High-sludge-content high-fluidity filling material and preparation method thereof

Abstract

This invention discloses a high-fluidity backfill material with a large amount of slag and soil and its preparation method. By weight, it consists of the following components: 8-10 parts sulfate cement, 80-100 parts slag, 16-20 parts fly ash, 0.2-0.4 parts sodium tripolyphosphate, 0.4-0.5 parts sodium dodecane sulfate, 0.3-0.4 parts 2-ethylhexyl phosphate-2-ethylhexyl ester, 0.2-0.3 parts nano-sized air bubbles, 0.1-0.2 parts polyacrylamide, 0.6-0.9 parts calcium formate, and 12-18 parts water. This backfill material has good fluidity, achieving efficient and low-cost backfilling of goaf areas.

Description

Technical Field

[0001] This invention relates to the field of underground engineering, specifically to a high-fluidity backfill material with a large amount of slag and soil and its preparation method. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Karst areas account for nearly one-third of my country's land area, and underground mining subsidence areas cover as much as 1.349 million hectares. Major transportation infrastructure such as rail transit inevitably traverses karst and mining subsidence areas, making them highly susceptible to large-scale subsidence or collapse, becoming "bottlenecks" and "pain points" restricting the densification and extension of transportation networks. Especially for high-speed railways, even minor subsidence can seriously affect operational safety. Traditional backfill materials have poor fluidity and high costs, greatly impacting backfilling efficiency and quality. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a high-fluidity backfill material with a large amount of slag and soil and its preparation method, which can achieve low-cost, high-fluidity backfilling of subsurface goaf areas under infrastructure, thereby achieving efficient management of subsurface goaf areas under infrastructure.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0006] In a first aspect, the present invention provides a high-fluidity backfill material with a large amount of slag and soil, which, by mass, is composed of the following components: 8-10 parts sulfate cement, 80-100 parts slag and soil, 16-20 parts fly ash, 0.2-0.4 parts sodium tripolyphosphate, 0.4-0.5 parts sodium dodecane sulfate, 0.3-0.4 parts 2-ethylhexyl phosphate-2-ethylhexyl ester, 0.2-0.3 parts nano-sized air bubbles, 0.1-0.2 parts polyacrylamide, 0.6-0.9 parts calcium formate, and 12-18 parts water.

[0007] The functions of each component are as follows:

[0008] Sulfate cement: provides strength, increases the hardness and compressive strength of filling materials, and provides good coalescence and impermeability.

[0009] Construction waste: This refers to conventional construction waste. It serves as a supporting framework, improving the compressive strength of the materials.

[0010] Construction waste, often dumped and discarded indiscriminately, causes environmental pollution. Using construction waste as a major aggregate material can significantly reduce material costs through waste utilization. The use of fly ash, sodium tripolyphosphate, and sodium dodecane sulfate ensures high fluidity even with large amounts of fly ash added.

[0011] Fly ash: One of the sources of strength in materials, it can also improve the fluidity, cohesiveness and water retention of materials, making them easier to pump and mold.

[0012] Sodium tripolyphosphate: promotes the absorption of water in cement, improves the fluidity and ductility of cement, thereby enhancing the strength and toughness of the material; and improves the impermeability of the material.

[0013] Sodium dodecane sulfate: reduces the viscosity of materials, making them easier to work with and flow; increases the flexibility and plasticity of materials, thereby improving their crack resistance; promotes the early hydration reaction of mortar, allowing it to reach a hardening state more quickly.

[0014] 2-Ethylhexyl phosphate-2-ethylhexyl ester: It activates the activity of admixtures in the material, effectively improving the material's flowability and cohesiveness.

[0015] Nanoscale bubbles: improve material toughness; increase material compressive strength; reduce material porosity and improve material durability.

[0016] Polyacrylamide: It has water-retaining properties, making the material less prone to dispersion; it enhances the material's impermeability and bonding strength; it improves the material's tensile and bending resistance, durability, and flexural toughness.

[0017] Calcium formate: increases the early strength of materials, accelerates cement curing, and shortens setting time;

[0018] In some embodiments, the high-fluidity backfill material with large-volume slag and soil composition comprises, by weight, the following components: 8-10 parts sulfate cement, 85-95 parts slag and soil, 16-20 parts fly ash, 0.2-0.4 parts sodium tripolyphosphate, 0.4-0.5 parts sodium dodecane sulfate, 0.3-0.4 parts 2-ethylhexyl phosphate-2-ethylhexyl ester, 0.2-0.3 parts nano-sized air bubbles, 0.1-0.2 parts polyacrylamide, 0.6-0.9 parts calcium formate, and 12-16 parts water.

[0019] In some embodiments, the nanoscale bubbles are prepared by using a hydrocavitation method. When the airflow and water flow pass through the neck of a Venturi tube, the pressure changes rapidly due to the sharp decrease in tube diameter, causing the millimeter-sized bubbles to burst and collapse into micro- and nanoscale bubbles.

[0020] Preferably, the diameter of the nanoscale bubbles is less than 200 nm.

[0021] In some embodiments, the molecular weight of the polyacrylamide is 10 million to 18 million.

[0022] The viscosity of polyacrylamide solution increases with the increase of polymer molecular weight. A molecular weight of 10 million to 18 million can achieve the best effect required by the material and maximize the strength of the material.

[0023] In some embodiments, the specific surface area of ​​sulfoaluminate cement is 400–600 m². 2 / kg. The setting time of this cement with a water-cement ratio of 0.5 is 5 to 20 minutes.

[0024] In some embodiments, the particle size of the slag is 2mm-10mm.

[0025] Preferably, the particle size of the slag is 4mm-7mm.

[0026] Secondly, the present invention provides a method for preparing the high-volume, high-fluidity backfill material, comprising the following steps:

[0027] Grind and crush large particles;

[0028] Nanoscale bubble water was prepared by hydraulic cavitation.

[0029] After mixing the components evenly according to the preset mass ratio, the product is obtained.

[0030] In some embodiments, the solid powders are first mixed evenly and then mixed with nano-sized bubble water.

[0031] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0032] The filling material of this invention has good fluidity, enabling efficient and low-cost filling of goaf areas. Detailed Implementation

[0033] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0034] The present invention will be further described below with reference to the embodiments.

[0035] Example 1

[0036] A high-volume, high-fluidity backfill material for slag and soil is composed of the following components by weight: 10 parts sulfate cement, 80 parts slag and soil, 20 parts fly ash, 0.2 parts sodium tripolyphosphate, 0.4 parts sodium dodecyl sulfate, 0.3 parts 2-ethylhexyl phosphate-2-ethylhexyl ester, 0.3 parts nano-sized air bubbles, 0.1 parts polyacrylamide, 0.9 parts calcium formate, and 15 parts water.

[0037] The selected sulfoaluminate cement has a setting time of 10 minutes and a fly ash specific surface area of ​​500 m². 2 / kg, density 2.4g / cm³ 3 The average diameter of the nano-sized bubbles is 150 nm, and the molecular weight of the polyacrylamide is 15 million.

[0038] The components are mixed evenly in proportion to form a high-fluidity backfill material with a large amount of slag and soil.

[0039] According to NB / T 51070-2017 "Test Methods for Coal Mine Paste Backfilling Materials", the initial and final setting times, fluidity and uniaxial compressive strength of the backfilling materials were tested.

[0040] The slurry prepared according to the above proportions has an initial setting time of 6 hours, a final setting time of 12 hours, a slurry truncated cone flow distance of 18 cm, a 3-day compressive strength of 7.5 MPa, and a 28-day compressive strength of 10 MPa.

[0041] Example 2

[0042] A high-volume, high-fluidity backfill material for slag and soil is composed of the following components by weight: 10 parts sulfate cement, 80 parts slag and soil, 20 parts fly ash, 0.2 parts sodium tripolyphosphate, 0.3 parts nano-sized air bubbles, 0.1 parts polyacrylamide, 0.9 parts calcium formate, and 15 parts water.

[0043] The selected sulfoaluminate cement has a setting time of 10 minutes and a fly ash specific surface area of ​​500 m². 2 / kg, density 2.4g / cm³ 3 The nano-sized bubbles have a diameter of 150 nm, and the polyacrylamide has a molecular weight of 15 million.

[0044] The components are mixed evenly in proportion to form a high-fluidity backfill material with a large amount of slag and soil.

[0045] The slurry prepared according to the above proportions has an initial setting time of 6.5 h, a final setting time of 13 h, a slurry truncated cone flow distance of 17 cm, a 3-day compressive strength of 7 MPa, and a 28-day compressive strength of 9.5 MPa.

[0046] Example 3

[0047] A high-volume, high-fluidity backfill material for slag and soil is composed of the following components by weight: 10 parts sulfate cement, 80 parts slag and soil, 20 parts fly ash, 0.2 parts sodium tripolyphosphate, 0.4 parts sodium dodecyl sulfate, 0.3 parts 2-ethylhexyl phosphate-2-ethylhexyl ester, 0.3 parts nano-sized air bubbles, 0.1 parts polyacrylamide, and 15 parts water.

[0048] The selected sulfoaluminate cement has a setting time of 10 minutes and a fly ash specific surface area of ​​500 m².2 / kg, density 2.4g / cm³ 3 The nano-sized bubbles have a diameter of 150 nm, and the polyacrylamide has a molecular weight of 15 million.

[0049] The components are mixed evenly in proportion to form a high-fluidity backfill material with a large amount of slag and soil.

[0050] The slurry prepared according to the above proportions has an initial setting time of 6.5 h, a final setting time of 12 h, a slurry truncated cone flow distance of 17.5 cm, a 3-day compressive strength of 7.2 MPa, and a 28-day compressive strength of 9.8 MPa.

[0051] Comparative Example 1

[0052] The difference from Example 1 is that 2-ethylhexyl phosphate-2-ethylhexyl ester is omitted. Everything else is the same as in Example 1.

[0053] The prepared slurry had an initial setting time of 6.5 h, a final setting time of 13 h, a slurry truncated cone flow distance of 17 cm, a 3-day compressive strength of 7.4 MPa, and a 28-day compressive strength of 9.8 MPa.

[0054] Comparative Example 2

[0055] The difference from Example 1 is that the nanoscale bubbles are omitted. Everything else is the same as in Example 1.

[0056] The prepared slurry had an initial setting time of 6 hours, a final setting time of 12 hours, a slurry truncated cone flow distance of 18 cm, a 3-day compressive strength of 7 MPa, and a 28-day compressive strength of 9 MPa.

[0057] Comparative Example 3

[0058] The difference from Example 1 is that fly ash is omitted. Everything else is the same as in Example 1.

[0059] The prepared slurry had an initial setting time of 8 hours, a final setting time of 15 hours, a slurry truncated cone flow distance of 15 cm, a 3-day compressive strength of 5 MPa, and a 28-day compressive strength of 7 MPa.

[0060] Comparative Example 4

[0061] The difference from Example 1 is that sodium tripolyphosphate is omitted. Everything else is the same as in Example 1.

[0062] The prepared slurry had an initial setting time of 6.5 h, a final setting time of 13.5 h, a truncated cone flow distance of 16.5 cm, a 3-day compressive strength of 7.2 MPa, and a 28-day compressive strength of 9.5 MPa.

[0063] Comparative Example 5

[0064] The difference from Example 1 is that sodium dodecane sulfate is omitted. Everything else is the same as in Example 1.

[0065] The prepared slurry had an initial setting time of 6.6 h, a final setting time of 13.8 h, a truncated cone flow distance of 16.4 cm, a 3-day compressive strength of 7.3 MPa, and a 28-day compressive strength of 9.7 MPa.

[0066] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-volume, high-fluidity backfill material made from slag and soil, characterized in that: By weight, it consists of the following components: 8-10 parts sulfate cement, 80-100 parts slag, 16-20 parts fly ash, 0.2-0.4 parts sodium tripolyphosphate, 0.4-0.5 parts sodium dodecane sulfate, 0.3-0.4 parts 2-ethylhexyl phosphate-2-ethylhexyl ester, 0.2-0.3 parts nano-sized bubbles, 0.1-0.2 parts polyacrylamide, 0.6-0.9 parts calcium formate, and 12-18 parts water.

2. The high-volume, high-fluidity backfill material according to claim 1, characterized in that: By weight, it consists of the following components: 8-10 parts sulfate cement, 85-95 parts slag, 16-20 parts fly ash, 0.2-0.4 parts sodium tripolyphosphate, 0.4-0.5 parts sodium dodecane sulfate, 0.3-0.4 parts 2-ethylhexyl phosphate-2-ethylhexyl ester, 0.2-0.3 parts nano-sized bubbles, 0.1-0.2 parts polyacrylamide, 0.6-0.9 parts calcium formate, and 12-16 parts water.

3. The high-volume, high-fluidity backfill material according to claim 1, characterized in that: The method for preparing nanoscale bubbles is as follows: hydrocavitation.

4. The high-volume, high-fluidity backfill material with high admixture content of slag and soil according to claim 1, characterized in that: The diameter of nanoscale bubbles is less than 200 nm.

5. The high-volume, high-fluidity backfill material according to claim 1, characterized in that: Polyacrylamide has a molecular weight of 10 million to 18 million.

6. The high-volume, high-fluidity backfill material according to claim 1, characterized in that: Sulfoaluminate cement has a specific surface area of ​​400~600 m². 2 The setting time of this cement with a water-cement ratio of 0.5 and a density of 0.5 is 5~20min.

7. The high-volume, high-fluidity backfill material according to claim 1, characterized in that: The particle size of the slag is 2mm-10mm.

8. The high-volume, high-fluidity backfill material according to claim 1, characterized in that: The particle size of the slag is 4mm-7mm.

9. The preparation method of the high-volume, high-fluidity backfill material according to any one of claims 1-8, characterized in that: Includes the following steps: Grind and crush large particles; Nanoscale bubble water was prepared by hydraulic cavitation. After mixing the components evenly according to the preset mass ratio, the product is obtained.

10. The preparation method of the high-fluidity backfill material with large-volume slag and soil as described in claim 9, characterized in that: First, mix all the solid powders evenly, and then mix them with nano-sized bubble water.