Multi-element solid waste modified material with good corrosion resistance and preparation method of multi-element solid waste modified material

Abstract

The invention relates to a multi-element solid waste modified material with good corrosion resistance and a preparation method thereof, and relates to the technical field of resource utilization of building materials and solid waste, the material takes slag, fly ash, steel slag and other multi-element industrial solid wastes as a gelling main body, and is enhanced by combining silane modification / alkali treatment natural plant fibers; the alkali activator is prepared from Na < + >, K < + > and other components extracted from industrial waste liquid. A compact C-A-S-H gel structure is formed through a solid waste synergistic effect, and the mechanical property and the corrosion resistance are remarkably improved. Corrosion tests show that compared with a traditional cement-based material (the strength loss rate is larger than 30%), the material is lower in mechanical attenuation rate, uniform in crack distribution, excellent in ductility and outstanding in acid resistance, sulfate resistance and chloride ion erosion resistance, and is suitable for high-corrosion environments such as ocean engineering and underground facilities. According to the technology, the solid waste recycling rate exceeds 85%, the method has the advantages of being low in environmental load, long in service life, wide in adaptability and the like, and green and low-carbon transformation of the building material industry is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials and the resource utilization of solid waste, and specifically to a multi-solid waste modified material with good corrosion resistance and a preparation method thereof. Background Art

[0002] Due to problems such as high carbon emissions, high energy consumption, and resource dependence of traditional cementitious materials, they are gradually facing the pressure of being partially replaced. In recent years, low-carbon cementitious materials based on industrial solid waste have received extensive attention. Representative systems include fly ash-slag-based alkali-activated materials, steel slag-red mud composite cementitious systems, etc. These materials not only have good cementitious properties and mechanical properties, but also can effectively realize the resource utilization of bulk industrial solid waste, which is one of the important directions for the development of current green building materials.

[0003] However, the existing technologies mainly have the following problems and challenges:

[0004] (1) Single type of solid waste, insufficient broad-spectrum resource utilization

[0005] Currently, the solid waste most used in research and engineering practice still focuses on "high-quality" wastes such as fly ash and slag. These raw materials have shown the phenomenon of "tight resources" in some regions and are difficult to meet the needs of large-scale promotion. On the other hand, potential solid wastes such as steel slag, red mud, construction waste, and waste glass powder still have a low degree of co-utilization in the material system due to problems such as complex chemical composition, poor stability, and low activity, which restricts the improvement of the overall solid waste resource utilization level.

[0006] (2) Dependence on commercial alkaline products for activators, insufficient greenness

[0007] Currently, the activators used in alkali-activated cementitious materials are mainly industrial-grade chemicals such as NaOH and Na2SiO3. They not only have high costs and large carbon footprints, but also are not easy to be used on a large scale in bulk projects, which does not conform to the design concept of "green, low-carbon, and circular". In fact, in industries such as metallurgy, thermoelectric power, and chemical engineering, a large amount of waste liquid by-products rich in alkaline components such as Na + , OH - , SiO3 2- etc. are generated every year. If a process can be developed to extract and utilize them for the activation of solid waste cementitious materials, the resource utilization rate and the environmental friendliness of the materials can be significantly improved.

[0008] (3) The anti-corrosion and durability performance needs to be improved urgently

[0009] Although industrial solid waste cementitious materials have certain early strength under normal temperature curing, they may face the erosion of corrosive media such as acids, alkalis, and salts during actual service. Especially in scenarios such as groundwater, marine environments, or sewage treatment facilities, the corrosion resistance of the material directly affects the service life and safety of the structure. Currently, most alkali-activated materials have problems such as high strength loss rate, easy cracking, and interface layer damage under environments such as chloride salt erosion, acid corrosion, or sulfate wet-dry cycles, which limit their engineering applicability.

[0010] (4) The fiber reinforcement mechanism is still not perfect

[0011] Commonly used reinforcing fibers in traditional cement systems include polypropylene fibers, steel fibers, etc. In the alkali-activated material system, especially in a high pH environment, the alkali stability of the fibers becomes a key limiting factor. Natural plant fibers have the advantages of being renewable, lightweight, and highly tough, but they are easily degraded by alkaline erosion, resulting in a decrease in interfacial bonding strength. If the plant fibers can be effectively modified to improve their alkali resistance and interfacial bonding strength with C-A-S-H gel, it is expected to greatly improve the overall toughness and durability of the material.

[0012] Therefore, there is an urgent need to propose a composite cementitious material that can achieve the broad-spectrum utilization of various industrial solid wastes, prepare activators in a green and low-carbon manner, and introduce interface-stable reinforcing fibers to improve the corrosion resistance, so as to promote the engineering application of the solid waste material system in high-performance and multi-condition fields. Summary of the Invention

[0013] In order to solve the problems of the prior art, the present invention provides a multi-component solid waste modified material with good corrosion resistance and a preparation method. Using various industrial solid wastes as the main raw materials, supplemented by modified plant fiber reinforcement, and using an alkaline activator extracted from industrial waste liquid. This material not only solves the problem of the efficient and synergistic utilization of various solid wastes, but also exhibits excellent durability in a corrosive environment and is suitable for structural engineering under complex service conditions.

[0014] To solve the above technical problems, the present invention is achieved through the following technical solutions: In the first aspect, a multi-component solid waste modified material with good corrosion resistance, the composition of the material includes the following components:

[0015] Various industrial solid wastes: including but not limited to slag, fly ash, steel slag, red mud, ceramic waste powder, construction waste micro-powder, microwave-activated coal gangue powder, and at least four of them are selected for composite blending, with a total mass ratio of 60% - 90%;

[0016] Modified plant fibers: selected from including but not limited to coconut shell fibers, sisal fibers, bamboo fibers, and bagasse fibers, with a fiber length of 15 - 20 mm, a mass dosage of 0.2% - 1.0%, and modified by alkali treatment or silane coupling agent;

[0017] Alkaline activator: derived from alkaline components extracted from industrial waste liquor;

[0018] Other components: including appropriate amount of water and optional functional additives, and the water-binder ratio is controlled at 0.35 - 0.4.

[0019] In a specific embodiment of the first aspect, the slag content in industrial solid waste is 10% - 25%, the fly ash content is 10% - 30%, the steel slag content is 5% - 15%, the red mud content is 5% - 15%, and the total amount of ceramic waste powder or construction waste fine powder does not exceed 20%.

[0020] In a specific embodiment of the first aspect, the plant fiber is modified by any of the following methods:

[0021] Soaking in a 1% - 3% mass fraction of silane coupling agent solution for 4 - 12 hours;

[0022] Treating with 1M sodium hydroxide solution for 1 - 2 hours, and then neutralizing, washing and drying with distilled water;

[0023] Surface grafting of organic functional groups to improve its alkali resistance and interfacial bonding strength with the matrix.

[0024] In a specific embodiment of the first aspect, the above-mentioned alkaline activator is obtained by treating the following industrial waste liquors:

[0025] Desulfurization waste liquor; chemical industrial fluorination wastewater; thermal power waste alkali liquor; industrial by-product liquor containing alkaline ions such as Na + , K + , OH - , SiO3 2- etc.; the treatment method is to extract soluble alkali components by means of cooling precipitation, membrane separation or ion exchange.

[0026] In the second aspect, a preparation method of a multi-component solid waste modified material with good corrosion resistance is characterized by comprising the following steps:

[0027] S1: Mix the above-mentioned various industrial solid wastes according to the designed proportion and grind them to D90 < 75μm;

[0028] S2: Perform surface modification treatment on the plant fiber and dry it for standby;

[0029] S3: Treat the industrial waste liquor to obtain an alkaline activator solution and adjust its modulus;

[0030] S4: Add the industrial solid waste, fiber, activator solution and water into a mixer according to the proportion and stir evenly to obtain a slurry;

[0031] S5: Inject the slurry into a mold, pre-cure for 24 hours, and then perform 28-day standard curing.

[0032] In a specific embodiment of the second aspect, the compressive strength and flexural strength retention rate of the material after 180 days of dry-wet cycling erosion in NaCl solution or NaSO4 with different concentrations are not less than 80%.

[0033] In a specific embodiment of the first aspect, the material can be applied to the following environments:

[0034] Offshore engineering structures; underground pipe galleries and infrastructure; sewage treatment plants; road repair materials in high-humidity or high-salt environments.

[0035] In a specific embodiment of the second aspect, the material is prepared by resource utilization of industrial waste liquid and co-utilization of solid waste, has comprehensive environmental adaptability and mechanical properties, and improves the service life of alkali-activated materials in corrosive environments.

[0036] The beneficial effects of the present invention are as follows:

[0037] 1. Broad-spectrum co-utilization of multi-source solid wastes

[0038] The present invention breaks through the limitation that traditional cementitious materials mainly rely on high-activity solid wastes such as fly ash and slag, and successfully realizes the composite co-activation and stable solidification of various medium- and low-activity industrial solid wastes (including but not limited to steel slag, red mud, ceramic waste powder, waste glass powder, construction waste fine powder). It not only significantly improves the resource utilization rate of solid wastes, but also has strong regional adaptability. It can be flexibly proportioned according to the characteristics of industrial solid waste resources in different regions, enhancing the engineering promotion of the technology and the material regulation space.

[0039] 2. Green upgrading of alkaline activators to reduce carbon footprint

[0040] The activator used is derived from alkali-containing waste liquids such as metallurgical waste liquid, desulfurization waste liquid, and fluorochemical tail liquid, replacing conventional activators such as commercial NaOH and Na2SiO3 with high energy consumption, high cost, and relatively high carbon footprint, significantly reducing the environmental impact and production cost of the whole life cycle of the material. This activator system has advantages such as high stability, strong activity, and continuous extractability, providing a new path for the green transformation of alkali-activated cementitious materials.

[0041] 3. High-toughness and renewable plant fiber reinforcement mechanism

[0042] The present invention introduces modified natural plant fibers (such as coconut shell fibers, sisal fibers, bamboo fibers, etc.) as the reinforcement phase, and improves their durability in alkaline environments and interfacial bonding properties with the matrix through interfacial modification technology. Compared with traditional synthetic fibers, plant fibers have lower environmental loads and more excellent elongation at break, which can effectively improve the crack resistance, toughness and impact energy absorption capacity of the material, and enhance the overall service stability.

[0043] 4. The material is dense and uniform, with excellent corrosion resistance

[0044] Due to the special source of the activator and the balanced system formula, the formed C-A-S-H gel phase has a high degree of polymerization and density, showing extremely strong structural stability under the action of corrosive media. Through simulated tests in marine chloride corrosion (NaCl), acidic erosion, and sulfate (Na₂SO₄) environments, the invented material has significantly lower mechanical property attenuation, and the crack development of the material is also relatively uniform, showing good ductility, indicating that the material has excellent resistance to acid, sulfate, and chloride ion erosion.

[0045] 5. Controllable cost and strong process compatibility

[0046] The raw materials used in the present invention are widely present in existing industrial waste streams, with good economy; at the same time, the preparation process of this material does not require special equipment and can be compatible with conventional stirring, pouring, and curing equipment and processes, facilitating direct substitution for ordinary cement products in actual engineering projects, and having good engineering implementation and promotion potential.

[0047] 6. Suitable for engineering applications in various service environments

[0048] This material can be widely applied to structural parts in various highly corrosive, high-humidity, and high-salt environments such as subway tunnels, ocean engineering, sewage treatment plants, and water conservancy structures. It is particularly suitable for replacing traditional cement materials in "easily corroded and difficult-to-repair" areas (such as the bottom of components, underground foundations, joints, etc.) to improve the engineering life and sustainability. Description of the Drawings

[0049] Figure 1 is the schematic flow chart of the preparation of the multi-component solid waste modified material of the present invention. Detailed Embodiments

[0050] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0051] Such as Figure 1 A multi-component solid waste modified material with good corrosion resistance and a preparation method include the following steps:

[0052] S1: Raw material preparation

[0053] Mix various industrial solid waste raw materials according to the mass ratio and dry grind them to D90 < 75 μm. The industrial solid wastes used can include fly ash, granulated blast furnace slag, steel slag powder, red mud, waste glass powder, ceramic waste powder, and construction waste micro powder. The specific types of solid waste raw materials used can be selected according to the construction area and construction economy.

[0054] S2: Fiber modification treatment

[0055] Select natural plant fibers such as sisal fiber, coconut shell microfiber, and bagasse fiber, soak them in the modification solution, and dry them for standby.

[0056] S3: Preparation of green activator

[0057] Extract Na + , K + , OH - , SiO3 2- and other active ionic components from industrial waste liquids (such as metallurgical waste liquid, desulfurization waste water), and obtain an alkaline mixed activator solution through pretreatment, membrane concentration or electrodialysis, and adjust the pH of the solution to a specified value.

[0058] S4: Mixing and molding

[0059] Pour the proportioned solid waste raw materials into a mixer and dry mix slowly for 2 min to fully mix the solid waste materials; pour in the activator prepared from industrial waste liquid with a specified mass according to the water-binder ratio of 0.35 - 0.45 and stir quickly for 2 min; add the modified plant fibers while stirring and stir quickly for 2 min, then pour into a mold for molding.

[0060] S5: Curing

[0061] Cure for 28 days under standard conditions (20 ± 2 °C, RH > 90%) to obtain the final material sample.

[0062] (III) Further technical features

[0063] 1. The content of the industrial solid waste in the cementitious material accounts for 60% - 90% of the total mass;

[0064] 2. The length of the modified plant fiber is 15 - 20 mm;

[0065] 3. The content of SiO3 2- in the activator is controlled at 10% - 20% of the mass of SiO2 in the solid waste.

[0066] IV. Performance effects and test data

[0067] The materials of the present invention are verified through the following corrosion durability experiments:

[0068]

[0069] Compared with traditional cement-based materials (the strength loss rate is generally > 30%), the material of the present invention has significantly lower attenuation of mechanical properties. The crack development of the material is also relatively uniform, showing good ductility, indicating that the material has excellent resistance to acid, sulfate and chloride ion erosion.

[0070] In summary, the working principle of the present invention is as follows:

[0071] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-component solid waste modified material with good corrosion resistance, characterized in that: The composition of the material includes the following components: A variety of industrial solid wastes: including but not limited to slag, fly ash, steel slag, red mud, ceramic waste powder, construction waste micro powder, microwave-activated coal gangue powder, and at least four of them are selected for composite blending, with the total mass ratio being 60% - 90%; Modified plant fibers: selected from including but not limited to coconut shell fibers, sisal fibers, bamboo fibers, and bagasse fibers, with a fiber length of 15 - 20 mm, a mass dosage of 0.2% - 1.0%, and modified by alkali treatment or silane coupling agent; Alkaline activator: derived from the alkaline components extracted from industrial waste liquid; Other components: including appropriate water and optional functional additives, with the water-binder ratio controlled at 0.35 - 0.

4.

2. A multi-solid waste modified material with good corrosion resistance according to claim 1, characterized in that: Among the industrial solid wastes, the slag dosage is 10% - 25%, the fly ash dosage is 10% - 30%, the steel slag dosage is 5% - 15%, the red mud dosage is 5% - 15%, and the total amount of ceramic waste powder or construction waste micro powder does not exceed 20%.

3. A multi-component solid waste modified material with good corrosion resistance according to claim 1, characterized in that: The plant fibers are modified by any of the following methods: Soaking in a 1% - 3% mass fraction of silane coupling agent solution for 4 - 12 hours; Treating with 1M sodium hydroxide solution for 1 - 2 hours, and then neutralizing, washing, and drying with distilled water; Surface grafting of organic functional groups to improve its alkali resistance and interfacial bonding strength with the matrix.

4. A multi-solid waste modified material with good corrosion resistance according to claim 1, characterized in that: The alkaline activator is obtained by treating the following industrial waste liquid: Desulfurized waste liquid; chemical fluorination wastewater; thermoelectric waste alkali liquid; industrial by-product liquid containing alkaline ions including but not limited to Na + , K + , OH - , SiO3 2- ; The treatment method includes but is not limited to cooling precipitation, membrane separation or ion exchange means to extract soluble alkali components.

5. A preparation method of a multi-component solid waste modified material with good corrosion resistance, characterized in that: Including the following steps: S1: Mix a variety of industrial solid wastes according to the designed ratio and grind them to D90 < 75 μm; S2: Conduct surface modification treatment on the plant fibers and dry them for standby; S3: Treat the industrial waste liquid to obtain an alkaline activator solution and adjust its modulus; S4: Add the industrial solid wastes, fibers, activator solution, and water into a mixer according to the ratio and stir evenly to obtain a slurry; S5: Inject the slurry into a mold, pre-cure for 24 hours, and then conduct 28-day standard curing.

6. The preparation method of a multi-component solid waste modified material with good corrosion resistance according to claim 5, characterized in that: After 180 days of dry-wet cycle erosion with different concentrations of NaCl solution or NaSO4, the compressive strength and flexural strength retention rate of the material are not less than 80%.

7. A multi-solid waste modified material with good corrosion resistance according to claim 1, characterized in that: The material can be applied to the following environments: Marine engineering structures; underground pipe galleries and infrastructure; sewage treatment plants; road repair materials in high-humidity or high-salt environments.

8. A multi-solid waste modified material with good corrosion resistance according to claim 1, characterized in that: Through the resource utilization of industrial waste liquid and the collaborative utilization of solid wastes, the material has comprehensive environmental adaptability and mechanical properties, and improves the service life of alkali-activated materials in corrosive environments.

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