Fresh concrete pumpability testing device, testing method and evaluation method

Abstract

The invention discloses a fresh concrete pumpability testing device, a testing method and an evaluation method, and belongs to the technical field of concrete performance testing. A fresh concrete pumpability testing device comprises a base, the base is provided with a sliding pipe, the periphery of the sliding pipe is communicated with a pair of auxiliary pipes, the pair of auxiliary pipes are respectively provided with a return pipe, the return pipe is provided with a first closing piece, and the peripheries of the pair of auxiliary pipes are respectively provided with a flow velocity detection piece; through the unique structural design, the pumping environment and the pumping behavior of concrete in the pump pipe can be truly simulated, the flowing path of the concrete can be flexibly controlled through the communicating arrangement of the sliding pipe and the auxiliary pipe in cooperation with the backflow pipe and the first closing piece, the movement state of the concrete in the device is closer to the actual pumping scene, and the concrete pumping efficiency is improved. A foundation is laid for accurately detecting the concrete pumpability, meanwhile, two sections of pumpability classification based on the test method are provided for the design of the evaluation method, and the concrete pumpability can be accurately reflected.

Description

Technical Field

[0001] This invention belongs to the field of concrete performance testing technology, and in particular relates to a pumpability testing device, testing method and evaluation method for fresh concrete. Background Technology

[0002] Concrete pumping is an important and efficient construction method in modern civil engineering. When fresh concrete is transported in a pump pipe, a lubricating layer forms near the pipe wall. This lubricating layer is a key factor affecting the pumpability of concrete. Studies by Secrieru et al. have shown that if a lubricating layer fails to form at the interface between the concrete and the pipe wall, the concrete cannot be pumped. A lubricating layer of appropriate thickness and in a stable state can effectively reduce frictional resistance, thereby significantly improving the pumpability of fresh concrete. Therefore, the characteristics of the lubricating layer directly determine the efficiency of concrete pumping.

[0003] Currently, slump and spread are commonly used as indicators to characterize the pumpability of fresh concrete. However, these two indicators can only indirectly reflect the yield stress of concrete and cannot comprehensively and directly characterize its pumpability. Although rheometers and tribometers can be used to measure the rheological parameters of concrete, their portability is insufficient, making it difficult to meet the needs of rapid measurement on construction sites.

[0004] Kasten developed a slide pipe tester based on the Kaplan model, which is currently the most advanced device for evaluating concrete pumpability. However, the operation of the slide pipe tester is relatively complex. Patent CN109085326A provides a pressure slide pipe tester for testing concrete pumpability, but its operation is also complex. Furthermore, in actual pumping processes, the pistons of commonly used engineering pumps need to operate alternately, causing the concrete to intermittently experience peak pump pressures. The designs of existing slide pipe testers and the CN109085326A device do not fully consider the actual pumping environment of concrete. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a pumpability testing device, testing method, and evaluation method for freshly mixed concrete.

[0006] To achieve the above objectives, the invention employs the following technical solution: a pumpability testing device for fresh concrete, comprising a base, a sliding tube on the base, a pair of secondary tubes connected to the outer periphery of the sliding tube, a return pipe connected to the sliding tube on each of the pair of secondary tubes, a first closure element on each of the return pipes, flow velocity detection elements installed on the outer periphery of each of the pair of secondary tubes, pressure sensors installed on the ends of each pair of secondary tubes near the return pipes, a partition and a force transmission plate inside the sliding tube, a pair of spring elements between the force transmission plate and the base, an electric push rod on the base, a mounting base at the output end of the electric push rod, a magnetic attraction element between the mounting base and the force transmission plate, a pressure film sensor on the upper surface of the force transmission plate, and a second closure element between the partition and the sliding tube.

[0007] By adopting the above technical solution, the pumpability testing device for fresh concrete has a reasonable structure. Through the ingenious combination of components such as the base, slide pipe, secondary pipe, and return pipe, a complete testing system is constructed. The setting of baffles and force transmission plates inside the slide pipe, together with spring components, electric push rods, and magnetic suction components, can effectively simulate the concrete pumping process. The installation of flow velocity detection components and pressure sensors on the secondary pipe can obtain key parameters of concrete flow in real time, providing a hardware foundation for accurately evaluating the pumpability of concrete.

[0008] Optionally, the first closure includes a first motor mounted on the outer periphery of the return pipe, and a valve plate located inside the return pipe is mounted on the output end of the first motor.

[0009] By adopting the above technical solution, the first closing element adopts the structure of the valve plate driven by the first motor, which can control the opening and closing of the return pipe. During the test, the return pipe can be flexibly opened or closed according to the needs of different test stages, ensuring that the concrete flows in the sliding pipe and the secondary pipe according to the predetermined process, avoiding the interference of concrete backflow with the test results, and improving the accuracy and stability of the test. At the same time, its pressure sensor, with the cooperation of the first closing element, can obtain the data of the concrete under stable conditions.

[0010] Optionally, the flow rate detection component includes a rubber sleeve and a piezoelectric thin film sensor mounted on the rubber sleeve. The piezoelectric thin film sensor is attached to the secondary tube. The piezoelectric thin film sensors are distributed at 10mm-15mm intervals along the circumference of the rubber sleeve. The piezoelectric thin film sensor is divided into two layers, with a spacing of 310mm-330mm between the upper and lower layers.

[0011] By adopting the above technical solution, the piezoelectric thin film sensor layout on the rubber sleeve of the flow velocity detection component can comprehensively and accurately detect the flow velocity of concrete at different positions and heights in the secondary pipe. It can obtain the flow velocity distribution of concrete in the pipe, provide detailed data for in-depth analysis of the flow characteristics of concrete, and help to more accurately assess the pumpability of concrete.

[0012] Optionally, the spring component includes an outer tube connected to the base, a connecting rod connected to the force transmission plate is provided inside the outer tube, a fixed seat is installed at one end of the connecting rod located inside the outer tube, and a return spring is provided between the fixed seat and the inner bottom wall of the outer tube.

[0013] By adopting the above technical solution, the outer tube, connecting rod, fixed seat and return spring structure of the spring component can provide stable elastic force. During the concrete pumping process of the force transmission plate, the spring component can simulate the elastic effect in actual pumping, making the movement of the force transmission plate more in line with the real situation.

[0014] Optionally, the magnetic attractor includes an electromagnet mounted on the upper surface of the mounting base, and an iron sheet that cooperates with the electromagnet is mounted on the lower surface of the force transmission plate.

[0015] By adopting the above technical solution, the magnetic chuck achieves quick and reliable connection and separation between the mounting base and the force transmission plate through the cooperation of the electromagnet and the iron plate. When the electric push rod pulls the mounting base, the magnetic chuck can ensure that the mounting base and the force transmission plate move synchronously. During testing, the force transmission plate can be easily released.

[0016] Optionally, the second closure includes a second motor mounted on the outer periphery of the slide tube, the output end of the second motor being mounted with a rotating shaft connected to the inner wall of the slide tube, and a closing plate being provided on the outer periphery of the rotating shaft.

[0017] By adopting the above technical solution, before testing, the closing plate can be opened to allow concrete to be poured into the sliding pipe. During the testing phase, closing the closing plate allows concrete to enter the secondary pipe, ensuring the smooth progress of the testing process and improving the standardization and accuracy of the test.

[0018] Optionally, the base is equipped with a data acquisition device, which is electrically connected to the flow rate detection device, the pressure sensor and the pressure diaphragm sensor, respectively. A control panel electrically connected to the data acquisition device is embedded on the surface of the base.

[0019] By adopting the above technical solution, the data acquisition unit inside the base is electrically connected to the flow rate detection device, pressure sensor and pressure diaphragm sensor, which can automatically and in real time collect various data during the test process, and perform preliminary processing and storage. The control panel is electrically connected to the data acquisition unit, and the operator can conveniently set test parameters, start and stop the test through the control panel to realize human-computer interaction and improve the automation level and ease of operation of the test.

[0020] Optionally, a test method for a fresh concrete pumpability testing device includes the following steps:

[0021] Concrete is added into the slide tube, and the force transmission plate stores force and pumps the concrete through the magnetic suction element, the spring element and the electric push rod.

[0022] When concrete is delivered to the secondary pipe, the piezoelectric thin-film sensors on the upper and lower layers of the outer periphery of the secondary pipe respectively measure the upper layer flow velocity value v of the concrete. a and the flow velocity value v of the lower layer of concrete b The pressure sensor measures the bottom pressure value P of the concrete in the secondary pipe when it is in a stable state. b ;

[0023] The data acquisition instrument receives the upper layer flow velocity value v of the concrete. a and the lower layer flow velocity value v of the concrete b The average flow rate Q of the concrete in the secondary pipe is calculated, and the data acquisition instrument receives the pressure value P at the bottom of the concrete. b And calculate the average friction value P of the secondary pipe wall. H ;

[0024] Through multiple tests, the data acquisition instrument obtained multiple sets of average flow rate values ​​Q and average friction values ​​P of the concrete. H and the bottom pressure value P of the concrete b The average value of the values ​​is obtained by linear fitting to obtain the intercept value M and the slope value S of the secondary pipe. The pumpability value K of the concrete is then calculated using the intercept value M and the slope value S of the secondary pipe.

[0025] By adopting the above technical solution, this test method comprehensively considers multiple key parameters of concrete flow. Through multiple tests and data analysis, it can effectively reduce errors, accurately assess the pumpability of concrete, and provide a reliable basis for concrete engineering applications.

[0026] Optionally, the average flow rate of the concrete The average friction value P of the secondary pipe wall H The calculation methods for the intercept value M of the secondary pipe, the slope value S of the secondary pipe, and the pumpability value K of the concrete are as follows:

[0027] ,

[0028] In the formula, The average flow velocity of the concrete is i = 1 or 2, and D is the diameter of the secondary pipe.

[0029] ,

[0030] ,

[0031] In the formula, The average friction value of secondary pipe i, where i = 1 or 2, A i The bottom cross-sectional area of ​​secondary pipe i, The bottom pressure value of secondary pipe i, t i The duration of concrete flow through the velocity detection device on secondary pipe i, The upper flow velocity value of the concrete in the i-th auxiliary pipe, Let g be the lower layer flow velocity of the concrete in the i-th secondary pipe, and g be the gravitational acceleration of the concrete.

[0032] ,

[0033] ,

[0034] In the formula, The concrete pressure value P b The average value, P H The average friction value of the secondary pipe wall, For statistical values, This represents the average flow rate of the concrete.

[0035] ,

[0036] In the formula, L is the length of the secondary pipe, R is the radius of the secondary pipe, γ is the plastic viscosity correction coefficient, with a value range of 1.1~1.15, S is the slope value of the secondary pipe, and M is the intercept value of the secondary pipe.

[0037] By adopting the above technical solutions and using these calculation methods, Q and P are obtained. H The K value can provide an important reference for concrete pumping construction in actual engineering, and also provide accurate data for judging pumpability.

[0038] Optionally, an evaluation method for a test device for the pumpability of fresh concrete includes the following steps:

[0039] After the concrete is added, the pressure diaphragm sensor records the initial weight W1 of the concrete. After the concrete is returned through the return pipe, the pressure diaphragm sensor records the residual weight W2 of the concrete.

[0040] If the difference between the initial weight W1 and the residual weight W2 of the concrete is within the preset weight range, the experiment is deemed valid.

[0041] If the difference between the initial weight W1 and the residual weight W2 of the concrete is outside the preset weight range, the experiment is deemed invalid.

[0042] After the experiment proved effective, the pumpability value K of the concrete was judged by the range of the pumpability value K of the concrete, and the preset range of the pumpability value K was 0~1.

[0043] The closer the pumpability value K of concrete is to 1, the worse the pumpability of the concrete.

[0044] When the pumpability value K of concrete is closer to 0, it indicates that the concrete has better pumpability.

[0045] When 0 < pumpability value K < 0.45, the concrete is in the range of good pumpability.

[0046] By adopting the above technical solution, it is possible to effectively eliminate data deviations caused by unexpected factors such as concrete leakage, severe concrete adhesion to the walls, equipment malfunction, or operational errors during the experiment. At the same time, it also clarifies that the concrete is within the range of good pumpability, providing engineers with a clear standard for quickly selecting high-performance concrete in actual construction.

[0047] Compared with the prior art, the beneficial effects of the present invention are:

[0048] 1. Through its unique structural design, this device can realistically simulate the pumping environment and behavior of concrete in the pump pipe. The connection between the slide pipe and the auxiliary pipe, together with the return pipe and the first closing element, can flexibly control the flow path of the concrete, making the movement state of the concrete in the device closer to the actual pumping scenario, thus laying the foundation for accurately detecting the pumpability of concrete.

[0049] 2. The device adopts a diversion design. After the concrete moves upward in the sliding pipe under the action of the force transmission plate, it flows naturally into a pair of secondary pipes through the control of the baffle and the second closing element. This design increases the number of parallel detection groups, which can simultaneously monitor and process various motion data of the falling concrete. At the same time, the flow velocity detection device and pressure sensor installed on the secondary pipe can comprehensively obtain the flow velocity and pressure information of the concrete at different positions, effectively reducing the error of the detection results and improving the accuracy of concrete pumpability detection.

[0050] 3. A pair of spring components are installed between the force transmission plate and the base. With the cooperation of the electric push rod and the magnetic component, a convenient force transmission system can be constructed. This system can meet different elastic force requirements during the concrete pumpability test by extending and retracting the electric push rod. This allows for the rapid acquisition of test data for different test requirements, and the testing efficiency is significantly improved compared to the traditional sliding tube tester.

[0051] 4. The test method takes into account the potential flow velocity non-uniformity of concrete in the pipeline, more realistically reflecting the actual flow state of concrete. The measurement of pressure values ​​helps to understand the resistance encountered by concrete during pumping, providing rich data support for accurate assessment of pumpability. The intuitive judgment criteria of this evaluation method can provide engineering technicians with a fast and accurate basis for decision-making, helping them to adjust the construction plan in a timely manner and ensure the smooth progress of concrete pumping construction. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the overall structure of the testing device of the present invention;

[0053] Figure 2 This is a schematic diagram of the cross-sectional structure of the testing device of the present invention;

[0054] Figure 3 This is a schematic diagram of the cross-sectional structure of the spring component of the present invention;

[0055] Figure 4 This is a schematic diagram of the three-dimensional connection structure between the mounting base and the electromagnet of the present invention;

[0056] Figure 5 This is a schematic diagram of the three-dimensional connection structure between the force transmission plate and the iron sheet of the present invention;

[0057] Figure 6 This is a top view of the cross-sectional structure of the second closure element of the present invention.

[0058] In the diagram: 1. Base; 11. Cover plate; 2. Slide tube; 3. Secondary tube; 4. Return tube; 5. First closing element; 51. First motor; 52. Valve plate; 6. Flow rate detection element; 61. Rubber sleeve; 62. Piezoelectric film sensor; 7. Spring element; 71. Outer tube; 72. Connecting rod; 73. Fixing seat; 74. Return spring; 8. Magnetic element; 81. Electromagnet; 82. Iron sheet; 9. Second closing element; 91. Second motor; 92. Rotating shaft; 93. Closing plate; 10. Pressure sensor; 11. Partition plate; 12. Force transmission plate; 13. Electric push rod; 14. Mounting seat; 15. Pressure film sensor; 16. Data acquisition instrument; 17. Control panel. Detailed Implementation

[0059] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely 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.

[0060] In the description of this invention, it should be noted that the terms "middle", "upper", "lower", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0061] like Figure 1 As shown in Figure 6, the specific scheme of the embodiment is as follows: A pumpability testing device for fresh concrete includes a base 1. The base 1 provides a stable installation platform for other components such as the slide tube 2, electric push rod 13, and data acquisition instrument 16, ensuring that the device remains stable during the test, reducing the impact of vibration or shaking on the test results, and ensuring the accuracy and reliability of the test. The base 1 is provided with a slide tube 2. The height of the slide tube 2 is 800mm, the diameter of the slide tube 2 is 130mm, the wall thickness of the slide tube 2 is 3mm, and the slide tube 2 is transparent. The transparent design makes it easy for the experimental personnel to observe the phenomenon of concrete hanging on the wall inside the slide tube 2. The design of the slide tube 2 meets the requirements of the concrete flowing fully inside the tube and simulating the actual pumping height, and also makes it easy for the operator to intuitively observe the flow state of the concrete.

[0062] The outer periphery of the slide pipe 2 is connected to a pair of secondary pipes 3. The secondary pipes 3 are divided into two parts: the upper part is curved and the lower part is vertical. The secondary pipes 3 are used to detect the flow parameters of concrete after diversion. The structural design of the slide pipe 2 is more in line with the flow path characteristics of concrete in the actual pumping pipeline. Each of the pair of secondary pipes 3 is provided with a return pipe 4 connected to the slide pipe 2. The angle between the return pipe 4 and the secondary pipe 3 is 90 degrees. The connection between the slide pipe 2 and the return pipe 4 realizes the return of concrete.

[0063] The return pipe 4 is provided with a first closing member 5. The first closing member 5 includes a first motor 51 installed on the outer periphery of the return pipe 4. The output end of the first motor 51 is equipped with a valve plate 52 located inside the return pipe 4. When the first motor 51 is started, the output shaft of the first motor 51 can drive the valve plate 52 to rotate, thereby opening or closing the return pipe 4. The design of the first closing member 5 can control the timing of concrete backflow, ensure that the test is carried out according to the predetermined process, and avoid concrete backflow at an inappropriate time from interfering with the test results. At the same time, it can be used in conjunction with the pressure sensor 10 to avoid errors in the number of pressure sensor 10 acquisitions.

[0064] A flow velocity detection element 6 is installed on the outer periphery of each of the two secondary pipes 3. The flow velocity detection element 6 includes a rubber sleeve 61 and a piezoelectric thin film sensor 62 mounted on the rubber sleeve 61. The piezoelectric thin film sensor 62 is attached to the secondary pipe 3. The rubber sleeve 61 has a height of 350 mm, a thickness of 2 mm, and a radius of 38 mm. The piezoelectric thin film sensors 62 are distributed at intervals of 10 mm-15 mm along the circumference of the rubber sleeve 61. The piezoelectric thin film sensors 62 are divided into two layers, with a distance of 310 mm-330 mm between the upper and lower layers. The flow velocity detection element 6 is used to monitor the average flow velocity of freshly mixed concrete. The rubber sleeve 61 provides the mounting base for the piezoelectric thin film sensors 62. The double-layer design of the piezoelectric thin film sensors 62, which are distributed along the circumference of the rubber sleeve 61, can comprehensively and accurately detect the concrete flow velocity at different positions and heights within the secondary pipe 3, providing reliable data for calculating parameters such as average flow rate.

[0065] Pressure sensors 10 are installed at one end of each pair of secondary pipes 3 near the return pipe 4. The pressure sensors 10 are used to measure the pressure value of concrete in a stable state in the secondary pipes 3. The obtained pressure data can be used to calculate parameters such as the average friction value of the pipe wall of the secondary pipes 3, providing an important basis for evaluating the pumpability of concrete. The slide pipe 2 is provided with a baffle 11 and a force transmission plate 12. The baffle 11 is located in the middle of the slide pipe 2. The lower end of the baffle 11 is provided with a first buffer pad. The upper end of the baffle 11 is on the same horizontal plane as the upper surface of the slide pipe 2. The baffle 11 divides the interior of the slide pipe 2 and, together with the second closing member 9, controls the flow area of ​​concrete. The first buffer pad can reduce the loss caused by the impact of the force transmission plate 12 and extend the service life of the force transmission plate 12.

[0066] The thickness of the force transmission plate 12 is 2mm-4mm. The inside of the force transmission plate 12 is filled with polyurethane. The polyurethane filling can reduce the system instability caused by the direct impact force generated by the spring, making the concrete more uniformly stressed and the test results more accurate. Under the action of the spring component 7 and the electric push rod 13, the force transmission plate 12 applies an upward thrust to the concrete in the slide tube 2, simulating the power source in the pumping process. The upper end of the slide tube 2 is provided with a cover plate 11. The design of the cover plate 11 can prevent external factors in the test environment (such as the project site) from interfering with the test process, and at the same time prevent safety problems caused by human error. The test provides a relatively closed and safe environment.

[0067] A pair of springs 7 are provided between the force transmission plate 12 and the base 1. The springs 7 provide elastic force to the force transmission plate 12, simulating the elastic effect during the pumping process. The spring stiffness coefficient of a single spring 7 is 900~1000N / m. The spring 7 includes an outer tube 71 connected to the base 1. A connecting rod 72 connected to the force transmission plate 12 is provided inside the outer tube 71. A fixed seat 73 is installed at one end of the connecting rod 72 located inside the outer tube 71. A return spring 74 is provided between the fixed seat 73 and the inner bottom wall of the outer tube 71. The structural design of the outer tube 71, connecting rod 72, fixed seat 73 and return spring 74 ensures the stable output of elastic force and the smooth movement of the force transmission plate 12, which can adapt to the testing requirements of concrete with different performance.

[0068] An electric push rod 13 is provided on the base 1, located in the middle of the base 1. The output end of the electric push rod 13 is provided with a mounting base 14, and the surface of the mounting base 14 is provided with a second buffer pad. A magnetic attraction component 8 is provided between the mounting base 14 and the force transmission plate 12. The magnetic attraction component 8 includes an electromagnet 81 installed on the upper surface of the mounting base 14. An iron sheet 82 that cooperates with the electromagnet 81 is installed on the lower surface of the force transmission plate 12. When the electromagnet 81 is energized, it generates an attraction force that attracts the iron sheet 82. When the electric push rod 13 retracts, the electromagnet 81 pulls the force transmission plate 12 downward. When a pumping experiment is required, the electromagnet 81 can be de-energized, causing it to lose its magnetism. The iron sheet 82, which has lost its magnetism, is then pumped by the force transmission plate 12 under the elastic force of the spring component 7. The elastic force of the spring component 7 can be adjusted by adjusting the retraction length of the electric push rod 13, thereby simulating different pumping requirements.

[0069] The upper surface of the force transmission plate 12 is provided with a pressure film sensor 15, which is used to measure the weight of concrete before and after the experiment. The concrete wall adhesion is determined by analyzing the weight of concrete before and after the experiment.

[0070] A second closing member 9 is provided between the partition 11 and the slide pipe 2. The second closing member 9 includes a second motor 91 installed on the outer periphery of the slide pipe 2. The output end of the second motor 91 is equipped with a rotating shaft 92 connected to the inner wall of the slide pipe 2. A closing plate 93 is provided on the outer periphery of the rotating shaft 92. The closing plate 93 is inclined. When the second motor 91 is started, the rotating shaft 92 drives the closing plate 93 to rotate. When it is necessary to fill the slide pipe 2 with concrete, the closing plate 93 is opened. When it is necessary to conduct a pumping test, the closing plate 93 is closed. When the closing plate 93 is closed, the pumped concrete can be better pumped into the secondary pipe 3.

[0071] The base 1 houses a data acquisition unit 16 with 8-16 sampling data channels and a sampling frequency of 100kHz-20MHz. The data acquisition unit 16 is electrically connected to the flow rate detection element 6, the pressure sensor 10, and the pressure diaphragm sensor 15. The data acquisition unit 16 can acquire data from multiple sensors in real time and accurately, perform preliminary processing and storage, providing data support for subsequent data analysis and pumpability evaluation. A control panel 17, electrically connected to the data acquisition unit 16, is embedded in the surface of the base 1. The control panel 17 is used to set test parameters, control the test process, and display test results. Operators can conveniently operate the device through the control panel 17, achieving human-machine interaction and improving the automation and ease of operation of the test.

[0072] A test method for a test device for the pumpability of freshly mixed concrete, the test method comprising the following steps:

[0073] The electromagnet 81 and the electric push rod 13 are activated by the control panel 17. The electric push rod 13 drives the force transmission plate 12 to retract to the lowest position.

[0074] The second motor 91 is started by the control panel 17. The rotating shaft 92 drives the inclined closed plate 93 to rotate, opening the channel between the slide pipe 2 and the partition 11, and slowly pouring the prepared fresh concrete into the slide pipe 2.

[0075] After the slide pipe 2 is filled with enough concrete, the second motor 91 is started again to make the closing plate 93 rotate and close the channel between the slide pipe 2 and the partition plate 11.

[0076] The first motor 51 is started, which drives the valve plate 52 to open, and the return pipe 4 is opened. By de-energizing the electromagnet 81, it loses its magnetism, and the iron sheet 82 on the lower surface of the force transmission plate 12 loses its magnetic attraction. The force transmission plate 12 moves upward under the elastic force of the spring 7, applying an upward thrust to the concrete in the slide pipe 2. After pumping, the electric push rod 13 and the magnetic component drive the force transmission plate 12 back to the lowest position.

[0077] With the cooperation of the closed plate 93, the pumped concrete enters the secondary pipes 3 on both sides and falls freely. The concrete entering the secondary pipes 3 returns to the force transmission plate 12 through the return pipe 4. The pumping operation is carried out 3-5 times, and the inner wall of the sliding pipe 2 is pre-lubricated.

[0078] After pre-lubrication, the control panel 17 controls the flow rate detection element 6 and pressure sensor 10 to start, close the first closing element 5, and at the same time controls the electric push rod 13 to drive the force transmission plate 12 to retract to the first position and then release it;

[0079] When concrete flows through the upper and lower piezoelectric film sensors 62, the upper and lower piezoelectric film sensors 62 respectively measure the upper flow velocity value v of the concrete. a and the flow velocity value v of the lower layer of concrete b After pumping is complete, pressure sensor 10 measures the bottom pressure value P of the concrete in the secondary pipe 3 when it is in a stable state. b ;

[0080] The data acquisition instrument 16 receives the upper layer flow velocity value v of the concrete in real time. a and the flow velocity value v of the lower layer of concrete b The numerical value of the concrete flow rate Q in the secondary pipe 3 is calculated, and the calculation method for the average concrete flow rate Q is as follows:

[0081] ,

[0082] In the formula, The average flow velocity of concrete ( =(v a +v b () / 2), i=1 or 2, D is the diameter of the secondary pipe;

[0083] The data acquisition instrument 16 simultaneously receives the bottom pressure value P of the concrete. b And calculate the average friction value P of the secondary pipe 3 wall. H The average friction value P of the secondary pipe 3 wall H The calculation method is as follows:

[0084] ,

[0085] ,

[0086] In the formula, The average friction value of secondary pipe i, where i = 1 or 2, A i The bottom cross-sectional area of ​​secondary pipe i, The bottom pressure value of the secondary pipe ti The duration of concrete flow through the velocity detection device on secondary pipe i, The upper flow velocity value of the concrete in the i-th auxiliary pipe, Let g be the lower layer flow velocity of the concrete in the i-th auxiliary pipe, and g be the gravitational acceleration of the concrete.

[0087] After the first pumping test, pumping tests were conducted 2-3 more times. In each pumping test, the electric push rod 13 drove the force transmission plate 12 to retract to a different position and then release it.

[0088] After multiple tests, the data acquisition instrument 16 acquired multiple sets of average flow rate values ​​Q and statistical values ​​P. A linear fitting method was used to obtain the PQ relationship, which is as follows:

[0089] ,

[0090] ,

[0091] In the formula, The pressure value P at the bottom of the concrete b The average value, P H The average friction value of the secondary pipe wall, For statistical values, This represents the average flow rate of the concrete.

[0092] The pumpability value K is calculated using the slope S and intercept M. The calculation method for the pumpability value K is as follows:

[0093] ,

[0094] In the formula, L is the length of the secondary pipe, R is the radius of the secondary pipe, γ is the plastic viscosity correction coefficient, with a value range of 1.1~1.15, S is the slope value of the secondary pipe, and M is the intercept value of the secondary pipe.

[0095] An evaluation method for a test device for the pumpability of freshly mixed concrete, the evaluation method comprising the following steps:

[0096] After the concrete is added, the pressure diaphragm sensor records the initial weight W1 of the concrete. After the concrete is returned through the return pipe, the pressure diaphragm sensor records the residual weight W2 of the concrete.

[0097] If the difference between the initial weight W1 and the residual weight W2 of the concrete is within the preset weight range, the experiment is deemed valid.

[0098] If the difference between the initial weight W1 and the residual weight W2 of the concrete is outside the preset weight range, the experiment is deemed invalid.

[0099] After the experiment proved effective, the pumpability value K of the concrete was judged by the range of the pumpability value K of the concrete, and the preset range of the pumpability value K was 0~1.

[0100] The closer the pumpability value K of concrete is to 1, the worse the pumpability of the concrete.

[0101] When the pumpability value K of concrete is closer to 0, it indicates that the concrete has better pumpability.

[0102] When 0 < pumpability value K < 0.45, the concrete is in the range of good pumpability.

[0103] Example 2: To test the specific application effect of the present invention, four different strength grades of concrete mix proportions were used in the experiment, as shown in Table 1:

[0104]

[0105] The experiment was conducted using the test method described in Implementation 1. In the experiment, the extension length of the electric push rod 13 needed to be adjusted. By setting different extension lengths, the elastic force of the spring 7 was changed, and concrete delivery data under different elastic forces were obtained. The plastic viscosity correction coefficient γ was taken as 1.15. The pumpability value K of the concrete was calculated using the calculation method described in Implementation 1, and the results are shown in Table 2.

[0106]

[0107] As shown in Table 2, the pumpability values ​​K for C30 and C40 are in the range of 0 to 0.45, indicating good pumpability. The pumpability values ​​K for C50 and C60 are slightly higher, both exceeding the limit of 0.45, indicating poor pumpability. The test results are consistent with the inverse relationship between concrete strength and its rheological properties. Increasing the concrete strength requires increasing the total amount of cementitious materials, which directly increases the micro-friction resistance between concrete particles and ultimately deteriorates its pumpability.

[0108] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A device for testing the pumpability of freshly mixed concrete, characterized in that, The device includes a base, a slide tube on the base, a pair of secondary tubes connected to the outer periphery of the slide tube, a return pipe connected to the slide tube on each of the secondary tubes, a first closure on each return pipe, flow velocity detection elements installed on the outer periphery of each of the secondary tubes, pressure sensors installed on the ends of each of the secondary tubes near the return pipes, a partition and a force transmission plate inside the slide tube, a pair of springs between the force transmission plate and the base, an electric push rod on the base, a mounting base at the output end of the electric push rod, a magnetic attraction between the mounting base and the force transmission plate, a pressure film sensor on the upper surface of the force transmission plate, and a second closure between the partition and the slide tube.

2. The pumpability testing device for freshly mixed concrete according to claim 1, characterized in that: The first closure element includes a first motor installed on the outer periphery of the return pipe, and a valve plate located inside the return pipe is installed at the output end of the first motor.

3. The pumpability testing device for freshly mixed concrete according to claim 1, characterized in that: The flow rate detection component includes a rubber sleeve and a piezoelectric thin film sensor mounted on the rubber sleeve. The piezoelectric thin film sensor is attached to the sub-tube. The piezoelectric thin film sensors are distributed at intervals of 10mm-15mm along the circumference of the rubber sleeve. The piezoelectric thin film sensor is divided into two layers, with a distance of 310mm-330mm between the upper and lower piezoelectric thin film sensors.

4. The pumpability testing device for freshly mixed concrete according to claim 1, characterized in that: The spring component includes an outer tube connected to the base, a connecting rod connected to the force transmission plate inside the outer tube, a fixed seat installed at one end of the connecting rod inside the outer tube, and a return spring between the fixed seat and the inner bottom wall of the outer tube.

5. The pumpability testing device for freshly mixed concrete according to claim 1, characterized in that: The magnetic attractor includes an electromagnet mounted on the upper surface of the mounting base, and an iron sheet that cooperates with the electromagnet is mounted on the lower surface of the force transmission plate.

6. The pumpability testing device for freshly mixed concrete according to claim 1, characterized in that: The second closing element includes a second motor installed on the outer periphery of the slide tube, and the output end of the second motor is equipped with a rotating shaft connected to the inner wall of the slide tube. A closing plate is provided on the outer periphery of the rotating shaft.

7. The pumpability testing device for freshly mixed concrete according to claim 1, characterized in that: The base contains a data acquisition device, which is electrically connected to the flow rate detection device, the pressure sensor, and the pressure diaphragm sensor. A control panel electrically connected to the data acquisition device is embedded in the surface of the base.

8. The test method for the pumpability testing device for freshly mixed concrete according to any one of claims 1-7, characterized in that, The testing method includes the following steps: Concrete is added into the slide tube, and the force transmission plate stores force and pumps the concrete through the magnetic suction element, the spring element and the electric push rod. When concrete is delivered to the secondary pipe, the piezoelectric thin-film sensors on the upper and lower layers of the outer periphery of the secondary pipe respectively measure the upper layer flow velocity value v of the concrete. a and the flow velocity value v of the lower layer of concrete b The pressure sensor measures the bottom pressure value P of the concrete in the secondary pipe when it is in a stable state. b ; The data acquisition instrument receives the upper layer flow velocity value v of the concrete. a and the lower layer flow velocity value v of the concrete b The average flow rate Q of the concrete in the secondary pipe is calculated, and the data acquisition instrument receives the bottom pressure P of the concrete. b And calculate the average friction value P of the secondary pipe wall. H ; Through multiple tests, the data acquisition instrument obtained multiple sets of average flow rate values ​​Q and average friction values ​​P of the concrete. H and the bottom pressure value P of the concrete b The average value of the values ​​is obtained by linear fitting to obtain the intercept value M and the slope value S of the secondary pipe. The pumpability value K of the concrete is then calculated using the intercept value M and the slope value S of the secondary pipe.

9. The test method for the pumpability testing device of freshly mixed concrete according to claim 8, characterized in that: The average flow rate of the concrete The average friction value P of the secondary pipe wall H The calculation methods for the intercept value M of the secondary pipe, the slope value S of the secondary pipe, and the pumpability value K of the concrete are as follows: ， In the formula, The average flow velocity of the concrete is i = 1 or 2, and D is the diameter of the secondary pipe. ， ， In the formula, The average friction value of secondary pipe i, where i = 1 or 2, A i The bottom cross-sectional area of ​​secondary pipe i, The bottom pressure value of secondary pipe i, t i The duration of concrete flow through the velocity detection device on secondary pipe i, The upper flow velocity value of the concrete in the i-th auxiliary pipe, Let g be the lower layer flow velocity of the concrete in the i-th secondary pipe, and g be the gravitational acceleration of the concrete. ， ， In the formula, The pressure value P at the bottom of the concrete b The average value, P H The average friction value of the secondary pipe wall, For statistical values, This represents the average flow rate of the concrete. ， In the formula, L is the length of the secondary pipe, R is the radius of the secondary pipe, γ is the plastic viscosity correction coefficient, with a value range of 1.1~1.15, S is the slope value of the secondary pipe, and M is the intercept value of the secondary pipe.

10. The evaluation method for the pumpability testing device of freshly mixed concrete according to claim 8, the evaluation method comprising the following steps: After the concrete is added, the pressure diaphragm sensor records the initial weight W1 of the concrete. After the concrete is returned through the return pipe, the pressure diaphragm sensor records the residual weight W2 of the concrete. If the difference between the initial weight W1 and the residual weight W2 of the concrete is within the preset weight range, the experiment is deemed valid. If the difference between the initial weight W1 and the residual weight W2 of the concrete is outside the preset weight range, the experiment is deemed invalid. After the experiment proved effective, the pumpability value K of the concrete was judged by the range of the pumpability value K of the concrete, and the preset range of the pumpability value K was 0~1. The closer the pumpability value K of concrete is to 1, the worse the pumpability of the concrete. When the pumpability value K of concrete is closer to 0, it indicates that the concrete has better pumpability. When 0 < pumpability value K < 0.45, the concrete is in the range of good pumpability.

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