A modified calcium oxide expansive grouting material and its preparation method and application

Abstract

The invention discloses a modified calcium oxide expansive grouting material, the raw materials of which include: cement, calcium oxide expansive agent, water-based polyurethane, early strength agent, defoamer, water reducer and water; the mass ratio of cement, calcium oxide expansive agent, water-based polyurethane, early strength agent, defoamer, water reducer and water is 1000:30-90:8-12:50-70:2-4:10-14:500. The raw materials also include: limestone, silica powder, fly ash, sodium alginate, graphene oxide, microbial preparation, urea, calcium lactate; the mass ratio of limestone, silica powder, fly ash, sodium alginate, graphene oxide, microbial preparation, urea, calcium lactate and cement is 20-40:1-3:5-15:1-2:1-3:1-2:1-3:1-2:1000. The invention also discloses a preparation method and application of the modified calcium oxide expansive grouting material.

Description

Technical Field

[0001] The invention relates to the technical field of concrete materials, and in particular to a modified calcium oxide expansive grouting material and a preparation method and application thereof. Background Art

[0002] Cement-based materials are one of the most widely used materials at present, because of their low cost, wide sources, and high adaptability to different geological conditions. They also have controllable setting time and fluidity, which can be artificially adjusted according to specific conditions. Therefore, cement-based grouting materials are widely used in underground engineering construction. However, with the increasing burial depth of tunnel projects, the ground stress gradually increases, the geological conditions become more and more complex, and the reinforcement of fractured rock mass becomes more and more difficult. Commonly used ordinary cement-based grouting materials shrink after solidification, especially in soft rock tunnels with complex geological conditions, the phenomenon of slurry-rock separation often occurs, which greatly affects the reinforcement effect.

[0003] Since cement-based grouting materials have some disadvantages, such as low early strength, long solidification time, and the formation of voids due to hydration shrinkage after cement solidification, resulting in air leakage, etc., adding some admixtures, such as expansion agents, to the grouting slurry to enhance the performance of cement-based materials has become a solution. After adding the expansion agent, the cement slurry will have expansion characteristics, which will improve the mechanical strength and stability of the grouting area. Expansive grouting materials can use the extrusion force generated by their own volume expansion to form a combined reinforcement effect of "extrusion + bonding".

[0004] However, the existing cement-based grouting materials have the following problems in application: although the problems of voids, holes and looseness are solved after grouting, the defects may continue to develop over time, and the problems of voids and hollows are prone to reappear, and the grouting materials can no longer expand to fill these defects, resulting in maintenance failure.

[0005] Based on this, a grouting material is developed that can expand again to fill the voids over time and enhance the mechanical strength of the structure to meet the increasingly stringent needs and quality requirements of underground engineering projects. This has important technical innovation and practical value. Summary of the invention

[0006] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a modified calcium oxide expansive grouting material and a preparation method and application thereof.

[0007] A modified calcium oxide expansive grouting material, the raw materials of which include: cement, calcium oxide expansive agent, waterborne polyurethane, early strength agent, defoamer, water reducer and water; the mass ratio of cement, calcium oxide expansive agent, waterborne polyurethane, early strength agent, defoamer, water reducer and water is 1000:30-90:8-12:50-70:2-4:10-14:500.

[0008] Preferably, the calcium oxide expansive agent refers to a concrete expansive agent that generates calcium hydroxide after hydration when mixed with water and cement. The calcium oxide expansive agent is the latest generation of expansive agents used in the preparation of shrinkage-compensating concrete, and has excellent properties such as high expansion efficiency, small impact on workability and strength, and low sensitivity to temperature and humidity. The expansive agent has the functions of compensating for concrete shrinkage, compacting concrete, and improving concrete impermeability, and can avoid the problems of voids and cracks formed by the solidification shrinkage of cement mortar.

[0009] Preferably, the early strength agent is anhydrous sodium sulfate, which is produced by Tianjin Dengfeng Chemical Reagent Factory. The addition of sodium sulfate can quickly improve the early strength, and the improvement is large, and there is still stable development in the later period, which accelerates the hydration speed and increases the output of hydrates. Sodium sulfate is rich in resources, widely used, and deeply studied, and has a good early strength effect.

[0010] Preferably, the water reducer is a naphthalene-based water reducer or a polycarboxylic acid water reducer. The water reducer can reduce the mixing water consumption while maintaining the slump of cement mortar substantially unchanged. The water reducer added to the cement mortar mixture has a dispersing effect on cement particles, can improve its workability, and achieve the effect of reducing the unit water consumption; under the condition of the unit water consumption remaining unchanged, the fluidity of the cement mortar mixture can be improved, the unit cement consumption can be reduced, and cement can be saved.

[0011] Defoamers can reduce the surface tension of cement mortar, prevent foam formation and improve the quality of mortar.

[0012] Preferably, the raw materials also include: limestone, silica powder, fly ash, sodium alginate, graphene oxide, microbial preparation, urea, calcium lactate; the mass ratio of limestone, silica powder, fly ash, sodium alginate, graphene oxide, microbial preparation, urea, calcium lactate and cement is 20-40:1-3:5-15:1-2:1-3:1-2:1-3:1-2:1000.

[0013] More preferably, the microbial preparation is a urease-producing microorganism, including: Bacillus pasteurianus and Sarcina pasteurianus.

[0014] More preferably, the concentration of Bacillus pasteurianus is 4-8×10 8 cfu / g, the concentration of Sarcina pastoris was 1-3×10 8 cfu / g.

[0015] More preferably, the specific surface area of ​​the silicon powder is 16-20m 2 / g.

[0016] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps: mixing cement, an early strength agent and a calcium oxide expansive agent evenly to obtain a mixture I; mixing a defoamer and a water reducer evenly to obtain a mixture II; introducing the mixture II into water and stirring evenly, then slowly and uniformly adding the mixture I, continuing stirring for 2-4 minutes, and adding waterborne polyurethane and stirring evenly.

[0017] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps:

[0018] S1, mixing cement, early strength agent and calcium oxide expansion agent to obtain mixture I;

[0019] S2, mixing the defoamer and the water reducing agent uniformly to obtain a mixture II;

[0020] S3, mix limestone and silica powder and grind them to a fineness of 150-180 μm 2 / kg, calcined at 1100-1150°C for 20-40min, quenched in air, and crushed to obtain a mixture III;

[0021] S4, adding fly ash, sodium alginate and graphene oxide to water and ultrasonically treating for 1-2 hours at an ultrasonic frequency of 5-12 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 1-2 hours, sieving, calcining at 400-450° C. in a nitrogen atmosphere for 5-12 minutes, cooling to room temperature, adding microbial preparation and stirring for 1-2 hours, and then ultrasonically treating for 1-2 hours at an ultrasonic frequency of 2-8 kHz to obtain mixture IV;

[0022] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 2-4 minutes, then add water-based polyurethane, mixture IV, urea, and calcium lactate and stir evenly to obtain a modified calcium oxide-based expansive grouting material.

[0023] The modified calcium oxide expansive grouting material is used as a grouting reinforcement material.

[0024] Beneficial effects:

[0025] 1. The present invention adds silicon powder to limestone for compounding and calcining at high temperature, which can not only effectively reduce the calcination temperature of limestone and effectively avoid overburning of calcium oxide, but also has fast expansion speed and high expansion efficiency.

[0026] 2. The present invention adopts fly ash and graphene oxide compound, and the lamellar graphene oxide is dispersed in the gaps of porous fly ash, solidified into a film with sodium alginate, and compounded with mixture III and calcined to load the microorganisms, thereby providing an environment free from damage for the microorganisms and improving the survival time and activity of the microorganisms.

[0027] The silica powder contained in mixture IV has low initial cement hydration activity and contributes little to the compressive strength of the material in the early stage. As the curing time increases, the silica powder begins to participate in the hydration reaction. Silica powder has a good volcanic ash effect and can effectively reduce the porosity. It can also react with the cement hydration product calcium hydroxide to form calcium silicate gel, increase gelling properties, improve interface structure, reduce the amount of calcium hydroxide and crystal orientation, make the structure denser, and thus improve its later compressive strength.

[0028] At the same time, experiments have found that the present application can still produce effective expansion in a dry environment, which plays a good compensatory role in the later drying shrinkage of cement concrete. As time goes by, microorganisms (especially Bacillus pasteurianus and Sarcina pasteurianus) secrete biological enzymes to decompose urea, calcium lactate, etc., and generate calcium carbonate crystals with calcium ions in the system, which further effectively consolidates the surrounding environment, can expand again to fill the gaps, and can further enhance the mechanical properties.

[0029] 3. Compared with traditional polymer grouting materials, the present invention not only has high mechanical strength, higher compressive strength and flexural strength, but also can produce secondary expansion, which effectively solves the shrinkage problem of traditional materials and the problem that the repaired defects will expand again and cannot be cured.

[0030] 4. The present invention has high strength, no voids, no shrinkage and no cracking during use. By optimizing the material components, the performance and quality of cement mortar are greatly improved. At the same time, it can meet the needs of self-expanding grouting materials with different expansion rates, effectively prevent mortar and concrete from cracking, and improve its durability such as anti-seepage, anti-erosion, and anti-pollution. Its preparation method is simple and the construction is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a comparison chart of the fluidity of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3.

[0032] Figure 2 It is a comparison diagram of the deformation curves of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3 in a dry environment, wherein a positive value indicates that the specimen has undergone expansion deformation under dry conditions, while a negative value indicates that the specimen has undergone contraction deformation under dry conditions.

[0033] Figure 3 It is a comparison chart of the vertical expansion rates of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3.

[0034] Figure 4 It is a comparison chart of the restricted expansion rates of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3.

[0035] Figure 5 It is a comparison chart of the compressive strength of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0036] The present invention will be further explained below in conjunction with specific embodiments.

[0037] The following calcium oxide expansion agent and polycarboxylate water reducer PCA-I were purchased from Jiangsu Bote New Materials Co., Ltd.; the defoaming agent was the Zhongyan ZY-DF3 defoaming agent produced by Zhongyan Technology; the naphthalene-based water reducer was the FDN-A water reducer produced by Laiwu Ruiteng New Building Materials Technology Co., Ltd.

[0038] Example 1

[0039] A modified calcium oxide expansive grouting material, whose raw materials include: 1000kg of P.O42.5 cement, 30kg of calcium oxide expansive agent, 8kg of water-based polyurethane, 50kg of anhydrous sodium sulfate, 2kg of defoaming agent, 10kg of water reducing agent, and 500kg of water.

[0040] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps: mixing P.O42.5 cement, anhydrous sodium sulfate and a calcium oxide expansive agent evenly to obtain a mixture I; mixing a defoamer and a water reducer evenly to obtain a mixture II; introducing the mixture II into water and stirring evenly, then slowly and uniformly adding the mixture I, continuing stirring for 2 minutes, and adding waterborne polyurethane and stirring evenly.

[0041] Example 2

[0042] A modified calcium oxide expansive grouting material, whose raw materials include: 1000kg of P.O42.5 cement, 90kg of calcium oxide expansive agent, 12kg of waterborne polyurethane, 70kg of anhydrous sodium sulfate, 4kg of defoamer, 14kg of water reducing agent and 500kg of water.

[0043] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps: mixing P.O42.5 cement, anhydrous sodium sulfate and a calcium oxide expansive agent evenly to obtain a mixture I; mixing a defoamer and a water reducer evenly to obtain a mixture II; introducing the mixture II into water and stirring evenly, then slowly and uniformly adding the mixture I, continuing stirring for 4 minutes, and adding waterborne polyurethane and stirring evenly.

[0044] Example 3

[0045] A modified calcium oxide expansive grouting material, whose raw materials include: 1000kg of P.O42.5 cement, 60kg of calcium oxide expansive agent, 10kg of water-based polyurethane, 60kg of anhydrous sodium sulfate, 3kg of defoaming agent, 12kg of water reducing agent, and 500kg of water.

[0046] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps: mixing P.O42.5 cement, anhydrous sodium sulfate and a calcium oxide expansive agent evenly to obtain a mixture I; mixing a defoamer and a water reducer evenly to obtain a mixture II; introducing the mixture II into water and stirring evenly, then slowly and uniformly adding the mixture I, continuing stirring for 3 minutes, and adding waterborne polyurethane and stirring evenly.

[0047] Example 4

[0048] A modified calcium oxide expansive grouting material, whose raw materials include: 1000kg of P.O42.5 cement, 55kg of anhydrous sodium sulfate, 80kg of calcium oxide expansive agent, 2.5kg of defoamer, 13kg of polycarboxylic acid water reducer PCA-I, 20kg of limestone, 3kg of silica fume, 5kg of Class III F fly ash, 2kg of sodium alginate, 1kg of graphene oxide, 2kg of urease-producing microbial preparation, 9kg of water-based polyurethane, 3kg of urea, 1kg of calcium lactate, and 500kg of water.

[0049] Urease-producing microbial preparations include: concentration of 8×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 1×10 8 cfu / g of Sarcina pastoris.

[0050] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps:

[0051] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and calcium oxide expansion agent to obtain mixture I;

[0052] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0053] S3, mix limestone and silica powder and grind them to a fineness of 180 μm. 2 / kg, calcined at 1100℃ for 40min, quenched in air, and crushed to obtain mixture III;

[0054] S4, adding Class III F fly ash, sodium alginate, and graphene oxide to water and ultrasonically treating for 1 hour at an ultrasonic frequency of 12 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III, mixing and grinding for 1 hour, sieving, calcining at 450° C. in a nitrogen atmosphere for 5 minutes, cooling to room temperature, adding a microbial preparation and stirring for 2 hours, and then ultrasonically treating for 1 hour at an ultrasonic frequency of 8 kHz to obtain a mixture IV;

[0055] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 2 minutes, then add water-based polyurethane, mixture IV, urea, and calcium lactate and stir evenly to obtain a modified calcium oxide-based expansive grouting material.

[0056] Example 5

[0057] A modified calcium oxide expansive grouting material, whose raw materials include: 1000kg of P.O42.5 cement, 65kg of anhydrous sodium sulfate, 40kg of calcium oxide expansive agent, 3.5kg of defoaming agent, 11kg of polycarboxylic acid water reducer PCA-I, 40kg of limestone, 1kg of silica fume, 15kg of Class III F fly ash, 1kg of sodium alginate, 3kg of graphene oxide, 1kg of urease-producing microbial preparation, 11kg of water-based polyurethane, 1kg of urea, 2kg of calcium lactate, and 500kg of water.

[0058] Urease-producing microbial preparations include: a concentration of 4×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 3×10 8 cfu / g of Sarcina pastoris.

[0059] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps:

[0060] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and calcium oxide expansion agent to obtain mixture I;

[0061] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0062] S3, mix limestone and silica powder and grind them to a fineness of 150 μm. 2 / kg, calcined at 1150℃ for 20min, quenched in air, and crushed to obtain mixture III;

[0063] S4, adding Class III F fly ash, sodium alginate, and graphene oxide to water and ultrasonically treating for 2 hours at an ultrasonic frequency of 5 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 2 hours, sieving, calcining at 400° C. in a nitrogen atmosphere for 12 minutes, cooling to room temperature, adding a microbial preparation and stirring for 1 hour, and then ultrasonically treating for 2 hours at an ultrasonic frequency of 2 kHz to obtain a mixture IV;

[0064] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 4 minutes, then add water-based polyurethane, mixture IV, urea and calcium lactate and stir evenly to obtain a modified calcium oxide expansive grouting material.

[0065] Example 6

[0066] A modified calcium oxide expansive grouting material, the raw materials of which include: 1000kg of P.O42.5 cement, 58kg of anhydrous sodium sulfate, 70kg of calcium oxide expansive agent, 2.8kg of defoamer, 12.5kg of polycarboxylate water reducer PCA-I, 25kg of limestone, and a specific surface area of ​​20m 2 / g silica powder 1.5kg, Class III F fly ash 12kg, sodium alginate 1.3kg, graphene oxide 2.5kg, urease-producing microbial preparation 1.2kg, water-based polyurethane 10.5kg, urea 1.5kg, calcium lactate 1.7kg, water 500kg.

[0067] Urease-producing microbial preparations include: a concentration of 4×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 3×10 8 cfu / g of Sarcina pastoris.

[0068] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps:

[0069] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and calcium oxide expansion agent to obtain mixture I;

[0070] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0071] S3, mix limestone and silica powder and grind them into a fineness of 160 μm. 2 / kg, calcined at 1130℃ for 25min, quenched in air, and crushed to obtain mixture III;

[0072] S4, adding Class III F fly ash, sodium alginate, and graphene oxide to water and ultrasonically treating for 100 minutes at an ultrasonic frequency of 6 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 100 minutes, sieving, calcining at 420° C. in a nitrogen atmosphere for 9 minutes, cooling to room temperature, adding a microbial preparation and stirring for 80 minutes, and then ultrasonically treating for 100 minutes at an ultrasonic frequency of 4 kHz to obtain a mixture IV;

[0073] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 3.5 min, then add water-based polyurethane, mixture IV, urea and calcium lactate and stir evenly to obtain a modified calcium oxide-based expansive grouting material.

[0074] Example 7

[0075] A modified calcium oxide expansive grouting material, the raw materials of which include: 1000kg of P.O42.5 cement, 62kg of anhydrous sodium sulfate, 50kg of calcium oxide expansive agent, 3.2kg of defoamer, 11.5kg of polycarboxylate water reducer PCA-I, 35kg of limestone, and a specific surface area of ​​16m 2 / g silica powder 2.5kg, Class III F fly ash 8kg, sodium alginate 1.7kg, graphene oxide 1.5kg, urease-producing microbial preparation 1.8kg, water-based polyurethane 9.5kg, urea 2.5kg, calcium lactate 1.3kg, water 500kg.

[0076] Urease-producing microbial preparations include: concentration of 8×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 1×10 8 cfu / g of Sarcina pastoris.

[0077] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps:

[0078] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and calcium oxide expansion agent to obtain mixture I;

[0079] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0080] S3, mix limestone and silicon powder and grind them into a fineness of 170 μm. 2 / kg, calcined at 1110℃ for 35min, quenched in air, and crushed to obtain mixture III;

[0081] S4, adding Class III F fly ash, sodium alginate, and graphene oxide to water and ultrasonically treating for 80 minutes at an ultrasonic frequency of 10 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 80 minutes, sieving, calcining at 445° C. in a nitrogen atmosphere for 7 minutes, cooling to room temperature, adding a microbial preparation and stirring for 100 minutes, and then ultrasonically treating for 80 minutes at an ultrasonic frequency of 6 kHz to obtain a mixture IV;

[0082] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 2.5 min, then add water-based polyurethane, mixture IV, urea and calcium lactate and stir evenly to obtain a modified calcium oxide expansive grouting material.

[0083] Example 8

[0084] A modified calcium oxide expansive grouting material, the raw materials of which include: 1000kg of P.O42.5 cement, 60kg of anhydrous sodium sulfate, 60kg of calcium oxide expansive agent, 3kg of defoamer, 12kg of polycarboxylate water reducer PCA-I, 30kg of limestone, and a specific surface area of ​​18.7m 2 / g silica fume 2kg, Class III F fly ash 10kg, sodium alginate 1.5kg, graphene oxide 2kg, urease-producing microbial preparation 1.5kg, water-based polyurethane 10kg, urea 2kg, calcium lactate 1.5kg, water 500kg.

[0085] Urease-producing microbial preparations include: concentration of 6×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 2×10 8 cfu / g of Sarcina pastoris.

[0086] The preparation method of the modified calcium oxide expansive grouting material comprises the following steps:

[0087] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and calcium oxide expansion agent to obtain mixture I;

[0088] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0089] S3, mix limestone and silica powder and grind them to a fineness of 165 μm. 2 / kg, calcined at 1120℃ for 30min, quenched in air, and crushed to obtain mixture III;

[0090] S4, adding Class III F fly ash, sodium alginate, and graphene oxide to water and ultrasonically treating for 90 minutes at an ultrasonic frequency of 8 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 90 minutes, sieving, calcining at 440° C. in a nitrogen atmosphere for 8 minutes, cooling to room temperature, adding a microbial preparation and stirring for 90 minutes, and then ultrasonically treating for 90 minutes at an ultrasonic frequency of 5 kHz to obtain a mixture IV;

[0091] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 3 minutes, then add water-based polyurethane, mixture IV, urea, and calcium lactate and stir evenly to obtain a modified calcium oxide-based expansive grouting material.

[0092] Comparative Example 1

[0093] An expansive grouting material, the raw materials of which include: 1000 kg of P.O42.5 cement, 60 kg of anhydrous sodium sulfate, 60 kg of UEA expansion agent (purchased from Kunming Baiyi Building Materials Manufacturing Co., Ltd.), 3 kg of defoamer, 12 kg of polycarboxylate water-reducing agent PCA-I, 30 kg of limestone, and a specific surface area of ​​18.7 m 2 / g silica fume 2kg, Class III F fly ash 10kg, sodium alginate 1.5kg, graphene oxide 2kg, urease-producing microbial preparation 1.5kg, water-based polyurethane 10kg, urea 2kg, calcium lactate 1.5kg, water 500kg.

[0094] Urease-producing microbial preparations include: concentration of 6×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 2×10 8 cfu / g of Sarcina pastoris.

[0095] The preparation method of the above-mentioned expansive grouting material comprises the following steps:

[0096] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and UEA expansion agent to obtain mixture I;

[0097] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0098] S3, mix limestone and silica powder and grind them to a fineness of 165 μm. 2 / kg, calcined at 1120℃ for 30min, quenched in air, and crushed to obtain mixture III;

[0099] S4, adding Class III F fly ash, sodium alginate, and graphene oxide to water and ultrasonically treating for 90 minutes at an ultrasonic frequency of 8 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 90 minutes, sieving, calcining at 440° C. in a nitrogen atmosphere for 8 minutes, cooling to room temperature, adding a microbial preparation and stirring for 90 minutes, and then ultrasonically treating for 90 minutes at an ultrasonic frequency of 5 kHz to obtain a mixture IV;

[0100] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 3 minutes, then add water-based polyurethane, mixture IV, urea and calcium lactate and stir evenly to obtain an expansive grouting material.

[0101] Comparative Example 2

[0102] An expansive grouting material, whose raw materials include: 1000kg of P.O42.5 cement, 60kg of anhydrous sodium sulfate, 60kg of calcium oxide expansive agent, 3kg of defoaming agent, 12kg of polycarboxylic acid water reducer PCA-I, 30kg of limestone, 10kg of Class III F fly ash, 1.5kg of sodium alginate, 2kg of graphene oxide, 1.5kg of urease-producing microbial preparation, 10kg of water-based polyurethane, 2kg of urea, 1.5kg of calcium lactate, and 500kg of water.

[0103] Urease-producing microbial preparations include: concentration of 6×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 2×10 8 cfu / g of Sarcina pastoris.

[0104] The preparation method of the above-mentioned expansive grouting material comprises the following steps:

[0105] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and calcium oxide expansion agent to obtain mixture I;

[0106] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0107] S3, ball grind the limestone to a fineness of 165m 2 / kg, calcined at 1120℃ for 30min, quenched in air, and crushed to obtain mixture III;

[0108] S4, adding Class III F fly ash, sodium alginate, and graphene oxide to water and ultrasonically treating for 90 minutes at an ultrasonic frequency of 8 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 90 minutes, sieving, calcining at 440° C. in a nitrogen atmosphere for 8 minutes, cooling to room temperature, adding a microbial preparation and stirring for 90 minutes, and then ultrasonically treating for 90 minutes at an ultrasonic frequency of 5 kHz to obtain a mixture IV;

[0109] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 3 minutes, then add water-based polyurethane, mixture IV, urea and calcium lactate and stir evenly to obtain an expansive grouting material.

[0110] Comparative Example 3

[0111] An expansive grouting material, the raw materials of which include: 1000kg of P.O42.5 cement, 60kg of anhydrous sodium sulfate, 60kg of calcium oxide expansion agent, 3kg of defoamer, 12kg of polycarboxylate water reducer PCA-I, 30kg of limestone, and a specific surface area of ​​18.7m 2 / g silica fume 2kg, Class III F fly ash 10kg, sodium alginate 1.5kg, graphene oxide 2kg, urease-producing microbial preparation 1.5kg, water-based polyurethane 10kg, urea 2kg, calcium lactate 1.5kg, water 500kg.

[0112] Urease-producing microbial preparations include: concentration of 6×10 8 cfu / g of Bacillus pasteurianus, with a concentration of 2×10 8 cfu / g of Sarcina pastoris.

[0113] The preparation method of the above-mentioned expansive grouting material comprises the following steps:

[0114] S1, mixing P.O42.5 cement, anhydrous sodium sulfate and calcium oxide expansion agent to obtain mixture I;

[0115] S2, mixing the defoamer and the polycarboxylate water reducer PCA-I to obtain a mixture II;

[0116] S3, mix limestone and silica powder and grind them to a fineness of 165 μm. 2 / kg, calcined at 1120℃ for 30min, quenched in air, and crushed to obtain mixture III;

[0117] S4, grinding the mixture III for 90 minutes, sieving, calcining at 440° C. for 8 minutes in a nitrogen atmosphere, cooling to room temperature, adding the microbial preparation and stirring for 90 minutes, and then ultrasonically treating for 90 minutes at an ultrasonic frequency of 5 kHz to obtain a mixture IV;

[0118] S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 3 minutes, then add water-based polyurethane, mixture IV, urea and calcium lactate and stir evenly to obtain an expansive grouting material.

[0119] The fluidity of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3 was measured with reference to GB / T 50448-2015 "Technical Specifications for Application of Cement-based Grouting Materials". The test instrument used a truncated cone circular mold and was placed on a horizontal test bench. The truncated cone circular mold was lifted steadily, and the grouting material flowed freely without disturbance until it stopped. The maximum diffusion diameter of the bottom surface and its vertical diameter were measured with a ruler, and the average value was calculated as the initial value of the fluidity. The fluidity was measured again after 30 minutes.

[0120] like Figure 1 As shown, except for Example 3, the fluidity of the other groups of samples meets the requirements of Class II cement-based grouting materials in GB / T 50448-2015, has good workability, and can be widely used in tunnel vault grouting and other work occasions. The 0min fluidity and 30min fluidity of the expansive grouting material obtained in Example 8 are the highest.

[0121] The expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3 were directly cured in a dry shrinkage environment at a temperature of 20±2°C and a relative humidity of 60±5% after slurry molding. After 24 hours, the molds were demolded and the initial length was measured, as well as the length of the specimens at different curing ages.

[0122] like Figure 2 As shown, the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 2-3 can produce obvious expansion deformation in the early stage of drying and curing, and have a significant compensatory effect on the later shrinkage; while Example 8, on the one hand, uses silicon powder to be added to limestone, which can effectively reduce the porosity, increase the cementitiousness, make the structure denser, and reduce the shrinkage and deformation of the concrete itself, and on the other hand, uses microorganisms to secrete biological enzymes to decompose urea, calcium lactate, etc., and then generate calcium carbonate crystals with calcium ions in the system, which further effectively consolidates the surrounding environment and can expand again to fill the gaps, thereby maximizing the expansion deformation of Example 8.

[0123] While in Comparative Example 1, UEA expansion agent is used to make the obtained expansive grouting material have poor shrinkage compensation effect when cured in a dry environment. However, in Comparative Example 1, microorganisms are also used to secrete biological enzymes to decompose urea, calcium lactate, etc., so that the deformation amount in the later stage is slightly increased.

[0124] The vertical expansion rate of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3 was measured with reference to GB / T 50081-2019 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0125] like Figure 3 As shown, except for Example 3, the vertical expansion rates of the other groups all meet the requirements of GB / T50081-2019, and the 3h vertical expansion rate of the expansive grouting material obtained in Example 8 is the highest.

[0126] The limiting expansion rates of the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3 were measured with reference to Test Method B in Appendix A of GB / T 23439-2017 "Concrete Expansion Agents".

[0127] like Figure 4 As shown, the restricted expansion rate of each group is greater than that specified in GB / T 23439-2017, and the expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 2-3 still show large expansion deformation after being cured in water for 7 days and then dried in air for 21 days. The restricted expansion rate of the expansive grouting material obtained in Example 8 is always the largest, indicating that the expansive grouting material obtained in the present invention has a large restricted expansion efficiency in a water-cured environment, and still has a large effective expansion in a dehydrated and dry environment.

[0128] The expansive grouting materials obtained in Example 3, Example 8 and Comparative Examples 1-3 were slurry-formed and tested with reference to GB / T 50081-2019 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete". Each group of grouting materials was poured into a test mold and allowed to stand until the slurry initially solidified, and then the excess slurry on the surface was scraped off. After the specimens were demoulded, they were placed in a standard curing room with a temperature of 20±2°C and a relative humidity of ≥90% for curing for 1d, 3d and 28d, and their compressive strength was measured using a compressive strength testing machine.

[0129] like Figure 2 As shown, except for Example 3, the compressive strengths of the remaining groups of samples all meet the requirements of Class II cement-based grouting materials in GB / T 50448-2015, and the compressive strength of the expansive grouting material obtained in Example 8 is always the highest, and is most suitable for working occasions such as tunnel vault mold grouting.

[0130] The present application believes that the above experimental results are due to the fact that the present invention adds silicon powder to limestone for compounding, and after high-temperature calcination, it can not only effectively reduce the calcination temperature of limestone, effectively avoid the overburning of calcium oxide, but also has a fast expansion speed and high expansion efficiency. At the same time, fly ash is compounded with graphene oxide, and the lamellar graphene oxide is dispersed in the porous fly ash gap, solidified into a film with sodium alginate, and compounded and calcined with mixture III to load microorganisms, provide an environment for microorganisms to be protected from invasion, and improve the survival time and activity of microorganisms. However, the silicon powder contained in mixture IV has low cement initial hydration activity, and its contribution to the compressive strength of the material is small in the early stage. As the curing time increases, silicon powder begins to participate in the hydration reaction. Silicon powder has a good volcanic ash effect, can effectively reduce porosity, and can also form calcium silicate gel with cement hydration product calcium hydroxide, increase gelling properties, improve interface structure, reduce the amount of calcium hydroxide and crystal orientation, make the structure more compact, and thus improve its later compressive strength. At the same time, as time goes by, microorganisms (especially Bacillus pasteurianus and Sarcina pasteurianus) secrete biological enzymes to decompose urea, calcium lactate, etc., and form calcium carbonate crystals with calcium ions in the system, which further effectively consolidate the surrounding environment, can expand again to fill the gaps, and can further enhance the mechanical properties.

[0131] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A modified calcium oxide expansive grouting material, characterized in that: Its raw materials include: cement, calcium oxide expansion agent, water-based polyurethane, early strength agent, defoamer, water reducer and water; the mass ratio of cement, calcium oxide expansion agent, water-based polyurethane, early strength agent, defoamer, water reducer and water is 1000:30-90:8-12:50-70:2-4:10-14:500; Its raw materials also include: limestone, silica fume, fly ash, sodium alginate, graphene oxide, microbial preparation, urea, calcium lactate; the mass ratio of limestone, silica fume, fly ash, sodium alginate, graphene oxide, microbial preparation, urea, calcium lactate and cement is 20-40:1-3:5-15:1-2:1-3:1-2:1-3:1-2:1000; The limestone and the silicon powder are compounded and calcined at high temperature before being used as a mixture.

2. The modified calcium oxide expansive grouting material according to claim 1, characterized in that: The early strength agent is anhydrous sodium sulfate.

3. The modified calcium oxide expansive grouting material according to claim 1, characterized in that: The water reducer is a naphthalene-based water reducer or a polycarboxylic acid water reducer.

4. The modified calcium oxide expansive grouting material according to claim 1, characterized in that: The microbial preparations are urease-producing microorganisms, including Bacillus pasteurianus and Sarcina pasteurianus.

5. The modified calcium oxide expansive grouting material according to claim 4, characterized in that: The concentration of Bacillus pasteurianus is 4-8×10 8 cfu / g, the concentration of Sarcina pastoris was 1-3×10 8 cfu / g.

6. The modified calcium oxide expansive grouting material according to claim 1, characterized in that: The specific surface area of ​​silicon powder is 16-20m 2 / g.

7. A method for preparing the modified calcium oxide expansive grouting material according to any one of claims 1 to 6, characterized in that: The steps include: S1, mixing cement, early strength agent and calcium oxide expansion agent to obtain mixture I; S2, mixing the defoamer and the water reducing agent uniformly to obtain a mixture II; S3, mix limestone and silica powder and grind them to a fineness of 150-180 μm 2 / kg, calcined at 1100-1150°C for 20-40min, quenched in air, and crushed to obtain a mixture III; S4, adding fly ash, sodium alginate and graphene oxide to water and ultrasonically treating for 1-2 hours at an ultrasonic frequency of 5-12 kHz, adding calcium chloride solution dropwise thereto under stirring, continuing stirring, filtering, washing, drying, adding mixture III and mixing and grinding for 1-2 hours, sieving, calcining at 400-450° C. in a nitrogen atmosphere for 5-12 minutes, cooling to room temperature, adding microbial preparation and stirring for 1-2 hours, and then ultrasonically treating for 1-2 hours at an ultrasonic frequency of 2-8 kHz to obtain mixture IV; S5. Pour mixture II into water and stir evenly, add mixture I at a uniform speed and continue stirring for 2-4 minutes, then add water-based polyurethane, mixture IV, urea, and calcium lactate and stir evenly to obtain a modified calcium oxide-based expansive grouting material.

8. Use of the modified calcium oxide expansive grouting material as claimed in any one of claims 1 to 6 as a grouting reinforcement material.

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