Early crack resistance test device for concrete

Abstract

The utility model belongs to the technical field of concrete crack resistance tests, and discloses a concrete early-stage crack resistance test device which comprises a bearing platform, a test cavity, an air supply device and an air speed measuring device, the test cavity is arranged on the upper surface of the bearing platform and is used for accommodating a concrete test piece; the air supply device is arranged on the bearing platform, and an air outlet of the air supply device faces the test cavity; the air speed measuring device is arranged above the test cavity, is electrically connected with the air supply device and is used for measuring the air speed of the upper surface of the concrete test piece and feeding back the air speed to the air supply device. The device can automatically monitor the wind speed on the surface of the concrete test piece, ensures that test conditions meet standard requirements, and improves the accuracy of test results. In the test process, the requirement for manual operation is greatly reduced, operation is simpler and more convenient, automatic operation is achieved, labor cost is saved, the air supply device is provided with the wind dispelling net, the air speed on the surface of the concrete test piece is more uniform, and the influence on results is reduced.

Description

Technical Field

[0001] The utility model discloses a concrete early anti-cracking test device, belonging to the technical field of concrete anti-cracking tests. Background Art

[0002] Concrete is a general term for engineering composite materials that are made by bonding aggregates into a whole using cementitious materials. It refers to cement concrete that is made by using cement as the cementitious material, sand and stone as aggregates, and mixing them with water in a certain proportion, and then mixing, molding, and curing.

[0003] Early concrete cracks refer to cracks that occur in the early hydration process of concrete, that is, cracks that appear before the use load, even before the construction load, or even shortly after the formwork is removed. The appearance of cracks will directly affect the various properties and service life of the concrete structure. Therefore, the test of the early crack resistance of concrete is very important.

[0004] GB / T50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete" has formulated detailed rules for the early crack resistance test method of concrete, which stipulates that when testing concrete specimens, the wind direction should flow along the surface of the specimen. The "Hydraulic Concrete Test Procedure" DL / T5150-2017 requires that the wind speed at 100mm above the center of the specimen surface is 5m / s±0.5m / s. However, there is no special concrete early crack resistance test device in the prior art. When conducting early crack resistance tests on concrete, many testers only use fans to blow air to the specimens. The wind source provided by the fan is not uniform, and the flow direction and flow rate of the wind source provided are not easy to accurately adjust, and the fan opening and closing and air supply duration need to be manually controlled. Utility Model Content

[0005] The purpose of the utility model is to provide a concrete early crack resistance test device to solve the technical problem that the existing technology only uses a fan to blow air to the test piece, and the flow direction and flow rate of the wind source provided by the fan are not easy to accurately adjust. To achieve the above purpose, the utility model proposes a concrete early crack resistance test device, and the specific scheme is as follows:

[0006] A concrete early crack resistance test device, comprising: a bearing platform, a test chamber, an air supply device and a wind speed measuring device;

[0007] The test chamber is arranged on the upper surface of the bearing platform and is used to accommodate the concrete test piece;

[0008] The air supply device is arranged on the carrying platform, and the air outlet of the air supply device faces the test chamber;

[0009] The wind speed measuring device is arranged above the test chamber and is electrically connected to the air supply device, and is used to measure the wind speed on the upper surface of the concrete specimen and feed the wind speed back to the air supply device.

[0010] Preferably, the air supply device includes a controller and an air supply device;

[0011] The controller is electrically connected to the air supply device and the wind speed measuring device respectively;

[0012] The controller is used to adjust the output wind speed of the air feeder according to the wind speed fed back by the wind speed measuring device.

[0013] Preferably, the air feeder comprises a fan housing and a plurality of fans;

[0014] An air outlet is provided on one side surface of the fan housing;

[0015] The multiple fans are arranged in parallel in the fan housing, and the air outlet directions of the multiple fans are toward the air outlet.

[0016] Preferably, the air feeder further comprises an air dispersion net;

[0017] The wind-repelling net is fixedly connected to the fan housing and covers the air outlet.

[0018] Preferably, the wind speed measuring device comprises a gantry and an anemometer;

[0019] The two upright posts of the door frame are vertically arranged on both sides of the test chamber;

[0020] The crossbar of the door frame is horizontally arranged at the upper ends of the two columns across the test cavity;

[0021] The anemometer is suspended on the cross bar.

[0022] Preferably, the anemometer is telescopically suspended on the cross bar.

[0023] Preferably, the anemometer is suspended on the crossbar by a screw;

[0024] One end of the screw rod passes through the through hole on the cross bar;

[0025] The other end of the screw is connected to the anemometer.

[0026] Preferably, a plurality of support frames are provided on the lower surface of the carrying platform;

[0027] A movable pulley is arranged at one end of each support frame away from the carrying platform.

[0028] Preferably, the multiple support frames are retractable frames.

[0029] Preferably, the controller is provided with a display screen, an air supply duration knob and an air volume adjustment knob;

[0030] The display screen is electrically connected to the wind speed measuring device;

[0031] The air supply duration knob and the air volume adjustment knob are both connected to the air supply device.

[0032] Beneficial effects: The utility model can automatically monitor the wind speed on the surface of the concrete specimen, ensuring that the test conditions meet the specification requirements and improving the accuracy of the test results. During the test, the requirements for manual operation are greatly reduced, the operation is simpler, the automatic operation is realized, and the labor cost is saved. The air supply device of the utility model is provided with a ventilating net to make the wind speed on the surface of the concrete specimen more uniform and reduce the impact on the results. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a top view schematic diagram of the anti-crack test device in the embodiment of the utility model;

[0034] Figure 2 for Figure 1 Schematic diagram of the middle BB section;

[0035] Figure 3 for Figure 1 Schematic diagram of the middle AA section;

[0036] Figure 4 This is a left side schematic diagram of a controller in an embodiment of the utility model;

[0037] Figure 5 It is a schematic diagram of the right side view of the controller in the embodiment of the utility model.

[0038] In the figure: 1. Carrying platform; 2. Air supply device; 3. Wind speed measuring device; 4. Controller; 5. Test chamber; 6. Concrete specimen; 7. Control transmission line; 8. Wind speed transmission line; 102. Support frame; 103. Moving pulley; 201. Air supply device; 202. Air supply support platform; 301. Anemometer; 302. Nut; 303. Screw; 304. Door frame; 401. Display screen; 402. Air volume adjustment knob; 403. Air supply duration knob; 404. Wind speed monitoring on / off knob; 405. Switch knob; 406. Charging port; 407. Anemometer connection interface. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in combination with specific implementation methods. It should be understood that the specific implementation methods described here are only used to explain the utility model and do not limit the protection scope of the utility model.

[0040] like Figure 1-3 As shown, in one embodiment, a concrete early crack resistance test device includes: a bearing platform 1, a test cavity 5, an air supply device 2 and a wind speed measuring device 3; the test cavity 5 is arranged on the upper surface of the bearing platform 1, and is used to accommodate a concrete specimen 6; the air supply device 2 is arranged on the bearing platform 1, and the air outlet of the air supply device 2 faces the test cavity 5; the wind speed measuring device 3 is arranged above the test cavity 5, and is electrically connected to the air supply device 2, and is used to measure the wind speed on the upper surface of the concrete specimen 6 and feed the wind speed back to the air supply device 2.

[0041] The utility model sets a test cavity 5 on the bearing platform 1, wherein the bearing platform 1 is made of high-strength materials such as metal material and steel material. In this embodiment, its thickness is 10mm. The test cavity 5 is a test mold for making a concrete specimen 6, and its shape is determined according to the test requirements. In this embodiment, it is a rectangular mold. An air supply device 2 is also set on the bearing platform 1, and the air outlet of the air supply device 2 faces the test cavity 5, which is used to deliver the wind speed that meets the test requirements to the concrete specimen 6 during the crack resistance test. A wind speed measuring device 3 is set above the concrete specimen 6, and the wind speed measuring device 3 is electrically connected to the air supply device 2. The wind speed measuring device 3 is used to measure the wind speed above the concrete specimen 6, and feed the wind speed back to the air supply device 2, and the air supply device 2 adjusts its output wind speed according to the preset requirements. Specifically, in this embodiment, the wind speed measuring device 3 is set 100mm above the center of the upper surface of the concrete specimen 6 according to the test requirements.

[0042] In a further embodiment, the air supply device 2 includes a controller 4 and an air supply device 201; the controller 4 is connected to the air supply device 201 and the wind speed measuring device 3 respectively; the controller 4 is used to adjust the output wind speed of the air supply device 201 according to the wind speed feedback from the wind speed measuring device 3.

[0043] Specifically, in this embodiment, the air supply device 2 includes a controller 4 and an air supply 201. The controller 4 is connected to the air supply 201 and the wind speed measuring device 3, and is used to adjust the output wind speed of the air supply 201 according to the wind speed fed back by the wind speed measuring device 3. Specifically, in this embodiment, according to the test requirements, the wind speed at 100mm above the center of the upper surface of the concrete specimen 6 is 5m±0.5m / s. The wind speed measuring device 3 feeds back the measured real-time wind speed to the controller 4. The controller 4 determines whether the test requirements are met according to the real-time wind speed, that is, whether the real-time wind speed is within the range of 5m±0.5m / s. If yes, no adjustment is made. If not, the controller 4 adjusts the output wind speed of the air supply device 2 so that the wind speed delivered to the top of the concrete specimen 6 meets the test requirements. Specifically, in this embodiment, the controller 4 is connected to the air supply 201 through a control transmission line 7, and the controller 4 is connected to the wind speed measuring device 3 through a wind speed transmission line 8.

[0044] In a further embodiment, the air feeder 201 includes a fan housing and a plurality of fans; an air outlet is provided on one side surface of the fan housing; the plurality of fans are arranged in parallel in the fan housing, and the air outlet directions of the plurality of fans are toward the air outlet.

[0045] Specifically, the air supply device 201 in this embodiment includes a fan housing and multiple fans. The multiple fans are evenly arranged in parallel in the fan housing, and their air outlet directions are toward the air outlet, and the air outlet is toward the test chamber 5. The air supply device 201 is used to supply air to the concrete specimen 6. In order to ensure the air supply height, the air supply device 201 in this embodiment also includes an air supply support platform 202 for supporting the air supply device 201.

[0046] In a further embodiment, the air supply device 201 further includes an air-dispersing net; the air-dispersing net is fixedly connected to the fan housing and covers the air outlet.

[0047] In order to ensure uniform air flow from the air outlet and uniform wind force reaching the concrete specimen 6, a ventilation net is fixed at the air outlet. Figure 3 As shown (controller 4 is not shown), specifically, in this embodiment, the wind-repelling net is a uniform mesh grid.

[0048] In a further embodiment, the wind speed measuring device 3 includes a gantry 304 and an anemometer 301; two columns of the gantry 304 are vertically arranged on both sides of the test chamber 5; a crossbar of the gantry 304 is horizontally arranged at the upper ends of the two columns across the test chamber 5; and the anemometer 301 is suspended on the crossbar.

[0049] Specifically, Figure 2 As shown, this embodiment further includes an anemometer 301 and a gantry 304, wherein two upright posts of the gantry 304 are vertically arranged on both sides of the test chamber 5; a crossbar of the gantry 304 is horizontally arranged at the upper ends of the two upright posts across the test chamber 5; and the anemometer 301 is suspended on the crossbar. The gantry 304 is used to suspend the anemometer 301. One end of the two upright posts away from the crossbar is fixed to the bearing platform 1 by bolts.

[0050] In a further embodiment, the anemometer 301 can be telescopically suspended on the crossbar.

[0051] In order to facilitate the adjustment of the distance between the anemometer 301 and the concrete specimen 6 so as to meet the test requirements, the utility model can be telescopically suspended on the crossbar. Specifically, in this embodiment, the anemometer 301 is 100 mm away from the upper surface of the concrete specimen 6.

[0052] In a further embodiment, the anemometer 301 is suspended on the crossbar by a screw rod 303 ; one end of the screw rod 303 passes through a through hole on the crossbar; and the other end of the screw rod 303 is connected to the anemometer 301 .

[0053] In order to facilitate the preparation of the concrete specimen 6, in this embodiment, the anemometer 301 is suspended on the crossbar by means of a screw 303. The crossbar passes through the through hole on the crossbar, one end of which is connected to the anemometer 301, and the other end is provided with a nut 302. The nut 302 is located on the upper surface of the crossbar, and the screw 303 is fixed on the crossbar. The distance between the anemometer 301 and the concrete specimen 6 can be adjusted by the position of the nut 302 on the screw 303. At the same time, when preparing the concrete specimen 6, the wind speed measuring device 3 can be removed to facilitate construction or placement of the test chamber 5.

[0054] In a further embodiment, a plurality of support frames 102 are disposed on the lower surface of the carrying platform 1 ; a movable pulley 103 is disposed at one end of each support frame 102 away from the carrying platform 1 .

[0055] Specifically, Figure 2-3 As shown, in this embodiment, a support frame 102 and a movable pulley 103 are also included to support the bearing platform 1 and facilitate the movement of the test device.

[0056] In a further embodiment, the plurality of support frames 102 are retractable frames.

[0057] In the utility model, for the convenience of operation, the support frame 102 is a retractable frame. Specifically, in this embodiment, the support frame 102 is two groups of cross-connected door-type frames, and a connecting axis is set at the intersection of the two groups of door-type frames, which adjusts the height of the support frame 102 through the angle between the two groups of door-type frames.

[0058] In a further embodiment, the controller 4 is provided with a display screen 401, an air supply duration knob 403 and an air volume adjustment knob 402; the display screen 401 is electrically connected to the wind speed measuring device 3; the air supply duration knob 403 and the air volume adjustment knob 402 are both connected to the air supply device 201.

[0059] Specifically, Figure 4-5 As shown, this embodiment also includes a display screen 401, an air supply duration knob 403 and an air volume adjustment knob 402; the display screen 401 is electrically connected to the wind speed measuring device 3; the display screen 401 is used to display the wind speed fed back by the anemometer 301 and the current output wind speed of the fan in real time. The air supply duration knob 403 and the air volume adjustment knob 402 are both connected to the air supply device 201. The air supply duration knob 403 can set the air supply duration to save labor costs. The air volume adjustment knob 402 is used to manually adjust the air volume as a backup knob. As shown Figure 4 and Figure 5 As shown, in this embodiment, the controller 4 is also provided with a switch knob 405, a wind speed monitoring on / off knob 404, a charging port 406, and an anemometer connection interface 407. Among them, the display screen 401 in this embodiment is also provided with an air supply duration adjustment interface, an air volume adjustment interface, a switch interface, a wind speed interface, and a wind speed monitoring on / off interface.

[0060] The following is a test process based on the crack resistance test device of this embodiment.

[0061] Step 1:

[0062] According to the requirements of DL / T5150-2017 "Testing Procedures for Hydraulic Concrete", P·LH 42.5 low-heat silicate cement, F-type grade I fly ash, 5-20mm and 20-40mm artificial coarse aggregates and 0-5mm artificial sand, of which the content of artificial sand and gravel powder is 16.8%, HLC-IX type polycarboxylic acid high-performance water reducer (retarded setting type) is used as an admixture, and HLC-AE610 type air entraining agent is used to mix concrete;

[0063] Step 2: Place the fresh concrete mixture into the test chamber 5 and vibrate it to make it dense.

[0064] Step 3: Place the vibrated and compacted concrete together with the test mold in the center of the test platform and smooth the surface.

[0065] Step 4: Adjust the screw rod 303 of the anemometer 301 so that the distance from the bottom of the anemometer 301 to the surface of the specimen is 100 mm.

[0066] Step 5: 30 minutes after the specimen is formed, start the control panel and adjust the wind speed to ensure that the wind speed is 5m / s±0.5m / s 100mm above the center of the specimen surface and the wind direction is parallel to the specimen surface.

[0067] Step 6: Set the required air supply duration in the control panel and start it.

[0068] Step 7: When the set time is reached, the fan automatically stops blowing.

[0069] Step 8: "Hydraulic Concrete Test Procedure" DL / T5150-2017 requires testing the width and length of surface cracks of the specimen.

[0070] Step 9: Test results

[0071] According to the formula given in "Hydraulic Concrete Test Code" DL / T5150-2017:

[0072] The average cracking area of ​​each crack is calculated according to formula 1-1:

[0073]

[0074] The number of cracks per unit area is calculated according to formula 1-2:

[0075]

[0076] The total cracking area per unit area is calculated according to formula 1-3:

[0077] c=ab 1-3

[0078] Where: W i —The maximum width of the i-th crack (mm), L i —length of the i-th crack (mm), N—total number of cracks (cracks), A—area of ​​the plate (0.48m 2 ), a—average cracking area of ​​each crack (mm 2 / line), b—number of cracks per unit area (line / m 2 ), c—total cracking area per unit area (mm 2 / m 2 ).

[0079] Step 10: Extract test results.

[0080] The utility model can automatically monitor the wind speed on the surface of the concrete specimen 6, ensuring that the test conditions meet the specification requirements and improving the accuracy of the test results. During the test, the requirements for manual operation are greatly reduced, the operation is simpler, the automatic operation is realized, and the labor cost is saved. The air supply device 2 of the utility model is provided with a ventilating net to make the wind speed on the surface of the concrete specimen 6 more uniform, reducing the influence on the results.

[0081] The above are only several embodiments of the utility model, and do not limit the utility model in any form. Although the utility model is disclosed as above in the preferred embodiments, it is not used to limit the utility model. Any technician familiar with this profession, without departing from the scope of the technical solution of the utility model, makes slight changes or modifications using the technical contents disclosed above, which are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A concrete early crack resistance test device, characterized in that: include: Load-bearing platform, test chamber, air supply device and wind speed measuring device; The test chamber is arranged on the upper surface of the bearing platform and is used to accommodate the concrete test piece; The air supply device is arranged on the carrying platform, and the air outlet of the air supply device faces the test chamber; The wind speed measuring device is arranged above the test chamber and is electrically connected to the air supply device, and is used to measure the wind speed on the upper surface of the concrete specimen and feed the wind speed back to the air supply device.

2. The concrete early cracking test device according to claim 1 is characterized in that: The air supply device includes a controller and an air feeder; The controller is electrically connected to the air supply device and the wind speed measuring device respectively; The controller is used to adjust the output wind speed of the air feeder according to the wind speed fed back by the wind speed measuring device.

3. The concrete early cracking test device according to claim 2, characterized in that: The air feeder comprises a fan housing and a plurality of fans; An air outlet is provided on one side surface of the fan housing; The multiple fans are arranged in parallel in the fan housing, and the air outlet directions of the multiple fans are toward the air outlet.

4. The concrete early cracking test device according to claim 3 is characterized in that: The air feeder also includes an air dispersion net; The wind-repelling net is fixedly connected to the fan housing and covers the air outlet.

5. The concrete early cracking test device according to claim 1, characterized in that: The wind speed measuring device comprises a gantry and an anemometer; The two upright posts of the gantry are vertically arranged on both sides of the test chamber; The crossbar of the door frame is horizontally arranged at the upper ends of the two columns across the test cavity; The anemometer is suspended on the cross bar.

6. The concrete early cracking test device according to claim 5, characterized in that: The anemometer is telescopically suspended on the crossbar.

7. The concrete early cracking test device according to claim 6, characterized in that: The anemometer is suspended on the crossbar via a screw; One end of the screw rod passes through the through hole on the cross bar; The other end of the screw is connected to the anemometer.

8. The concrete early cracking test device according to claim 1, characterized in that: A plurality of support frames are arranged on the lower surface of the carrying platform; A movable pulley is arranged at one end of each support frame away from the carrying platform.

9. The concrete early cracking test device according to claim 8, characterized in that: The multiple support frames are retractable frames.

10. The concrete early cracking test device according to claim 2, characterized in that: The controller is provided with a display screen, an air supply duration knob and an air volume adjustment knob; The display screen is electrically connected to the wind speed measuring device; The air supply duration knob and the air volume adjustment knob are both connected to the air supply device.

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