A method for preparing a stress self-sensing smart aggregate based on thick film resistance and a method for using the same

Abstract

The application relates to a preparation method and use method of stress self-sensing intelligent aggregate based on a thick film resistor, and belongs to the technical field of concrete sensors. The application aims to solve the problem of sensing and monitoring the stress state of concrete. The application comprises the following steps: preparing a high-temperature-resistant ceramic cubic substrate, the material of the high-temperature-resistant ceramic cubic substrate is aluminum oxide ceramic or fluorine mica glass sheet; sintering one thick film resistor sensor on the front surface and the back surface corresponding to the length and the height of the high-temperature-resistant ceramic cubic substrate respectively, and welding wires at the two ends of each thick film resistor sensor; coating a flexible protective layer with a thickness of 3-5 mm on the outer surface of the thick film resistor sensor, and penetrating the wires through the flexible protective layer for resistance collection; and coating an ultrahigh-performance concrete layer on the outer surface of the high-temperature-resistant ceramic cubic substrate containing the flexible protective layer and sintered with the thick film resistor, so as to obtain the stress self-sensing intelligent aggregate based on the thick film resistor. The application can realize real-time health monitoring.

Description

Technical Field

[0001] This invention belongs to the field of concrete sensor technology, specifically relating to a method for preparing and using a stress-sensing smart aggregate based on thick-film resistors. Background Technology

[0002] Real-time monitoring and diagnosis of the structural performance of major engineering structures, timely detection of structural damage, assessment of safety, prediction of performance changes and remaining lifespan, and decision-making for maintenance are of paramount importance for improving the operational efficiency of engineering structures and ensuring the safety of people's lives and property. This has become an increasingly urgent requirement in modern engineering. Developing concrete materials with self-sensing, self-response, and even self-repairing capabilities has become a major trend in the deep integration of modern technologies such as intelligent construction and smart buildings with the construction industry. Currently, there are two main approaches to achieving intelligent concrete. One is to embed sensing materials and devices such as fiber optic sensors and piezoelectric sensors within the concrete. This approach suffers from high costs, complex sensing systems, and difficult deployment. For example, a single measuring point of a fiber optic sensor costs at least several hundred yuan, and even the cheapest fiber optic demodulator costs tens of thousands of yuan. Piezoelectric ceramics can monitor the cracking process within concrete, but their embedding methods and signal demodulation are very complex, their principles are unclear, and the demodulation equipment is also very expensive. The other approach to achieving intelligence is to dope the concrete with a certain amount of conductive components, making the concrete a semiconductor state. Once the concrete is subjected to changes in stress, its resistance will also change. Analyzing changes in the stress state of concrete based on variations in its resistance has drawbacks. These include unstable resistance signals, poor linearity, and low accuracy. Summary of the Invention

[0003] The problem to be solved by this invention is to realize the perception and monitoring of the stress state of concrete, and to propose a method for preparing and using a stress-sensing smart aggregate based on thick film resistors.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing stress-sensing smart aggregate based on thick-film resistors includes the following steps:

[0006] S1. Prepare a high-temperature resistant ceramic cube substrate, wherein the material of the high-temperature resistant ceramic cube substrate is alumina ceramic or fluorophlogopite microcrystalline glass sheet;

[0007] S2. On the front and back sides corresponding to the length and height of the high-temperature resistant ceramic cube substrate, a thick film resistor sensor is sintered respectively, and wires are welded to both ends of each thick film resistor sensor.

[0008] S3. A flexible protective layer with a thickness of 3-5mm is wrapped around the outer surface of the thick film resistance sensor, and the wires penetrate the flexible protective layer to facilitate resistance acquisition.

[0009] S4. The high-temperature resistant ceramic cube with a flexible protective layer and sintered thick film resistor obtained in step S3 is coated with a layer of ultra-high performance concrete to obtain stress-sensing smart aggregate based on thick film resistor.

[0010] Furthermore, in step S1, the size range of the high-temperature resistant ceramic cubic substrate is [length range missing]. It is 5-10mm wide. 3-10mm, height The diameter is 20-30mm, and the material of the high-temperature resistant ceramic cube substrate is alumina ceramic or fluorophlogopite microcrystalline glass sheet.

[0011] Furthermore, in step S2, the thick film resistance sensor is sintered at the center of the face of the high-temperature resistant ceramic cube substrate.

[0012] Furthermore, the thick-film resistive sensor described in step S2 is prepared on a cubic substrate by screen printing and high-temperature sintering, with dimensions of [missing information]. Thick-film resistors containing electrodes.

[0013] Furthermore, in step S3, the flexible protective layer is made of soft silicone or polyurea high-elasticity waterproof sealant.

[0014] Furthermore, the dimensions of the ultra-high performance concrete encapsulated in step S4 are as follows: Hekuan The directional dimension is 20 to 40 mm, and the thickness in the vertical direction is... The thickness is 40 to 80 mm. The coating method involves embedding the high-temperature resistant ceramic cube with a flexible protective layer and sintered thick-film resistor obtained in step S3 into a length of [missing information]. Width Gao Wei The embedded position is at the very center of the mold. UHPC slurry is poured into the mold. During pouring, the wire is led out from the UHPC slurry. After molding for 1 day, the mold is demolded and placed in an accelerated curing chamber at 90°C for 2 days to obtain stress-sensing smart aggregate based on thick film resistor.

[0015] A method for using the stress-sensing smart aggregate based on thick-film resistor prepared by the aforementioned method includes the following steps:

[0016] Step 1. Calibrate the stress-sensing smart aggregate based on thick-film resistors by applying different loads F along the height direction.i Simultaneously, the resistance of the thick-film resistance sensor under the corresponding load is recorded; the average value R of the thick-film resistance sensor sintered on the two opposite sides of the cube's length and height is calculated. i This resistance value is named the intelligent aggregate resistor, where i represents the number of times different loads are applied, with a value ranging from 5 to 10.

[0017] Using the above data, the stress coefficient K is obtained through fitting:

[0018]

[0019] Where R0 is the resistance of the thick-film resistance sensor when the load is zero;

[0020] Step 2. The stress-sensing smart aggregate based on thick-film resistors, calibrated in Step 1, is embedded in the concrete. When the concrete is subjected to external loads, the resistance R of the smart aggregate is measured. t Calculate the stress F of the stress-sensing smart aggregate based on thick-film resistors. t The calculation formula is:

[0021] ;

[0022] Then, the stress of the stress-sensing smart aggregate based on thick-film resistors is calculated. The calculation formula is:

[0023] .

[0024] Furthermore, considering the additional stress influence between the measured stress of the embedded thick-film resistor-based stress-sensing smart aggregate and the measured stress of the concrete to be tested, according to the theory of embedded soil and rock pressure sensors, the matching error β is expressed as:

[0025]

[0026] Among them, P e P represents the additional stress; P is the real-time stress at the concrete measuring point; E s E represents the elastic modulus of stress-sensing smart aggregate based on thick-film resistors. c The elastic modulus of concrete; μ c The Poisson's ratio of the concrete;

[0027] Then the real-time stress at the concrete measuring point was calculated. , .

[0028] The beneficial effects of this invention are:

[0029] This invention discloses a method for preparing stress-sensing smart aggregate based on thick-film resistors. A fluorophlogopite microcrystalline glass sheet with a thick-film resistor sintered on its surface is embedded within a cement-based material to create concrete aggregate with dimensions similar to coarse aggregate. Since the resistance of the thick-film resistor sintered on the surface of the fluorophlogopite microcrystalline glass sheet changes with the deformation of the matrix, when the aggregate is under stress, it causes deformation of the internal fluorophlogopite microcrystalline glass sheet, resulting in a change in the thick-film resistance. Therefore, this aggregate can be embedded in concrete to achieve the sensing and monitoring of the concrete's stress state. Because fluorophlogopite microcrystalline glass is a ceramic-like material and the thick-film resistor is an inorganic material sintered at high temperatures, the entire sensing system is very stable. Furthermore, the resistance value of the thick-film resistor exhibits excellent linearity and stability with strain. Therefore, the main advantages of the smart aggregate encapsulated with this thick-film resistor fluorophlogopite microcrystalline glass sheet are good durability, wide operating temperature range, low creep, stable performance, and high cost-effectiveness. The aggregate prepared by this invention has higher precision than traditional smart aggregates with conductive materials added to cement paste; its price is lower than that of fiber optic sensors; and its durability is better than that of embedded strain gauges. The entire material is based on inorganic materials, exhibiting excellent resistance to extreme environments.

[0030] This invention achieves the sensing and monitoring of the stress state of concrete during its service life by pre-embedding thick-film resistive smart aggregates in concrete. Whether the target is the entire concrete structure or a single component, long-term monitoring of the same area is possible, and due to the good compatibility of the aggregates with concrete, it will not affect the normal use of the structure. A "resistance-load-stress" model is established by pre-embedding the thick-film resistive smart aggregates in the concrete. In the model, the stress and resistance value of the concrete are linearly related, so any measured resistance value has a unique corresponding stress. When the resistance value at a certain moment is input into the model, the stress value at that moment can be calculated. When the resistance values ​​at all times are input into the model, the stress values ​​of the concrete at all times can be calculated, achieving real-time monitoring of the stress state of the concrete. This invention provides a new approach to the health monitoring of concrete structures. By simply embedding the thick-film resistive smart aggregate sensors in important load-bearing locations during construction, the stress state at those locations can be monitored in real time and on-site. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a stress-sensing smart aggregate based on thick film resistors according to the present invention.

[0032] Figure 2 The calibration curves of a stress-sensing smart aggregate based on thick film resistors according to the present invention are shown in (a) and (b).

[0033] Figure 3 The sensing curves of a stress-sensing smart aggregate based on thick film resistors according to the present invention are shown in (a) and (b).

[0034] Figure 4 The resistance values ​​of the smart aggregate in concrete under different loads of the present invention are shown in (a) and (b) are the test curves of XT6-07 smart aggregate in concrete and XT6-08 smart aggregate in concrete.

[0035] Figure 5 This is a schematic diagram of the structure of the high-temperature resistant ceramic cube containing a flexible protective layer and sintered thick film resistor prepared in step S3 of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described specific embodiments are merely a part of the embodiments of the invention, and not all of them. The components of the specific embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations, and the invention may also have other embodiments.

[0037] Therefore, the following detailed description of specific embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected specific embodiments of the invention. All other specific embodiments obtained by those skilled in the art based on these specific embodiments without inventive effort are within the scope of protection of this invention.

[0038] To further understand the invention's content, features, and effects, the following specific embodiments are provided, along with accompanying drawings. Figure 1 - Appendix Figure 5 Detailed explanation is as follows:

[0039] Example 1:

[0040] A method for preparing stress-sensing smart aggregate based on thick-film resistors includes the following steps:

[0041] S1. Prepare a high-temperature resistant ceramic cube substrate, wherein the material of the high-temperature resistant ceramic cube substrate is alumina ceramic or fluorophlogopite microcrystalline glass sheet;

[0042] Furthermore, in step S1, the size range of the high-temperature resistant ceramic cubic substrate is [length range missing]. It is 5-10mm wide. 3-10mm, height The diameter is 20-30mm, and the material of the high-temperature resistant ceramic cube substrate is [material missing].

[0043] S2. On the front and back sides corresponding to the length and height of the high-temperature resistant ceramic cube substrate, a thick film resistor sensor is sintered respectively, and wires are welded to both ends of each thick film resistor sensor.

[0044] Furthermore, in step S2, the thick film resistance sensor is sintered at the center of the face of the high-temperature resistant ceramic cube substrate.

[0045] Furthermore, the thick-film resistive sensor described in step S2 is prepared on a cubic substrate by screen printing and high-temperature sintering, with dimensions of [missing information]. Thick-film resistors containing electrodes.

[0046] S3. A flexible protective layer with a thickness of 3-5mm is wrapped around the outer surface of the thick film resistance sensor, and the wires penetrate the flexible protective layer to facilitate resistance acquisition.

[0047] Furthermore, in step S3, the flexible protective layer is made of soft silicone or polyurea high-elasticity waterproof sealant.

[0048] Furthermore, in the long... ,Width ,high The microcrystalline glass cube is covered with a flexible protective layer with a thickness of 3 to 5 mm and a low elastic modulus along the vertical direction; the covering layer is 2 to 3 mm away from the top and bottom surfaces of the cube; the protective layer is used to protect the thick film resistor and make the stress form of the cube clear and singular, and the wires penetrate the covering layer to facilitate resistance acquisition.

[0049] S4. The high-temperature resistant ceramic cube with a flexible protective layer and sintered thick film resistor obtained in step S3 is coated with a layer of ultra-high performance concrete to obtain stress-sensing smart aggregate based on thick film resistor.

[0050] Furthermore, the dimensions of the ultra-high performance concrete encapsulated in step S4 are as follows: Hekuan The directional dimension is 20 to 40 mm, and the thickness in the vertical direction is... The thickness is 40 to 80 mm. The coating method involves embedding the high-temperature resistant ceramic cube with a flexible protective layer and sintered thick-film resistor obtained in step S3 into a length of [missing information]. Width Gao Wei The embedded position is at the very center of the mold. UHPC slurry is poured into the mold. During pouring, the wire is led out from the UHPC slurry. After molding for 1 day, the mold is demolded and placed in an accelerated curing chamber at 90°C for 2 days to obtain stress-sensing smart aggregate based on thick film resistor.

[0051] Furthermore, the wires penetrate the cladding layer to facilitate resistance measurement.

[0052] Furthermore, such as Figure 1 The smart aggregate based on thick-film resistors shown was loaded according to the following loading procedure, while its force value and the resistance value of the thick-film resistor were collected. The loading process is as follows: the load is gradually increased from 0 to 20 MPa, with each increment being 5 MPa, and the load is held for 30 seconds after each loading increment. Calibration curves for different smart aggregates are obtained as follows. Figure 2 and Figure 3 As shown in the figure. The above-mentioned smart aggregate was embedded in a C35 concrete test block with dimensions of 100*100*400 mm. Loading was performed according to the following procedure: the load was gradually increased from 0 to 25 MPa in increments of 5 MPa, and held for 30 seconds after each loading increment. Simultaneously, the resistance value of the smart aggregate embedded in the concrete was measured. The obtained curve is shown in the figure. Figure 4 As shown.

[0053] Furthermore, the initial resistance R0 of the sheet-type thick film resistor sensing element is 1000Ω to 20000Ω, preferably 5000Ω to 15000Ω; the initial resistance R0 does not correspond one-to-one with the overall size of the concrete component, but is determined based on the range of the data acquisition instrument, the monitoring sensitivity, the compressive cross-sectional area, and the calibration results.

[0054] Example 2:

[0055] The method for using the stress-sensing smart aggregate based on thick-film resistor prepared by the method described in Embodiment 1 includes the following steps:

[0056] Step 1. Calibrate the stress-sensing smart aggregate based on thick-film resistors by applying different loads F along the height direction. i Simultaneously, the resistance of the thick-film resistance sensor under the corresponding load is recorded; the average value R of the thick-film resistance sensor sintered on the two opposite sides of the cube's length and height is calculated. i This resistance value is named the intelligent aggregate resistor, where i represents the number of times different loads are applied, with a value ranging from 5 to 10.

[0057] Using the above data, the stress coefficient K is obtained through fitting:

[0058]

[0059] Where R0 is the resistance of the thick-film resistance sensor when the load is zero;

[0060] Step 2. The stress-sensing smart aggregate based on thick-film resistors, calibrated in Step 1, is embedded in the concrete. When the concrete is subjected to external loads, the resistance R of the smart aggregate is measured. t Calculate the stress F of the stress-sensing smart aggregate based on thick-film resistors. t The calculation formula is:

[0061]

[0062] Then, the stress of the stress-sensing smart aggregate based on thick-film resistors is calculated. The calculation formula is:

[0063] .

[0064] Furthermore, considering the additional stress influence between the measured stress of the embedded thick-film resistor-based stress-sensing smart aggregate and the measured stress of the concrete to be tested, according to the theory of embedded soil and rock pressure sensors, the matching error β is expressed as:

[0065]

[0066] Among them, P e P represents the additional stress; P is the real-time stress at the concrete measuring point; E s E represents the elastic modulus of stress-sensing smart aggregate based on thick-film resistors. c The elastic modulus of concrete; μ c The Poisson's ratio of the concrete; The length of the stress-sensing smart aggregate based on thick-film resistors; The width of the stress-sensing smart aggregate based on thick-film resistors; The height of stress-sensing smart aggregate based on thick film resistors;

[0067] Then the real-time stress at the concrete measuring point was calculated. : .

[0068] It should be noted that relational terms such as "first" and "second" are used merely 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 a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0069] Although this application has been described above with reference to specific embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of this application. In particular, as long as there is no structural conflict, the features in the specific embodiments disclosed in this application can be combined with each other in any way. The lack of an exhaustive description of these combinations in this specification is merely for the sake of brevity and resource conservation. Therefore, this application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing stress-sensing smart aggregate based on thick-film resistors, characterized in that, Includes the following steps: S1. Prepare a high-temperature resistant ceramic cube substrate, wherein the material of the high-temperature resistant ceramic cube substrate is alumina ceramic or fluorophlogopite microcrystalline glass sheet; S2. On the front and back sides corresponding to the length and height of the high-temperature resistant ceramic cube substrate, a thick film resistor sensor is sintered respectively, and wires are welded to both ends of each thick film resistor sensor. S3. A flexible protective layer with a thickness of 3-5mm is wrapped around the outer surface of the thick film resistance sensor, and the wires penetrate the flexible protective layer to facilitate resistance acquisition. S4. The high-temperature resistant ceramic cube with a flexible protective layer and sintered thick film resistor obtained in step S3 is coated with a layer of ultra-high performance concrete to obtain stress-sensing smart aggregate based on thick film resistor.

2. The method for preparing stress-sensing smart aggregate based on thick-film resistors according to claim 1, characterized in that, The size range of the high-temperature resistant ceramic cube substrate in step S1 is length. It is 5-10mm wide. 3-10mm, height The diameter is 20-30mm, and the material of the high-temperature resistant ceramic cube substrate is alumina ceramic or fluorophlogopite microcrystalline glass sheet.

3. The method for preparing stress-sensing smart aggregate based on thick-film resistors according to claim 2, characterized in that, In step S2, the thick film resistance sensor is sintered at the center of the surface of the high-temperature resistant ceramic cube substrate.

4. The method for preparing stress-sensing smart aggregate based on thick-film resistors according to claim 3, characterized in that, The thick-film resistive sensor described in step S2 is a material with dimensions of [missing information - likely a number], prepared on a high-temperature resistant ceramic cubic substrate by screen printing and high-temperature sintering. Thick-film resistors containing electrodes.

5. The method for preparing stress-sensing smart aggregate based on thick-film resistors according to claim 4, characterized in that, In step S3, the flexible protective layer is made of soft silicone or polyurea high-elasticity waterproof sealant.

6. The method for preparing stress-sensing smart aggregate based on thick-film resistors according to claim 5, characterized in that, The dimensions of the ultra-high performance concrete encapsulated in step S4 are as follows: Hekuan The directional dimension is 20 to 40 mm, and the thickness in the vertical direction is... The thickness is 40 to 80 mm. The coating method involves embedding the high-temperature resistant ceramic cube with a flexible protective layer and sintered thick-film resistor obtained in step S3 into a length of [missing information]. Width Gao Wei The embedded position is at the very center of the mold. UHPC slurry is poured into the mold. During pouring, the wire is led out from the UHPC slurry. After molding for 1 day, the mold is demolded and placed in an accelerated curing chamber at 90°C for 2 days to obtain stress-sensing smart aggregate based on thick film resistor.

7. A method for using the stress-sensing smart aggregate based on thick-film resistor prepared by the method for preparing stress-sensing smart aggregate based on thick-film resistor as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1. Calibrate the stress-sensing smart aggregate based on thick-film resistors by applying different loads F along the height direction. i Simultaneously, the resistance of the thick-film resistance sensor under the corresponding load is recorded; the average value R of the thick-film resistance sensor sintered on the two opposite sides of the cube's length and height is calculated. i This resistance value is named the intelligent aggregate resistor, where i represents the number of times different loads are applied, with a value ranging from 5 to 10. Using the above data, the stress coefficient K is obtained through fitting: Where R0 is the resistance of the thick-film resistance sensor when the load is zero; Step 2. The stress-sensing smart aggregate based on thick-film resistors, calibrated in Step 1, is embedded in the concrete. When the concrete is subjected to external loads, the resistance R of the smart aggregate is measured. t Calculate the stress F of the stress-sensing smart aggregate based on thick-film resistors. t The calculation formula is: ； Then, the stress of the stress-sensing smart aggregate based on thick-film resistors is calculated. The calculation formula is: 。 8. The method of using the stress-sensing smart aggregate based on thick-film resistor prepared by the method for preparing stress-sensing smart aggregate based on thick-film resistor according to claim 7, characterized in that, Considering the additional stress influence between the measured stress of the embedded thick-film resistor-based stress-sensing smart aggregate and the measured stress of the concrete to be tested, according to the theory of embedded soil and rock pressure sensors, the matching error β is expressed as: Among them, P e P represents the additional stress; P is the real-time stress at the concrete measuring point; E s E represents the elastic modulus of stress-sensing smart aggregate based on thick-film resistors. c The elastic modulus of concrete; μ c The Poisson's ratio of the concrete; Then the real-time stress at the concrete measuring point was calculated. , .

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