Copper tailings-based high-strength grouting material and preparation method thereof
By using self-healing microcapsule reinforcing agents in copper tailings-based high-strength grouting materials, and by utilizing magnesium oxide expanding agents and humic acid-modified cellulose wall materials, the problems of chloride ion penetration and crack self-healing in cement-based grouting materials in coastal environments have been solved, achieving a synergistic improvement in high strength and self-healing capabilities.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANXI SHUNWANG CONSTR ENG CO LTD
- Filing Date
- 2026-05-21
- Publication Date
- 2026-06-19
AI Technical Summary
In harsh coastal and near-shore environments, existing cement-based grouting materials are threatened by chloride ion penetration, leading to steel corrosion and microcrack propagation. Furthermore, existing microcapsules have a sluggish response and low self-healing efficiency. The lack of synergistic design between chloride ion blocking and crack self-healing systems results in a loss of mechanical properties.
High-strength grouting material based on copper tailings was used. A self-healing microcapsule reinforcing agent was prepared. Magnesium oxide expanding agent and ettringite derivatives were used to provide spatial support. Ethyl cellulose wall material was modified to form a hydrophobic-ionic dual-response layer. Brown humic acid was used to strengthen the microcapsule wall material to chelate heavy metal ions and enhance adhesion and self-healing ability.
It achieves precise fixation of chloride ions and crack repair in high salt spray environment, enhances the strength and self-healing performance of grout, maintains high mechanical properties, and synergistically solves the problems of chloride ion erosion, heavy metal stabilization and crack self-repair.
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Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention belongs to the field of grout preparation technology, and particularly relates to a copper tailings-based high-strength grout and its preparation method. Background Technology
[0002] In harsh coastal and near-shore engineering environments, the performance shortcomings of traditional cement-based grouting materials are particularly prominent. The threat of chloride ion penetration from high salt spray environments is the primary challenge. It not only directly corrodes the steel bars, causing the passivation film to break down and accelerating steel bar corrosion, but also induces and exacerbates the generation and propagation of microcracks inside the matrix due to salt crystallization pressure and frequent wet-dry cycles.
[0003] While existing technologies have attempted to use physically encapsulated microcapsules for self-healing, these microcapsules generally exhibit sluggish response in the highly alkaline environment created by cement hydration. This makes it difficult to release the repair components promptly and accurately at the critical moment when corrosive media penetrate the cracks, resulting in low repair efficiency for cracks, especially fine cracks. Furthermore, existing functional systems for chloride ion blocking, heavy metal stabilization, and crack self-healing are usually independent and lack synergistic design. This not only increases the complexity of the formulation but also makes the grout material more susceptible to significant loss of overall mechanical properties due to interfacial compatibility issues. Therefore, there is an urgent need to develop a novel grouting technology that can synergistically address the triple challenges of chloride ion corrosion, heavy metal leaching, and crack self-healing, while maintaining high mechanical properties in harsh coastal environments. Summary of the Invention
[0004] To address the aforementioned technical deficiencies, this invention presents a copper tailings-based high-strength grouting material and its preparation method. By adding a self-healing microcapsule reinforcing agent to the grouting material, the resulting grouting material exhibits high strength and excellent self-healing properties.
[0005] A method for preparing a high-strength grouting material based on copper tailings includes the following steps: S1: Preparation of self-healing capsule core material Metakaolin and nano-alumina were ball-milled with anhydrous ethanol as the matrix, filtered and dried to obtain activated composite powder. The activated composite powder was mixed evenly with water glass solution, NaOH was added to adjust the pH and age it, then filtered, dried and pulverized to obtain chloride ion adsorbent. Sodium aluminate, anhydrous calcium sulfate and water were mixed evenly, NaOH solution was added to maintain the pH, stirred and then pressure filtered. The filter cake was collected, washed and pulverized to obtain expansion control agent. S2: Preparation of self-healing microcapsule enhancers Ethyl cellulose particles and humic acid are dissolved in anhydrous ethanol to obtain a microcapsule wall material solution. Magnesium oxide expansion agent, expansion control agent, sludge solidifying agent and chloride ion adsorbent are stirred and mixed evenly to obtain microcapsule mixed core material powder. The microcapsule mixed core material powder is added to a disc granulator and the microcapsule wall material solution is sprayed for granulation to obtain a self-healing microcapsule reinforcing agent. S3: Preparation of grouting material Silicate cement, sulfoaluminate cement, fly ash, calcium sulfate and calcium carbonate are dry-mixed to obtain grouting base material. River sand and copper tailings are screened to obtain screened material. Polycarboxylate superplasticizer is dissolved in deionized water to obtain superplasticizer solution. Grouting base material, screened material, superplasticizer solution, self-healing microcapsule reinforcing agent and water are mixed evenly to obtain high-strength grouting material.
[0006] Furthermore, the preparation of the self-healing capsule core material in step S1 specifically includes the following steps: S1.1: Place 45-50 parts by weight of metakaolin and 4-5 parts by weight of nano-alumina in a ball mill, add 150-180 parts by weight of anhydrous ethanol as the dispersion medium, and ball mill at 350-400 r / min for 2-3 hours to obtain a uniform slurry. Filter the uniform slurry and dry it to constant weight to obtain activated composite powder. Mix the activated composite powder with 30-35 parts by weight of water glass solution with a modulus of 3.2-3.5, stir at 500-650 r / min for 10-15 minutes at room temperature, then add NaOH to adjust the pH to 14, age for 10-12 hours, filter, place the filter cake in a vacuum drying oven to dry to constant weight, pulverize and pass through a 600-625 mesh sieve to obtain chloride ion adsorbent; S1.2: Add 200-250 parts by weight of water to a container, heat to 40-45℃ and keep warm, then add 25-30 parts by weight of sodium aluminate and 35-40 parts by weight of anhydrous calcium sulfate, stir at 400-450 r / min for 15-20 minutes, then add 10% NaOH solution to maintain pH at 11-12, and continue stirring for 3-4 hours to obtain the swelling control agent solution; S1.3: Transfer the swelling control agent solution to a plate and frame filter press for filtration, collect the filter cake, wash it with clean water 3-4 times, dry it, and then crush it to a particle size of 10-50μm to obtain the swelling control agent.
[0007] Furthermore, the preparation of the self-healing microcapsule enhancer in step S2 specifically includes the following steps: S2.1: Place ethyl cellulose particles, humic acid and anhydrous ethanol in a container and stir at a stirring speed of 800-1000 r / min until the solids are completely dissolved to obtain a microcapsule wall material solution. S2.2: Place 65-70 parts by weight of magnesium oxide expanding agent, 35-40 parts by weight of expansion control agent, 40-45 parts by weight of sludge solidifying agent and chloride ion adsorbent in a mixer and stir at a stirring speed of 400-600 r / min until the mixture presents a uniform color to obtain microcapsule mixed core material powder. S2.3: Pour the microcapsule mixed core material powder into a disc granulator, set the rotation speed of the disc granulator to 65-75 r / min and the tilt angle to 45-50°, and continuously spray the microcapsule wall material solution onto the surface of the microcapsule mixed core material powder during the rotation process. The spraying speed is 0.1-0.3 L / min, and the total amount of microcapsule wall material solution sprayed is 45-50% of the microcapsule mixed core material powder, thus obtaining a self-healing microcapsule reinforcing agent.
[0008] Further, step S3, preparing the grouting material, specifically includes the following steps: S3.1: Add 600-650 parts by weight of 52.5 grade silicate cement, 120-150 parts by weight of sulfoaluminate cement, 50-60 parts by weight of fly ash, 25-30 parts by weight of calcium sulfate and 25-30 parts by weight of calcium carbonate into a mixer and dry mix at a speed of 45-50 r / min for 12-15 minutes to obtain grouting base material; S3.2: Place 400-450 parts by weight of river sand and 60-80 parts by weight of copper tailings in a screening machine with an aperture of 4-6 mm and vibrate and screen for 5-7 minutes to obtain the screened material. Dissolve 2.5-3 parts by weight of polycarboxylate superplasticizer in 10-15 parts by weight of deionized water to obtain a superplasticizer solution. S3.3: Place the grouting base material obtained in step S3.1 and the sieved material obtained in step S3.2 into a mixer and dry mix for 3-5 minutes. Then add the water-reducing agent solution prepared in step S3.2, 2-3% of the total mass of the grouting base material, the self-healing microcapsule reinforcing agent, and 300-350 parts by weight of water. Stir evenly at a speed of 180-200 r / min to obtain high-strength grouting material.
[0009] Further, in step S2.1, the concentration of ethyl cellulose in the microcapsule wall material solution is 50-60 g / L, and the concentration of humic acid is 1-2 g / L.
[0010] Further, the preparation method of the sludge solidifying agent in step S2.2 is as follows: it is prepared by thoroughly mixing 4-8 parts of sodium polyacrylate, 1-2 parts of polyacrylamide, 0.5-1 parts of polycarboxylate superplasticizer, 2-5 parts of water glass, 3-8 parts of silicate cement, 5-10 parts of fly ash, 18-28 parts of ferrous sulfate, and 15-25 parts of zeolite.
[0011] Furthermore, the fineness modulus of the river sand in step S3.2 is 2.3-2.6.
[0012] Furthermore, in step 3.2, the apparent density of the copper tailings is 2700-2900 kg / m3, the mass fraction of stone powder is 12.5-14%, and the fineness modulus is 0.8-0.9.
[0013] A copper tailings-based high-strength grouting material is prepared by the above-mentioned method for preparing a copper tailings-based high-strength grouting material.
[0014] The beneficial effects of this invention are: 1. This application designs a self-healing microcapsule reinforcing agent using ethyl cellulose and humic acid as wall materials through core material composition design. The microcapsule core material contains magnesium oxide expansion agent and ettringite derivative as the main expansion control agent components. When magnesium oxide comes into contact with water, it expands rapidly to provide space support for the growth of ettringite crystals, while the ettringite derivative continuously absorbs water and expands to fill the depth area of the crack. After modification with humic acid, the ethyl cellulose wall material forms a hydrophobic-ionic dual-response layer, which blocks water penetration under normal conditions. When chloride-containing corrosive liquid seeps into the crack, the wall material generates swelling pores due to the ionization of carboxyl groups in humic acid, and the chloride ion adsorbent component is released, thereby accurately fixing the chloride ions and preventing them from corroding the cement. Furthermore, the prepared self-healing microcapsule reinforcing agent has a rough texture on its surface, which can enhance the adhesion between the microcapsules and the grouting material. The prepared grouting material has high strength after curing.
[0015] 2. This application introduces humic acid into the wall material of the self-healing microcapsule reinforcer. The high-density phenolic hydroxyl and carboxyl groups in its molecular structure can strongly chelate the heavy metal ions dissolved from copper tailings and the calcium ions from cement, making the components of the grouting material more tightly bound to the microcapsules. At the same time, the humic acid molecules can not only embed into the ethyl cellulose chain segments through π-π conjugation, enhancing the microcapsules' resistance to the stirring and shearing forces of the grouting material, but also its pH response characteristics allow the wall material to remain dense in an alkaline environment. The prepared grouting material has high strength and better self-healing ability after curing. Detailed Implementation
[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1
[0017] A method for preparing a high-strength grouting material based on copper tailings includes the following steps: S1: Preparation of self-healing capsule core material S1.1: 45 parts by weight of metakaolin and 4 parts by weight of nano-alumina were placed in a ball mill, and 150 parts by weight of anhydrous ethanol was added as a dispersion medium. The mixture was ball-milled at 350 r / min for 2 hours to obtain a uniform slurry. The uniform slurry was filtered and dried to constant weight to obtain activated composite powder. The activated composite powder was mixed with 30 parts by weight of water glass solution with a modulus of 3.2 and stirred at 500 r / min for 10 minutes at room temperature. Then, NaOH was added to adjust the pH to 14. After aging for 10 hours, the mixture was filtered. The filter cake was placed in a vacuum drying oven and dried to constant weight. It was then pulverized and passed through a 600-mesh sieve to obtain a chloride ion adsorbent. S1.2: Add 200 parts by weight of water to a container, heat to 40°C and keep warm. Then add 25 parts by weight of sodium aluminate and 35 parts by weight of anhydrous calcium sulfate. Stir at 400 r / min for 15 minutes. Then add 10% NaOH solution to maintain pH at 11. Continue stirring for 3 hours to obtain the swelling control agent solution. S1.3: Transfer the expansion control agent solution to a plate and frame filter press for filtration, collect the filter cake, wash it three times with clean water, dry it, and then crush it to a particle size of 10μm to obtain the expansion control agent.
[0018] S2: Preparation of self-healing microcapsule enhancers S2.1: Place ethyl cellulose particles, humic acid and anhydrous ethanol in a container and stir at 800 r / min until the solids are completely dissolved to obtain a microcapsule wall material solution. The concentration of ethyl cellulose in the microcapsule wall material solution is 50 g / L and the concentration of humic acid is 1 g / L. S2.2: Place 65 parts by weight of magnesium oxide expanding agent, 35 parts by weight of expansion control agent, 40 parts by weight of sludge solidifying agent and chloride ion adsorbent in a mixer and stir at a stirring speed of 400 r / min until the mixture presents a uniform color to obtain microcapsule mixed core material powder. The sludge solidifying agent is prepared by thoroughly mixing 4 parts by weight of sodium polyacrylate, 1 part by weight of polyacrylamide, 0.5 parts by weight of polycarboxylate superplasticizer, 2 parts by weight of water glass, 3 parts by weight of silicate cement, 5 parts by weight of fly ash, 18 parts by weight of ferrous sulfate and 15 parts by weight of zeolite. S2.3: Pour the microcapsule mixed core material powder into a disc granulator, set the rotation speed of the disc granulator to 65 r / min and the tilt angle to 45°, and continuously spray the microcapsule wall material solution onto the surface of the microcapsule mixed core material powder during the rotation process. The spraying speed is 0.1 L / min, and the total amount of microcapsule wall material solution sprayed is 45% of the microcapsule mixed core material powder, thus obtaining a self-healing microcapsule reinforcing agent.
[0019] S3: Preparation of grouting material S3.1: Add 600 parts by weight of grade 52.5 silicate cement, 120 parts by weight of sulfoaluminate cement, 50 parts by weight of fly ash, 25 parts by weight of calcium sulfate and 25 parts by weight of calcium carbonate into a mixer and dry mix at a speed of 45 r / min for 12 minutes to obtain grouting base material. S3.2: 400 parts by weight of river sand with a fineness modulus of 2.3 and 60 parts by weight of copper tailings are placed in a 4mm aperture screening machine and vibrated for 5 minutes to obtain the screened material, wherein the apparent density of the copper tailings is 2700 kg / m³. 3 The copper tailings contained 12.5% stone powder by mass and 0.8 fineness modulus. 2.5 parts by weight of polycarboxylate superplasticizer were dissolved in 10 parts by weight of deionized water to obtain a superplasticizer solution. S3.3: Place the grouting base material obtained in step S3.1 and the sieved material obtained in step S3.2 into a mixer and dry mix for 3 minutes. Then add the water-reducing agent solution prepared in step S3.2, 2% of the total mass of the grouting base material, the self-healing microcapsule reinforcing agent, and 300 parts by weight of water. Stir evenly at a speed of 180 r / min to obtain high-strength grouting material. Example 2
[0020] A method for preparing a high-strength grouting material based on copper tailings includes the following steps: S1: Preparation of self-healing capsule core material S1.1: 50 parts by weight of metakaolin and 5 parts by weight of nano-alumina were placed in a ball mill, and 180 parts by weight of anhydrous ethanol was added as the dispersion medium. The mixture was ball-milled at 350 r / min for 2 hours to obtain a uniform slurry. The uniform slurry was filtered and dried to constant weight to obtain activated composite powder. The activated composite powder was mixed with 35 parts by weight of water glass solution with a modulus of 3.2 and stirred at 500 r / min for 10 minutes at room temperature. Then, NaOH was added to adjust the pH to 14. After aging for 10 hours, the mixture was filtered. The filter cake was placed in a vacuum drying oven and dried to constant weight. It was then pulverized and passed through a 600-mesh sieve to obtain a chloride ion adsorbent. S1.2: Add 250 parts by weight of water to a container, heat to 40°C and keep warm. Then add 30 parts by weight of sodium aluminate and 40 parts by weight of anhydrous calcium sulfate in sequence. Stir at 400 r / min for 15 minutes. Then add 10% NaOH solution to maintain pH at 11 and continue stirring for 3 hours to obtain the swelling control agent solution. S1.3: Transfer the expansion control agent solution to a plate and frame filter press for filtration, collect the filter cake, wash it three times with clean water, dry it, and then crush it to a particle size of 10μm to obtain the expansion control agent.
[0021] S2: Preparation of self-healing microcapsule enhancers S2.1: Place ethyl cellulose particles, humic acid and anhydrous ethanol in a container and stir at 800 r / min until the solids are completely dissolved to obtain a microcapsule wall material solution. The concentration of ethyl cellulose in the microcapsule wall material solution is 60 g / L and the concentration of humic acid is 2 g / L. S2.2: Place 70 parts by weight of magnesium oxide expanding agent, 40 parts by weight of expansion control agent, 45 parts by weight of sludge solidifying agent and chloride ion adsorbent in a mixer and stir at a stirring speed of 400 r / min until the mixture presents a uniform color to obtain microcapsule mixed core material powder. The sludge solidifying agent is prepared by thoroughly mixing 6 parts by weight of sodium polyacrylate, 1.5 parts by weight of polyacrylamide, 0.8 parts by weight of polycarboxylate superplasticizer, 6 parts by weight of water glass, 5 parts by weight of silicate cement, 8 parts by weight of fly ash, 24 parts by weight of ferrous sulfate and 20 parts by weight of zeolite. S2.3: Pour the microcapsule mixed core material powder into a disc granulator, set the rotation speed of the disc granulator to 65 r / min and the tilt angle to 45°, and continuously spray the microcapsule wall material solution onto the surface of the microcapsule mixed core material powder during the rotation process. The spraying speed is 0.1 L / min, and the total amount of microcapsule wall material solution sprayed is 50% of the microcapsule mixed core material powder, thus obtaining a self-healing microcapsule reinforcing agent.
[0022] S3: Preparation of grouting material S3.1: Add 650 parts by weight of grade 52.5 silicate cement, 150 parts by weight of sulfoaluminate cement, 60 parts by weight of fly ash, 30 parts by weight of calcium sulfate and 30 parts by weight of calcium carbonate into a mixer and dry mix at a speed of 45 r / min for 12 minutes to obtain grouting base material. S3.2: 450 parts by weight of river sand with a fineness modulus of 2.3 and 80 parts by weight of copper tailings are placed in a 4mm aperture screening machine and vibrated for 5 minutes to obtain the screened material, wherein the apparent density of the copper tailings is 2700 kg / m³. 3 The copper tailings contained 12.5% stone powder by mass and 0.8 fineness modulus. Three parts by weight of polycarboxylate superplasticizer were dissolved in 10 parts by weight of deionized water to obtain a superplasticizer solution. S3.3: Place the grouting base material obtained in step S3.1 and the sieved material obtained in step S3.2 into a mixer and dry mix for 3 minutes. Then add the water-reducing agent solution prepared in step S3.2, 3% of the total mass of the grouting base material, the self-healing microcapsule reinforcing agent, and 350 parts by weight of water. Stir evenly at a speed of 180 r / min to obtain high-strength grouting material. Example 3
[0023] A method for preparing a high-strength grouting material based on copper tailings includes the following steps: S1: Preparation of self-healing capsule core material S1.1: 45 parts by weight of metakaolin and 4 parts by weight of nano-alumina were placed in a ball mill, and 150 parts by weight of anhydrous ethanol was added as a dispersion medium. The mixture was ball-milled at 400 r / min for 3 hours to obtain a uniform slurry. The uniform slurry was filtered and dried to constant weight to obtain activated composite powder. The activated composite powder was mixed with 35 parts by weight of water glass solution with a modulus of 3.5 and stirred at 650 r / min for 15 minutes at room temperature. Then, NaOH was added to adjust the pH to 14. After aging for 12 hours, the mixture was filtered. The filter cake was placed in a vacuum drying oven and dried to constant weight. It was then pulverized and passed through a 625 mesh sieve to obtain a chloride ion adsorbent. S1.2: Add 200 parts by weight of water to a container, heat to 45°C and keep warm. Then add 25 parts by weight of sodium aluminate and 35 parts by weight of anhydrous calcium sulfate. Stir at 450 r / min for 20 minutes. Then add 10% NaOH solution to maintain pH at 12 and continue stirring for 4 hours to obtain the swelling control agent solution. S1.3: Transfer the expansion control agent solution to a plate and frame filter press for filtration, collect the filter cake, wash it 4 times with clean water, dry it, and then crush it to a particle size of 50μm to obtain the expansion control agent.
[0024] S2: Preparation of self-healing microcapsule enhancers S2.1: Place ethyl cellulose particles, humic acid and anhydrous ethanol in a container and stir at 1000 r / min until the solids are completely dissolved to obtain a microcapsule wall material solution. The concentration of ethyl cellulose in the microcapsule wall material solution is 50 g / L and the concentration of humic acid is 1 g / L. S2.2: Place 65 parts by weight of magnesium oxide expanding agent, 35 parts by weight of expansion control agent, 40 parts by weight of sludge solidifying agent and chloride ion adsorbent in a mixer and stir at a stirring speed of 600 r / min until the mixture presents a uniform color to obtain microcapsule mixed core material powder. The sludge solidifying agent is prepared by thoroughly mixing 8 parts by weight of sodium polyacrylate, 2 parts by weight of polyacrylamide, 1 part by weight of polycarboxylate superplasticizer, 5 parts by weight of water glass, 8 parts by weight of silicate cement, 10 parts by weight of fly ash, 28 parts by weight of ferrous sulfate and 25 parts by weight of zeolite. S2.3: Pour the microcapsule mixed core material powder into a disc granulator, set the rotation speed of the disc granulator to 75 r / min and the tilt angle to 50°, and continuously spray the microcapsule wall material solution onto the surface of the microcapsule mixed core material powder during the rotation process. The spraying speed is 0.3 L / min, and the total amount of microcapsule wall material solution sprayed is 50% of the microcapsule mixed core material powder, thus obtaining a self-healing microcapsule reinforcing agent.
[0025] S3: Preparation of grouting material S3.1: Add 600 parts by weight of 52.5 grade silicate cement, 120 parts by weight of sulfoaluminate cement, 50 parts by weight of fly ash, 25 parts by weight of calcium sulfate and 25 parts by weight of calcium carbonate into a mixer and dry mix at a speed of 50 r / min for 15 minutes to obtain grouting base material. S3.2: 400 parts by weight of river sand with a fineness modulus of 2.3 and 60 parts by weight of copper tailings are placed in a 6mm aperture screening machine and vibrated for 7 minutes to obtain the screened material, wherein the apparent density of the copper tailings is 2900 kg / m³. 3 The copper tailings contained 12.5% stone powder by mass and 0.9 fineness modulus. 2.5 parts by weight of polycarboxylate superplasticizer were dissolved in 10 parts by weight of deionized water to obtain a superplasticizer solution. S3.3: Place the grouting base material obtained in step S3.1 and the sieved material obtained in step S3.2 into a mixer and dry mix for 3 minutes. Then add the water-reducing agent solution prepared in step S3.2, 2% of the total mass of the grouting base material, the self-healing microcapsule reinforcing agent, and 300 parts by weight of water. Stir evenly at a speed of 200 r / min to obtain high-strength grouting material.
[0026] Comparative Example 1: Steps S1 and S2 in Example 1 are removed, and the rest of the implementation is the same as in Example 1.
[0027] Comparative Example 2: No humic acid was added in step S2.1 of Example 1, and the remaining steps were the same as in Example 1.
[0028] The grouting materials prepared in Examples 1-3 and Comparative Examples 1-2 were placed into molds with dimensions of 160mm × 40mm × 40mm. After normal curing for 1 day, 7 days, and 28 days, solidified grouting samples were obtained. Three parts by weight of each sample were taken and subjected to compressive strength testing using a universal testing machine. The average compressive strength was recorded. Then, the solidified grouting sample cured for 28 days was subjected to 70% of the ultimate load to obtain a pre-damaged solidified grouting sample. Three parts by weight of the pre-damaged solidified grouting sample were immersed in a 3.5% NaCl solution and allowed to self-heal for 72 hours under standard curing conditions. After the repair was completed, the residual compressive strength of the specimen was measured using an electronic universal testing machine, and the strength recovery rate was calculated.
[0029] Table 1: Compressive strength and self-healing ability of cured grout samples
[0030] As can be seen from the data of Examples 1-3 in Table 1, the grouting material prepared in this application has high strength and excellent self-healing ability in chloride ion environment. As can be seen from the data of Comparative Example 1, the self-healing microcapsule reinforcing agent prepared in this application can enhance the strength of the grouting material and make it have excellent self-healing ability. As can be seen from the data of Comparative Example 2, adding humic acid to the self-healing microcapsule wall material can enhance the strength and self-healing performance of the grouting material.
[0031] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.
Claims
1. A method for preparing a high-strength grouting material based on copper tailings, characterized in that, Includes the following steps: S1: Preparation of self-healing capsule core material Metakaolin and nano-alumina were ball-milled with anhydrous ethanol as the matrix, filtered and dried to obtain activated composite powder. The activated composite powder was mixed evenly with water glass solution, NaOH was added to adjust the pH and age it, then filtered, dried and pulverized to obtain chloride ion adsorbent. Sodium aluminate, anhydrous calcium sulfate and water were mixed evenly, NaOH solution was added to maintain the pH, stirred and then pressure filtered. The filter cake was collected, washed and pulverized to obtain expansion control agent. S2: Preparation of self-healing microcapsule enhancers Ethyl cellulose particles and humic acid are dissolved in anhydrous ethanol to obtain a microcapsule wall material solution. Magnesium oxide expansion agent, expansion control agent, sludge solidifying agent and chloride ion adsorbent are stirred and mixed evenly to obtain microcapsule mixed core material powder. The microcapsule mixed core material powder is added to a disc granulator and the microcapsule wall material solution is sprayed for granulation to obtain a self-healing microcapsule reinforcing agent. S3: Preparation of grouting material Silicate cement, sulfoaluminate cement, fly ash, calcium sulfate and calcium carbonate are dry-mixed to obtain grouting base material. River sand and copper tailings are screened to obtain screened material. Polycarboxylate superplasticizer is dissolved in deionized water to obtain superplasticizer solution. Grouting base material, screened material, superplasticizer solution, self-healing microcapsule reinforcing agent and water are mixed evenly to obtain high-strength grouting material.
2. The method for preparing a copper tailings-based high-strength grouting material according to claim 1, characterized in that, Step S1, the preparation of the self-healing capsule core material, specifically includes the following steps: S1.1: Place 45-50 parts by weight of metakaolin and 4-5 parts by weight of nano-alumina in a ball mill, add 150-180 parts by weight of anhydrous ethanol as the dispersion medium, and ball mill at 350-400 r / min for 2-3 hours to obtain a uniform slurry. Filter the uniform slurry and dry it to constant weight to obtain activated composite powder. Mix the activated composite powder with 30-35 parts by weight of water glass solution with a modulus of 3.2-3.5, stir at 500-650 r / min for 10-15 minutes at room temperature, then add NaOH to adjust the pH to 14, age for 10-12 hours, filter, place the filter cake in a vacuum drying oven to dry to constant weight, pulverize and pass through a 600-625 mesh sieve to obtain chloride ion adsorbent; S1.2: Add 200-250 parts by weight of water to a container, heat to 40-45℃ and keep warm, then add 25-30 parts by weight of sodium aluminate and 35-40 parts by weight of anhydrous calcium sulfate, stir at 400-450 r / min for 15-20 minutes, then add 10% NaOH solution to maintain pH at 11-12, and continue stirring for 3-4 hours to obtain the swelling control agent solution; S1.3: Transfer the swelling control agent solution to a plate and frame filter press for filtration. Collect the filter cake, wash it with clean water 3-4 times, dry it, and then pulverize it to a particle size of 10-50μm to obtain the swelling control agent.
3. The method for preparing a copper tailings-based high-strength grouting material according to claim 2, characterized in that, Step S2, the preparation of the self-healing microcapsule enhancer, specifically includes the following steps: S2.1: Place ethyl cellulose particles, humic acid and anhydrous ethanol in a container and stir at a stirring speed of 800-1000 r / min until the solids are completely dissolved to obtain a microcapsule wall material solution. S2.2: Place 65-70 parts by weight of magnesium oxide expanding agent, 35-40 parts by weight of expansion control agent, 40-45 parts by weight of sludge solidifying agent and chloride ion adsorbent in a mixer and stir at a stirring speed of 400-600 r / min until the mixture presents a uniform color to obtain microcapsule mixed core material powder. S2.3: Pour the microcapsule mixed core material powder into a disc granulator, set the rotation speed of the disc granulator to 65-75 r / min and the tilt angle to 45-50°, and continuously spray the microcapsule wall material solution onto the surface of the microcapsule mixed core material powder during the rotation process. The spraying speed is 0.1-0.3 L / min, and the total amount of microcapsule wall material solution sprayed is 45-50% of the microcapsule mixed core material powder, thus obtaining a self-healing microcapsule reinforcing agent.
4. The method for preparing a copper tailings-based high-strength grouting material according to claim 3, characterized in that, Step S3 involves preparing the grouting material, specifically including the following steps: S3.1: Add 600-650 parts by weight of 52.5 grade silicate cement, 120-150 parts by weight of sulfoaluminate cement, 50-60 parts by weight of fly ash, 25-30 parts by weight of calcium sulfate and 25-30 parts by weight of calcium carbonate into a mixer and dry mix at a speed of 45-50 r / min for 12-15 minutes to obtain grouting base material; S3.2: Place 400-450 parts by weight of river sand and 60-80 parts by weight of copper tailings in a screening machine with an aperture of 4-6 mm and vibrate and screen for 5-7 minutes to obtain the screened material. Dissolve 2.5-3 parts by weight of polycarboxylate superplasticizer in 10-15 parts by weight of deionized water to obtain a superplasticizer solution. S3.3: Place the grouting base material obtained in step S3.1 and the sieved material obtained in step S3.2 into a mixer and dry mix for 3-5 minutes. Then add the water-reducing agent solution prepared in step S3.2, 2-3% of the total mass of the grouting base material, the self-healing microcapsule reinforcing agent, and 300-350 parts by weight of water. Stir evenly at a speed of 180-200 r / min to obtain high-strength grouting material.
5. The method for preparing a copper tailings-based high-strength grouting material according to claim 3, characterized in that, In step S2.1, the concentration of ethyl cellulose in the microcapsule wall material solution is 50-60 g / L, and the concentration of humic acid is 1-2 g / L.
6. The method for preparing a copper tailings-based high-strength grouting material according to claim 3, characterized in that, The preparation method of the sludge solidifying agent in step S2.2 is as follows: it is prepared by thoroughly mixing 4-8 parts of sodium polyacrylate, 1-2 parts of polyacrylamide, 0.5-1 parts of polycarboxylate superplasticizer, 2-5 parts of water glass, 3-8 parts of silicate cement, 5-10 parts of fly ash, 18-28 parts of ferrous sulfate, and 15-25 parts of zeolite.
7. The method for preparing a copper tailings-based high-strength grouting material according to claim 4, characterized in that, In step S3.2, the fineness modulus of the river sand is 2.3-2.
6.
8. The method for preparing a copper tailings-based high-strength grouting material according to claim 4, characterized in that, In step 3.2, the apparent density of copper tailings is 2700-2900 kg / m³. 3 The stone powder has a mass fraction of 12.5-14% and a fineness modulus of 0.8-0.
9.
9. A high-strength grouting material based on copper tailings, characterized in that, It is prepared by any one of the preparation methods of copper tailings-based high-strength grouting material according to claims 1-8.