Roadbed soil curing material based on high-doping-amount red mud and preparation method of roadbed soil curing material

Abstract

The invention discloses a roadbed soil curing material based on large-dosage red mud and a preparation method thereof, and the roadbed soil curing material is prepared from the following components in parts by mass: 80-120 parts of red mud, 4-10 parts of steel slag, 15-20 parts of blast furnace slag, 20-30 parts of iron tailings, 5-15 parts of desulfurized gypsum, 10-15 parts of alkaline residue, 5-10 parts of carbide slag, 4-6 parts of industrial sludge, 1-5 parts of salt dealkalizing agent and 1-5 parts of water stability enhancer. The roadbed soil curing material prepared by adopting the method is simple in preparation method, the compressive strength of the silty clay can be improved, the water stability of the silty clay can be effectively improved, the cured silty clay can meet the strength requirement of the roadbed soil, and efficient curing of the silty clay is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste-based materials, and specifically relates to a roadbed soil solidification material based on a large amount of red mud and a preparation method thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Silty clay is widely distributed in my country and exhibits poor water stability, low strength and bearing capacity, and difficulty in effective compaction. In areas lacking high-quality roadbed fill, silty clay cannot be used directly as a roadbed fill material. Improper handling can lead to roadbed engineering problems such as uneven settlement and cracking of the roadbed and pavement. Therefore, solidification is necessary to impart the properties of silty clay to roadbed soil, thereby meeting the requirements of roadbed fill.

[0004] Traditional methods for consolidating roadbed soil often rely on inorganic binders such as cement and lime, improving the soil through chemical modification and solidification. These materials have been developed over time and demonstrate excellent performance in enhancing roadbed strength, durability, and permeability. However, their production consumes significant fossil resources and emits significant amounts of CO2. Furthermore, their alkalinity significantly impacts the surrounding soil.

[0005] Red mud, a major solid waste generated by the aluminum industry, primarily consists of SiO2 and Al2O3. Its high alkalinity and low reactivity have made its harmless utilization a recognized challenge. Currently, red mud is primarily disposed of by stockpiling. Nationally, the stockpile exceeds 1 billion tons, with approximately 100 million tons added annually. This not only occupies significant land but also creates pollution problems. Therefore, the resourceful utilization of large quantities of red mud is crucial for the development of green, low-carbon production.

[0006] At present, some studies have begun to use solid wastes such as red mud instead of cement in different proportions to prepare soil solidification materials. However, the existing methods are either only aimed at improving strength and stability, or can only meet the requirements of solidifying heavy metal pollution factors. If red mud-based material solidified soil is used in road projects, there are still problems such as low red mud content, alkaline red mud easily affecting the surrounding environment, and poor water resistance of partially solidified roadbed soil. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a roadbed soil solidification material based on a large amount of red mud and a preparation method thereof. The solidification material takes into account both solid waste utilization and roadbed soil engineering performance, and cooperates with solid wastes such as red mud to achieve a roadbed soil solidification method with high efficiency, good water resistance and low environmental impact.

[0008] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0009] In a first aspect, the present invention provides a roadbed soil solidification material based on a large amount of red mud, which is composed of the following components in parts by mass:

[0010] 80-120 parts of red mud, 4-10 parts of steel slag, 15-20 parts of blast furnace slag, 20-30 parts of iron tailings, 5-15 parts of desulfurization gypsum, 10-15 parts of alkali residue, 5-10 parts of calcium carbide slag, 4-6 parts of industrial sludge, 1-5 parts of salt dealkalizing agent, and 1-5 parts of water stability enhancer.

[0011] In some embodiments, the roadbed soil solidification material based on a large amount of red mud is composed of the following components in parts by mass:

[0012] 80-120 parts of red mud, 4.5-8.5 parts of steel slag, 15-17.5 parts of blast furnace slag, 20-30 parts of iron tailings, 7-11 parts of desulfurization gypsum, 12-13.5 parts of alkali residue, 7-9 parts of carbide slag, 4-6 parts of industrial sludge, 1.5-3.5 parts of salt dealkalizing agent, and 1-2.7 parts of water stability enhancer.

[0013] In some embodiments, the red mud, steel slag, blast furnace slag, iron tailings, desulfurization gypsum, alkali slag, carbide slag and industrial sludge are dried and ground.

[0014] Preferably, the moisture content of each solid waste raw material is lower than 2%, and the particle size is less than 0.075 mm.

[0015] In some embodiments, the salt dealkalizing agent is selected from one or a combination of MgCl2, CaCl2, FeCl3, BaCl2 or NH4Cl.

[0016] In some embodiments, the water stability enhancer is selected from one or a combination of lignin, calcium lignin sulfonate, or sodium methyl silicate.

[0017] In a second aspect, the present invention provides a method for preparing the roadbed soil solidification material based on a large amount of red mud, comprising the following steps:

[0018] Red mud, alkali slag, carbide slag, steel slag, blast furnace slag, iron ore tailings and desulfurization gypsum are dried and ground to a particle size of less than 0.075 mm;

[0019] The ground solid waste raw materials are mixed evenly with industrial sludge and a salt-based dealkalizing agent in proportion to obtain a gelling material;

[0020] Adding water stability enhancer to the cementitious material can obtain the roadbed soil solidification material.

[0021] In a third aspect, the present invention provides a method for solidifying silty clay using the roadbed soil solidification material based on a large amount of red mud, comprising the following steps:

[0022] After the silty clay is initially screened, water is evenly sprayed to set the moisture content, and the geotextile is covered and soaked for more than 12 hours;

[0023] Add 4 to 8 parts of the roadbed soil solidification material to every 100 parts of the soaked silty clay and mix well.

[0024] In some embodiments, the set moisture content of the silty clay is 13% to 22%.

[0025] Preferably, the maximum dry density of silty clay is 1.83-1.93 g / cm 3 .

[0026] The beneficial effects achieved by one or more embodiments of the present invention are as follows:

[0027] (1) The present invention uses industrial solid wastes such as red mud, steel slag, blast furnace slag, and iron tailings slag as main raw materials, which can stimulate their gelling activity in an alkaline environment to form hydrated calcium (sodium) silicate gel similar to hydrated calcium silicate, forming a high-strength geopolymer gel skeleton inside the soil, thereby improving the stability and strength of the soil while reducing the number of free powder particles in the soil; the present invention incorporates alkali slag, calcium carbide slag and desulfurization gypsum as stimulating raw materials, wherein calcium carbide slag is the waste residue after calcium carbide is hydrolyzed to obtain acetylene gas, and its main component is calcium hydroxide, which can provide an alkaline environment for the formation of gelling materials, while desulfurization gypsum and alkali slag contain a large amount of SO4 2- and Ca 2+ It can react with Al2O3 and SiO2 in the red mud raw material to produce hydration products such as ettringite, showing a salt-stimulating effect. Alkali residue, carbide slag, and desulfurized gypsum, as industrial solid wastes, have varying degrees of stimulating effects on the hydration of cementitious materials and can replace alkaline activators to achieve waste utilization.

[0028] (2) The present invention adopts a certain amount of salt de-alkali agent and industrial sludge, and replaces the sodium ions in red mud by magnesium, calcium, nitrogen, etc. in industrial sludge and salt de-alkali agent, thereby promoting the dissolution of sodium ions from red mud, thereby achieving the purpose of efficiently neutralizing the alkalinity of red mud and reducing the environmental pollution problems caused by solid waste such as red mud to soil and water bodies.

[0029] (3) The present invention incorporates a small amount of lignin admixtures and organosilicon hydrophobic agents as water stability enhancers, which can fill the pores between silty clay particles, transform the soil from particles into a more agglomerated large particle structure, repel water molecules outside, and achieve the effect of reducing water absorption, which can effectively improve the water stability of silty clay.

[0030] (4) The roadbed soil solidification material prepared by the method of the present invention has a simple preparation method, can improve the compressive strength of silty clay, and effectively improve its water stability, so that the solidified silty clay meets the strength requirements as roadbed soil, and realizes efficient solidification of silty clay; the present invention uses a large amount of solid waste such as red mud as the main raw material to replace traditional inorganic binders to solidify roadbed soil, and achieves good results. It can effectively solve the problems of stacking and pollution of large amounts of red mud, reduce land occupation, and realize the resource utilization of red mud. The present invention has a broad application prospect for solidifying roadbed soil with red mud as the main raw material. DETAILED DESCRIPTION

[0031] It should be noted that the following detailed description is illustrative and is intended to provide further explanation 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 skilled in the art to which the present invention belongs.

[0032] The present invention will be further described below with reference to the embodiments.

[0033] Unless otherwise specified, the materials, reagents, etc. used in the examples of the present invention can be obtained from commercial sources.

[0034] Example 1

[0035] A roadbed soil solidification material based on a large amount of red mud, wherein the solidification material comprises the following components in parts by mass: 80.0 parts of red mud, 6.0 parts of steel slag, 17.0 parts of blast furnace slag, 23.5 parts of iron tailings, 7.0 parts of desulfurization gypsum, 12.5 parts of alkali slag, 9.0 parts of calcium carbide slag, 6.0 parts of industrial sludge, 2.0 parts of MgCl2, 1.5 parts of CaCl2, 1.0 part of lignin, and 1.7 parts of calcium lignin sulfonate.

[0036] The preparation and use method of the roadbed soil solidification material comprises the following steps:

[0037] S1. Preliminarily screen the silty clay soil sample, measure the moisture content, evenly spray water until the optimum moisture content is reached, and cover with geotextile to soak for more than 12 hours;

[0038] S2, drying and grinding red mud, alkali slag, carbide slag, steel slag, blast furnace slag, iron tailings slag and desulfurization gypsum to a particle size of less than 0.075 mm;

[0039] S3. Mixing the dried and ground solid waste raw materials with industrial sludge and a salt dealkalizer according to weight fractions to prepare a cementitious material. After the cementitious material is evenly mixed, a water stability enhancer is added according to weight fraction to obtain a roadbed soil solidification material.

[0040] S4. Add 4 parts of roadbed soil solidification material to the soaked silty clay for every 100 parts of soaked soil sample, and mix thoroughly until all the components are evenly mixed to prepare solidified roadbed soil.

[0041] Example 2

[0042] A roadbed soil solidification material based on a large amount of red mud, wherein the solidification material comprises the following components in parts by mass: 95.0 parts of red mud, 4.5 parts of steel slag, 15.0 parts of blast furnace slag, 20.0 parts of iron tailings, 8.0 parts of desulfurization gypsum, 12.0 parts of alkali slag, 7.5 parts of calcium carbide slag, 4.0 parts of industrial sludge, 1.0 part of MgCl2, 1.0 part of CaCl2, 1.0 part of lignin, and 1.0 part of calcium lignin sulfonate.

[0043] The preparation and use method of the roadbed soil solidification material comprises the following steps:

[0044] S1. Preliminarily screen the silty clay soil sample, measure the moisture content, evenly spray water until the optimum moisture content is reached, and cover with geotextile to soak for more than 12 hours;

[0045] S2, drying and grinding red mud, alkali slag, carbide slag, steel slag, blast furnace slag, iron tailings slag and desulfurization gypsum to a particle size of less than 0.075 mm;

[0046] S3. Mixing the dried and ground solid waste raw materials with industrial sludge and a salt dealkalizer according to weight fractions to prepare a cementitious material. After the cementitious material is evenly mixed, a water stability enhancer is added according to weight fraction to obtain a roadbed soil solidification material.

[0047] S4. Add 6 parts of roadbed soil solidification material to the soaked silty clay for every 100 parts of soaked soil sample, and mix thoroughly until all components are evenly mixed to prepare solidified roadbed soil.

[0048] Example 3

[0049] A roadbed soil solidification material based on a large amount of red mud, wherein the solidification material comprises the following components in parts by mass: 120.0 parts of red mud, 8.5 parts of steel slag, 17.5 parts of blast furnace slag, 30.0 parts of iron tailings, 11.0 parts of desulfurization gypsum, 13.5 parts of alkali slag, 7.0 parts of calcium carbide slag, 5.5 parts of industrial sludge, 1.0 part of NH4Cl2, 1.0 part of CaCl2, 0.5 part of lignin, and 0.5 part of calcium lignin sulfonate.

[0050] The preparation and use method of the roadbed soil solidification material comprises the following steps:

[0051] S1. Preliminarily screen the silty clay soil sample, measure the moisture content, evenly spray water until the optimum moisture content is reached, and cover with geotextile to soak for more than 12 hours;

[0052] S2, drying and grinding red mud, alkali slag, carbide slag, steel slag, blast furnace slag, iron tailings slag and desulfurization gypsum to a particle size of less than 0.075 mm;

[0053] S3. Mixing the dried and ground solid waste raw materials with industrial sludge and a salt dealkalizer according to weight fractions to prepare a cementitious material. After the cementitious material is evenly mixed, a water stability enhancer is added according to weight fraction to obtain a roadbed soil solidification material.

[0054] S4. Add 8 parts of roadbed soil solidification material to the soaked silty clay for every 100 parts of soaked soil sample, and mix thoroughly until all components are evenly mixed to prepare solidified roadbed soil.

[0055] Comparative Example 1

[0056] A roadbed soil solidification material based on a large amount of red mud does not contain a water stability enhancer compared to Example 1, and is otherwise the same as Example 1.

[0057] Specifically, the solidifying material includes the following components by mass: 80.0 parts of red mud, 6.0 parts of steel slag, 17.0 parts of blast furnace slag, 23.5 parts of iron tailings, 7.0 parts of desulfurized gypsum, 12.5 parts of alkali residue, 9.0 parts of calcium carbide slag, 2.0 parts of NH4Cl2, 1.0 parts of CaCl2, and 0.5 parts of BaCl2. The preparation method and usage method are the same as those in Example 1.

[0058] Comparative Example 2

[0059] A roadbed soil solidification material based on a large amount of red mud does not contain a water stability enhancer, industrial sludge, and a salt dealkalizing agent compared to Example 2.

[0060] Specifically, the solidifying material comprises the following formula, by weight: 95.0 parts red mud, 4.5 parts steel slag, 15.0 parts blast furnace slag, 20.0 parts iron tailings, 8.0 parts desulfurized gypsum, 12.0 parts alkali slag, and 7.5 parts calcium carbide slag. The preparation method and usage method are the same as those in Example 2.

[0061] Comparative Example 3

[0062] A traditional cement-stabilized soil preparation involves initially screening silty clay, measuring its moisture content, and evenly spraying water until the optimum moisture content is reached. Covering with a geotextile and allowing it to soak for at least 12 hours, 8 parts PO42.5 cement is then added to every 100 parts of the soaked soil sample. The mixture is thoroughly mixed until all ingredients are evenly incorporated, creating the cement-stabilized soil.

[0063] Comparative Example 4

[0064] A roadbed soil solidification material based on a large amount of red mud. Compared with Example 1, the roadbed soil solidification material of this comparative example does not contain a salt dealkalizing agent, and is otherwise the same as Example 1.

[0065] Specifically, the solidifying material includes the following components, by weight: 80.0 parts red mud, 6.0 parts steel slag, 17.0 parts blast furnace slag, 23.5 parts iron ore tailings, 7.0 parts desulfurized gypsum, 12.5 parts alkali residue, 9.0 parts carbide slag, 6.0 parts industrial sludge, 1.0 part lignin, and 1.7 parts calcium lignin sulfonate. The preparation and use methods are the same as those in Example 1.

[0066] Comparative Example 5

[0067] A roadbed soil solidification material based on a large amount of red mud. Compared with Example 1, the roadbed soil solidification material of this comparative example does not contain industrial sludge.

[0068] Specifically, the solidifying material includes the following components by mass: 80.0 parts red mud, 6.0 parts steel slag, 17.0 parts blast furnace slag, 23.5 parts iron tailings, 7.0 parts desulfurized gypsum, 12.5 parts alkali residue, 9.0 parts carbide slag, 2.0 parts MgCl2, 1.5 parts CaCl2, 1.0 parts lignin, and 1.7 parts calcium lignin sulfonate. The preparation method and usage are the same as those in Example 1.

[0069] Comparative Example 6

[0070] A roadbed soil solidification material based on a large amount of red mud. Compared with Example 1, the roadbed soil solidification material of this comparative example does not contain steel slag, and is otherwise the same as Example 1.

[0071] Specifically, the solidification material includes the following components in parts by mass: 80.0 parts of red mud, 17.0 parts of blast furnace slag, 23.5 parts of iron tailings, 7.0 parts of desulfurization gypsum, 12.5 parts of alkali slag, 9.0 parts of calcium carbide slag, 6.0 parts of industrial sludge, 2.0 parts of MgCl2, 1.5 parts of CaCl2, 1.0 part of lignin, and 1.7 parts of calcium lignin sulfonate.

[0072] The solidified soil specimens were prepared according to the above methods and their performance tests were carried out:

[0073] (1) According to the "Testing Procedures for Inorganic Binder Stabilized Materials for Highway Engineering" and the Chinese Cement Stabilized Soil Forming and Testing Method, the 7-day unconfined compressive strength test was conducted. The specimens were cured in a standard curing room at a temperature of (20±2)°C and a relative humidity of ≥95% for the first 6 days, and then immersed in water at (20±2)°C for the last 1 day. After 7 days, the specimens were removed and their compressive strength was measured.

[0074] (2) The water stability coefficient ξ is defined as the ratio of the 7-day standard specimen compressive strength to the 7-day dry-cured compressive strength, which is used to represent water stability. The larger the coefficient, the better the water stability.

[0075] Table 1 Mechanical strength test results of cured roadbed soil

[0076]

[0077] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A roadbed soil solidification material based on a large amount of red mud, characterized by: By mass, it is composed of the following components: 80-120 parts of red mud, 4-10 parts of steel slag, 15-20 parts of blast furnace slag, 20-30 parts of iron tailings, 5-15 parts of desulfurization gypsum, 10-15 parts of alkali residue, 5-10 parts of calcium carbide slag, 4-6 parts of industrial sludge, 1-5 parts of salt dealkalizing agent, and 1-5 parts of water stability enhancer.

2. The roadbed soil solidification material based on a large amount of red mud according to claim 1, characterized in that: By mass, it is composed of the following components: 80-120 parts of red mud, 4.5-8.5 parts of steel slag, 15-17.5 parts of blast furnace slag, 20-30 parts of iron tailings, 7-11 parts of desulfurization gypsum, 12-13.5 parts of alkali residue, 7-9 parts of carbide slag, 4-6 parts of industrial sludge, 1.5-3.5 parts of salt dealkalizing agent, and 1-2.7 parts of water stability enhancer.

3. The roadbed soil solidification material based on a large amount of red mud according to claim 1 or 2, characterized in that: The red mud, steel slag, blast furnace slag, iron tailings, desulfurized gypsum, alkali slag, carbide slag and industrial sludge are dried and ground.

4. The roadbed soil solidification material based on a large amount of red mud according to claim 3, characterized in that: The moisture content of each solid waste raw material is lower than 2%, and the particle size is less than 0.075 mm.

5. The roadbed soil solidification material based on a large amount of red mud according to claim 1, characterized in that: The salt dealkalizing agent is selected from one of MgCl2, CaCl2, FeCl3, BaCl2 or NH4Cl or a combination thereof.

6. The roadbed soil solidification material based on a large amount of red mud according to claim 1, characterized in that: The water stability enhancer is selected from one of lignin, calcium lignin sulfonate and sodium methyl silicate or a combination thereof.

7. The method for preparing a roadbed soil solidification material based on a high content of red mud according to any one of claims 1 to 6, characterized in that: The steps include: Red mud, alkali slag, carbide slag, steel slag, blast furnace slag, iron ore tailings and desulfurization gypsum are dried and ground to a particle size of less than 0.075 mm; The ground solid waste raw materials are mixed evenly with industrial sludge and a salt-based dealkalizing agent in proportion to obtain a gelling material; Adding water stability enhancer to the cementitious material can obtain the roadbed soil solidification material.

8. A method for solidifying silty clay using the roadbed soil solidification material based on a high content of red mud according to any one of claims 1 to 6, characterized in that: The steps include: After the silty clay is initially screened, water is evenly sprayed to set the moisture content, and the geotextile is covered and soaked for more than 12 hours; Add 4 to 8 parts of the roadbed soil solidification material to every 100 parts of the soaked silty clay and mix well.

9. The method for solidifying silty clay according to claim 8, wherein: The set moisture content of silty clay is 13% to 22%.

10. The method for solidifying silty clay according to claim 8, wherein: The maximum dry density of silty clay is 1.83-1.93 g / cm 3 .

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