High-content steel slag-cement-bentonite vertical diaphragm wall material and preparation method thereof

Abstract

The invention relates to a high-content steel slag-cement-bentonite vertical diaphragm wall material and a preparation method thereof, and belongs to the technical field of building materials, the high-content steel slag-cement-bentonite vertical diaphragm wall material comprises the following raw materials: steel slag, cement, bentonite and water; wherein the mass ratio of the sum of the steel slag and the cement to the water is 1: (6-7); the bentonite accounts for 50-54% of the total mass of the steel slag, the cement and the bentonite; the mass ratio of the cement to the steel slag is (1-11): 1. According to the invention, the steel slag is adopted to replace part of cement, and the ratio of the raw materials is optimized, so that the dual problems of resource utilization of the steel slag and improvement of the performance of the anti-seepage material are solved, and the anti-seepage performance of the vertical anti-seepage wall material is improved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to a high-content steel slag-cement-bentonite vertical anti-seepage wall material and a preparation method thereof. Background Art

[0002] In recent years, as the scale of infrastructure construction in my country continues to expand, the consumption of cement, a traditional cementitious material, has risen sharply. However, a large amount of carbon dioxide emissions are generated during the production of cement, accounting for about one-third of the national total, and has become a core problem restricting the green and low-carbon transformation of the industry. At the same time, the steel industry produces a huge amount of solid waste, among which steel slag, as the main by-product of the steelmaking process, has an annual output of more than 160 million tons, but its comprehensive utilization rate has been below 30% for a long time. Steel slag includes various oxides formed by the oxidation of impurities such as silicon, manganese, phosphorus, and sulfur in pig iron during the smelting process, as well as salts generated by the reaction of these oxide solvents. The open-air storage of large amounts of steel slag not only encroaches on land resources, but also the heavy metals and alkaline substances it contains are more likely to pollute the soil and groundwater through rainwater leaching, posing serious environmental risks.

[0003] At present, cement-bentonite anti-seepage walls are widely used in dam foundation curtains, mixing piles, stone dam anti-seepage systems, landfills and other projects because of their anti-seepage performance and structural strength. However, existing technologies generally rely on a high proportion of cement as a cementing component, resulting in high material costs and significant carbon footprints. In order to reduce the amount of cement used, some studies have tried to use industrial waste residues such as fly ash and slag as a substitute. However, there is still a lack of systematic exploration of the gelling activity of steel slag, which has a lower cost, and its application in anti-seepage systems. Although steel slag contains potentially active minerals such as dicalcium silicate and dicalcium ferrite, its composition fluctuates greatly, its hydration activity is low, and its alkalinity range is wide. As a result, when it directly replaces cement, it is easy to cause problems such as material strength degradation and unstable permeability coefficient, making it difficult to meet the long-term service requirements of anti-seepage walls.

[0004] In view of the above-mentioned technical phenomena, the design of traditional anti-seepage materials often ignores the coordinated optimization of steel slag dosage, bentonite ratio and water-cement ratio, which makes it difficult to balance material performance and environmental benefits. Therefore, how to achieve high-dosage replacement of cement with steel slag through precise mix design while ensuring that the material permeability, fluidity and durability meet engineering requirements is still a technical bottleneck that needs to be broken through in this field. Summary of the invention

[0005] The purpose of the present invention is to provide a high-content steel slag-cement-bentonite vertical anti-seepage wall material and a preparation method thereof, aiming to solve the dual problems of steel slag resource utilization and anti-seepage material performance improvement by designing the ratio between steel slag, cement and bentonite.

[0006] On the one hand, the high-volume steel slag-cement-bentonite vertical cut-off wall material provided by the present invention and its preparation method adopt the following technical solutions:

[0007] The high-volume steel slag-cement-bentonite vertical cut-off wall material is characterized by comprising the following raw materials: steel slag, cement, bentonite and water;

[0008] Among them, the mass ratio of the sum of the masses of steel slag and cement to the mass of water is 1:(6-7);

[0009] The bentonite accounts for 50-54% of the total mass of steel slag, cement and bentonite;

[0010] The mass ratio of cement to steel slag is (1-11):1.

[0011] Preferably, the steel slag includes dicalcium silicate, dicalcium ferrite and RO phase.

[0012] Preferably, the basicity of the steel slag is 1.6-2.4;

[0013] The particle size of the steel slag is 200-400 mesh.

[0014] Preferably, the bentonite is a clay rock with a montmorillonite content of not less than 50%.

[0015] On the other hand, the present invention also provides a preparation method of a high-volume steel slag-cement-bentonite vertical cut-off wall material, including the following preparation methods:

[0016] S1. Weigh water and bentonite respectively, and stir fully until there are no particles to obtain bentonite slurry;

[0017] S2. Weigh cement and steel slag respectively and place them in the bentonite slurry prepared in step S1, and stir fully until there are no particles to obtain a mixed slurry;

[0018] S3. Prepare a mold, coat the inner wall of the mold with vaseline and set it aside. Pour the mixed slurry prepared in step S2 into the mold in three layers. After the mixed slurry is formed, demold it to obtain a specimen;

[0019] S4. Place the specimen prepared in step S3 in a curing box for curing to obtain a vertical cut-off wall material.

[0020] Preferably, in the three-layer mixed slurry in step S3, the height of each layer of slurry is the same, and it needs to be vibrated multiple times during the pouring process of each layer of concrete slurry.

[0021] Preferably, the temperature of the curing box in step S4 is 18-22°C and the relative humidity is 98%.

[0022] Preferably, the fluidity of the vertical cut-off wall material prepared in step S4 is 120 - 180 mm;

[0023] Under the condition that the seepage pressure is 12.5 KPa, the permeability coefficient of the vertical cut-off wall material is 9.36×10 -9 ~7.95×10 -8 cm / s.

[0024] In summary, the present invention includes the following beneficial technical effects:

[0025] By using steel slag to replace part of the cement and optimizing the proportion of each component raw material, the present invention prepares a steel slag - cement - bentonite vertical cut-off wall material and applies it to a vertical anti-pollution barrier. The permeability coefficient and fluidity meet the requirements of the barrier wall, and the formed cut-off wall has excellent anti-seepage effect, and the permeability coefficient can reach 9.36×10 -9 cm / s; provides a standardized application plan for steel slag in anti-seepage projects, filling the industry gap. Description of the Drawings

[0026] Figure 1 is a diagram showing the change of the permeability coefficient of the vertical cut-off wall materials prepared in the curing examples 1 - 4 and comparative example 1 of the present invention at 7d, 14d, and 28d of curing.

[0027] Figure 2 is a diagram showing the change of the unconfined compressive strength of the vertical cut-off wall materials prepared in the curing examples 1 - 4 and comparative example 1 of the present invention at 7d, 14d, and 28d of curing. Detailed Embodiments

[0028] The present invention will be further described in detail below with reference to the embodiments and the drawings.

[0029] The steel slag, cement, and bentonite are all purchased commercially;

[0030] The steel slag is ground into granular particles with a particle size of 200 - 400 meshes. The steel slag includes dicalcium silicate, dicalcium ferrite, and RO phase. According to the formula P = CaO / (SiO2 + P2O5), the alkalinity of the steel slag is calculated, and the alkalinity of the steel slag is required to be 1.6 - 2.4;

[0031] The cement is 42.5 grade ordinary Portland cement, the specific surface area of the cement ≥ 300 m 2 / kg, the soundness is qualified, the 3d flexural strength ≥ 3.5 MPa, the 3d compressive strength ≥ 17 MPa, the initial setting time ≥ 45 min, the final setting time ≤ 600, the 28d flexural strength ≥ 6.5, and the 28d compressive strength ≥ 42.5;

[0032] The bentonite is a clay rock with a montmorillonite content of not less than 50%.

[0033] Example 1

[0034] A preparation method of a high-content steel slag-cement-bentonite vertical impervious wall material, comprising the following steps:

[0035] 1), Weigh 750 g of water and 140 g of bentonite respectively, and stir well until there are no particles to obtain bentonite slurry;

[0036] 2), Weigh 110 g of cement and 10 g of steel slag respectively and place them in the bentonite slurry prepared in step 1), stir well until there are no particles to obtain a mixed slurry;

[0037] 3), Prepare a mold, apply vaseline to the inner wall of the mold and set it aside. Pour the mixed slurry prepared in step 2) into the mold in three layers, and the height of each layer of the mixed slurry is the same. During the process of pouring each layer of the concrete slurry, it needs to be vibrated multiple times. After the mixed slurry is formed, demold it to obtain a specimen, and the specimen is a cylinder with a diameter of 3.91 cm and a height of 8 cm;

[0038] 4), Place the specimen prepared in step 3) in a curing box at a temperature of 18-22 °C and a relative humidity of 98% for curing to obtain the vertical impervious wall material.

[0039] Example 2

[0040] A preparation method of a high-content steel slag-cement-bentonite vertical impervious wall material, comprising the following steps:

[0041] 1), Weigh 750 g of water and 140 g of bentonite respectively, and stir well until there are no particles to obtain bentonite slurry;

[0042] 2), Weigh 105 g of cement and 15 g of steel slag respectively and place them in the bentonite slurry prepared in step 1), stir well until there are no particles to obtain a mixed slurry;

[0043] 3), Prepare a mold, apply vaseline to the inner wall of the mold and set it aside. Pour the mixed slurry prepared in step 2) into the mold in three layers, and the height of each layer of the mixed slurry is the same. During the process of pouring each layer of the concrete slurry, it needs to be vibrated multiple times. After the mixed slurry is formed, demold it to obtain a specimen, and the specimen is a cylinder with a diameter of 3.91 cm and a height of 8 cm;

[0044] 4), Place the specimen prepared in step 3) in a curing box at a temperature of 18-22 °C and a relative humidity of 98% for curing to obtain the vertical impervious wall material.

[0045] Example 3

[0046] A preparation method of a high-content steel slag-cement-bentonite vertical impervious wall material, comprising the following steps:

[0047] 1), Weigh 750 g of water and 140 g of bentonite respectively, stir well until there are no particles, and prepare bentonite slurry;

[0048] 2), Weigh 90 g of cement and 30 g of steel slag respectively and place them in the bentonite slurry prepared in step 1), stir well until there are no particles, and obtain mixed slurry;

[0049] 3), Prepare a mold, coat the inner wall of the mold with vaseline and set it aside. Pour the mixed slurry prepared in step 2) into the mold in three layers, with the same height for each layer of mixed slurry. During the pouring process of each layer of concrete slurry, it needs to be vibrated multiple times. After the mixed slurry is formed, demold it to obtain a specimen, and the specimen is a cylinder with a diameter of 3.91 cm and a height of 8 cm;

[0050] 4), Place the specimen prepared in step 3) in a curing box at a temperature of 18 - 22 °C and a relative humidity of 98% for curing to obtain vertical impervious wall materials.

[0051] Example 4

[0052] A preparation method of high - content steel slag - cement - bentonite vertical impervious wall materials, comprising the following steps:

[0053] 1), Weigh 750 g of water and 140 g of bentonite respectively, stir well until there are no particles, and prepare bentonite slurry;

[0054] 2), Weigh 60 g of cement and 60 g of steel slag respectively and place them in the bentonite slurry prepared in step 1), stir well until there are no particles, and obtain mixed slurry;

[0055] 3), Prepare a mold, coat the inner wall of the mold with vaseline and set it aside. Pour the mixed slurry prepared in step 2) into the mold in three layers, with the same height for each layer of mixed slurry. During the pouring process of each layer of concrete slurry, it needs to be vibrated multiple times. After the mixed slurry is formed, demold it to obtain a specimen, and the specimen is a cylinder with a diameter of 3.91 cm and a height of 8 cm;

[0056] 4), Place the specimen prepared in step 3) in a curing box at a temperature of 18 - 22 °C and a relative humidity of 98% for curing to obtain vertical impervious wall materials.

[0057] Comparative Example 1

[0058] A preparation method of vertical impervious wall materials, comprising the following steps:

[0059] 1), Weigh 750 g of water and 140 g of bentonite respectively, stir well until there are no particles, and prepare bentonite slurry;

[0060] 2), Weigh 120 g of cement and place it in the bentonite slurry prepared in step 1), and stir well until there are no particles to obtain a mixed slurry;

[0061] 3), Prepare a mold, apply vaseline to the inner wall of the mold and set it aside. Pour the mixed slurry prepared in step 2) into the mold in three layers, and the height of each layer of the mixed slurry is the same. During the process of pouring each layer of the concrete slurry, it needs to be vibrated multiple times. After the mixed slurry is formed, demold it to obtain a specimen, and the specimen is a cylinder with a diameter of 3.91 cm and a height of 8 cm;

[0062] 4), Place the specimen prepared in step 3) in a curing box at a temperature of 18 - 22 °C and a relative humidity of 98% for curing to obtain a vertical impervious wall material.

[0063] Performance Test

[0064] Test the permeability of the vertical impervious wall materials prepared in Examples 1 - 4 and Comparative Example 1 respectively, using the variable - head test method:

[0065]

[0066] In the formula, a is the cross - sectional area of the graduated tube (mm 2 ); L is the height of the soil sample (mm); A is the cross - sectional area of the soil sample (mm 2 ); t is the time difference (s).

[0067] The test results are shown in Table 1:

[0068]

[0069] Table 1 Permeability coefficient table of vertical impervious wall materials prepared in Examples 1 - 4 and Comparative Example 1

[0070] The average fluidity of the vertical impervious wall material prepared in Example 1 of this application meets 120 - 180 mm, the 7 - day permeability coefficient is 2.02×10 -6 cm / s, the 14 - day permeability coefficient is 9.91×10 -7 cm / s, and the 28 - day permeability coefficient is 7.95×10 -8 cm / s; The average fluidity of the vertical impervious wall material prepared in Example 2 of this application meets 120 - 180 mm, the 7 - day permeability coefficient is 1.51×10 -6 cm / s, the 14 - day permeability coefficient is 8.01×10 -7 cm / s, and the 28 - day permeability coefficient is 4.54×10 -8 cm / s; The average fluidity of the vertical impervious wall material prepared in Example 3 of this application meets 120 - 180 mm, the 7 - day permeability coefficient is 9.54×10 -7cm / s, the permeability coefficient at 14 days is 6.93×10 -7 cm / s, the permeability coefficient at 28 days is 3.90×10 -8 cm / s; the average fluidity of the vertical impervious wall material prepared in Example 4 of this application meets 120 - 180 mm, and the permeability coefficient at 28 days is 9.36×10 -9 cm / s; the permeability coefficient at 28 days of the vertical impervious wall material prepared in Comparative Example 1 of this application is 1.36×10 -7 cm / s.

[0071] Referring to Figure 1 , according to the data shown in Table 1, it can be known that when the ratio of cement to steel slag in this application is 1:1, the permeability coefficient at 28 days of the vertical impervious wall material reaches the optimal value of 9.36×10 -9 cm / s.

[0072] Referring to Figure 2 , as the amount of steel slag used increases, the compressive strength of the vertical impervious wall material will gradually decrease. Therefore, the vertical impervious wall material prepared in Example 2 of this application exhibits relatively balanced comprehensive performance.

[0073] The above are all preferred embodiments of the present invention, and the protection scope of the present invention is not limited accordingly. Therefore: Any equivalent changes made according to the structure, shape, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. High-volume steel slag-cement-bentonite vertical cutoff wall material, characterized in that, It includes the following raw materials: steel slag, cement, bentonite and water; Among them, the mass ratio of the sum of the masses of steel slag and cement to the mass of water is 1:(6-7); Bentonite accounts for 50-54% of the total mass of steel slag, cement and bentonite; The mass ratio of cement to steel slag is (1-11):

1.

2. The high-volume steel slag-cement-bentonite vertical impervious wall material according to claim 1, wherein The steel slag includes dicalcium silicate, dicalcium ferrite and RO phase.

3. The high-bleed slag-cement-bentonite vertical impervious wall material according to claim 2, characterized in that The basicity of the steel slag is 1.6-2.4; The particle size of the steel slag is 200-400 mesh.

4. The high-volume steel slag-cement-bentonite vertical impervious wall material according to claim 1 and its preparation method are characterized in that, The bentonite is a clay rock with a montmorillonite content of not less than 50%.

5. A preparation method of a high-content steel slag-cement-bentonite vertical impervious wall material according to any one of claims 1-4, characterized in that, It includes the following preparation method: S1. Weigh water and bentonite respectively, and stir well until there are no particles to obtain bentonite slurry; S2. Weigh cement and steel slag respectively and place them in the bentonite slurry prepared in step S1, and stir well until there are no particles to obtain a mixed slurry; S3. Prepare a mold, smear vaseline on the inner wall of the mold and set it aside. Pour the mixed slurry prepared in step S2 into the mold in three layers. After the mixed slurry is formed, demold it to obtain a specimen; S4. Place the specimen prepared in step S3 in a curing box for curing to obtain a vertical impervious wall material.

6. The high-content steel slag-cement-bentonite vertical impervious wall material according to claim 5 and its preparation method are characterized in that, In the three-layer mixed slurry in step S3, the height of each layer of mixed slurry is the same, and it needs to be vibrated many times during the pouring process of each layer of concrete slurry.

7. The high-dose steel slag-cement-bentonite vertical impervious wall material and its preparation method according to claim 5, characterized in that, In step S4, the temperature of the curing box is 18-22°C and the relative humidity is 98%.

8. The high-dose steel slag-cement-bentonite vertical impervious wall material and its preparation method according to claim 5, characterized in that, The fluidity of the vertical impervious wall material prepared in step S4 is 120-180mm; Under the condition that the seepage pressure is 12.5 KPa, the seepage coefficient of the vertical impervious wall material is 9.36×10 -9 ~7.95×10 -8 cm / s.

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