Modified gold tailing-based small prefabricated part for highway engineering and preparation method of modified gold tailing-based small prefabricated part

Abstract

The invention relates to the technical field of highway engineering materials, in particular to a small prefabricated part for highway engineering based on modified gold tailings and a preparation method of the small prefabricated part. Through modification treatment of the gold tailings, pores in the prefabricated part are further reduced, the freezing resistance and the salt corrosion resistance are remarkably improved while high strength is formed, and the method is suitable for preparing small prefabricated parts for highway engineering in cold regions or coastal regions.

Description

Technical Field

[0001] The present invention relates to the technical field of highway engineering materials, and particularly relates to a small precast member for highway engineering based on modified gold tailings and a preparation method thereof. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or any form of implication that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] In highway engineering, small precast members (such as curb stones, side ditch covers, slope protection blocks, isolation piers, marking blocks, etc.) mostly use ordinary C30 concrete. Ordinary C30 concrete has low cost and mature technology. However, it has problems such as easy cracking and poor salt frost resistance. Especially in cold regions or coastal saline environments, members based on ordinary concrete often suffer from surface peeling, chipping of edges and corners, and even structural failure due to salt ion erosion and freeze-thaw cycles, requiring frequent maintenance, which significantly increases the project cost. At the same time, traditional concrete materials rely on cement and crushed stones, and a large amount of natural resources need to be mined, which intensifies the pressure on the ecological environment.

[0004] At present, there are mainly two measures to improve the salt frost resistance of concrete: one is the external isolation method, that is, spraying or impregnating sealing materials such as water glass. This method can effectively block open pores, reduce the chloride ion penetration rate, and improve the salt frost resistance, but the preparation process is complicated and the cost increases; the other is the internal pore structure adjustment method, that is, adding ultra-fine powder in the concrete composition materials to fill capillary pores or introducing air bubbles to block capillary pores; however, common ultra-fine powders are silica fume, graphene, etc., which are expensive and greatly increase the preparation cost; the air bubble introduction method can block the connectivity of capillary pores and reduce the water absorption rate, but it has an adverse effect on the material strength.

[0005] At the same time, gold tailings are solid wastes discharged after gold ore is beneficiated or gold is recovered by gold extraction technology. Gold tailings can be applied to prepare engineering materials due to their characteristics such as fine particle size, high specific surface area, and rich silicon-aluminum components. However, if gold tailings are directly applied to precast members for highway engineering, problems such as increased water demand and rising porosity will occur due to their fine particle size, and thus the salt frost resistance cannot be improved. Summary of the Invention

[0006] In order to overcome the above problems, the present invention provides a small precast member for highway engineering based on modified gold tailings and a preparation method thereof. In the present invention, through the modification treatment of gold tailings, the pores inside the precast member are further reduced. While forming a relatively high strength, the frost resistance and salt erosion resistance are significantly improved, which is suitable for preparing small precast members for highway engineering in cold regions or coastal regions.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect of the present invention, there is provided a small precast member for highway engineering based on modified gold tailings. The raw materials include, by weight: 52 - 64 parts of modified gold tailings, 5 - 9 parts of activator, 26 - 32 parts of active mineral admixture, 8 - 15 parts of epoxy resin, 0.5 - 2 parts of water reducing agent, 0.5 - 1 part of expansive agent, 0.5 - 1 part of air entraining agent, 0.1 - 0.5 part of fiber, and 10 - 20 parts of water; The preparation method of the modified gold tailings includes the following steps: Add diethylene glycol butyl ether acetate, hexakis(ethylphosphite)triamine, and nano - montmorillonite to the calcium nitrite aqueous solution in sequence, and obtain a modified solution after mixing evenly; Soak the gold tailings in the modified solution, stir, take them out and dry and cure to obtain modified gold tailings; The mass ratio of calcium nitrite, nano - montmorillonite, diethylene glycol butyl ether acetate, and hexakis(ethylphosphite)triamine is (1 - 3):(5 - 10):(2 - 4):(1 - 2).

[0008] Within the limited mass ratio range, calcium nitrite, nano - montmorillonite, diethylene glycol butyl ether acetate, and hexakis(ethylphosphite)triamine have the optimal modification effect on gold tailings.

[0009] In one or more embodiments, the concentration (mass percentage) of the calcium nitrite aqueous solution is 28 - 40%, preferably 30%. The calcium nitrite aqueous solution is alkaline, and the alkaline environment promotes the dispersion of montmorillonite and the adsorption of Ca 2+ , forming a dense coating layer, reducing the porosity of gold tailings. At the same time, calcium nitrite has strong oxidizing properties, which can form a passivation film on the surface of gold tailings, inhibit the oxidation reaction of metal ions, and form a stable composite oxide to form a physical barrier.

[0010] In one or more embodiments, the soaking time of the gold tailings in the modified solution is 20 - 30 min. Within this limited time, various modifiers can fully react with the gold tailings to obtain modified gold tailings.

[0011] In one or more embodiments, the particle size of the gold tailings is 75 - 600 μm. If the particle size of the gold tailings is too fine, it will cause excessive water demand for concrete, the mixture is viscous, and it is not easy to form small precast members. On the contrary, if the particle size is too large, it will increase the contact area between the cementitious material and the gold tailings particles, and pores are likely to be generated on the contact surface, increasing the probability of ion erosion.

[0012] In one or more embodiments, the average crystal wafer thickness of the nano - montmorillonite is less than 25 nm, and the montmorillonite content is greater than 95%.

[0013] In one or more embodiments, the activator is composed of red mud, industrial by-product gypsum, and carbide slag, and the mass ratio of red mud, industrial by-product gypsum, and carbide slag is (10~15):(5~10):(2~5). Red mud and carbide slag are strongly alkaline and jointly construct an alkaline environment with industrial by-product gypsum. In this environment, the stable silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron network structures in the active admixture are destroyed by alkaline ions (such as OH - ), depolymerized, and release active elements such as silicon and aluminum.

[0014] Preferably, the red mud is Bayer red mud with a pH value of 7~8.5; Preferably, the industrial by-product gypsum is fluorogypsum with a CaSO4 content of not less than 85%; Preferably, the content of Ca(OH)2 in carbide slag is greater than 85%.

[0015] In one or more embodiments, the active mineral admixture is composed of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micropowder, and incineration fly ash; the mass ratio of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micropowder, and incineration fly ash is (40~55):(15~20):(1~3):(5~10):(3~8):(5~10):(10~15).

[0016] Preferably, the blast furnace slag is above S70 grade, and the content of SiO2+CaO is greater than 70%; Preferably, the coal gangue powder is decarbonized coal gangue powder after microbial mineralization treatment; Preferably, the particle size of the silica fume is less than 1 μm, and the SiO2 content is greater than 80%; Preferably, the content of SiO2+CaO+Al2O3 in the steel slag powder is greater than 60%; Preferably, the content of SiO2+CaO+Al2O3 in the metakaolin is greater than 65%; Preferably, the content of SiO2+CaO+Al2O3 in the recycled aggregate micropowder is greater than 50%; Preferably, the content of SiO2+CaO+Al2O3 in the incineration fly ash is greater than 70%.

[0017] The content of SiO2+CaO+Al2O3 in the steel slag powder, metakaolin, recycled aggregate micropowder, and incineration fly ash in the active mineral admixture is limited here to ensure that these solid waste raw materials have a sufficient total amount of active oxides to support their basic cementitious activity and strength development potential. At the same time, the content of impurities and inert components is indirectly controlled to ensure the stability of the hydration reaction, the consistency of material properties, and the mechanical and durability properties of the final product, and to achieve the efficient and safe utilization of solid waste resources.

[0018] In one or more embodiments, the epoxy resin is a waterborne epoxy resin with a solid content of 99% and an epoxy equivalent of 190 - 220 g / eq. By defining a high solid content, the film-forming property during construction and environmental friendliness can be ensured (reducing shrinkage cracking and lowering VOC), while precisely controlling the epoxy equivalent to optimize the crosslinking density and reaction activity, ensuring the formation of a stable three-dimensional network structure with high strength and chemical corrosion resistance after curing, and ultimately achieving a synergistic improvement in material properties, construction reliability, and environmental benefits.

[0019] In one or more embodiments, the water reducer is a polycarboxylate-based water reducer with a water reduction rate greater than 40%. Through its efficient dispersion effect, the water-binder ratio is significantly reduced (a water reduction effect of >40%), simultaneously achieving a triple jump in concrete performance - optimizing fluidity to ensure construction workability, driving the improvement of strength and density with a low water-binder ratio, and saving cementitious materials to reduce carbon emissions. Ultimately, it supports the coordinated development of the strength, durability, and low-carbonization of high-performance concrete with ultra-high water reduction efficiency.

[0020] Preferably, the polycarboxylate-based water reducer is specifically selected from one of the PCA®-I series and the PCA®-9 series.

[0021] In one or more embodiments, the expansive agent is a calcium sulfoaluminate-based expansive agent.

[0022] Preferably, the calcium sulfoaluminate-based expansive agent is the UEA-1 expansive agent.

[0023] In one or more embodiments, the air-entraining agent is an alkylbenzene sulfonate-based air-entraining agent.

[0024] Preferably, the alkylbenzene sulfonate-based air-entraining agent is selected from one of sodium dodecylbenzene sulfonate and sodium dodecyl sulfate.

[0025] In one or more embodiments, the fibers include nanoscale fibers and millimeter-scale fibers, and the mass ratio of the nanoscale fibers to the millimeter-scale fibers is (1 - 2) : (5 - 7). The nanoscale fibers can fill the tiny pores inside the concrete and enhance the compactness of the material, while the millimeter-scale fibers can provide reinforcement effects in a larger range. The combination of the two can comprehensively improve the overall performance of the concrete at different scales, and the multi-scale fibers reduce shrinkage cracking during the curing process.

[0026] Preferably, the nanoscale fiber is one of carbon nanotube fibers and graphene fibers, with a particle size of 10 - 30 nm; Preferably, the millimeter-scale fiber is one of polyethylene fibers, polypropylene fibers, and steel fibers, with a particle size of 2 - 4 mm.

[0027] The second aspect of the present invention provides a preparation method of small precast components for highway engineering based on modified gold tailings in the first aspect, comprising the following steps: (1) Mix the activator and the active mineral admixture and then carry out ball milling to obtain a powder mixture; (2) Uniformly mix the modified gold tailings, the powder mixture, the expansive agent, the air-entraining agent and the fiber to obtain a solid mixture; (3) Add all the water, epoxy resin and water reducer to the solid mixture and mix uniformly to obtain a slurry of small precast components for highway engineering based on modified gold tailings; (4) Pour the slurry of small precast components for highway engineering based on modified gold tailings into a mold to obtain small precast components for highway engineering based on modified gold tailings.

[0028] In one or more embodiments, in step (1), during the ball milling process, the ball-to-material ratio is (2:1) to (5:1), the ball milling time is 2 to 3 min, and the rotation speed is 400 to 500 r / min. Under such ball milling conditions, it can ensure that the specific surface area of the powder mixture after grinding is 350 to 450 kg / m 2 , while reducing energy consumption and metal consumption.

[0029] The beneficial effects of the present invention are as follows: (1) The present invention provides a small precast component for highway engineering based on modified gold tailings and a preparation method thereof. In the present invention, through the modification treatment of gold tailings, the pores inside the precast components are further reduced. While forming a relatively high strength, the frost resistance and salt erosion resistance are significantly improved, which is suitable for preparing small precast components for highway engineering in cold regions or coastal regions. Specifically, the calcium nitrite aqueous solution is alkaline, and the alkaline environment promotes the dispersion of montmorillonite and the adsorption of Ca 2+ , forming a dense coating layer, reducing the porosity of gold tailings. At the same time, calcium nitrite has strong oxidizing properties, and can form a passivation film on metals such as Fe and Al on the surface of gold tailings, inhibiting the oxidation reaction of metal ions and forming a stable composite oxide, forming a physical barrier; the negative charges and active hydroxyl groups on the surface of nano-montmorillonite can adsorb Cl - , SO4 2-such corrosive ions, reducing their erosion of gold tailings. At the same time, it can form a mechanical "bridging" effect by inserting into the voids on the surface of gold tailings through cation exchange interaction, enhancing the strength; Diethylene glycol butyl ether acetate can effectively disperse nano montmorillonite particles and promote the blending of calcium nitrite and nano montmorillonite to form a stable alternation, maintaining the stability of the reaction system; Hexaethyl phosphite triamide can improve the uniformity and stability of the modified liquid, preventing chemical changes or physical separation of gold tailings during stirring and soaking. Blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micro powder and incineration fly ash are used as active admixtures, providing rich silicon sources, aluminum sources and calcium sources. Red mud and carbide slag are strongly alkaline and jointly construct an alkaline environment with industrial by-product gypsum. In this environment, the stable silicon-oxygen tetrahedron and aluminum-oxygen tetrahedron network structures in the active admixtures are destroyed and depolymerized by alkaline ions (such as OH⁻), releasing active silicon, aluminum and other elements. The active ions and small molecular groups released after depolymerization react with Ca 2+ etc. to undergo a hydration reaction. The active silicon ions react with Ca 2+ , OH⁻ to form C~(A)~S~H gel. Al 3+ reacts with Ca 2+ , SO4 2- , OH⁻ etc. to generate ettringite. These hydration products grow and intertwine to form a three-dimensional network structure, tightly connecting the modified gold tailings; During this process, new chemical bonds are continuously generated. The various chemical bonds in the C~(A)~S~H gel and the special crystal structure of ettringite endow the material with high strength and stability, enhancing its ability to resist external damage. By adding an expansive agent to react with the alkaline activator to produce volume-expansive products, it can be used to compensate for the shrinkage of the system. By adding an air-entraining agent to form a microbubble buffer layer inside small precast components, the durability of the concrete is improved. By adding epoxy resin, nano-scale and micro-scale fibers, it can not only fill the microscopic voids inside the concrete, improving the density, but also enhance the interfacial strength and form a "nano-micro" dual crack resistance system, achieving multi-scale strengthening and toughening of the concrete.

[0030] (2) All small precast components for highway engineering provided in the present invention based on modified gold tailings adopt general industrial solid wastes, and their environmental protection performance meets the requirements of each project, while alleviating the environmental pollution and land occupation problems caused by the stacking of solid wastes. Detailed implementation manners

[0031] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0032] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0034] In the following examples, the content of each component is shown in Table 1.

[0035] Table 1 Chemical composition and content in each component

[0036] The waterborne epoxy resin is the Baling Petrochemical epoxy resin CYDW-100 waterborne resin, bisphenol A type low-viscosity resin.

[0037] The polycarboxylate superplasticizer is the PCA®-I series superplasticizer.

[0038] The calcium sulfoaluminate-based expansive agent is the UEA-1 expansive agent.

[0039] The alkylbenzene sulfonate-based air-entraining agent is sodium dodecylbenzene sulfonate.

[0040] The carbon nanotube fibers and graphene fibers are both commercially available, with a particle size of 15 nm.

[0041] The particle size of the millimeter-scale fibers is 3 mm.

[0042] Example 1 (1) Preparation of modified gold tailings: Dissolve 30 parts of calcium nitrite in 70 parts of water to form an alkaline solution (pH = 10.5), and sequentially add 60 parts of diethylene glycol butyl ether acetate, 15 parts of hexapropyl phosphite triamide, and 120 parts of nano-montmorillonite, and perform high-speed shear stirring (1300 rpm) for 30 min. After mixing evenly, a modified liquid is obtained; Soak 52 parts of gold tailings in the modified liquid, continuously stir for 30 min, take it out and dry and cure at 60 °C to obtain modified gold tailings.

[0043] (2) Small precast components for highway engineering based on modified gold tailings, the raw materials by weight include: 52 parts of modified gold tailings, 5 parts of activator, 26 parts of active mineral admixture, 12 parts of epoxy resin, 0.9 part of water reducer, 0.8 part of expansive agent, 0.8 part of air-entraining agent, 0.5 part of fiber and 13 parts of water.

[0044] In the activator, the mass ratio of red mud, industrial by-product gypsum and carbide slag is 12:8:3; In the active mineral admixture, the mass ratio of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micro powder and incineration fly ash is 50:18:2:8:3:5:15; In the fiber, the nano-scale fiber is graphene fiber, the millimeter-scale fiber is polyethylene fiber, and the mass ratio of the nano-scale fiber to the millimeter-scale fiber is 1:6.

[0045] (3)The preparation method of the small precast components for highway engineering based on modified gold tailings is as follows: Mix the activator and the active mineral admixture and then carry out ball milling to obtain a powder mixture; during the ball milling process, the ball-to-material ratio is 3:1, the ball milling time is 3 min, and the rotation speed is 500 r / min.

[0046] Add the modified gold tailings, powder mixture, expansive agent, air-entraining agent and fiber to the concrete mixer in sequence according to the design ratio, stir at a speed of 45 r / min for 5 min, and obtain a solid mixture after mixing evenly; Add all the water, epoxy resin and water reducer, stir at a speed of 45 r / min for 10 min, and obtain the slurry of small precast components for highway engineering based on modified gold tailings after mixing evenly; Pour the slurry of small precast components for highway engineering based on modified gold tailings into the mold to obtain the small precast components for highway engineering based on modified gold tailings.

[0047] Example 2 (1)Preparation of modified gold tailings: Dissolve 30 parts of calcium nitrite in 70 parts of water to form an alkaline solution (pH = 10.5), add 120 parts of diethylene glycol butyl ether acetate, 60 parts of hexamethylphosphorous triamide and 150 parts of nano-montmorillonite in sequence, and carry out high-speed shear stirring (1300 rpm) for 30 min to obtain a modified liquid after mixing evenly; Soak 60 parts of gold tailings in the modified liquid, continuously stir for 20 min, take them out and dry and cure at 40 °C to obtain modified gold tailings.

[0048] (2)The small precast components for highway engineering based on modified gold tailings, the raw materials include by weight: 60 parts of modified gold tailings, 6 parts of activator, 32 parts of active mineral admixture, 8 parts of epoxy resin, 2 parts of water reducer, 0.5 part of expansive agent, 0.5 part of air-entraining agent, 0.3 part of fiber, and 17 parts of water.

[0049] In the activator, the mass ratio of red mud, industrial by-product gypsum, and carbide slag is 15:5:5; In the active mineral admixture, the mass ratio of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micro powder, and incineration fly ash is 45:15:1:5:5:8:12; In the fiber, the nano-scale fiber is graphene fiber, the millimeter-scale fiber is polypropylene fiber, and the mass ratio of nano-scale fiber to millimeter-scale fiber is 2:5.

[0050] (3)The preparation method of the small precast components for highway engineering based on modified gold tailings is as follows: Mix the activator and the active mineral admixture and then perform ball milling to obtain a powder mixture; during the ball milling process, the ball-to-material ratio is 5:1, the ball milling time is 2 min, and the rotation speed is 400 r / min.

[0051] Add the modified gold tailings, powder mixture, expansive agent, air-entraining agent, and fiber to the concrete mixer in sequence according to the designed ratio, stir at a speed of 45 r / min for 10 min, and obtain a solid mixture after mixing evenly; Add all the water, epoxy resin, and water reducer, stir at a speed of 45 r / min for 5 min, and obtain the slurry of small precast components for highway engineering based on modified gold tailings after mixing evenly; Pour the slurry of small precast components for highway engineering based on modified gold tailings into the mold to obtain the small precast components for highway engineering based on modified gold tailings.

[0052] Example 3 (1)Preparation of modified gold tailings: Dissolve 30 parts of calcium nitrite in 70 parts of water to form an alkaline solution (pH = 10.5), add 20 parts of diethylene glycol butyl ether acetate, 20 parts of hexakisethylphosphorous triamide, and 100 parts of nano-montmorillonite in sequence, and perform high-speed shear stirring (1300 rpm) for 30 min to obtain a modified liquid after mixing evenly; Soak 58 parts of gold tailings in the modified liquid, continuously stir for 25 min, take out and dry and cure at 40 °C to obtain modified gold tailings.

[0053] (2)The small precast components for highway engineering based on modified gold tailings, the raw materials include by weight: 58 parts of modified gold tailings, 8 parts of activator, 32 parts of active mineral admixture, 15 parts of epoxy resin, 1.5 parts of water reducer, 1 part of expansive agent, 1 part of air-entraining agent, 0.5 part of fiber, and 15 parts of water.

[0054] In the activator, the mass ratio of red mud, industrial by-product gypsum and carbide slag is 15:10:2; In the active mineral admixture, the mass ratio of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micro powder and incineration fly ash is 55:20:3:10:8:10:10; In the fiber, the nano-scale fiber is carbon nanotube fiber, the millimeter-scale fiber is steel fiber, and the mass ratio of nano-scale fiber to millimeter-scale fiber is 1.5:7.

[0055] (3)The preparation method of the small precast components for highway engineering based on modified gold tailings is as follows: Mix the activator and the active mineral admixture and then carry out ball milling to obtain a powder mixture; during the ball milling process, the ball-to-material ratio is 2:1, the ball milling time is 3 min, and the rotation speed is 500 r / min.

[0056] Add the modified gold tailings, powder mixture, expansive agent, air-entraining agent and fiber to the concrete mixer in sequence according to the designed ratio, stir at a speed of 45 r / min for 5 min, and obtain a solid mixture after mixing evenly; Add all the water, epoxy resin and water reducer, stir at a speed of 45 r / min for 8 min, and obtain the slurry of small precast components for highway engineering based on modified gold tailings after mixing evenly; Pour the slurry of small precast components for highway engineering based on modified gold tailings into the mold to obtain the small precast components for highway engineering based on modified gold tailings.

[0057] Example 4 (1)Preparation of modified gold tailings: Dissolve 30 parts of calcium nitrite in 70 parts of water to form an alkaline solution (pH = 10.5), add 30 parts of diethylene glycol butyl ether acetate, 15 parts of hexamethylphosphorous triamide, and 75 parts of nano-montmorillonite in sequence, and carry out high-speed shear stirring (1300 rpm) for 30 min to obtain a modified liquid after mixing evenly; Soak 64 parts of gold tailings in the modified liquid, continuously stir for 30 min, take it out and dry and cure at 50 °C to obtain modified gold tailings.

[0058] (2)The small precast components for highway engineering based on modified gold tailings, the raw materials include by weight: 64 parts of modified gold tailings, 9 parts of activator, 32 parts of active mineral admixture, 10 parts of epoxy resin, 0.5 parts of water reducing agent, 1 part of expansive agent, 0.5 parts of air entraining agent, 0.1 parts of fiber, 15 parts of water.

[0059] In the activator, the mass ratio of red mud, industrial by - product gypsum and carbide slag is 10:8:5; In the active mineral admixture, the mass ratio of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate fine powder and incineration fly ash is 40:15:2:5:8:5:12; In the fiber, the nano - scale fiber is graphene fiber, the millimeter - scale fiber is steel fiber, and the mass ratio of nano - scale fiber to millimeter - scale fiber is 1:6.

[0060] (3)The preparation method of the small precast component for highway engineering based on modified gold tailings is as follows: Mix the activator and the active mineral admixture and then carry out ball milling to obtain a powder mixture; during the ball milling process, the ball - to - material ratio is 5:1, the ball milling time is 2 min, and the rotation speed is 400 r / min.

[0061] Add the modified gold tailings, powder mixture, expansive agent, air entraining agent and fiber into the concrete mixer in accordance with the designed ratio, stir at a speed of 45 r / min for 8 min, and obtain a solid mixture after mixing evenly; Add all the water, epoxy resin and water reducing agent, stir at a speed of 45 r / min for 8 min, and obtain the slurry of the small precast component for highway engineering based on modified gold tailings after mixing evenly; Pour the slurry of the small precast component for highway engineering based on modified gold tailings into the mold to obtain the small precast component for highway engineering based on modified gold tailings.

[0062] Example 5 (1)Preparation of modified gold tailings: Dissolve 30 parts of calcium nitrite in 70 parts of water to form an alkaline solution (pH = 10.5), add 20 parts of diethylene glycol butyl ether acetate, 20 parts of hexakis(ethylphosphite)triamine, and 80 parts of nano - montmorillonite in sequence, and carry out high - speed shear stirring (1300 rpm) for 30 min to obtain a modified liquid after mixing evenly; Soak 58 parts of gold tailings in the modified liquid, continuously stir for 25 min, take them out and dry and cure at 45℃ to obtain modified gold tailings.

[0063] (2)The small precast component for highway engineering based on modified gold tailings, the raw materials include by weight: 58 parts of modified gold tailings, 5 parts of activator, 28 parts of active mineral admixture, 8 parts of epoxy resin, 1.5 parts of water reducing agent, 0.8 parts of expansive agent, 0.8 parts of air entraining agent, 0.2 parts of fiber, 20 parts of water.

[0064] In the activator, the mass ratio of red mud, industrial by - product gypsum and carbide slag is 15:5:2; In the active mineral admixture, the mass ratio of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micro - powder and incineration fly ash is 52:18:3:5:6:8:14; In the fiber, the nano - scale fiber is carbon nanotube fiber, the millimeter - scale fiber is polyethylene fiber, and the mass ratio of nano - scale fiber to millimeter - scale fiber is 2:5.

[0065] (3)The preparation method of small precast components for highway engineering based on modified gold tailings is as follows: Mix the activator and the active mineral admixture and then carry out ball milling to obtain a powder mixture; during the ball milling process, the ball - to - material ratio is 4:1, the ball milling time is 2 min, and the rotation speed is 500 r / min.

[0066] Add the modified gold tailings, powder mixture, expansive agent, air entraining agent and fiber to the concrete mixer in accordance with the designed ratio, stir at a speed of 45 r / min for 10 min, and obtain a solid mixture after mixing evenly; Add all the water, epoxy resin and water reducing agent, stir at a speed of 45 r / min for 10 min, and obtain the slurry of small precast components for highway engineering based on modified gold tailings after mixing evenly; Pour the slurry of small precast components for highway engineering based on modified gold tailings into the mold to obtain the small precast components for highway engineering based on modified gold tailings.

[0067] Comparative Example 1 The raw materials of the small precast components for highway engineering are C40 ordinary concrete, among which 12 parts of P·O 425 cement, 6.8 parts of water, 35 parts of river sand, 18 parts of 5 - 10 mm limestone gravel, 28 parts of 10 - 20 mm limestone gravel, 0.2 parts of water reducing agent; pour the raw materials into the concrete mixer, stir at a speed of 45 r / min for 10 min, and obtain the slurry after mixing evenly; pour the slurry into the mold to obtain the small precast components for highway engineering.

[0068] Comparative Example 2 The difference between this comparative example and Example 1 is that: in the raw materials, 26 parts of active mineral admixture and 5 parts of activator are all replaced by 31 parts of ordinary Portland cement PO42.5 with equal parts. Other methods and steps are the same as those in Example 1 and will not be elaborated here.

[0069] Comparative Example 3 The difference between this comparative example and Example 1 is that the raw material of gold tailings is not modified. The other methods and steps are the same as those in Example 1, and will not be elaborated here.

[0070] Comparative Example 4 The difference between this comparative example and Example 1 is that the raw material does not contain an air-entraining agent. The other methods and steps are the same as those in Example 1, and will not be elaborated here.

[0071] Comparative Example 5 The difference between this comparative example and Example 1 is that the raw material does not contain an expansive agent. The other methods and steps are the same as those in Example 1, and will not be elaborated here.

[0072] Comparative Example 6 The difference between this comparative example and Example 1 is that the raw material does not contain epoxy resin. The other methods and steps are the same as those in Example 1, and will not be elaborated here.

[0073] Comparative Example 7 The difference between this comparative example and Example 1 is that the raw material does not contain fibers. The other methods and steps are the same as those in Example 1, and will not be elaborated here.

[0074] Example 6 According to JTG 3420~2020 "Test Regulations for Cement and Cement Concrete in Highway Engineering", the small precast components for highway engineering obtained in Examples 1~5 and Comparative Examples 1~7 were carried out for concrete 3d, 7d and 28d compressive strength tests, shrinkage tests and salt freeze resistance tests, and the results are shown in Table 2.

[0075] Table 2 Test Results

[0076] By comparing the effects of the examples and the comparative examples, it can be known that in Comparative Example 1 (C40 ordinary concrete), due to the non-use of gold tailings, the micro-aggregate filling effect of gold tailings and the pozzolanic reaction between gold tailings and active mineral admixtures are lacking, resulting in a higher porosity of the cement matrix, insufficient generation of C-S-H gel, and at the same time, the lack of the pore buffer mechanism of the air-entraining agent, resulting in a high salt freeze loss. In Comparative Example 2 (replacing the active admixture with ordinary cement), due to the absence of the pozzolanic reaction, Ca(OH)2 is enriched in the hydration products and reacts with Cl -The generation of expansive Friedel salts, combined with the hydration thermal cracks caused by high cement dosage, intensifies salt-freeze erosion and increases chemical shrinkage. In Comparative Example 3 (unmodified gold tailings), the clay minerals on the surface of the gold tailings adsorb free water, resulting in an increase in the water-cement ratio, weak interfacial bonding, and stress concentration. In addition, the unmodified tailings have high water absorption and interconnected pores, which intensify the freeze-thaw water migration and the swelling and shrinkage cycle. In Comparative Example 4 (without air entraining agent), due to the lack of uniformly enclosed microbubbles, the frost heave pressure cannot be released, and the penetration of the salt solution is accelerated. In Comparative Example 5 (without expansion agent), the concrete shrinkage cannot be compensated, and cracking is prone to occur. Further, the salt-freeze resistance of the concrete is reduced, and the destruction of the concrete is accelerated. In Comparative Example 6 (without epoxy resin) and Comparative Example 7 (without fiber), the microscopic voids cannot be filled, and the presence of voids makes it easier for the salt solution to penetrate. At the same time, the concrete interface strength is low and the shrinkage resistance is insufficient. In summary, Examples 1 to 5 achieved compressive strength (≥40 MPa), salt freezing resistance (stripping amount <1500g / m 2 ) and volume stability, while the comparative example destroys the multi-scale (microscopic pores~mesoscopic interface~macroscopic structure) synergistic protection network due to the lack of a single component.

[0077] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A small precast component for highway engineering based on modified gold tailings, characterized in that, The raw materials by weight include: 52 - 64 parts of modified gold tailings, 5 - 9 parts of activator, 26 - 32 parts of active mineral admixture, 8 - 15 parts of epoxy resin, 0.5 - 2 parts of water reducing agent, 0.5 - 1 part of expansive agent, 0.5 - 1 part of air entraining agent, 0.1 - 0.5 parts of fiber and 10 - 20 parts of water; The preparation method of the modified gold tailings includes the following steps: Add diethylene glycol butyl ether acetate, hexakisethylphosphorous triamide and nano - montmorillonite into the calcium nitrite aqueous solution in sequence, and obtain the modified liquid after mixing evenly; Soak the gold tailings in the modified liquid, stir, take out and dry and cure to obtain the modified gold tailings; The mass ratio of calcium nitrite, nano - montmorillonite, diethylene glycol butyl ether acetate and hexakisethylphosphorous triamide is (1 - 3):(5 - 10):(2 - 4):(1 - 2).

2. The small precast component for highway engineering based on modified gold tailings as described in claim 1, wherein The concentration of the calcium nitrite aqueous solution is 28 - 40%; The soaking time of the gold tailings in the modified liquid is 20 - 30 min; The particle size of the gold tailings is 75 - 600 μm.

3. The small precast component for highway engineering based on modified gold tailings as claimed in claim 1, wherein The activator is composed of red mud, industrial by - product gypsum and carbide slag, and the mass ratio of red mud, industrial by - product gypsum and carbide slag is (10 - 15):(5 - 10):(2 - 5).

4. The small precast component for highway engineering based on modified gold tailings according to claim 1, characterized in that, The active mineral admixture is composed of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micro - powder and incineration fly ash; the mass ratio of blast furnace slag powder, coal gangue powder, silica fume, steel slag powder, metakaolin, recycled aggregate micro - powder and incineration fly ash is (40 - 55):(15 - 20):(1 - 3):(5 - 10):(3 - 8):(5 - 10):(10 - 15).

5. The small precast member for highway engineering based on modified gold tailings as claimed in claim 1, wherein, The epoxy resin is water - based epoxy resin, with a solid content of 99% and an epoxy equivalent of 190 - 220 g / eq.

6. The small precast member for highway engineering based on modified gold tailings as described in claim 1, wherein, The water reducing agent is a polycarboxylate - based water reducing agent, and the water reducing rate is greater than 40%.

7. The small precast component for highway engineering based on modified gold tailings as claimed in claim 1, wherein, The expansive agent is calcium sulfoaluminate - based expansive agent; The air entraining agent is rosin soap - based.

8. The small precast component for highway engineering based on modified gold tailings according to claim 1, characterized in that, The fiber includes nano - scale fiber and millimeter - scale fiber, and the mass ratio of the nano - scale fiber and the millimeter - scale fiber is (1 - 2):(5 - 7); The nano - scale fiber is one of carbon nanotube fiber and graphene fiber, with a particle size of 10 - 30 nm; The millimeter - scale fiber is one of polyethylene fiber, polypropylene fiber and steel fiber, with a particle size of 2 - 4 mm.

9. The preparation method of the small precast member for highway engineering based on modified gold tailings according to any one of claims 1 to 8, characterized in that It includes the following steps: (1) Mix the activator and the active mineral admixture and then carry out ball milling to obtain a powder mixture; (2) Mix the modified gold tailings, the powder mixture, the expansive agent, the air entraining agent and the fiber evenly to obtain a solid mixture; (3) Add all the water, epoxy resin and water reducing agent to the solid mixture, and mix evenly to obtain a small precast component slurry for highway engineering based on modified gold tailings; (4) Pour the small precast component slurry for highway engineering based on modified gold tailings into a mold to obtain a small precast component for highway engineering based on modified gold tailings.

10. The preparation method according to claim 9, characterized in that, In step (1), during the ball milling process, the ball - to - material ratio is (2:1) - (5:1), the ball milling time is 2 - 3 min, and the rotation speed is 400 - 500 r / min.

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