is 1000 parts, the quartz sand is 1400 parts, and the water is 400 parts.

[0040] Example 1. NaOH + Na2SiO3 + Al2(SO4)3 + metakaolin (low aluminum sulfate ratio).

[0041] Quaternary synergistic activator-enhancer (parts by weight): Sodium hydroxide 16 parts, sodium silicate 79 parts, aluminum sulfate 4 parts, metakaolin 60 parts; Cementitious materials: 700 parts slag powder, 300 parts steel slag powder; Aggregate: 1400 parts of quartz sand; Water: 400 servings.

[0042] A method for preparing a high-durability, high-toughness quaternary synergistic activation-reinforcement slag powder-steel slag powder cementitious system mortar, specifically including the following steps: Step 1: Preparation of quaternary synergistic activator-enhancer: Weigh out sodium hydroxide, sodium silicate, aluminum sulfate and metakaolin according to the above mass proportions, mix all the activator dry powder evenly and seal and store in a moisture-proof container; Step 2: Weigh out the slag powder, steel slag powder, and standard sand and pour them into the planetary mixer in sequence. Mix at a speed of 500 r / min for 1 minute to obtain a uniformly dispersed dry mixture. Step 3: Pour the quaternary synergistic activator-enhancer prepared in Step 1 into a mixer and continue to mix it with the dry mixture from Step 2 at low speed for 1 minute to ensure uniform mixing. Step 4: Pour the weighed water into the mixer, adjust the speed to 900 r / min, and stir for 2 minutes to obtain the quaternary synergistic activation-reinforced slag powder-steel slag powder cementitious system mortar.

[0043] Example 2. NaOH + Na2SiO3 + Al2(SO4)3 + metakaolin (with a medium aluminum sulfate ratio).

[0044] Quaternary synergistic activator-enhancer (parts by weight): sodium silicate 79 parts, sodium hydroxide 10 parts, aluminum sulfate 10 parts, metakaolin 60 parts; Cementitious materials: 700 parts slag powder, 300 parts steel slag powder; Aggregate: 1400 parts of quartz sand; Water: 400 portions; The preparation method of the quaternary synergistic activation-enhanced slag powder-steel slag powder cementitious system mortar is the same as that in Example 1.

[0045] Example 3. NaOH + Na2SiO3 + Al2(SO4)3 + metakaolin (high aluminum sulfate ratio).

[0046] Quaternary synergistic activator-enhancer (parts by weight): sodium silicate 79 parts, sodium hydroxide 4 parts, aluminum sulfate 16 parts, metakaolin 60 parts; Cementitious materials: 700 parts slag powder, 300 parts steel slag powder; Aggregate: 1400 parts of quartz sand; Water: 400 portions; The preparation method of the quaternary synergistic activation-enhanced slag powder-steel slag powder cementitious system mortar is the same as that in Example 1.

[0047] Comparative Example 1. Traditional NaOH + Na2SiO3 activator.

[0048] Activator (parts by weight): 79 parts sodium silicate, 20 parts sodium hydroxide; Cementitious materials: 700 parts slag powder, 300 parts steel slag powder; Aggregate: 1400 parts of quartz sand; Water: 400 servings.

[0049] The preparation method of the traditional (alkali) activated slag powder-steel slag powder cementitious system mortar is the same as that in Example 1.

[0050] Comparative Example 2. Traditional activator + silica fume.

[0051] Activator and silica fume (parts by weight): sodium silicate 79 parts, sodium hydroxide 20 parts, silica fume 60 parts; Cementitious materials: 700 parts slag powder, 300 parts steel slag powder; Aggregate: 1400 parts of quartz sand; Water: 400 servings.

[0052] The preparation method of silica fume and traditional (alkali) activated slag powder-steel slag powder mortar is the same as that in Example 1.

[0053] Comparative Example 3. Traditional activator + aluminum sulfate (without metakaolin).

[0054] Activator and aluminum sulfate (parts by mass): sodium silicate 79 parts, sodium hydroxide 10 parts, aluminum sulfate 10 parts; Cementitious materials: 700 parts slag powder, 300 parts steel slag powder; Aggregate: 1400 parts of quartz sand; Water: 400 servings.

[0055] The preparation method of aluminum sulfate and traditional (alkali) activated slag powder-steel slag powder mortar is the same as in Example 1.

[0056] Comparative Example 4. Traditional activator + metakaolin (without aluminum sulfate).

[0057] Activator and metakaolin (parts by mass): sodium silicate 79 parts, sodium hydroxide 20 parts, metakaolin 60 parts; Cementitious materials: 700 parts slag powder, 300 parts steel slag powder; Aggregate: 1400 parts of quartz sand; Water: 400 servings.

[0058] The preparation method of metakaolin and traditional (alkali) activated slag powder-steel slag powder mortar is the same as in Example 1.

[0059] Performance Tests and Results: Long-term durability tests were conducted on the cementitious mortar systems of the above embodiments and comparative examples, and the results are shown in Table 1.

[0060] Table 1. Results of long-term durability tests.

[0061] Compressive strength test: The specimens were cured for 28 days under the standard curing conditions of (20±2)℃ and relative humidity above 90%, in accordance with the "Standard for Test Methods of Basic Performance of Building Mortar" (JGJ / T 70-2009).

[0062] Resistance to sulfate attack: The compressive strength corrosion resistance coefficient was measured after 150 wet-dry cycles, in accordance with the "Standard for Test Methods of Long-Term Performance and Durability of Concrete" (GB / T 50082-2024).

[0063] 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.

[0064] Carbonation depth: Refer to the "Standard for Test Methods of Long-Term Performance and Durability of Concrete" (GB / T 50082-2024), which specifies the carbonation depth after 28 days of curing under specified conditions.

[0065] Drying shrinkage: Refer to the "Standard for Test Methods of Basic Performance of Building Mortar" (JGJ / T 70-2009) to measure the shrinkage value of the specimen after 56 days. Negative values ​​indicate shrinkage, and positive values ​​indicate expansion.

[0066] The impact (dynamic compression) performance test results of the cementitious mortars in the above embodiments and comparative examples are shown in Table 2.

[0067] Table 2 Dynamic compression performance indicators of split Hopkinson bar.

[0068] Dynamic compression tests were conducted on specimens using a split Hopkinson pressure bar (SHPB) device, based on the fundamental principles of one-dimensional stress wave theory. The specimens were cylinders with a diameter of Φ100 mm and a height of 50 mm, cured under standard conditions for 28 days. Stress waves were generated by a pneumatically driven bullet impacting the incident bar. Strain gauges attached to both the incident and transmitted bars were used to collect signals, and the dynamic stress-strain curves of the specimens were calculated using classical data processing methods. The measured index, dynamic toughness index, was defined as the area enclosed by the dynamic stress-strain curve, characterizing the material's energy absorption capacity under impact loading (unit: MPa·ε). The strain value was selected from the start of loading until the residual stress decreased to 80% of the peak stress; the dynamic compressive strength was the peak stress of the stress-strain curve.

[0069] Results Analysis and Conclusions: (1) Resistance to sulfate attack: The compressive strength and corrosion resistance coefficients of Examples 2 and 3 are both higher than 95%, which is far superior to Comparative Example 1 (81.5%). This shows that the system of the present invention has extremely high resistance to sulfate attack. Although Comparative Example 3 (aluminum sulfate alone) showed improvement, it only achieved the best effect when combined with metakaolin (Example), which proves the dual role of dense structure and internal sulfate balance.

[0070] (2) Resistance to chloride ion penetration: The unsteady chloride ion migration coefficient in Example 2 is as low as 2.45 × 10⁻⁶. -12 m 2 / s, reaching an extremely low permeability level, a reduction of approximately 72% compared to control 1. This directly demonstrates that the dense structure synergistically constructed from aluminum sulfate and metakaolin can extremely effectively block the migration of chloride ions.

[0071] (3) Anti-carbonization performance: The carbonization depth of all examples was significantly smaller than that of the comparative examples. The carbonization depth of Example 2 was only 0.8 mm, which was much smaller than the minimum value of 2.0 mm in the comparative examples (Comparative Example 4), showing excellent anti-carbonization ability. This is due to its low porosity and more stable low calcium-silicon ratio CASH gel phase.

[0072] (4) Volume stability: Referring to the "Specification for Mix Proportion Design of Masonry Mortar" (JGJ / T 98-2010), the shrinkage value of mortar should not exceed 0.15% (1500×10). -6 In accordance with the requirements of [specific criteria], the volume stability of all groups in this invention is significantly better than that of the benchmark. Particularly noteworthy is that Comparative Examples 1, 2, and 4 still exhibit a 56-day shrinkage (-550 to -710 × 10⁻⁶). -6 All embodiments of the present invention (containing aluminum sulfate and metakaolin) exhibit stable micro-expansion (+50 to +220 × 10⁻⁶). -6 This shift from "shrinkage" to "micro-expansion" means that the material has the ability to actively compensate for shrinkage and suppress cracking, providing a fundamental guarantee for improving the long-term durability of engineering structures.

[0073] (5) Toughness and Dynamic Performance: The split Hopkinson bar test confirmed that the dynamic toughness index of the embodiments of the present invention far exceeds that of the traditional system. Among them, the dynamic toughness index of Examples 1, 2 and 3 all reached above 3 MPa·ε, which is an improvement of 43.3%, 63.7% and 54.0% respectively compared with Comparative Example 1. The dynamic compressive strength all exceeded 75 MPa, which is an improvement of 13.6%, 21.3% and 14.6% respectively compared with Comparative Example 1. The brittleness of the material is significantly reduced and the dynamic performance is greatly improved.

[0074] This invention provides a quaternary synergistic activator-reinforcer based on aluminum sulfate and metakaolin. Through the excellent synergistic effect of these two components, a slag powder-steel slag powder mortar with ultra-high durability (resistance to sulfate attack, chloride ion penetration, carbonization, and micro-expansion properties), excellent volume stability, and high dynamic toughness has been successfully prepared. This material is particularly suitable for critical infrastructure, protective engineering, and various civil engineering structures with long-term durability requirements in harsh environments (marine environments, saline-alkali land, and sulfate-affected areas), providing an ideal material solution for achieving high-value utilization of solid waste resources and constructing long-life engineering projects.

Claims

1. A high-durability, high-toughness quaternary synergistic activator-reinforcer of slag powder and steel slag powder, characterized in that, The raw materials include the following parts by weight: 4-16 parts sodium hydroxide, 79 parts sodium silicate, 4-16 parts aluminum sulfate, and 60 parts metakaolin, with the sum of the parts by weight of sodium hydroxide and aluminum sulfate being 20 parts.

2. The high-durability, high-toughness slag powder-steel slag powder quaternary synergistic activator-reinforcer according to claim 1, characterized in that, The sodium hydroxide is a solid particle, and its composition contains not less than 96% sodium hydroxide.

3. The high-durability, high-toughness slag powder-steel slag powder quaternary synergistic activator-reinforcer according to claim 1, characterized in that, The sodium silicate is an instant sodium silicate powder with a modulus of 2.0-2.5 and a sieve pass rate of not less than 98% through a 100-mesh sieve.

4. The high-durability, high-toughness slag powder-steel slag powder quaternary synergistic activator-reinforcer according to claim 1, characterized in that, The aluminum sulfate is anhydrous aluminum sulfate powder, and its Al2(SO4)3 content is not less than 99%.

5. The high-durability, high-toughness slag powder-steel slag powder quaternary synergistic activator-reinforcer according to claim 1, characterized in that, The metakaolin is a highly reactive metakaolin, with a total SiO2 and Al2O3 content of not less than 95%, a loss on ignition of not more than 3%, and a specific surface area of ​​not less than 15 m². 2 / g.

6. The quaternary synergistic excitation-enhancing agent according to any one of claims 1-5, characterized in that, The preparation method is as follows: weigh sodium hydroxide, sodium silicate, aluminum sulfate and metakaolin according to the required ratio, mix the raw materials evenly and seal them for storage to prevent moisture.

7. A method for preparing slag powder-steel slag powder cementitious mortar using the quaternary synergistic activator-reinforcer according to any one of claims 1-5, characterized in that, Specifically, the steps include the following: Step 1: Weigh out slag powder, steel slag powder, and quartz sand and pour them into a planetary mixer in sequence. Mix at 500 r / min for 1 minute to obtain a uniformly dispersed dry mixture. Step 2: Pour the quaternary synergistic activator-enhancer into the mixer and continue to mix it with the dry mixture from Step 1 at low speed for 1 minute to ensure uniform mixing. Step 3: Pour water into the mixer, adjust the speed to 800-1000 r / min, and stir for 2 minutes to obtain the quaternary synergistic activation-reinforced slag powder-steel slag powder cementitious system mortar.

8. The method for making slag powder-steel slag powder cementitious system mortar according to claim 7, characterized in that, The slag powder is granulated blast furnace slag powder, and its standard should comply with the slag powder S105 standard required by GB / T18046-2017 "Granulated blast furnace slag powder for use in cement, mortar and concrete".

9. The method for making slag powder-steel slag powder cementitious system mortar according to claim 7, characterized in that, The steel slag powder should contain no less than 25% Fe2O3, have a fineness of no less than 300 mesh, and a moisture content of no more than 1%.

10. The method for making slag powder-steel slag powder cementitious system mortar according to claim 7, characterized in that, The mass ratio of slag powder, steel slag powder, quartz sand and water is 7:3:14:4.

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