A high-performance cement-based slightly expanding filling grouting material and its preparation method

Abstract

A high-performance cement-based slightly expanding filling grouting material and its preparation method belong to the technical field of inorganic cementitious materials. The high-performance cement-based slightly expanding filling grouting material is composed of portland cement, fly ash, graded aggregate, aluminum powder coated with aluminum silicate, magnesium oxide coated with calcium silicate, iron powder coated with tung oil, formate calcium early strength agent, polycarboxylate water reducing agent powder, and water. The high-performance cement-based slightly expanding filling grouting material obtained by the present invention has a fluidity of 432 - 441 mm, a 28-day compressive strength of 63.5 - 65.2 MPa, a 28-day flexural strength of 14.3 - 15.1 MPa, a 28-day shrinkage rate of 0.01 - 0.04%, and a 10-time freeze-thaw expansion rate of 0.03 - 0.06%.

Description

Technical Field

[0001] The present invention relates to a high-performance cement-based slightly expanding filling grouting material and a preparation method thereof, belonging to the technical field of inorganic cementitious materials. Background Art

[0002] The grouting technology plays an irreplaceable and important role in engineering fields such as civil engineering, water conservancy, transportation, and mining. It mainly includes the reinforcement of building foundations and settlement prevention, the anti-seepage treatment and reinforcement of poor geological bodies in dam foundations, the grouting reinforcement of water-rich areas in subways and tunnels, the treatment and grouting reinforcement of diseases such as the void collapse of subgrades of highways and railways and airport runways, the grouting reinforcement of the anchorage area during slope support and foundation pit excavation, the post-grouting used to ensure the bearing capacity of cast-in-place piles, and the repair and reinforcement of cracks in cultural relics. The most core and key part of the grouting technology is the grouting material. At present, the selectable grouting materials are mainly divided into two categories: organic and inorganic. The cost of organic grouting materials is generally relatively high and it is relatively easy to release or leave substances that have a negative impact on the environment. The cost of inorganic grouting materials is generally relatively low. Especially for traditional silicate cement-based inorganic grouting materials, as the most widely used inorganic grouting material, it is very cheap and has the advantages of good durability and high strength of the stone body, but there are problems such as poor injectability, low strength, and large shrinkage rate during the consolidation process. At the same time, due to the large shrinkage of the stone body after hardening, the friction between the grouting body and the crack matrix decreases, and the compressive strength and flexural strength decrease. Therefore, there is an urgent need for a high-performance cement-based filling grouting material with good fluidity, small shrinkage after hardening, high compressive strength, and high flexural strength in cement-based inorganic filling grouting materials.

[0003] Chinese Patent CN114605102A discloses a rapid-setting slightly expanding cement-based grouting material with anti-dispersion performance and a preparation method thereof. The anti-dispersion performance improver is composed of the following components in parts by weight: 10-20 parts of acrylamide, 1-3 parts of N,N,N',N'-tetramethylethylenediamine, 0-3 parts of ammonium persulfate, 0-10 parts of xanthan gum, 0-10 parts of carboxymethyl cellulose, and 80 parts of water. The grouting material is composed of the following components: 200 parts of slightly expanding cement matrix, 0-25 parts of rapid-setting agent, 0-50 parts of anti-dispersion performance improver, and 120-200 parts of water. The rapid-setting slightly expanding cement-based grouting material prepared by this patent contains a large amount of organic substances, and the cost will definitely be relatively high. In addition, the highest compressive strength of the grouting material obtained by this patent after curing can only reach 12.6 MPa, which is very low and difficult to meet the requirements of general projects.

[0004] Chinese Patent CN115215607A discloses a cement-based gelling expansive grouting material for coastal karst and its preparation method. The expansive grouting material consists of two components, A and B. Component A is a gelling material with pozzolanic properties, water, and an expansive agent in an amount of 0.01% - 6.0%, and the water-cement ratio is (0.5 - 0.9):1. Component B includes, by weight percentage: 0.2 - 1.3% of water-soluble plant gum, 0.5 - 2.0% of polyacrylamide, 0.01 - 2.0% of polyacrylate-derived salt, 0.02 - 1.5% of complexing agent, 0.05 - 1.5% of alcohol polysaccharide, 2 - 70% of water glass, and 42.3 - 90.3% of water. The cement-based gelling expansive grouting material prepared by this patent adds a large amount of organic components, and the volume expansion ratio of the obtained grouting material is very high, resulting in a very low consolidation body, which is only suitable for temporary engineering reinforcement and difficult to be used for long-term reinforcement.

[0005] From the above discussion, it can be seen that the current cement-based slightly expansive filling grouting material still has significant drawbacks such as poor injectability, large shrinkage of the stone body after hardening, and reduction of flexural strength and compressive strength. Therefore, developing a high-performance cement-based slightly expansive filling grouting material with good fluidity, small shrinkage after hardening, large compressive strength and flexural strength has very practical significance for improving the quality of grouting technology. Summary of the Invention

[0006] Aiming at the deficiencies of the above-mentioned existing technologies, the present invention provides a high-performance cement-based slightly expansive filling grouting material and its preparation method, achieving the following invention objectives: preparing a high-performance cement-based slightly expansive filling grouting material with good fluidity, small shrinkage after hardening, large compressive strength and flexural strength.

[0007] To achieve the above invention objectives, the present invention adopts the following technical solutions:

[0008] A high-performance cement-based slightly expansive filling grouting material and its preparation method. The raw material composition of the high-performance cement-based slightly expansive filling grouting material includes portland cement, fly ash, graded aggregate, aluminum powder coated with aluminum silicate, magnesium oxide coated with calcium silicate, iron powder coated with tung oil, formate early strength agent, polycarboxylate superplasticizer powder, and water.

[0009] The raw material composition of the high-performance cement-based slightly expansive filling grouting material is, by weight:

[0010] 350 - 500 parts of portland cement,

[0011] 200 - 350 parts of fly ash,

[0012] 220 - 360 parts of graded aggregate,

[0013] 10 - 40 parts of aluminum powder coated with aluminum silicate,

[0014] 15 to 50 parts of magnesium oxide coated with calcium silicate,

[0015] 25 to 60 parts of iron powder coated with tung oil,

[0016] 10 to 35 parts of calcium formate early strength agent,

[0017] 9 to 20 parts of polycarboxylate superplasticizer powder,

[0018] 250 to 400 parts of water;

[0019] The fly ash is Class II fly ash specified in the national standard "GB / T 1596 - 2005 Fly Ash Used in Cement and Concrete", with a particle size of 1 to 90 μm;

[0020] The graded aggregate is river sand meeting the grading standard. The grading standard is: the percentage passing through the 4.75 mm sieve hole is 100 wt%, the percentage passing through the 2.36 mm sieve hole is 90 - 96 wt%, the percentage passing through the 1.18 mm sieve hole is 70 - 90 wt%, and the percentage passing through the 0.6 mm sieve hole is 60 - 85 wt%;

[0021] The following is a further improvement of the above technical solution:

[0022] Step 1: Preparation of aluminum powder coated with aluminum silicate

[0023] After the aluminum powder is dried at 40 - 60 °C for 9 - 15 hours, it is put into a dry and anhydrous high - speed dispersion kettle. Then acetone is added. While controlling the stirring rate at 5000 - 9000 revolutions per minute, it is strongly dispersed for 4 - 8 hours. Then the dispersion rate is reduced to 1500 - 2500 revolutions per minute. Next, hexamethyldisilazane is added into the high - speed dispersion kettle, and the dispersion reaction continues for 1 - 2.5 hours. Then deionized water is added into the high - speed dispersion kettle, and the dispersion reaction continues for 2 - 5 hours. After centrifugal separation, the separated solid is washed 2 - 4 times with anhydrous ethanol and then dried at 50 - 60 °C for 4 - 7 hours to obtain aluminum powder coated with silicone. Then the aluminum powder coated with silicone and the aluminum sulfate aqueous solution are added into the high - speed dispersion kettle. While controlling the stirring rate at 6000 - 8500 revolutions per minute, it is strongly dispersed for 2 - 3.5 hours. Then the dispersion rate is reduced to 1000 - 2000 revolutions per minute. Next, the sodium metasilicate aqueous solution is dropped into the high - speed dispersion kettle at a rate of 0.05 - 0.6 grams per second. After the dropping is completed, the dispersion reaction continues for 2.5 - 4 hours. After filtration and separation, the filtered solid is washed 2 - 3 times with deionized water and then dried at 50 - 70 °C for 6 - 13 hours to obtain aluminum powder coated with aluminum silicate;

[0024] The particle size of the aluminum powder is 0.1 - 3 μm;

[0025] The mass ratio of the aluminum powder, acetone, hexamethyldisilazane, and deionized water is 20~50:90~180:9~20:0.3~0.9;

[0026] In the aluminum sulfate aqueous solution, the mass fraction of aluminum sulfate is 18~28wt%;

[0027] In the sodium metasilicate aqueous solution, the mass fraction of sodium metasilicate is 20~33wt%, and the modulus of sodium metasilicate is 1.5~2.5;

[0028] The mass ratio of the organosilicon-coated aluminum powder, aluminum sulfate aqueous solution, and sodium metasilicate aqueous solution is 10~45:80~200:50~130.

[0029] Step 2: Preparation of calcium silicate-coated magnesium oxide

[0030] Add magnesium oxide powder and calcium chloride aqueous solution into a high-speed dispersion kettle. Under the condition of controlling the stirring rate at 7000~9500 revolutions per minute, strongly disperse for 1~2.5 hours, then reduce the dispersion rate to 1000~2000 revolutions per minute. Next, dropwise add the sodium metasilicate aqueous solution into the high-speed dispersion kettle at a rate of 0.1~0.8 grams per second. After the dropping is completed, continue the dispersion reaction for 1.5~2.5 hours, then filter and separate. The filtered solid is washed 2~3 times with deionized water, and then dried at 70~90°C for 5~11 hours to obtain calcium silicate-coated magnesium oxide;

[0031] The particle size of the magnesium oxide powder is 0.3~2μm;

[0032] In the calcium chloride aqueous solution, the mass fraction of calcium chloride is 20~40wt%;

[0033] In the sodium metasilicate aqueous solution, the mass fraction of sodium metasilicate is 20~33wt%, and the modulus of sodium metasilicate is 1.5~2.5;

[0034] The mass ratio of the magnesium oxide powder, calcium chloride aqueous solution, and sodium metasilicate aqueous solution is 20~50:100~250:60~180.

[0035] Step 3: Preparation of tung oil-coated iron powder

[0036] Add iron powder, diisostearoyl aluminum acid isopropyl ester, aluminum isopropoxide, and toluene into a high-speed dispersion kettle. Under the condition of controlling the dispersion rate at 6000~8500 revolutions per minute, strongly disperse for 3~6 hours, then add tung oil and continue to disperse for 4~7 hours. Then, send the dispersion liquid into a spray dryer for spray drying granulation. Under the conditions of controlling the spray pressure at 0.3~0.8MPa, the drying temperature at 90~115°C, and the drying time at 1~2.5 seconds, obtain tung oil-coated iron powder with a particle size of 1~5μm;

[0037] The particle size of the iron powder is 0.3 - 4 μm;

[0038] The mass ratio of the iron powder, aluminum diisostearoyl oxyisopropyl aluminate, aluminum isopropoxide, toluene, and tung oil is 20 - 60:0.5 - 2:1 - 4:70 - 180:9 - 35.

[0039] Step 4: Preparation of the cement - based slightly expanding filling grouting material

[0040] According to the specific formula of the high - performance cement - based slightly expanding filling grouting material by weight, add fly ash, aluminum powder coated with aluminum silicate, magnesium oxide coated with calcium silicate, iron powder coated with tung oil, formate early - strength agent, polycarboxylate water - reducing agent powder, and half of the weight of water in the formula into a mixer. Control the stirring rate at 80 - 130 revolutions per minute, stir and mix for 20 - 35 minutes, then add Portland cement, graded aggregate, and the other half of the weight of water in the formula, and continue to stir and mix for 10 - 20 minutes, and then discharge to obtain the high - performance cement - based slightly expanding filling grouting material.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] 1. In the high - performance cement - based slightly expanding filling grouting material prepared by the present invention, aluminum powder with a relatively high expansion rate is added. Aluminum powder is a concrete expansion agent with very active reaction properties. In order to control the expansion rate of aluminum powder and the start time of the expansion effect, the present invention coats the aluminum powder with aluminum silicate. Specifically, aluminum silicate is generated on the surface of the aluminum powder through the coprecipitation reaction of aluminum sulfate and sodium metasilicate and adheres to the surface of the aluminum powder. The above coprecipitation reaction occurs in an aqueous medium. In order to avoid the reaction of aluminum powder with water, the present invention first covers a layer of organosilicon on the surface of the aluminum powder through the hydrolysis reaction of hexamethyldisilazane, thus avoiding the reaction of aluminum powder with water. After the aluminum powder is coated with aluminum silicate, in the strongly alkaline environment during the curing process of the high - performance cement - based slightly expanding filling grouting material, the aluminum silicate on the surface gradually dissolves, and the aluminum powder slowly reacts with the water in the system, slowly releasing gas, playing a controllable micro - expansion role and reducing the shrinkage rate of the cured body of the cement - based slightly expanding filling grouting material;

[0043] 2. The present invention coats the magnesium oxide powder with calcium silicate generated by the coprecipitation reaction of calcium chloride and sodium metasilicate. After coating, the reaction activity of the magnesium oxide powder during the curing process of the cement - based slightly expanding filling grouting material is reduced. In this way, the reaction expansion effect of the magnesium oxide powder will be delayed to a considerable extent, enabling the magnesium oxide powder to have the effect of delayed expansion. In the early - strength stage of Portland cement, magnesium oxide does not play a major expansion role, while in the later stage of the curing of the main components of Portland cement, magnesium oxide begins to release a large amount of expansion reaction activity, which can effectively offset the large shrinkage in the later stage of the curing of Portland cement, more effectively play a micro - expansion effect, maintain the best state of the density of the cured body of Portland cement, and thus obtain a consolidation body with better mechanical properties;

[0044] 3. The present invention coats the surface of iron powder with tung oil. Under the action of two driers, namely aluminum di(stearoyl isopropyl) aluminate and aluminum isopropoxide, and in combination with the spray drying process, as the toluene solvent volatilizes, the tung oil solidifies into a relatively dense film on the surface of the iron powder. After the iron powder is coated with the tung oil film and added to the high-performance cement-based slightly expanding filling grouting material formula, during the curing process of the grouting material, as the alkalinity of the reaction system increases, the tung oil film slowly degrades, and the internal iron powder is gradually released into the reaction system to generate iron hydroxide gel. This gel has a certain degree of swelling effect, can effectively fill the gaps in the curing network of portland cement, play a role in filling the pores of the consolidated body and increasing the density of the consolidated body, and ultimately improve the mechanical properties of the consolidated body of the high-performance cement-based slightly expanding filling grouting material;

[0045] 4. The high-performance cement-based slightly expanding filling grouting material obtained by the present invention has a fluidity of 432 - 441 mm, a 28-day compressive strength of 63.5 - 65.2 MPa, a 28-day flexural strength of 14.3 - 15.1 MPa, a 28-day shrinkage rate of 0.01 - 0.04%, and a 10-time freeze-thaw expansion rate of 0.03 - 0.06%. Specific Embodiments

[0046] The following describes the preferred embodiments of the present invention. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0047] Example 1: A preparation method of a high-performance cement-based slightly expanding filling grouting material

[0048] Step 1: Preparation of aluminum powder coated with aluminum silicate

[0049] After the aluminum powder is dried at 55°C for 13 hours, it is put into a dry and anhydrous high-speed dispersion kettle. Then, acetone is added. Under the condition of controlling the stirring rate at 8000 revolutions per minute, it is strongly dispersed for 7 hours. Then, the dispersion rate is reduced to 2200 revolutions per minute. Next, hexamethyldisilazane is added into the high-speed dispersion kettle, and the dispersion reaction continues for 2 hours. Then, deionized water is added into the high-speed dispersion kettle, and the dispersion reaction continues for 3 hours. After centrifugal separation, the separated solid is washed 3 times with anhydrous ethanol and then dried at 56°C for 6 hours to obtain organosilicon-coated aluminum powder. Then, the organosilicon-coated aluminum powder and an aqueous solution of aluminum sulfate are added into the high-speed dispersion kettle. Under the condition of controlling the stirring rate at 7500 revolutions per minute, it is strongly dispersed for 3 hours. Then, the dispersion rate is reduced to 1600 revolutions per minute. Next, an aqueous solution of sodium metasilicate is dropped into the high-speed dispersion kettle at a rate of 0.4 grams per second. After the dropping is completed, the dispersion reaction continues for 3 hours. After filtration and separation, the filtered solid is washed 2 times with deionized water and then dried at 66°C for 11 hours to obtain aluminum powder coated with aluminum silicate;

[0050] The particle size of the aluminum powder is 1 μm;

[0051] The mass ratio of the aluminum powder, acetone, hexamethyldisilazane, and deionized water is 40:130:13:0.7;

[0052] In the aluminum sulfate aqueous solution, the mass fraction of aluminum sulfate is 23 wt%;

[0053] In the sodium metasilicate aqueous solution, the mass fraction of sodium metasilicate is 26 wt%, and the modulus of sodium metasilicate is 2;

[0054] The mass ratio of the organosilicon-coated aluminum powder, aluminum sulfate aqueous solution, and sodium metasilicate aqueous solution is 30:120:110.

[0055] Step 2: Preparation of calcium silicate-coated magnesium oxide

[0056] Add magnesium oxide powder and calcium chloride aqueous solution to a high-speed dispersion kettle. Under the condition of controlling the stirring rate at 8000 revolutions per minute, after strong dispersion for 2 hours, reduce the dispersion rate to 1600 revolutions per minute. Then, dropwise add sodium metasilicate aqueous solution into the high-speed dispersion kettle at a rate of 0.4 grams per second. After the dropping is completed, continue the dispersion reaction for 2 hours, then filter and separate. The filtered solid is washed twice with deionized water and then dried at 85 °C for 8 hours to obtain calcium silicate-coated magnesium oxide;

[0057] The particle size of the magnesium oxide powder is 1 μm;

[0058] In the calcium chloride aqueous solution, the mass fraction of calcium chloride is 28 wt%;

[0059] In the sodium metasilicate aqueous solution, the mass fraction of sodium metasilicate is 27 wt%, and the modulus of sodium metasilicate is 2;

[0060] The mass ratio of the magnesium oxide powder, calcium chloride aqueous solution, and sodium metasilicate aqueous solution is 40:190:120.

[0061] Step 3: Preparation of tung oil-coated iron powder

[0062] Add iron powder, diisopropylaluminum stearate, aluminum isopropoxide, and toluene to a high-speed dispersion kettle. Under the condition of controlling the dispersion rate at 7500 revolutions per minute, after strong dispersion for 4 hours, add tung oil and continue dispersion for 6 hours. Then, send the dispersion liquid into a spray dryer for spray drying granulation. Under the conditions of controlling the spray pressure at 0.6 MPa, the drying temperature at 110 °C, and the drying time at 2 seconds, obtain tung oil-coated iron powder with a particle size of 4 μm;

[0063] The particle size of the iron powder is 3 μm;

[0064] The mass ratio of the iron powder, aluminum isopropyl dioctoate, aluminum isopropoxide, toluene, and tung oil is 35:1:2:150:25.

[0065] Step 4: Preparation of the cement-based slightly expanding filling grouting material

[0066] The raw material composition of the high-performance cement-based slightly expanding filling grouting material is as follows, by weight:

[0067] Portland cement: 400 parts,

[0068] Fly ash: 300 parts,

[0069] Graded aggregate: 320 parts,

[0070] Aluminum powder coated with aluminum silicate: 30 parts,

[0071] Magnesium oxide coated with calcium silicate: 40 parts,

[0072] Iron powder coated with tung oil: 45 parts,

[0073] Calcium formate early strength agent: 25 parts,

[0074] Powder of polycarboxylate water reducer: 17 parts,

[0075] Water: 350 parts;

[0076] The fly ash is Class II fly ash specified in the national standard "GB / T 1596-2005 Fly Ash Used in Cement and Concrete", with a particle size of 40 μm;

[0077] The graded aggregate is river sand meeting the grading standard. The grading standard is as follows: the percentage passing through the 4.75 mm sieve hole is 100 wt%, the percentage passing through the 2.36 mm sieve hole is 94 wt%, the percentage passing through the 1.18 mm sieve hole is 85 wt%, and the percentage passing through the 0.6 mm sieve hole is 80 wt%;

[0078] According to the raw material composition of the high-performance cement-based slightly expanding filling grouting material by weight, add fly ash, aluminum powder coated with aluminum silicate, magnesium oxide coated with calcium silicate, iron powder coated with tung oil, calcium formate early strength agent, powder of polycarboxylate water reducer, and half of the weight of water in the formula to the mixer. Control the stirring rate at 110 revolutions per minute and stir and mix for 30 minutes. Then add Portland cement, graded aggregate, and the other half of the weight of water in the formula, and continue to stir and mix for 16 minutes, and then discharge to obtain the high-performance cement-based slightly expanding filling grouting material.

[0079] Example 2: A preparation method of a high-performance cement-based slightly expanding filling grouting material

[0080] Step 1: Preparation of aluminum powder coated with aluminum silicate

[0081] After the aluminum powder is dried at 40 °C for 9 hours, it is put into a dry and anhydrous high-speed dispersion kettle. Then, acetone is added. While controlling the stirring rate at 5000 revolutions per minute, it is strongly dispersed for 4 hours. After that, the dispersion rate is reduced to 1500 revolutions per minute. Then, hexamethyldisilazane is added into the high-speed dispersion kettle. After continuing the dispersion reaction for 1 hour, deionized water is added into the high-speed dispersion kettle. Then, after continuing the dispersion reaction for 2 hours, centrifugal separation is carried out. The separated solid is washed twice with anhydrous ethanol and then dried at 50 °C for 4 hours to obtain organosilicon-coated aluminum powder. Then, the organosilicon-coated aluminum powder and the aluminum sulfate aqueous solution are added into the high-speed dispersion kettle. While controlling the stirring rate at 6000 revolutions per minute, it is strongly dispersed for 2 hours. After that, the dispersion rate is reduced to 1000 revolutions per minute. Then, an aqueous solution of sodium metasilicate is dropped into the high-speed dispersion kettle at a rate of 0.05 grams per second. After the dropping is completed, the dispersion reaction is continued for 2.5 hours. Then, filtration separation is carried out. The filtered solid is washed twice with deionized water and then dried at 50 °C for 6 hours to obtain aluminum silicate-coated aluminum powder;

[0082] The particle size of the aluminum powder is 0.1 μm;

[0083] The mass ratio of the aluminum powder, acetone, hexamethyldisilazane, and deionized water is 20:90:9:0.3;

[0084] In the aluminum sulfate aqueous solution, the mass fraction of aluminum sulfate is 18 wt%;

[0085] In the aqueous solution of sodium metasilicate, the mass fraction of sodium metasilicate is 20 wt%, and the modulus of sodium metasilicate is 1.5;

[0086] The mass ratio of the organosilicon-coated aluminum powder, the aluminum sulfate aqueous solution, and the aqueous solution of sodium metasilicate is 10:80:50.

[0087] Step 2: Preparation of calcium silicate-coated magnesium oxide

[0088] Magnesium oxide powder and an aqueous solution of calcium chloride are added into a high-speed dispersion kettle. While controlling the stirring rate at 7000 revolutions per minute, it is strongly dispersed for 1 hour. After that, the dispersion rate is reduced to 1000 revolutions per minute. Then, an aqueous solution of sodium metasilicate is dropped into the high-speed dispersion kettle at a rate of 0.1 grams per second. After the dropping is completed, the dispersion reaction is continued for 1.5 hours. Then, filtration separation is carried out. The filtered solid is washed twice with deionized water and then dried at 70 °C for 5 hours to obtain calcium silicate-coated magnesium oxide;

[0089] The particle size of the magnesium oxide powder is 0.3 μm;

[0090] In the aqueous solution of calcium chloride, the mass fraction of calcium chloride is 20 wt%;

[0091] In the aqueous solution of sodium metasilicate, the mass fraction of sodium metasilicate is 20 wt%, and the modulus of sodium metasilicate is 1.5;

[0092] The mass ratio of the magnesium oxide powder, the calcium chloride aqueous solution, and the sodium metasilicate aqueous solution is 20:100:60.

[0093] Step 3: Preparation of tung oil-coated iron powder

[0094] Add iron powder, diisopropylaluminum distearate, aluminum isopropoxide, and toluene into a high-speed dispersion kettle. Under the condition of controlling the dispersion rate at 6000 revolutions per minute, disperse strongly for 3 hours, then add tung oil, and continue to disperse for 4 hours. Then, send the dispersion liquid into a spray dryer for spray drying granulation. Under the conditions of controlling the spray pressure at 0.3 MPa, the drying temperature at 90 °C, and the drying time at 1 second, tung oil-coated iron powder with a particle size of 1 μm is obtained;

[0095] The particle size of the iron powder is 0.3 μm;

[0096] The mass ratio of the iron powder, diisopropylaluminum distearate, aluminum isopropoxide, toluene, and tung oil is 20:0.5:1:70:9.

[0097] Step 4: Preparation of cement-based slightly expanding filling grouting material

[0098] The raw material composition of the high-performance cement-based slightly expanding filling grouting material is as follows, by weight:

[0099] 350 parts of portland cement,

[0100] 200 parts of fly ash,

[0101] 220 parts of graded aggregate,

[0102] 10 parts of aluminum powder coated with aluminum silicate,

[0103] 15 parts of magnesium oxide coated with calcium silicate,

[0104] 25 parts of tung oil-coated iron powder,

[0105] 10 parts of calcium formate early strength agent,

[0106] 9 parts of polycarboxylate water reducer powder,

[0107] 250 parts of water;

[0108] The fly ash is Class II fly ash specified in the national standard "GB / T 1596 - 2005 Fly Ash Used in Cement and Concrete", and the particle size is 1 μm;

[0109] The graded aggregate is river sand meeting the grading standard. The grading standard is as follows: the percentage passing through the 4.75 mm sieve opening is 100 wt%, the percentage passing through the 2.36 mm sieve opening is 90 wt%, the percentage passing through the 1.18 mm sieve opening is 70 wt%, and the percentage passing through the 0.6 mm sieve opening is 60 wt%.

[0110] According to the raw material composition of the high-performance cement-based slightly expanding filling grouting material by weight, fly ash, aluminum powder coated with aluminum silicate, magnesium oxide coated with calcium silicate, iron powder coated with tung oil, formate calcium early strength agent, polycarboxylate water-reducing agent powder, and half of the water in the formula are added to a mixer. Under the condition of controlling the stirring rate at 80 revolutions per minute, after stirring and mixing for 20 minutes, then Portland cement, graded aggregate, and the other half of the water in the formula are added, and after continuing to stir and mix for 10 minutes, the high-performance cement-based slightly expanding filling grouting material is obtained by discharging.

[0111] Example 3: A preparation method of a high-performance cement-based slightly expanding filling grouting material

[0112] Step 1: Preparation of aluminum powder coated with aluminum silicate

[0113] After drying the aluminum powder at 60 °C for 15 hours, it is put into a dry and anhydrous high-speed dispersion kettle. Then acetone is added. Under the condition of controlling the stirring rate at 9000 revolutions per minute, after strongly dispersing for 8 hours, the dispersion rate is reduced to 2500 revolutions per minute. Then hexamethyldisilazane is added into the high-speed dispersion kettle, and after continuing to disperse and react for 2.5 hours, deionized water is added into the high-speed dispersion kettle, and then after continuing to disperse and react for 5 hours, centrifugal separation is carried out. The separated solid is washed 4 times with anhydrous ethanol and then dried at 60 °C for 7 hours to obtain aluminum powder coated with silicone. Then the aluminum powder coated with silicone and the aluminum sulfate aqueous solution are added into the high-speed dispersion kettle. Under the condition of controlling the stirring rate at 8500 revolutions per minute, after strongly dispersing for 3.5 hours, the dispersion rate is reduced to 2000 revolutions per minute. Then an aqueous sodium metasilicate solution is dropped into the high-speed dispersion kettle at a rate of 0.6 grams per second. After the dropping is completed, after continuing to disperse and react for 4 hours, filtration separation is carried out. The filtered solid is washed 3 times with deionized water and then dried at 70 °C for 13 hours to obtain aluminum powder coated with aluminum silicate;

[0114] The particle size of the aluminum powder is 3 μm;

[0115] The mass ratio of the aluminum powder, acetone, hexamethyldisilazane, and deionized water is 50:180:20:0.9;

[0116] In the aluminum sulfate aqueous solution, the mass fraction of aluminum sulfate is 28 wt%;

[0117] In the aqueous sodium metasilicate solution, the mass fraction of sodium metasilicate is 33 wt%, and the modulus of sodium metasilicate is 2.5;

[0118] The mass ratio of the silicone-coated aluminum powder, aluminum sulfate aqueous solution, and sodium metasilicate aqueous solution is 45:200:130.

[0119] Step 2: Preparation of calcium silicate-coated magnesium oxide

[0120] Add magnesium oxide powder and calcium chloride aqueous solution to a high-speed dispersion kettle. Control the stirring rate at 9,500 revolutions per minute and disperse strongly for 2.5 hours. Then reduce the dispersion rate to 2,000 revolutions per minute. Next, dropwise add sodium metasilicate aqueous solution into the high-speed dispersion kettle at a rate of 0.8 grams per second. After the dropping is completed, continue the dispersion reaction for 2.5 hours, then filter and separate. Wash the filtered solid with deionized water 3 times, and then dry it at 90 °C for 11 hours to obtain calcium silicate-coated magnesium oxide;

[0121] The particle size of the magnesium oxide powder is 2 μm;

[0122] In the calcium chloride aqueous solution, the mass fraction of calcium chloride is 40 wt%;

[0123] In the sodium metasilicate aqueous solution, the mass fraction of sodium metasilicate is 33 wt%, and the modulus of sodium metasilicate is 2.5;

[0124] The mass ratio of the magnesium oxide powder, calcium chloride aqueous solution, and sodium metasilicate aqueous solution is 50:250:180.

[0125] Step 3: Preparation of tung oil-coated iron powder

[0126] Add iron powder, diisopropyl stearoyl aluminate, aluminum isopropoxide, and toluene to a high-speed dispersion kettle. Control the dispersion rate at 8,500 revolutions per minute and disperse strongly for 6 hours. Then add tung oil and continue to disperse for 7 hours. Then send the dispersion liquid into a spray dryer for spray drying granulation. Under the conditions of controlling the spray pressure at 0.8 MPa, the drying temperature at 115 °C, and the drying time at 2.5 seconds, obtain tung oil-coated iron powder with a particle size of 5 μm;

[0127] The particle size of the iron powder is 4 μm;

[0128] The mass ratio of the iron powder, diisopropyl stearoyl aluminate, aluminum isopropoxide, toluene, and tung oil is 60:2:4:180:35.

[0129] Step 4: Preparation of cement-based slightly expanding filling grouting material

[0130] The raw material composition of the high-performance cement-based slightly expanding filling grouting material is, by weight:

[0131] Portland cement 500 parts,

[0132] Fly ash 350 parts,

[0133] 360 parts of graded aggregate,

[0134] 40 parts of aluminum powder coated with aluminum silicate,

[0135] 50 parts of magnesium oxide coated with calcium silicate,

[0136] 60 parts of iron powder coated with tung oil,

[0137] 35 parts of calcium formate early strength agent,

[0138] 20 parts of polycarboxylate superplasticizer powder,

[0139] 400 parts of water;

[0140] The fly ash is Class II fly ash specified in the national standard "GB / T 1596 - 2005 Fly Ash Used in Cement and Concrete", with a particle size of 90 μm;

[0141] The graded aggregate is river sand meeting the grading standard. The grading standard is: the percentage passing through the 4.75 mm sieve hole is 100 wt%, the percentage passing through the 2.36 mm sieve hole is 96 wt%, the percentage passing through the 1.18 mm sieve hole is 90 wt%, and the percentage passing through the 0.6 mm sieve hole is 85 wt%;

[0142] According to the raw material composition of the high - performance cement - based slightly expanding filling grouting material in parts by weight, add fly ash, aluminum powder coated with aluminum silicate, magnesium oxide coated with calcium silicate, iron powder coated with tung oil, calcium formate early strength agent, polycarboxylate superplasticizer powder and half of the water in the formula to the mixer. Control the stirring rate at 130 revolutions per minute, stir and mix for 35 minutes, then add Portland cement, graded aggregate and the other half of the water in the formula, and continue to stir and mix for 20 minutes, and then discharge to obtain the high - performance cement - based slightly expanding filling grouting material.

[0143] Comparative Example 1: On the basis of Example 1, without performing Step 1, the preparation of aluminum powder coated with aluminum silicate, and in Step 4, the preparation of the cement - based slightly expanding filling grouting material, replace 30 parts of aluminum powder coated with aluminum silicate with 30 parts of aluminum powder in equal amount. The specific operation is as follows:

[0144] Do not perform Step 1, the preparation of aluminum powder coated with aluminum silicate;

[0145] The operations in Steps 2 and 3 are the same as those in Example 1;

[0146] Step 4, the preparation of the cement - based slightly expanding filling grouting material

[0147] Replace 30 parts of aluminum powder coated with aluminum silicate with 30 parts of aluminum powder in equal amount, and other operations are the same as those in Example 1;

[0148] The particle size of the aluminum powder is 1 μm.

[0149] Comparative Example 2: Based on Example 1, without performing Step 2, the preparation of calcium silicate-coated magnesium oxide, and in Step 4, the preparation of the cement-based slightly expanding filling grouting material, 40 parts of calcium silicate-coated magnesium oxide are replaced with 40 parts of magnesium oxide powder in equal amounts. The specific operations are as follows:

[0150] Step 1: The operation is the same as in Example 1;

[0151] Do not perform Step 2, the preparation of calcium silicate-coated magnesium oxide;

[0152] Step 3: The operation is the same as in Example 1;

[0153] Step 4: The preparation of the cement-based slightly expanding filling grouting material

[0154] Replace 40 parts of calcium silicate-coated magnesium oxide with 40 parts of magnesium oxide powder in equal amounts, and other operations are the same as in Example 1;

[0155] The particle size of the magnesium oxide powder is 1 μm.

[0156] Comparative Example 3: Based on Example 1, without performing Step 3, the preparation of tung oil-coated iron powder, and in Step 4, the preparation of the cement-based slightly expanding filling grouting material, 45 parts of tung oil-coated iron powder are replaced with 45 parts of iron powder in equal amounts. The specific operations are as follows:

[0157] Steps 1 and 2: The operations are the same as in Example 1;

[0158] Do not perform Step 3, the preparation of tung oil-coated iron powder;

[0159] Step 4: The preparation of the cement-based slightly expanding filling grouting material

[0160] Replace 45 parts of tung oil-coated iron powder with 45 parts of iron powder in equal amounts, and other operations are the same as in Example 1;

[0161] The particle size of the iron powder is 3 μm.

[0162] Comparative Example 4: Based on Example 1, without performing Step 1, the preparation of aluminum silicate-coated aluminum powder, nor Step 2, the preparation of calcium silicate-coated magnesium oxide, and Step 3, the preparation of tung oil-coated iron powder. In Step 4, the preparation of the cement-based slightly expanding filling grouting material, 30 parts of aluminum silicate-coated aluminum powder are replaced with 30 parts of aluminum powder, 40 parts of calcium silicate-coated magnesium oxide are replaced with 40 parts of magnesium oxide powder, and 45 parts of tung oil-coated iron powder are replaced with 45 parts of iron powder. The specific operations are as follows:

[0163] Do not perform Step 1, the preparation of aluminum silicate-coated aluminum powder;

[0164] Do not perform Step 2, the preparation of calcium silicate-coated magnesium oxide;

[0165] Do not perform Step 3, the preparation of tung oil-coated iron powder;

[0166] Step 4, Preparation of Cement-based Micro-expansion Filling Grouting Material

[0167] Replace 30 parts of aluminum powder coated with aluminum silicate with 30 parts of aluminum powder, 40 parts of magnesium oxide coated with calcium silicate with 40 parts of magnesium oxide powder, and 45 parts of iron powder coated with tung oil with 45 parts of iron powder. Other operations are the same as in Example 1;

[0168] The particle size of the aluminum powder is 1 μm;

[0169] The particle size of the magnesium oxide powder is 1 μm;

[0170] The particle size of the iron powder is 3 μm.

[0171] Performance Test:

[0172] For the high-performance cement-based micro-expansion filling grouting materials obtained in Examples 1, 2, 3 and Comparative Examples 1, 2, 3, 4, test performance indexes such as fluidity, 28-day compressive strength, 28-day flexural strength, 28-day shrinkage rate, and freeze-thaw expansion rate with reference to the "Technical Specification for Application of Cement-based Grouting Materials" (GB / T50448-2015). The specific test data are shown in Table 1;

[0173] Table 1

[0174]

[0175] From the data in Table 1, it can be seen that the fluidity of Examples 1-3 is above 430 mm, the 28-day compressive strength is above 63.5 MPa, the 28-day flexural strength is above 14.3 MPa, the 28-day shrinkage rate is less than 0.04%, and the 10-time freeze-thaw expansion rate is below 0.06%. This indicates that the high-performance cement-based slightly expanding filling grouting material prepared by the present invention has the advantages of good fluidity, small shrinkage after hardening, high compressive strength and flexural strength, etc.; in Comparative Example 1, the aluminum powder is not coated with aluminum silicate, and the fluidity of Comparative Example 1 decreases, and the reduction amplitude of the 28-day compressive strength and the 28-day flexural strength is very large. The 28-day shrinkage rate increases to 3.8%, and the 10-time freeze-thaw expansion rate increases to 1.7%. This shows that after the aluminum powder is coated with aluminum silicate, it can effectively increase the mechanical properties of the solidified body of the cement-based slightly expanding filling grouting material. This may be because the aluminum powder without coating has too high reaction activity, reacts with water to generate a large amount of gas in the early stage of the curing of the cement-based slightly expanding filling grouting material, and the expansion volume is too large when the solidified body is not completely cured, resulting in shrinkage holes or even collapse in the later stage, leading to a significant decrease in the mechanical properties of the solidified body of the cement-based slightly expanding filling grouting material; in Comparative Example 2, the magnesium oxide is not coated with calcium silicate, and the fluidity of Comparative Example 2 slightly decreases, the 28-day compressive strength and the 28-day flexural strength are significantly reduced, and the 28-day shrinkage rate also increases to 1.4%, and the 10-time freeze-thaw expansion rate increases to 1.1%. This shows that after the magnesium oxide is coated with calcium silicate, it can greatly improve the mechanical properties of the solidified body of the cement-based slightly expanding filling grouting material. This may be because after the magnesium oxide is coated with calcium silicate, the reaction rate with the main materials in the cement-based slightly expanding filling grouting material decreases, which can slow down the expansion effect of the magnesium oxide, so that the cement-based slightly expanding filling grouting material undergoes a slight expansion effect mainly in the later stage of curing, and thus can more effectively enhance the enhancement effect of the magnesium oxide on the mechanical properties of the cement-based slightly expanding filling grouting material; in Comparative Example 3, the iron powder is not coated with tung oil, and the fluidity of Comparative Example 3 slightly decreases, and the 28-day compressive strength and the 28-day flexural strength also decrease significantly. The 28-day shrinkage rate also increases to 0.9%, and the 10-time freeze-thaw expansion rate increases to 0.4%. This shows that after the iron powder is coated with tung oil, it can also increase the improvement effect of the iron powder on the mechanical properties of the cement-based slightly expanding filling grouting material. This may be because the coating of tung oil can appropriately slow down the reaction rate of the iron powder with the alkaline components during the curing process of the grouting material, so that the gel generated by the iron powder can more uniformly and fully enter the network body of the silicate cement curing, increasing the density of the solidified body, and thus more effectively improving the mechanical properties of the grouting material solidified body; in Comparative Example 4, the added aluminum powder, magnesium oxide powder and iron powder are not coated, and the fluidity of Comparative Example 4 drops to 388 mm, and the 28-day compressive strength, the 28-day flexural strength, the 28-day shrinkage rate and the 10-time freeze-thaw expansion rate all drop to the worst values. This shows that if these three powders with relatively high reaction activity are not coated, the expansion rate during the curing reaction process is difficult to effectively control, ultimately leading to a sharp deterioration of the mechanical properties of the solidified body of the cement-based slightly expanding filling grouting material.

[0176] As described above, it is only the preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes should be covered within the protection scope of the present invention.

Claims

1. A high-performance cement-based micro-expansion filling grouting material, characterized by: The raw materials of the high-performance cement-based micro-expansion filling grouting material include silicate cement, fly ash, graded aggregate, aluminum silicate-coated aluminum powder, calcium silicate-coated magnesium oxide, tung oil-coated iron powder, calcium formate early strength agent, polycarboxylate water-reducing agent powder, and water; The aluminum silicate-coated aluminum powder is prepared by: drying the aluminum powder, placing it in a dry and anhydrous high-speed dispersing kettle, then adding acetone, vigorously dispersing it evenly, then adding hexamethyldisilazane to the high-speed dispersing kettle, continuing the dispersion reaction until it is completed, adding deionized water to the high-speed dispersing kettle, continuing the dispersion reaction until it is complete, centrifuging, washing the separated solid with anhydrous ethanol, and drying it to obtain the organosilicon-coated aluminum powder, then adding the organosilicon-coated aluminum powder and an aluminum sulfate aqueous solution to the high-speed dispersing kettle, vigorously dispersing it evenly, reducing the dispersion rate, then dropwise adding a sodium metasilicate aqueous solution to the high-speed dispersing kettle, continuing the dispersion reaction until it is complete, filtering and separating, washing the filtered solid with deionized water, and drying it to obtain the aluminum silicate-coated aluminum powder; The calcium silicate-coated magnesium oxide is prepared by adding magnesium oxide powder and a calcium chloride aqueous solution into a high-speed dispersing kettle, vigorously dispersing the powder and then reducing the dispersion rate. Then, a sodium metasilicate aqueous solution is added dropwise into the high-speed dispersing kettle. After the addition is complete, the dispersion reaction is continued until the powder is dispersed and the powder is filtered and separated. The filtered solid is washed with deionized water and dried to obtain the calcium silicate-coated magnesium oxide. The tung oil-coated iron powder is prepared by adding iron powder, distearoyloxyisopropylaluminate, aluminum isopropoxide, and toluene into a high-speed dispersing kettle, vigorously dispersing the iron powder evenly, adding tung oil, continuing to disperse the iron powder evenly, and then feeding the dispersion into a spray dryer for spray drying and granulation to obtain the tung oil-coated iron powder.

2. The high-performance cement-based micro-expansion filling grouting material according to claim 1, characterized in that: The raw material composition of the high-performance cement-based micro-expansive filling grouting material is, in parts by weight, 350-500 parts of Portland cement, 200-350 parts of fly ash, 220-360 parts of graded aggregate, 10-40 parts of aluminum silicate-coated aluminum powder, 15-50 parts of calcium silicate-coated magnesium oxide, 25-60 parts of tung oil-coated iron powder, 10-35 parts of calcium formate early strength agent, 9-20 parts of polycarboxylate water reducer powder, and 250-400 parts of water; The fly ash is Grade II fly ash specified in the national standard GB / T 1596-2005 Fly ash for cement and concrete, and has a particle size of 1 to 90 μm. The graded aggregate is river sand that meets the grading standard, and the grading standard is: the percentage passing through the 4.75mm sieve hole is 100wt%, the percentage passing through the 2.36mm sieve hole is 90-96wt%, the percentage passing through the 1.18mm sieve hole is 70-90wt%, and the percentage passing through the 0.6mm sieve hole is 60-85wt%.

3. The high-performance cement-based micro-expansion filling grouting material according to claim 1, characterized in that: The particle size of the aluminum powder is 0.1-3 μm; In the preparation step of the aluminum powder coated with aluminum silicate, the mass ratio of aluminum powder, acetone, hexamethyldisilazane, and deionized water is 20-50:90-180:9-20:0.3-0.9; In the aluminum sulfate aqueous solution, the mass fraction of aluminum sulfate is 18-28 wt%; In the preparation step of the aluminum powder coated with aluminum silicate, the mass fraction of sodium metasilicate in the sodium metasilicate aqueous solution is 20-33 wt%, and the modulus of sodium metasilicate is 1.5-2.5; The mass ratio of the aluminum powder coated with silicone, the aluminum sulfate aqueous solution, and the sodium metasilicate aqueous solution is 10-45:80-200:50-130.

4. The high-performance cement-based slightly expanding filling grouting material according to claim 1, wherein: The particle size of the magnesium oxide powder is 0.3-2 μm; In the calcium chloride aqueous solution, the mass fraction of calcium chloride is 20-40 wt%; In the preparation step of the magnesium oxide coated with calcium silicate, the mass fraction of sodium metasilicate in the sodium metasilicate aqueous solution is 20-33 wt%, and the modulus of sodium metasilicate is 1.5-2.5; The mass ratio of the magnesium oxide powder, the calcium chloride aqueous solution, and the sodium metasilicate aqueous solution is 20-50:100-250:60-180.

5. The high-performance cement-based slightly expanding filling grouting material according to claim 1, wherein: The particle size of the iron powder is 0.3-4 μm; The mass ratio of the iron powder, aluminum isopropyl dioleate, aluminum isopropoxide, toluene, and tung oil is 20-60:0.5-2:1-4:70-180:9-35.

6. The preparation method of the high-performance cement-based slightly expanding filling grouting material according to claim 1, wherein: According to the raw material composition of the high-performance cement-based slightly expanding filling grouting material in parts by weight, add fly ash, aluminum powder coated with aluminum silicate, magnesium oxide coated with calcium silicate, iron powder coated with tung oil, formate early strength agent, polycarboxylate water reducing agent powder, and half of the weight of water in the formula to a mixer. Under the condition of controlling the stirring rate at 80-130 revolutions per minute, stir and mix for 20-35 minutes, then add Portland cement, graded aggregate, and the other half of the weight of water in the formula, and continue to stir and mix for 10-20 minutes, and then discharge to obtain the high-performance cement-based slightly expanding filling grouting material.

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