A highly diffusible micro-crack rock interface enhanced grouting material and preparation method thereof

Abstract

The invention discloses a highly diffusible microcrack rock interface enhanced grouting material and a preparation method thereof, and relates to the field of underground engineering broken rock reinforcement, wherein the raw materials of the grouting material include the following components: a cementitious material, an interface enhancer and a modified admixture; wherein the cementitious material includes the following components: ultrafine silicate cement; the raw materials of the interface enhancer include the following components: alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran and ammonium chloride. The interface enhancer of the invention modifies the grouting material, and when cement particles are blocked by microcracks, the interface enhancement component can further penetrate into the microcracks, thereby improving the diffusion performance of the grouting material, and solving the problem of poor diffusivity of suspension type grouting materials such as cement in microcrack rock mass in the prior art.

Description

Technical Field

[0001] The invention relates to the field of underground engineering broken rock mass reinforcement, and in particular to a highly diffusible micro-crack rock mass interface reinforcement grouting material and a preparation method thereof. Background Art

[0002] In the construction process of engineering projects such as transportation tunnels and mineral resource development, unfavorable geological conditions such as broken rock mass are often encountered. In particular, when tunnel excavation is carried out, micro-cracked broken rock mass conditions are particularly common, which has caused great obstacles to engineering construction. At present, the common solution for micro-cracked broken rock mass is to use grouting technology to reinforce the broken rock mass.

[0003] Grouting materials are the key factors affecting the effect of grouting technology. Inorganic suspension grouting materials represented by ordinary cement-based slurry are the most widely used grouting materials at this stage. However, due to their large particle size and easy shrinkage, these grouting materials have poor diffusion, poor reinforcement effect between the grouting materials and the rock mass, and poor anti-seepage effect.

[0004] Patent "CN107619236 A" uses a grouting material composed of ultrafine cement, auxiliary cementitious materials, high-performance composite regulators, and viscous polymers for the treatment of micro-cracked rock and soil reinforcement, but the slurry does not have secondary permeability, and the expansive substances generated by the reaction of alum, aluminum sulfate and other substances in the high-performance composite regulator with gypsum are easy to damage the rock and soil body, and the reaction rate is fast, and the expansive substances generated cannot penetrate into the micro-cracked rock mass in time. Patent "CN118221389 A" prepares microcapsule-modified high-bonding strength grouting materials, and improves the bonding strength through the group characteristics of styrene-acrylic emulsion, but its solid particle structure has poor adaptability in the reinforcement of micro-cracked rock mass. Patent "CN118420270A" prepares mining grouting materials with ultrafine cement, talcum powder, fly ash, hydroxypropyl methylcellulose, water reducer, defoamer, but cellulose will significantly increase the consistency of the slurry and reduce the diffusion performance of the slurry in the rock mass. Summary of the invention

[0005] The purpose of the present invention is to provide a highly diffusible micro-crack rock interface reinforcement grouting material and a preparation method thereof, so as to improve the diffusion performance of the grouting material and the reinforcement effect on the micro-cracked broken rock mass.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A highly diffusible micro-crack rock interface reinforcement grouting material, the raw materials of the grouting material include the following components:

[0008] Cementitious materials, interface enhancers and modified admixtures;

[0009] Wherein, the cementitious material comprises the following components: ultrafine silicate cement;

[0010] The raw materials of the interface enhancer include the following components: alkyl tertiary amine dihydrogen phosphate, beta-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran and ammonium chloride.

[0011] In the present technical solution, the cementitious material is used as the basic raw material of the grouting material, which can transform the grouting material from a semi-liquid state to a solid state, thereby achieving the reinforcement of the rock mass. Among them, ultrafine silicate cement is the core component of the cementitious material. When it is mixed with water, a hydration reaction will occur to generate products such as CSH gel and calcium hydroxide. After these hydration products accumulate to a saturated state in the solution, they will gradually precipitate and harden, so that the grouting material can reach sufficient hardness and strength. Ultrafine silicate cement can also meet the injectability of grouting materials in micro-cracked rock mass by virtue of its tiny particle size characteristics, ensuring the basic diffusion and filling properties of the material. In some embodiments, the ultrafine silicate cement uses P·O 42.5 ultrafine silicate cement. P·O 42.5 ultrafine silicate cement has a higher strength grade and can improve the reinforcement effect on the rock mass. The interface enhancer can improve the bonding performance and anti-seepage effect of the grouting material. Specifically, when the grouting material is injected into the rock mass fissure, the interface enhancer will release free hydrogen phosphate, and the free hydrogen phosphate will chelate with the free calcium ions released by the hydration of ultrafine silicate cement to form metastable calcium hydrogen phosphate; the metastable calcium hydrogen phosphate is further converted into stable hydroxyapatite crystals and filled in the tiny cracks of the rock mass, thereby improving the interfacial bonding strength between the grouting material and the rock mass and the overall anti-seepage effect of the broken rock mass. At the same time, the components of the interface enhancer in the present invention are soluble in water. When the grouting material is injected into the rock mass fissure, if the crack width is too small, it is possible to cause the suspended particles in the grouting material to be blocked and unable to diffuse downward. At this time, the interface enhancer in the form of a solution can penetrate into these microcracks under the carrying action of water, and the above reaction occurs to reinforce the rock mass. This characteristic effectively improves the diffusion performance of the grouting material. The modified admixture is used as an auxiliary agent to improve the fluidity of the grouting material.

[0012] As a preferred embodiment, the raw materials of the interface enhancer also include deionized water and potassium octadecenoate, wherein the weight ratio of deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran, ammonium chloride and potassium octadecenoate is 180~200:80~115:0.5~3:2.7~5.5:190~220:50~95:0.36~0.68.

[0013] In the technical solution, the hydrophobic group and the hydrophilic group in potassium octadecenoate can improve the dispersibility of the interface enhancer in the grouting material, which is beneficial to improving the construction efficiency.

[0014] As a preferred embodiment, the components of the cementitious material further include bismuthinite powder, wherein the weight ratio of the ultrafine silicate cement to the bismuthinite powder is 82-95:5-18.

[0015] In the present technical solution, bismuthinite is a sulfide mineral of the orthorhombic system, the molecular bonds on its cleavage plane are weak, and it is easy to break and dissociate. The bismuthinite powder formed by grinding is hydrophobic and can enhance the anti-seepage performance of the grouting material.

[0016] In some embodiments, the fineness of ultrafine silicate cement is 700-900 mesh, and the fineness of bismuthinite powder is 800-1200 mesh. The smaller particle size enables them to better penetrate into the cracks of the rock mass, helping to form a tight reinforcement layer and improve the overall stability of the rock mass.

[0017] As a preferred embodiment, the raw materials of the modified admixture include the following components: green mud and ammonium dihydrogen phosphate.

[0018] In this technical solution, green mud belongs to the papermaking and printing industry waste listed in the "Solid Waste Classification and Code Catalog", with the waste code: 221-006-S15. It is green mud from the causticizing section in the alkali recovery section, and its main component is calcium carbonate. The present invention uses green mud as a raw material to prepare a modified admixture, which is an effective way to utilize solid waste resources.

[0019] Furthermore, the weight ratio of green mud to diammonium phosphate is 83-110:68-76.

[0020] As a preferred embodiment, the raw materials of the modified admixture also include deionized water, N,N-dimethylformamide and polyoxypropylene glycerol polyether, wherein the weight ratio of deionized water, green mud, diammonium phosphate, N,N-dimethylformamide and polyoxypropylene glycerol polyether is 350~500:83~110:68~76:63~70:15~25.

[0021] In the present technical solution, N,N-dimethylformamide has both a hydrophilic formamide group and a hydrophobic methyl group, which can make the bismuthinite powder evenly distributed in the slurry; the polyoxypropylene glycerol polyether molecules can be arranged on the interface between the bubbles and the liquid inside the slurry, so that the stability of the bubbles is reduced until they burst, which can make the matrix of the grouting material more compact after solidification, thereby enhancing the reinforcement and anti-seepage effects.

[0022] As a preferred embodiment, the weight ratio of the gelling material, the interface enhancer and the modified admixture is 80-120:4.6-7.3:1.5-2.3.

[0023] The present invention also provides a method for preparing a highly diffusible micro-crack rock interface enhanced grouting material, the method comprising:

[0024] preparing the gelling material;

[0025] preparing the interface enhancer;

[0026] preparing the modified admixture;

[0027] Mixing the gelling material, the interface enhancer and the modified admixture with water to obtain the grouting material;

[0028] Wherein, preparing the interface enhancer comprises:

[0029] Deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine and 4-cyanovaleric acid are transferred into a hydrothermal reaction kettle, and the temperature is raised to 50-57° C. to react to obtain a hydrothermal reaction mother liquor; in some embodiments, the reaction time is 90-120 min.

[0030] The mother liquid of the hydrothermal reaction is poured into tetrahydrofuran for precipitation to obtain an intermediate precipitation product; in some embodiments, after the hydrothermal reaction is poured into tetrahydrofuran, precipitation is carried out for 10 to 15 minutes.

[0031] The intermediate precipitate product is dried and ground to obtain a powder product. In some embodiments, the intermediate precipitate product is dried in a forced air drying oven at 45-60° C. for 120-150 min, and then crushed and ground to obtain a powder product.

[0032] In the technical solution, the alkyl tertiary amine dihydrogen phosphate (chemical formula: ) is a salt compound formed by the combination of alkyl tertiary amine and dihydrogen phosphate ion. The alkyl tertiary amine part is a quaternary ammonium salt with a positive charge, in which the nitrogen atom is connected to the alkyl group to form a stable positive ion. The dihydrogen phosphate part is a negatively charged ion, in which the phosphorus atom is connected to the oxygen atom by a covalent bond and carries a hydrogen atom and an additional negative charge.

[0033] In the present invention, the preparation principle of the interface enhancer is: the alkyl tertiary amine dihydrogen phosphate and β-hydroxyalanine are polymerized under the action of 4-cyanovaleric acid to generate a product " ", the specific chemical reaction formula is as follows:

[0034] ;

[0035] After the hydrothermal reaction mother liquor is poured into tetrahydrofuran, the tetrahydrofuran can convert the product into a precipitate, which is convenient for preparing it into a solid powder in the subsequent process for easy transportation and storage.

[0036] In the present invention, when the grouting material is injected into the rock mass fissure, the polymerized product in the interface enhancer " "It gradually hydrolyzes and undergoes a replacement reaction with ammonium chloride to release free hydrogen phosphate and β-hydroxyalanine. The free hydrogen phosphate chelates with calcium ions to form calcium hydrogen phosphate; under the promotion of β-hydroxyalanine, the calcium hydrogen phosphate is converted into hydroxyapatite crystals. It should be noted that if alkyl tertiary amine dihydrogen phosphate and β-hydroxyalanine are directly added without polymerization, ammonium chloride and alkyl tertiary amine dihydrogen phosphate will replace hydrogen phosphate in advance, and the hydrogen phosphate will then react with calcium ions to form phosphate precipitation. The slurry is very likely to undergo "instant coagulation" phenomenon, resulting in serious loss of workability of the grouting material. Therefore, the two are first reacted to be converted into a polymer, and the product needs to undergo hydrolysis, replacement and other steps to release hydrogen phosphate, so that the occurrence of this phenomenon is delayed. This is not only conducive to the interface growth strengthening component having enough time to penetrate into the microcracks, but also can make the distribution of hydrogen phosphate and β-hydroxyalanine more balanced, and play a more efficient role in promoting the transformation of metastable phosphate to stable hydroxyapatite.

[0037] As a preferred embodiment, the raw materials of the interface enhancer also include deionized water and potassium octadecenoate;

[0038] The powdered product is mixed with ammonium chloride and potassium octadecenoate to obtain the interface enhancer.

[0039] As a preferred embodiment, the raw materials of the modified admixture include the following components: green mud and ammonium dihydrogen phosphate, and the preparation of the modified admixture includes:

[0040] The chlorite is calcined to obtain a calcined product; in some embodiments, the calcination temperature is 900-1000°C.

[0041] adding the calcined product into water for reaction to obtain a colloidal mixture;

[0042] adding ammonium dihydrogen phosphate to the colloidal mixture to react and obtain a mixed product;

[0043] The mixed product is ground to obtain hydroxyapatite powder. In some embodiments, the mixed product is moved into a ball mill and ground for 10 to 20 minutes, taken out and filtered, and then ground to a particle size of less than 65 μm to obtain hydroxyapatite powder;

[0044] In the technical scheme, the main component of green mud is calcium carbonate, so the main component of the calcined product is calcium oxide. After the calcined product is added to water for reaction, the main component of the obtained colloidal mixture is calcium hydroxide colloid. When ammonium dihydrogen phosphate is added, ammonium dihydrogen phosphate reacts with calcium ions to form calcium dihydrogen phosphate precipitation. Therefore, the main components of the mixed product are calcium dihydrogen phosphate and calcium hydroxide. When the mixed product is ground, the calcium dihydrogen phosphate and calcium hydroxide react to form hydroxyapatite ( ), the reaction formula is as follows:

[0045] ;

[0046] In the present invention, when the interface enhancer plays a role, hydroxyapatite can provide crystal nucleus sites when metastable calcium hydrogen phosphate is converted into stable hydroxyapatite crystals, thereby promoting the conversion process.

[0047] As a preferred embodiment, the raw materials of the modified admixture further include deionized water, N,N-dimethylformamide and polyoxypropylene glycerol polyether.

[0048] N,N-dimethylformamide and polyoxypropylene glycerol polyether are sprayed on the surface of the hydroxyapatite micropowder, and the modified admixture is obtained after drying. In some embodiments, a drum dryer is used for drying at 45-60°C.

[0049] In the technical solution, N,N-dimethylformamide and polyoxypropylene glycerol polyether are mixed and then sprayed on the surface of the mixed product powder, which can improve the dispersibility of the two in the grouting material and facilitate better performance.

[0050] As a preferred embodiment, the grouting material is prepared by mixing the cementitious material, the interface enhancer and the modified admixture before use to form a mixed dry material, which is packaged independently and then mixed with water in proportion to prepare the grouting material during on-site construction, which helps to reduce transportation and storage costs.

[0051] One or more technical solutions provided by the present invention have at least the following technical effects or advantages:

[0052] 1. The interface enhancer of the present invention modifies the grouting material. When cement particles are blocked by microcracks, the interface enhancement component can further penetrate into the microcracks, thereby improving the diffusion performance of the grouting material and solving the problem of poor diffusion of suspension-type grouting materials such as cement in microcracked rock mass in the prior art.

[0053] 2. The interface enhancer generates stable hydroxyapatite crystals through a series of chemical reactions, which improves the filling degree between the grouting material and the rock mass, and improves the interface bonding performance between the grouting material and the rock mass.

[0054] 3. In the modified admixture of the present invention, the hydroxyapatite microspheres can provide nucleus sites for the growth of hydroxyapatite crystals in the interface enhancer, which is conducive to the better function of the interface enhancer; at the same time, the microsphere morphology can make the N,N-dimethylformamide and polyoxypropylene glycerol polyether attached to its surface more evenly dispersed in the slurry, further improving the diffusion performance of the grouting material.

[0055] 4. The present invention uses industrial waste green mud as part of the raw material to prepare hydroxyapatite, providing a new way to treat industrial waste and having the advantage of being environmentally friendly.

[0056] 5. The present invention adopts ultrafine silicate cement and bismuthinite powder as cementitious materials, wherein the ultrafine silicate cement particles have a small particle size, which ensures the diffusion performance of the grouting material; the molecular bonds on the cleavage plane of bismuthinite are weak and easy to break and dissociate; the bismuthinite powder formed under the grinding action is hydrophobic, which improves the anti-seepage performance of the cementitious material. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of the present invention, and do not constitute a limitation on the embodiments of the present invention;

[0058] Figure 1 The SEM images of the stone bodies of the grouting materials in Comparative Example 1 and Example 4 of the present invention are shown in the figure: (a) Comparative Example 1; (b) Example 4;

[0059] Figure 2 is the XRD spectrum of the grouting material in Example 4 of the present invention after curing for 28 days;

[0060] Figure 3 1 is a graph showing the strength development and shrinkage rate of the grouting material at different ages in Example 4 of the present invention, wherein: (a) compressive strength; (b) shrinkage rate. DETAILED DESCRIPTION

[0061] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0062] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those within the scope of this description. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0063] All raw materials of the present invention have no particular limitation on their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0064] There is no particular restriction on the purity of all raw materials in the present invention. The present invention preferably adopts analytically pure materials or materials with purity requirements conventional in the field of grouting material production.

[0065] All raw materials of the present invention, their brands and abbreviations are conventional brands and abbreviations in the field, and each brand and abbreviation is clear and definite in the field of its related use. Those skilled in the art can purchase them from commercially available products or prepare them by conventional methods according to the brands, abbreviations and corresponding uses.

[0066] Example 1

[0067] The present embodiment provides a grouting material, and its raw materials include the following components in parts by weight: 80 parts of cementitious material, 4.8 parts of interface enhancer, 1.7 parts of modified admixture and 60 parts of deionized water.

[0068] Wherein, the cementitious material is P·O 42.5 ultrafine silicate cement;

[0069] The raw materials of the interface enhancer include the following components by weight: 180 parts of deionized water, 80 parts of alkyl tertiary amine dihydrogen phosphate, 1.5 parts of β-hydroxyalanine, 3 parts of 4-cyanovaleric acid, 200 parts of tetrahydrofuran and 60 parts of ammonium chloride.

[0070] The preparation of the interface enhancer comprises the following steps:

[0071] S1.1: Deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine and 4-cyanovaleric acid were transferred into a hydrothermal reactor, and the temperature was slowly raised to 54°C for 100 min to obtain a hydrothermal reaction mother liquor;

[0072] S1.2: pouring the hydrothermal reaction mother liquor into tetrahydrofuran for precipitation, filtering after 12 min to obtain an intermediate precipitate product;

[0073] S1.3: placing the intermediate precipitate product in a forced air drying oven, drying at 50° C. for 130 min, and then crushing and grinding the product to obtain a powdery product;

[0074] S1.4: Mix the powdered product with ammonium chloride to obtain the interface enhancer.

[0075] The modified admixture is used to improve the fluidity of the grouting material. This embodiment uses a common polycarboxylate water reducer.

[0076] Example 2

[0077] On the basis of the above-mentioned embodiment 1, the components of the cementitious material further include bismuthinite powder, wherein the weight ratio of P·O 42.5 ultrafine silicate cement to bismuthinite powder is 90:10.

[0078] The raw materials of the interface enhancer also include deionized water and potassium octadecenoate, wherein the weight ratio of deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran, ammonium chloride and potassium octadecenoate is 200:100:1.7:4.1:200:72:0.5.

[0079] The preparation steps of the interface enhancer include S1.1 to S1.3 in Example 1, and further include the following steps:

[0080] S1.4: The powdered product is mixed with ammonium chloride and potassium octadecenoate to obtain the interface enhancer.

[0081] Example 3

[0082] On the basis of the above-mentioned Example 2, the raw materials of the modified admixture include the following components in parts by weight: 425 parts of deionized water, 97 parts of green mud, 72 parts of diammonium phosphate, 66 parts of N,N-dimethylformamide and 20 parts of polyoxypropylene glycerol polyether.

[0083] The preparation of the modified admixture comprises the following steps:

[0084] The green mud was calcined at 1000°C for 120 min to obtain a calcined product;

[0085] adding the calcined product into deionized water for reaction to obtain a colloidal mixture;

[0086] adding ammonium dihydrogen phosphate to the colloidal mixture to react and obtain a mixed product;

[0087] The mixed product was transferred into a ball mill and ground for 15 min, taken out and filtered, and ground to a particle size of less than 65 μm to obtain hydroxyapatite micropowder.

[0088] N,N-dimethylformamide and polyoxypropylene glycerol polyether are sprayed on the surface of the hydroxyapatite micropowder, and the modified admixture is obtained after drying.

[0089] Example 4

[0090] Based on the above Example 3, (1) preparing a gelling material:

[0091] The weight ratio of P·O 42.5 ultrafine silicate cement and bismuth ore powder is 90:10, and the cementitious material is obtained by uniformly mixing the ultrafine silicate cement and bismuth ore powder.

[0092] (2) Prepare an interface enhancer according to the method of Example 2:

[0093] Wherein, the weight ratio of deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran, ammonium chloride, and potassium octadecenoate is 180:80:1.5:3:200:60:0.4;

[0094] (3) Prepare the modified admixture according to the method of Example 3:

[0095] The weight ratio of deionized water, green mud, ammonium dihydrogen phosphate, N,N-dimethylformamide and polyoxypropylene glycerol polyether is 380:83:68:63:15;

[0096] (4) Preparation of grouting materials:

[0097] In terms of weight, 60 parts of deionized water, 80 parts of cementitious materials, 4.8 parts of interface enhancers, and 1.7 parts of modified admixtures are taken; water, cementitious materials, interface enhancers, and modified admixtures are poured into a stirring pot in sequence, and after being fully stirred, a highly diffusible micro-crack rock interface enhanced grouting material is obtained.

[0098] Example 5

[0099] Based on Example 4, the weight ratio of ultrafine silicate cement to bismuthinite powder is 85:15;

[0100] The weight ratio of deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran, ammonium chloride and potassium octadecenoate is 200:115:3:5:220:90:0.6;

[0101] The weight ratio of deionized water, green mud, ammonium dihydrogen phosphate, N,N-dimethylformamide and polyoxypropylene glycerol polyether is 500:110:76:70:25.

[0102] The weight ratio of deionized water, gelling material, interface enhancer and modified admixture is 120:120:6.5:2.2.

[0103] Comparative Example 1

[0104] Based on Example 4, no interface enhancer and modifying admixture are added.

[0105] Comparative Example 2

[0106] On the basis of Example 4, the interfacial enhancer was replaced by hydroxypropyl methylcellulose.

[0107] Comparative Example 3

[0108] Based on Example 4, the weight ratio of the cementitious material, the interface enhancer and the modified admixture is 140:3:5.

[0109] Comparative Example 4

[0110] On the basis of Example 4, in the raw materials of the interface enhancer, the weight ratio of deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran, ammonium chloride and potassium octadecenoate is 200:130:0.2:6:200:120:1.

[0111] Comparative Example 5

[0112] On the basis of Example 4, in the raw materials of the modified admixture, the weight ratio of deionized water, green mud, ammonium dihydrogen phosphate, N,N-dimethylformamide and polyoxypropylene glycerol polyether is 425:70:100:90:10.

[0113] Example 6

[0114] The grouting materials in Examples 1 to 5 and Comparative Examples 1 to 4 were tested for fluidity, water separation rate, setting time, and compressive strength. The test results are shown in Table 1.

[0115] Among them, fluidity, water separation rate, setting time and compressive strength are tested according to the methods in DLT 5823~2021 "Test Procedure for Cement-based Grouting Materials for Hydraulic Structures".

[0116] The diffusion performance was tested according to the following method:

[0117] (1) Cut the core specimen with a diameter of 50 mm and a height of 100 mm into two semi-cylindrical shapes along the diameter;

[0118] (2) Then join the two semi-cylindrical specimens together and leave a crack with a width of 20 to 100 μm;

[0119] (3) Use a pneumatic grouting pump to inject grout from one end of the specimen and collect the grout that passes through the cracks from the other end;

[0120] (4) Measure the mass of slurry passing through the cracks in the same period of time and use it as an evaluation indicator of diffusion performance.

[0121] The bond strength was tested according to the following method:

[0122] (1) Cut the core specimen with a diameter of 50 mm and a height of 100 mm into two semi-cylindrical shapes along the diameter;

[0123] (2) Then join the two semi-cylindrical specimens together and leave a crack with a width of 20 to 100 μm;

[0124] (3) After pouring the prepared grouting material slurry into the cracks, standard curing is performed for 28 days;

[0125] (4) Take out the specimen, make the busbar parallel to the horizontal plane, and perform a splitting tensile test. The splitting tensile strength is used as the evaluation index of the bonding performance.

[0126] Table 1

[0127]

[0128] The cementitious material of Example 1 is P·O 42.5 ultrafine silicate cement, the interface enhancer does not contain potassium octadecenoate, and the modified additive is a polycarboxylate water-reducing agent commonly used in the art; Example 2 is based on Example 1, bismuthinite powder is added to the cementitious material, and potassium octadecenoate is added to the interface enhancer. In comparison, the water separation rate of Example 2 is significantly reduced and the bonding strength is significantly enhanced. This is because the layered cleavage surface structure of the bismuthinite powder has natural hydrophobicity, which can improve the material's impermeability, and potassium octadecenoate can improve the dispersibility of the interface enhancer in the grouting material, which is more conducive to its function. Example 3 replaces the polycarboxylate water-reducing agent in Example 2 with the modified admixture of the present invention, and its diffusion performance and bonding strength are further improved, which reflects the synergistic effect of the interface enhancer and the modified admixture. Example 4 and Example 5 adjust the raw material ratio of each component of the grouting material on the basis of Example 3, but they are all within the scope defined by the present invention, and the various indicators are at the same level as Example 3; the ratios of Comparative Examples 3 to Comparative Examples 5 are outside the scope defined by the present invention, and the diffusion performance and bonding strength have decreased to varying degrees, indicating that the raw material ratio must be within the scope defined by the present invention to achieve the corresponding technical effect. Comparative Example 1 does not add interface enhancer and modified admixture, and its bonding strength is only 1.17MPa, and the diffusion performance is not good. Comparative Example 2, on the basis of Example 4, replaces the interface enhancer with hydroxypropyl methylcellulose, a common auxiliary agent in the field. Although the bonding strength is improved compared with Comparative Example 1, the fluidity loss is obvious and the diffusion performance is greatly reduced, indicating that the interface enhancer of the present invention has no negative impact on other properties while improving the diffusion performance and bonding strength of the grouting material.

[0129] Example 7

[0130] (1) The stone bodies of the grouting materials of Example 4 and Comparative Example 1 were observed using an electron microscope, and the following results were obtained: Figure 1 The SEM images shown are Figure 1 (a) It can be seen that the stone structure of the grouting material in Comparative Example 1 is loose and porous, indicating that there are many pores and channels inside the stone, resulting in poor mechanical properties and anti-permeability properties. Figure 1(b) shows that the stone structure of the material in Example 4 is more compact, indicating that the internal particles are closely arranged, the porosity and the number of channels are significantly reduced, and the bonding performance on the interface of micro-cracked rock mass is significantly enhanced;

[0131] (2) X-ray diffraction analysis was performed on the stone body of the grouting material in Example 4 after curing for 28 days, and the following results were obtained: Figure 2 From the XRD spectrum shown, we can see that the composition of the stone body mainly includes calcium hydroxide, calcite, calcium sulfonate, dicalcium silicate and tricalcium silicate. The presence of these components indicates that the grouting material forms stable hydration products during the solidification process, which has good mechanical properties and durability and is suitable for various complex engineering environments.

[0132] (3) The strength development and shrinkage rate of the grouting material in Example 4 were tested at different ages. The results are as follows: Figure 3 As shown by Figure 3 It can be seen that with the increase of age, the compressive strength of the grouting material continues to increase, and at 28 days, the compressive strength can reach about 35MPa. At the same time, the shrinkage rate also increases with the increase of age. At 56 days, the shrinkage rate is less than 0.20%, showing excellent mechanical properties and volume stability, which is suitable for the reinforcement of micro-cracked rock mass.

[0133] In summary, the grouting material of the present invention has a dense structure, excellent mechanical properties and anti-permeability properties, and forms a stable hydration product after solidification. It is suitable for various complex engineering environments, and is particularly suitable for reinforcing micro-cracked rock masses.

[0134] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0135] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A highly diffusible micro-crack rock interface enhanced grouting material, characterized in that: The raw materials of the grouting material include the following components: Cementitious materials, interface enhancers and modified admixtures; Wherein, the cementitious material comprises the following components: ultrafine silicate cement; The raw materials of the interface enhancer include the following components: deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran, ammonium chloride and potassium octadecenoate, wherein the weight ratio of deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine, 4-cyanovaleric acid, tetrahydrofuran, ammonium chloride and potassium octadecenoate is 180-200: 80-115: 0.5-3: 2.7-5.5: 190-220: 50-95: 0.36-0.68; The interface enhancer is prepared by the following steps: Deionized water, alkyl tertiary amine dihydrogen phosphate, β-hydroxyalanine and 4-cyanovaleric acid are transferred into a hydrothermal reaction kettle, and the temperature is raised to 50-57° C. to react, thereby obtaining a hydrothermal reaction mother liquor; pouring the hydrothermal reaction mother liquid into tetrahydrofuran for precipitation to obtain an intermediate precipitation product; Drying and grinding the intermediate precipitated product to obtain a powdery product; The powdered product is mixed with ammonium chloride and potassium octadecenoate to obtain the interface enhancer; The raw materials of the modified admixture include the following components: green mud and ammonium dihydrogen phosphate, and the weight ratio of green mud to ammonium dihydrogen phosphate is 83-110:68-76; The weight ratio of the gelling material, the interface enhancer and the modified admixture is 80-120:4.6-7.3:1.5-2.3; The modified admixture is prepared by the following steps: calcining the chlorite to obtain a calcined product; adding the calcined product into water for reaction to obtain a colloidal mixture; adding ammonium dihydrogen phosphate to the colloidal mixture to react and obtain a mixed product; The mixed product is ground to obtain hydroxyapatite fine powder.

2. The highly diffusible micro-crack rock interface enhanced grouting material according to claim 1, characterized in that: The components of the cementitious material also include bismuthinite powder, wherein the weight ratio of ultrafine silicate cement to bismuthinite powder is 82-95:5-18.

3. The highly diffusible micro-crack rock interface enhanced grouting material according to claim 1, characterized in that: The raw materials of the modified admixture also include deionized water, N,N-dimethylformamide and polyoxypropylene glycerol polyether, wherein the weight ratio of deionized water, green mud, ammonium dihydrogen phosphate, N,N-dimethylformamide and polyoxypropylene glycerol polyether is 350-500:83-110:68-76:63-70:15-25.

4. The method for preparing a highly diffusible microcrack rock interface enhanced grouting material according to any one of claims 1 to 3, characterized in that: The method comprises: preparing the gelling material; preparing the interface enhancer; preparing the modified admixture; The cementitious material, the interface enhancer and the modifying admixture are mixed with water to obtain the grouting material.

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