Concrete working performance evaluation device based on circular ring test, evaluation method and application thereof

Abstract

The invention belongs to the field of concrete, and particularly relates to a concrete working performance evaluation device and evaluation method based on a circular ring test and application thereof. The device comprises a charging container, a vibration table, a weighing device and a timing device, according to the method, by simulating the vibration environment, the test result can more truly reflect the interaction between the concrete and the reinforcing steel bar and between the concrete in the construction process; the cohesiveness and trafficability of the concrete are quantitatively evaluated by simulating the relative movement of the circular ring of the reinforcing steel bar and the concrete and measuring the mass of slurry attached to the circular ring; according to the method, key parameters such as vibration time and laitance thickness in the concrete pouring process can be accurately predicted; the application is the application in predicting the vibration time and laitance thickness in the pouring process of the fresh concrete based on the circular ring sinking time and the circular ring attached slurry mass. According to the method, the operation steps and time are reduced, and the working performance of the concrete can be rapidly and accurately evaluated.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and particularly relates to a device for evaluating the workability of concrete based on ring tests, an evaluation method and its application. Background Art

[0002] During the steam curing process, the concrete of shield segments is prone to shrinkage, which may lead to the generation of cracks. Therefore, during design, a smaller paste volume and a higher proportion of aggregates are required to reduce shrinkage and avoid cracking. At the same time, considering that the mold of the shield segment is an arc structure, the water-binder ratio of the concrete is required to be low, and the slump must also be controlled within a low range (30 mm to 70 mm). If the slump is too high, the concrete will flow to both sides of the mold, resulting in the phenomenon of collapse in the middle; while if the slump is too low, it will lead to an increase in the viscosity of the concrete, poor fluidity, insufficient filling performance, and prone to problems such as voids or surface quality problems.

[0003] The traditional slump test is carried out in a static state. The concrete sample is filled into a slump bucket. After filling the concrete, the slump bucket is quickly lifted vertically upward, allowing the concrete to collapse freely. In actual construction, in order to enhance the toughness of the concrete of the shield segment and prevent cracking, reinforcing materials such as steel fibers and polypropylene fibers are usually added, but this will also lead to a further increase in the viscosity of the concrete. And during the pouring process of the segment concrete, a strong vibration effect must be applied to ensure the compactness of the concrete. The vibration time depends on the experience of the workers, and there may be problems such as insufficient vibration leading to voids, or over-vibration leading to too large a thickness of the floating slurry, affecting the quality of the segment.

[0004] The current traditional slump and Vebe consistency test methods cannot effectively reflect the viscosity and cohesiveness of the concrete, and cannot provide sufficient guidance for the vibration effect and the quality of concrete pouring. Therefore, an improved technical solution for the deficiencies of the above-mentioned existing technologies is needed. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the existing technologies and provide an evaluation method and its application for the workability of shield segment concrete based on ring tests. By simulating the relative movement between the ring of steel bars and the concrete, and measuring the mass of the attached slurry on the ring, the cohesiveness and passability of the concrete are quantitatively evaluated, and key parameters such as the vibration time and the thickness of the floating slurry during the concrete pouring process are predicted, thereby making up for the multi-dimensional workability evaluation that cannot be provided by the traditional method, and is particularly suitable for on-site rapid testing of special types of concrete such as shield segment concrete.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] A device for evaluating the workability of concrete based on ring tests, comprising:

[0008] A loading container, wherein the loading container is used to store fresh concrete;

[0009] A vibration table, on which the loading container is mounted, and the vibration table vibrates the loading container at a stable vibration frequency; the vibration frequency is adjustable;

[0010] A weighing device, the weighing device is used to weigh the mass of the ring and the slurry attached to the ring;

[0011] A timing device is used for timing.

[0012] Further, the vibration table includes a base, a table top mounted on the base through a spring, and a vibration mechanism fixed on the base and connected to the table top;

[0013] The loading container is detachably fixed on the table top by a fixing bracket; the fixing bracket comprises at least two pairs of bracket screws vertically mounted on the table top, each pair of bracket screws is penetrated by a same fixing pressure plate, the fixing pressure plate is pressed against the top of the loading container and fixed by a locking nut threadedly mounted on the bracket screw.

[0014] Furthermore, the concrete working performance evaluation device based on the ring test also includes a ring placing device, which is detachably arranged on a charging container or a table top, and is used to place the ring horizontally on the upper surface of the freshly mixed concrete in the charging container.

[0015] Furthermore, the ring delivery device includes a frame, a plurality of vertical rods rotatably mounted on the frame, and a synchronous rotation mechanism that simultaneously drives the vertical rods to rotate horizontally; the number of the vertical rods is more than 3, and the vertical rods are arranged in a circle; a support plate is horizontally fixed to the bottom of the vertical rod, and the support plate is used to support the ring; the height of the frame or the support plate is adjustable.

[0016] Furthermore, the synchronous rotation mechanism includes a synchronous wheel fixed on the vertical rod, a synchronous belt connected to the synchronous wheel, and a paddle fixed on the synchronous belt; the synchronous wheel is rotatably mounted on the frame plate; a clamp is fixed on the upper surface of the synchronous wheel, and the clamp includes a plurality of anchor petals, one of which is fixed on the upper surface of the synchronous wheel, and all of the anchor petals are clamped on the vertical rod by locking members arranged on their peripheries.

[0017] The present invention also proposes a method for evaluating the working performance of shield segment concrete based on a circular ring test, which uses the aforementioned concrete working performance evaluation device based on a circular ring test to perform evaluation, and includes the following steps:

[0018] S1. Test preparation: Weigh the initial weight of the ring through a weighing device; Fill the fresh concrete in the loading container and make the surface of the fresh concrete flat; Adjust the vibration frequency and amplitude of the vibrating table to the frequency and amplitude to be tested.

[0019] S2. Gently place the ring on the surface of the fresh concrete in the loading container; Start the vibrating table and start timing; Stop timing after the ring is completely immersed in the fresh concrete to obtain the immersion time of the ring.

[0020] S3. Slowly take out the ring from the fresh concrete, weigh it and record it when the slurry attached to the ring no longer drips; Subtract the initial weight of the ring from this weight to obtain the mass of the slurry attached to the ring.

[0021] S4. Evaluate the cohesiveness and passability of the concrete based on the immersion time of the ring and the mass of the slurry attached to the ring.

[0022] Further, the outer diameter of the ring is 100 - 200 mm and the wire diameter is 8 - 12 mm; The surface of the ring is rough or smooth.

[0023] Further, the adjustable range of the vibration frequency of the vibrating table is 0 - 50 Hz, and the amplitude is 0.5 - 2 mm; The time from the completion of mixing of the fresh concrete sample to the start of testing is within 10 minutes; The volume of the fresh concrete is 1 / 2 - 2 / 3 of the capacity of the loading container.

[0024] Further, the ring is placed horizontally on the surface of the fresh concrete; If the ring fails to sink normally within the preset time range, pause the vibration, take out the ring and clean it; Transfer the ring to another position on the surface of the fresh concrete, start the vibrating table and re-time until the ring is smoothly immersed in the fresh concrete.

[0025] The present invention also proposes an application of a method for evaluating the working performance of shield segment concrete based on ring testing, including applications in predicting the vibration time and floating slurry thickness during the pouring process of fresh concrete based on the immersion time of the ring and the mass of the slurry attached to the ring.

[0026] The application process is as follows: during the ring test, the vibration time, slump, Vebe consistency, and floating slurry thickness during the segment casting process of the same freshly mixed concrete are tested according to the conventional method; the mass of the slurry attached to the ring, the immersion time of the ring, and the vibration time during the casting process are fitted to obtain the first relationship between the mass of the slurry attached to the ring and the vibration time during the casting process, and the second relationship between the immersion time of the ring and the vibration time during the casting process; the mass of the slurry attached to the ring and the floating slurry thickness are fitted to obtain the third relationship between the mass of the slurry attached to the ring and the floating slurry thickness; thus, the vibration time during the casting process of the freshly mixed concrete can be predicted based on the mass of the slurry attached to the ring, the immersion time of the ring, the first relationship, and the second relationship obtained from the ring test, and the floating slurry thickness during the casting process of the freshly mixed concrete can be predicted based on the mass of the slurry attached to the ring and the third relationship obtained from the ring test.

[0027] The working principle of the present invention is as follows: by measuring the immersion time of the ring in the concrete at different vibration frequencies, the passability of the concrete can be accurately characterized, that is, the relative movement ability between the concrete and the steel bars, and the key indexes such as the vibration time and floating slurry thickness required during the concrete casting process can be effectively predicted; the mass of the slurry attached to the ring can provide a quantitative evaluation of the cohesiveness of the concrete. In addition, by combining the ring test results with traditional test methods such as slump and Vebe consistency, a more comprehensive and accurate multi-dimensional evaluation of the workability of the concrete can be carried out.

[0028] The beneficial effects of the present invention are as follows:

[0029] The present invention proposes a new method based on the ring test. By simulating the vibration environment, the test results can more realistically reflect the interaction between the concrete and the steel bars and between the concretes during the construction process; by simulating the relative movement between the ring simulating the steel bars and the concrete and measuring the mass of the slurry attached to the ring, the cohesiveness and passability of the concrete are quantitatively evaluated; this method can accurately predict the key parameters such as the vibration time and floating slurry thickness during the concrete casting process, thereby making up for the multi-dimensional workability evaluation that cannot be provided by the traditional method, and is especially suitable for the on-site rapid test of special types of concrete such as shield segment concrete; the new test method provided by the present invention reduces the operation steps and time, and can quickly and accurately evaluate the workability of the concrete;

[0030] The present invention has a wide application range and is applicable not only to low-slump concrete, but also to different types of freshly mixed concrete such as high-strength concrete, ultra-high-performance concrete, and shield segment concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0032] Figure 1 This is a schematic structural diagram of the device for evaluating the workability of concrete based on ring tests according to the present invention.

[0033] Figure 2 This is a schematic structural diagram of another perspective of the device for evaluating the workability of concrete based on ring tests according to the present invention.

[0034] Figure 3 This is a top view of the device for evaluating the workability of concrete based on ring tests according to the present invention.

[0035] Figure 4 This is a schematic structural diagram of the ring placement device of the embodiment of the present invention when supporting the ring.

[0036] Figure 5 This is a schematic structural diagram of the ring placement device of the embodiment of the present invention when releasing the ring.

[0037] Figure 6 This is a relationship diagram between the Vebe consistency and the vibration time during the pouring process in the application example of the present invention.

[0038] Figure 7 This is a relationship diagram between the slump and the vibration time during the pouring process in the application example of the present invention.

[0039] Figure 8 This is a relationship diagram between the mass of the slurry attached to the ring and the vibration time during the pouring process in the application example of the present invention.

[0040] Figure 9 This is a relationship diagram between the immersion time of the ring and the vibration time during the pouring process in the application example of the present invention.

[0041] Figure 10 This is a relationship diagram between the immersion time - vibration frequency sensitivity of the ring and the vibration time during the pouring process in the application example of the invention.

[0042] Figure 11 This is a change diagram of the slump of concrete and the thickness of the floating slurry in the application example of the present invention.

[0043] Figure 12 This is a relationship diagram between the Vebe consistency of concrete and the thickness of the floating slurry in the application example of the present invention.

[0044] Figure 13 This is a relationship diagram between the mass of the slurry attached to the ring and the thickness of the floating slurry in the application example of the present invention.

[0045] In the figure: 101, base; 102, circular pipe section; 103, spring; 104, vibration motor; 105, connecting plate; 106, tabletop; 107, angle piece; 201, frequency regulator; 202, wire; 301, support base plate; 302, support screw; 303, fixed pressing plate; 304, locking nut; 4, loading container; 5, circular ring; 601, rod base; 602, vertical rod; 603, sliding cylinder; 604, cross bar; 605, camera connecting piece; 606, camera; 701, support plate; 702, synchronous belt; 703, inner baffle; 704, outer baffle; 705, dialing port; 706, dialing piece; 707, support board; 708, synchronous pulley; 709, locking piece; 710, anchor petal; 711, vertical rod; 712, supporting plate. Detailed implementation manners

[0046] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0047] In the description of the present invention, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of the present invention. The terms "connected" and "connected" used in the present invention should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate component. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific situations.

[0048] The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0049] The present invention provides a device and method for evaluating the working performance of concrete based on circular ring testing; by designing an experimental process and a supporting evaluation device that can simulate the flow of concrete in the gaps between steel bars, combined with the circular ring testing method for fresh concrete, it is possible to accurately characterize the working performance of concrete and predict the key parameters during its pouring process.

[0050] As Figures 1 to 5 shown, a device for evaluating the working performance of concrete based on circular ring testing includes:

[0051] A charging container 4, which is soluble in storing freshly mixed concrete;

[0052] A vibrating table, on which the charging container 4 is installed, and the vibrating table vibrates the charging container 4 at a stable vibration frequency; the vibration frequency is adjustable;

[0053] A weighing device, which is used to weigh the mass of the ring 5 and the slurry attached to the upper ring thereof;

[0054] A timing device, which is used for timing; the timing device can be a stopwatch or an intelligent monitoring system based on image recognition.

[0055] When conducting the ring test, first pour the freshly mixed segment concrete into the charging container 4 and level it by scraping or vibrating; then gently place the ring 5 on the upper surface of the freshly mixed concrete. At this time, due to the surface tension of the concrete, the ring 5 will not sink immediately and quickly; start the vibrating table and timing. The ring 5 sinks, and stop timing when the ring 5 is completely submerged, then the immersion time of the ring can be obtained.

[0056] When placing the ring 5, it can be placed by hand or a special ring placing device can be used. The ring placing device is detachably arranged on the charging container 4 or the tabletop 106. After the freshly mixed concrete is poured into the charging container 4 and installed on the tabletop 106, the ring placing device is installed. The ring placing device includes a frame plate 701, a plurality of vertical rods 711 rotatably installed on the frame plate 701, and a synchronous rotation mechanism for simultaneously driving the horizontal rotation of the vertical rods 711; an outwardly extending support plate 707 is arranged on the frame plate 701, and the support plate 707 can support on the fixed pressing plate 303 or the peripheral wall of the charging container 4 to support the frame plate 701 above the freshly mixed concrete; outer baffles 704 and inner baffles 703 for limiting the synchronous belt 702 are respectively fixed at positions corresponding to the outer side and the outer side of the synchronous belt 702 on the frame plate 701. The number of the vertical rods 711 is more than 3, and the vertical rods 711 are arranged in a circle; a tray 712 is horizontally fixed at the bottom of the vertical rod 711, and the tray 712 is used to support the ring 5. The synchronous rotation mechanism includes a synchronous pulley 708 fixed on the vertical rod 711, a synchronous belt 702 connecting the synchronous pulley 708, and a paddle 706 fixed on the synchronous belt 702; the synchronous pulley 708 is rotatably installed on the frame plate 701, and a plate hole corresponding to the vertical rod 711 is arranged on the frame plate 701, and the vertical rod 711 is concentrically arranged with the synchronous pulley 708; Figure 4 、 Figure 5The paddle 706 is extended horizontally through the paddle opening 705 provided in the outer baffle 704. In addition, since there is an exposed area on the top surface of the synchronous belt 702, the paddle 706 can also be set on the top surface of the synchronous belt 702 and extend upward. When in use, the vertical rod 711 and the support plate 712 thereon are rotated simultaneously by paddle 706 in clockwise and counterclockwise directions. A clamp is fixed on the upper surface of the synchronous wheel 708, and the clamp is used to clamp the different positions of the vertical rod 711 to adjust the position of the support plate 712; the clamp includes a plurality of anchor flaps 710 and locking members 709, one of which is fixed on the upper surface of the synchronous wheel 708; all the anchor flaps 710 are clamped on the vertical rod 711 by the locking members 709 arranged on their peripheries; in one embodiment, all the anchor flaps 710 can be assembled into a structure with a top similar to a cone, and the middle hole of the locking member 709 is provided with an internal thread, which can be threadedly connected with the anchor flap 710, so that the anchor flap 710 is close to the vertical rod 711; in another embodiment, as in Figure 4 , Figure 5 As shown, the locking member 709 can be a cable tie, iron wire, clamp, etc., and the anchor flap 710 can be made of plastic, rubber, metal, etc. Preferably, in order to ensure that the height of the support plate 712 is consistent and the ring 5 is placed horizontally, an auxiliary frame (the auxiliary frame is not shown in the figure) is used to connect all the vertical rods 711, such as rotating the top of the vertical rod 711 on the auxiliary frame, and on the basis of retaining the self-rotation function of the vertical rod 711, all the vertical rods 711 can only be raised and lowered at the same time.

[0057] When the ring delivery device is in use, the frame 701 is first placed on the fresh concrete according to the installation position, and the height of the support plate 712 is adjusted by the clamp to make it close to the upper surface of the fresh concrete; the support plate 712 is adjusted by the paddle 706 so that all the support plates 712 face the axis of the synchronous belt 702 to achieve Figure 4 Then lift the ring delivery device slightly, place the ring 5 on the support plate 712, and then carefully place the support plate 707 and the frame plate 701 in the installation position; press the frame plate 701 or the support plate 707 with one hand to prevent it from moving, and use the other hand to turn the paddle 706 to rotate the support plate 712 at least 90° to release the ring 5. Figure 5 The middle shows the state of the ring delivery device after release; then the ring delivery device is lifted up and taken away, the vibration table is started, and the timing begins.

[0058] When the timing device is a stopwatch, two people cooperate with one person to release the ring 5, and one person to hold the stopwatch to time. Figures 1 to 3As shown, the intelligent monitoring system includes a monitoring support, a timing system, and a camera 606 disposed above the loading container 4 through the monitoring support. The field of view of the camera 606 completely covers the area of the loading container 4. The camera 606 continuously records the process of the ring 5 from being dropped to being completely submerged in the concrete, and the timing system obtains the time from when the ring 5 is dropped to when it is completely submerged in the concrete, which is used as the ring immersion time. The monitoring support includes a rod base 601, a vertical rod 602 welded and fixed to the rod base 601, a sliding cylinder 603 sleeved on the vertical rod 602, a cross bar 604 welded and fixed to the sliding cylinder 603, and a camera connecting member 605 disposed on the cross bar 604. The camera connecting member 605 can slide along the cross bar 604 and lock its position, and the sliding cylinder 603 can slide along the vertical rod 602 and lock its position, so as to adjust the height and horizontal position of the camera 606. By adjusting the position of the camera 606, it is ensured that the field of view can completely cover the area of the concrete container, and at the same time, the recognition and capture effect of the camera 606 on the ring 5 is optimized. The camera 606 uses an industrial camera 606. Connecting the camera 606 to a computer, the moment when the ring 5 is submerged can be determined by manual frame-by-frame recognition or automatically recognized by software, which improves the time recording accuracy of the device and also enhances the objectivity and data reproducibility of the experiment.

[0059] Further, the maximum frequency of the shaking table is 50 Hz, and the amplitude is 0.5 - 2 mm; as Figures 1 to 3As shown in the figure, the vibrating table includes a base 101, a tabletop 106 mounted on the base 101 through springs 103, and a vibration mechanism fixed on the base 101 and connected to the tabletop 106; the tabletop 106 is horizontally installed; the loading container 4 is detachably fixed on the tabletop 106 through a fixing bracket; the fixing bracket includes at least 2 pairs of bracket screws 302 vertically installed on the tabletop 106, and the same fixing pressure plate 303 is penetrated through each pair of bracket screws 302. The fixing pressure plate 303 presses against the top end of the loading container 4 and is fixed by a locking nut 304 threadedly installed on the bracket screw 302; generally, 2 pairs of bracket screws 302 are set. The bottom of this pair of bracket screws 302 is fixed on the bracket bottom plate 301. The bracket bottom plate 301 is located below the tabletop 106, and the bracket screw 302 passes upward through a rod hole opened on the tabletop 106; by tightening the nut, the fixing pressure plate 303 moves downward to achieve the effect of fixing the loading container 4, and finally realizes the effect that the loading container 4 and the fresh concrete inside vibrate synchronously with the vibrating tabletop 106. The base 101 is a rectangular frame structure welded by H-shaped steel. Angle pieces 107 are welded at the four corners above the base 101. The bottom of the spring 103 is welded and fixed to the angle piece 107; circular pipe sections 102 are respectively welded and fixed at the four corners of the bottom surface of the tabletop 106 and the top surface of the angle piece 107. The circular pipe section 102 is used to limit the displacement of the spring 103 under vibration. The vibration mechanism includes a vibration motor 104 and a connecting plate 105 supporting the vibration motor 104. The connecting plate 105 is installed at the center of the bottom surface of the tabletop 106.

[0060] Further, the vibration motor 104 is equipped with a frequency modulation system. The frequency modulation system includes a frequency regulator 201 for controlling the frequency of the vibration motor 104 and a wire 202 connected to a 220V power supply; the adjustable frequency range of the frequency regulator 201 is 0 - 50Hz.

[0061] As Figures 1 to 6 shown in the figure, the loading container 4 is preferably a circular container; in a specific embodiment, the depth of the loading container 4 is 20 cm and the diameter is 50 cm. The outer diameter of the ring 5 is 100 - 200 mm and the wire diameter is 8 - 12 mm; for example, the ring 5 can be of different specifications such as an outer diameter of 150 mm and a wire diameter of 8 mm, an outer diameter of 150 mm and a wire diameter of 10 mm, an outer diameter of 150 mm and a wire diameter of 12 mm, etc. According to the concrete in different application scenarios, a suitable ring 5 can be selected; in addition to being circular, the shape of the ring 5 can also be a closed shape such as square, triangular, or special-shaped, but it is preferably a centrosymmetric figure. The surface of the ring 5 can be smooth or rough. For example, by polishing, sandblasting or setting depressions, protrusions, etc. to increase the surface roughness and increase the adhesion quality of the ring 5 to reduce errors. The ring 5 used in this embodiment is a ring 5 shape made of solid smooth stainless steel.

[0062] The present invention also provides a method for evaluating the working performance of shield segment concrete based on ring tests, comprising the following steps:

[0063] S1. Test preparation: Weigh the initial weight of the ring through a weighing device; Prepare the concrete, fill the fresh concrete into the loading container 4, and the amount of the fresh concrete is about 2 / 3 of the capacity of the loading container 4. Then, install the loading container 4 filled with the fresh concrete on the vibrating table surface 106 through a fixing bracket, and start the vibrating table to level the fresh concrete;

[0064] Adjust the vibration frequency of the vibrating table to the frequency to be tested and the test amplitude;

[0065] S2. Gently place the ring 5 on the surface of the fresh concrete in the loading container 4; Start the vibrating table and start timing; Stop timing after the ring 5 is completely immersed in the fresh concrete to obtain the ring immersion time;

[0066] S3. Slowly take out the ring 5 from the fresh concrete, weigh and record it when the slurry attached to the ring 5 no longer drips within 10s / 6s / 5s / 3s / 2s; Subtract the initial weight of the ring from this weight to obtain the mass of the slurry attached to the ring;

[0067] S4. Evaluate the cohesiveness and passability of the concrete based on the ring immersion time and the mass of the slurry attached to the ring.

[0068] Note: ① For the fresh concrete sample, the time interval from the completion of mixing to the start of testing should be controlled within 10 minutes. When the state of the mixture is significantly different from the state at the time of discharge from the mixer, a new sample should be prepared. ② If the ring 5 fails to sink normally within a preset time range (for example, within 15s or a shorter time), or if some of the rings 5 sink relatively fast within a short time while the other side does not sink for a long time (for example, more than 3s), it can be judged that the ring 5 is blocked by coarse aggregates, which is regarded as an abnormal situation; At this time, the vibration should be paused, the ring 5 should be gently moved to another position on the concrete surface, the vibration should be restarted and the timing should be restarted until the ring 5 is successfully immersed. ③ The vibration frequency and amplitude of the variable-frequency vibration equipment should be calibrated once every 3 months. If the usage frequency is high, it can be calibrated once a month.

[0069] While ensuring the test accuracy, this method greatly improves the test efficiency, and can, based on conventional indicators such as slump and Vebe consistency, realize multi-dimensional evaluation of the workability of concrete, including prediction and characterization of key parameters such as vibration time and floating slurry thickness, providing a scientific basis for vibration optimization and quality control during the construction process.

[0070] The specific calculation method of the cohesion of concrete is as follows: Before the ring 5 is placed on the concrete surface, it needs to be weighed first and the initial mass m0 is recorded. After the test is completed, the ring 5 and the slurry adhered to the ring 5 are weighed and m1 is recorded. Then, the mass of the slurry adhered to the ring m = m1 - m0 is calculated. The larger the value of the mass of the slurry adhered to the ring, the stronger the cohesion of the concrete.

[0071] The following is a detailed description in combination with the embodiment of shield segment concrete. The mix proportion of the shield segment concrete is as follows: per 1 m3, it contains 323 kg of P.I 52.5 cement, 149 kg of fly ash, 25 kg of silica fume, 741 kg of sand, 318 kg of 5 - 10 mm crushed stone, 751 kg of 10 - 20 mm crushed stone, 1.5 kg of polypropylene fiber, 40 kg of steel fiber, 150 kg of water, and 5 kg of water reducing agent, and the water - binder ratio is 0.30.

[0072] Take samples of the fresh concrete from the pouring site and conduct inspections of different work performances in the laboratory; in addition, record the entire pouring process of the corresponding segments in detail. According to the method for evaluating the work performance of shield segment concrete based on the ring test described above, after filling the concrete in the loading container 4 and fixing it on the table 106, the fresh concrete is leveled by vibration at a frequency of 40 Hz, and then the ring test piece is placed on the upper surface of the concrete and the vibration table is started for testing. The test frequency is 50 Hz and the maximum amplitude is 2 mm; in addition to the method for evaluating the work performance of concrete based on the ring test of the present invention, the slump and Vebe consistency are also tested by traditional methods. The results of each test are shown in Figures 6 to 13 .

[0073] From Figure 6 it can be seen that by fitting the Vebe consistency and the vibration time during the pouring process, the determination coefficient R 2 is 0.21, indicating that there is no obvious correlation between the two; as Figure 7 shown, by fitting the slump and the vibration time during the pouring process, the determination coefficient R 2 is 0.62, indicating that there is a weak correlation between the two. And from Figure 8 it can be seen that by fitting the mass of the slurry adhered to the ring, the immersion time of the ring and the vibration time during the pouring process, the determination coefficient R 2 is greater than 0.9 for all, indicating a high correlation among the mass of the slurry adhered to the ring, the immersion time of the ring and the vibration time during the pouring process. In addition, Figure 9 the results in show that the immersion time of the ring also indicates the ability of the concrete to pass through the steel bars. The smaller the immersion time of the ring, the better the fluidity of the concrete, the stronger the ability to pass through the steel bars, and the shorter the required vibration time, which corresponds to the experimental results.

[0074] Figure 10The figure shows the variation of the immersion time - vibration frequency sensitivity of the ring obtained at vibration frequencies of 40 Hz and 50 Hz with the vibration time during the pouring process. It can be seen from Figure 10 that there is also a good correlation between the immersion time - vibration frequency sensitivity of the ring and the vibration time during the pouring process. The greater the sensitivity of the immersion time of the ring to the vibration frequency indicates that the concrete is more affected by the vibration frequency. When the vibration frequency is increased during the pouring process, the pouring time and vibration time will be significantly reduced.

[0075] Figures 11 to 13 The figure shows the relationship between the workability control index and the floating slurry thickness of the segment. It can be seen from the figure that there is a certain correlation between the slump, Vebe consistency and the floating slurry thickness of the segment, but the correlation is weak, and the determination coefficient R 2 is 0.55; while the correlation between the mass of the slurry attached to the ring and the floating slurry thickness of the segment is better, and the determination coefficient R 2 is 0.95. As the mass of the slurry attached to the ring increases, the floating slurry thickness of the segment becomes larger and larger.

[0076] In summary, combined with Figures 6 to 13 the test results, it can be known that through the immersion time and the mass of the slurry attached to the ring obtained by the ring test, the cohesiveness and passability of the concrete can be accurately characterized, and the sensitivity of the concrete to the vibration frequency can be further quantified. The evaluation method of the present invention is significantly different from the traditional slump and Vebe consistency tests; different from the slump and Vebe consistency which can only statically characterize the single performance of the concrete, the method of the present invention can dynamically capture the performance changes of the concrete under vibration conditions, and can predict key parameters such as the vibration time and floating slurry thickness during the pouring process, comprehensively reflecting the dynamic work performance of the concrete, and providing more scientific and practical technical support for engineering practice.

[0077] Application Example

[0078] The present invention also proposes an application of the evaluation method for the work performance of shield segment concrete based on the ring test, including the application of predicting the vibration time and floating slurry thickness during the pouring process of fresh concrete based on the immersion time of the ring and the mass of the slurry attached to the ring.

[0079] Specifically, it includes the application of predicting the vibration time and floating slurry thickness during the casting process of fresh concrete based on the immersion time of the ring and the mass of the slurry adhered to the ring. The application process is as follows: while testing the ring, the vibration time, slump, Vebe consistency, and floating slurry thickness during the segment casting process of the same fresh concrete are tested according to the conventional method; and the mass of the slurry adhered to the ring, the immersion time of the ring, and the vibration time during the casting process are fitted to obtain the first relationship between the mass of the slurry adhered to the ring and the vibration time during the casting process, and the second relationship between the immersion time of the ring and the vibration time during the casting process; the mass of the slurry adhered to the ring and the floating slurry thickness are fitted to obtain the third relationship between the mass of the slurry adhered to the ring and the floating slurry thickness; then the vibration time during the casting process of fresh concrete can be predicted based on the mass of the slurry adhered to the ring, the immersion time of the ring, the first relationship, and the second relationship obtained from the ring test, and the floating slurry thickness during the casting process of fresh concrete can be predicted based on the mass of the slurry adhered to the ring obtained from the ring test and the third relationship. If the results predicted by the first relationship and the second relationship are inconsistent, the minimum value of the two predicted results is taken; in this way, the concrete can be vibrated according to this minimum value first. If the concrete does not meet the requirements of vibration compaction after vibration, the vibration can be continued on the concrete; if it is vibrated according to the maximum value between the two predicted results, the situation of excessive floating slurry thickness may occur.

[0080] As Figure 8 shown, in the first relationship, x is the mass of the slurry adhered to the ring, and y is the vibration time during the casting process. According to the fitting result, y = 146.06 + 5.01x. As Figure 9 shown, in the second relationship, x is the immersion time of the ring, and y is the vibration time during the casting process. According to the fitting result, y = 119.2 + 6.88x. As Figure 13 shown, in the third relationship, x is the mass of the slurry adhered to the ring, and y is the floating slurry thickness. According to the fitting result, y = 2.76 + 0.59x. During application, the mass of the slurry adhered to the ring and the immersion time of the ring obtained from the ring test are used as x and substituted into the first / second and third relationships to obtain the corresponding predicted results. The application of the present invention can accurately predict key parameters such as the vibration time and floating slurry thickness during the concrete casting process, thereby making up for the multi-dimensional work performance evaluation that cannot be provided by traditional methods, and is especially suitable for on-site rapid testing of special types of concrete such as shield segment concrete.

[0081] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A concrete working performance evaluation device based on a ring test, characterized in that: include: A loading container (4), wherein the loading container (4) is used to store fresh concrete; A vibration table, on which the loading container (4) is mounted, and the vibration table vibrates the loading container (4) at a stable vibration frequency; the vibration frequency is adjustable; A weighing device, the weighing device is used to weigh the mass of the ring (5) and the slurry attached to the ring; A timing device is used for timing.

2. The concrete working performance evaluation device based on the ring test according to claim 1 is characterized in that: The vibration table comprises a base (101), a table top (106) mounted on the base (101) via a spring (103), and a vibration mechanism fixed on the base (101) and connected to the table top (106); The loading container (4) is detachably fixed on the table (106) via a fixing bracket; the fixing bracket comprises at least two pairs of bracket screws (302) vertically mounted on the table (106), each pair of bracket screws (302) is provided with a same fixing plate (303), the fixing plate (303) is pressed against the top of the loading container (4) and is fixed by a locking nut (304) threadedly mounted on the bracket screw (302).

3. The concrete working performance evaluation device based on the ring test according to claim 1 is characterized in that: The concrete work performance evaluation device based on the ring test also includes a ring placing device, which is detachably arranged on a charging container (4) or a table (106) and is used to place the ring (5) horizontally on the upper surface of freshly mixed concrete in the charging container (4).

4. The concrete working performance evaluation device based on the ring test according to claim 1 is characterized in that: The circular ring delivery device comprises a frame plate (701), a plurality of vertical rods (711) rotatably mounted on the frame plate (701), and a synchronous rotation mechanism for driving the vertical rods (711) to rotate horizontally at the same time; the number of the vertical rods (711) is more than 3, and the vertical rods (711) are arranged in a circle; a support plate (712) is horizontally fixed at the bottom of the vertical rods (711), and the support plate (712) is used to support the circular ring (5); the height of the frame plate (701) or the support plate (712) is adjustable.

5. The concrete working performance evaluation device based on the ring test according to claim 4 is characterized in that: The synchronous rotation mechanism comprises a synchronous wheel (708) fixed on the vertical rod (711), a synchronous belt (702) connected to the synchronous wheel (708), and a paddle (706) fixed on the synchronous belt (702); the synchronous wheel (708) is rotatably mounted on the frame plate (701); a clamp is fixed on the upper surface of the synchronous wheel (708), and the clamp comprises a plurality of anchor petals (710), one of which is fixed on the upper surface of the synchronous wheel (708), and all of the anchor petals (710) are clamped on the vertical rod (711) by locking members (709) arranged on their peripheries.

6. A method for evaluating the working performance of shield segment concrete based on a ring test, characterized in that: The concrete working performance evaluation device based on the ring test as claimed in any one of claims 1 to 5 is used for evaluation, comprising the following steps: S1. Test preparation: using a weighing device to weigh the initial weight of the ring; filling the loading container (4) with fresh concrete and making the surface of the fresh concrete flat; adjusting the vibration frequency of the vibration table to the frequency and amplitude to be tested; S2. Gently place a ring (5) on the surface of fresh concrete in the loading container (4); start the vibration table and start timing; stop timing after the ring (5) is completely immersed in the fresh concrete, and obtain the immersion time of the ring; S3, slowly taking out the ring (5) from the fresh concrete, weighing and recording the weight when the slurry attached to the ring stops dripping; subtracting the initial weight of the ring from the weight to obtain the mass of the slurry attached to the ring; S4. Evaluate the cohesiveness and passability of the concrete based on the ring immersion time and the quality of the slurry to which the ring adheres.

7. The method for evaluating the working performance of shield segment concrete based on the ring test according to claim 6 is characterized in that: The outer diameter of the circular ring (5) is 100 to 200 mm, and the wire diameter is 8 to 12 mm; the surface of the circular ring (5) is rough or smooth.

8. The method for evaluating the working performance of shield segment concrete based on the ring test according to claim 6 is characterized by: The vibration table has an adjustable vibration frequency range of 0 to 50 Hz and an amplitude of 0.5 to 2 mm. The time from the completion of mixing of the fresh concrete sample to the start of testing is within 10 minutes. The volume of the fresh concrete is 1 / 2 to 2 / 3 of the capacity of the charging container (4).

9. The method for evaluating the working performance of shield segment concrete based on the ring test according to claim 6 is characterized by: The ring (5) is placed horizontally on the surface of fresh concrete; if the ring (5) fails to sink normally within a preset time range, the vibration is stopped, the ring (5) is taken out and cleaned; the ring (5) is transferred to another position on the surface of the fresh concrete, the vibration table is started and the timing is restarted until the ring (5) is successfully immersed in the fresh concrete.

10. An application of a method for evaluating the working performance of shield segment concrete based on a ring test, characterized in that: Including the application of predicting the vibration time and floating slurry thickness in the pouring process of fresh concrete based on the ring immersion time and the mass of the slurry attached to the ring; The application process is that, at the same time as the ring test, the vibration time, slump, Vebe consistency and laitance thickness of the same freshly mixed concrete during the casting process of the pipe segment are tested according to the conventional method; and the mass of the ring attached slurry, the ring immersion time and the vibration time during the casting process are fitted to obtain the first relationship between the mass of the ring attached slurry and the vibration time during the casting process, and the second relationship between the ring immersion time and the vibration time during the casting process; the mass of the ring attached slurry and the laitance thickness are fitted to obtain the third relationship between the mass of the ring attached slurry and the laitance thickness; the vibration time during the casting of the freshly mixed concrete can be predicted based on the mass of the ring attached slurry, the ring immersion time, the first relationship and the second relationship obtained from the ring test, and the laitance thickness during the casting of the freshly mixed concrete can be predicted based on the mass of the ring attached slurry obtained from the ring test and the third relationship.

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