Water-resistant rebound-inhibiting tackifier, method of making and using, and applications

Abstract

The application belongs to the technical field of civil engineering materials, and discloses a water-resistant rebound inhibiting viscosity increasing agent, a preparation and use method and application. The water-resistant rebound inhibiting viscosity increasing agent comprises the following components in parts by weight: a water-resistant component 2-11.5 parts, a water-retention thickening component 3-32.5 parts, a fiber viscosity increasing component 5-10 parts, a rheological synergistic component 25-50 parts, an early strength component 20-40 parts, and a nano-enhancing additive 1-5.5 parts. The application can effectively improve the cohesion and water erosion resistance of sprayed concrete and a humid rock surface, improve the cohesion of the sprayed concrete itself, improve the early strength of the sprayed concrete, and thus greatly reduce the rebound rate of the sprayed concrete, improve the construction quality, and effectively reduce the comprehensive cost of the sprayed concrete.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering materials technology, and more specifically relates to a water-resistant rebound inhibitor, preparation and use method and application, especially its application in shotcrete for water-rich tunnels. Background Technology

[0002] Shotcrete is an important component of tunnel support structures. It is a type of concrete produced by spraying a concrete mixture onto a target surface using specialized machinery and compressed air or other power, allowing it to solidify and harden. Shotcrete is widely used in tunnels, coal mine shafts, slope protection, and maintenance projects due to its fast construction speed, simple process, and flexible operation. Composite lining structures, composed of shotcrete, anchor bolts, and cast-in-place secondary lining concrete, are also a mainstream technical solution for railway tunnel support in my country. In composite lining structures, shotcrete plays a crucial role in forming the support structure, controlling rock relaxation and deformation, and preventing rock degradation.

[0003] The main performance characteristics of shotcrete are rapid setting time, rapid early strength gain, self-compacting effect, and synergistic deformation capability. Under the dynamic action of compressed air jet, it can form good adhesion with tunnel rock walls or slopes and quickly solidify on the rock surface. However, in actual engineering applications, the adhesion between shotcrete and rock walls does not form and function as quickly as designed. This manifests as a large amount of shotcrete sprayed onto the rock or slope surface bouncing back and falling off, i.e., a high rebound rate. Generally, the rebound rate of shotcrete in tunnel engineering is around 20% to 30%, and in some cases it can reach 50%. Especially under the conditions of damp rock surfaces in water-rich or water-rushing tunnels, shotcrete, due to its generally poor water resistance, is significantly weakened by the isolation effect of the water film on the rock wall and the scouring effect of the flowing water after contact with the damp rock surface, resulting in an even higher rebound rate. Currently, many methods have been proposed by technicians to reduce the rebound rate of shotcrete, mainly considering both process equipment and materials themselves. On the one hand, this involves optimizing and improving shotcrete construction processes and equipment, adopting wet spraying instead of traditional dry spraying, developing new types of spraying machines, and optimizing process parameters such as spraying pressure and angle. On the other hand, it involves optimizing and improving the shotcrete materials themselves, such as optimizing mix proportions, increasing cement strength, and incorporating high-performance accelerators, high-efficiency water-reducing agents, fibers, and thickeners to improve shotcrete performance. The effects of these various improvement methods vary, and no single, effective, and unified measure has yet been established. The optimization and improvement of shotcrete performance is an ongoing process.

[0004] Current concrete additives have several problems: Patent CN202010979238.9 mainly improves the performance of shotcrete through thickening and early strength enhancement, and improves its mechanical and durability properties, but does not address the needs of wet interfaces. Patent CN202010891868.0 mainly consists of materials with water-reducing and defoaming functions, aiming to accelerate the early strength growth of shotcrete, but does not have thickening or water-resistant functions. Patent CN202011346897.5 is mainly an invention based on conventional mineral admixtures such as fly ash, silica fume, metakaolin, and gypsum, primarily aimed at improving the density and durability of shotcrete. Patent CN202110946845.X mainly uses composites of different types of fibers to improve the cohesiveness of shotcrete, but does not improve the performance of shotcrete at wet interfaces. Patent CN202210750922.9 mainly improves the performance of shotcrete through accelerators and nano-suspending agents. Patent CN201910371601.6 primarily focuses on the self-adhesive and early-strength properties of shotcrete, but it does not improve the adhesion of shotcrete to wet interfaces. Patent CN201711294401.2 mainly uses water-reducing agents, defoamers, thickeners, and mineral admixtures, aiming to improve the corrosion resistance of shotcrete, but it also does not improve the adhesion performance of shotcrete in water-rich or water-rushing tunnels. In summary, there are currently no effective solutions to address the poor adhesion, poor water resistance, and high rebound rate of shotcrete at wet interfaces in water-rich tunnels.

[0005] Therefore, how to provide a water-resistant rebound inhibitor and thickener for shotcrete in water-rich tunnels is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] To overcome the shortcomings and deficiencies of the existing technology, this invention provides a water-resistant rebound inhibitor, its preparation and use method, and its application. It mainly improves the cohesiveness and water erosion and scouring resistance of the shotcrete mixture through physical and chemical actions, enhances its adhesion to damp rock walls in flowing water, and ensures that it can quickly bond, solidify and solidify on damp rock walls in water-filled tunnels, thereby significantly reducing the rebound rate.

[0007] One objective of this invention is to provide a water-resistant rebound inhibitory tackifier, specifically comprising:

[0008] Water-resistant component 2-11.5 parts, water-retaining and thickening component 3-32.5 parts, fiber thickening component 5-10 parts, rheology enhancing component 25-50 parts, early strength component 20-40 parts, nano-reinforcing agent 1-5.5 parts.

[0009] Preferably, the water-resistant component is selected from one or a combination of two of ethylene-vinyl acetate powder, fluoropolyacrylate powder, and chloroprene-ethylene-vinyl laurate powder.

[0010] The beneficial effects of the above technical solution are as follows: Fluorinated polyacrylate powder and chloroprene-ethylene-vinyl laurate powder can react with calcium hydroxide, a cement hydration product, causing the ester bond to decompose. The powder will then connect with the cement-based material through electrostatic adsorption, making it less likely to fall off in a water environment. In addition, the fluorinated polyacrylate powder and chloroprene-ethylene-vinyl laurate powder in the water-resistant components have a low "hydrophilic-lipophilic balance value", and the film formed has excellent water resistance sensitivity, making it suitable for water-rich tunnel environments.

[0011] Preferably, the water-retaining and thickening component is selected from one or a combination of two of polyacrylamide, polyethylene oxide, hydroxypropyl methylcellulose, and bentonite; the weight-average molecular weight of the polyacrylamide is 4 million to 12 million; the weight-average molecular weight of the polyethylene oxide is 800,000 to 5 million; and the weight-average molecular weight of the hydroxypropyl methylcellulose is 50 million to 100,000.

[0012] The beneficial effects of the above technical solution are: by selecting water-retaining and thickening components with reasonable weight-average molecular weight, not only can the water resistance of concrete with added water-retaining and thickening components be significantly improved, but also the viscosity of the concrete can be kept low and the workability can meet the application requirements.

[0013] Preferably, the fiber adhesive component is selected from one or a combination of two of chopped polyvinyl alcohol fibers, lignin fibers, polypropylene fibers, and polyacrylonitrile fibers; the length of the chopped polyvinyl alcohol fibers, polypropylene fibers, and polyacrylonitrile fibers is 2mm-5mm; and the length of the lignin fibers is 1mm-2mm.

[0014] Preferably, the rheology enhancing component is selected from one or a combination of two of fly ash, microspheres, mineral powder, silica fume, and ultrafine stone powder; the fly ash is Class I fly ash; the content of particles with a diameter of less than 10 μm in the microspheres is ≥90%; and the specific surface area of ​​the mineral powder is ≥500 m². 2 / kg; the silica content of the silica fume is ≥90%; the specific surface area of ​​the ultrafine stone powder is ≥600m². 2 / kg.

[0015] The beneficial effects of the above technical solution are: the rheology enhancement component has a certain microsphere structure and very low reactivity during the mixing stage, which can significantly improve the rheological properties of fresh concrete.

[0016] Preferably, the early-strength component is selected from one or a combination of two of sulfoaluminate cement, C3S micro powder, and ultrafine ordinary Portland cement; the C3S micro powder is industrial grade; and the ultrafine ordinary Portland cement has a specific surface area of ​​600 m². 2 / kg~900m 2 / kg.

[0017] The beneficial effects of the above technical solutions are: sulfoaluminate cement and ultrafine ordinary silicate cement react rapidly with water and release heat, which can enable concrete to have a certain strength in a short time; C3S micro powder has a lower reaction activity than the above two materials, but when C3S micro powder is used in combination with the above two materials, it can also have a certain strength in a short time due to thermal activation. In addition, C3S micro powder has a higher strength growth rate in the later stage of the reaction, which can increase the later strength of concrete accordingly.

[0018] Preferably, the nano-reinforcing agent is selected from one of nano-CSH gel, nano-SiO2, and nano-calcium carbonate.

[0019] The beneficial effects of the above technical solution are: through the nano-effect, the nano-reinforcing additive can organically integrate the concrete raw materials into a whole by adding only a small amount to the concrete, thereby significantly improving the tensile strength and flexural strength of the concrete and effectively reducing the rebound rate of shotcrete in water-rich tunnel environments.

[0020] A second objective of this invention is to provide a method for preparing a water-resistant rebound inhibitory tackifier, comprising the following steps:

[0021] (1) Weigh each component according to the stated weight proportions;

[0022] (2) Add the rheology enhancement component, fiber thickening component, water-retaining and thickening component and nano-reinforcing agent into a biaxial high-speed disperser and disperse at 1000-1400 r / min for 5 min to obtain a mixture;

[0023] (3) Add the mixture obtained in step (2) into a gravity mixer, and add water-resistant components and early strength components at the same time. Mix them together at 20-40 r / min for 10 min to obtain a water-resistant rebound inhibitor thickener.

[0024] The third objective of this invention is to provide an application of a water-resistant rebound inhibitory thickener in the production of shotcrete for water-rich tunnels.

[0025] The fourth objective of this invention is to provide a method for using a water-resistant rebound inhibitor and thickener, wherein the water-resistant rebound inhibitor and thickener is added together with cement during the production of shotcrete, and the amount added per cubic meter of concrete is 10kg to 30kg, replacing cement by the same mass.

[0026] As can be seen from the above technical solution, compared with the prior art, the present invention has at least the following beneficial effects:

[0027] This invention addresses the problems of poor adhesion, easy detachment, and high rebound rate of shotcrete in water-rich or water-bearing tunnels under flowing water or damp conditions. It proposes a water-resistant rebound-inhibiting thickener that organically combines water-resistant components, water-retaining thickening components, fiber-based thickening components, and rheology-enhancing components. Without reducing the fluidity of the shotcrete or prolonging the setting time, it effectively improves the cohesiveness and water erosion resistance of the shotcrete to damp rock surfaces, while also enhancing the shotcrete's own cohesiveness. The addition of early-strength components and nano-reinforcing additives improves the early strength and integrity of the shotcrete, thereby significantly reducing the rebound rate, improving construction quality, and effectively reducing the overall cost of shotcrete. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a water-resistant rebound-inhibiting tackifier. The components are accurately weighed according to the following weight proportions: 30 parts rheology modifier (20 parts microspheres, 10 parts silica fume), 5 parts fiber tackifier (3 parts lignin fiber, 2 parts polypropylene fiber), 25 parts water-retaining thickener (3 parts polyacrylamide, 22 parts bentonite), and 1.5 parts nano-reinforcing agent (1.5 parts nano CSH gel). These components are then added to a biaxial high-speed disperser and dispersed at 1000–1400 r / min for 5 min. The mixture is then placed in a gravity mixer, and simultaneously weighed according to the following weight proportions: 11.5 parts water-resistant component (5.5 parts ethylene-vinyl acetate powder, 6 parts fluoropolyacrylate powder) and 27 parts early-strength component (24 parts low-alkali sulfoaluminate cement, 3 parts C3S micro powder). These components are then added to the gravity mixer and mixed together at 20–40 r / min for 10 min to obtain the water-resistant rebound-inhibiting tackifier.

[0031] Example 2

[0032] This embodiment provides a water-resistant rebound-inhibiting thickener. The components are accurately weighed according to the following weight ratios: 44 parts rheology modifier (30 parts fly ash, 14 parts ultrafine stone powder), 8 parts fiber thickening component (4 parts chopped polyvinyl alcohol fiber, 4 parts polyacrylonitrile fiber), 15 parts water-retaining thickening component (2 parts polyethylene oxide, 13 parts bentonite), and 4 parts nano-reinforcing additive (4 parts nano-calcium carbonate). These components are then added to a biaxial high-speed disperser and dispersed at 1000–1400 r / min for 5 min. The mixture is then placed in a gravity mixer, and simultaneously weighed according to the following weight ratios: 9 parts water-resistant component (9 parts chloroprene-ethylene-vinyl laurate powder) and 20 parts early-strength component (20 parts ultrafine ordinary silicate cement). These components are then added to the gravity mixer and mixed together at 20–40 r / min for 10 min to obtain the water-resistant rebound-inhibiting thickener.

[0033] Example 3

[0034] This embodiment provides a water-resistant rebound inhibitor and thickener. The components are accurately weighed according to the following weight proportions: 48 parts of rheology modifier (28 parts fly ash and 20 parts mineral powder), 10 parts of fiber thickening component (10 parts lignin fiber), 3 parts of water-retaining thickening component (3 parts hydroxypropyl methylcellulose), and 1 part of nano-reinforcing agent (1 part nano-SiO2). These components are then added to a biaxial high-speed disperser and dispersed at 1000–1400 r / min for 5 min. The mixture is then placed in a gravity mixer, and simultaneously weighed according to the following weight proportions: 2 parts of water-resistant component (2 parts ethylene-vinyl acetate powder) and 36 parts of early-strength component (30 parts ultrafine ordinary silicate cement and 6 parts C3S micro powder). These components are then added to the gravity mixer and mixed together at 20–40 r / min for 10 min to obtain the water-resistant rebound inhibitor and thickener.

[0035] Example 4

[0036] This embodiment provides a water-resistant rebound inhibitor and thickener. The components are accurately weighed according to the following weight proportions: 27 parts rheology modifier (27 parts microspheres), 9 parts fiber thickening component (7 parts chopped polyvinyl alcohol fiber and 2 parts lignin fiber), 32.5 parts water-retaining thickening component (32.5 parts bentonite), and 5.5 parts nano-reinforcing agent (5.5 parts nano-calcium carbonate). These components are then added to a biaxial high-speed disperser and dispersed at 1000–1400 r / min for 5 min. The mixture is then placed in a gravity mixer, and simultaneously weighed according to the following weight proportions: 6 parts water-resistant component (3 parts ethylene-vinyl acetate powder and 3 parts chloroprene-ethylene-vinyl laurate powder) and 20 parts early-strength component (20 parts sulfoaluminate cement). The mixture is then mixed together at 20–40 r / min for 10 min to obtain the water-resistant rebound inhibitor and thickener.

[0037] The thickeners used in Examples 5 and 6 were the same as those in Example 3, the difference being the dosage of the thickener in the concrete. The water-resistant rebound-inhibiting thickeners obtained in each example were used to prepare shotcrete. The mix proportions and performance test results of the shotcrete are shown in Tables 1-3. Specifically, the concrete slump, spread, and bleeding rate were determined according to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures," the compressive strength was determined according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete," and the arch crown rebound rate was determined according to JGJ / T 372-2016 "Technical Specification for Application of Shotcrete."

[0038] Table 1 Shotcrete mix proportions (kg / m³) 3 )

[0039]

[0040] Table 2. Test results of shotcrete performance

[0041]

[0042] Table 3. Effect of different water-resistant rebound inhibitor dosages on the performance of shotcrete

[0043]

[0044] Table 2 shows that the compressive strength of the shotcrete with the addition of a water-resistant rebound inhibitor was higher at all ages than that of the comparative example, while the rebound rate at the arch was lower. The rebound inhibition effect was as follows: Example 2 > Example 1 > Example 4 > Example 3. Example 2 showed the best effect because the water-resistant component, chloroprene-ethylene-vinyl laurate powder, has excellent water resistance, which can effectively improve the bonding strength and adhesion of concrete. Example 1 was the second best because it had the highest content of early-strength components, among which sulfoaluminate cement developed the fastest early strength, which was more conducive to the setting and hardening of concrete and inhibited concrete rebound to a certain extent. Example 3 had the worst effect because the water-resistant component was too small, and the traditional ethylene-vinyl acetate had limited effect on increasing the bonding ability of concrete. Even though the early-strength component content in the thickener was high, the poor water resistance and insufficient adhesion resulted in the highest concrete rebound rate.

[0045] Table 3 shows the effect of adding water-resistant rebound inhibitor to shotcrete according to the preparation method of Example 3, and testing the effect of different dosages on the performance of shotcrete.

[0046] The above tests show that the upper and lower limits and range values ​​of the water-resistant component, water-retaining and thickening component, fiber-adhesive component, rheology-enhancing component, early-strength component and nano-reinforcing additive of the present invention can achieve high water resistance, high adhesion and low rebound rate of shotcrete on the wet rock walls of water-rich tunnels.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The solutions disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments; relevant parts can be found in the method section.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A water-resistant rebound inhibitory tackifier, characterized in that, It includes the following components in parts by weight: 2-11.5 parts of water-resistant component, 3-32.5 parts of water-retaining and thickening component, 5-10 parts of fiber-adhesive component, 25-50 parts of rheology-enhancing component, 20-40 parts of early strength component, and 1-5.5 parts of nano-reinforcing agent; The water-resistant component is selected from one or a combination of two of ethylene-vinyl acetate powder, fluoropolyacrylate powder, and chloroprene-ethylene-vinyl laurate powder. The fiber thickening component is selected from one or a combination of two of chopped polyvinyl alcohol fibers, lignin fibers, polypropylene fibers, and polyacrylonitrile fibers; The lengths of the chopped polyvinyl alcohol fibers, polypropylene fibers, and polyacrylonitrile fibers are all 2mm-5mm. The length of the lignin fiber is 1mm-2mm; The water-retaining and thickening component is selected from one or a combination of two of polyacrylamide, polyethylene oxide, hydroxypropyl methylcellulose, and bentonite; The rheology enhancement component is selected from one or a combination of two of fly ash, microspheres, mineral powder, silica fume, and ultrafine stone powder; The early strength component is selected from one or a combination of two of sulfoaluminate cement, C3S micro powder, and ultrafine ordinary Portland cement. The nano-reinforcing agent is selected from one of nano-CSH gel, nano-SiO2, and nano-calcium carbonate.

2. The water-resistant rebound inhibitor and tackifier according to claim 1, characterized in that, The polyacrylamide has a weight-average molecular weight of 4 million to 12 million. The weight-average molecular weight of the polyethylene oxide is 800,000 to 5,000,000. The weight-average molecular weight of the hydroxypropyl methylcellulose is 5,000 to 100,000.

3. The water-resistant rebound inhibitor and tackifier according to claim 1, characterized in that, The fly ash is Class I fly ash; The content of particles with a diameter of less than 10 μm in the microspheres is ≥90%; The specific surface area of ​​the mineral powder is ≥500m². 2 / kg; The silica content of the silica ash is ≥90%; The specific surface area of ​​the ultrafine stone powder is ≥600m². 2 / kg.

4. The water-resistant rebound inhibitor and tackifier according to claim 1, characterized in that, The C3S micro powder is of industrial grade; The specific surface area of ​​the ultrafine ordinary Portland cement is 600 m². 2 / kg~900m 2 / kg.

5. A method for preparing a water-resistant rebound-inhibiting tackifier, characterized in that, Includes the following steps: (1) Weigh each component of the water-resistant rebound inhibitor according to any one of claims 1-4; (2) The rheology modifier, fiber thickening agent, water-retaining thickening agent and nano-reinforcing agent are added to a biaxial high-speed disperser and dispersed at 1000~1400 r / min for 5 min to obtain a mixture; (3) Add the mixture obtained in step (2) into a gravity mixer, and add water-resistant components and early strength components at the same time. Mix them together at 20~40 r / min for 10 min to obtain a water-resistant rebound inhibitor thickener.

6. The application of a water-resistant rebound inhibitory tackifier, characterized in that, The application of the water-resistant rebound inhibitor and tackifier according to any one of claims 1-4 or the water-resistant rebound inhibitor and tackifier prepared by the preparation method according to claim 5 in the production of shotcrete for water-rich tunnels.

7. A method of using a water-resistant rebound inhibitor and tackifier, characterized in that, The water-resistant rebound inhibitor and thickener described in any one of claims 1-4 or the water-resistant rebound inhibitor and thickener prepared by the preparation method described in claim 5 shall be added together with cement during the production of shotcrete. The amount added per cubic meter of concrete is 10kg to 30kg, replacing cement by the same weight.

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