A shotcrete spraying performance test device and method

Abstract

The invention discloses a spraying performance test device and method for shotcrete. The device comprises a rotational viscometer, which is movably connected to the upper surface of a slurry bin, a plurality of air compression pipe interfaces are arranged on the upper surface of the slurry bin, a partition bin part is located in the slurry bin and can move up and down in the slurry bin, one end of a spraying pipe adapter is connected to the bottom surface of the slurry bin, and the other end is connected to the spraying pipe, and a plurality of brackets are connected to the slurry bin for supporting the slurry bin; when the rotational viscometer is removed from the slurry bin, a cover plate can be movably installed on the upper surface of the slurry bin; the invention can determine whether the spraying performance of freshly mixed concrete meets the application requirements of the project by test and judgment, and can provide guidance for the formulation of spraying construction process parameters such as spraying pressure and spraying pipe size on the other hand.

Description

Technical Field

[0001] The invention relates to the technical field of shotcrete testing, and in particular to a shotcrete spraying performance testing device and method. Background Art

[0002] Shotcrete construction technology can save the tedious processes of formwork, casting, vibration and demoulding, and has the advantages of short construction period and convenient construction. It is often used in the repair and reinforcement of existing buildings and underground support projects. Compared with ordinary cast-in-place concrete, shotcrete has the disadvantages of high brittleness, low tensile strength, poor crack resistance and toughness. Therefore, many scholars add various fiber materials to concrete to achieve the purpose of toughening and crack control. However, the addition of fibers may affect the performance of concrete slurry and there is a risk of clogging the pipeline during concrete transportation. Fresh concrete that meets engineering applications must have good "pumpability" and "sprayability". "Pumpability" means that fresh concrete can be transported smoothly in the pumping pipeline without pipeline clogging, which means a smaller plastic viscosity to ensure that it can be "sprayed out" without segregation. "Sprayability" means that after the concrete is sprayed, it can adhere to the sprayed surface without collapsing, which means a larger static yield stress, ensuring that it can "hang" after being sprayed; good "pumpability" and "sprayability" require that the shotcrete be pumped smoothly during the spraying process, and that after being sprayed onto the working surface, it can form a dense structure without falling off and flowing.

[0003] At present, for the spraying performance test of shotcrete, the rheological properties such as static yield stress and plastic viscosity are generally determined by rheological performance testing. When the fresh concrete has a lower plastic viscosity, its "pumpability" can be guaranteed, and when the fresh concrete has a higher static yield stress, it can be guaranteed to form a dense structure without falling off and flowing after being sprayed onto the working surface. In laboratory research, a rotational viscometer is usually used to measure the rheological properties of the material. The advantage of a rotational viscometer is that it can accurately measure the rheological parameters of the material such as static yield stress and plastic viscosity, but it is impossible to evaluate the influence of the spraying construction process parameters such as spraying pressure and spraying pipe size on the spraying performance, and therefore it is impossible to determine the appropriate spraying construction process parameters through a rotational viscometer.

[0004] The utility model patent with announcement number CN204098930U discloses a spraying device for dry spraying concrete. The technical problem solved by the patent is the problem of concrete spraying, but it does not solve the problem of how to evaluate the concrete spraying performance, nor does it solve the problem of how to determine the appropriate spraying construction process parameters such as spraying pressure and spraying pipe size. Summary of the invention

[0005] The invention aims to provide a shotcrete spraying performance test device and method.

[0006] To achieve the above objectives, the technical solution of the present invention is:

[0007] A shotcrete spraying performance test device comprises a rotational viscometer and a slurry bin, wherein the partition bin is located in the slurry bin and can move up and down in the slurry bin; the lower end of the rotational viscometer can extend into the partition bin, and the upper end of the rotational viscometer is movably connected to the upper surface of the partition bin; a plurality of air pressure pipe interfaces are arranged on the upper surface of the slurry bin, one end of the spray pipe adapter is connected to the bottom surface of the slurry bin, and the other end is connected to the spray pipe, and a plurality of brackets are connected to the slurry bin for supporting the slurry bin; when the partition bin is moved out of the slurry bin, the cover plate is movably installed on the upper surface of the slurry bin;

[0008] A pressure gauge is fixed on the wall of the slurry bin, and the pressure gauge is used to monitor the air pressure value in the slurry bin;

[0009] A flow meter is fixed at the lower end of the injection pipe, and the flow meter is used to measure the flow rate of the concrete slurry.

[0010] Furthermore, there is an opening in the middle of the upper surface of the slurry bin, and the opening is adapted to the cylindrical partition bin. The cylindrical partition bin can move up and down along the opening, and the top end of the partition bin protrudes from the upper surface of the slurry bin.

[0011] Furthermore, the top of the partition chamber is open, and the open mouth is used to inject concrete into the partition chamber; the top open mouth of the partition chamber and the upper side surface of the rotational viscometer are both provided with threads, and the partition chamber is threadedly connected to the rotational viscometer.

[0012] Furthermore, a plurality of transparent observation holes are provided at the lower end of the side wall of the slurry bin, and the plurality of transparent observation holes are symmetrically arranged on the side wall of the slurry bin.

[0013] Furthermore, a through hole is arranged at the bottom of the slurry bin; the through hole is connected to one end of the injection pipe adapter, and the other end of the injection pipe adapter is connected to the injection pipe; an injection pipe adapter valve is arranged at one end of the injection pipe adapter close to the slurry bin.

[0014] Furthermore, the plurality of air compression pipe interfaces are evenly spaced apart on the upper surface of the slurry bin near the edge of the upper surface of the slurry bin.

[0015] Furthermore, when the partition bin is not placed in the slurry bin, the cover plate can be connected to the slurry bin, and the cover plate covers the central opening on the top surface of the slurry bin; an external thread is provided on the central opening on the top surface of the slurry bin, and an internal thread is provided on the edge of the cover plate, and the cover plate is threadedly connected to the slurry bin.

[0016] The method for conducting a concrete spraying performance test using the concrete spraying performance test device comprises the following steps:

[0017] S1: completely lower the partition bin in the slurry bin so that the bottom surface of the partition bin contacts the bottom surface of the slurry bin;

[0018] S2: Close the injection pipe adapter valve;

[0019] S3: injecting a certain volume of concrete into the compartment through the opening at the top of the compartment;

[0020] S4: Extend the lower end of the rotational viscometer into the compartment so that the lower end of the rotational viscometer contacts the concrete in the compartment, and measure the rheological properties by the rotational viscometer. At this time, the critical peak torque T of the concrete paste can be measured by the rotational viscometer. C ;

[0021] S5: Take out the rotational viscometer, stir the concrete slurry in the separation bin, open the injection pipe adapter valve, the concrete in the slurry bin flows out from the injection pipe, and record the time required for the concrete to flow out completely;

[0022] S6: Take the partition bin out of the slurry bin, close the injection pipe adapter valve again, cover the opening of the partition bin with a cover plate, inject compressed air into the slurry bin from multiple air compressor pipe interfaces, and inject fresh concrete into the slurry bin from the central through hole of the cover plate, and wait until the pressure in the slurry bin reaches the set value; open the injection pipe adapter valve to allow the concrete in the slurry bin to flow out from the injection pipe, and record the slurry flow rate through the flow meter on the injection pipe;

[0023] S7: Calculation of static yield stress τ of concrete s , rheological characteristic factor K1 and injection process factor K2;

[0024] S8: Determine whether the rheological characteristic factor K1 and the injection process factor K2 are within a preset range. If K1 and K2 are within the preset range, the freshly mixed concrete meets the engineering application requirements; if K1 and K2 are not within the preset range, the freshly mixed concrete does not meet the engineering application requirements.

[0025] Furthermore, in the step S7, the static yield stress of concrete τ s The calculation formula is as follows:

[0026]

[0027] Where: τ s - static yield stress of concrete;

[0028] T C —Slurry critical peak torque;

[0029] h—height of slurry bin;

[0030] R—Viscometer rotor radius;

[0031] The calculation formulas for rheological characteristic factor K1 and injection process factor K2 are as follows:

[0032]

[0033]

[0034] In formula (2) and formula (3):

[0035] τ s - static yield stress of concrete;

[0036] t—time for slurry to flow out completely;

[0037] v—slurry flow rate in the injection pipe;

[0038] P—air pressure;

[0039] d—inner diameter of the injection pipe;

[0040] l—Injection pipe length.

[0041] Furthermore, in the step S7, if the calculated K1 is not within the preset range, viscosity-increasing or viscosity-reducing materials are added to the concrete; if the calculated K2 is not within the preset range, the injection pressure, the inner diameter or the length of the injection pipe are adjusted so that the injection process factor K2 is within the preset range.

[0042] The beneficial effects of the present invention are:

[0043] 1. The present invention can test and determine whether the spraying performance of fresh concrete meets the application requirements of the project; the present invention sets the rheological characteristic factor K1 and the spraying process factor K2, and calculates the values ​​of the rheological characteristic factor K1 and the spraying process factor K2 through the device and method of the present invention. If the calculated K1 and K2 are within the preset range, the fresh concrete meets the application requirements of the project; if the calculated K1 and K2 are not within the preset range, the fresh concrete does not meet the application requirements of the project.

[0044] 2. This experimental method conducts experiments by changing actual spraying construction parameters such as spraying pressure and nozzle size. By measuring the above parameters and using the rheological characteristic factor K1 and spraying process factor K2 data obtained after adjusting the above spraying construction process parameters, a spraying performance test method is established, which can provide guidance for the formulation of spraying construction process parameters such as spraying pressure and spraying pipe size.

[0045] 3. The present invention can comprehensively evaluate the spraying performance of shotcrete; on the one hand, the static yield stress of the concrete slurry can be measured by a rotational viscometer, and the viscosity of the slurry can be characterized by the outflow time of the slurry, which is used to evaluate the "sprayability" and "pumpability" of the concrete; on the other hand, compared with the existing spraying performance test method, the present invention first simplifies the slurry rheological test steps, reduces the workload of the rheological performance test, and thus reduces the performance requirements of the test on the rotational viscometer, that is, the present invention can use a low-end rotational viscometer, thereby reducing the equipment purchase cost of the rotational viscometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the injection performance test device.

[0047] Figure 2 is a schematic diagram of a rotational viscometer.

[0048] Figure 3 This is a schematic diagram of the slurry silo.

[0049] Figure 4 This is a top view of the slurry silo.

[0050] Figure 5 This is a schematic diagram of the cover.

[0051] Figure 6 This is a schematic diagram of the injection pipe adapter.

[0052] Figure 7 It is a schematic diagram of the injection pipe.

[0053] Among them: 1—viscometer; 2—slurry bin; 3—injection pipe adapter; 4—injection pipe; 5—bracket; 6—cover plate; 11—digital display controller; 12—motor; 13—rotating shaft; 14—rotor; 21—air compressor pipe interface; 22—pressure gauge; 23—transparent observation hole; 24—slurry bin bottom; 25—through hole; 26—opening; partition bin—27; 31—injection pipe adapter external thread; 32—injection pipe adapter valve; 33—injection pipe adapter protrusion; 41—flow meter; 61—center through hole. DETAILED DESCRIPTION

[0054] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0055] like Figure 1 As shown, the spraying performance test device of the present invention includes a viscometer 1, a cylindrical slurry bin 2, a spraying pipe adapter 3, a spraying pipe 4, a plurality of brackets 5, and a cover plate 6.

[0056] like Figure 2 As shown, the viscometer 1 is a rotational viscometer, which includes a digital display controller 11, a motor 12, a rotating shaft 13, and a rotor 14. The motor 11 rotates at a stable speed, the motor 12 drives the rotating shaft 13 to rotate, and the rotating shaft 13 drives the rotor 14 to rotate. The resistance of the concrete encountered by the rotor during rotation is used to read the rheological performance parameters such as static yield stress and plastic viscosity on the digital display controller 11; the digital display controller 11 can be used as an operation interface for controlling the viscometer 1, and can also display the specific values ​​of indicators such as static yield stress and plastic viscosity measured by the viscometer 1.

[0057] like Figure 1 , Figure 3 and Figure 4 As shown, a plurality of air compressor pipe interfaces 21 are arranged on the upper surface of the cylindrical slurry bin 2, and the plurality of air compressor pipe interfaces 21 are evenly spaced at the upper surface of the slurry bin 2 near the edge of the upper surface of the slurry bin 2; an internal thread is arranged on the air compressor pipe interface 21, and the air compressor pipe can be threadedly connected to the air compressor pipe interface 21.

[0058] The pressure gauge 22 is fixed on the side wall of the slurry bin, specifically, an opening is set on the side wall of the slurry bin 2, and the pressure gauge 22 is sealed in the opening on the side wall of the slurry bin 2. The air pressure at the opening is balanced with the air pressure in the slurry bin 2, so the air pressure in the slurry bin 2 can be monitored by the pressure gauge 22.

[0059] There is an opening 26 in the center of the upper surface of the slurry bin 2, and the opening 26 is adapted to the cylindrical partition bin 27. The cylindrical partition bin 27 is movably connected to the slurry bin 2, and the partition bin 27 can move up and down along the opening 26. The top of the partition bin 27 protrudes from the upper surface of the slurry bin 2, and the top of the partition bin 27 is open, and concrete can be injected into the partition bin 27 from the open; the rotor 14 of the viscometer 1 can extend into the partition bin 27; the partition bin 27 can be made of a steel sheet.

[0060] A plurality of transparent observation holes 23 are provided at the lower end of the side wall of the slurry bin 2. The plurality of transparent observation holes 23 are symmetrically arranged on the side wall of the slurry bin 2. The transparent observation holes 23 are used to timely judge the amount of concrete slurry in the slurry bin 2. The transparent observation holes 23 are made of transparent material that can withstand a certain pressure and can be made of tempered glass.

[0061] A through hole 25 is arranged at the bottom of the slurry bin 2; an internal thread of an injection pipe adapter is arranged on the through hole 25, an external thread is arranged on the injection pipe adapter 3, and the through hole 25 is connected to the injection pipe adapter 3 through threads; the through hole 25 is connected to one end of the injection pipe adapter 3, the injection pipe adapter 3 is connected to the slurry bin 2 through the through hole 25, and the other end of the injection pipe adapter 3 is connected to the injection pipe 4; an injection pipe adapter valve 32 is arranged at one end of the injection pipe adapter 3 close to the slurry bin 2.

[0062] like Figure 6 As shown, an injection pipe adapter external thread 31 is provided at the top of the injection pipe adapter 3, an injection pipe adapter valve 32 is provided near the top of the injection pipe 3, and an injection pipe adapter protrusion 33 is provided at the bottom of the injection pipe adapter 3. The injection pipe adapter external thread 31 is threadedly connected with the through hole 25 to realize the connection between the slurry bin 2 and the injection pipe adapter 3; the injection pipe adapter protrusion 33 is connected with the injection pipe 4, and the injection pipe adapter protrusion 33 can be a thread or a buckle, which is used to connect the injection pipe 4 to realize the connection between the injection pipe 4 and the injection pipe adapter 3.

[0063] like Figure 7 As shown, a flow meter 41 is fixed at the lower end of the injection pipe 4, and the flow meter 41 is used to measure the flow rate of the concrete slurry. Specifically, an opening is set on the injection pipe, and the flow meter 41 is partially located outside the injection pipe 4 and partially located inside the injection pipe 4. When the concrete flows through the part where the flow meter 41 is located inside the injection pipe 4, the flow meter 41 can measure the flow rate of the concrete slurry.

[0064] The connection end of the injection pipe adapter 3 and the injection pipe 4 has various sizes to meet the actual needs of different injection pipe sizes; the inner diameter of the injection pipe in the present invention is recommended to be 30-100mm, and the length of the injection pipe is 10-25cm.

[0065] The outer surface of the slurry bin bottom 24 is connected to a plurality of brackets 5 , and the brackets 5 are used to support the slurry bin 2 .

[0066] When the partition bin 27 is not placed in the slurry bin 2, the cover plate 6 can be connected to the slurry bin 2, and the cover plate 6 covers the central opening 26 on the top surface of the slurry bin 2; an external thread can be set on the central opening 26 on the top surface of the slurry bin 2, and an internal thread can be set on the edge of the cover plate 6, so that the threaded connection between the cover plate 6 and the slurry bin 2 can be realized.

[0067] like Figure 5 As shown, the central through hole 61 of the cover plate 6 is provided with an internal threaded circular hole, and the central through hole 61 is used to connect the concrete slurry delivery pipe; when the concrete sprayability test is carried out, the central through hole 61 of the cover plate 6 is connected to the concrete slurry delivery pipe, and the size of the central through hole 61 of the cover plate 6 is matched with the size of the concrete slurry delivery pipe, and the freshly mixed concrete is injected into the slurry bin 2 through the central through hole 61 of the cover plate 6 and the slurry delivery pipe.

[0068] Four circular holes with internal threads are arranged around the top of the slurry bin 2 as compressed air inlets, which are connected to the pressurized air pipe with threads during injection; the above-mentioned bin 2 is provided with a pressure gauge 22 for monitoring the real-time air pressure; during the test of the present invention, the air pressure range of the bin 2 is 0.3-1.5MPa; there is a circular hole with internal threads at the center of the bottom of the slurry bin for connecting the injection pipe adapter; in order to avoid the concrete slurry remaining at the bottom of the slurry bin when it flows out, the surface of the bottom 24 of the slurry bin is similar to an inverted cone structure, and the angle between the bottom and the horizontal plane is 3-5 degrees; after the compressed air is added, since the flow rate of the concrete requires continuous flow of the concrete, in order to ensure sufficient supply of the slurry, two transparent observation holes are arranged at the bottom of the slurry bin to facilitate timely judgment of the amount of concrete slurry in the slurry bin.

[0069] The concrete spraying performance is not only related to the rheological properties of concrete, but also to the spraying process. The method for testing the concrete spraying performance is implemented by using the concrete spraying performance test device. The present invention uses the rheological property factor K1 and the spraying process factor K2 to respectively represent the influence of the rheological properties of the sprayed concrete and the process parameters on the spraying performance.

[0070] The method for conducting a concrete spraying performance test using the concrete spraying performance test device comprises the following steps:

[0071] S1: completely lower the partition bin 27 in the slurry bin 2 so that the bottom surface of the partition bin 27 contacts the bottom surface of the slurry bin 2;

[0072] When measuring the rheological properties of concrete, the partition bin 27 in the slurry bin 2 needs to be completely lowered by the robotic arm, the bottom end of the partition bin 27 contacts the inner bottom surface of the slurry bin 2, and the bottom end of the partition bin 27 is located outside the through hole 25 at the bottom end of the slurry bin 2. The cylindrical slurry bin 2 is divided into two parts by the cylindrical partition bin 27, namely, a part located inside the cylindrical partition bin 27 and a part located outside the cylindrical partition bin 27; when measuring the rheological properties of concrete, the partition bin 27 in the slurry bin 2 is completely lowered so that the bottom surface of the partition bin 27 contacts the slurry bin 2, and the through hole 25 at the bottom end of the slurry bin 2 is surrounded by the bottom end of the partition bin 27.

[0073] S2: Close the injection pipe adapter valve 32.

[0074] S3: injecting a fixed volume of fresh concrete into the compartment 27 through the opening at the top of the compartment 27;

[0075] After the injection pipe adapter valve 32 is closed, the pre-prepared quantitative volume of freshly mixed concrete is injected into the partition chamber 27 through the opening at the top of the partition chamber 27; in order to prevent the concrete in the partition chamber 27 from flowing out into the slurry chamber 2, a rubber ring can be provided at the bottom of the partition chamber 27. When the bottom surface of the partition chamber 27 contacts the bottom surface of the inside of the slurry chamber 2, the rubber ring can provide a better sealing effect between the partition chamber 27 and the slurry chamber 2.

[0076] S4: Insert the lower end of the viscometer 1 into the compartment 27 so that the lower end of the viscometer 1 contacts the concrete in the compartment 27, and measure the rheological properties by the viscometer 1. At this time, the critical peak torque T of the concrete paste can be measured by the viscometer 1. C ;

[0077] The lower end of the rotor of the viscometer 1 is extended into the compartment 27, so that the rotor 14 contacts the concrete in the compartment 27, and the rheological properties are measured by the viscometer 1. At this time, the critical peak torque T of the concrete paste can be measured by the viscometer 1. C ;

[0078] The viscometer 1 is received by the opening at the top of the partition chamber 27. Regarding the fixation of the viscometer 1 and the partition chamber 27, threads can be provided on the opening of the partition chamber 27 and the upper side of the viscometer 1, and the two are threadedly connected;

[0079] The partition 27 is provided to take into account the boundary effect. If the partition 27 is not provided, since the area of ​​the slurry bin 2 is larger, when the same volume of concrete is placed in the partition 27 and placed in the slurry bin 2, the lower rotor of the rotational viscometer will encounter less resistance when rotating in the concrete when placed in the slurry bin 2, which may cause inaccurate results measured by the rotational viscometer.

[0080] In step S4, the static yield stress, plastic viscosity, and critical peak torque T of the slurry can be read from the digital display controller 11 through the test of the viscometer 1. C Specific values ​​of other parameters.

[0081] S5: Take out the viscometer 1, stir the concrete slurry in the separation chamber 27, open the injection pipe adapter valve 32, and the concrete in the slurry chamber 2 flows out from the injection pipe 4, and record the time required for the concrete to flow out completely;

[0082] To avoid concrete sticking, after taking out the viscometer 1, manually stir the slurry for 15-30 seconds to restore the viscosity of the concrete, and then open the injection pipe adapter valve 32 to allow the concrete to flow out of the injection pipe 4;

[0083] The time when the concrete flows out completely can be recorded manually with a stopwatch, recording the time from when the concrete flows out from the injection pipe adapter valve 32 when it is opened to when no concrete flows out from the injection pipe. Whether the concrete flows out completely can be judged on the one hand by whether no concrete flows out from the injection pipe, and on the other hand by observing whether there is any remaining concrete in the slurry bin 2 through the transparent observation hole 23. After the concrete flows out completely and no concrete flows out, the concrete injection effect can be measured.

[0084] S6: Take the partition bin 27 out of the slurry bin 2, close the injection pipe adapter valve 32 again, cover the open port of the partition bin 27 with the cover plate 6, inject compressed air into the slurry bin 2 from the multiple air pressure pipe interfaces 21, and inject fresh concrete into the slurry bin 2 from the central through hole 61 of the cover plate 6, and wait until the pressure in the slurry bin 2 reaches the set value; open the injection pipe adapter valve 32 to allow the concrete in the slurry bin 2 to flow out from the injection pipe 4, and record the slurry flow rate through the flow meter 41 on the injection pipe 4;

[0085] When measuring the spraying effect, the partition chamber 27 needs to be taken out. Regarding the removal of the partition chamber 27, the mechanical arm can grab the portion of the partition chamber 27 protruding from the top surface of the slurry bin 2 and take the partition chamber 27 out of the slurry bin 2;

[0086] When measuring the spraying effect, the flow rate of concrete in a specific air pressure range should be measured. Therefore, in step S6, compressed air is injected into the slurry bin 2 from multiple air pressure pipe interfaces 21 to record the flow rate of concrete in a specific air pressure range. The industry generally measures the flow rate of concrete in an air pressure range of 0.3-1.5MPa. The air pressure value in the slurry bin 2 can be observed by a pressure gauge 22.

[0087] In step S6, a cover plate 6 is set, and freshly mixed concrete is injected into the slurry bin 2 from the central through hole 61 of the cover plate 6, and concrete is not directly injected into the slurry bin 2 from the central opening 26 on the top surface of the slurry bin 2. The reason is that the central opening 26 on the top surface of the slurry bin 2 is adapted to the partition bin 27, and the size of the opening 26 is relatively large, and the size of the opening 26 is not adapted to the size of the concrete slurry delivery pipe. Therefore, the cover plate 6 is set, and the central through hole 61 of the cover plate 6 is adapted to the size of the concrete slurry delivery pipe.

[0088] S7: Calculation of static yield stress τ of concrete s , rheological characteristic factor K1 and injection process factor K2,

[0089] Static yield stress of concrete τ s The calculation formula is as follows:

[0090]

[0091] Where: τ s- static yield stress of concrete;

[0092] T C —Slurry critical peak torque;

[0093] h—height of slurry bin;

[0094] R—Viscometer rotor radius;

[0095] The critical peak torque of the slurry is T C By rotating the viscometer, the slurry bin height h and the viscometer rotor radius R are taken according to the actual values; π is taken as 3.14.

[0096] According to the control theory of concrete rheological properties, the unity of material "pumpability" and "sprayability" requires that the plastic viscosity of freshly mixed sprayed concrete is small, but the static yield stress is large, and it can be continuously pumped without blocking the pipe under the shear action of pumping, and can adhere to the base surface without collapse after spraying; the spraying process factor is related to the spraying pressure, the inner diameter of the spraying pipe, the length of the spraying pipe, the slurry flow rate of the spraying pipe, etc. The calculation formulas of the rheological characteristic factor K1 and the spraying process factor K2 are as follows:

[0097]

[0098]

[0099] In formula (2) and formula (3):

[0100] τ s - static yield stress of concrete;

[0101] t—time for slurry to flow out completely;

[0102] v—slurry flow rate in the injection pipe;

[0103] P—air pressure, take the value on the pressure gauge;

[0104] d—inner diameter of the injection pipe, take the actual value;

[0105] l—Injection pipe length, take the actual value;

[0106] S8: judging whether the rheological characteristic factor K1 and the injection process factor K2 are within a preset range. If K1 and K2 are within the preset range, the fresh concrete meets the engineering application requirements; if K1 and K2 are not within the preset range, the fresh concrete does not meet the engineering application requirements;

[0107] The larger the value of the rheological characteristic factor, the better the spraying performance of the material. In order to ensure that the slurry can be sprayed, the rheological characteristic factor K1 should be greater than 10; the spraying process factor K2 needs to be between 0.0015-0.0052 to achieve the best spraying effect of concrete. When the spraying process factor K2 is small, the slurry spraying pressure is insufficient, resulting in low density of the spraying layer, affecting the strength of the material. A large value may cause a high rebound rate of the sprayed concrete. The concrete rebound rate refers to the ratio between the amount of concrete dropped during spraying and the total amount of spraying. The larger the rebound rate, the more wasteful it is, resulting in waste of raw materials and reduced construction efficiency. In the present invention, the range of the spraying process factor K2 is determined by the rebound rate generated during the spraying process under different spraying process parameters.

[0108] If the calculated K1 or K2 is within the preset range, the concrete has good "pumpability" and "sprayability", and the fresh concrete meets the engineering application requirements and can be put into engineering application; if the calculated K1 or K2 is not within the preset range, the fresh concrete does not meet the engineering application requirements;

[0109] If the calculated K1 is not within the pre-set range, viscosity increasing or viscosity reducing materials should be added to the concrete;

[0110] If the calculated K2 is not within the preset range, since the injection process factor K2 is related to the injection pressure, the inner diameter and length of the injection pipe, the injection pressure, the inner diameter or length of the injection pipe can be adjusted to make the injection process factor K2 within the predetermined range, so that the fresh concrete meets the application requirements of the project.

[0111] Table 1 Specific implementation details

[0112]

[0113] In the above table, the control group is the index measured by the rotational viscometer; Example 1 and Example 2 are the results measured by the present device. On the one hand, the present invention only needs to use the rotational viscometer to measure the static yield stress of the material, which reduces the use requirements of the rotational viscometer, and the determination of the static outflow time is extremely convenient. The rheological characteristic factor can be determined based on the above two parameters and the formula (2) of the present invention; at the same time, after the rheological performance measurement is completed, the injection pressure, the inner diameter of the injection pipe, the injection pipe length and other parameters are adjusted to measure the injection slurry flow rate and rebound rate. The injection process factor can be determined based on the above injection process parameters and results, which can provide guidance for the formulation of the actual injection construction process; at the same time, the corresponding relationship between the injection process factor and the rebound rate can be established. Based on the above rheological characteristic factors and injection process factors, a comprehensive test of the injection performance of shotcrete can be achieved.

[0114] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right", etc. indicate an orientation or position relationship based on the orientation or position relationship shown in the drawings, it is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

Claims

1. A shotcrete spraying performance test device, characterized in that: The invention comprises a viscometer (1) and a slurry bin (2), wherein a partition bin (27) is partially located in the slurry bin (2) and can move up and down in the slurry bin (2); the lower end of the viscometer (1) can extend into the partition bin (27), and the viscometer (1) and the partition bin (27) are movably connected; a plurality of air pressure pipe interfaces (21) are arranged on the slurry bin (2), one end of an injection pipe adapter (3) is connected to the bottom surface of the slurry bin (2), and the other end is connected to the injection pipe (4); a plurality of brackets (5) are connected to the slurry bin (2) for supporting the slurry bin (2); when the partition bin (27) is removed from the slurry bin (2), the cover plate (6) can be movably installed on the slurry bin (2); A pressure gauge (22) is fixed on the slurry bin (2), and the pressure gauge (22) is used to monitor the air pressure value in the slurry bin (2); A flow meter (41) is fixed on the injection pipe (4), and the flow meter (41) is used to measure the flow rate of concrete slurry.

2. The spraying performance test device for shotcrete as claimed in claim 1, characterized in that: The middle of the upper surface of the slurry bin (2) is an opening (26), and the opening (26) is adapted to the partition bin (27). The partition bin (27) can move up and down along the opening (26), and the top end of the partition bin (27) protrudes from the upper surface of the slurry bin (2).

3. The spraying performance test device for shotcrete as claimed in claim 1, characterized in that: The top of the partition chamber (27) is open, and the open mouth is used to inject concrete into the partition chamber (27); the top open mouth of the partition chamber (27) and the upper side surface of the viscometer (1) are both provided with threads, and the partition chamber (27) and the viscometer (1) are threadedly connected.

4. The spraying performance test device for shotcrete as claimed in claim 1, characterized in that: A plurality of transparent observation holes (23) are arranged at the lower end of the side wall of the slurry bin (2), and the plurality of transparent observation holes (23) are symmetrically arranged on the side wall of the slurry bin (2).

5. The spraying performance test device for shotcrete as claimed in claim 1, characterized in that: A through hole (25) is provided at the bottom of the slurry bin (2); the through hole (25) is connected to one end of the injection pipe adapter (3), and the other end of the injection pipe adapter (3) is connected to the injection pipe (4); an injection pipe adapter valve (32) is provided at one end of the injection pipe adapter (3) close to the slurry bin (2).

6. The spraying performance test device for shotcrete as claimed in claim 1, characterized in that: The plurality of air compression pipe interfaces (21) are evenly spaced apart on the upper surface of the slurry bin (2) near the edge of the upper surface of the slurry bin (2).

7. The spraying performance test device for shotcrete as claimed in claim 1, characterized in that: When the partition bin (27) is not placed in the slurry bin (2), the cover plate (6) is connected to the slurry bin (2), and the cover plate (6) covers the central opening (26) on the top surface of the slurry bin (2); an external thread is provided on the central opening (26) on the top surface of the slurry bin (2), and an internal thread is provided on the edge of the cover plate (6), and the cover plate (6) is threadedly connected to the slurry bin (2).

8. A method for conducting a concrete spraying performance test using the concrete spraying performance test device according to any one of claims 1 to 7, comprising the following steps: S1: completely lowering the partition bin (27) in the slurry bin (2) so that the bottom surface of the partition bin (27) contacts the bottom surface of the slurry bin (2); S2: Close the injection pipe adapter valve (32); S3: injecting a fixed volume of concrete into the partition chamber (27) through the opening at the top of the partition chamber (27); S4: Extend the lower end of the viscometer (1) into the partition chamber (27) so that the lower end of the viscometer (1) contacts the concrete in the partition chamber (27), and measure the rheological properties by the viscometer (1). At this time, the critical peak torque T of the concrete paste can be measured by the viscometer (1). C ; S5: Take out the viscometer (1), stir the concrete slurry in the separation chamber (27), open the injection pipe adapter valve (32), and the concrete in the slurry chamber (2) flows out from the injection pipe (4), and record the time required for the concrete to flow out completely; S6: Take the partition bin (27) out of the slurry bin (2), close the injection pipe adapter valve (32) again, cover the open opening of the partition bin (27) with the cover plate (6), inject compressed air into the slurry bin (2) from the multiple air pressure pipe interfaces (21), and inject fresh concrete into the slurry bin (2) from the central through hole (61) of the cover plate (6), and wait until the pressure in the slurry bin (2) reaches the set value; open the injection pipe adapter valve (32) to allow the concrete in the slurry bin (2) to flow out from the injection pipe (4), and record the slurry flow rate through the flow meter (41) on the injection pipe (4); S7: Calculation of static yield stress τ of concrete s , rheological characteristic factor K1 and the injection process factor K2; S8: Determine whether the rheological characteristic factor K1 and the injection process factor K2 are within a preset range. If K1 and K2 are within the preset range, the freshly mixed concrete meets the engineering application requirements; if K1 and K2 are not within the preset range, the freshly mixed concrete does not meet the engineering application requirements.

9. The method for testing the performance of concrete spraying as claimed in claim 8, characterized in that: In the step S7, the static yield stress of concrete is s The calculation formula is as follows: Where: τ s - static yield stress of concrete; TC —Slurry critical peak torque; h—height of slurry bin; R—Viscometer rotor radius; The calculation formulas for rheological characteristic factor K1 and injection process factor K2 are as follows: In formula (2) and formula (3): τ s - static yield stress of concrete; t—time for slurry to flow out completely; v—slurry flow rate in the injection pipe; P—air pressure; d—inner diameter of the injection pipe; l—Injection pipe length.

10. The method for testing the performance of concrete spraying according to claim 9, characterized in that: In the step S7, if the calculated K1 is not within the preset range, viscosity-increasing or viscosity-reducing materials are added to the concrete; if the calculated K2 is not within the preset range, the injection pressure, the inner diameter or the length of the injection pipe are adjusted so that the injection process factor K2 is within the preset range.

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