Device and method for rapidly evaluating physical and mechanical properties of waste concrete

Abstract

The invention discloses a device and a method for rapidly evaluating physical and mechanical properties of waste concrete. Comprising a test box cover plate, a blower nozzle, a drying test bin top plate, a heating device, an aggregate bin, a drying test bin water outlet, a water storage tank, an aggregate bin bottom plate with a force sensor, a vibrating screen, a screen residue bin bottom plate with a force sensor, a pressurizing device, a water saturation test bin water outlet, a water saturation test bin top plate, a water injection nozzle, an infrared distance measuring sensor, a pressurizing opening and a control system. The drying test bin is connected with the water saturation test bin. According to the invention, the compressive strength, softening coefficient and crushing index of the waste concrete can be tested, the test time is obviously shortened, the intelligent degree of the test process is high, the physical and mechanical properties of the waste concrete can be more comprehensively evaluated, and the resource utilization of the waste concrete is promoted.

Description

Technical Field

[0001] The invention relates to the field of waste concrete material property testing, and in particular to a device and method for quickly evaluating the physical and mechanical properties of waste concrete. Background Art

[0002] By the end of 2023, my country's construction waste production will be about 3.45 billion tons, accounting for 40% of the total urban waste. As a result, a large amount of waste concrete has been generated. Recycling it as a resource can promote the green development of the construction industry. However, the service environment of concrete structures is complex. If it is in a chloride environment, a carbonization environment, or a freeze-thaw environment, the mechanical properties and durability of the concrete will be reduced, and the performance of the recycled aggregates crushed from it will be difficult to meet the needs of the project. The range of values ​​for the crushing index is specified in GB / T 25177 "Recycled Coarse Aggregates for Concrete", but there are no clear regulations on physical and mechanical performance indicators such as compressive strength and softening coefficient. At the same time, each indicator needs to be measured separately, the test time is long, and the degree of automation of the test process is not high.

[0003] Therefore, how to more comprehensively evaluate the physical and mechanical properties of waste concrete and simultaneously conduct rapid and intelligent detection is an urgent problem that technicians in this field need to solve. Summary of the invention

[0004] In view of this, the present invention proposes a device and method for quickly evaluating the physical and mechanical properties of waste concrete.

[0005] The present invention adopts the following technical solution:

[0006] A device and method for quickly evaluating the physical and mechanical properties of waste concrete, comprising a test box cover, an air blast, a dry test bin top plate, a heating device, a first aggregate bin, a dry test bin drain, a water storage tank, an aggregate bin bottom plate with a force sensor, a vibrating screen, a sieve bin bottom plate with a force sensor, a pressurizing device, a saturated test bin drain, a saturated test bin top plate, a water injection port, an infrared distance measuring sensor, a pressurizing port, a control system, an air blower, a dry test bin, a saturated test bin, and a water injection device.

[0007] Start the control system, rotate the top plate of the dry test bin and the top plate of the saturated test bin by 180 degrees, weigh 3-5 kg ​​of 5mm-20mm coarse aggregate crushed from waste concrete and put it into the dry test bin and the saturated test bin. Then the top plate of the dry test bin rotates 180 degrees to reset, and the test box cover is connected to the test box. Start the blower to ventilate the dry test bin, and the heating device starts to work. The water flows to the water storage tank through the drain port of the dry test bin. When the force sensor located on the bottom plate of the aggregate bin no longer changes, the drain port of the dry test bin is closed, the blower and the heating device stop working, and the force value F1 is recorded. At this time, the waste concrete aggregate is in a completely dry state. At the same time, the pressure device pressurizes the water injection device through the rubber hose, and water is injected into the saturated test bin through the second rubber hose in the test box cover. The infrared ranging sensor monitors the change of the liquid level, and the water injection is stopped when the liquid level reaches 150mm. The rubber hose between the pressure device and the water injection device is closed, and the pressure device pressurizes the saturated test bin through the third rubber hose in the test box cover. When the data of the infrared ranging sensor shows that the liquid level no longer changes, the pressure is stopped, the drain port of the saturated test bin is opened, and the excess water and pressure are discharged. When the force sensor reading on the bottom plate of the aggregate bin no longer changes, the force value F2 is recorded. At this time, the waste concrete aggregate is in a completely saturated state. The top plate of the saturated test bin rotates 180 degrees to reset. The top plates of the dry test bin and the saturated test bin are both equipped with displacement sensors, which are loaded downward through the hydraulic devices on both sides, and the bottom plate of the aggregate bin records the force value during the loading process. The control system records the load-displacement curve during the loading process. When the displacement reaches 30mm, the loading is stopped, the force values ​​F3 and F4 are recorded, and the top plates of the dry test bin and the saturated test bin are reset. The bottom plate of the aggregate bin with a force sensor rotates 180 degrees to make the waste concrete aggregate fall on the vibrating screen, and the screen mesh aperture is 2.36mm. After that, the bottom plate of the aggregate bin is reset, and the vibrating screen starts working, with a vibration frequency of 20Hz and a vibration amplitude of 5mm. Particles with a particle size less than 2.36mm fall onto the bottom plate of the sieve bin with a force sensor. When the force value no longer changes, the vibration is stopped, and the readings F5 and F6 of the dry test bin and the saturated test bin are recorded. At this time, the vibrating screen and the bottom plate of the sieve bin are rotated 180 degrees to make the aggregate fall. The test is completed and the next set of tests can be carried out.

[0008] The physical and mechanical properties of the waste concrete are evaluated by its strength, crushing index and softening coefficient in dry state.

[0009] The strength of waste concrete in dry state can be calculated using formula (1):

[0010]

[0011] Where: σ is the strength of waste concrete; A is the cross-sectional area of ​​the aggregate bin, the diameter of the aggregate bin is 100 mm, and the area is 7854 mm 2.

[0012] The softening coefficient of waste concrete can be calculated using formula (2):

[0013]

[0014] Where: K is the softening coefficient of waste concrete; F2 is the weight of waste concrete aggregate in a saturated state; F4 is the force value when the displacement of the top plate of the saturated test bin reaches 30 mm.

[0015] The crushing index of waste concrete in dry state can be calculated using formula (3):

[0016]

[0017] Where: δ is the crushing index of waste concrete; F5 is the bottom plate force value of the sieve bin in the drying test bin.

[0018] When σ is greater than 20 MPa, K is greater than 0.75, and δ is less than 15%, the physical and mechanical properties of the waste concrete meet the requirements and can be used for the preparation of recycled concrete.

[0019] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a device and method for quickly evaluating the physical and mechanical properties of waste concrete, which has the following beneficial effects:

[0020] 1. The present invention can comprehensively detect the compressive strength, softening coefficient and crushing index of waste concrete. Through the simultaneous pressurization, recording and vibration of the dry test chamber and the saturated test chamber, it can more comprehensively measure its physical and mechanical properties and provide a reference for the resource utilization of waste concrete.

[0021] 2. The present invention can perform rapid detection of waste concrete by blowing air into the dry test chamber for heating and injecting water into the saturated test chamber for pressurization, thereby greatly shortening the detection time.

[0022] 3. The test device in the present invention is highly automated and intelligent, and all operations can be realized by the control system issuing instructions to manipulate various components, fully ensuring the synchronization of the dry test chamber and the saturated test chamber. At the same time, it has multiple load and displacement sensors, and the relevant data are synchronously returned to the control system to facilitate data analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0024] Figure 1 It is a front view of the test device in the present invention.

[0025] Figure 2 It is a top view of the test device in the present invention.

[0026] 1. Test chamber cover, 2. Air blast, 3. Dry test chamber top plate, 4. Heating device, 5. Aggregate chamber, 6. Dry test chamber drain, 7. Water storage tank, 8. Aggregate chamber bottom plate with force sensor, 9. Vibrating screen, 10. Screen chamber bottom plate with force sensor, 11. Pressurizing device, 12. Saturated test chamber drain, 13. Saturated test chamber top plate, 14. Water injection port, 15. Infrared ranging sensor, 16. Pressurizing port, 17. Control system, 18. Blower, 19. Dry test chamber, 20. Saturated test chamber, 21. Water injection device. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] See also Figure 1 and Figure 2 As shown, the present invention discloses a device and method for quickly evaluating the physical and mechanical properties of waste concrete, comprising a test box cover 1, an air blast port 2, a drying test bin top plate 3, a heating device 4, an aggregate bin 5, a drying test bin drain port 6, a water storage tank 7, an aggregate bin bottom plate 8 with a force sensor, a vibrating screen 9, a sieve bin bottom plate 10 with a force sensor, a pressurizing device 11, a saturated test bin drain port 12, a saturated test bin top plate 13, a water injection port 14, an infrared ranging sensor 15, a pressurizing port 16, a control system 17, an air blower 18, a drying test bin 19, a saturated test bin 20, and a water injection device 21.

[0029] The dry test chamber 19 and the saturated test chamber 20 are respectively arranged on both sides of the waste concrete physical and mechanical properties rapid assessment device and are covered by the test box cover 1;

[0030] The test box cover 1 includes an air blast port 2, a water injection port 14, an infrared distance sensor 15, and a pressurization port 16;

[0031] The drying test bin 19 includes a drying test bin top plate 3, a heating device 4, an aggregate bin 5, a drying test bin drain port 6, a water storage tank 7, an aggregate bin bottom plate 8 with a force sensor, a vibrating screen 9, and a sieve bin bottom plate 10 with a force sensor;

[0032] The saturated test bin 20 includes an aggregate bin 5, an aggregate bin bottom plate 8 with a force sensor, a vibrating screen 9, a sieve bin bottom plate 10 with a force sensor, a pressurizing device 11, a saturated test bin drain port 12, and a saturated test bin top plate 13;

[0033] It also includes a control system 17 , a blower 18 , and a water injection device 21 .

[0034] The test only requires 3 to 5 kg of waste concrete aggregate to conduct a comprehensive evaluation of its compressive strength, softening coefficient and crushing index.

[0035] During the test, the aggregate in the drying test bin 19 is ventilated and heated to keep it in a completely dry state.

[0036] During the test, the aggregate in the saturated test bin 20 is pressurized with water to make it saturated with water.

[0037] The dry test bin top plate 3 and the saturated test bin top plate 13 are both installed with displacement sensors, which are loaded downwards through hydraulic devices on both sides, and the aggregate bin bottom plate 8 records the force value during the loading process; the control system 17 can record the load-displacement curve during the loading process.

[0038] The mesh diameter of the vibrating screen 9 is 2.36 mm, the vibration frequency is 20 Hz, and the vibration amplitude is 5 mm.

[0039] All operations can be realized by the control system 17 issuing instructions to manipulate various components. At the same time, there are multiple load and displacement sensors, and relevant data are synchronously returned to the control system 17.

[0040] The specific steps of this embodiment are:

[0041] S1: Start the control system 17 to rotate the top plate 3 of the dry test bin and the top plate 13 of the saturated test bin by 180 degrees, and weigh 5 kg of 5 mm to 20 mm coarse aggregates crushed from waste concrete and put them into the dry test bin 19 and the saturated test bin 20;

[0042] S2: The top plate 3 of the drying test chamber is rotated 180 degrees to reset, and the test chamber cover plate 1 is connected to the test chamber;

[0043] S3: Start the blower 18 to ventilate the drying test chamber 19, and the heating device 4 starts to work. The water flows to the water storage tank 7 through the drying test chamber drain port 6. When the reading of the force sensor located on the bottom plate 8 of the aggregate chamber no longer changes, the drying test chamber drain port 6 is closed, the blower 18 and the heating device 4 stop working, and the force value F is recorded. 1；

[0044] S4: The pressurizing device 11 pressurizes the water injection device 21 through the rubber hose, and water is injected into the saturated test chamber 20 through the second rubber hose in the test box cover 1; the infrared ranging sensor 15 monitors the change of the liquid level, and stops injecting water when the liquid level reaches 150mm;

[0045] S5: The rubber hose between the pressurizing device 11 and the water injection device 21 is closed, and the pressurizing device 11 pressurizes the saturated test chamber 20 through the third rubber hose in the test chamber cover 1; when the data of the infrared ranging sensor 15 shows that the liquid level no longer changes, the pressurization is stopped;

[0046] S6: Open the drain port 12 of the saturated test bin to discharge the water and pressure. When the reading of the force sensor on the bottom plate 8 of the aggregate bin no longer changes, record the force value F. 2；

[0047] S7: The top plate 13 of the saturated test chamber rotates 180 degrees to reset;

[0048] S8: The top plate 3 of the dry test bin and the top plate 13 of the saturated test bin are both equipped with displacement sensors, which are loaded downwards through the hydraulic devices on both sides, and the bottom plates 8 of the aggregate bins of the dry test bin 19 and the saturated test bin 20 both record the force values ​​during the loading process; the control system 17 records the load-displacement curve during the loading process, and when the displacement reaches 30 mm, the loading is stopped, and the force values ​​F3 and F4 of the force sensors of the bottom plates 8 of the aggregate bins of the dry test bin 19 and the saturated test bin 20 are recorded respectively, and the top plate 3 of the dry test bin and the top plate 13 of the saturated test bin are reset;

[0049] S9: The aggregate bin bottom plate 8 with the force sensor rotates 180 degrees, so that the waste concrete aggregate falls onto the vibrating screen 9;

[0050] S10: The bottom plate 8 of the aggregate bin is reset, and the vibrating screen starts to work, with a vibration frequency of 20 Hz and a vibration amplitude of 5 mm;

[0051] S11: When the force value no longer changes, stop vibrating and record the readings F5 and F6 of the sieve plate 10 of the dry test chamber 19 and the saturated test chamber 20 respectively. 6；

[0052] S12: The vibrating screen 9 and the bottom plate 10 of the sieve bin rotate 180 degrees to make the aggregate fall down, and the test is completed;

[0053] The compressive strength of waste concrete in dry state can be calculated using formula (1);

[0054]

[0055] Where: σ is the compressive strength of waste concrete; F1 is the weight of waste concrete aggregate in a completely dry state; F3 is the force value when the displacement of the top plate (3) of the drying test bin reaches 30 mm; A is the cross-sectional area of ​​the aggregate bin;

[0056] The softening coefficient of waste concrete can be calculated using formula (2);

[0057]

[0058] Where: K is the softening coefficient of waste concrete; F2 is the weight of waste concrete aggregate in a saturated state; F4 is the force value when the displacement of the top plate 13 of the saturated test bin reaches 30 mm;

[0059] The crushing index of waste concrete in dry state can be calculated using formula (3);

[0060]

[0061] Wherein: δ is the crushing index of waste concrete; F5 is the force value of the bottom plate 10 of the sieve bin in the drying test bin 19.

[0062] The test results are shown in Table 1.

[0063]

[0064] The test results show that the waste concrete in this embodiment has a compressive strength greater than 20 MPa, a softening coefficient greater than 0.75, a crushing index less than 15%, and physical and mechanical properties that meet the requirements, and can be used for the preparation of recycled concrete.

[0065] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0066] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device for rapid evaluation of physical and mechanical properties of waste concrete, characterized in that: The device comprises a test box cover (1), a dry test chamber (19) and a saturated water test chamber (20), wherein the dry test chamber (19) and the saturated water test chamber (20) are respectively arranged on both sides of the device for rapid assessment of physical and mechanical properties of waste concrete and are covered by the test box cover (1); The test box cover (1) comprises an air blast port (2), a water injection port (14), an infrared distance measuring sensor (15), and a pressurizing port (16); The drying test bin (19) comprises a drying test bin top plate (3), a heating device (4), an aggregate bin (5), a drying test bin drain outlet (6), a water storage tank (7), an aggregate bin bottom plate (8) with a force sensor, a vibrating screen (9), and a sieve bin bottom plate (10) with a force sensor; The saturated test bin (20) comprises an aggregate bin (5), an aggregate bin bottom plate (8) with a force sensor, a vibrating screen (9), a sieve bin bottom plate (10) with a force sensor, a pressurizing device (11), a saturated test bin drain port (12), and a saturated test bin top plate (13); It also includes a control system (17), a blower (18), and a water injection device (21).

2. The device for rapid evaluation of physical and mechanical properties of waste concrete according to claim 1, characterized in that: The test only requires 3 to 5 kg of waste concrete aggregate to conduct a comprehensive evaluation of its compressive strength, softening coefficient and crushing index.

3. The device for rapid evaluation of physical and mechanical properties of waste concrete according to claim 1, characterized in that: During the test, the aggregate in the drying test bin (19) is ventilated and heated to keep it in a completely dry state.

4. The device for rapid evaluation of physical and mechanical properties of waste concrete according to claim 1, characterized in that: During the test, water is injected into the aggregate in the saturated test bin (20) to increase the pressure so that the aggregate is in a saturated state.

5. The device for rapid evaluation of physical and mechanical properties of waste concrete according to claim 1, characterized in that: The dry test bin top plate (3) and the saturated test bin top plate (13) are both equipped with displacement sensors, which are loaded downwards through hydraulic devices on both sides, and the aggregate bin bottom plate (8) records the force value during the loading process; the control system (17) can record the load-displacement curve during the loading process.

6. The device for rapid evaluation of physical and mechanical properties of waste concrete according to claim 1, characterized in that: The mesh diameter of the vibrating screen (9) is 2.36 mm, the vibration frequency is 20 Hz, and the vibration amplitude is 5 mm.

7. The device for rapid evaluation of physical and mechanical properties of waste concrete according to claim 1, characterized in that: All operations can be realized by the control system (17) issuing instructions to manipulate various components. At the same time, there are multiple load and displacement sensors, and relevant data are synchronously returned to the control system (17).

8. A method for quickly evaluating the physical and mechanical properties of waste concrete using the device as claimed in claim 1, characterized in that: The steps include: S1: Start the control system (17), rotate the top plate (3) of the dry test bin and the top plate (13) of the saturated test bin by 180 degrees, weigh 5 kg of 5 mm to 20 mm coarse aggregate crushed from waste concrete and put them into the dry test bin (19) and the saturated test bin (20); S2: The top plate (3) of the drying test chamber is rotated 180 degrees to reset, and the test chamber cover (1) is connected to the test chamber; S3: Start the blower (18) to ventilate the drying test chamber (19), and the heating device (4) starts to work, and the water flows to the water storage tank (7) through the drying test chamber drain port (6). When the reading of the force sensor located on the bottom plate (8) of the aggregate chamber no longer changes, the drying test chamber drain port (6) is closed, the blower (18) and the heating device (4) stop working, and the force value F is recorded. 1； S4: the pressurizing device (11) applies pressure to the water injection device (21) through the rubber hose, and water is injected into the saturated test chamber (20) through the second rubber hose in the test chamber cover (1); the infrared distance sensor (15) monitors the change of the liquid level, and stops injecting water when the liquid level reaches 150 mm; S5: the rubber hose between the pressurizing device (11) and the water injection device (21) is closed, and the pressurizing device (11) pressurizes the saturated test chamber (20) through the third rubber hose in the test chamber cover (1); when the data of the infrared distance sensor (15) shows that the liquid level no longer changes, the pressurization is stopped; S6: Open the drain port (12) of the saturated test bin to discharge the water and pressure. When the reading of the force sensor on the bottom plate (8) of the aggregate bin no longer changes, record the force value F. 2； S7: The top plate (13) of the saturated test chamber is rotated 180 degrees and reset; S8: The top plate (3) of the dry test bin and the top plate (13) of the saturated test bin are both equipped with displacement sensors, and load is applied downwards through hydraulic devices on both sides. The bottom plates (8) of the aggregate bins of the dry test bin (19) and the saturated test bin (20) both record the force values ​​during the loading process; the control system (17) records the load-displacement curve during the loading process. When the displacement reaches 30 mm, the loading is stopped, and the force values ​​F3 and F4 of the force sensors of the bottom plates (8) of the aggregate bins of the dry test bin (19) and the saturated test bin (20) are recorded respectively, and the top plate (3) of the dry test bin and the top plate (13) of the saturated test bin are reset; S9: The aggregate bin bottom plate (8) with the force sensor rotates 180 degrees, so that the waste concrete aggregate falls onto the vibrating screen (9); S10: the bottom plate (8) of the aggregate bin is reset, and the vibrating screen starts to work, with a vibration frequency of 20 Hz and a vibration amplitude of 5 mm; S11: When the force value no longer changes, stop the vibration and record the readings F5 and F6 of the sieve plate (10) of the dry test chamber (19) and the saturated test chamber (20) respectively. 6； S12: The vibrating screen (9) and the bottom plate of the sieve bin (10) are rotated 180 degrees to allow the aggregate to fall down, and the test is completed; The compressive strength of waste concrete in dry state can be calculated using formula (1); Where: σ is the compressive strength of waste concrete; F1 is the weight of waste concrete aggregate in a completely dry state; F3 is the force value when the displacement of the top plate (3) of the drying test bin reaches 30 mm; A is the cross-sectional area of ​​the aggregate bin; The softening coefficient of waste concrete can be calculated using formula (2); Where: K is the softening coefficient of waste concrete; F2 is the weight of waste concrete aggregate in a saturated state; F4 is the force value when the displacement of the top plate (13) of the saturated test bin reaches 30 mm; The crushing index of waste concrete in dry state can be calculated using formula (3); Wherein: δ is the crushing index of waste concrete; F5 is the force value of the bottom plate (10) of the sieve bin in the drying test bin (19).

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