High-performance environment-friendly curing agent based on industrial solid waste and nano material and preparation method thereof

Abstract

The invention discloses a high-performance environment-friendly curing agent based on industrial solid waste and a nano material, which comprises the following components in parts by weight: 50-70 parts of an industrial solid waste-based cementing material, 5-15 parts of a nano reinforcing material, 3-8 parts of a bio-based dispersing agent, 10-20 parts of a composite exciting agent and 5-10 parts of a micro-expanding agent, wherein the industrial solid waste-based cementing material is a mixture of steel slag, red mud and ardealite; wherein the nano reinforcing material is formed by compounding hydrophobic nano silicon dioxide and a carbon nano tube; wherein the bio-based dispersant is a loofah sponge extract; wherein the composite exciting agent is a compound of sodium sulfate, sodium silicate and sodium gluconate; wherein the micro-expanding agent is a compound of magnesium oxide and alunite. According to the high-performance environment-friendly curing agent based on the industrial solid waste and the nano material, the compressive strength of the curing agent can be improved and the shrinkage cracking of the curing agent can be reduced while the high flowability of the fluid-state cured soil is ensured.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a high-performance environmentally friendly curing agent based on industrial solid waste and nanomaterials and its preparation method. Background Technology

[0002] Fluidized solidified soil is a special soil improvement technology that involves treating traditional soil with a special solidifying agent to form a hard, solid structure. The solidifying agent is the key material determining the performance of fluidized solidified soil. Traditional soil solidifying agents often rely on cement or lime, which suffers from high carbon emissions, large shrinkage rates, and low solid waste utilization. Existing technologies, such as CN109293327B, use industrial solid wastes like steel slag and phosphogypsum, but suffer from low early strength and insufficient fluidity. CN112142406B improves fluidity by adding dispersants, but relies on chemically synthesized materials, resulting in insufficient environmental friendliness. Therefore, how to improve the compressive strength and reduce shrinkage cracking of fluidized solidified soil while maintaining its high fluidity is a pressing problem that needs to be solved. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a high-performance environmentally friendly curing agent based on industrial solid waste and nanomaterials and its preparation method, which addresses the shortcomings of the prior art. The high-performance environmentally friendly curing agent based on industrial solid waste and nanomaterials of the present invention can improve the compressive strength and reduce the shrinkage and cracking of the fluidized solidified soil while ensuring its high fluidity.

[0004] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows: A high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials, comprising the following components by weight: 50-70 parts of industrial solid waste-based cementitious material, 5-15 parts of nano-reinforcing material, 3-8 parts of bio-based dispersant, 10-20 parts of composite activator, and 5-10 parts of micro-expansion agent; wherein the industrial solid waste-based cementitious material is a mixture of steel slag, red mud, and phosphogypsum; wherein the nano-reinforcing material is a composite of hydrophobic nano-silica and carbon nanotubes; wherein the bio-based dispersant is loofah extract; wherein the composite activator is a composite of sodium sulfate, sodium silicate, and sodium gluconate; and wherein the micro-expansion agent is a composite of magnesium oxide and alunite.

[0005] In the above scheme, the high-performance environmentally friendly curing agent comprises the following components by weight: 60-65 parts of industrial solid waste-based cementitious material, 10-15 parts of nano-reinforcing material, 5-8 parts of bio-based dispersant, 15-20 parts of composite activator, and 8-10 parts of micro-expansion agent.

[0006] In the above scheme, the industrial solid waste-based cementitious material, by weight, comprises: 30-40 parts steel slag, 10-20 parts red mud, and 10-15 parts phosphogypsum; wherein the steel slag has a particle size ≤50μm and a specific surface area ≥450m². 2 / kg; wherein the Fe2O3 content in the red mud is ≤25%; wherein the CaSO4·2H2O content in the phosphogypsum is ≥90%.

[0007] In the above scheme, the iron content of the steel slag is ≤0.3% after magnetic separation to remove iron, and it is then subjected to microwave activation treatment; wherein the power of the microwave activation treatment is 600-1000W and the time is 5-30min.

[0008] In the above scheme, the carbon nanotubes need to be oxidized with nitric acid before use, and the surface carboxyl content is ≥5 mmol / g; wherein the concentration of nitric acid is 20-40%, and the oxidation treatment time is 30-60 min.

[0009] In the above scheme, the mass ratio of the hydrophobic nano-silica to the carbon nanotube in the nano-reinforcing material is (2-5):1; wherein the particle size of the hydrophobic nano-silica is 20-50 nm, and the aspect ratio of the carbon nanotube is ≥1000.

[0010] In the above scheme, the preparation method of the loofah extract is as follows: the loofah is crushed to a particle size ≤5mm, extracted with an ethanol-water mixed solvent at 50-70℃ for 2-3h, concentrated and dried to obtain the extract; wherein the volume ratio of ethanol to water in the ethanol-water mixed solvent is 1:(2-4); wherein the polysaccharide content of the loofah extract is ≥60%.

[0011] In the above scheme, the mass ratio of sodium sulfate to sodium silicate in the composite activator is (1-3):1; the mass of sodium gluconate is 0.5%-2% of the sum of the masses of sodium sulfate and sodium silicate.

[0012] In the above scheme, the mass ratio of magnesium oxide to alunite in the micro-expansion agent is (1-3):1; wherein the activity of the magnesium oxide is ≥80%, and the alunite contains Al6(SO4)3(OH) 12 • 6H2O content ≥ 85%.

[0013] The above-mentioned method for preparing high-performance environmentally friendly solidifying agents based on industrial solid waste and nanomaterials includes the following steps: (1) Steel slag, red mud, and phosphogypsum are ground separately and then mixed. The mixture is then microwave-activated under a protective gas atmosphere to obtain an industrial solid waste-based cementitious material; wherein the specific surface area of ​​the steel slag, red mud, and phosphogypsum after grinding is ≥450 m². 2 / kg; wherein the microwave activation is carried out under nitrogen or argon protection at a temperature of 200-300°C for 5-20 minutes; (2) Hydrophobic nano-silica and carbon nanotubes are mixed and then ultrasonically dispersed to obtain nano-reinforced materials; wherein the frequency of the ultrasonic wave is 30-50 kHz, the power is 200-400 W, and the time is 20-40 min. (3) The obtained industrial solid waste-based cementitious material and the obtained nano-reinforced material are premixed in a twin-screw mixer for a first time, and then bio-based dispersant, composite activator and micro-expansion agent are added and mixed for a second time; wherein the first time is 5 to 15 min and the second time is 10 to 20 min.

[0014] In this invention, steel slag provides gelling activity, while red mud and phosphogypsum regulate alkalinity and micro-expansion, forming a multi-stage activation-stabilization synergistic mechanism for solid waste. Microwave treatment at 200℃ under a protective gas atmosphere induces a solid-state diffusion reaction between free CaO and Fe2O3 in the steel slag, generating inert calcium iron oxide (Ca2Fe2O5), reducing f-CaO content and improving volume stability. Na2O dissolves from the red mud, creating a strongly alkaline environment that disrupts the Si-O-Si bond angles in the glassy mineral powder, releasing active SiO2 and Al2O3 to participate in hydration. SO4 in the phosphogypsum... 2- With Al in the activator 3+ The reaction produces needle-like ettringite (AFt), which counteracts the shrinkage.

[0015] In this invention, a nano-interface bonding-bridging enhancement mechanism is formed using hydrophobic nano-SiO2 (filling pores) and carboxylated carbon nanotubes (interface toughening). The ≡Si-O-CH3 groups on the surface of the hydrophobic nano-SiO2 hydrolyze to ≡Si-OH, which then reacts with Ca in the CSH gel. 2+ Ca-O-Si covalent bonds are formed; the oxidation treatment of carboxylated carbon nanotubes introduces -COOH / -OH, which reacts with Ca in the CSH gel. 2+ It forms ionic bonds, bridging cracks and improving toughness.

[0016] In this invention, β-glucan produced by the hydrolysis of loofah polysaccharide is adsorbed onto the edge of clay particles, and flocculation is inhibited through steric hindrance to form biodispersion, thereby replacing chemical water-reducing agents and exhibiting outstanding environmental friendliness.

[0017] In this invention, sodium gluconate is used to regulate coagulation and MgO / alum stone graded expansion to form a spatiotemporal matching mechanism of slowing-expansion. Sodium gluconate chelates Ca... 2+ This prolongs the hydration induction period of C3S, providing a time window for MgO expansion; the effective time of MgO is 0-72h, and the effective time of alunite is 7-28d, with graded expansion matching the shrinkage process.

[0018] Compared with existing technologies, the beneficial effects of this invention are: This invention provides a high-performance environmentally friendly curing agent based on industrial solid waste and nanomaterials. It takes industrial solid waste as the core and combines nano-reinforcing materials and bio-based dispersants to achieve a balance of high fluidity, high strength and low shrinkage of fluidized solidified soil through multi-level synergistic effects. Detailed Implementation

[0019] The technical solution of the present invention will be described in detail below with reference to specific embodiments. However, the described embodiments are only some embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a high-performance environmentally friendly curing agent based on industrial solid waste and nanomaterials, and its preparation method.

[0021] The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials comprises the following components by weight: 50-70 parts of industrial solid waste-based cementitious material, 5-15 parts of nano-reinforcing material, 3-8 parts of bio-based dispersant, 10-20 parts of composite activator, and 5-10 parts of micro-expansion agent; wherein the industrial solid waste-based cementitious material is a mixture of steel slag, red mud, and phosphogypsum; wherein the nano-reinforcing material is a composite of hydrophobic nano-silica and carbon nanotubes; wherein the bio-based dispersant is loofah extract; wherein the composite activator is a composite of sodium sulfate, sodium silicate, and sodium gluconate; and wherein the micro-expansion agent is a composite of magnesium oxide and alunite.

[0022] The preparation method of high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials is as follows: S1. Pretreatment of industrial solid waste: Steel slag, red mud, and phosphogypsum are ground separately to a specific surface area ≥450m². 2 / kg, mixed in proportion and then microwave activated to obtain industrial solid waste-based cementitious material; wherein microwave activation is carried out under nitrogen protection at a temperature of 200℃ for 10min; S2. Nano-reinforcing material composite: hydrophobic nano-silica and oxidized carbon nanotubes are mixed in an ultrasonic disperser (frequency 40kHz, power 300W) for 30min to obtain nano-reinforcing material; S3. Segmented mixing: industrial solid waste-based cementitious material and nano-reinforcing material are premixed in a twin-screw mixer for 10min, then bio-based dispersant, composite activator and micro-expansion agent are added, and mixing is continued for 15min until uniform.

[0023] In a specific embodiment, the steel slag used has a particle size ≤50μm and a specific surface area ≥450m². 2 / kg; Fe2O3 content in red mud ≤25%; CaSO4·2H2O content in phosphogypsum ≥90%; iron content in steel slag after magnetic separation is ≤0.3%, and it is then subjected to microwave activation treatment; the power of microwave activation treatment is 800W, and the time is 10min; Before use, carbon nanotubes need to be oxidized with nitric acid to achieve a surface carboxyl content of ≥5 mmol / g; the concentration of nitric acid is 30%, and the oxidation treatment time is 40 min. The hydrophobic nano-silica has a particle size of 20–50 nm and the carbon nanotubes have an aspect ratio of ≥1000. The preparation method of loofah sponge extract is as follows: loofah sponge is crushed to a particle size ≤5mm, extracted with an ethanol-water mixed solvent at 60℃ for 2h, concentrated and dried to obtain the extract; wherein the volume ratio of ethanol to water in the ethanol-water mixed solvent is 1:3; and the polysaccharide content of the loofah sponge extract is ≥60%. Magnesium oxide has an activity ≥80%, and Al6(SO4)3(OH) in alunite. 12 • 6H2O content ≥ 85%; Performance testing in the specific implementation method: The soil stabilizer of the examples and comparative examples was applied with an addition of 10% of the base soil mass, and the water-to-solid ratio was 0.4. The spread of the stabilized soil mixture was tested using a concrete slump cone. The compressive strength and volume shrinkage rate of the stabilized soil were tested in accordance with the "JGJ / T70-2009 Basic Performance Test Methods for Building Mortar".

[0024] Example 1 The high-performance, environmentally friendly curing agent based on industrial solid waste and nanomaterials comprises the following components by weight: Industrial solid waste-based cementitious material: magnetically separated steel slag (iron content 0.25%, specific surface area 480 m²) 2 35 parts ( / kg), 15 parts red mud (Fe2O3·22.5%), and 12 parts phosphogypsum (CaSO4·2H2O 92%); Nanomaterial reinforcement: 7.5 parts of hydrophobic nano-SiO2 (20nm) and 2.5 parts of carboxylated carbon nanotubes (aspect ratio 1200); Bio-based dispersant: 5 parts of loofah extract (68% polysaccharide); Composite activator: 12 parts sodium sulfate, 6 parts sodium silicate, and 0.18 parts sodium gluconate; Micro-expansion agent: 4 parts active magnesium oxide (85%), 4 parts alum stone.

[0025] Example 2 The high-performance, environmentally friendly curing agent based on industrial solid waste and nanomaterials comprises the following components by weight: Industrial solid waste-based cementitious material: magnetically separated steel slag (iron content 0.25%, specific surface area 480 m²) 2 30 parts ( / kg) of red mud (Fe2O3·22.5%), 20 parts of phosphogypsum (CaSO4·2H2O 92%), and 15 parts of phosphogypsum. Nanomaterial reinforcement: 7.5 parts of hydrophobic nano-SiO2 (20nm) and 2.5 parts of carboxylated carbon nanotubes (aspect ratio 1200); Bio-based dispersant: 5 parts of loofah extract (68% polysaccharide); Composite activator: 12 parts sodium sulfate, 6 parts sodium silicate, and 0.18 parts sodium gluconate; Micro-expansion agent: 4 parts active magnesium oxide (85%), 4 parts alum stone.

[0026] Example 3 The high-performance, environmentally friendly curing agent based on industrial solid waste and nanomaterials comprises the following components by weight: Industrial solid waste-based cementitious material: magnetically separated steel slag (iron content 0.25%, specific surface area 480 m²) 2 35 parts ( / kg), 15 parts red mud (Fe2O3·22.5%), and 12 parts phosphogypsum (CaSO4·2H2O 92%); Nanomaterial reinforcement: 10 parts of hydrophobic nano-SiO2 (20nm) and 5 parts of carboxylated carbon nanotubes (aspect ratio 1200); Bio-based dispersant: 5 parts of loofah extract (68% polysaccharide); Composite activator: 12 parts sodium sulfate, 6 parts sodium silicate, and 0.18 parts sodium gluconate; Micro-expansion agent: 4 parts active magnesium oxide (85%), 4 parts alum stone.

[0027] Example 4 The high-performance, environmentally friendly curing agent based on industrial solid waste and nanomaterials comprises the following components by weight: Industrial solid waste-based cementitious material: magnetically separated steel slag (iron content 0.25%, specific surface area 480 m²) 2 35 parts ( / kg), 15 parts red mud (Fe2O3·22.5%), and 12 parts phosphogypsum (CaSO4·2H2O 92%); Nanomaterial reinforcement: 7.5 parts of hydrophobic nano-SiO2 (20nm) and 2.5 parts of carboxylated carbon nanotubes (aspect ratio 1200); Bio-based dispersant: 3 parts of loofah extract (68% polysaccharide); Composite activator: 12 parts sodium sulfate, 6 parts sodium silicate, and 0.18 parts sodium gluconate; Micro-expansion agent: 4 parts active magnesium oxide (85%), 4 parts alum stone.

[0028] Example 5 The high-performance, environmentally friendly curing agent based on industrial solid waste and nanomaterials comprises the following components by weight: Industrial solid waste-based cementitious material: magnetically separated steel slag (iron content 0.25%, specific surface area 480 m²) 2 35 parts ( / kg), 15 parts red mud (Fe2O3·22.5%), and 12 parts phosphogypsum (CaSO4·2H2O 92%); Nanomaterial reinforcement: 7.5 parts of hydrophobic nano-SiO2 (20nm) and 2.5 parts of carboxylated carbon nanotubes (aspect ratio 1200); Bio-based dispersant: 5 parts of loofah extract (68% polysaccharide); Composite activator: 10 parts sodium sulfate, 5 parts sodium silicate, and 0.15 parts sodium gluconate; Micro-expansion agent: 4 parts active magnesium oxide (85%), 4 parts alum stone.

[0029] Comparative Example 1 This comparative example is basically the same as Example 1, except that no nano-reinforcing materials were used.

[0030] Comparative Example 2 This comparative example is basically the same as Example 1, except that no bio-based dispersant was used.

[0031] Comparative Example 3 This comparative example is basically the same as Example 1, except that no micro-expansion agent was used.

[0032] The performance test results of the curing agents obtained in each embodiment and comparative example are shown in Table 1: Table 1. Performance test results of the curing agents obtained from the examples and comparative examples.

[0033] As shown in Table 1, the compressive strength of Comparative Example 1 (without nano-reinforcing material) was significantly reduced due to the lack of pore filling and interface toughening; the fluidity of Comparative Example 2 (without bio-based dispersant) was significantly reduced due to the lack of steric hindrance effect; and the shrinkage of Comparative Example 3 (without micro-expanding agent) was significantly increased due to the lack of graded expansion to match shrinkage volume.

[0034] In summary, the high-performance environmentally friendly curing agent based on industrial solid waste and nanomaterials provided by this invention can improve the compressive strength and reduce shrinkage cracking of fluidized solidified soil while ensuring its high fluidity.

[0035] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concept, should be covered within the scope of protection of the present invention.

Claims

1. A high-performance, environmentally friendly curing agent based on industrial solid waste and nanomaterials, characterized in that, By weight, it comprises the following components: 50-70 parts of industrial solid waste-based cementitious material, 5-15 parts of nano-reinforcing material, 3-8 parts of bio-based dispersant, 10-20 parts of composite activator, and 5-10 parts of micro-expansion agent; wherein the industrial solid waste-based cementitious material is a mixture of steel slag, red mud, and phosphogypsum; wherein the nano-reinforcing material is a composite of hydrophobic nano-silica and carbon nanotubes; wherein the bio-based dispersant is loofah extract; wherein the composite activator is a composite of sodium sulfate, sodium silicate, and sodium gluconate; and wherein the micro-expansion agent is a composite of magnesium oxide and alunite.

2. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The high-performance environmentally friendly curing agent comprises the following components by weight: 60-65 parts of industrial solid waste-based cementitious material, 10-15 parts of nano-reinforcing material, 5-8 parts of bio-based dispersant, 15-20 parts of composite activator, and 8-10 parts of micro-expansion agent.

3. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The industrial solid waste-based cementitious material comprises, by weight, 30-40 parts steel slag, 10-20 parts red mud, and 10-15 parts phosphogypsum; wherein the steel slag has a particle size ≤50μm and a specific surface area ≥450m². 2 / kg; wherein the Fe2O3 content in the red mud is ≤25%; wherein the CaSO4·2H2O content in the phosphogypsum is ≥90%.

4. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The steel slag, after being magnetically separated to remove iron, has an iron content of ≤0.3% and is then subjected to microwave activation treatment; wherein the power of the microwave activation treatment is 600-1000W and the time is 5-30min.

5. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The carbon nanotubes need to be oxidized with nitric acid before use, and the surface carboxyl content is ≥5 mmol / g; wherein the concentration of nitric acid is 20% to 40%, and the oxidation treatment time is 30 to 60 min.

6. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The mass ratio of the hydrophobic nano-silica to the carbon nanotube in the nano-reinforcing material is (2-5):1; wherein the particle size of the hydrophobic nano-silica is 20-50 nm, and the aspect ratio of the carbon nanotube is ≥1000.

7. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The preparation method of the loofah sponge extract is as follows: the loofah sponge is crushed to a particle size ≤5mm, extracted with an ethanol-water mixed solvent at 50-70℃ for 2-3h, concentrated and dried to obtain the extract; wherein the volume ratio of ethanol to water in the ethanol-water mixed solvent is 1:(2-4); wherein the polysaccharide content of the loofah sponge extract is ≥60%.

8. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The mass ratio of sodium sulfate to sodium silicate in the composite activator is (1-3):1; the mass of sodium gluconate is 0.5%-2% of the sum of the masses of sodium sulfate and sodium silicate.

9. The high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to claim 1, characterized in that, The mass ratio of magnesium oxide to alunite in the micro-expansion agent is (1-3):1; wherein the activity of the magnesium oxide is ≥80%, and the alunite contains Al6(SO4)3(OH) 12 • 6H2O content ≥ 85%.

10. The preparation method of the high-performance environmentally friendly solidifying agent based on industrial solid waste and nanomaterials according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Steel slag, red mud, and phosphogypsum are ground separately and then mixed. The mixture is then microwave-activated under a protective gas atmosphere to obtain an industrial solid waste-based cementitious material; wherein the specific surface area of ​​the steel slag, red mud, and phosphogypsum after grinding is ≥450 m². 2 / kg; wherein the microwave activation is carried out under a protective atmosphere at a temperature of 200-300°C for 5-20 minutes; (2) Hydrophobic nano-silica and carbon nanotubes are mixed and then ultrasonically dispersed to obtain nano-reinforced materials; wherein the frequency of the ultrasonic wave is 30-50 kHz, the power is 200-400 W, and the time is 20-40 min. (3) The obtained industrial solid waste-based cementitious material and the obtained nano-reinforced material are premixed in a twin-screw mixer for a first time, and then bio-based dispersant, composite activator and micro-expansion agent are added and mixed for a second time; wherein the first time is 5 to 15 min and the second time is 10 to 20 min.

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