Industrial solid waste high-strength concrete and preparation method thereof

Abstract

The invention relates to the technical field of special low-carbon building materials, in particular to industrial solid waste high-strength concrete and a preparation method thereof, and aims to solve the problem that existing photocatalytic concrete cannot effectively guarantee photocatalytic performance and mechanical properties at the same time. The concrete matrix is prepared from the following raw materials in parts by weight: 550 to 650 parts of cement, 300 to 400 parts of composite admixture, 600 to 700 parts of aggregate, 25 to 35 parts of water reducing agent, 165 to 185 parts of water and 8 to 12 parts of modified copper-plated steel fiber; 1-3 parts of conductive fibers; the composite admixture is composed of fly ash, silica fume and catalyst-loaded yellow phosphorus slag micro-powder according to a mass ratio of (3-4): (2-3): (1-2); the modified copper-plated steel fibers comprise copper-plated steel fibers of which the surfaces are coated with conductive polymers; the surface functional film is a hydrophobic photocatalytic composite film formed by in-situ reaction of a silicon-based penetrant on the surface of the concrete. The composite admixture, the modified copper-plated steel fiber, the conductive fiber and the surface functional film act together in a system, so that the photocatalytic purification performance and the structural mechanical property are synchronously optimized.

Description

Technical Field

[0001] This invention relates to the field of special low-carbon building materials technology, and in particular to a high-strength concrete made from industrial solid waste and its preparation method. Background Technology

[0002] Photocatalytic concrete has attracted much attention due to its ability to degrade air pollutants. Current technologies primarily achieve photocatalytic functionality by incorporating photocatalysts such as nano-titanium dioxide into the concrete or coating it onto its surface. However, these methods still have several significant drawbacks: firstly, in internally incorporated photocatalytic concrete, the photocatalyst is encapsulated within the cement matrix, resulting in insufficient contact with pollutant gases, and the easy recombination of photogenerated electron-hole pairs leads to low catalytic efficiency; secondly, externally coated photocatalytic coatings have weak interfacial adhesion to the concrete matrix, making them prone to peeling under service conditions such as temperature and humidity changes and freeze-thaw cycles, resulting in poor functional durability.

[0003] To improve photocatalytic efficiency, some studies have attempted to introduce conductive components, such as carbon fibers and graphene, into concrete to construct rapid charge transfer channels and suppress electron-hole recombination. However, these conductive materials often have poor compatibility with the cement matrix, are prone to agglomeration and uneven distribution, and their incorporation often leads to decreased concrete workability, impaired mechanical properties, and even introduces durability risks. Furthermore, existing conductive reinforcing materials have limited functionality and cannot simultaneously meet the synergistic requirements of structural reinforcement, charge conduction, and long-term durability.

[0004] In terms of concrete reinforcing fibers, while traditional steel fibers can significantly improve the toughness and crack resistance of concrete, their surfaces are prone to corrosion and have weak interfacial bonding with the cement matrix, leading to long-term performance degradation. Although some studies have modified the fiber surface by copper plating or polymer coating to improve its durability or impart certain functions, these modified layers often do not bond firmly to the fiber matrix and are prone to peeling and failure under the complex stress and chemical environment of concrete. Furthermore, the modification process is cumbersome and it is difficult to achieve both multifunctional integration and stability.

[0005] Therefore, developing a novel composite material system that can efficiently improve the photocatalytic performance of concrete, simultaneously enhance its mechanical properties and durability, and exhibit synergistic effects among its functional components has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] This invention provides a novel composite material system that efficiently improves the photocatalytic performance of concrete, simultaneously enhances its mechanical properties and durability, and exhibits synergistic effects among its functional components.

[0007] To alleviate the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0008] A high-strength concrete for industrial solid waste includes a concrete matrix and a surface functional membrane;

[0009] The concrete matrix comprises the following raw materials in parts by weight: 550-650 parts cement, 300-400 parts composite admixture, 600-700 parts aggregate, 25-35 parts water-reducing agent, 165-185 parts water, 8-12 parts modified copper-plated steel fiber, and 1-3 parts conductive fiber.

[0010] The composite admixture is composed of fly ash, silica fume and catalyst-supported yellow phosphorus slag powder in a mass ratio of (3-4):(2-3):(1-2);

[0011] The modified copper-plated steel fiber includes copper-plated steel fiber with a conductive polymer coated on its surface.

[0012] The conductive fiber is selected from carbon fiber or copper fiber;

[0013] The surface functional membrane is a hydrophobic photocatalytic composite membrane formed by in-situ reaction of a silicon-based penetrant on the concrete surface.

[0014] Furthermore,

[0015] The preparation method of the composite admixture is as follows:

[0016] (1) Grind the yellow phosphorus slag into balls with a specific surface area ≥750m² / kg and D50 ≤8μm;

[0017] (2) Tetrabutyl titanate was dissolved in ethanol to obtain a homogeneous organic titanium source solution; cerium ammonium nitrate was dissolved in deionized water to obtain an inorganic cerium source solution; the cerium salt aqueous solution was slowly added dropwise to the stirred titanium alkoxide alcohol solution, wherein the molar ratio of titanium to cerium was (3:1)-(1:1).

[0018] (3) The micro powder from step (1) is immersed in the solution from step (2) using vacuum-assisted immersion for 2-4 hours; the solid-liquid ratio is 1:8-12.

[0019] (4) After taking it out, dry it at 80-100℃ and then calcine it at 450-550℃ for 2-3 hours to obtain the catalyst micro powder supported on TiO2-CeO2 heterojunction.

[0020] Furthermore,

[0021] The method for preparing the modified copper-plated steel fiber is as follows:

[0022] (1) The copper-plated steel fibers are subjected to alkaline washing and degreasing, acid washing and activation, and silane coupling agent treatment in sequence. The amount of silane coupling agent added is 1%-3% of the mass of aniline monomer;

[0023] (2) Disperse the pretreated fibers in an aqueous solution of ammonium persulfate, with a molar ratio of ammonium persulfate to aniline monomer of 1:1. Prepare an aqueous solution of ammonium persulfate with a concentration of 0.5–1.0 mol / L and react for 12–24 hours.

[0024] (3) The fiber that has completed the polymerization reaction and is coated with intrinsic polyaniline is immersed in a 0.5-1.0 mol / L p-toluenesulfonic acid solution for 2-3 hours under nitrogen protection, with a heating rate of 2℃ / min and a holding time of 60 minutes.

[0025] Furthermore,

[0026] The copper-plated steel fiber has a diameter of 0.18-0.22 mm, a length of 12-16 mm, and a copper plating thickness of 1-3 μm.

[0027] Furthermore,

[0028] The permeate is composed of the following raw materials in parts by weight: 15-25 parts alkylalkoxysilane; 10-15 parts nano-SiO2 sol; 2-5 parts tetrabutyl titanate; 55-65 parts ethanol; and 0.5-1 parts catalyst.

[0029] The alkylalkoxysilane, tetrabutyl titanate, and a portion of the ethanol are mixed and stirred until homogeneous to obtain solution A; the nano-SiO2 sol, catalyst, and the remaining ethanol are mixed and stirred until homogeneous to obtain solution B; under stirring conditions, solution B is slowly added to solution A, and after homogeneous mixing, the permeate is obtained.

[0030] Furthermore,

[0031] The thickness of the surface functional film is 0.1-0.3 mm.

[0032] Furthermore,

[0033] The cement is silicate cement or ordinary silicate cement.

[0034] Furthermore,

[0035] The aggregate is quartz sand with a maximum particle size of no more than 2.36 mm and a fineness modulus of 2.3-2.8.

[0036] Furthermore,

[0037] The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0038] A method for preparing high-strength concrete from industrial solid waste, as described above, includes the following steps:

[0039] (1) Raw material preparation: Prepare catalyst-supported yellow phosphorus slag micro powder and modified copper-plated steel fiber;

[0040] (2) Batching and mixing: Weigh cement, composite admixture and quartz sand according to the proportion, and dry mix; add water and water-reducing agent, and stir to form a uniform slurry; slowly add modified copper-plated steel fiber, and continue stirring until the fiber is evenly dispersed;

[0041] (3) Pouring and curing: Pour the mixture into a mold coated with release agent, vibrate to compact, cover with plastic film, and cure and demold; continue standard curing for 7-14 days after demolding;

[0042] (4) Surface treatment: Clean the concrete surface, apply penetrating liquid, and cure it. Avoid direct contact with water during the process.

[0043] (5) Finished product curing: After the surface functional film is formed, continue standard curing for 28 days or the required age.

[0044] The beneficial effects of the high-strength concrete made from industrial solid waste in this invention are analyzed as follows:

[0045] The composite admixture uses yellow phosphorus slag powder as a carrier to support TiO2-CeO2 heterojunctions via a sol-gel method. TiO2, as a wide-bandgap semiconductor, exhibits catalytic activity in the ultraviolet region; the introduction of CeO2, due to its variable Ce³⁺ / CeO2 ratio... 4 The ⁺ valence state not only broadens the photoresponse to the visible light region but also acts as a highly efficient electron scavenger, promoting the initial separation of photogenerated electron-hole pairs. More importantly, the activated yellow phosphorus slag powder possesses a porous structure and abundant surface groups, enabling it to specifically adsorb and pre-enrich gaseous pollutants (such as NOx and SO2), overcoming the key bottleneck of reactant mass transfer limitations in gas-solid phase reactions. Furthermore, these ultrafine powders, in synergy with fly ash and silica fume, fully leverage the physical filling effect, refine the pore size of cement paste, and optimize the microstructure of concrete.

[0046] Modified copper-plated steel fibers offer several advantages. First, the copper-plated fiber core acts as a high-strength, toughening phase, effectively bridging cracks and dissipating energy during concrete cracking, significantly improving the material's fracture toughness and impact resistance. Second, through in-situ polymerization and acid doping, a highly conductive polyaniline shell is coated onto its surface. This conductive polymer shell forms a strong chemical and physical interface with the cement hydration products, greatly increasing the fiber's pull-out work and combining macroscopic reinforcement with interfacial strengthening. Simultaneously, this conductive shell makes the fiber itself a micro-conductive node within the concrete, providing a pathway for charge transport.

[0047] When the TiO2-CeO2 heterojunction loaded on the composite admixture is excited by light to generate electron-hole pairs, the separated electrons need to be rapidly removed to prevent recombination. At this time, the conductive shell of the modified copper-plated steel fiber and the specially added conductive fibers (such as carbon fiber) together construct a three-dimensional interconnected conductive network inside the concrete. This network can rapidly collect and migrate the photogenerated electrons generated by each catalytic active site, greatly suppressing charge recombination and enabling the photocatalytic reaction to proceed efficiently and stably even under weak light conditions.

[0048] The surface functional membrane, through silane infiltration crystallization technology, chemically reacts with the concrete matrix to form a chemically bonded, integrated gradient reinforcement layer. This membrane provides excellent hydrophobicity, actively blocking the intrusion of external moisture, chloride ions, and other corrosive media. Simultaneously, the high density achieved internally through the addition of composite admixtures and fibers enhances its impermeability from within.

[0049] In summary, this invention achieves simultaneous optimization of photocatalytic purification performance and structural mechanical properties by having composite admixtures, modified copper-plated steel fibers, conductive fibers, and surface functional films work together in the system. Detailed Implementation

[0050] Example 1

[0051] The preparation of a high-strength concrete for industrial solid waste, the raw material components and weight parts are as follows: 600 parts of silicate cement, 350 parts of composite admixture, 650 parts of quartz sand (fineness modulus 2.5, maximum particle size 2.36mm), 30 parts of polycarboxylate superplasticizer, 175 parts of water, 10 parts of modified copper-plated steel fiber, and 2 parts of carbon fiber.

[0052] The preparation method of the composite admixture is as follows: Yellow phosphorus slag is ball-milled to a specific surface area of ​​780 m² / kg and a D50 of 7.2 μm. Then, tetrabutyl titanate is dissolved in ethanol to obtain an organic titanium source solution; cerium ammonium nitrate is dissolved in deionized water to obtain an inorganic cerium source solution; a cerium salt aqueous solution is slowly added dropwise to a vigorously stirred titanium alkoxide alcohol solution, controlling the molar ratio of titanium to cerium to be 2:1, to obtain a uniform precursor sol. The above-mentioned yellow phosphorus slag micropowder is impregnated in the precursor sol at a solid-liquid ratio of 1:10 under vacuum for 3 hours. After removal, it is dried at 90℃ and then calcined at 500℃ for 2.5 hours to obtain a catalyst micropowder supported on a TiO₂-CeO₂ heterojunction. Finally, the catalyst micropowder is mixed uniformly with fly ash and silica fume at a mass ratio of 3.5:2.5:1.5 to obtain the composite admixture.

[0053] The modified copper-plated steel fiber was prepared as follows: Copper-plated steel fibers with a diameter of 0.20 mm, a length of 14 mm, and a copper plating thickness of 2 μm were taken and subjected to alkali washing and degreasing, acid washing and activation, and then treated with a silane coupling agent accounting for 2% of the aniline monomer mass. The treated fibers were dispersed in a 0.8 mol / L ammonium persulfate aqueous solution, wherein the molar ratio of ammonium persulfate to aniline monomer was 1:1, and reacted at room temperature for 18 hours. After the reaction, the polyaniline-coated fibers were immersed in a 0.8 M p-toluenesulfonic acid solution for 2 hours under nitrogen protection, and then the temperature was increased to 190℃ at a rate of 2℃ / min and held for 60 minutes. Finally, after separation, washing, and drying at 70℃, modified copper-plated steel fibers with conductive polyaniline coated on the surface were obtained.

[0054] The preparation method of the surface functional membrane permeate is as follows: Weigh out 20 parts by weight of octadecyltriethoxysilane, 12 parts by weight of nano-SiO2 sol, 3.5 parts by weight of tetrabutyl titanate, 61.5 parts by weight of ethanol, and 0.8 parts by weight of dibutyltin dilaurate catalyst. First, mix octadecyltriethoxysilane, tetrabutyl titanate, and a portion of ethanol, and stir until homogeneous to obtain solution A; then mix nano-SiO2 sol, catalyst, and the remaining ethanol, and stir until homogeneous to obtain solution B; under continuous stirring, slowly add solution B to solution A, and after mixing until homogeneous, the permeate is obtained.

[0055] The concrete preparation was carried out according to the following steps: Cement, composite admixtures, and quartz sand were weighed according to the mix proportions and dry-mixed evenly. Water and water-reducing agent were added, and mechanically stirred for 3 minutes to form a homogeneous paste. Modified copper-plated steel fibers and carbon fibers were slowly added, and stirring was continued for 5 minutes until the fibers were evenly dispersed. The mixture was poured into a mold coated with a release agent, vibrated to compact it, covered with a plastic film, and cured at 20±2℃ and relative humidity ≥95% for 24 hours before demolding. After demolding, the specimens continued standard curing for 14 days. After cleaning the surface, the aforementioned penetrating liquid was applied, with the coating amount controlled at 300 g / m². The specimens were then placed in an environment of 25℃ and relative humidity 60% for 7 days of reaction curing, avoiding direct contact with water during this period. After the surface functional film formed, the specimens continued standard curing for 28 days.

[0056] The prepared concrete specimens were subjected to performance tests. Their 28-day compressive strength was 72.5 MPa, flexural strength was 8.6 MPa, and fracture energy reached 2800 J / m². According to the standard "Test Method for Air Purification Performance of Photocatalytic Materials and Products", under simulated sunlight (1000 Lux) irradiation, the NOx degradation efficiency was 85% after 4 hours.

[0057] Example 2

[0058] This embodiment provides a high-strength concrete for industrial solid waste, the formula of which is adjusted based on Example 1. The specific raw materials by weight are: 580 parts of silicate cement, 380 parts of composite admixture, 630 parts of quartz sand (fineness modulus 2.5, maximum particle size 2.36mm), 28 parts of polycarboxylate superplasticizer, 170 parts of water, 9 parts of modified copper-plated steel fiber, and 1.5 parts of copper fiber (5mm in length).

[0059] In the composite admixture, the mass ratio of catalyst powder to fly ash and silica fume is 3:3:2. The modified copper-plated steel fibers used have a diameter of 0.18 mm and a length of 16 mm. The alkylsilane content in the permeate is adjusted to 22 parts, and the nano-SiO2 sol content is 13 parts. The specifications of other raw materials, preparation processes, and parameters are the same as in Example 1.

[0060] The prepared concrete specimens were subjected to performance tests. Their 28-day compressive strength was 70.8 MPa, flexural strength was 8.2 MPa, and fracture energy was 2650 J / m². Under the same photocatalytic testing conditions, the 4-hour degradation efficiency of NOx was 82%.

[0061] Comparative Example 1

[0062] Compared to Example 1, this comparative example did not use composite admixtures; instead, it used unmodified ordinary fly ash and silica fume in equal amounts to replace the composite admixtures, maintaining a total weight of 350 parts. The remaining raw material components, dosages, and preparation methods were identical to those in Example 1. Performance test results are as follows: 28-day compressive strength was 65.4 MPa, and flexural strength was 7.1 MPa. Photocatalytic testing showed that the 4-hour NOx degradation efficiency was only 42%.

[0063] Comparative Example 2

[0064] Compared to Example 1, this comparative example did not use modified copper-plated steel fiber, meaning the fiber was not added, and only 2 parts of carbon fiber (carbon fiber) were retained in the concrete matrix. The remaining raw material components, amounts, and preparation methods were exactly the same as in Example 1. Performance test results are as follows: 28-day compressive strength was 63.2 MPa, flexural strength was 6.8 MPa, and the breaking energy was significantly reduced to 1850 J / m². Photocatalytic testing showed a 4-hour NOx degradation efficiency of 68%.

[0065] Comparative Example 3

[0066] Compared to Example 1, this comparative example did not include carbon fiber. The concrete matrix contained only 10 parts of modified copper-plated steel fiber. The remaining raw material components, amounts, and preparation methods were exactly the same as in Example 1. Performance test results are as follows: the 28-day compressive strength was 71.0 MPa, and the flexural strength was 8.5 MPa, with mechanical properties similar to those of Example 1. However, photocatalytic testing showed that the 4-hour NOx degradation efficiency decreased to 58%.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-strength concrete made from industrial solid waste, characterized in that, Including the concrete substrate and surface functional membrane; The concrete matrix comprises the following raw materials in parts by weight: 550-650 parts cement, 300-400 parts composite admixture, 600-700 parts aggregate, 25-35 parts water-reducing agent, 165-185 parts water, 8-12 parts modified copper-plated steel fiber, and 1-3 parts conductive fiber. The composite admixture is composed of fly ash, silica fume and catalyst-supported yellow phosphorus slag powder in a mass ratio of (3-4):(2-3):(1-2); The modified copper-plated steel fiber includes copper-plated steel fiber with a conductive polymer coated on its surface. The conductive fiber is selected from carbon fiber or copper fiber; The surface functional membrane is a hydrophobic photocatalytic composite membrane formed by in-situ reaction of a silicon-based penetrant on the concrete surface.

2. The high-strength industrial solid waste concrete according to claim 1, characterized in that, The preparation method of the composite admixture is as follows: (1) Grind the yellow phosphorus slag into balls with a specific surface area ≥750m² / kg and D50 ≤8μm; (2) Tetrabutyl titanate was dissolved in ethanol to obtain a homogeneous organic titanium source solution; cerium ammonium nitrate was dissolved in deionized water to obtain an inorganic cerium source solution; the cerium salt aqueous solution was slowly added dropwise to the stirred titanium alkoxide alcohol solution, wherein the molar ratio of titanium to cerium was (3:1)-(1:1). (3) The micro powder from step (1) is immersed in the solution from step (2) using vacuum-assisted immersion for 2-4 hours; the solid-liquid ratio is 1:8-12. (4) After taking it out, dry it at 80-100℃ and then calcine it at 450-550℃ for 2-3 hours to obtain the catalyst micro powder supported on TiO2-CeO2 heterojunction.

3. The high-strength industrial solid waste concrete according to claim 2, characterized in that, The method for preparing the modified copper-plated steel fiber is as follows: (1) The copper-plated steel fibers are subjected to alkaline washing and degreasing, acid washing and activation, and silane coupling agent treatment in sequence. The amount of silane coupling agent added is 1%-3% of the mass of aniline monomer; (2) Disperse the pretreated fibers in an aqueous solution of ammonium persulfate, with a molar ratio of ammonium persulfate to aniline monomer of 1:

1. Prepare an aqueous solution of ammonium persulfate with a concentration of 0.5–1.0 mol / L and react for 12–24 hours. (3) The fiber that has completed the polymerization reaction and is coated with intrinsic polyaniline is immersed in a 0.5-1.0 mol / L p-toluenesulfonic acid solution for 2-3 hours under nitrogen protection, with a heating rate of 2℃ / min and a holding time of 60 minutes.

4. The high-strength industrial solid waste concrete according to claim 3, characterized in that, The copper-plated steel fiber has a diameter of 0.18-0.22 mm, a length of 12-16 mm, and a copper plating thickness of 1-3 μm.

5. The high-strength industrial solid waste concrete according to claim 4, characterized in that, The permeate is composed of the following raw materials in parts by weight: 15-25 parts alkylalkoxysilane; 10-15 parts nano-SiO2 sol; 2-5 parts tetrabutyl titanate; 55-65 parts ethanol; and 0.5-1 part catalyst. The alkylalkoxysilane, tetrabutyl titanate, and a portion of the ethanol are mixed and stirred until homogeneous to obtain solution A; the nano-SiO2 sol, catalyst, and the remaining ethanol are mixed and stirred until homogeneous to obtain solution B; under stirring conditions, solution B is slowly added to solution A, and after homogeneous mixing, the permeate is obtained.

6. The high-strength industrial solid waste concrete according to claim 5, characterized in that, The thickness of the surface functional film is 0.1-0.3 mm.

7. The high-strength industrial solid waste concrete according to claim 6, characterized in that, The cement is silicate cement or ordinary silicate cement.

8. The high-strength concrete for industrial solid waste according to claim 7, characterized in that, The aggregate is quartz sand with a maximum particle size of no more than 2.36 mm and a fineness modulus of 2.3-2.

8.

9. The high-strength industrial solid waste concrete according to claim 8, characterized in that, The water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

10. A method for preparing high-strength concrete from industrial solid waste as described in any one of claims 1-9, characterized in that, Includes the following steps: (1) Raw material preparation: Prepare catalyst-supported yellow phosphorus slag micro powder and modified copper-plated steel fiber; (2) Batching and mixing: Weigh cement, composite admixture and quartz sand according to the proportion, and dry mix; add water and water-reducing agent, and stir to form a uniform slurry; slowly add modified copper-plated steel fiber, and continue stirring until the fiber is evenly dispersed; (3) Pouring and curing: Pour the mixture into a mold coated with release agent, vibrate to compact, cover with plastic film, and cure and demold; continue standard curing for 7-14 days after demolding; (4) Surface treatment: Clean the concrete surface, apply penetrating liquid, and cure it, avoiding direct contact with water during the process; (5) Finished product curing: After the surface functional film is formed, continue standard curing for 28 days or the required age.