Rapid-setting, quick-setting, adhesive-form shotcrete, its preparation method, and its application in tunnels.

Abstract

This invention relates to a rapid-setting, quick-setting, and formwork-grown shotcrete, its preparation method, and its application in tunnels. The rapid-setting, quick-setting, and formwork-grown shotcrete is composed of 380-420 parts of rapid-hardening sulfoaluminate cement, 40-50 parts of glass microspheres, 10-20 parts of modified lithium salt, 40-50 parts of modified attapulgite, 10-20 parts of polyacrylamide, 40-50 parts of carbon fiber, 40-50 parts of powdered petroleum wax, 800-860 parts of manufactured sand, 860-900 parts of manufactured crushed stone, and 170-180 parts of water. During construction, the prepared shotcrete is transported to a shotcrete machine with a formwork, and the slurry is appropriately heated before being sprayed onto the tunnel working surface through a nozzle for rapid curing. The shotcrete provided by this invention has the advantages of convenient transportation, high construction efficiency, precise temperature control, and stable performance. Its initial setting time is shortened to 60-90 seconds, its compressive strength reaches 10-13 MPa after 8 hours, its bond strength with the surrounding rock can reach 1.5-3.0 MPa, and its impermeability grade can reach P8. It has good application prospects in various projects, including tunnel construction.

Description

Technical Field

[0001] This invention relates to the field of inorganic non-metallic materials and tunnel construction technology, specifically to a fast-setting, quick-setting sprayed concrete, its preparation method, and its application in tunnels. Background Technology

[0002] Compared to surface construction, tunnel construction typically requires rapid support, placing higher demands on the early strength and rapid setting performance of concrete. The damp internal environment also imposes higher requirements and standards on the durability and impermeability of concrete. To achieve efficient tunnel construction and good mechanical properties, impermeability, and durability of tunnel concrete, it is essential to select appropriate processes, minimize the initial setting time of concrete, increase the viscosity between the concrete and the sprayed surface, and ensure the workability of the concrete. Against this backdrop, the application of shotcrete technology in tunnel construction holds great promise.

[0003] Shotcrete technology relies primarily on shotcrete, which, under the influence of compressed air or other power sources, propels a mixture of cementitious materials and aggregates in a specific ratio onto the surface of rock or a building at high speed. With the aid of a quick-setting agent, it hardens and solidifies rapidly, forming a concrete structure that provides both sealing and support. However, traditional shotcrete construction suffers from numerous problems in large-scale tunnel construction, including long construction times, high costs, significant material waste, poor concrete viscosity, high rebound rate, and low strength and durability.

[0004] A search revealed that some scholars have disclosed an early-strength liquid accelerator and its preparation method (CN115636615A). This method involves adding a modified calcium silicate crystal solution to an alcoholized alkaline alumina sol, and after reacting for 3-4 hours, an early-strength liquid accelerator is obtained. Other scholars have disclosed a liquid thickener for shotcrete, its preparation method, and its application (CN117886544A). This method improves the adhesiveness of latex powder through modification, thereby increasing the viscosity of the slurry. Analysis shows that while these existing solutions overcome problems such as long initial setting time and poor workability to some extent, they negatively impact the workability and setting time of concrete, and are generally costly.

[0005] Against this backdrop, shotcrete technology shows promise in tunnel construction. Shotcrete technology combines the advantages of formwork fixation and wet shotcrete construction. It utilizes a shotcrete machine with a formwork to spray concrete, which then quickly solidifies onto the tunnel wall, expanding the working face as the machine advances. Shotcrete offers stable quality, high construction efficiency, and high strength and durability. Its slump is typically 8–16 cm, its bond strength with the surrounding rock is typically 0.5–2.0 MPa, its impermeability grade is typically P6, and its initial setting time after adding a quick-setting agent is typically 2–3 minutes. It is generally a two-component shotcrete application, with an 8-hour compressive strength of 6–9 MPa, a 24-hour compressive strength of 9–15 MPa, and a 28-day compressive strength of 30–33 MPa. In tunnel construction, the concrete lining in the initial support stage needs to quickly reach near initial setting to provide sufficient support and prevent deformation of the surrounding rock. A slightly longer initial setting time can lead to cracking and deformation of the concrete lining due to changes in temperature and humidity inside the tunnel, posing a serious threat to tunnel construction and the safety of construction workers.

[0006] Therefore, developing a quick-setting, fast-bonding, early-strength, impermeable, and efficient sprayed concrete, and ensuring its good stability and applicability in different tunnel environments, is a technical challenge that urgently needs to be solved. Summary of the Invention

[0007] One of the objectives of this invention is to solve the aforementioned problems in the prior art and provide a fast-setting, quick-setting sprayed concrete, the composition of which includes cement, glass microspheres, lithium salt, attapulgite clay, polyacrylamide, carbon fiber, powdered petroleum wax, manufactured sand, manufactured crushed stone, and water.

[0008] Furthermore, the composition of this fast-setting, quick-setting, adhesive-molded sprayed concrete by weight is as follows: 380-420 parts cement, 40-50 parts glass microspheres, 10-20 parts lithium salt, 40-50 parts attapulgite, 10-20 parts polyacrylamide, 40-50 parts carbon fiber, 40-50 parts powdered petroleum wax, 800-860 parts manufactured sand, 860-900 parts manufactured crushed stone, and 170-180 parts water.

[0009] Furthermore, the cement is specifically rapid-hardening sulfoaluminate cement, the lithium salt is specifically modified lithium salt, and the attapulgite is specifically modified attapulgite.

[0010] Furthermore, the preparation process of the modified lithium salt is as follows: poly(N-isopropylacrylamide), lithium salt and water are mixed evenly, heated to react and then the water is removed to obtain the modified lithium salt.

[0011] Furthermore, the preparation process of the modified attapulgite is as follows: attapulgite and limestone are mixed evenly, then heated to 600-750℃, naturally cooled, and sieved to obtain modified attapulgite.

[0012] The second objective of this invention is to provide a method for preparing the above-mentioned fast-setting and quick-adhesion sprayed concrete, comprising: (a) mixing raw materials other than water evenly according to the formula to obtain dry material; (b) mixing the dry material and water evenly to obtain fast-setting and quick-adhesion sprayed concrete slurry.

[0013] Furthermore, in steps (a) and (b), mixing is carried out by stirring, with a stirring speed not exceeding 60 r / min and a stirring time not exceeding 10 min.

[0014] The third objective of this invention is to provide the application of the aforementioned fast-setting and quick-setting shotcrete in tunnel construction.

[0015] Furthermore, the specific application method is as follows: the fast-setting and quick-setting sprayed concrete slurry is transported to the spraying machine with a template, and the slurry is sprayed onto the tunnel working surface through the nozzle to quickly solidify.

[0016] Furthermore, the nozzle is flat, and the two sides of the nozzle are rounded.

[0017] Furthermore, the quick-setting, fast-adhesive sprayed concrete slurry needs to be heated to 32℃-35℃ before spraying.

[0018] Furthermore, the specific method for heating the slurry is as follows: a heating device is installed upstream of the nozzle, specifically an electric heater or a microwave heater.

[0019] Furthermore, the heating device is preferably an annular microwave heater, which is mounted on the material conveying pipeline.

[0020] Furthermore, the spraying speed of the fast-setting, quick-setting, adhesive-fit shotcrete slurry is 10–15 m / s.

[0021] Compared with existing similar products or technologies, the advancements of this invention are mainly reflected in the following aspects:

[0022] (1) Rapid setting and adhesion, early strength and impermeability. The novel sprayed concrete provided by this invention is composed of rapid-hardening sulfoaluminate cement, glass microspheres, modified lithium salt, modified attapulgite, polyacrylamide, carbon fiber, powdered petroleum wax, manufactured sand, manufactured crushed stone and water. The modified lithium salt forms aggregates with poly(N-isopropylacrylamide), thereby fixing the lithium salt molecules and preventing excessive early contact between lithium salt and rapid-hardening sulfoaluminate cement, which would affect the spraying process. When the concrete slurry is heated to 32-35°C before spraying, the lithium salt gradually dissolves, accelerating the hydration process, shortening the initial setting time to 60-90 seconds and improving early strength; the compressive strength can reach 10-13 MPa after 8 hours. The polyacrylamide molecules in the raw materials carry negative charges, which can adsorb positive charges in the concrete system, thereby improving the viscosity of the concrete and enhancing its impermeability. Test results show that the bond strength between this sprayed concrete and the surrounding rock can reach 1.5-3.0 MPa, and the impermeability grade can reach P8.

[0023] (2) Convenient transportation and efficient construction. This invention enhances the plasticity of concrete with modified attapulgite and also utilizes the "ball bearing" effect of glass microspheres. Modified attapulgite is obtained by calcining attapulgite and limestone and then screening. The calcined attapulgite has an inorganic thickening effect, thus improving the plasticity of concrete. Calcium hydroxide is generated when calcined limestone comes into contact with water. The layered calcium hydroxide crystals act as a lubricant, and the reaction releases a large amount of heat, accelerating hydration and setting. The smooth surface of the glass microspheres reduces the frictional resistance of the concrete system, making it easier to flow and facilitating the transportation of shotcrete in the spraying equipment. In addition, glass microspheres can fill the voids inside the concrete, improving its density and strength. By using modified attapulgite and glass microspheres in combination, the adverse effects on the workability of concrete caused by the extremely short initial setting time are solved, ensuring excellent concrete plasticity, smooth spraying, and a slump of 20-23 cm.

[0024] (3) Precise temperature control and stable operation. This invention uses carbon fiber and powdered petroleum wax as microwave absorbing and temperature controlling materials, respectively. During microwave heating, the carbon fiber heats up at a rate of approximately 1.0–1.2 °C / s, which can rapidly increase the concrete temperature by 10–40 °C. Meanwhile, the powdered petroleum wax absorbs latent heat and undergoes a phase change when the concrete temperature exceeds 40 °C, preventing the concrete temperature from becoming too high. Through the synergistic use of carbon fiber and powdered petroleum wax, the obstacles to the initial hydration and setting of concrete caused by the damp and cold environment of tunnels are solved, and the concrete temperature can be precisely controlled, giving the shotcrete good stability and applicability in different tunnel environments.

[0025] (4) Single-component spraying. This invention improves and innovates the spray nozzle for molded concrete. The nozzle is flat, which can produce a wider spraying surface, enabling large-area, rapid, and efficient spraying. Furthermore, a ring-shaped microwave heater is installed upstream of the specially designed nozzle, with a length of 20-30cm, a distance of 20-40cm from the nozzle, a microwave power of 80-100kW, and a microwave frequency of 2.45GHz. This ring-shaped microwave heater heats the concrete slurry delivered to the nozzle, ensuring that lithium salts gradually dissolve from the aggregates and react rapidly with the homogeneous mixing of the rapid-hardening sulfoaluminate cement. This design adapts to the short initial setting time of molded concrete, allowing spraying to be completed using a single nozzle, thus changing the conventional operation of two-component spraying. Detailed Implementation

[0026] To enable those skilled in the art to fully understand the technical solution and beneficial effects of the present invention, the following detailed description is provided in conjunction with specific embodiments.

[0027] The formula of the fast-setting and quick-setting sprayed concrete for tunnels provided by this invention, by weight parts, is as follows: 380-420 parts of rapid-hardening sulfoaluminate cement, 40-50 parts of glass microspheres, 10-20 parts of modified lithium salt, 40-50 parts of modified attapulgite, 10-20 parts of polyacrylamide, 40-50 parts of carbon fiber, 40-50 parts of powdered petroleum wax, 800-860 parts of manufactured sand, 860-900 parts of manufactured crushed stone, and 170-180 parts of water.

[0028] The modified lithium salt is prepared as follows: Poly(N-isopropylacrylamide) and lithium salt are separately mixed with deionized water to prepare solutions with a concentration of 0.5%-1%. The aqueous solutions of poly(N-isopropylacrylamide) and lithium salt are mixed uniformly at a mass ratio of 1:1 to 3:1 at 15-20°C. The resulting mixture is heated to 32-35°C at a heating rate of 2-5°C / min under air atmosphere and held at this temperature for 0.5-2 hours. During this period, poly(N-isopropylacrylamide) undergoes a phase transition and forms aggregates with the lithium salt, thereby fixing the lithium salt molecules. The mixture is then cooled to 15-26°C, and solid-liquid separation is performed using vacuum filtration or pressure filtration. The separated solid is washed 2-3 times with a small amount of deionized water. The washed modified lithium salt solid is evenly spread in a drying tray with a thickness not exceeding 6 mm, and then placed in a constant temperature oven at 15-26°C for forced-air drying for 24-48 hours, thus obtaining the modified lithium salt. The raw material lithium salt can be one or more of lithium carbonate, lithium sulfate, lithium chloride, lithium nitrate, lithium hydroxide, etc., and the purity of the modified lithium salt obtained is above 99%.

[0029] The preparation method of modified attapulgite is as follows: Attapulgite and limestone are mixed evenly in a mass ratio of 2:1 to 4:1. The resulting mixture is heated to 600 to 750°C in air at a heating rate of 5-20°C / min and held for 10-30 minutes. Then it is naturally cooled to room temperature and sieved through a 100-200 mesh sieve to obtain modified attapulgite.

[0030] After weighing the raw materials according to the above proportions, add glass microspheres, carbon fiber, polyacrylamide, modified lithium salt, powdered petroleum wax, manufactured sand, manufactured crushed stone, rapid-hardening sulfoaluminate cement, and modified attapulgite clay into the mixing pot in sequence. Start the mixing device and dry mix at a speed of 30-60 r / min for 2-5 minutes. Then add water and mix at the same speed for 1-3 minutes to obtain a fast-setting and quick-adhesion sprayed concrete slurry.

[0031] After the rapid-setting, quick-setting sprayed concrete slurry is prepared, it is piped to a spraying machine with a template. The slurry is sprayed from the nozzle at a speed of 10–15 m / s and cures rapidly. To ensure sufficient dissolution of lithium salt and reaction with fast-setting sulfoaluminate cement, a 20–30 cm long annular microwave heater with a microwave frequency of 2.45 GHz is installed 20–40 cm from the nozzle in the direction of material inflow. This allows the slurry temperature to be controlled at 32℃–35℃. To obtain a wide spraying surface and achieve large-area, rapid, and efficient spraying, the nozzle is designed to be flat, with arcs on both sides of the nozzle having a radius of 2–3 cm. The maximum width of the nozzle is 10–12 cm, and the height is 4–6 cm.

[0032] Example 1

[0033] The formula for rapid-setting, quick-setting shotcrete for tunnels provided in this embodiment is as follows: 390 parts rapid-hardening sulfoaluminate cement, 44 parts glass microspheres, 16 parts modified lithium salt, 44 parts modified attapulgite, 16 parts polyacrylamide, 44 parts carbon fiber, 46 parts powdered petroleum wax, 820 parts manufactured sand, 880 parts manufactured crushed stone, and 172 parts water. The preparation method of this rapid-setting, quick-setting shotcrete for tunnels is as follows:

[0034] S1. Add glass microspheres, carbon fiber, polyacrylamide, modified lithium salt, powdered petroleum wax, manufactured sand, manufactured crushed stone, rapid hardening sulfoaluminate cement, and modified attapulgite clay into a mixing pot in sequence according to the proportion, and dry mix at a speed of 30 r / min for 2 min to obtain a uniformly mixed dry material.

[0035] S2. Add water to the dry material described in step S1 and stir at 30 r / min for 1 min to obtain a slurry;

[0036] S3. After heating the slurry described in step S2 to 32℃-35℃, it is sprayed out from the nozzle at a speed of 10m / s, and the slurry solidifies rapidly on the tunnel working surface.

[0037] Example 2

[0038] The formula for the quick-setting and quick-adhesion shotcrete for tunnels provided in this embodiment is as follows: 404 parts of rapid-hardening sulfoaluminate cement, 42 parts of glass microspheres, 14 parts of modified lithium salt, 44 parts of modified attapulgite, 16 parts of polyacrylamide, 44 parts of carbon fiber, 46 parts of powdered petroleum wax, 830 parts of manufactured sand, 870 parts of manufactured crushed stone, and 175 parts of water.

[0039] S1. Add glass microspheres, carbon fiber, polyacrylamide, modified lithium salt, powdered petroleum wax, manufactured sand, manufactured crushed stone, rapid hardening sulfoaluminate cement, and modified attapulgite clay into a mixing pot in sequence according to the proportion, and dry mix at a speed of 60 r / min for 3 min to obtain a uniformly mixed dry material.

[0040] S2. Add water to the dry material described in step S1 and stir at 60 r / min for 3 min to obtain a slurry;

[0041] S3. After heating the slurry described in step S2 to 32℃-35℃, it is sprayed out from the nozzle at a speed of 15m / s, and the slurry solidifies rapidly on the tunnel working surface.

[0042] Example 3

[0043] The formula for the quick-setting and quick-adhesion shotcrete for tunnels provided in this embodiment is as follows: 410 parts of rapid-hardening sulfoaluminate cement, 46 parts of glass microspheres, 17 parts of modified lithium salt, 46 parts of modified attapulgite, 13 parts of polyacrylamide, 46 parts of carbon fiber, 43 parts of powdered petroleum wax, 845 parts of manufactured sand, 880 parts of manufactured crushed stone, and 176 parts of water.

[0044] S1. Add glass microspheres, carbon fiber, polyacrylamide, modified lithium salt, powdered petroleum wax, manufactured sand, manufactured crushed stone, rapid hardening sulfoaluminate cement, and modified attapulgite clay into a mixing pot in sequence according to the proportion, and dry mix at a speed of 50 r / min for 4 min to obtain a uniformly mixed dry material.

[0045] S2. Add water to the dry material described in step S1 and stir at a speed of 40 r / min for 2 minutes to obtain a slurry;

[0046] S3. The slurry described in step S2 is heated to 32℃-35℃ and then sprayed out from the nozzle at a speed of 12m / s. The slurry solidifies rapidly on the tunnel working surface.

[0047] Example 4

[0048] The formula for the quick-setting and quick-adhesion shotcrete for tunnels provided in this embodiment is as follows: 386 parts of rapid-hardening sulfoaluminate cement, 42 parts of glass microspheres, 15 parts of modified lithium salt, 45 parts of modified attapulgite, 15 parts of polyacrylamide, 45 parts of carbon fiber, 47 parts of powdered petroleum wax, 837 parts of manufactured sand, 886 parts of manufactured crushed stone, and 174 parts of water.

[0049] S1. Add glass microspheres, carbon fiber, polyacrylamide, modified lithium salt, powdered petroleum wax, manufactured sand, manufactured crushed stone, rapid hardening sulfoaluminate cement, and modified attapulgite clay into a mixing pot in sequence according to the proportion, and dry mix at a speed of 50 r / min for 4 min to obtain a uniformly mixed dry material.

[0050] S2. Add water to the dry material described in step S1 and stir at 30 r / min for 2 min to obtain a slurry;

[0051] S3. The slurry described in step S2 is heated to 32℃-35℃ and then sprayed out from the nozzle at a speed of 14m / s. The slurry solidifies rapidly on the tunnel working surface.

[0052] Example 5

[0053] The formula for the quick-setting and quick-adhesion sprayed concrete for tunnels provided in this embodiment is as follows: 415 parts of rapid-hardening sulfoaluminate cement, 44 parts of glass microspheres, 14 parts of modified lithium salt, 48 parts of modified attapulgite, 17 parts of polyacrylamide, 42 parts of carbon fiber, 47 parts of powdered petroleum wax, 825 parts of manufactured sand, 867 parts of manufactured crushed stone, and 177 parts of water.

[0054] S1. Add glass microspheres, carbon fiber, polyacrylamide, modified lithium salt, powdered petroleum wax, manufactured sand, manufactured crushed stone, rapid hardening sulfoaluminate cement, and modified attapulgite clay into a mixing pot in sequence according to the proportion, and dry mix at a speed of 40 r / min for 3 min to obtain a uniformly mixed dry material.

[0055] S2. Add water to the dry material described in step S1 and stir at 50 r / min for 3 min to obtain a slurry;

[0056] S3. The slurry described in step S2 is heated to 32℃-35℃ and then sprayed out from the nozzle at a speed of 13m / s. The slurry solidifies rapidly on the tunnel working surface.

[0057] Example 6

[0058] The formula for the quick-setting and quick-adhesion shotcrete for tunnels provided in this embodiment is as follows: 400 parts of rapid-hardening sulfoaluminate cement, 48 parts of glass microspheres, 12 parts of modified lithium salt, 48 parts of modified attapulgite, 18 parts of polyacrylamide, 42 parts of carbon fiber, 42 parts of powdered petroleum wax, 855 parts of manufactured sand, 870 parts of manufactured crushed stone, and 179 parts of water.

[0059] S1. Add glass microspheres, carbon fiber, polyacrylamide, modified lithium salt, powdered petroleum wax, manufactured sand, manufactured crushed stone, rapid hardening sulfoaluminate cement, and modified attapulgite clay into a mixing pot in sequence according to the proportion, and dry mix at a speed of 40 r / min for 5 min to obtain a uniformly mixed dry material.

[0060] S2. Add water to the dry material described in step S1 and stir at 30 r / min for 3 min to obtain a slurry;

[0061] S3. The slurry described in step S2 is heated to 32℃-35℃ and then sprayed out from the nozzle at a speed of 11m / s. The slurry solidifies rapidly on the tunnel working surface.

[0062] Comparative Example 1

[0063] The difference between this comparative example and Example 1 is that this comparative example does not use modified lithium salt. In order to ensure that the proportions of other components remain unchanged, 16 parts of modified lithium salt are replaced with 16 parts of manufactured sand.

[0064] The formula for the quick-setting, quick-setting sprayed concrete for tunnels provided in this comparative example is as follows: 390 parts of rapid-hardening sulfoaluminate cement, 44 parts of glass microspheres, 44 parts of modified attapulgite, 16 parts of polyacrylamide, 44 parts of carbon fiber, 46 parts of powdered petroleum wax, 836 parts of manufactured sand, 880 parts of manufactured crushed stone, and 172 parts of water.

[0065] Comparative Example 2

[0066] The difference between this comparative example and Example 2 is that this comparative example does not use modified attapulgite. In order to ensure that the proportions of other components remain unchanged, 44 parts of modified attapulgite are replaced with 44 parts of manufactured sand.

[0067] The formula for the quick-setting and quick-adhesion shotcrete for tunnels provided in this embodiment is as follows: 404 parts of rapid-hardening sulfoaluminate cement, 42 parts of glass microspheres, 14 parts of modified lithium salt, 16 parts of polyacrylamide, 44 parts of carbon fiber, 46 parts of powdered petroleum wax, 874 parts of manufactured sand, 870 parts of manufactured crushed stone, and 175 parts of water.

[0068] Comparative Example 3

[0069] The difference between this comparative example and Example 3 is that this comparative example does not use polyacrylamide. In order to ensure that the proportions of other components remain unchanged, 13 parts of polyacrylamide are replaced with 13 parts of manufactured sand.

[0070] The formula for the quick-setting and quick-adhesion sprayed concrete for tunnels provided in this embodiment is as follows: 410 parts of rapid-hardening sulfoaluminate cement, 46 parts of glass microspheres, 17 parts of modified lithium salt, 46 parts of modified attapulgite, 46 parts of carbon fiber, 43 parts of powdered petroleum wax, 858 parts of manufactured sand, 880 parts of manufactured crushed stone, and 176 parts of water.

[0071] The initial setting time, bond strength with surrounding rock, slump, 8-hour compressive strength, and impermeability grade of the fast-setting, quick-setting shotcrete for tunnels prepared in Examples 1-6 and Comparative Examples 1-3 were tested. The setting time test was conducted according to GB / T 1346-2011 "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement", the bond strength test was conducted according to JGJ / T 372-2016 "Technical Specification for Application of Shotcrete", the slump test was conducted according to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", the 8-hour compressive strength test was conducted according to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", and the specimen size was 150mm×150mm×150mm. The impermeability grade test was conducted according to GB50164-2011 "Standard for Quality Control of Concrete". The specific test results are shown in the table below.

[0072] Table 1. Performance Comparison of Shotcrete Prepared in Different Embodiments

[0073]

[0074] As shown in the table above, ① the initial setting time and 8-hour compressive strength of the quick-setting shotcrete for tunnels using modified lithium salt (Examples 1-6, Comparative Examples 2 and 3) are significantly better than those of the quick-setting shotcrete for tunnels without modified lithium salt (Comparative Example 1). This indicates that modified lithium salt can accelerate the hydration process, shorten the initial setting time to 60-90 seconds, and improve early strength. ② The slump of the quick-setting shotcrete for tunnels using modified attapulgite soil (Examples 1-6, Comparative Examples 1 and 3) is significantly greater than that of the quick-setting shotcrete for tunnels without modified attapulgite soil (Comparative Example 2). This demonstrates that modified attapulgite soil has an inorganic thickening effect, which can improve the plasticity of concrete. ③ The bonding strength and impermeability grade of the quick-setting sprayed concrete for tunnels using polyacrylamide (Examples 1-6, Comparative Examples 1 and 2) are significantly better than those of the quick-setting sprayed concrete for tunnels without polyacrylamide (Comparative Example 3). This is because the molecular chain of polyacrylamide carries a negative charge, which can adsorb the positive charge in the concrete system, improve the viscosity of the concrete, and enhance its impermeability.

[0075] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit and essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of the equivalents of the claims be included within the present invention.

Claims

1. A type of fast-setting, quick-setting, adhesive-form sprayed concrete, characterized in that: The composition of this fast-setting, quick-setting, adhesive-formed sprayed concrete by weight includes: 380-420 parts cement, 40-50 parts glass microspheres, 10-20 parts modified lithium salt, 40-50 parts modified attapulgite, 10-20 parts polyacrylamide, 40-50 parts carbon fiber, 40-50 parts powdered petroleum wax, 800-860 parts manufactured sand, 860-900 parts manufactured crushed stone, and 170-180 parts water. The modified lithium salt is prepared by mixing poly(N-isopropylacrylamide), lithium salt, and water evenly, heating and reacting, and then removing the water to obtain the modified lithium salt. The modified attapulgite is prepared by mixing attapulgite and limestone evenly, then heating to 600-750℃, naturally cooling, and then sieving to obtain the modified attapulgite.

2. The fast-setting, quick-setting, adhesive-form sprayed concrete as described in claim 1, characterized in that: The cement is specifically rapid-hardening sulfoaluminate cement.

3. The method for preparing fast-setting, quick-setting, adhesive-molding shotcrete according to any one of claims 1-2, characterized in that... The method includes: mixing raw materials other than water evenly to obtain a dry material, mixing the dry material with water evenly to obtain a fast-setting, quick-adhesion sprayed concrete slurry.

4. The application of the fast-setting, quick-setting shotcrete as described in any one of claims 1-2 in tunnel construction.

5. The application as described in claim 4, characterized in that... The specific process of this application is as follows: the fast-setting and quick-setting sprayed concrete slurry is transported to the spraying machine with the template, and the slurry is sprayed onto the tunnel working surface through the nozzle to solidify quickly.

6. The application as described in claim 5, characterized in that: The nozzle is flat and has rounded sides.

7. The application as described in claim 5, characterized in that: The quick-setting, fast-adhesive sprayed concrete slurry needs to be heated to 32℃-35℃ before spraying.

8. The application as described in claim 7, characterized in that... The slurry heating is achieved by installing a heating device upstream of the nozzle, which is specifically an electric heater or a microwave heater, and the heating device is fitted onto the conveying pipeline.

9. The application as described in claim 5, characterized in that: The spraying speed of fast-setting, quick-setting, adhesive-fit shotcrete slurry is 10~15m / s.

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