High thixotropy anchor rod grouting material, preparation method and application

Abstract

This invention discloses a high-thixotropic anchor grouting material, its preparation method, and its application. The grouting material comprises component A and component B; the mass ratio of component A to component B is 1:0.3-0.5. Component A comprises the following raw materials in parts by mass: 90-100 parts cement component, 0.3-1 part fiber component, 5-10 parts polyvinylpyrrolidone, and 0.5-2 parts dispersant stabilizer; the cement component includes low-alkali cement; the fiber component includes polyvinyl alcohol fiber; component B comprises the following raw materials in parts by mass: 3-8 parts trimethylolpropane tris(3-mercaptopropionate), 2-5 parts sorbitol polyglycidyl ether, and the balance being water. This invention utilizes a two-component (A+B) design. The cement component in component A provides a low-alkali environment, and the trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether in component B crosslink in this low-alkali environment to form a large number of network structures. The network structures contain a large number of hydroxyl groups, thereby improving the thixotropic properties of the grouting material.

Description

Technical Field

[0001] This invention relates to the field of civil engineering materials technology, specifically to a high thixotropic anchor grouting material, its preparation method, and its application. Background Technology

[0002] Anchor bolt grouting technology is an anchoring technique suitable for weak surrounding rock, fault fracture zones, sand and gravel, etc., where the borehole is prone to collapse after drilling. It combines anchor bolts with grouting. The anchor bolts provide support, while the grouting fills the cracks in the surrounding rock. Through the bonding effect of the grouting material, the surrounding rock with pores around the anchor bolts forms a whole, improving the surrounding rock's ability to withstand deformation.

[0003] Currently, the grouting material used in engineering is mainly ordinary cement paste. However, ordinary cement paste is prone to settling and bleeding, which makes it impossible to form a stable anchoring grouting layer. The anchor holes are prone to collapse. Moreover, cement paste has low thixotropy, and its viscosity recovers slowly after grouting (when stationary), making it easy to flow. This results in the grouting material failing to tightly bond with the surrounding rock and soil, leading to poor anchoring effect. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of low thixotropy of existing grouting materials and unstable anchoring grouting layers.

[0005] To achieve the above objectives, the present invention provides a high thixotropic anchor grouting material, comprising component A and component B; the mass ratio of component A to component B is 1:0.3-0.5; component A comprises the following raw materials in parts by mass: 90-100 parts cement component, 0.3-1 part fiber component, 5-10 parts polyvinylpyrrolidone (PVP), and 0.5-2 parts dispersant stabilizer; the cement component comprises low-alkali cement; the fiber component comprises polyvinyl alcohol fiber; component B comprises the following raw materials in parts by mass: 3-8 parts trimethylolpropane tris(3-mercaptopropionate), 2-5 parts sorbitol polyglycidyl ether, and the balance being water.

[0006] Optionally, the above-mentioned low-alkali cement can be any cement with a total alkali content (in Na2O equivalent) ≤0.6wt%, such as silicate cement, sulfoaluminate cement, aluminate cement, etc.

[0007] Optionally, the mass ratio of the above-mentioned low-alkali cement, trimethylolpropane tris(3-mercaptopropionate), and sorbitol polyglycidyl ether is (45-60):(3-8):(2-5).

[0008] Optionally, the above-mentioned cement components also include rapid-hardening cement, and the mass ratio of rapid-hardening cement to low-alkali cement is 1:1-2.

[0009] Optionally, the aforementioned rapid-hardening cement is a sulfoaluminate cement with a strength grade of 42.5.

[0010] Optionally, the average length of the polyvinyl alcohol fibers is 3mm-10mm.

[0011] Optionally, the length of the polyvinyl alcohol fiber includes: a first length and a second length; the first length is less than or equal to 5 mm, and the second length is greater than the first length.

[0012] Optionally, the above-mentioned polyvinylpyrrolidone is polyvinylpyrrolidone-K-60.

[0013] Optionally, the above-mentioned dispersing stabilizer includes polycarboxylate superplasticizer and hydroxypropyl methylcellulose ether, wherein the mass ratio of polycarboxylate superplasticizer to hydroxypropyl methylcellulose ether is (3-5):1.

[0014] The present invention also provides a method for preparing the above-mentioned high thixotropic anchor grouting material, comprising: 1) Preparation of Component A: The cement component, fiber component, polyvinylpyrrolidone, and dispersant stabilizer in the formula amount of Component A are mixed to obtain Component A; 2) Preparation of component B: The prescribed amounts of trimethylolpropane tris(3-mercaptopropionate), sorbitol polyglycidyl ether, and water in component B are mixed to obtain component B; The high thixotropic anchor grouting material is obtained by mixing the above components A and B.

[0015] The present invention also provides the application of the above-mentioned high thixotropic anchor grouting material, which can be used for anchor grouting. In application, component B is prepared and used immediately, and component A and component B are mixed together during application.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1) This invention employs a two-component (A+B) design. Component A, the cement component, provides a low-alkali environment. Under this environment, trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether in component B can crosslink to form a large number of network structures. These network structures contain numerous hydroxyl groups (-OH), and extensive intermolecular hydrogen bonds exist between these hydroxyl groups and between hydroxyl groups and water molecules. When the grouting material is pumped (under external force), the intermolecular hydrogen bonds in the grouting material break, the network structure partially disintegrates, and the viscosity of the grouting material decreases significantly. After grouting is completed (at rest), the intermolecular hydrogen bonds in the grouting material reconnect, the network structure re-entangles, and the viscosity of the grouting material rapidly increases, thus giving the grouting material of this invention excellent thixotropic properties.

[0017] 2) Component B of the present invention includes: water, trimethylolpropane tris(3-mercaptopropionate), and sorbitol polyglycidyl ether. Component B is prepared and used immediately, and components A and B are mixed together before application.

[0018] On the one hand, it can reduce the network structure formed in the early stage of grouting material and ensure the fluidity of grouting material during the early pumping process.

[0019] On the other hand, it allows the cross-linking reaction of component B (generating an organic network structure) and the hydration reaction of component A cement and component B water (generating an inorganic network structure) to occur simultaneously. The organic network structure and the inorganic network structure interpenetrate and grow to form an organic-inorganic interpenetrating network structure, thereby improving the overall strength of the grouting material after hardening.

[0020] 3) The cement component in component A of this invention uses low-alkali cement, placing component B in a cross-linking reaction environment with suitable alkalinity. If the alkalinity of the cement in component A is too high, the cross-linking reaction rate of component B will be too fast, resulting in an excessively rapid formation of the cross-linked network structure and reduced initial pumpability of the grouting material. Conversely, if the alkalinity of the cement in component A is too low, the cross-linking reaction rate of component B will be too slow, leading to slow viscosity recovery of the grouting material after grouting and increased flowability. Thus, components A and B synergistically improve the thixotropic properties of the grouting material of this invention. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the drilling arrangement for grouting in the surrounding rock according to the present invention.

[0022] Figure 2 This is an acoustic reflection waveform diagram of the grouting material after drilling and grouting in Embodiment 1 of the present invention.

[0023] Figure 3 This is an acoustic reflection waveform diagram of the grouting material after drilling and grouting in Embodiment 2 of the present invention.

[0024] Figure 4 This is an acoustic reflection waveform diagram of the grouting material after drilling and grouting in Embodiment 3 of the present invention.

[0025] Figure 5 This is an acoustic reflection waveform diagram of the grouting material after drilling and grouting in Embodiment 4 of the present invention.

[0026] Figure 6 This is an acoustic reflection waveform diagram of the grouting material used in Comparative Example 1 of the present invention after drilling and grouting.

[0027] Figure 7 This is an acoustic reflection waveform diagram of the grouting material used in Comparative Example 3 of the present invention after drilling and grouting.

[0028] Figure 8 This is an acoustic reflection waveform diagram of the grouting material used in Comparative Example 4 of the present invention after drilling and grouting. Detailed Implementation

[0029] Terminology Explanation Thixotropy: The thixotropy of grouting materials refers to the decrease in viscosity under external force (during pumping) and the recovery of viscosity after the external force is stopped (when at rest).

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] As described in the background section, the grouting material currently used in engineering is mainly ordinary cement paste. However, ordinary cement paste has low thixotropy, and its viscosity recovers slowly after grouting (when stationary), making it prone to flowing.

[0032] Currently, attempts to address this issue involve adding inorganic thickeners such as bentonite and silica fume to the grouting material to increase its viscosity at rest and improve its thixotropy. However, grouting materials produced in this way typically suffer from poor compressive strength.

[0033] This invention introduces a polyhydroxy (-OH) network structure into grouting materials for the first time. Utilizing the extensive intermolecular hydrogen bonds between hydroxyl groups and between hydroxyl groups and water molecules, and the reversible breaking of these hydrogen bonds, the network structure partially disintegrates when the grouting material is pumped (under external force), reducing the viscosity of the grouting material. After grouting is completed (at rest), the hydrogen bonds reconnect, the network structure re-entangles, and the viscosity of the grouting material rapidly increases, thereby improving the thixotropic properties of the grouting material of this invention. Simultaneously, the network structure introduced in this invention itself possesses high hardening strength, which can improve the compressive strength of the grouting material.

[0034] Specifically, the grouting material of the present invention includes component A and component B; the mass ratio of component A to component B is 1:0.3-0.5; wherein, the raw materials of component A include, by mass parts, 90-100 parts of cement component, 0.3-1 part of fiber component, 5-10 parts of polyvinylpyrrolidone, and 0.5-2 parts of dispersant stabilizer; the cement component includes low-alkali cement; the fiber component includes polyvinyl alcohol fiber; the raw materials of component B include, by mass parts, 3-8 parts of trimethylolpropane tris(3-mercaptopropionate), 2-5 parts of sorbitol polyglycidyl ether, and the balance being water.

[0035] This invention employs a two-component (A+B) design. The cement component in component A provides a low-alkali environment. Under this environment, trimethylolpropane tris(3-mercaptopropionate) in component B can crosslink with sorbitol polyglycidyl ether to form a large number of network structures. The following example illustrates the reaction between sorbitol polyglycidyl ether carrying a monoepoxy group and trimethylolpropane tris(3-mercaptopropionate), with the following reaction formula:

[0036] The thiolate anion in trimethylolpropane tris(3-mercaptopropionate) undergoes nucleophilic ring-opening attack on the epoxy groups in sorbitol polyglycidyl ether under alkaline conditions, forming thioether bonds and subsequently a spatial network structure. The above reaction formula uses sorbitol polyglycidyl ether carrying a single epoxy group as an example. In reality, the number of epoxy groups in sorbitol polyglycidyl ether is random, and can be any one or more of 1 to 6. As the number of epoxy groups in sorbitol polyglycidyl ether increases, the degree of crosslinking between trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether strengthens.

[0037] The aforementioned network structure contains a large number of hydroxyl groups (-OH), and these hydroxyl groups are extensively bonded to each other, as well as to water molecules. When the grouting material is pumped (under external force), the intermolecular hydrogen bonds break, the network structure partially disintegrates, and the viscosity of the grouting material is significantly reduced. After grouting is completed (at rest), the intermolecular hydrogen bonds of the grouting material reconnect, the network structure re-entangles, the viscosity of the grouting material rapidly increases, and the thixotropic properties are greatly enhanced.

[0038] Furthermore, component B of this invention is prepared and used immediately. Components A and B are then mixed during application. This serves two purposes: first, it reduces the network structure formed in the early stages of the grouting material, ensuring its pumpability in the early stages; second, it allows the cross-linking reaction of component B (generating an organic network structure) and the hydration reaction between cement component A and water component B (generating an inorganic network structure) to occur simultaneously. This allows the organic and inorganic network structures to interpenetrate and grow, forming an organic-inorganic interpenetrating network structure, thereby improving the overall strength of the grouting material after hardening.

[0039] In some embodiments, the low-alkali cement is cement with a total alkali content of ≤0.6wt%, and the mass ratio between the low-alkali cement, trimethylolpropane tris(3-mercaptopropionate), and sorbitol polyglycidyl ether is (45-60):(3-8):(2-5).

[0040] In some embodiments, the cement component in component A also includes rapid-hardening cement, which enables the grouting material to quickly achieve a certain hardness after grouting, thus shortening the construction period. Specifically, the rapid-hardening cement can be sulfoaluminate cement with a strength grade of 42.5, and the mass ratio of rapid-hardening cement to low-alkali cement is 1:1-2.

[0041] In some embodiments, the average length of the polyvinyl alcohol (PVA) fibers in component A is 3 mm to 10 mm. PVA fibers have high strength, high modulus, and low elongation, which can improve the strength of the grouting material. Specifically, the length of the PVA fibers includes a first length and a second length; the first length is less than the second length, and the first length is less than or equal to 5 mm. The mixture of long and short fibers optimizes the spatial distribution of the fibers; short fibers can fill the gaps between long fibers, forming a dense fiber network and improving the overall strength of the grouting material.

[0042] In some embodiments, the polyvinyl alcohol fiber can be a mixture of 3mm and 6mm polyvinyl alcohol fibers, with a mass ratio of 1-2:1 for 3mm and 6mm polyvinyl alcohol fibers.

[0043] In some embodiments, the polyvinylpyrrolidone in component A can crosslink into an adhesive under alkaline and exothermic conditions during cement hydration, thereby improving the anchoring properties of the grouting material.

[0044] In some embodiments, the dispersant stabilizer in component A includes polycarboxylate superplasticizer and hydroxypropyl methylcellulose ether, with a mass ratio of polycarboxylate superplasticizer to hydroxypropyl methylcellulose ether of (3-5):1.

[0045] The present invention will be further described below with reference to specific embodiments.

[0046] The rapid-hardening cement used in this embodiment is sulfoaluminate cement R·SAC 42.5 grade, and the low-alkali cement is silicate cement (low-alkali), both purchased from Beijing Jinyu Group Co., Ltd.; trimethylolpropane tris(3-mercaptopropionate) and polyvinylpyrrolidone-K-60 were both purchased from Sigma-Aldrich; polyvinyl alcohol fiber was purchased from Shanghai Shenxiang Concrete Fiber Co., Ltd., polycarboxylate superplasticizer was purchased from Jiangsu Subote New Material Co., Ltd., hydroxypropyl methylcellulose was purchased from Jiangsu Zhaojia Building Materials Technology Co., Ltd., and sorbitol polyglycidyl ether was purchased from Shaoguan Yang'an Chemical Co., Ltd.

[0047] Example 1 This embodiment provides a high thixotropic tunnel grouting material, which is formed by mixing component A and component B on site at a mass ratio of 1:0.4.

[0048] The raw materials for component A include, by mass, 50 parts of silicate cement (low alkali), 50 parts of sulfoaluminate cement R·SAC42.5 grade, 0.6 parts of polyvinyl alcohol fiber, 8 parts of polyvinylpyrrolidone-K-60, and 1.5 parts of dispersant stabilizer (polycarboxylate superplasticizer and hydroxypropyl methylcellulose in a mass ratio of 3:1). The polyvinyl alcohol fiber includes 3mm polyvinyl alcohol fiber and 6mm polyvinyl alcohol fiber, with a mass ratio of 1:1.

[0049] Add the above components to a high-efficiency mixer according to the formula amount, mix for 15-30 minutes until the color is uniform, and you will get component A.

[0050] The raw materials of component B include, by mass, 4.8 parts of trimethylolpropane tris(3-mercaptopropionate), 3.6 parts of sorbitol polyglycidyl ether, and the balance being water.

[0051] Add the above components to a high-efficiency mixer according to the formula amount and mix for 15-30 minutes to obtain component B.

[0052] Component A is pre-prepared and packaged, while component B needs to be prepared on-site. The dry powder of component A and the emulsion of component B are added to a high-speed mixer to form a uniform, viscous grouting material. This grouting material shows no bleeding or flowing when left to stand, and the pumping process is smooth. After grouting, the grout immediately returns to a highly viscous state without backflow.

[0053] Example 2 The difference between this embodiment and Example 1 is that, in component A, polyvinyl alcohol fiber is 1 part, polyvinylpyrrolidone is 10 parts, and dispersant stabilizer is 2 parts. In component B, trimethylolpropane tris(3-mercaptopropionate) is 6 parts, and sorbitol polyglycidyl ether is 4 parts.

[0054] Example 3 The difference between this embodiment and Example 1 is that, in component A, polyvinyl alcohol fiber is 0.3 parts, polyvinylpyrrolidone is 5 parts, and dispersant stabilizer is 0.5 parts. In component B, trimethylolpropane tris(3-mercaptopropionate) is 4 parts, and sorbitol polyglycidyl ether is 3.2 parts.

[0055] Example 4 The difference between this embodiment and Example 1 is that the mass ratio of component A to component B is 1:0.3, and in component B, trimethylolpropane tris(3-mercaptopropionate) is 3.6 parts and sorbitol polyglycidyl ether is 2.7 parts.

[0056] Comparative Example 1 The difference between this comparative example and Example 1 is that trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether were not added.

[0057] Comparative Example 2 The difference between this comparative example and Example 1 is that trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether were replaced with 1,2-epoxypropane and 2-mercaptoethanol, all of which were purchased from Sigma-Aldrich.

[0058] Comparative Example 3 The difference between this comparative example and Example 1 is that trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether are replaced with nano-Fe3O4 (particle size 100-200nm).

[0059] Comparative Example 4 The difference between this comparative example and Example 1 is that trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether were replaced with bentonite, which was purchased from Hexinrunda Bentonite Mining Co., Ltd.

[0060] The performance of the grouting materials prepared in the various embodiments and comparative examples was tested according to the methods in the following standards: The fluidity and bleeding rate were tested according to TB / T 3192-2008, the compressive strength was tested according to GB / T 17671-1999, and the bond strength and anchoring force were tested according to JGJ / T 401-2017. The performance test results of the grouting materials prepared in each embodiment and comparative example are shown in Table 1 below.

[0061] Table 1. Performance of grouting materials prepared in each embodiment and comparative example.

[0062] As shown in Table 1, the present invention has the following advantages: (1) Excellent thixotropy and workability: Examples 1-4 of the present invention have moderate initial flow time, small increase in flow time after 30 min, and extremely low bleeding rate (≤0.3%), indicating good thixotropy of the slurry, which is easy to pump and can prevent flow when stationary. Comparative Example 1 did not add trimethylolpropane tris(3-mercaptopropionate) and sorbitol polyglycidyl ether, resulting in poor flowability and flow retention, and severe bleeding; Comparative Example 2 replaced the flow with single-chain material, which had a certain improvement effect compared with Comparative Example 1, but failed to form a spatial network structure, and still had a large gap compared with Examples 1-4. Comparative Examples 3 and 4 used conventional thixotropic materials, and the improvement effect on flowability and flow retention was generally average.

[0063] (2) Ultra-high mechanical properties and bond strength: The 28-day compressive strength of Examples 1-4 of the present invention is >54MPa, the bond strength is >12.5MPa, and the anchoring force is >175kN, demonstrating excellent overall performance. The mechanical properties of Comparative Example 1 are significantly reduced, proving that the organic-inorganic interpenetrating network of the present invention is the core that provides ultra-high strength. The performance of Comparative Example 2 is significantly reduced, indicating that the specific thiol-epoxy system is irreplaceable.

[0064] Furthermore, the field application of the grouting materials in each embodiment and comparative example was simulated: drilling was carried out before the grouting reinforcement operation, with the boreholes arranged on the top of the surrounding rock and drilled along a direction perpendicular to the inner wall of the surrounding rock, such as... Figure 1As shown, the borehole diameter is 10.0 cm and the borehole depth is 5.0 m. After the drilling operation is completed, the coal dust and rock cuttings in the borehole are removed.

[0065] Grouting was performed on the boreholes, and the anchorage density at the 60° position of the boreholes in each embodiment and comparative example ① was tested using the acoustic reflection method. Figures 2-8 As shown in the figure, compared to comparative examples 1-4, the waveforms of embodiments 1-4 of the present invention are more regular and exhibit faster decay, 2L / C. m Before the specified time, there were no defects or only weak defect reflection waves, and the bottom reflection wave signal was absent or not very obvious. This indicates that the grouting material of Examples 1-4 of the present invention exhibits no segregation and no shrinkage, and the grouting is full and dense, which is superior to Comparative Examples 1-4.

[0066] In summary, this invention discloses a high-thixotropic anchor grouting material, its preparation method, and its application. The grouting material comprises component A and component B; the mass ratio of component A to component B is 1:0.3-0.5. Component A comprises the following raw materials in parts by mass: 90-100 parts cement, 0.3-1 part fiber, 5-10 parts polyvinylpyrrolidone, and 0.5-2 parts dispersant stabilizer. Component B comprises the following raw materials in parts by mass: 3-8 parts trimethylolpropane tris(3-mercaptopropionate), 2-5 parts sorbitol polyglycidyl ether, with the balance being water. The anchor grouting material of this invention exhibits excellent thixotropy, bonding strength, and good toughness, which is of great significance for ensuring the quality and safety of grouting projects.

[0067] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A high-thixotropic anchor grouting material, characterized in that, It includes component A and component B; the mass ratio of component A to component B is 1:0.3-0.5; Component A comprises the following raw materials in parts by weight: The composition comprises 90-100 parts cement, 0.3-1 part fiber, 5-10 parts polyvinylpyrrolidone, and 0.5-2 parts dispersant stabilizer; the cement component includes low-alkali cement; the fiber component includes polyvinyl alcohol fiber. Component B comprises the following raw materials in parts by weight: 3-8 parts of trimethylolpropane tris(3-mercaptopropionate), 2-5 parts of sorbitol polyglycidyl ether, and the balance being water.

2. The high thixotropic anchor grouting material as described in claim 1, characterized in that, The low-alkali cement is cement with a total alkali content of ≤0.6wt%, and the mass ratio of the low-alkali cement, trimethylolpropane tris(3-mercaptopropionate), and sorbitol polyglycidyl ether is (45-60):(3-8):(2-5).

3. The high thixotropic anchor grouting material as described in claim 1, characterized in that, The cement components also include rapid-hardening cement, and the mass ratio of the rapid-hardening cement to the low-alkali cement is 1:1-2; the rapid-hardening cement is sulfoaluminate cement with a strength grade of 42.

5.

4. The high thixotropic anchor grouting material as described in claim 1, characterized in that, The average length of the polyvinyl alcohol fiber is 3mm-10mm.

5. The high thixotropic anchor grouting material as described in claim 4, characterized in that, The length of the polyvinyl alcohol fiber includes: a first length and a second length; the first length is less than or equal to 5 mm, and the second length is greater than the first length.

6. The high thixotropic anchor grouting material as described in claim 1, characterized in that, The polyvinylpyrrolidone is polyvinylpyrrolidone-K-60.

7. The high thixotropic anchor grouting material as described in claim 1, characterized in that, The dispersion stabilizer includes a polycarboxylate superplasticizer and a hydroxypropyl methylcellulose ether, wherein the mass ratio of the polycarboxylate superplasticizer to the hydroxypropyl methylcellulose ether is (3-5):

1.

8. A method for preparing a high-thixotropic anchor grouting material as described in any one of claims 1-7, characterized in that, include: 1) Preparation of Component A: The cement component, fiber component, polyvinylpyrrolidone, and dispersant stabilizer in the formula amount of Component A are mixed to obtain Component A; 2) Preparation of component B: The prescribed amounts of trimethylolpropane tris(3-mercaptopropionate), sorbitol polyglycidyl ether, and water in component B are mixed to obtain component B; The high thixotropic anchor grouting material is obtained by mixing the components A and B.

9. An application of the high thixotropic anchor grouting material as described in any one of claims 1-7, characterized in that, Used for anchor bolt grouting.

10. The application of the high thixotropic anchor grouting material as described in claim 9, characterized in that, Component A and component B are mixed during application.

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