A slow-release quick-setting agent for cement-based filling materials and its preparation method and application

Abstract

The present invention relates to the technical field of cement-based materials, and specifically to a slow-release quick-setting agent for cement-based filling materials, and a preparation method and application thereof. The slow-release quick-setting agent comprises: a calcium aluminate core and a cellulose primary shell layer coated on the surface of the core, and the surface of the primary shell layer is also coated with a nano-silicon dioxide secondary shell layer. After the slow-release quick-setting agent of the present invention is added to the filling glue solid powder-based filling material, the external primary shell layer and the secondary shell layer will be preferentially consumed during the pumping process, thereby protecting the calcium aluminate core of the quick-setting agent from being consumed during the pumping process, avoiding premature coagulation of the filling material, and causing problems such as pipe blockage.

Description

Technical Field

[0001] The invention relates to the technical field of cement-based materials, and in particular to a slow-release quick-setting agent for cement-based filling materials, and a preparation method and application thereof. Background Art

[0002] The backfill mining method has been widely used in the field of mining due to its environmental protection, safe mining operation, low ore loss rate and strong adaptability. During construction, pipeline pumping is generally used to transport the mine backfill glue powder formed by slag and cement clinker to the goaf. Mine backfill glue powder has the advantages of ultra-low carbon emissions, ultra-low energy consumption and low price. However, the early strength development of mine backfill glue powder is slow, so when mine backfill glue powder is used as a filling material in the goaf, there are problems such as too long support time, too late demoulding, increased construction time cycle and cost. Especially for filling projects that require shortened support time, the applicability of mine backfill glue powder is insufficient.

[0003] In order to overcome the above problems, the existing method is usually to add accelerating setting agent or early strength agent to the mine filling glue powder to adjust the setting time. However, the addition of accelerating setting agent or early strength agent will cause the mine filling glue powder to set prematurely during the pipeline pumping process, resulting in a series of problems such as pipe blockage, which increases the difficulty of pumping the filling material. In addition, the existing accelerating setting agent or early strength agent also has the problems of reducing the volume stability and durability of the filling material, making the setting time difficult to control, and the final strength is insufficient. Summary of the invention

[0004] In view of the above problems, the present invention provides a slow-release quick-setting agent for cement-based filling materials and a preparation method and application thereof, which effectively overcomes the problem of premature coagulation of filling glue powder during pumping and helps to improve the early mechanical strength of the filling material. Specifically, the present invention discloses the technical solution as shown below.

[0005] In a first aspect, the present invention provides a slow-release quick-setting agent for cement-based filling materials, comprising: a calcium aluminate core and a cellulose primary shell layer coated on the surface of the core, and the surface of the primary shell layer is also coated with a nano-silicon dioxide secondary shell layer.

[0006] Furthermore, the cellulose includes at least one of hydroxymethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, sodium carboxymethyl cellulose and the like.

[0007] Furthermore, the thickness of the primary shell is 30-50 nm, and the thickness of the secondary shell is 10-30 nm.

[0008] In a second aspect, the present invention provides a method for preparing a slow-release quick-setting agent for a cement-based filling material, comprising the following steps:

[0009] (1) Calcium aluminate powder and a saturated aqueous solution of cellulose are mixed and then ultrasonically treated, and then the obtained mixed solution is kept warm under heating conditions so that the cellulose coats the surface of the calcium aluminate particles. After completion, the solid product is separated, washed, and dried to obtain a primary core-shell structure in which the surface of the calcium aluminate core is coated with cellulose, which is then used for later use.

[0010] (2) The primary core-shell structure powder is placed in a chemical deposition reaction chamber, and then heated and stirred to make the powder flow, and then a solution formed by ethyl orthosilicate and a volatile solvent is heated to a gaseous state, and then the gaseous state is carried to the reaction chamber by a protective gas for reaction, and ammonia water is sprayed into the reaction chamber during the reaction. After the reaction is completed, the product is cooled to room temperature in the protective gas, and the product is washed and dried to obtain the slow-release quick-setting agent for cement-based filling materials.

[0011] Furthermore, in step (1), the ratio of the calcium aluminate powder to the cellulose solution is 1 g: 10-20 ml. Optionally, the fineness of the calcium aluminate powder is 50-80 mesh.

[0012] Furthermore, in step (1), the ultrasonic treatment time is 10-30 min, and the ultrasonic power is 200-300 W.

[0013] Furthermore, in step (1), the heating temperature is 40-60° C. and the insulation time is 15-25 min.

[0014] Furthermore, in step (1), the solid product is washed with at least one of anhydrous ethanol, clean water, etc. to remove the residues on the surface of the solid product.

[0015] Furthermore, in step (1), the drying temperature is 60-80° C. and the drying time is 6-10 hours.

[0016] Furthermore, in step (2), the heating temperature is 120-160°C.

[0017] Furthermore, in step (2), the ratio of the primary core-shell structure powder, tetraethyl orthosilicate and the solution formed by the volatile solvent is 1g:1-2.5ml. The mass ratio of tetraethyl orthosilicate to the volatile solvent is 1:2-5. Optionally, the volatile solvent includes any one of anhydrous methanol, anhydrous ethanol, acetone, toluene and the like.

[0018] Furthermore, in step (2), the gaseous substance is formed by heating to 160-200°C.

[0019] Furthermore, in step (2), the injection amount of the ammonia water is 1-3 ml / min. Optionally, the mass fraction of the ammonia water is 4-8%. The protective gas includes any one of nitrogen, argon, etc.

[0020] Furthermore, in step (2), the reaction time is 30 min to 2 h, and the pressure of the reaction chamber is set to 800 to 1000 Pa during the reaction. In this process, the tetraethyl orthosilicate (TEOS) is first hydrolyzed to generate silanol (Si(OC 2 H 5 ) 4 +4H 2 O→Si(OH) 4 + 4C 2 H 5 OH). Then the silicic acid undergoes polycondensation to form a silica network structure.

[0021] Furthermore, in step (2), the solid product is washed with at least one of anhydrous ethanol, clean water, anhydrous ether, acetone, etc. to remove the residual ethyl orthosilicate, etc. on the surface of the solid product.

[0022] Furthermore, in step (2), the drying temperature is 50-70° C. and the drying time is 8-10 hours.

[0023] In a third aspect, the present invention discloses the application of the slow-release quick-setting agent in cement-based filling materials of filling glue solid powder, wherein the application is: 400-600 parts by weight of filling glue solid powder, 800-1200 parts by weight of fly ash, 1400-2200 parts by weight of fine aggregate, 1000-1600 parts by weight of mixing water, and 1-3% of the slow-release quick-setting agent of the filling glue solid powder mass. In addition, an appropriate amount of admixtures such as a water reducer, a defoamer, etc. may be added as needed.

[0024] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0025] After the slow-release quick-setting agent of the present invention is added to the filling glue solid powder-based filling material, the primary shell layer and the secondary shell layer on the outside will be consumed preferentially during the pumping process, thereby protecting the calcium aluminate core of the quick-setting agent from being consumed during the pumping process, and avoiding premature coagulation of the filling material during the pumping stage, resulting in problems such as pipe blockage. When the filling material is pumped to the goaf, the quick-setting agent will play a role again, promoting the rapid coagulation of the filling material, effectively overcoming the contradiction that the addition of the quick-setting agent to the filling glue solid powder-based filling material is difficult to pump, and the lack of the accelerating coagulation agent leads to a slow coagulation rate, slow early strength development, and insufficient support force. This is because: first, the secondary shell layer formed by the nano-silicon dioxide on the quick-setting agent is adsorbed on the surface of the filling glue solid powder particles, and forms a protective film on the surface of the adsorbed clinker particles with the mixing water molecules, delaying the further contact between the particle surface and water, thereby delaying the hydration reaction rate of the filling glue solid powder, and achieving a temporary slow-setting effect. Secondly, the nano-silicon dioxide can also form hydrated calcium silicate gel with calcium hydroxide produced by the hydration of the filling glue solid powder, thereby forming a dense protective film on the surface of the filling glue solid powder particles. This protective film can not only prevent the particles from further contacting with the mixing water, but also hinder the diffusion and migration of the hydration products of the filling glue solid powder, thereby inhibiting the further hydration reaction of the filling glue solid powder, achieving the purpose of temporary retarding setting, and allowing the filling material to maintain good fluidity during the pumping process.

[0026] The cellulose adsorbed on the surface of the calcium aluminate particles forms a continuous coating / primary shell layer on the surface of the calcium aluminate particles due to the interaction between molecules, thereby effectively isolating the calcium aluminate accelerator from the external environment and preventing the accelerator from playing a role during the pumping process. In addition, during the pumping process, the cellulose can also use its long molecular chains to entangle with each other to form a network structure to wrap the mixing water in the filling material, preventing the mixing water from contacting the filling glue solid powder particles, hindering or slowing down its hydration rate, and allowing the filling glue solid powder to maintain good fluidity during the pumping process. After the pumping is completed, the hydroxyl (-OH) and other functional groups in the cellulose molecules react with the calcium ions (Ca 2+ ) complexation, gradually rendering the coating / primary shell formed by cellulose ineffective, allowing the calcium aluminate inside to play a coagulant role.

[0027] When the filling material is pumped to the goaf, the primary and secondary shells on the surface of the quick-setting agent are consumed, and the calcium aluminate core is released. It dissolves in the alkaline environment generated by the hydration of the filling glue powder, releasing calcium ions, aluminate ions and hydroxide ions, which accelerate the hydration reaction of the filling glue powder, so that it generates hydration products faster, and the cement stone structure is quickly formed, which prompts the filling material of the present invention to quickly solidify and harden, and improves the early mechanical properties. At the same time, the slow-release quick-setting agent of the present invention also helps to improve the later strength of the filling material and increase the toughness and durability of the filling material. This is because: (1) The nano-silicon dioxide has a high activity and specific surface area, and can react with the calcium hydroxide generated by the hydration of the filling glue powder to generate more hydrated calcium silicate gel. These additional gels are filled in the pores of the filling material, making the structure denser, thereby improving the later strength of the filling material. (2) The cellulose molecules form a three-dimensional network structure in the filling material to play a bridging and supporting role. When the filling material is subjected to external force, the mesh structure can absorb and dissipate energy, prevent the expansion and extension of cracks, and thus enhance the toughness of the filling material. (3) The water-retaining effect of the cellulose slows down the water loss of the filling material during the drying process, reducing shrinkage cracks caused by rapid evaporation of water. At the same time, the mesh structure formed by the cellulose and the wrapping effect on the filling glue solid powder particles improve the compactness of the filling material, reduce the intrusion of external harmful media, enhance the impermeability and erosion resistance of the filling material, and thus improve the durability of the filling material. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 The transmission electron microscope (TEM) image of the primary core-shell structure prepared in Example 1 below.

[0030] Figure 2 This is a sample picture of the slow-release quick-setting agent prepared in the following Example 1.

[0031] Figure 3 The following is a scanning electron microscope (SEM) image of the slow-release quick-setting agent prepared in Example 1.

[0032] Figure 4 The XRD pattern of the slow-release quick-setting agent prepared in Example 1 below.

[0033] Figure 5 The following is a transmission electron microscope (TEM) image of the slow-release quick-setting agent prepared in Example 1.

[0034] Figure 6The following is a compressive strength test diagram of Example 1.

[0035] Figure 7 The following is a graph showing the flexural strength test of Example 1.

[0036] Figure 8 This is a graph showing the setting time test of Example 1 below.

[0037] Fig. 9 This is a compressive strength test diagram of the following Example 2.

[0038] Fig.10 This is a flexural strength test diagram of the following Example 2. DETAILED DESCRIPTION

[0039] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0040] Unless otherwise defined, all professional and scientific terms used in the present invention have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. If there are no special instructions, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar to or equivalent to the described content can be applied to the method of the present invention. Now, the technical solution of the present invention is further described in conjunction with the accompanying drawings and specific embodiments of the specification.

[0041] Example 1

[0042] A method for preparing a slow-release quick-setting agent for cement-based filling materials comprises the following steps:

[0043] (1) Mix calcium aluminate powder with a fineness of 60 mesh and a saturated aqueous solution of hydroxymethyl cellulose in a ratio of 1g:15ml, stir magnetically and evenly, then ultrasonically treat for 20 minutes at an ultrasonic power of 300W. Then heat the obtained mixed solution to 40°C and keep it warm for 20 minutes. After completion, transfer the obtained reaction solution to a centrifuge tube, and then centrifuge it at a speed of 3500r / min for 8 minutes. After completion, discard the supernatant. Wash the obtained solid product three times with anhydrous ethanol, and then vacuum dry it at 70°C for 8 hours to obtain a primary core-shell structure with cellulose coated on the surface of the calcium aluminate core. The TEM test results are shown as follows: Figure 1 As shown, it can be seen that the structure has core-shell characteristics.

[0044] (4) The primary core-shell structure powder is placed in a chemical deposition reaction chamber, and then heated to 150°C and stirred to make the powder flow. Then, the ethyl orthosilicate solution (mixed by ethyl orthosilicate and anhydrous ethanol in a mass ratio of 1:5) is heated to 180°C to become a gaseous substance, and the gaseous substance is carried to the reaction chamber by nitrogen for reaction. The ratio of the primary core-shell structure powder to the ethyl orthosilicate solution is 1g:1.5ml. At the same time, during the reaction, ammonia water with a mass fraction of 7% is sprayed into the reaction chamber (the spraying amount is 2ml / min), and the pressure of the reaction chamber is set to 1000Pa. After reacting for 30 minutes, it is cooled to room temperature in the nitrogen atmosphere, and the product is washed with anhydrous ethanol and heated to 60°C and dried for 8 hours to obtain the slow-release quick-setting agent for cement-based filling materials. The physical sample picture, SEM, XRD, and TEM test results are shown as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 As shown, from Figure 5 It can be seen that the slow-release quick-setting agent has a core-shell structure, the thickness of its primary shell is about 30-50 nm, and the thickness of its secondary shell is about 10-30 nm.

[0045] Performance test: The cement-based filling material is prepared in the following proportions, including the following components: 500 parts by weight of filling mortar powder (65 wt.%, 15 wt.%, clinker, 18 wt.%, sodium carbonate, the same as in other embodiments), 1000 parts by weight of fly ash, 1750 parts by weight of river sand fine aggregate, 1300 parts by weight of mixing water, and then 7.5 parts by weight of the slow-release quick-setting agent prepared in this embodiment are added. The above components are mixed and stirred evenly to obtain a cement-based filling material. Then, the 3d compressive strength of the cement-based filling material is tested according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GBT 17671-2021) (such as Figure 6 as shown) and 3d flexural strength (as shown Figure 7 As shown in FIG. 1 ), a Vicat apparatus is used to test the setting time of the cement-based filling material (as shown in FIG. Figure 8 The test results are shown in the following table:

[0046] .

[0047] Example 2

[0048] A method for preparing a slow-release quick-setting agent for cement-based filling materials comprises the following steps:

[0049] (1) Mix calcium aluminate powder with a fineness of 80 mesh and a saturated aqueous solution of hydroxyethyl methyl cellulose in a ratio of 1g:10ml, stir magnetically and evenly, then ultrasonically treat for 30 minutes at an ultrasonic power of 200W. Then heat the obtained mixed solution to 50°C and keep it warm for 25 minutes. After completion, transfer the obtained reaction solution to a centrifuge tube, and then centrifuge it at a speed of 3500r / min for 8 minutes. After completion, discard the supernatant. Wash the obtained solid product three times with anhydrous ethanol, and then vacuum dry it at 60°C for 10 hours to obtain a primary core-shell structure with cellulose coated on the surface of the calcium aluminate core, which is set aside.

[0050] (2) The primary core-shell structure powder is placed in a chemical deposition reaction chamber, and then heated to 120°C and stirred to make the powder flow, and then the ethyl orthosilicate solution (mixed by ethyl orthosilicate and toluene in a mass ratio of 1:3) is heated to 160°C to become a gas, and the gas is carried to the reaction chamber by nitrogen for reaction. The ratio of the primary core-shell structure powder to the ethyl orthosilicate solution is 1g:1ml. At the same time, during the reaction, ammonia water with a mass fraction of 8% (the injection amount is 1ml / min) is sprayed into the reaction chamber, and the pressure of the reaction chamber is set to 800Pa. After reacting for 1h, it is cooled to room temperature in the nitrogen atmosphere, and the product is washed with anhydrous ethanol and heated to 50°C and dried for 10 hours to obtain the slow-release quick-setting agent for cement-based filling materials.

[0051] Performance test: The cement-based filling material is prepared according to the following proportions, including the following proportions: 400 parts by weight of filling mortar powder, 800 parts by weight of fly ash, 1400 parts by weight of river sand fine aggregate, 0.8 parts by weight of polycarboxylic acid water reducer, 1000 parts by weight of mixing water, and then 6 parts by weight of the slow-release quick-setting agent prepared in this embodiment are added. The above components are mixed and stirred evenly to obtain a cement-based filling material. Then, the 3d compressive strength of the cement-based filling material is tested according to the "Test Method for Cement Mortar Strength (ISO Method)" (GBT 17671-2021) (such as Fig. 9 As shown), 3d flexural strength (as shown Fig.10 As shown), the setting time of the cement-based filling material is tested using a Vicat instrument, and the test results are shown in the following table:

[0052] .

[0053] Example 3

[0054] A method for preparing a slow-release quick-setting agent for cement-based filling materials comprises the following steps:

[0055] (1) Mix 50-mesh calcium aluminate powder and a saturated aqueous solution of propyl methyl cellulose in a ratio of 1g:20ml, stir magnetically and evenly, then ultrasonically treat for 10 minutes at an ultrasonic power of 250W. Then heat the obtained mixed solution to 60°C and keep it warm for 15 minutes. After completion, transfer the obtained reaction solution to a centrifuge tube, and then centrifuge it at a speed of 3500r / min for 8 minutes. After completion, discard the supernatant. Wash the obtained solid product three times with anhydrous ethanol, and then vacuum dry it at 80°C for 6 hours to obtain a primary core-shell structure with cellulose coated on the surface of the calcium aluminate core, which is set aside.

[0056] (2) The primary core-shell structure powder is placed in a chemical deposition reaction chamber, and then heated to 160°C and stirred to make the powder flow, and then the ethyl orthosilicate solution (mixed by ethyl orthosilicate and acetone in a mass ratio of 1:2) is heated to 200°C to become a gas, and the gas is carried to the reaction chamber by nitrogen for reaction. The ratio of the primary core-shell structure powder to the ethyl orthosilicate solution is 1g:2.5ml. At the same time, during the reaction, ammonia water with a mass fraction of 4% is sprayed into the reaction chamber (the spraying amount is 3ml / min), and the pressure of the reaction chamber is set to 800Pa. After reacting for 2h, it is cooled to room temperature in the nitrogen atmosphere, the product is washed with distilled water, heated to 70°C and dried for 8 hours, and the slow-release quick-setting agent for cement-based filling materials is obtained.

[0057] Performance test: The cement-based filling material is prepared according to the following proportions, including the following components: 600 parts by weight of filling mortar powder, 1200 parts by weight of fly ash, 2200 parts by weight of river sand fine aggregate, 1.2 parts by weight of polycarboxylic acid water-reducing agent, 1600 parts by weight of mixing water, and then 16 parts by weight of the slow-release quick-setting agent prepared in this embodiment are added. The above components are mixed and stirred evenly to obtain a cement-based filling material. Then, according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GBT 17671-2021), the 3d compressive strength and 3d flexural strength of the cement-based filling material are tested, and the setting time of the cement-based filling material is tested using a Vicat instrument. The test results are shown in the following table:

[0058] .

[0059] Example 4

[0060] A method for preparing a slow-release quick-setting agent for cement-based filling materials comprises the following steps:

[0061] (1) Mix calcium aluminate powder with a fineness of 60 mesh and a saturated aqueous solution of hydroxymethyl cellulose in a ratio of 1g:18ml, stir magnetically and evenly, then ultrasonically treat for 15 minutes at an ultrasonic power of 200W. Then heat the obtained mixed solution to 45°C and keep it warm for 20 minutes. After completion, transfer the obtained reaction solution to a centrifuge tube, and then centrifuge it at a speed of 3500r / min for 8 minutes. After completion, discard the supernatant. Wash the obtained solid product three times with anhydrous ethanol, and then vacuum dry it at 60°C for 9 hours to obtain a primary core-shell structure with cellulose coated on the surface of the calcium aluminate core, which is set aside.

[0062] (2) The primary core-shell structure powder is placed in a chemical deposition reaction chamber, and then heated to 150°C and stirred to make the powder flow, and then the ethyl orthosilicate solution (mixed by ethyl orthosilicate and anhydrous methanol in a mass ratio of 1:3) is heated to 170°C to become a gaseous substance, and the gaseous substance is carried to the reaction chamber by nitrogen for reaction. The ratio of the primary core-shell structure powder to the ethyl orthosilicate solution is 1g:2ml. At the same time, during the reaction, ammonia water with a mass fraction of 7% is sprayed into the reaction chamber (the spraying amount is 1ml / min), and the pressure of the reaction chamber is set to 1000Pa. After reacting for 1h, it is cooled to room temperature in the nitrogen atmosphere, and the product is washed with acetone and heated to 70°C and dried for 8 hours to obtain the slow-release quick-setting agent for cement-based filling materials.

[0063] Performance test: The cement-based filling material is prepared according to the following proportions, including the following proportions of components: 520 parts by weight of filling mortar powder, 1100 parts by weight of fly ash, 2000 parts by weight of river sand fine aggregate, and 1450 parts by weight of mixing water, and then 22.5 parts by weight of the slow-release quick-setting agent prepared in this embodiment are added. The above components are mixed and stirred evenly to obtain a cement-based filling material. Then, according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GBT 17671-2021), the 3d compressive strength and 3d flexural strength of the cement-based filling material are tested, and the setting time of the cement-based filling material is tested using a Vicat instrument. The test results are shown in the following table:

[0064] .

[0065] Example 5

[0066] The cement-based filling material is prepared according to the following proportions, including the following proportions of components: 500 parts by weight of filling mortar powder, 1000 parts by weight of fly ash, 1750 parts by weight of river sand fine aggregate, 1300 parts by weight of mixing water, and then 7.5 parts by weight of calcium aluminate powder with a fineness of 60 mesh is added. The above components are mixed and stirred evenly to obtain a cement-based filling material. Then, according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GBT 17671-2021), the 3d compressive strength and 3d flexural strength of the cement-based filling material are tested, and the setting time of the cement-based filling material is tested using a Vicat instrument. The test results are shown in the following table:

[0067] .

[0068] Example 6

[0069] The cement-based filling material is prepared according to the following proportions, including the following proportions of components: 500 parts by weight of filling mortar powder, 1000 parts by weight of fly ash, 1750 parts by weight of river sand fine aggregate, and 1300 parts by weight of mixing water, and then 7.5 parts by weight of the primary core-shell structure prepared in step (1) of the above-mentioned Example 1 are added. The above-mentioned components are mixed and stirred evenly to obtain a cement-based filling material. Then, according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GBT 17671-2021), the 3d compressive strength and 3d flexural strength of the cement-based filling material are tested, and the setting time of the cement-based filling material is tested using a Vicat instrument. The test results are shown in the following table:

[0070] .

[0071] Example 7

[0072] A method for preparing a slow-release quick-setting agent for cement-based filling materials comprises the following steps:

[0073] The primary core-shell structure powder (prepared in the same manner as in Example 2) is placed in a chemical deposition reaction chamber, then heated to 120°C and stirred to make the powder flow, and then the ethyl orthosilicate solution (mixed by ethyl orthosilicate and toluene in a mass ratio of 1:3) is heated to 160°C to form a gaseous substance, and the gaseous substance is carried to the reaction chamber by nitrogen for reaction, the ratio of the primary core-shell structure powder to the ethyl orthosilicate solution is 1g:1 ml, and the pressure of the reaction chamber is set to 800Pa. After reacting for 1h, it is cooled to room temperature in the nitrogen, the product is washed with anhydrous ethanol, heated to 50°C and dried for 10 hours, and the slow-release quick-setting agent for cement-based filling materials is obtained.

[0074] Performance test: The cement-based filling material is prepared according to the following proportions, including the following proportions of components: 400 parts by weight of filling mortar powder, 800 parts by weight of fly ash, 1400 parts by weight of river sand fine aggregate, 0.8 parts by weight of polycarboxylic acid water-reducing agent, 1000 parts by weight of mixing water, and then 6 parts by weight of the slow-release quick-setting agent prepared in this embodiment are added. The above components are mixed and stirred evenly to obtain a cement-based filling material. Then, according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GBT 17671-2021), the 3d compressive strength and 3d flexural strength of the cement-based filling material are tested, and the setting time of the cement-based filling material is tested using a Vicat instrument. The test results are shown in the following table:

[0075] .

[0076] Example 8

[0077] The cement-based filling material is prepared according to the following proportions, including the following proportions of components: 600 parts by weight of filling mortar powder, 1200 parts by weight of fly ash, 2200 parts by weight of river sand fine aggregate, 1.2 parts by weight of polycarboxylic acid water reducer, and 1600 parts by weight of mixing water. The above components are mixed and stirred evenly to obtain a cement-based filling material. Then, according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GBT 17671-2021), the 3d compressive strength and 3d flexural strength of the cement-based filling material are tested, and the setting time of the cement-based filling material is tested using a Vicat instrument. The test results are shown in the following table:

[0078] .

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A slow-release quick-setting agent for cement-based filling materials, characterized in that: include: A calcium aluminate core and a cellulose primary shell layer coated on the surface of the core, and the surface of the primary shell layer is also coated with a nano silicon dioxide secondary shell layer; The cellulose includes at least one of hydroxymethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose and sodium carboxymethyl cellulose.

2. The slow-release quick-setting agent for cement-based filling materials according to claim 1, characterized in that: The thickness of the primary shell is 30-50 nm.

3. The slow-release quick-setting agent for cement-based filling materials according to claim 1, characterized in that: The thickness of the secondary shell is 10-30 nm.

4. A method for preparing a slow-release quick-setting agent for cement-based filling materials, characterized in that: The steps include: (1) mixing calcium aluminate powder and a saturated aqueous solution of cellulose and then subjecting the mixture to ultrasonic treatment, and then subjecting the obtained mixed solution to heat preservation treatment under heating conditions, so that the cellulose coats the surface of the calcium aluminate particles; after completion, separating the solid product, washing and drying, obtaining a primary core-shell structure in which the surface of the calcium aluminate core is coated with cellulose, and setting aside; (2) placing the primary core-shell structure powder in a chemical deposition reaction chamber, and then heating and stirring to make the powder flow; then heating a solution formed by ethyl orthosilicate and a volatile solvent into a gaseous substance, and then using a protective gas to carry the gaseous substance into the reaction chamber for reaction, and spraying ammonia water into the reaction chamber during the reaction; after the reaction is completed, cooling to room temperature in the protective gas, washing the product and drying it, thereby obtaining the slow-release quick-setting agent for cement-based filling materials.

5. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (1), the ratio of calcium aluminate powder to cellulose solution is 1 g: 10-20 ml.

6. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (1), the fineness of the calcium aluminate powder is 50-80 mesh.

7. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (1), the ultrasonic treatment time is 10-30 min, and the ultrasonic power is 200-300 W.

8. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (1), the heating temperature is 40-60° C. and the insulation time is 15-25 min.

9. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (1), the solid product is washed with at least one of anhydrous ethanol and clean water.

10. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (1), the drying temperature is 60-80°C and the drying time is 6-10 hours.

11. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (2), the heating temperature is 120-160°C.

12. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (2), the ratio of the primary core-shell structure powder, tetraethyl orthosilicate and the solution formed by the volatile solvent is 1 g: 1-2.5 ml.

13. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (2), the mass ratio of the tetraethyl orthosilicate to the volatile solvent is 1:2-5.

14. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (2), the volatile solvent includes any one of anhydrous methanol, anhydrous ethanol, acetone, and toluene.

15. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to claim 4, characterized in that: In step (2), the gaseous substance is formed by heating to 160-200°C.

16. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to any one of claims 4 to 15, characterized in that: In step (2), the injection rate of the ammonia water is 1-3 ml / min.

17. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to any one of claims 4 to 15, characterized in that: In step (2), the mass fraction of the ammonia water is 4-8%.

18. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to any one of claims 4 to 15, characterized in that: In step (2), the protective gas includes any one of nitrogen and argon.

19. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to any one of claims 4 to 15, characterized in that: In step (2), the reaction time is 30 min to 2 h, and the pressure of the reaction chamber is set to 800 to 1000 Pa during the reaction.

20. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to any one of claims 4 to 15, characterized in that: In step (2), the solid product is washed with at least one of anhydrous ethanol, clean water, anhydrous ether and acetone.

21. The method for preparing a slow-release quick-setting agent for cement-based filling materials according to any one of claims 4 to 15, characterized in that: In step (2), the drying temperature is 50-70° C. and the drying time is 8-10 hours.

22. Use of the slow-release quick-setting agent for cement-based filling materials according to any one of claims 1 to 3 or the slow-release quick-setting agent obtained by the preparation method according to any one of claims 4 to 21 in filling glue solid powder-based filling materials; the filling glue solid powder-based filling materials are: 400-600 parts by weight of filling glue solid powder, 800-1200 parts by weight of fly ash, 1400-2200 parts by weight of fine aggregate, 1000-1600 parts by weight of mixing water, and 1-3% of the mass of the slow-release quick-setting agent of the filling glue solid powder.

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