Microbial concrete in water-sand coupling crack self-repairing test device and method

Abstract

This invention discloses an experimental apparatus and method for self-healing cracks in microbial concrete under water-sand coupling, relating to the field of microbial concrete crack repair. The apparatus includes an experimental water tank, a specimen control and self-healing observation system, a water injection and drainage system, a water flow velocity control system, a sand content control system, and a water temperature control system. The experimental water tank is annular. The specimen control and self-healing observation system, the water injection and drainage system, the water flow velocity control system, the sand content control system, and the water temperature control system are all connected to the experimental water tank. The specimen control and self-healing observation system is located inside the straight section of the experimental water tank. This invention can construct the water-sand coupling environment required for the self-healing process of microbial concrete cracks, achieve automatic control of water flow velocity, sand content, and water temperature in the environment, adjust the angle between the concrete crack surface and the water flow direction, and facilitate more convenient observation of the crack self-healing effect.

Description

Technical Field

[0001] This invention relates to the field of microbial concrete crack repair, and more particularly to an experimental apparatus and method for self-healing cracks in microbial concrete under water-sand coupling. Background Technology

[0002] Microbial self-healing concrete is a novel intelligent concrete material. It is made by pre-embedding a microbial self-healing agent, including bacterial spores, inside the concrete. When the concrete is not cracked, the bacterial spores are in a dormant state inside the concrete. When the concrete cracks, external water and oxygen enter the cracks, activating the bacterial spores around the cracks. Utilizing the principle of MIP (Microbial Induced Carbonate Precipitate), the bacterial spores induce the production of CaCO3 crystals in the cracks, filling them and achieving self-healing.

[0003] Research findings indicate that the crack repair process of microbial self-healing concrete requires the participation of free water. Therefore, underwater curing is generally used in laboratories to conduct self-healing tests on microbial concrete cracks. When sand is present in the water, suspended silty sand particles can enter the cracks of the microbial self-healing concrete, acting as fillers while being cemented by the MIP reaction occurring within the cracks, thereby improving the repair effect of the microbial self-healing concrete. Therefore, microbial self-healing concrete has greater application prospects in water-sand environments. However, current experimental devices for microbial self-healing concrete mainly focus on controlling crack width. There is currently no suitable experimental device and method to detect the crack self-healing characteristics of microbial concrete in water-sand coupled environments, making it impossible to study the crack self-healing process under different flow velocities and sand concentrations. Summary of the Invention

[0004] The purpose of this invention is to provide a test device and method for self-healing cracks in microbial concrete in a water-sand coupling process, to construct the water-sand coupling environment required for the self-healing process of microbial concrete cracks, and to solve the problem of automatic control of water flow velocity, sand content and water temperature in the water-sand coupling environment.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] This invention discloses an experimental device for self-healing cracks in microbial concrete under water-sand coupling, comprising an experimental water tank, a specimen control and self-healing observation system, a water injection and drainage system, a water flow velocity control system, a sand content control system, and a water temperature control system. The experimental water tank is arranged in a ring shape. The specimen control and self-healing observation system, the water injection and drainage system, the water flow velocity control system, the sand content control system, and the water temperature control system are respectively connected to the experimental water tank. The specimen control and self-healing observation system is located in the straight section of the experimental water tank.

[0007] Preferably, the test water tank includes a top plate, a bottom plate, and a side plate connected as one piece. Angle steel brackets are fitted on both sides of the test water tank, and the angle steel brackets are fixed to the ground by bolts. A scale is provided on the side plate, and the test water tank is made of transparent plexiglass material.

[0008] Preferably, the specimen control and self-healing observation system includes a specimen clamping device and a specimen observation device. The specimen clamping device includes a base, a telescopic rod, and a specimen rotation system. The base is fixed to the base plate, and the top of the base is connected to the telescopic rod. The top of the telescopic rod is connected to the specimen rotation system. The specimen rotation system includes a bracket, a slide rail, and a specimen clamp. The back of the specimen clamp is connected to the top of the bracket via a rotating hinge. The slide rail is arc-shaped, and one end of the slide rail is fixed to the end of the back of the specimen clamp. A positioning pin is slidably connected inside the slide rail, and the other end of the slide rail is connected to the side of the bracket via the positioning pin.

[0009] The specimen observation device includes an observation lens, a movable link, and an external computer device. The end of the movable link is connected to the observation lens. The movable link and the observation lens extend into the interior of the test water tank. The movable link is electrically connected to the external computer device through a wire. The top plate has a specimen inlet and outlet.

[0010] Preferably, the specimen clamp holds the microbial self-healing concrete specimen, and the cracked surface of the microbial self-healing concrete specimen faces outward.

[0011] Preferably, the water injection and drainage system includes a water pump and a water tank outlet. The water inlet of the water pump is connected to an external water source, and the water outlet of the water pump is connected from the top plate of the test water tank to the interior. The water tank outlet is located at the bottom of the test water tank, and a valve is provided on the water tank outlet.

[0012] Preferably, the water flow velocity control system includes a flow rate controller, a flow meter, a flow actuator, and a flow stabilizer. The flow meter, the flow actuator, and the flow stabilizer are respectively disposed inside the test water tank. The flow meter is disposed directly in front of the microbial self-healing concrete specimen, the flow stabilizer is disposed in front of the flow meter, and the flow rate controller is disposed outside the test water tank. The flow meter and the flow actuator are electrically connected to the flow rate controller.

[0013] Preferably, the water flow actuator is configured as a propeller, and the flow stabilizer is a multi-pipe compact structure.

[0014] Preferably, the sand content control system includes a sand adding device and a vertical stirrer. The sand adding device includes a sand adding funnel and a horizontal stirrer. The bottom of the sand adding funnel extends through the top plate into the interior of the test water tank. The horizontal stirrer is installed on the bottom plate. The vertical stirrer extends into the interior of the test water tank and the top of the vertical stirrer is installed on the top plate.

[0015] The vertical mixer includes an electric robotic arm and a plastic broom. The top of the electric robotic arm is connected to a power source, and the bottom of the electric robotic arm is connected to the plastic broom.

[0016] Preferably, the water temperature control system includes a water temperature controller, a water thermometer, and a heater. The water thermometer and the heater are respectively installed on the top plate, and the bottom of the water thermometer and the bottom of the heater are respectively inserted into the liquid in the test water tank. The water temperature controller is installed outside the test water tank, and the water thermometer and the heater are electrically connected to the water temperature controller.

[0017] Experimental method using the above-described microbial concrete crack self-healing test device in water-sand coupling:

[0018] S1: Specimen arrangement: Place the precast microbial self-healing concrete specimen with cracks into the specimen clamp from the specimen inlet and outlet. Then loosen the positioning pins to allow the microbial self-healing concrete specimen and the slide rail to rotate around the rotating hinge until the cracked surface of the specimen reaches the angle required by the test conditions. Then tighten the positioning pins to fix the microbial self-healing concrete specimen in place. Adjust the telescopic rod to make the specimen reach a suitable height.

[0019] S2: Water injection. Close the valve at the outlet of the water tank, turn on the water pump to inject water into the test water tank, and read the water injection volume through the scale on the side plate. When the water injection volume reaches the set water volume V, turn off the water pump and the water injection stops.

[0020] S3: Set the flow rate. According to the test conditions, set the water flow rate of the flow rate controller to Q. At this time, the flow rate controller starts to control the water flow actuator to work, and the water in the test tank starts to flow. The flow meter monitors the water flow rate in real time and transmits the data to the flow rate controller. When the water flow rate reaches the design flow rate Q, the flow rate controller controls the rotation speed of the water flow actuator to keep the water flow in the tank at a constant flow rate Q.

[0021] S4: Adding sand. Based on the sand density η requirement in the test conditions, calculate the required sand mass m to be added to the water tank using Formula 1. Add sand of mass m to the water tank through a sand-adding funnel, while simultaneously turning on the horizontal and vertical agitators to ensure the sand is fully dispersed in the water and to prevent sedimentation. The calculation formula is as follows:

[0022] m = η·V,

[0023] In the formula, m is the mass of sand, η is the density of sand, and V is the volume of sand.

[0024] S5: Set the water temperature. Based on the water temperature requirements in the test conditions, set the temperature of the water temperature controller to T. At this time, the water thermometer transmits the water temperature in the test water tank to the water temperature controller. If the measured water temperature is lower than the designed water temperature T, the water temperature controller will control the heater to work and make the water temperature rise. When the water temperature reaches the designed water temperature T, the water temperature controller will control the heater to stop working. During the test, the water temperature will be monitored in real time to keep the water temperature at the designed water temperature T.

[0025] S6: Conduct the experiment. Once all test conditions meet the design requirements, begin the self-healing test of microbial concrete cracks. Daily, control the moving linkage via external computer equipment and observe the self-healing status of the cracks using an observation lens. Measure the crack width change during the test using the crack images obtained from the observation lens, and calculate the self-healing rate of the cracks. The calculation formula is as follows:

[0026]

[0027] In the formula, w is the crack self-healing rate, and D... i D is the initial crack width. f This represents the width of the crack after repair.

[0028] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0029] The present invention relates to a test apparatus and method for self-healing cracks in microbial concrete in a water-sand coupling environment. This apparatus can construct the water-sand coupling environment required for the self-healing process of microbial concrete cracks and achieve automatic control of water flow velocity, sand content and water temperature in the environment. At the same time, when conducting self-healing tests on microbial concrete cracks, the angle between the cracked surface of the concrete and the direction of water flow can be adjusted, making it more convenient to observe the self-healing effect of the cracks. Attached Figure Description

[0030] The present invention will be further described below with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the experimental device for self-healing cracks in microbial concrete in water-sand coupling according to the present invention;

[0032] Figure 2 This is a schematic diagram of the specimen control and self-healing observation system of the present invention;

[0033] Figure 3 This is a schematic diagram of the water injection and drainage system of the present invention;

[0034] Figure 4 This is a schematic diagram of the current stabilizer structure of the present invention;

[0035] Figure 5 This is a schematic diagram of the sand content control system of the present invention;

[0036] Figure 6 This is a schematic diagram of the water temperature control system of the present invention;

[0037] Figure 7 This is an image of the crack before repair in this invention;

[0038] Figure 8 This is an image of the crack after 28 days of repair according to the present invention.

[0039] Explanation of reference numerals in the attached drawings: 1. Test water tank; 1-1. Top plate; 1-2. Bottom plate; 1-3. Side plate; 1-4. Scale; 1-5. Angle steel bracket; 1-6. Bolt; 2. Specimen control and self-healing observation system; 2-1. Microbial self-healing concrete specimen; 2-2. Base; 2-3. Telescopic rod; 2-4. Slide rail; 2-5. Positioning pin; 2-6. Rotating hinge; 2-7. Specimen clamp; 2-8. Observation lens; 2-9. Movable connection 1. Rod; 2-10. External computer equipment; 2-11. Wire; 2-12. Specimen inlet / outlet; 3. Water pump; 4. Water tank outlet; 5. Flow rate controller; 6. Flow meter; 7. Water flow actuator; 8. Flow stabilizer; 9. Sand adding device; 9-1. Sand adding funnel; 9-2. Horizontal agitator; 10. Vertical agitator; 10-1. Electric robotic arm; 10-2. Plastic broom; 11. Water temperature controller; 12. Water thermometer; 13. Heater. Detailed Implementation

[0040] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] like Figure 1-8 As shown, a test device for self-healing cracks in microbial concrete under water-sand coupling includes a test water tank 1, a specimen control and self-healing observation system 2, a water injection and drainage system, a water flow velocity control system, a sand content control system, and a water temperature control system. The test water tank 1 is arranged in a ring shape. The specimen control and self-healing observation system 2, the water injection and drainage system, the water flow velocity control system, the sand content control system, and the water temperature control system are respectively connected to the test water tank 1. The specimen control and self-healing observation system 2 is set in the straight part of the test water tank 1 so that the specimen is in a stable water flow state during the test.

[0042] like Figure 3 As shown, the test water tank 1 includes a top plate 1-1, a bottom plate 1-2, and a side plate 1-3 connected as one piece. Angle steel brackets 1-5 are fitted on both sides of the test water tank 1. The angle steel brackets 1-5 are fixed to the ground by bolts 1-6 to ensure the stability of the water tank during the test. A scale 1-4 is provided on the side plate 1-3 to read the volume of water in the water tank. The test water tank 1 is made of transparent plexiglass material to facilitate observation of the test process in the water tank.

[0043] like Figure 2 As shown, the specimen control and self-healing observation system 2 includes a specimen clamping device and a specimen observation device. The specimen clamping device includes a base 2-2, a telescopic rod 2-3, and a specimen rotation system. The base 2-2 is fixed on the base plate 1-2. The top of the base 2-2 is connected to the telescopic rod 2-3, and the top of the telescopic rod 2-3 is connected to the specimen rotation system. The specimen rotation system includes a bracket, a slide rail 2-4, and a specimen clamp 2-7. The back of the specimen clamp 2-7 is rotated... The movable hinge 2-6 is connected to the top of the bracket. The slide rail 2-4 is arc-shaped. One end of the slide rail 2-4 is fixed to the end of the back of the specimen clamp 2-7. The slide rail 2-4 is slidably connected to the inside of the slide rail 2-4. The other end of the slide rail 2-4 is connected to the side of the bracket through the positioning pin 2-5. When the positioning pin 2-5 is loosened, the slide rail 2-4 is positioned and adjusted along the positioning pin 2-5, thereby realizing the angle between the crack surface and the water flow direction can be changed between 0° and 90°.

[0044] The specimen observation device includes an observation lens 2-8, a movable connecting rod 2-9, and an external computer device 2-10. The observation lens 2-8 is connected to the end of the movable connecting rod 2-9. The movable connecting rod 2-9 and the observation lens 2-8 extend into the interior of the test water tank 1. The movable connecting rod 2-9 is electrically connected to the external computer device 2-10 via a wire 2-11. A specimen inlet / outlet 2-12 is provided on the top plate 1-1. Specifically, the computer device can control the rotation of the movable connecting rod 2-9, thereby moving the observation lens 2-8 to the crack for observation. A scale is provided on the observation lens 2-8 to measure the width of the observed crack.

[0045] The specimen clamp 2-7 holds the microbial self-healing concrete specimen 2-1, and the cracked surface of the microbial self-healing concrete specimen 2-1 faces outward, fully contacting the water-sand coupling environment in the water tank.

[0046] like Figure 3 As shown, the water injection and drainage system includes a water pump 3 and a water tank outlet 4. The water inlet of the water pump 3 is connected to an external water source, and the water outlet of the water pump 3 is connected from the top plate 1-1 of the test water tank 1 to the interior. The water tank outlet 4 is located at the bottom of the test water tank 1, and a valve is provided on the water tank outlet 4.

[0047] like Figure 1 As shown, the water flow velocity control system includes a flow rate controller 5, a flow meter 6, a water flow actuator 7, and a flow stabilizer 8. The flow meter 6, the water flow actuator 7, and the flow stabilizer 8 are respectively disposed inside the test water tank 1. The flow meter 6 is disposed directly in front of the microbial self-healing concrete specimen 2-1, and the flow stabilizer 8 is disposed in front of the flow meter 6. The flow rate controller 5 is disposed outside the test water tank 1. The flow meter 6 and the water flow actuator 7 are electrically connected to the flow rate controller 5.

[0048] The water flow actuator 7 is configured as a propeller, and its rotation speed can be adjusted to regulate the water flow velocity in the test tank. Figure 4 As shown, the flow stabilizer 8 has a multi-pipe compact structure, which is used to make the water flowing through the concrete specimen as stable as possible.

[0049] like Figure 5As shown, the sand content control system includes a sand adding device 9 and a vertical stirrer 10. The sand adding device includes a sand adding funnel 9-1 and a horizontal stirrer 9-2. The bottom of the sand adding funnel 9-1 extends through the top plate 1-1 into the interior of the test water tank 1. The horizontal stirrer 9-2 is mounted on the bottom plate 1-2. The vertical stirrer 10 extends into the interior of the test water tank 1, and the top of the vertical stirrer 10 is mounted on the top plate 1-1. The sand adding funnel 9-1 is used to add sand to the water tank, and the horizontal stirrer 9-2 is used to stir the sand added to the water tank so that it can be fully dispersed in the water.

[0050] The vertical stirrer 10 includes an electric robotic arm 10-1 and a plastic broom 10-2. The top of the electric robotic arm 10-1 is connected to a power source, and the bottom of the electric robotic arm 10-1 is connected to the plastic broom 10-2. The electric robotic arm 10-1 can be agitated using an external power source, and the plastic broom 10-2 can move along with the electric robotic arm, sweeping up sand and soil deposited on the bottom plate 1-2 of the water tank. Specifically, the vertical stirrer 10 can be arranged at multiple points in the test water tank to achieve a better anti-sedimentation effect. In one specific embodiment, four sets of vertical stirrers 10 are evenly installed inside the arc-shaped section of the test water tank 1.

[0051] like Figure 6 As shown, the water temperature control system includes a water temperature controller 11, a water thermometer 12, and a heater 13. The water thermometer 12 and the heater 13 are respectively installed on the top plate 1-1, with the bottoms of the water thermometer 12 and the heater 13 extending into the liquid in the test water tank 1. The water temperature controller 11 is installed outside the test water tank 1, and the water thermometer 12 and the heater 13 are electrically connected to the water temperature controller 11. Specifically, the water thermometer 12 is placed near the microbial self-healing concrete specimen 2-1 to measure the water temperature in the tank and transmit the data to the water temperature controller 11. When the water temperature is lower than the set value, the water temperature controller 11 controls the heater 13 to work to raise the water temperature. When the water temperature reaches the set value, the water temperature controller 11 controls the heater 13 to stop working. Multiple heaters 13 can be set according to the size of the water tank.

[0052] Experimental method using the above-described microbial concrete crack self-healing test device in water-sand coupling:

[0053] S1: Specimen arrangement. Place the microbial self-healing concrete specimen 2-1 with a prefabricated crack into the specimen fixture 2-7 from the specimen entrance and exit 2-12. Then loosen the positioning pin 2-5 to rotate the microbial self-healing concrete specimen 2-1 and the slide rail 2-4 around the rotating hinge 2-6 until the cracking surface of the specimen reaches the angle required by the test conditions. After that, tighten the positioning pin 2-5 to fix the microbial self-healing concrete specimen 2-1 in place, and adjust the telescopic rod 2-3 to make the specimen reach a suitable height.

[0054] S2: Water injection. Close the valve at the outlet of the water tank 4, and turn on the water pump 3 to inject water into the test water tank 1. Read the injected water volume through the scale 1-4 on the side plate 1-3. When the injected water volume reaches the set water volume V, turn off the water pump 3 and the water injection stops.

[0055] S3: Set the flow rate. According to the requirements of the test conditions, set the water flow rate of the flow rate controller 5 to Q. At this time, the flow rate controller 5 starts to control the water flow pusher 7 to work, and the water in the test water tank 1 starts to flow. The flow meter 6 monitors the water flow rate in real time and transmits the data to the flow rate controller 5. When the water flow rate reaches the designed flow rate Q, the flow rate controller 5 controls the rotation speed of the water flow pusher 7 to keep the water flow in the water tank at a constant flow rate Q.

[0056] S4: Add sand. According to the requirement of the sand density η in the test conditions, use formula (1) to calculate the mass m of the sand and soil to be added to the water tank. Add the sand and soil with a mass of m to the water tank through the sand adding funnel 9-1. At the same time, turn on the horizontal stirrer 9-2 and the vertical stirrer 10 to fully disperse the sand and soil in the water and prevent sedimentation. The calculation formula is shown in formula (1):

[0057] m = η·V (1),

[0058] In the formula, m is the mass of the sand and soil, η is the density of the sand and soil, and V is the volume of the sand and soil.

[0059] S5: Set the water temperature. According to the requirement of the water temperature in the test conditions, set the temperature of the water temperature controller 11 to T. At this time, the water thermometer 12 transmits the water temperature in the test water tank to the water temperature controller 11. If the measured water temperature is lower than the designed water temperature T, the water temperature controller 11 will control the heater 13 to work to raise the water temperature. When the water temperature reaches the designed water temperature T, the water temperature controller 11 will control the heater 13 to stop working. During the test, the water temperature will be monitored in real time to keep the water temperature at the designed water temperature T.

[0060] S6: Conduct the experiment. Once all test conditions meet the design requirements, begin the self-healing test of microbial concrete cracks. Daily, control the movable linkage 2-9 via external computer equipment 2-10, and observe the self-healing status of the cracks using observation lens 2-8. Measure the crack width change during the test using the crack images obtained from observation lens 2-8, and calculate the self-healing rate of the cracks. The calculation formula is shown in Formula 2.

[0061]

[0062] In the formula, w is the crack self-healing rate, and D... i D is the initial crack width. f This represents the width of the crack after repair.

[0063] One example is the experimental design: the self-healing microbial concrete specimens were 40mm × 40mm × 160mm in size, with the cracked surface of the concrete specimens forming a 30° angle with the water flow direction. The water flow velocity was controlled at 1m / s, and the sand content in the water was controlled at 1kg / m³. 3 The water temperature was controlled at 30℃, and the experiment lasted for 28 days.

[0064] The specific implementation method of this experiment is as follows:

[0065] (1) Place the precast cracked microbial self-healing concrete specimen 2-1 from outlet 2-12 into specimen clamp 2-7, loosen positioning pin 2-5, and rotate specimen 2-1 and slide rail 2-4 around rotating hinge 2-6 until the cracked surface of the specimen forms a 30° angle with the water flow direction. Tighten positioning pin 2-5 to fix specimen 2-1 in place. Adjust telescopic rod 2-3 so that the height of specimen 2-1 is lower than the final water level.

[0066] (2) Close the valve at outlet 4 of the test water tank, and turn on water pump 3 to fill the water tank with water until the water level covers the specimen. Read the total water volume as 0.5 m³ using the scale 1-4 on the side plate 1-3 of the water tank. 3 Turn off the water pump.

[0067] (3) Set the water flow velocity of the flow meter 6 to 1 m / s. At this time, the flow controller 5 starts to control the water flow actuator 7 to work, and the water in the test tank begins to flow. The flow meter 6 will detect the water flow velocity in real time and transmit the data to the flow controller 5. After adjustment by the flow controller 5, the water flow velocity in the tank is finally maintained at 1 m / s.

[0068] (4) According to the experimental requirements, the sand content in the water should be controlled at 1 kg / m³. 3Using formula (1), the required mass of sand to be added to the water tank is 0.5 kg. Slowly add 0.5 kg of test sand to the water tank through sand adding funnel 9-1. Before adding, turn on horizontal mixer 9-2 and vertical mixer 10 to fully disperse the sand in the water and prevent sedimentation.

[0069] (5) Set the temperature of the water level controller 11 to 30℃. At this time, the water thermometer 12 transmits the water temperature in the test water tank to the water temperature controller 11. If the measured water temperature is lower than the design water temperature of 30℃, the water temperature controller 11 will control the heater 13 to work, so that the water temperature rises. When the water temperature reaches the design water temperature of 30℃, the water temperature controller 11 will control the heater 13 to stop working. During the test, the water temperature will be monitored in real time and dynamically adjusted in the above manner to keep the water temperature at the design water temperature of 30℃.

[0070] (6) Once all test conditions meet the design requirements, the self-healing test of microbial concrete cracks begins. Daily, the self-healing status of the cracks is observed using the observation lens 2-8, controlled by external computer equipment 2-10 and moving link 2-9. Crack images obtained using the observation lens 2-8 are shown below. Figure 7 As shown. The width change of the crack during the test was measured, and the self-healing rate of the crack was calculated using the formula shown in Formula (II). From Figure 7-8 As can be seen, the crack width was 0.76mm before repair, and after a 28-day self-healing process, the crack width was 0mm. Calculations show that the self-healing rate of the crack can reach 100%.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0072] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A microbial concrete in water-sand coupling crack self-repairing test device, characterized in that: The test water tank (1), specimen control and self-healing observation system (2), water injection and drainage system, water flow velocity control system, sand content control system and water temperature control system are included. The test water tank (1) is set as a ring. The specimen control and self-healing observation system (2), the water injection and drainage system, the water flow velocity control system, the sand content control system and the water temperature control system are respectively connected to the test water tank (1). The specimen control and self-healing observation system (2) is set inside the straight part of the test water tank (1). The test water tank (1) includes a top plate (1-1), a bottom plate (1-2), and a side plate (1-3) connected as one piece. The specimen control and self-healing observation system (2) includes a specimen clamping device and a specimen observation device. The specimen clamping device includes a base (2-2), a telescopic rod (2-3), and a specimen rotation system. The base (2-2) is fixed on the base plate (1-2). The top of the base (2-2) is connected to the telescopic rod (2-3). The top of the telescopic rod (2-3) is connected to the specimen rotation system. The specimen rotation system includes a bracket, a slide rail (2-4), and a specimen clamp (2-7). The back of the specimen clamp (2-7) is connected to the top of the bracket through a rotating hinge (2-6). The slide rail (2-4) is arc-shaped. One end of the slide rail (2-4) is fixed to the end of the back of the specimen clamp (2-7). A positioning pin (2-5) is slidably connected inside the slide rail (2-4). The other end of the slide rail (2-4) is connected to the side of the bracket through the positioning pin (2-5). The specimen observation device includes an observation lens (2-8), a movable connecting rod (2-9), and an external computer device (2-10). The end of the movable connecting rod (2-9) is connected to the observation lens (2-8). The movable connecting rod (2-9) and the observation lens (2-8) extend into the interior of the test water tank (1). The movable connecting rod (2-9) is electrically connected to the external computer device (2-10) through a wire (2-11). The top plate (1-1) has a specimen inlet / outlet (2-12). The sand content control system includes a sand adding device (9) and a vertical stirrer (10). The sand adding device includes a sand adding funnel (9-1) and a horizontal stirrer (9-2). The bottom of the sand adding funnel (9-1) extends through the top plate (1-1) into the interior of the test water tank (1). The horizontal stirrer (9-2) is installed on the bottom plate (1-2). The vertical stirrer (10) extends into the interior of the test water tank (1) and the top of the vertical stirrer (10) is installed on the top plate (1-1). The vertical mixer (10) includes an electric mechanical arm (10-1) and a plastic broom (10-2). The top of the electric mechanical arm (10-1) is connected to a power source, and the bottom of the electric mechanical arm (10-1) is connected to the plastic broom (10-2).

2. The microorganism concrete in water-sand coupling crack self-repairing test device according to claim 1, characterized in that: The test water tank (1) is fitted with angle steel brackets (1-5) on both sides. The angle steel brackets (1-5) are fixed to the ground by bolts (1-6). A scale (1-4) is provided on the side plate (1-3). The test water tank (1) is made of transparent organic glass material.

3. The experimental device for self-healing cracks in microbial concrete in water-sand coupling according to claim 2, characterized in that: The specimen clamp (2-7) holds the microbial self-healing concrete specimen (2-1), and the cracked surface of the microbial self-healing concrete specimen (2-1) faces outward.

4. The experimental device for self-healing cracks in microbial concrete in water-sand coupling according to claim 2, characterized in that: The water injection and drainage system includes a water pump (3) and a water tank outlet (4). The water inlet of the water pump (3) is connected to an external water source. The water outlet of the water pump (3) is connected from the top plate (1-1) of the test water tank (1) to the interior. The water tank outlet (4) is located at the bottom of the test water tank (1), and a valve is provided on the water tank outlet (4).

5. The experimental device for self-healing cracks in microbial concrete in water-sand coupling according to claim 3, characterized in that: The water flow velocity control system includes a flow rate controller (5), a flow meter (6), a water flow actuator (7), and a flow stabilizer (8). The flow meter (6), the water flow actuator (7), and the flow stabilizer (8) are respectively located inside the test water tank (1). The flow meter (6) is located directly in front of the microbial self-healing concrete specimen (2-1). The flow stabilizer (8) is located in front of the flow meter (6). The flow rate controller (5) is located outside the test water tank (1). The flow meter (6) and the water flow actuator (7) are electrically connected to the flow rate controller (5).

6. The experimental device for self-healing cracks in microbial concrete in water-sand coupling according to claim 5, characterized in that: The water flow actuator (7) is configured as a propeller, and the flow stabilizer (8) is a multi-pipe compact structure.

7. The experimental device for self-healing cracks in microbial concrete in water-sand coupling according to claim 2, characterized in that: The water temperature control system includes a water temperature controller (11), a water thermometer (12), and a heater (13). The water thermometer (12) and the heater (13) are respectively installed on the top plate (1-1), and the bottom of the water thermometer (12) and the bottom of the heater (13) are respectively inserted into the liquid in the test water tank (1). The water temperature controller (11) is installed outside the test water tank (1), and the water thermometer (12) and the heater (13) are electrically connected to the water temperature controller (11).

8. The experimental method of the microbial concrete crack self-healing test device in water-sand coupling according to any one of claims 1-7, characterized in that: S1: Specimen arrangement: Place the precast microbial self-healing concrete specimen (2-1) with precast cracks into the specimen clamp (2-7) through the specimen inlet (2-12). Then loosen the positioning pin (2-5) to allow the microbial self-healing concrete specimen (2-1) and the slide rail (2-4) to rotate around the rotating hinge (2-6) until the cracked surface of the specimen reaches the angle required by the test conditions. Then tighten the positioning pin (2-5) to fix the microbial self-healing concrete specimen (2-1) in place. Adjust the telescopic rod (2-3) to make the specimen reach a suitable height. S2: Water injection, close the valve of the water tank outlet (4), turn on the water pump (3) to inject water into the test water tank (1), read the water injection volume through the scale (1-4) on the side plate (1-3), and turn off the water pump (3) when the water injection volume reaches the set water volume V, and the water injection stops. S3: Set the flow rate. According to the test conditions, set the water flow rate of the flow rate controller (5) to Q. At this time, the flow rate controller (5) starts to control the water flow actuator (7) to work. The water in the test tank (1) starts to flow. The flow meter (6) monitors the water flow rate in real time and transmits the data to the flow rate controller (5). When the water flow rate reaches the design flow rate Q, the flow rate controller (5) controls the rotation speed of the water flow actuator (7) to keep the water flow in the tank at a constant flow rate Q. S4: Add sand. According to the requirements of sand density η in the test conditions, the mass m of sand to be added to the water tank is calculated using formula (I). The mass of sand m is added to the water tank through the sand adding funnel (9-1). At the same time, the horizontal agitator (9-2) and the vertical agitator (10) are turned on to fully disperse the sand in the water and prevent sedimentation. The calculation formula is shown in formula (I). V (one), In the formula, m is the mass of the sand. Let V be the density of the sand, and V be the volume of the sand. S5: Set the water temperature. According to the water temperature requirements in the test conditions, set the temperature of the water temperature controller (11) to T. At this time, the water temperature meter (12) transmits the water temperature in the test water tank to the water temperature controller (11). If the measured water temperature is lower than the designed water temperature T, the water temperature controller (11) will control the heater (13) to work and make the water temperature rise. When the water temperature reaches the designed water temperature T, the water temperature controller (11) will control the heater (13) to stop working. During the test, the water temperature will be monitored in real time so that the water temperature is kept at the designed water temperature T. S6: Conduct the experiment. Once all test conditions meet the design requirements, begin the self-healing test of microbial concrete cracks. Daily, control the moving link (2-9) using an external computer device (2-10) and observe the self-healing status of the cracks using an observation lens (2-8). Measure the crack width change during the test using the crack images obtained from the observation lens (2-8), and calculate the self-healing rate of the cracks. The calculation formula is shown in Formula 2. (two) where w is the crack self-repair rate, D i is the initial crack width, D f is the crack width after repair.

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