A method for monitoring and repairing the interface health of a concrete structure

Abstract

The application discloses a concrete structure interface health monitoring and repairing method, and damage in-situ monitoring and repairing structure, which comprises a porous monitoring and repairing film placed at a specific concrete structure section. Two external copper foils or electrode pieces are arranged at two ends of the concrete structure section respectively, the internal porous monitoring and repairing film is connected with external electrical property measuring instruments of the concrete structure to form a sensing monitoring network, and the purpose of monitoring the internal micro-cracks of the concrete is achieved by monitoring the change of the electrical property of the film. The concrete repairing is realized by a microbial mineralization deposition method. The microbial nano-capsules are uniformly distributed in the internal porous film, or the porous monitoring and repairing film is directly used as a microbial carrier. When the concrete structure section is deformed or displaced due to external load, the concrete cracks at the film, the film is deformed or damaged, and the microbes in the film are released, so that the concrete structure crack repairing function is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a concrete damage repair device, in particular to a concrete structure interface health monitoring and repairing method. BACKGROUND

[0002] Concrete is widely used in civil engineering, harbor engineering and many other engineering fields due to its good durability, fire resistance, low maintenance cost, recyclability and large rigidity. However, during the service process of concrete structures, damage cracks, structure damage and performance degradation may occur due to external environmental corrosion and various loads borne by the structure. Early detection of damage can reduce the likelihood of major engineering accidents and reduce maintenance costs in the later stage of the project.

[0003] Therefore, health monitoring of important concrete structures has great engineering significance. Traditional concrete damage monitoring methods include surface observation, rebound hammer and optical fiber sensor. The traditional visual method can only see the cracks that have developed to a certain extent on the surface of the concrete structure, and cannot monitor the internal cracks of the concrete structure. The rebound hammer analyzes the strength of the concrete to evaluate the safety of the concrete structure, but cannot determine the exact location of the damage. The current mainstream monitoring methods have certain limitations and cannot identify and warn of cracks in the crack initiation and propagation stage.

[0004] In the traditional concrete health monitoring system, system identification of damage to damage repair requires a certain amount of time and labor cost. At present, the methods for repairing concrete cracks include structural reinforcement, appearance repair, crack grouting and the like. Although the above methods can achieve the function of crack repair, they have the disadvantages of high process requirement, complex operation, high cost and damage to the original structure of the concrete structure in actual use.

[0005] Based on the above, the present application provides a concrete structure interface health monitoring and repairing method to effectively solve the above problems. SUMMARY

[0006] In order to solve the problems in the background art, the present application provides a concrete structure interface health monitoring and repairing method.

[0007] The application adopts the technical scheme as follows: a concrete structure interface health monitoring and repairing method, comprising: a porous monitoring and repairing film, a concrete structure and the porous monitoring and repairing film being arranged at a concrete structure interface to be monitored, the porous monitoring and repairing film being consistent in shape with the concrete structure interface, the porous monitoring and repairing film being provided with a plurality of holes, and a microbial mineralization deposition method being used to repair the concrete structure; microbial colonies being wrapped with microbial capsules or being attached to the hole structure of the porous monitoring and repairing film, the microbial capsules being integrally formed with the porous monitoring and repairing film, and the microbial capsules being uniformly distributed in the porous monitoring and repairing film.

[0008] Further, the hole forming method of the porous monitoring and repairing film comprises salt / sugar templates, supercritical fluid foaming technology and laser drilling.

[0009] Further, the porous monitoring and repairing film is a combined structure film, comprising three layers, the lower layer and the upper layer being conductive monitoring layer films made of carbon nanotube / graphene and other conductive nanomaterials, the film substrate being polyurethane / polystyrene and other elastic materials, and the middle layer being a combined layer made of nanomaterials.

[0010] Further, the conductive monitoring layer film is divided into a plurality of conductive monitoring areas according to the monitoring needs of the concrete structure interface, so as to realize the function of accurate monitoring of the interface in different areas.

[0011] Further, the hole shape of the porous monitoring and repairing film is at least one of a circle, an ellipse, a square, a triangle and a rhombus, and the porosity is 15-35%. The ratio of the sum of the volumes of all the porous structures to the volume of the porous monitoring and repairing film is defined as V. In order to ensure the overall strength of the film, V≦0.5.

[0012] Further, the microorganism in the microbial capsule is one kind of mineralized microorganism or a mixed colony of a plurality of mineralized microorganisms.

[0013] Further, the microbial capsules or microbial colonies are mixed in the raw materials during the preparation of the porous monitoring and repairing film.

[0014] Further, the substrate material of the porous monitoring and repairing film is at least one of polyurethane / polystyrene elastic materials.

[0015] Further, the microbial colonies are single or multiple Bacillus microbial colonies, such as Paenibacillus popilliae, Paenibacillus cookii and Paenibacillus durus.

[0016] Further, the porous monitoring and repairing film adds nanoparticles to improve the interface performance of the conductive monitoring layer and the bonding layer, including but not limited to silicon dioxide nanoparticles.

[0017] Further, the porous monitoring and repairing film connects the damage monitor through the electrode sheet treated by the conductive silver paste.

[0018] Further, the porous monitoring and repairing film is connected with the electrical measuring instrument through a copper foil or an external electrode sheet, and the connection points around the film are multiple, divided into multiple monitoring channels to divide the interface of the concrete structure into multiple areas for monitoring, and the development of the interface cracks is monitored by observing the electrical signal data change of the porous monitoring and repairing film.

[0019] The film can be placed at a specific position to be monitored (fixed on a steel bar), so that the film is integrated with the concrete and vibrated and molded. The electrode is drawn out on the porous monitoring and repairing film for connection with the damage detector.

[0020] The electrode is connected with the damage detector, and the electrical signal change data of the porous monitoring and repairing film is monitored in real time.

[0021] When cracks occur at the interface between the porous monitoring and repairing film and the concrete structure due to the action of external loads, the porous monitoring and repairing film can deform cooperatively with the concrete structure, and the crack development of the upper and lower interfaces of the concrete structure can be reflected according to the different deformation amounts of the upper and lower conductive monitoring layers, and different degrees of mineralized microbial colonies are released to form calcium carbonate to repair the concrete cracks at the interface, thereby achieving the repairing effect.

[0022] The present application provides a concrete structure interface health monitoring and repairing method: a film that can deform with the concrete is prepared based on polyurethane / polystyrene elastic material. Since the film prepared from polyurethane / polystyrene elastic material can have a large deformation, the concrete structure has a large stiffness and can have a small deformation. In order to deform cooperatively with the concrete structure and strengthen the interface performance of the concrete structure and improve the interface toughness, the present application adds a nano-toughening material in the polyurethane / polystyrene elastic material, so as to improve the elastic modulus of the film, so that the monitoring film can deform cooperatively with the interface of the concrete structure, and the deformation and crack development of the concrete interface can be truly reflected. When cracks occur at the interface of the concrete structure, calcium carbonate produced by the mineralization reaction of the mineralized microorganisms in the porous monitoring and repairing film can suture the cracks of the interface of the concrete structure. The performance of the concrete repaired by multiple mineralized microorganisms can be restored to 90% of the initial undamaged state. This scheme greatly reduces the cost of monitoring the key concrete structure interface and maintaining the concrete structure later. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Flow chart for preparing the porous monitoring and repairing film of the present application;

[0024] Figure 2 Flow chart for preparing the porous monitoring and repairing film of the present application;

[0025] Figure 3 Structure schematic diagram of the porous monitoring and repairing film of the present application;

[0026] Figure 4 Structure schematic diagram of the porous monitoring and repairing film of the present application;

[0027] Figure 5 Structure schematic diagram of the porous monitoring and repairing film of the present application;

[0028] Figure 6 Mechanical performance test indexes of the porous monitoring and repairing film of the present application before and after monitoring and repairing the in-situ damage of the concrete structure.

[0029] The serial numbers in the figure represent, in order: 1-concrete structure, 2-porous monitoring and repairing film, 3-mineralized microbial colony, 4-in-situ damage monitor, 5-hole structure, 6-electrode sheet treated with conductive silver paste, 7-rigid pad and servo machine, and 8-precast type II concrete structure. DETAILED DESCRIPTION

[0030] The present application will be further described in detail below in combination with the drawings and specific embodiments.

[0031] In the drawings, the shape and size can be enlarged for clarity, and the same reference numerals will be used to indicate the same or similar parts in all the drawings.

[0032] Unless otherwise defined, technical terms or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms "first", "second", and similar terms do not imply any order, quantity, or importance, but are used to identify different components. Similarly, the terms "one", "a", or "the" do not limit the quantity to one but mean the presence of at least one. The terms "include", "comprise", and similar terms do not exclude other components or objects not listed. The terms "upper", "lower", "left", "right", and similar terms are used only to indicate relative positions, and may change accordingly when the absolute positions of the described objects change.

[0033] In the following description, terms such as center, thickness, height, length, front, back, rear, left, right, top, bottom, upper, lower, and the like are defined with respect to the configuration shown in the drawings, and in particular, "height" corresponds to the dimension from top to bottom, "width" corresponds to the dimension from left to right, and "depth" corresponds to the dimension from front to back, which are relative concepts and may change accordingly depending on the different positions and different use states, so these or other orientations should not be used to interpret as limiting terms.

[0034] Terms related to attachment, coupling, and the like (e.g., "connected" and "attached") refer to a direct or indirect fixed or attached relationship of the structures through intermediate structures, as well as movable or rigid attachment or relationship, unless otherwise explicitly stated.

[0035] The present application provides a concrete structure interface health monitoring and repair method. By arranging a porous monitoring and repair film at a specific interface of the concrete, a conductive sensing network is formed on the film using conductive nanomaterials such as carbon nanotubes / graphene. According to different interface characteristics and engineering actual conditions, multiple areas are divided to realize the function of real-time monitoring of multiple areas and multiple channels, and reduce the workload of processing invalid data by the system.

[0036] The present application utilizes the porous characteristics of the monitoring film to distribute mineralized microbial colonies in capsules on the film. When cracks occur in the concrete, the microbial colonies inside the film repair the cracks in the concrete through their own mineralization reaction. Using a variety of mixed microbial colonies to repair concrete cracks has higher robustness than using a single microbial colony to repair concrete cracks, and is suitable for a variety of service environments.

[0037] Reference Figure 1A flow chart for preparing the porous monitoring and repairing film is given. First, the acid-modified multi-walled carbon nanotubes (MWCNT) and polyurethane (TPU) particles are weighed according to the mixing ratio, and then added into a DMF solution. The solution is ultrasonically dispersed for 30 min by using an ultrasonic disperser to obtain a multi-walled carbon nanotube / polyurethane suspension.

[0038] Secondly, the suspensions with different contents of multi-walled carbon nanotubes are poured into a mold for solidification and molding. In order to strengthen the connection between the conductive monitoring layer and the bonding layer, the suspension for preparing the conductive monitoring layer film needs to be added with sio2 nanoparticles for dispersion again, and the content of multi-walled carbon nanotubes needs to be higher.

[0039] In order to make the conductive monitoring layer film as thin as possible, a silica gel flat plate is used as the mold. The thickness of the conductive monitoring layer film is measured to be 0.01 mm, and the thickness of the film of the bonding layer prepared by using a culture dish as the mold is 0.08 mm. The thickness of the final multi-layer structure combined film is controlled to be 0.1 mm.

[0040] With the increase of the content of multi-walled carbon nanotubes, the yield strength / breaking strength of the multi-walled carbon nanotube / polyurethane composite film increases, but the strain at the time of breaking decreases. In order to fully utilize the breaking strength of the multi-walled carbon nanotube / polyurethane film, the strain at the time of breaking of the conductive monitoring layer is controlled in the elastic stage of the bonding layer, which is convenient for the elastic deformation of the intermediate layer to restore the broken conductive monitoring layer to the original position and re-form the conductive path. At the same time, the nano-sized silicon dioxide particles in the interface will also help the conductive monitoring layer to restore to the original position.

[0041] The force holding layer is designed by laser drilling to obtain a porous film. The advantage of using the laser drilling method is that the hole parameters can be designed. Different from the salt / sugar template and carbon dioxide foaming methods used by other researchers to prepare porous films, the hole controllability of the laser drilling method is higher than that of these methods.

[0042] Figure 2 A process for preparing a porous structure film by using an environmentally friendly carbon dioxide foaming technology is given. By controlling the pressure and temperature, the size and density of the bubbles formed can be controlled.

[0043] Finally, a small amount of alcohol solution is sprayed on the inner surface of the conductive monitoring layer to wet it, and then the combination is pressed and compacted by using a press plate and heated to obtain a porous monitoring and repairing film.

[0044] Figure 3 The structure schematic diagram of the porous monitoring and repairing film with different hole shapes is given. Embodiment

[0045] Figure 4 As shown in the embodiment one of the present application, it can be seen that the in-situ monitoring and repairing system for the interface of concrete structure based on the porous monitoring and repairing film is composed of the following parts:

[0046] The porous monitoring and repairing film 2 is placed in the specific position to be monitored (it can be fixed on the steel bar) and is integrally formed with the concrete structure 1. At least one closed hole, semi-closed hole or through hole 5 is formed on the porous monitoring and repairing film for placing single or multiple mineralized microbial colony capsules 3.

[0047] The porous monitoring and repairing film draws out the electrode sheet 6 for externally connecting the in-situ damage monitor 4. The periphery of the porous monitoring and repairing film is treated by using conductive silver paste and is drop-cured and formed by using polyurethane / polystyrene elastic material to become the fixed terminal of the porous monitoring and repairing film. The porous monitoring and repairing film is connected with the in-situ damage monitor (such as the GILIT series products) by using external wires.

[0048] Further, the hole structure is at least one of circular, square and triangular shape. The ratio of the sum of the volumes of all the porous structures to the volume of the porous monitoring and repairing film is defined as V. In order to ensure the overall strength of the film, V≦0.5. In the present example, V=0.4, and in the Figure 3 The structure diagrams of the hole structure in the circular, square and triangular shape are given in the present example. Embodiment

[0049] Figure 5 As shown in the embodiment two of the present application, the difference between the embodiment two and the embodiment one is that:

[0050] Another in-situ monitoring and repairing system for the interface of concrete structure based on the porous monitoring and repairing film is disclosed, which is mainly aimed at the three-point bending load of the concrete structure and is composed of the following parts:

[0051] The porous monitoring and repairing film 2 is placed in the specific position to be monitored. In the present embodiment two, the porous monitoring and repairing film is placed at the prefabricated type II crack and is integrally formed with the concrete structure. At least one closed hole, semi-closed hole or through hole 5 is formed on the porous monitoring and repairing film for placing single or multiple mineralized microbial colony capsules 3.

[0052] The porous monitoring and repairing film draws out the electrode sheet 6 for externally connecting the in-situ damage monitor 4. The periphery of the porous monitoring and repairing film is treated by using conductive silver paste and is drop-cured and formed by using polyurethane / polystyrene elastic material to become the fixed terminal of the porous monitoring and repairing film. The porous monitoring and repairing film is connected with the in-situ damage monitor (such as the GILIT series products) by using external wires.

[0053] Further, the hole structure is at least one of a circle, a square, and a triangle; and a ratio of a sum of volumes of all the porous structures to a volume of the porous monitoring and repairing film is V. In order to ensure the overall strength of the film, V≦0.5. In the present example, V=0.4, and in Figure 3 The structural diagrams of the hole structure being a circle, a square, and a triangle are shown in

[0054] In the embodiment shown in Figure 5 The function of the in-situ monitoring and repairing system for the interface of the concrete structure based on the porous monitoring and repairing film provided in the present embodiment corresponds to the function achieved by the embodiment one, and therefore other functions of the present embodiment can be seen from the content in the embodiment one, which will not be described herein.

[0055] Concrete type II test:

[0056] The prefabricated type II crack concrete block prepared in the embodiment two is fixed to a 100T numerical control electro-hydraulic servo machine, and is ready for the type II fracture test, and a high-speed microscopic camera is used to record the video of the pulling process.

[0057] Before the type II fracture test starts, the Gilli 2700 and the porous monitoring and repairing film are connected in advance by external wires, and are tested. After the resistance value is stable within 30S, the type II fracture test is performed. The high-speed microscopic camera is aimed at the type II crack of the concrete, and the focal length is adjusted. The type II fracture test is started, and the displacement is controlled to realize the control of the loading amount of the concrete test piece.

[0058] When the high-speed camera finds that the type II crack of the concrete test piece expands by 0.2cm, the type II fracture test is stopped, the porous monitoring and repairing film is used to repair the type II expanding crack, the clamp is set to the initial position, the concrete test piece is pulled again, and the Gilli 2700 is started to monitor.

[0059] The load-displacement curve of the fiber pulling is shown in Figure 6 It is found through comparison that the mechanical performance index of the repaired concrete test piece can be restored to more than 90% of that before damage, and basically meets the purpose of reuse after repair. The data show that the repairing structure adopted in the embodiment two can achieve effective repair of the interface crack, and minimizes the maintenance cost of the concrete structure in the later period.

[0060] Because this monitoring and repair membrane is a composite membrane, the conductive channels of the upper and lower conductive monitoring layers are independent, allowing for separate monitoring of damage development at the upper and lower interfaces. The intermediate bonding layer possesses a certain degree of flexibility to ensure that the upper and lower conductive monitoring layers can deform independently. When the external load is a live load, the deformation occurring at the upper and lower interfaces of the concrete structure can be either shrinkage or stretching. The high elasticity of the intermediate bonding layer can cause the upper and lower conductive monitoring layers to shrink or stretch together. Even if the upper and lower conductive monitoring layers break due to excessive stretching deformation, they can still recover to their initial position thanks to the high elasticity of the intermediate bonding layer, forming a conductive monitoring path. Furthermore, this composite membrane utilizes at least one of the following hole-making processes: salt (sugar) template, environmentally friendly carbon dioxide foaming technology, and laser hole-making, to form a designable and controllable porous membrane structure.

[0061] Single or multiple mineralizing microbial colonies are arranged within the closed, semi-closed, or through-hole structures of porous structures. Among them, multiple mineralizing microbial colonies have higher adaptability to the environment. When the concrete structure is damaged by external loads, the porous monitoring and repair membrane will inevitably deform or rupture, thereby releasing the mineralizing microbial colonies within the porous monitoring and repair membrane to repair the interface cracks of the concrete structure. The mechanical properties of the repaired concrete structure can be restored to 90% of its initial state, which can basically meet the needs of subsequent engineering use and minimize the later maintenance and repair costs of the concrete structure.

[0062] The following is an explanation of the English parts in the image.

[0063] Figure 1 :

[0064] TPU particles: TPU particles; Slicone mold: silicone mold; SiO2 Nanoparticles: SiO2 nanoparticles

[0065] Adding SiO2 nanoparticles for ultrasonic dispersion:

[0066] conductive layer; Ultrasonic dispersion; culturedish.

[0067] Laser boring; the force layer; C2H6O spray.

[0068] Composite film: a composite film.

[0069] Figure 2 :

[0070] TPU particles: TPU granules; Ultrasonic dispersion: ultrasonic dispersion method; Foaming: foaming.

[0071] microcellular MWCNT / TPU composite film: microcellular MWCNT / TPU composite film.

[0072] Figure 3 :

[0073] Conductive monitoring layer; Microbial capsule.

[0074] Conglutinate layer; Combined; Circular holes.

[0075] Triangular holes: triangular holes

[0076] Figure 6 Pre-prosthetic: Before repair; After repair: After repair; Resistance increase: Increased strength.

[0077] Displacement: displacement; Load: load.

[0078] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for monitoring and repairing the health of concrete structure interfaces, characterized in that, include: A porous monitoring and repair membrane, a concrete structure, and the porous monitoring and repair membrane are disposed at the interface of the concrete structure to be monitored. The shape of the porous monitoring and repair membrane is consistent with the shape of the concrete interface to be monitored. The porous monitoring and repair membrane has multiple pores. The concrete structure is repaired by microbial mineralization deposition method. Microbial colonies are encapsulated in microbial capsules, which are uniformly distributed inside the porous monitoring and repair membrane, or the microbial colonies are attached to the pore structure of the porous monitoring and repair membrane. The microbial capsules and the porous monitoring and repair membrane are integrally formed. The porous monitoring and repair film is a composite structure film comprising three layers: the lower and upper layers are conductive monitoring layers made of carbon nanotube / graphene conductive nanomaterials; the film substrate is polyurethane / polystyrene elastic material; the middle layer is polyurethane / polystyrene elastic material; and nanomaterials are attached to its upper and lower surfaces. The conductive monitoring layer film is divided into multiple conductive monitoring areas according to the needs of concrete structure interface monitoring.

2. The method for monitoring and repairing the health of concrete structure interfaces as described in claim 1, characterized in that, The pore-forming method of the porous monitoring and repair film is a salt / sugar template, supercritical fluid foaming technology, or laser drilling; the pores are through holes, closed holes, or semi-closed holes.

3. The method for monitoring and repairing the health of concrete structure interfaces as described in claim 1, characterized in that, The porous monitoring and repair membrane has pores in at least one of the following shapes: circular, elliptical, square, triangular, and rhomboid, with a porosity of 15-35%.

4. The method for monitoring and repairing the health of concrete structure interfaces as described in claim 1, characterized in that, The microorganisms in the microbial capsule are one type of mineralizing microorganism or a mixed colony of multiple mineralizing microorganisms.

5. The method for monitoring and repairing the health of concrete structure interfaces as described in claim 1, characterized in that, When preparing pore monitoring and repair films, microbial capsules or microbial colonies are mixed into the raw materials and molded as a single unit.

6. The method for monitoring and repairing the health of concrete structure interfaces as described in claim 1, characterized in that, The porous monitoring and repair film substrate material is at least one of polyurethane / polystyrene elastic materials.

7. The method for monitoring and repairing the health of concrete structure interfaces as described in claim 1, characterized in that, The microbial colonies are single or multiple Bacillus microbial colonies.

8. The method for monitoring and repairing the health of concrete structure interfaces as described in claim 1, characterized in that, The porous monitoring and repair membrane is connected to an electrical measuring instrument via an external electrode plate. The membrane has multiple connection points around its perimeter, forming multiple monitoring channels to divide the concrete structure interface into multiple regions for monitoring. By observing the changes in the electrical signal data of the porous monitoring and repair membrane, the development of interface cracks can be monitored.

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