Red mud-based high-performance concrete curb and preparation method thereof

Abstract

The present application relates to the technical field of building material recycling, and more particularly to a red mud-based high-performance concrete curb and a preparation method thereof. The curb is prepared from a red mud-based cementitious material, sand, stone, water, a color agent and an additive through a certain preparation method, realizes high-value resource utilization of solid waste such as red mud, improves the performance of the red mud-based concrete curb, is green and environmentally friendly, has a simple preparation process, low cost, high economic benefits, and is suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to the field of building material recycling technology, and in particular to a red mud-based high-performance concrete curbstone and its preparation method. Background Technology

[0002] Red mud is a highly alkaline solid waste generated during the production of alumina, and its large-scale utilization has always been a global technological challenge. The aluminum industry discharges hundreds of millions of tons of red mud annually, with a cumulative stockpile of approximately 1.1 billion tons, occupying more than 120,000 acres of land. As a solid waste product, along with other solid wastes such as steel slag, ore slag, fly ash, desulfurization gypsum, and non-ferrous metal slag, it is currently mainly treated by "on-site landfill." The stockpiling of solid waste not only occupies and pollutes water and soil resources in large quantities, but also affects the regional ecological environment, socio-economic development, and the safety of residents' lives.

[0003] With the rapid development of highway construction, the demand for road materials is constantly increasing. As an indispensable auxiliary facility in road engineering, the use of curb stones is showing a growing trend. Concrete curb stones are mainly made from cement and aggregates, produced through mixing, vibration molding, or other processes. However, they have poor resistance to freeze-thaw damage and corrosion, leading to a shortened service life and high maintenance costs. With the continuous increase in solid waste production and the gradual enhancement of public environmental awareness, how to use locally sourced materials and rationally utilize solid waste to replace some cement or aggregates while ensuring curb stone performance and saving construction costs has become a direction for technological research and development in the industry. The comprehensive utilization of solid waste in curb stone preparation will have good economic benefits and broad application prospects. Summary of the Invention

[0004] This invention provides a red mud-based high-performance concrete curbstone and its preparation method, realizing the high-value-added resource utilization of solid wastes such as red mud, improving the performance of red mud-based concrete curbstone, being green and environmentally friendly, having a simple preparation process, low cost, and high economic benefits, and being suitable for widespread application, thus solving the problems existing in the prior art.

[0005] The technical solution adopted in this invention is:

[0006] A red mud-based high-performance concrete curbstone comprises the following raw materials in parts by weight: 300-400 parts of red mud-based cementitious material, 600-750 parts of sand, 900-1200 parts of gravel, 140-200 parts of water, 10-20 parts of colorant, and 1-5 parts of admixture.

[0007] Furthermore, the red mud-based cementitious materials are classified into Type I, Type II, and Type III red mud-based cementitious materials according to the weight percentage of red mud, with the following specific compositions; Type II and Type III red mud-based cementitious materials are preferred for the preparation of the above-mentioned red mud-based cementitious materials.

[0008] Furthermore, the red mud-based cementitious material is selected as Type II red mud-based cementitious material, which, by weight, includes: 20-40 parts red mud, 20-40 parts mineral powder, and 30-50 parts ordinary cementitious agent.

[0009] Furthermore, the ordinary binder is a mixture of ordinary grade cement and one or more of alkali metal silicates, alkali metal hydroxides, high-calcium materials, carbonates, and talc materials; the alkali metal silicate is sodium silicate or potassium silicate, and the alkali metal hydroxide is sodium hydroxide or potassium hydroxide.

[0010] Furthermore, the binder powder should not clump, the liquid should not precipitate or separate, the fineness should meet the requirement that the residue on an 80μm sieve is no more than 20%, and the modulus should be controlled between 1.2 and 2.0.

[0011] Furthermore, the sand is one or more of natural sand, manufactured sand, tailings sand, solid waste sand, steel slag sand, and stone chip sand; the gravel is one or more of crushed stone, pebbles, tailings, coal gangue, recycled aggregate, and steel slag, with a continuous particle size of 5-30mm; the colorant is iron oxide or chromium oxide; and the admixture is one or more of water-reducing agent, air-entraining agent, retarder, and early-strength agent.

[0012] Furthermore, the sand is concrete sand prepared by mixing natural sand, tailings sand, and stone chips in a mass ratio of 3:2:1; the aggregate is concrete aggregate prepared by mixing crushed stone, tailings, and coal gangue in a mass ratio of 3:1:1, with an aggregate gradation of 40% 5-10mm particle size and 60% 10-20mm particle size.

[0013] Furthermore, the sand is concrete sand prepared by mixing natural sand, solid waste sand, and steel slag sand in a mass ratio of 3:1:1; the aggregate is concrete aggregate prepared by mixing crushed stone, recycled aggregate, and steel slag in a mass ratio of 4:2:1, with an aggregate gradation of 30% 5-10mm particle size and 70% 10-20mm particle size.

[0014] Furthermore, the sand is concrete sand prepared by mixing natural sand, tailings sand, and steel slag sand in a mass ratio of 1:2:1; the aggregate is concrete aggregate prepared by mixing crushed stone, recycled aggregate, and coal gangue in a mass ratio of 2:1:2, with an aggregate gradation of 50% 5-10mm particle size and 50% 10-20mm particle size.

[0015] Furthermore, the red mud-based cementitious material is a type III red mud-based cementitious material, which, by weight, comprises: 10-20 parts red mud, 20-30 parts mineral powder, 10-15 parts gypsum, 20-40 parts fly ash, and 20-30 parts ordinary binder.

[0016] Furthermore, the gypsum is desulfurized gypsum with a moisture content of 1% after drying and a particle size of 200 mesh after grinding, which meets the requirements of "Industrial By-product Gypsum Used in Cement"; the fly ash is preferably Grade II fly ash with a moisture content of ≤2% after drying and a particle size of 200-300 mesh after grinding, and the quality requirements should meet the requirements of "Fly Ash Used in Cement and Concrete".

[0017] The present invention also provides the following technical solutions:

[0018] A method for preparing red mud-based high-performance concrete curb stones includes the following steps:

[0019] (1) Dry the wet raw material of red mud, mix it with mineral powder and dry ordinary binder in proportion and grind it to obtain type II red mud-based cementitious material; or, dry the wet raw materials of red mud, gypsum and fly ash, mix them with mineral powder and dry ordinary binder in proportion and grind them to obtain type III red mud-based cementitious material.

[0020] (2) Prepare sand and gravel for later use;

[0021] The sand material is made by mixing natural sand, tailings sand, and stone chips in a mass ratio of 3:2:1; the gravel material is made by mixing crushed stone, tailings, and coal gangue in a mass ratio of 3:1:1, with the gravel gradation being 40% of 5-10mm particle size and 60% of 10-20mm particle size.

[0022] (3) Mix the above red mud-based cementitious materials, sand, gravel and colorant in proportion, and add the admixture to dissolve in water. During the mixing process, slowly add the admixture solution. After all the admixture is added, continue mixing for 3-5 minutes. After mixing, pour out the mixture and manually stir it for 2-4 minutes to obtain solid waste-based concrete.

[0023] (4) Apply oil to the inner wall of the curbstone mold, put solid waste-based concrete into the curbstone mold and tamp and vibrate it, let it stand for 1-2 days and nights, remove the mold, and obtain solid waste-based concrete curbstone.

[0024] (5) Place the solid waste-based concrete curbstone in a standard curing room for curing. After reaching the required age, apply a coating to the surface of the concrete curbstone and conduct testing and verification.

[0025] Further, in step (1), the red mud selected is Bayer process red mud that has been stockpiled for 3-12 months, with a moisture content of ≤3% after drying and a particle size of 300-400 mesh after grinding; the ore powder selected is S95 grade blast furnace slag powder with a moisture content of ≤1% and a specific surface area of ​​400-450 m². 2 / kg.

[0026] Further, in step (5), the age range is selected as 7 days, 28 days, 90 days, or 180 days.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention breaks through the traditional ideas and limitations of solid waste resource utilization. It uses red mud with physical activation and chemical stimulation to prepare a high-value-added red mud-based cementitious material. This red mud-based cementitious material is mainly composed of red mud, mineral powder, and cementing agent, or with the addition of gypsum and fly ash. The material composition is simplified and synergistic. Among them, the alkaline component of red mud has an activation effect on mineral powder, forming a multi-component polymer cementitious material under the action of ordinary cementing agent. In addition to participating in hydration reaction, the multi-source solid waste synergistic system of red mud-based cementitious material, sand, and gravel also undergoes geological polymerization reaction to generate N-(C)-SAH gel, CSAH gel, CSH gel, and zeolite structure crystal hydration products. The gel and crystal fill each other to form a dense structure, which greatly improves the strength performance. This solves the technical bottleneck problems such as large fluctuations in the chemical composition of solid waste, low hydration and cementing activity, poor volume stability, and pollution of soil and groundwater. The sand and stone materials are made from multiple solid waste sources and mixed in a specific ratio. This ensures effective compatibility with red mud-based cementitious materials while making full use of waste resources and saving costs.

[0029] 2. The red mud-based cementitious material prepared by this invention can directly replace traditional silicate cement, effectively avoiding the serious environmental pollution caused by limestone calcination during silicate cement production. It saves resources, reduces material costs, releases land resources, and completely eliminates the need for silicate cement. Using this invention to prepare curb stones can reduce CO2 emissions by 91.7% and energy consumption by 83.9%, demonstrating broad social, economic, and ecological benefits.

[0030] 3. Compared with ordinary concrete curb stones, the red mud-based high-performance concrete curb stones prepared by this invention use red mud-based cementitious materials to replace cement, and tailings sand, stone chips, solid waste sand, steel slag sand, etc. to replace natural sand and manufactured sand. Tailings stone, coal gangue, recycled aggregate, and steel slag are used to replace crushed stone or pebbles. The comprehensive utilization rate of solid waste exceeds 70%, which solves the problems of large land occupation, difficult treatment, and impact on the surrounding environment of waste. It also reduces the excessive mining of natural sand and gravel, saves a lot of primary mineral resources, and has a lower cost, higher early strength, and stronger resistance to salt and frost erosion while ensuring the excellent performance of the curb stones.

[0031] 4. The red mud-based high-performance concrete curbstone of this invention reduces the unit water consumption and improves the impermeability by adding admixtures. The anti-corrosion coating blocks the penetration of external media and improves the corrosion resistance. The coloring agent beautifies the product appearance, effectively eliminating public doubts and concerns about red mud products, and playing a role in warning pedestrians and drivers and alleviating driving fatigue. Detailed Implementation

[0032] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific implementation methods.

[0033] Example 1

[0034] A red mud-based high-performance concrete curbstone, made from the following components by weight:

[0035] Type II red mud-based cementitious material 400 parts, sand 740 parts, gravel 1080 parts, water 180 parts, colorant 17 parts, admixture 3 parts;

[0036] The aforementioned Type II red mud-based cementitious material, by weight, comprises the following components: 22 parts red mud, 30 parts mineral powder, and 48 parts ordinary binder, mixed evenly. The ordinary binder is prepared by mixing ordinary grade cement and sodium silicate in a 3:1 mass ratio; it is a solid powder with a sodium silicate modulus of 1.2, conforming to the requirements of "Industrial Sodium Silicate". The red mud selected is Bayer process red mud stored for 6 months, dried to a moisture content of 3%, and ground to a particle size of 300 mesh, conforming to the requirements of "Technical Specification for Application of Red Mud (Bayer Process) Subgrade in Highway Engineering". The mineral powder is S95 grade blast furnace slag powder with a moisture content of 0.7% and a specific surface area of ​​436 m². 2 / kg, which complies with the requirements of "Granulated Blast Furnace Slag Powder for Use in Cement, Mortar and Concrete".

[0037] The above-mentioned sand material is a concrete sand prepared by mixing natural sand, tailings sand and stone chips in a mass ratio of 3:2:1, and after processing, it meets the requirements of the "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete".

[0038] The above-mentioned aggregate is concrete aggregate made by mixing crushed stone, tailings, and coal gangue in a mass ratio of 3:1:1. The aggregate gradation is 40% 5-10mm particle size and 60% 10-20mm particle size. After processing, it meets the requirements of the "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete".

[0039] The colorant is an iron oxide pigment, which can be directly mixed into cementitious materials for application, in accordance with the regulations for "Iron Oxide Pigments";

[0040] The admixture is a mixture of polycarboxylate superplasticizer and polycarboxylate-specific air-entraining agent in a mass ratio of 30:1. It is a solid powder and conforms to the "Technical Specification for Application of Concrete Admixtures".

[0041] The preparation steps include:

[0042] Step 1: Dry the wet red mud raw material, and then mix and grind the dry materials such as red mud, mineral powder, and ordinary binder in the above proportion to obtain Type II red mud-based cementitious material;

[0043] Step 2: Mix natural sand, tailings sand, and stone chips in the above proportions, and optimize their performance to obtain concrete sand. Then mix crushed stone, tailings, and coal gangue in the above proportions, and optimize their performance to obtain concrete aggregate.

[0044] Step 3: Mix the Type II red mud-based cementitious material, concrete sand, concrete gravel, and colorant according to the proportion. At the same time, add the admixture to the water to dissolve it. During the mixing process, slowly add the aqueous solution. After all the solution is added, continue mixing for 3 minutes. Pour it out and manually stir it for 2 minutes to obtain solid waste-based concrete.

[0045] Step 4: Select multiple types of curbstone molds, apply oil to the inner wall, put solid waste-based concrete into the molds and tamp and vibrate it, let it stand for 1-2 days and nights, then remove the molds to obtain solid waste-based concrete curbstones.

[0046] Step 5: Place the intact solid waste-based concrete curbstones in a standard curing room and cure them for 7 days, 28 days, 90 days, and 180 days respectively. After reaching the curing age, apply a coating to the surface of the curbstones and conduct tests and verifications on items such as appearance quality, dimensional deviation, mechanical properties, and physical properties.

[0047] Example 2

[0048] A red mud-based high-performance concrete curbstone is made of the following components by weight: 350 parts of Type II red mud-based cementitious material, 680 parts of sand, 1200 parts of gravel, 170 parts of water, 18 parts of colorant, and 2 parts of admixture.

[0049] The above-mentioned Type II red mud-based cementitious material comprises the following components by weight: 38 parts red mud, 32 parts mineral powder, and 30 parts ordinary binder; the ordinary binder is a mixture of ordinary grade cement and sodium silicate in a mass ratio of 5:1, in solid powder form, with a sodium silicate modulus of 1.2, conforming to the requirements of "Industrial Sodium Silicate".

[0050] The aforementioned red mud was selected from Bayer process red mud that had been stockpiled for 12 months. After drying, the moisture content was 2%, and the particle size after grinding was 400 mesh, which meets the requirements of the "Technical Specification for Application of Red Mud (Bayer Process) in Roadbed of Highway Engineering". The mineral powder was S95 grade blast furnace slag powder with a moisture content of 0.7% and a specific surface area of ​​436 m². 2 / kg, which complies with the requirements of "Granulated Blast Furnace Slag Powder for Use in Cement, Mortar and Concrete".

[0051] The above-mentioned sand material is made by mixing natural sand, solid waste sand and steel slag sand in a mass ratio of 3:1:1, and after processing, it meets the requirements of the "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete".

[0052] The above-mentioned aggregate is made by mixing crushed stone, recycled aggregate and steel slag in a mass ratio of 4:2:1. The aggregate gradation is 30% with a particle size of 5-10mm and 70% with a particle size of 10-20mm. After processing, it meets the requirements of the "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete".

[0053] The aforementioned coloring agent is chromium oxide pigment, which is directly added to cementitious materials and complies with the regulations for "Chromium Oxide Green Pigment". The admixtures are polycarboxylate superplasticizer and polycarboxylate-specific air-entraining agent, with a mass ratio of 50:1, in solid powder form, and comply with the "Technical Specification for Application of Concrete Admixtures".

[0054] The preparation steps include:

[0055] Step 1: Dry the wet red mud raw material, and then mix and grind the dry materials such as red mud, mineral powder, and ordinary binder in a certain proportion to obtain Type II red mud-based cementitious material;

[0056] Step 2: Mix natural sand, solid waste sand, and steel slag sand in the above proportions, optimize their performance to obtain concrete sand, and then mix crushed stone, recycled aggregate, and steel slag in the above proportions, optimize their performance to obtain concrete aggregate.

[0057] Step 3: Mix the Type II red mud-based cementitious material, concrete sand, concrete gravel, and colorant according to the proportion. At the same time, add the admixture to the water to dissolve it. During the mixing process, slowly add the aqueous solution. After all the solution is added, continue mixing for 5 minutes. Pour it out and manually stir for 4 minutes to obtain solid waste-based concrete.

[0058] Step 4: Select multiple types of curbstone molds, apply oil to the inner wall, put solid waste-based concrete into the molds and tamp and vibrate it, let it stand for 1-2 days and nights, then remove the molds to obtain solid waste-based concrete curbstones.

[0059] Step 5: Place the intact solid waste-based concrete curbstones in a standard curing room and cure them for 7 days, 28 days, 90 days, and 180 days respectively. After reaching the curing age, apply a coating to the surface of the curbstones and conduct tests and verifications on items such as appearance quality, dimensional deviation, mechanical properties, and physical properties.

[0060] Example 3

[0061] A red mud-based high-performance concrete curbstone is made of the following components by weight: 380 parts of Type II red mud-based cementitious material, 830 parts of sand, 1000 parts of gravel, 190 parts of water, 19 parts of colorant, and 1 part of admixture.

[0062] The above-mentioned Type II red mud-based cementitious material comprises the following components by weight: 32 parts red mud, 30 parts mineral powder, and 38 parts ordinary binder; the ordinary binder is a mixture of ordinary grade cement and sodium silicate in a mass ratio of 4:1, in solid powder form, with a sodium silicate modulus of 1.2, conforming to the requirements of "Industrial Sodium Silicate".

[0063] The aforementioned red mud is Bayer process red mud that has been stockpiled for 3 months. After drying, its moisture content is 3%, and after grinding, the particle size is 300 mesh, which meets the requirements of the "Technical Specification for Application of Red Mud (Bayer Process) in Roadbed of Highway Engineering". The mineral powder is S95 grade blast furnace slag powder with a moisture content of 0.7% and a specific surface area of ​​436 m². 2 / kg, which complies with the requirements of "Granulated Blast Furnace Slag Powder for Use in Cement, Mortar and Concrete".

[0064] The above-mentioned sand material is made by mixing natural sand, tailings sand and steel slag sand in a mass ratio of 1:2:1, and after processing, it meets the requirements of the "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete".

[0065] The above-mentioned aggregate is made by mixing crushed stone, recycled aggregate, and coal gangue in a mass ratio of 2:1:2. The aggregate gradation is 50% 5-10mm particle size and 50% 10-20mm particle size. After processing, it meets the requirements of the "Standard for Quality and Inspection Methods of Sand and Stone for Ordinary Concrete".

[0066] The aforementioned colorant is an iron oxide pigment, which can be directly mixed into cementitious materials for application, in accordance with the regulations for "Iron Oxide Pigments".

[0067] The above-mentioned admixtures are polycarboxylate superplasticizer and polycarboxylate special air-entraining agent, with a mass ratio of 50:1, in solid powder form, and conform to the "Technical Specification for Application of Concrete Admixtures".

[0068] The preparation steps include:

[0069] Step 1: Dry the wet red mud raw material, and then mix and grind the dry materials such as red mud, mineral powder, and ordinary binder in a certain proportion to obtain Type II red mud-based cementitious material;

[0070] Step 2: Mix natural sand, tailings sand, and steel slag sand in the above proportions, and optimize their performance to obtain concrete sand. Then mix crushed stone, recycled aggregate, and coal gangue in the above proportions, and optimize their performance to obtain concrete aggregate.

[0071] Step 3: Mix the Type II red mud-based cementitious material, concrete sand, concrete gravel, and colorant according to the proportion. At the same time, add the admixture to the water to dissolve it. During the mixing process, slowly add the aqueous solution. After all the solution is added, continue mixing for 4 minutes. Pour it out and manually stir it for 3 minutes to obtain solid waste-based concrete.

[0072] Step 4: Select multiple types of curbstone molds, apply oil to the inner wall, put solid waste-based concrete into the molds and tamp and vibrate it, let it stand for 1-2 days and nights, then remove the molds to obtain solid waste-based concrete curbstones.

[0073] Step 5: Place the intact solid waste-based concrete curbstones in a standard curing room and cure them for 7 days, 28 days, 90 days, and 180 days respectively. After reaching the curing age, apply a coating to the surface of the curbstones and conduct tests and verifications on items such as appearance quality, dimensional deviation, mechanical properties, and physical properties.

[0074] Example 4

[0075] The red mud-based high-performance concrete curbstone is the same as the curbstone in Example 1, except that the Type II red mud-based cementitious material is replaced by the Type I red mud-based cementitious material. The Type I red mud-based cementitious material, by weight, includes the following components: 52 parts red mud, 37 parts mineral powder, 9 parts gypsum, and 6 parts high-efficiency binder.

[0076] The high-efficiency binder is a mixture of high-grade cement and sodium silicate in a mass ratio of 2:1. It is a solid powder with a sodium silicate modulus of 1.8, and the sodium silicate conforms to the requirements of "Industrial Sodium Silicate".

[0077] Example 5

[0078] The red mud-based high-performance concrete curbstone is the same as the curbstone in Example 1, except that the Type II red mud-based cementitious material is replaced by the Type III red mud-based cementitious material. The Type III red mud-based cementitious material, by weight, includes the following components: 13 parts red mud, 22 parts mineral powder, 12 parts gypsum, 33 parts fly ash, and 20 parts ordinary binder. The ordinary binder is a mixture of ordinary grade cement and sodium silicate in a mass ratio of 3:1, in solid powder form, with a sodium silicate modulus of 1.4, which meets the requirements of "Industrial Sodium Silicate".

[0079] In the preparation steps, gypsum, wet fly ash, and red mud are dried together, and the other steps are the same as in Example 1.

[0080] Example 6

[0081] The red mud-based high-performance concrete curbstone is the same as the curbstone in Example 2, except that the Type II red mud-based cementitious material is replaced by the Type I red mud-based cementitious material. The Type I red mud-based cementitious material, by weight, includes the following components: 67 parts red mud, 25 parts mineral powder, 8 parts gypsum, and 5 parts high-efficiency binder. The high-efficiency binder is a mixture of high-grade cement and sodium silicate in a mass ratio of 2:1, in solid powder form, with a sodium silicate modulus of 1.8, and the sodium silicate conforms to the requirements of "Industrial Sodium Silicate".

[0082] Example 7

[0083] The red mud-based high-performance concrete curbstone is the same as the curbstone in Example 2, except that the Type II red mud-based cementitious material is replaced by the Type III red mud-based cementitious material. The Type III red mud-based cementitious material, by weight, includes the following components: 20 parts red mud, 22 parts mineral powder, 12 parts gypsum, 20 parts fly ash, and 26 parts ordinary binder. The ordinary binder is a mixture of ordinary grade cement and sodium silicate in a mass ratio of 3:1, in solid waste powder form, with a sodium silicate modulus of 1.4, which meets the requirements of "Industrial Sodium Silicate".

[0084] In the preparation steps, gypsum, wet fly ash, and red mud are dried together, and the other steps are the same as in Example 2.

[0085] Example 8

[0086] The red mud-based high-performance concrete curbstone is the same as the curbstone in Example 3, except that the Type II red mud-based cementitious material is replaced by the Type I red mud-based cementitious material. The Type I red mud-based cementitious material, by weight, includes the following components: 45 parts red mud, 39 parts mineral powder, 9 parts gypsum, and 7 parts high-efficiency binder.

[0087] The high-efficiency binder is a mixture of high-grade cement and sodium silicate in a mass ratio of 2:1. It is a solid powder with a sodium silicate modulus of 1.8, which meets the requirements of "Industrial Sodium Silicate".

[0088] Example 9

[0089] The red mud-based high-performance concrete curbstone is the same as the curbstone in Example 3, except that the Type II red mud-based cementitious material is replaced by the Type III red mud-based cementitious material. The Type III red mud-based cementitious material, by weight, includes the following components: 15 parts red mud, 20 parts mineral powder, 10 parts gypsum, 27 parts fly ash, and 28 parts ordinary binder. The ordinary binder is a mixture of ordinary grade cement and sodium silicate in a mass ratio of 3:1, in solid waste powder form, with a sodium silicate modulus of 1.4, which meets the requirements of "Industrial Sodium Silicate".

[0090] In the preparation steps, gypsum, wet fly ash, and red mud are dried together, and the other steps are the same as the preparation process in Example 3.

[0091] Comparative Example 1

[0092] The difference from Example 1 is that the red mud-based cementitious material in Example 1 was replaced with P.O42.5 ordinary Portland cement.

[0093] Comparative Example 2

[0094] The difference from Example 2 is that the red mud-based cementitious material in Example 2 was replaced with P.O42.5 ordinary Portland cement.

[0095] Comparative Example 3

[0096] The difference from Example 3 is that the red mud-based cementitious material in Example 3 was replaced with P.O42.5 ordinary Portland cement.

[0097] Comparative Example 4

[0098] The difference from Example 1 is that the sand material in Example 1 is replaced with natural sand, and the gravel is replaced with crushed stone or pebbles.

[0099] Comparative Example 5

[0100] The difference from Example 2 is that the sand material in Example 2 is replaced with natural sand, and the gravel material is replaced with crushed stone or pebbles.

[0101] Comparative Example 6

[0102] The difference from Example 3 is that the sand material in Example 3 is replaced with natural sand, and the gravel material is replaced with crushed stone or pebbles.

[0103] The performance of the red mud-based concrete cementitious material prepared according to the "Test Procedures for Cement and Cement Concrete in Highway Engineering" and "Concrete Curbstones" was tested, along with the curbstones of Examples 1-9 and Comparative Examples 1-6. The test results are shown in Tables 1 and 2.

[0104] Table 1. Performance test results of red mud-based cementitious materials

[0105]

[0106] As shown in Table 1 above, the Type II red mud-based cementitious material prepared by this invention exhibits excellent mechanical properties. In particular, the red mud-based cementitious material prepared in the examples shows a maximum 28-day compressive strength of 52.7 MPa and a maximum 28-day flexural strength of 10.3 MPa, meeting the technical standards for 42.5# cement. The Type I red mud-based cementitious material has poorer mechanical properties, with a maximum 28-day compressive strength of 37.8 MPa and a maximum 28-day flexural strength of 5.8 MPa. While meeting the technical standards for 32.5# cement, the analysis indicates that the red mud has a high alkali content, with the main alkaline component being sodium. The soluble sodium component mainly exists in the form of sodium bicarbonate and sodium carbonate, accounting for 7.88-10.50% and 4.99-7.06% of the sodium component, respectively. When the red mud content in the cementitious material is too high, alkaline substances easily precipitate, causing efflorescence on the material surface. Meanwhile, the chemical composition of red mud is mainly Al2O3, SiO2, and Fe2O3, and its mineral composition includes hydrated calcium zeolite, nepheline, calcite, illite, hydrated sodium aluminosilicate, hematite, etc. It has low cementitious activity, and when the amount of red mud in the cementitious material is too high, it is not conducive to strength formation, resulting in insufficient material strength. Considering the large-scale consumption of industrial solid waste such as red mud, the Type I red mud-based cementitious material prepared by this invention is recommended; considering the product performance and quality, the Type II red mud-based cementitious material prepared by this invention is recommended.

[0107] Table 2. Performance test results of red mud-based high-performance concrete curbstones

[0108]

[0109] Table 2 shows the performance test results. Examples 1 and 3 achieved a compressive strength of C45; Examples 2, 5, 7, and 9 achieved a compressive strength of C40; Examples 4 and 8 achieved a compressive strength of C35; and Example 6 achieved a compressive strength of C30. This indicates that Examples 1-3, 5, 7, and 9 of this invention possess good compressive strength. Compared to Type I, Type II red mud-based cementitious material has a more significant effect in the preparation of high-performance red mud-based concrete curbs. High-performance red mud-based concrete curbs were prepared by combining tailings sand, stone chips, coal gangue, recycled aggregate, steel slag, and other sand and gravel solid wastes with red mud-based cementitious materials after optimized treatment. The appearance quality, dimensional deviation, mechanical properties, and physical properties all meet the requirements for concrete curbs. Compared to ordinary concrete curbs, the red mud-based concrete curbs of this invention have certain performance advantages. While fully utilizing red mud-based solid waste materials and protecting the environment, it also saves resources, resulting in significant economic benefits and broad application prospects.

[0110] The above specific embodiments should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, any alternative improvements or modifications made to the embodiments of the present invention shall fall within the scope of protection of the present invention.

[0111] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A red mud-based high-performance concrete curbstone, characterized in that, The raw materials include the following parts by weight: 300-400 parts red mud-based cementitious material, 600-750 parts sand, 900-1200 parts gravel, 140-200 parts water, 10-20 parts colorant, and 1-5 parts admixture. The red mud-based cementitious material comprises, by weight, 20-40 parts red mud, 20-40 parts mineral powder, and 30-50 parts ordinary binder; the ordinary binder is a mixture of ordinary grade cement and sodium silicate. The sand is a concrete sand made by mixing natural sand, tailings sand and stone chips in a mass ratio of 3:2:1; the gravel is a concrete gravel made by mixing crushed stone, tailings and coal gangue in a mass ratio of 3:1:1, with a gravel gradation of 40% 5-10mm particle size and 60% 10-20mm particle size. The additives are water-reducing agents and air-entraining agents.

2. The red mud-based high-performance concrete curbstone according to claim 1, characterized in that, The sand material is one or more of the following: natural sand, manufactured sand, tailings sand, solid waste sand, steel slag sand, and stone chip sand; the gravel is one or more of the following: crushed stone, pebbles, tailings, coal gangue, recycled aggregate, and steel slag, with a continuous particle size of 5-30mm; the colorant is iron oxide or chromium oxide.

3. A method for preparing red mud-based high-performance concrete curb stones, characterized in that, The following steps are included: (1) Dry the wet raw material of red mud and mix it with mineral powder and dry ordinary binder in proportion and grind it to obtain type II red mud-based cementitious material; or, dry the wet raw materials of red mud, gypsum and fly ash and mix them with mineral powder and dry ordinary binder in proportion and grind them to obtain type III red mud-based cementitious material. (2) Prepare sand and gravel for later use; The sand material is made by mixing natural sand, tailings sand, and stone chips in a mass ratio of 3:2:1; the gravel material is made by mixing crushed stone, tailings, and coal gangue in a mass ratio of 3:1:1, with the gravel gradation being 40% of 5-10mm particle size and 60% of 10-20mm particle size. (3) Mix the above red mud-based cementitious materials, sand, gravel and colorant in proportion, and add the admixture to dissolve in water. During the mixing process, slowly add the admixture solution. After all the admixture is added, continue mixing for 3-5 minutes. After mixing, pour out the mixture and manually stir it for 2-4 minutes to obtain solid waste-based concrete. (4) Apply oil to the inner wall of the curbstone mold, put solid waste-based concrete into the curbstone mold and tamp and vibrate it, let it stand for 1-2 days and nights, remove the mold, and obtain solid waste-based concrete curbstone. (5) Place the solid waste-based concrete curbstone in a standard curing room for curing. After reaching the required age, apply a coating to the surface of the concrete curbstone and conduct testing and verification.

4. The method for preparing red mud-based high-performance concrete curb stones according to claim 3, characterized in that, Step (1) Select Bayer process red mud that has been stored for 3-12 months, with a moisture content of ≤3% after drying, and a particle size of 300-400 mesh after grinding; select S95 grade blast furnace slag powder with a moisture content of ≤1% and a specific surface area of ​​400-450 m². 2 / kg.

5. The method for preparing red mud-based high-performance concrete curb stones according to claim 3, characterized in that, In step (1), the gypsum is desulfurized gypsum with a moisture content of ≤1% after drying and a particle size of 150-200 mesh after grinding; the fly ash is Class II fly ash with a moisture content of ≤2% after drying and a particle size of 200-300 mesh after grinding.

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