Cement-based high-water-content grouting material with high service performance and preparation method of cement-based high-water-content grouting material

Abstract

The invention discloses a cement-based high-water-content grouting material with high service performance and a preparation method thereof. The grouting material comprises a base material and an additive, the base material comprises a gelling material, a retarder, a water reducing agent, an alkali activator, a coagulant and water, the gelling agent comprises cement, anhydrous gypsum powder and quicklime powder, and the additive comprises graphene oxide, polyoxyethylene and fumed silica. While the compressive strength of an original material is met, the service performance of the material is remarkably improved, and the utilization rate of the grouting material under complex geological conditions such as a coal mine well is increased, so that the construction defects of the sulphoaluminate cement-based high-water grouting material under the complex geological conditions are reduced, the environmental pollution is reduced, and green mining of a coal mine is realized; the method has important value for popularizing the engineering application of the sulphoaluminate cement-based high-water-content grouting material.

Description

Technical Field

[0001] The present invention belongs to the technical field of grouting materials, and particularly relates to a cement-based high-water grouting material with strong serviceability and a preparation method thereof. Background Art

[0002] The grouting reinforcement technology is a technology that injects liquid or paste materials into cracks, pores or holes in rock and soil masses, and after curing, forms a filling body with certain strength and stability, so as to achieve the purpose of reinforcing and preventing seepage of surrounding rocks. In the support of surrounding rocks in coal mine roadways, the grouting reinforcement technology is widely used to treat problems such as loosening of surrounding rocks, development of cracks and groundwater seepage. However, the performance of the grouting material directly affects the grouting effect, so the research on grouting materials is crucial.

[0003] Sulfoaluminate cement is a new type of cement invented by the China Building Materials Academy of Sciences in 1972, and has the advantages of rapid hardening and early strength, low alkalinity, corrosion resistance and low temperature adaptability. However, the complex environmental conditions in coal mines, especially the characteristics of high air humidity and good ventilation performance, pose challenges to the performance of sulfoaluminate cement-based high-water grouting materials:

[0004] (1) High humidity environment: The air humidity in the mine is usually high, which may cause the grouting material to absorb too much water, affecting its curing process and final mechanical properties.

[0005] (2) Good ventilation: Good ventilation although helps to improve the working environment, but may also accelerate the evaporation of surface water of the material, resulting in dry shrinkage cracks on the material surface.

[0006] (3) Long-term durability problems: There may be certain chemical corrosion media in the mine environment (such as sulfate ions in mine water), which pose a threat to the long-term stability of the grouting material.

[0007] To improve the macroscopic mechanical properties and service durability of sulfoaluminate cement-based high-water grouting materials, the following optimization measures can be taken:

[0008] (1) Modification treatment

[0009] Add appropriate mineral admixtures (such as fly ash, silica fume, etc.) or fiber materials (such as polypropylene fiber, steel fiber, etc.) to the material to improve its microstructure and mechanical properties. Use functional admixtures (such as waterproof agents, preservatives, etc.) to enhance the impermeability and corrosion resistance of the material.

[0010] (2) Adjust the proportion

[0011] According to the specific engineering requirements, optimize the ratio of sulfoaluminate cement to water, and reasonably select the type and dosage of admixtures. Develop special formulas suitable for different humidity conditions to improve the adaptability of the material.

[0012] (3) Improve the construction technology

[0013] Adopt advanced grouting equipment and technology, control the grouting pressure and speed to ensure that the materials can fill the target area evenly and sufficiently.

[0014] Although there are many optimization measures for grouting materials, the most fundamental method is to change the composition of the grouting materials. At present, the method of designing the composition of grouting materials can partially improve their mechanical properties. However, in the face of the complex environmental conditions in coal mines, the mechanical properties decrease significantly over time. How to improve the serviceability and durability of grouting materials is the focus of this invention. Summary of the Invention

[0015] The purpose of this invention is to provide a cement-based high-water grouting material with strong serviceability and its preparation method to solve the problem of poor durability of the above-mentioned grouting materials.

[0016] To achieve the above purpose, in the first aspect of this invention, a cement-based high-water grouting material with strong serviceability is provided. The grouting material includes a base material and an admixture.

[0017] The base material, by weight, includes the following raw materials:

[0018]

[0019] The admixture, by volume fraction of the base material, includes the following raw materials:

[0020] Graphene oxide 0.01% - 0.05%;

[0021] Polyethylene oxide 0.05% - 0.09%;

[0022] Fumed silica 0.05% - 0.09%.

[0023] The admixture in this invention includes graphene oxide, polyethylene oxide and fumed silica. By utilizing the large specific surface area and bridging blocking effect provided by graphene oxide, polyethylene oxide and fumed silica at the microscopic level, the hydration reaction process of the system is promoted, thereby improving the mechanical properties and durability of the grouting material.

[0024] Preferably, the cementitious material, by weight, includes the following raw materials:

[0025] Cement 450 - 550 parts;

[0026] Anhydrous gypsum powder 350 - 450 parts;

[0027] Quicklime powder 50 - 150 parts.

[0028] Preferably, the cement is sulfoaluminate cement, and the Al 2 O 3 content is 29.54%; the SO 3 content in the anhydrous gypsum powder is 40.1%; the CaO content in the quicklime powder is 79.81%.

[0029] Preferably, the retarder is anhydrous citric acid with a purity of 99%.

[0030] Preferably, the water reducer is a naphthalene-based superplasticizer with a water reduction rate of 15%.

[0031] Preferably, the alkali activator is anhydrous sodium carbonate with a purity of 99%.

[0032] Preferably, the coagulant is lithium carbonate with a purity of 99%.

[0033] Preferably, the water-cement ratio of the grouting material is 1:1, and the compressive strength of the grouting material after 14 days of curing is 18 - 21 MPa.

[0034] The second aspect of the present invention provides a preparation method of a cement-based high-water grouting material with strong serviceability, including the following steps:

[0035] a) Add the retarder, water reducer, alkali activator, graphene oxide, polyethylene oxide, and fumed silica into the cement, and stir at a low speed for 100 - 150 s to make material A;

[0036] b) Mix the quicklime powder and anhydrous gypsum powder, then add the coagulant, and stir at a low speed for 100 - 150 s to make material B;

[0037] c) Add water to material A and material B respectively, stir at a low speed for 100 - 150 s, stir at a high speed for 30 - 90 s, and finally mix material A and material B, stir at a high speed for 60 - 120 s. After stirring is completed, a slurry is obtained;

[0038] d) Pour the mixed slurry into the corresponding test mold, let it stand for initial setting, then remove the mold and place it in a curing room for curing until 28 days.

[0039] Preferably, the speed of low-speed stirring is 30 - 60 revolutions per minute, and the speed of high-speed stirring is 120 - 150 revolutions per minute.

[0040] The third aspect of the present invention provides an application of a cement-based high-water grouting material with strong serviceability in the support of surrounding rock in coal mine roadways.

[0041] Therefore, the present invention adopts a cement-based high-water grouting material with strong serviceability and its preparation method with the above structure, and has the following beneficial effects:

[0042] (1) The present invention promotes the hydration reaction process in the cement system by adding admixtures, further enhancing the original mechanical properties and service performance of the raw materials.

[0043] (2) The present invention uses graphene oxide, polyethylene oxide, and fumed silica to prepare a sulfoaluminate cement-based high-water grouting material, achieving an improvement in the service performance of the material and solving the problem of the influence of underground geological conditions on the service performance of the material.

[0044] (3) The method for preparing the sulfoaluminate cement-based high-water grouting material of the present invention produces a grouting material with excellent mechanical properties, durability, and even more excellent workability. The grouting material also has good fluidity, which can fully meet the underground construction conditions and achieve no pipe blockage, no liquid leakage, few internal pores, and small pore diameters.

[0045] The following is a further detailed description of the technical solution of the present invention through examples. Specific Embodiments

[0046] The following will further describe the present invention. It should be noted that this embodiment is based on the present technical solution, and detailed implementation methods and specific operation processes are given, but the present invention is not limited to this embodiment.

[0047] The parameters and sources of graphene oxide, polyethylene oxide, and fumed silica used in the examples are as follows:

[0048] Graphene oxide (GO) was purchased from Suzhou Carbon Feng Graphene Technology Co., Ltd., and its appearance is black-brown powder. The main performance parameters of GO are listed in Table 1.

[0049] Table 1 GO Performance Parameters

[0050]

[0051] Polyethylene oxide (PEO) was purchased from Hefei Tissue Culture Biotechnology Co., Ltd., and its appearance is white granular powder. The main performance parameters of PEO are listed in Table 2.

[0052] Table 2 PEO Performance Parameters

[0053]

[0054] Fumed silica (G) was purchased from Shandong Yousuo Chemical Technology Co., Ltd. It is a fine and special amorphous powder material prepared by high-temperature hydrolysis of chlorosilane with a hydrogen-oxygen flame. G has two types: hydrophilic and hydrophobic. The hydrophilic type was selected for this experiment. The main performance parameters of G are listed in Table 3.

[0055] Table 3 G Performance Parameters

[0056]

[0057] Example 1

[0058] A cement-based high-water grouting material with strong serviceability. The grouting material includes a base material and an admixture;

[0059] The base material, by weight parts, includes the following raw materials:

[0060]

[0061] The admixture, by volume fraction of the base material, includes the following raw materials:

[0062] Graphene oxide 0.05%;

[0063] Polyethylene oxide 0.05%;

[0064] Fumed silica 0.05%.

[0065] Example 2

[0066] A cement-based high-water grouting material with strong serviceability. The grouting material includes a base material and an admixture; The base material, by weight parts, includes the following raw materials:

[0067]

[0068] The admixture, by volume fraction of the base material, includes the following raw materials:

[0069] Graphene oxide 0.15%;

[0070] Polyethylene oxide 0.15%;

[0071] Fumed silica 0.15%.

[0072] Example 3

[0073] A cement-based high-water grouting material with strong serviceability. The grouting material includes a base material and an admixture; The base material, by weight parts, includes the following raw materials:

[0074]

[0075]

[0076] The admixture, by volume fraction of the base material, includes the following raw materials:

[0077] Graphene oxide 0.25%;

[0078] Polyethylene oxide 0.25%;

[0079] Fumed silica 0.25%.

[0080] Example 4

[0081] A cement-based high-water grouting material with strong serviceability, the grouting material comprising a base material and an admixture; the base material, by weight parts, comprises the following raw materials:

[0082]

[0083] The admixture, by volume fraction of the base material, comprises the following raw materials:

[0084] Graphene oxide 0.35%;

[0085] Polyethylene oxide 0.35%;

[0086] Fumed silica 0.35%.

[0087] Example 5

[0088] A cement-based high-water grouting material with strong serviceability, the grouting material comprising a base material and an admixture;

[0089] The base material, by weight parts, comprises the following raw materials:

[0090]

[0091] The admixture, by volume fraction of the base material, comprises the following raw materials:

[0092] Graphene oxide 0.45%;

[0093] Polyethylene oxide 0.45%;

[0094] Fumed silica 0.45%.

[0095] The preparation method of the grouting materials of Examples 1 to 5 is as follows:

[0096] Specifically, it comprises the following steps:

[0097] a) Add the retarder, water reducer, alkali activator, graphene oxide, polyethylene oxide, and fumed silica into the cement, and stir at a high speed of 130 revolutions per minute for 120 s to prepare Material A;

[0098] b) Mix the quicklime powder and anhydrous gypsum powder, then add the coagulant, and stir at a high speed of 140 revolutions per minute for 120 s to prepare Material B;

[0099] c) Add water to Material A and Material B respectively, stir at a high speed of 120 revolutions per minute for 120 s, stir at a low speed of 45 revolutions per minute for 60 s, and finally mix Material A and Material B and stir at a high speed of 150 revolutions per minute for 90 s. After the stirring is completed, a slurry is obtained.

[0100] d) Pour the mixed slurry into the corresponding test mold, let it stand until initial setting, then remove the mold and place it in the curing room for curing until 28 d.

[0101] When mixing cement mortar, the differences between low-speed stirring and high-speed stirring are mainly reflected in the stirring speed and stirring effect. Speed during low-speed stirring: Usually 30 - 60 revolutions per minute. Characteristics: Low-speed stirring can avoid the generation of air bubbles in the cement mortar. The main purpose is to evenly mix the mortar raw materials to ensure good combination of cement, sand and water, and it is suitable for mixing relatively rough materials. Speed during high-speed stirring: Usually 120 - 150 revolutions per minute or higher. Characteristics: High-speed stirring can effectively improve the mixing efficiency, but it is also easy to introduce air bubbles. High-speed stirring is usually used for mortar that requires high uniformity and fineness, which can completely disperse cement particles, making the mortar more delicate and having better fluidity.

[0102] Comparative Example

[0103] The difference between this comparative example and Example 1 is that graphene oxide, polyethylene oxide and fumed silica are not added.

[0104] Test Example

[0105] Perform performance tests on the grouting materials prepared in the examples and comparative examples. The test results are shown in Tables 4 - 8.

[0106] The test methods and procedures are as follows:

[0107] Fluidity: Refer to "Test Methods for the Homogeneity of Concrete Admixtures" (GB / T 8077 - 2012). Pour the prepared neat cement paste into a frustum cone mold, level it with a spatula, lift the frustum cone mold vertically, start timing for 30 s, and let it flow freely on the glass plane. Measure the two maximum diameters of the neat cement paste in the vertical direction and take the average value as the fluidity.

[0108] Compressive strength: The specimens are made with a cylindrical mold with a diameter of 50 mm and a height of 50 mm. Refer to "Standard Test Method for Mechanical Properties of Ordinary Concrete" (GB50081 - 2002), use an ETM205D - TS microcomputer-controlled electronic universal testing machine for testing, with a loading rate of 0.5 MPa / s, and measure the compressive strength of the material at different ages.

[0109] Mercury intrusion test: For the specimens after 28 days of hydration, take the fragments from the middle part, soak them in absolute ethanol for 7 days to terminate hydration, assuming the contact angle is 140°. Measure the pore size - pore volume distribution curve and the pore size - cumulative pore volume distribution curve. The instrument model used is: Micromeritics AutoPore9520, the measurement range is: atmospheric pressure to 60000 psia, the instrument resolution is: 0.03 psia, the sensor accuracy is: ±0.1% of the full scale, the pore size range is: 6 to 0.003 μm, and the servo control accuracy is: 0.5% of the target value, 5 psia.

[0110] Carbonation resistance test: According to "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082 - 2009): The CO 2 concentration is maintained at (20 ± 3)%, the temperature is controlled at (20 ± 5) °C, the relative humidity in the box is maintained at (70 ± 5)%. Prepare 3 cube specimens with dimensions of 40 mm × 40 mm × 40 mm for each group. After demolding, cure for 7 days, dry in an oven at 40 °C for 48 h, keep the non-molded surface as the carbonated surface, and measure the carbonation depth when removing the specimens at carbonation times of 6 h, 1 d, and 3 d for the remaining surfaces.

[0111] Freeze-thaw test: Refer to the slow freezing method in "Standard Test Method for Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082 - 2009) and "Test Method for Basic Properties of Building Mortar" (JGJ-T 70 - 2009), and conduct freeze-thaw cycle test research with the compressive strength loss, mass loss, and freeze elastic modulus of the specimens after freeze-thaw cycles as the evaluation indexes.

[0112] Table 4 Comparison of fluidity of each example and comparative example / (mm)

[0113]

[0114]

[0115] Table 5 Comparison of compressive strength of each example and comparative example

[0116] 4h 7d 14d 28d Comparative Example 7.5MPa 12.8MPa 18.1MPa 27.98MPa Example 1 8.7MPa 13.4MPa 19MPa 29.89MPa Example 2 10.2MPa 14.6MPa 20.7MPa 35.83MPa Example 3 10.1MPa 14.5MPa 20.5MPa 32.31MPa Example 4 10MPa 14.3MPa 20.3MPa 30.10MPa Example 5 8.5MPa 12.9MPa 18.5MPa 28.96MPa

[0117] Table 6 Comparison of mercury intrusion test results of each example and comparative example

[0118] Porosity (%) Average pore diameter (nm) Comparative Example 22.17 58.79 Example 1 20.31 38.52 Example 2 15.34 19.58 Example 3 16.76 25.58 Example 4 18.63 28.52 Example 5 21.48 51.24

[0119] Table 7 Comparison of carbonation resistance test results of each example and comparative example

[0120]

[0121]

[0122] Comparison of Freeze-Thaw Test Results between Each Example and Comparative Example in Table 8

[0123]

[0124] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A cement-based high-water grouting material with strong serviceability, characterized in that: Grouting materials include base materials and admixtures; The basic materials are calculated by weight and include the following raw materials: Admixtures are calculated based on the volume fraction of the base material and include the following raw materials: Graphene oxide 0.01%-0.05%; Polyethylene oxide 0.05%-0.09%; Fumed silica 0.05%-0.09%.

2. The cement-based high-water grouting material with strong serviceability according to claim 1, characterized in that: The gelling material includes the following raw materials in parts by weight: 450-550 parts of cement; 350-450 parts of anhydrous gypsum powder; 50-150 parts of quicklime powder.

3. A cement-based high-water grouting material with strong serviceability according to claim 2, characterized in that: The cement is sulphoaluminate cement with an Al2O3 content of 29.54%; the SO3 content in anhydrous gypsum powder is 40.1%; and the CaO content in quicklime powder is 79.81%.

4. The cement-based high-water grouting material with strong serviceability according to claim 1, characterized in that: The retarder is anhydrous citric acid with a purity of 99%.

5. The cement-based high-water grouting material with strong serviceability according to claim 1, characterized in that: The water reducing agent is a naphthalene-based high-efficiency water reducing agent with a water reduction rate of 15%.

6. The cement-based high-water grouting material with strong serviceability according to claim 1, characterized in that: The alkaline activator is anhydrous sodium carbonate with a purity of 99%.

7. The cement-based high-water grouting material with strong serviceability according to claim 1, characterized in that: The coagulant is lithium carbonate with a purity of 99%.

8. The cement-based high-water grouting material with strong serviceability according to claim 1, characterized in that: The water-cement ratio of the grouting material is 1:1, and the compressive strength of the grouting material after curing for 14 days is 18-21 MPa.

9. The method for preparing a cement-based high-water grouting material with strong serviceability according to any one of claims 1 to 8, characterized in that: The following steps are involved: a) adding a retarder, a water reducing agent, an alkali activator, graphene oxide, polyethylene oxide and fumed silica to cement, and stirring at a low speed for 100 to 150 seconds to prepare material A; b) Mix quicklime powder and anhydrous gypsum powder, then add accelerator, stir at low speed for 100-150s to make material B; c) adding water to material A and material B respectively, stirring at a low speed for 100 to 150 seconds, stirring at a high speed for 30 to 90 seconds, and finally mixing material A and material B, stirring at a high speed for 60 to 120 seconds, and obtaining a slurry after the stirring is completed; d) Pour the mixed slurry into the corresponding test mold, let it stand for initial setting, then remove the mold and place it in a curing room for curing for up to 28 days.

10. Use of a cement-based high-water grouting material with strong serviceability as claimed in any one of claims 1 to 8 in surrounding rock support of coal mine tunnels.

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