Microwave-based non-destructive testing device and method for measuring concrete strength

Abstract

The invention relates to a mobile device and measurement method developed to non-detructively measure the strength of concrete using electromagnetic (EM) waves in the microwave (MW) frequency band, which shows the resistance of the structure against earthquakes and external effects by measuring the strength of the concrete without damaging the reinforced concrete structure. The technical field of the invention is the non-destruuctive measurement of concrete strength using electromagnetic waves (EMW) in the microwave frequency band. This method is an alternative to destructive measurements by taking cores from structural elements such as columnsi beams, and slabs within the construction field, thus preventing damage to structures due to strength measurements and providing more rapid and non-destructive measurements from more regions. Results are evaluated using artificial intelligence techniques, providing a much more accurate strength measurement result instantly.

Description

[0001] DESCRIPTION

[0002] MICROWAVE-BASED NON-DESTRUCTIVE TESTING DEVICE AND METHOD FOR MEASURING CONCRETE STRENGTH

[0003] Technical Field

[0004] The invention relates to a mobile device and measurement method developed to non-detructively measure the strength of concrete using electromagnetic (EM) waves in the microwave (MW) frequency band, which shows the resistance of the structure against earthquakes and external effects by measuring the strength of the concrete without damaging the reinforced concrete structure. The technical field of the invention is the non-destruuctive measurement of concrete strength using electromagnetic waves (EMW) in the microwave frequency band. This method is an alternative to destructive measurements by taking cores from structural elements such as columnsi beams, and slabs within the construction field, thus preventing damage to structures due to strength measurements and providing more rapid and non-destructive measurements from more regions. Results are evaluated using artificial intelligence techniques, providing a much more accurate strength measurement result instantly.

[0005] Prior art

[0006] In the current state of the art, the method for measuring concrete strength involves drilling various parts of the concrete using a core machine and then analyzing the extracted samples in a laboratory. This process is time-consuming, labor-intensive, and expensive, leading to a minimal number of samples being taken to avoid excessive damage to the concrete structure. As a result, this approach does not provide reliable information about the overall condition of the structural element. Additionally, it is a method that not only takes a lot of time but also causes damage to the structure.

[0007] Contactless measurement methods, such as Ground Penetrating Radar (GPR), are also available. However, the signals used in GPR are only applied to the surface of the concrete, making it difficult to obtain reliable measurements in thick columns. Other non-destructive methods for measuring concrete strength include:

[0008] Penetration method

[0009] Rebound hammer method Pull out test method

[0010] • Ultrasonic pulse velocity method

[0011] • Radioactive methods

[0012] The closest patent to this invention is Zoughi Reza and Nowak Paul S's patent, identified as US 5939889 and dated August 17,1999, entitled "Strength-related testing of concrete using microwave signals." This patent describes a technique in which a MW oscillator signal is transmitted into the concrete via a directional coupler that mantains contact with the material. The reflected signal is subsequently received by a detector for analysis. The detected signals represent reflections of the microwave signals generated by the apparatus.

[0013] Another relevant patent is US10775332B2, belonging to Alizadeh Rouhollah; Ghods Pouria; Ghods Amir Hosein; Salehi Mustafa, and dated September 15, 2020 entitled "Electrical methods and systems for concrete testing," this patent describes the application of electrical currents to concrete for measurement purposes.

[0014] The Kruchowy Roman; Goff Dan; Smith Anthony's patent, numbered US5339023 and dated August 16, 1994, entitled "Nondestructive testing apparatus for determining the orientation of reinforcing bars within a concrete structure." This patent pertains to the measurement of reinforcing bar orientation within concrete structures.

[0015] Flesher Dann J; Becker David L; Beem William L; Berry Tommy C; Cannon N Scott's patent US 5592283A, entitled "Testing of concrete by laser ablation," involves the application of laser heating to concrete for testing purposes.

[0016] Additional pertinent patents include US 3468001A (Bodine, September 1969), US 6396265B1 (Shtalberg, May 2002), WO 2011130637 A2 (October 2011), and WO 2015172231 Al (November 2015). Upon examination, these patents will be recognized as distinct from the invention in question.

[0017] Examples of related studies are:

[0018] • "Determination of Concrete Quality in Buildings by Non-Destructive Geophysical Methods," SDU International Technological Science Constructional Technologies, Vol. 5, No. 2, December 2013, pp. 156- 165, Osman Uyamk, Guice §enli, Burak athoglu "Determination of Concrete Strength from Seismic Velocities," Osman Uyanik, SDU MF. Jeofizik Muh. Bol. Isparta, Jeofizik Bulteni, November 2012,

[0019] Aim of the Invention

[0020] The construction of buildings using concrete made from incorrect or insufficient materials, sometimes due to environmental conditions and their age, prevents them from being sufficiently resistant to external effects like earthquakes, which must be considered in their projects.

[0021] Therefore, the goal is to create a mobile, economical device that can measure concrete strength accurately, quickly, and without causing any damage to the structure, providing immediate results. Since this device can measure the concrete strength from many different points of the structure in a short time, rather than just a few spots, the resulting data will be much more realistic and accurate.

[0022] The structural and characteristic features of the invention, along with all its advantages, will be more clearly understood thanks to the detailed explanation written with references and attributions to the figures provided in the short description section of the invention. Therefore, the evaluation should be made considering these figures and the detailed explanation.

[0023] Detailed Description of the Invention

[0024] The figures pertaining to the invention are as follows:

[0025] Figure - 1 Schematic representation of the Non-Destructive Microwave Concrete Strength Measurement Device

[0026] The elements in the figures above are numbered as follows and will be used in the remainder of the description:

[0027] 1. Device for non-destructive measurement of concrete strength

[0028] 1.1. Antenna

[0029] 1.2. Dielectric material

[0030] 1.3. Cable assembly

[0031] 1.4. Case

[0032] 1.5. Microwave transceiver The invention relates to a measurement device(l) for non-destructive measurement and visualization of concrete strength using electromagnetic waves in the microwave band.

[0033] The method is based on the scattering of electromagnetic waves.

[0034] The essence of this method, known as scattering in electromagnetic wave theory, is based on the electromagnetic parameters, i.e. the conductivity, which are always constant, of the different layers that make up the closed environment in which the waves sent continuously from many places at different frequencies can penetrate, To ensure their scattering according to their dielectric permittivity and magnetic permeability "s(r), o(r), pO" and to analyze the data of the scattering materials in each scattered wave based on these scatterings with the same antennas and to display their type, size, shape and position.

[0035] The invention relates to a device for measuring concrete strength using microwaves(l), as described below and in the figures. It consists of a body containing receiver and transmitter antennas(l.l) and other modules, along with the other units that make up this device.

[0036] The antenna structure and setup required to measure electromagnetic parameters are designed to allow these waves to sufficiently penetrate the concrete block to be measured. Therefore, the outer casing of the antenna is coated with EMC (Electromagnetic compatible) material. Concrete has been modeled as a medium with electromagnetic parameters s(r), o(r), and pO. These parameters are called dielectric permittivity, conductivity, and magnetic permeability, respectively. pO is the magnetic permeability of a vacuum and is a known constant. Concrete can be used as the electromagnetic model of a non-homogeneous electromagnetic structure where dielectric permittivity and conductivity are functions of spatial coordinates. These parameters also vary with frequency, meaning they are functions of the microwave frequency.

[0037] For this purpose, the most accurate and detailed three-dimensional electromagnetic models should be created by applying standard formulas for various concrete samples. The goal in these models is to determine the most suitable frequency bands to be used, accurately identify the dielectric parameters of the matching environment that will surround the concrete, and ensure the correct design of the antenna(l.l). The results from simulation and test studies can be used to develop algorithms that benefit from a library created with concrete samples measured in as many different layers as possible.

[0038] Due to the large size of the antennas(l.l) used in the 500MHz-3GHz frequency band, the antennas(l.l) are covered with dielectric material(1.2) to reduce their size, leaving one end of the antennas(l.l) exposed. In an alternative use, to prevent damage to the dielectric material(1.2) and the antenna(l.l), the dielectric material is further covered with a case(1.4), preferably made of another dielectric material. In selecting the dielectric material, a material that matches the microwave impedance of the sample to be measured was preferred. Since the wavelength decreases in a high-dielectric environment, reducing the antenna(l.l) size, preferably two Vivaldi model, ultra-wideband antennas(l.l) have been placed. Additionally, this ensures that the electromagnetic waves radiated by the transmitting antenna (1.1) can penetrate as deeply as possible into the concrete and interact with all layers.

[0039] Supervised machine training techniques will be used to determine the concrete strength from the measured microwave scattering parameters. In this framework, the MPa strength values of the specimens previously tested for core strength and the scattering parameters measured against these specimens will be collected in a database to create training data for supervised machine learning models. After collecting a large number of measurement data, this data set will be converted into MPa values corresponding to concrete strength using different machine learning methods (Adaboost, xgboost, catboost, stochastic gradient descent, etc.) and ensemble learning regression models using multiple models using these methods. Similarly, to determine the concrete class (e.g., CIO, C20, C30, etc.), the same measurement data will be matched to the relevant concrete class using classification methods that employ supervised learning. Deep learning approaches as a sub-branch of machine learning (machine learning models using deep neural networks) will also be able to convert the measured data into MPa concrete strength.

[0040] As the device can quickly and without damage (without the need for coring) map the measured scattering parameters to concrete compressive strength in MPa, it can also be used fort he analysis of the structural strength of buildings. In this type of use, a large number of measurements to be taken at different points inside the building will be able to provide the necessary input for external simulation software to be used for structural analysis.

[0041] In the theoretical structure of the device (1) for measuring the strength of concrete with the help of microwave, the general structures of which are given above, there are the following main functions. Namely;

[0042] • High-resolution and noise-resistant imaging that can extract dielectric and conductivity coefficient changes using scattered field measurement data.

[0043] • Providing microwave measurements with the help of an electronic scanning system, antennas (1.1), antenna module, control, and measurement software by quickly and accurately generating the scattered electric field data that the imaging methods will use.

[0044] • A library of values for concrete strength created from a large number of previous concrete samples.

[0045] • An artificial intelligence-based decision mechanism that learns the library values and assists in imaging by comparing them with the measured values.

[0046] The device is designed as an end-product system, integrated with advanced imaging software.

[0047] There are basically three main approaches to scattering measurement: each method has its own advantages and disadvantages. The control unit of the inventive concrete strength measurement device(l) calculates the received data with these three methods and compares the results with library values and applies them to artificial intelligence to obtain results and reduce the error rate.

[0048] Microwave Measurement System

[0049] The microwave measurement used in the imaging systems of this invention operates as described: This system conducts scattering parameter measurements with up to two antennas (1.1). Ideally, this measurement can be performed using a two-port analyzer. Therefore, the system has been specially designed for the invention.

[0050] In the preliminary design evaluations of our system, the use of S parameter measurement modules was considered. The calibration step is extremely important for the microwave measurement system of the invention to perform measurements with acceptable accuracy. The calibration problem has been resolved in the proposed system architecture as follows:

[0051] In order for the system to produce highly accurate scattered field data, measurements are made using empty and conducting prism objects with known canonical geometric structures, respectively, and the results are compared and validated with simulation data, and measurement calibration coefficients are determined for each antenna(l.l) when necessary. Due to the antenna architecture, the 2 antennas(l.l) can measure S parameters in the lowest measurement time and the system can automatically calibrate itself.

[0052] Antennas(l): One of the most important components of the developed microwave measurement system is the antennas(l.l). Except for one end, the antennas(l.l) are covered with dielectric material(1.2). The exposed ends will be brought close to or contacted with the sample to be measured during the measurement process. Therefore, the surfaces not in contact with the sample are covered with dielectric material(1.2). To prevent damage to the dielectric material(1.2) and the antennas(l.l), the dielectric material(1.2) is again protected by a casing(1.4) over the dielectric material(1.2) so that the exposed ends of the antennas(l.l) are still exposed. The case(1.4) is also preferably made of dielectric material(1.2).

[0053] The very wide bandwidth and high gain(10MHz - 6GHz) of the antennas(l.l) are other important factors that determine their designs. Additionally, since the antennas(l.l) will radiate into the matching medium located between the concrete to be directly imaged and the case(1.4), the matching medium and the structure of the case(1.4) have also been considered in the designs. This approach is a significant advantage in achieving the small-sized antenna(l.l) structures mentioned above. Generally, Vivaldi antenna(l.l) structures have been prioritized in the designs.

[0054] In general terms, the device consists of the following elements.

[0055] A microwave transceiver(1.5) is a device that generates microwave energy in a specific frequency range. These devices generate signals at fixed or adjustable frequency, often used in test and measurement applications. Its purpose is to provide microwave signals of the desired frequency and power. Another task of the microwave transceiver(1.5) is to measure the incident, reflected and transmitted waves traveling along transmission lines. VNA (vector network analyzer) is preferably used as a microwave transceiver^.5).

[0056] SDR. (software defined radio) is used in alternative application.

[0057] Cable assembly(1.3) is used to transmit the frequency produced by the microwave transceiver^.5) to the antennas(l.l). RF cable is preferably used.

[0058] Antennas(l.l) to transmit microwave frequencies to the concrete sample.

[0059] The dielectric material(1.2) that surrounds the antenna(l.l) and helps to reduce the antenna size.

[0060] Case (1.4) that covers the dielectric material(1.2) to prevent damage to said dielectric material(1.2) and antennas(l.l).

[0061] In alternative embodiments of the invention, GPS (Global Positioning Service) is also included. In this way, the location of the measured location can be recorded in the measurement results.

[0062] In another alternative embodiment of the invention, an RF reader is added to the non-destructive concrete strength measurement device(l). In this way, if there is an RF Tag in the concrete sample to be measured, the RF reader can read the RF Tag information. The information on the RF Tag, such as when, by whom or by which company the concrete was poured, is read and reported, and the results of the comparison of the concrete parameters of the measured concrete are sent to the users and / or the central database.

[0063] For ergonomic use of the invention, all the above-mentioned elements are placed in a transportation bag. The transportation bag is open at one end. The surfaces of the antenna (1.1) not covered by the dielectric material (1.2) are protruded from this end. In this way, the user can go to the concrete sample to be measured with the carrying case and measure by placing the antennas (1.1) against the concrete.

Claims

CLAIMS1. A method for non-destructive measurement of concrete strength using microwaves, characterizing in that;At least one antenna(l.l) that will spread the microwaves produced by the microwave transceiver(1.5) towards the concrete sample to be measured; The microwave penetrating to a certain depth in said concrete sample and the microwave reflected and / or transmitted and / or scattered from the sample being received by said antennas(l.l);The received microwave being measured with the microwave transceiver(1.5);Involves the process steps of comparing the measured microwave value with the previously established concrete strength value and / or class from the microwave frequency database, and determining the concrete strength value and / or class.

2. A method for non-destructive measurement of concrete strength using microwaves suitable to Claim 1, characterizing in that;Involves the process step of recording the measured concrete strength value and / or class of each sample determined said database.

3. A method for non-destructive measurement of concrete strength using microwaves suitable to Claim 1, characterizing in that;Includes the process step of converting the said measurements into concrete strength values in MPa (megapascal) using regression-based and / or classification-based supervised machine learning methods.

4. A method for non-destructive measurement of concrete strength using microwaves suitable to Claim 1, characterizing in that;Includes the process step of matching these measurements to concrete classes using regression-based and / or classification-based supervised machine learning methods.

5. A method for non-destructive measurement of concrete strength using microwaves suitable to Claim 1, characterizing in that;Includes the process step of evaluating the said measurements in terms of statistical properties and providing information about the structural properties of the reiforcements in the concrete.

6. A method for non-destructive measurement of concrete strength using microwaves suitable to Claim 1, characterizing in that;Said measurements include the process step of making a holistic evaluation of the structure by evaluating the sample together with all other structural measurements of the structure if the sample is found in a structure.

7. A microwave non-destructive measuring device(l) for the strength of concrete; characterizing in that; at least one microwave transceiver(1.5) that measures, analyzes, monitors the microwave sprectra reflected and / or transmitted and / or scattered from the sample, and produces the microwave to transmitted to the sample,At least two receiver and / or transmitter antennas(l.l) that enable microwave broadcasting to the concrete sample to be measured,A dielectric material(1.2) that covers all surfaces of the antennas(l.l) except the surface from which microwave radiation is emitted towards the sample to be measured and ensures microwave impedance matching with the sample to be measured,Said microwave transceiver(1.5) comprises at least one database with concrete strength value and / or class data corresponding to the microwave frequencies, which enables the measurements to be converted into concrete strength values and / or classes.

8. A microwave non-destructive measuring device(l) for the strength of concrete; suitable to Claim 7, characterizing in that;- Said he microwave transceiver^.5) is a vector network analyzer (VNA).

9. A microwave non-destructive measuring device(l) for the strength of concrete; suitable to Claim 7, characterizing in that;Said microwave transceiver(1.5) is of the software-based radio network (SDR.) type.

10. A microwave non-destructive measuring device(l) for the strength of concrete; suitable to Claim 7, characterizing in that;The bandwidth of said antennas(l.l) are 10MHz - 6GHz.

11. A microwave non-destructive measuring device(l) for the strength of concrete; suitable to Claim 7, characterizing in that;Said antennas(l.l) are of the vivaldi type.

12. A microwave non-destructive measuring device(l) for the strength of concrete; suitable to Claim 7, characterizing in that;Said antennas(l.l) are microstrip.

13. A microwave non-destructive measuring device(l) for the strength of concrete; suitable to Claim 7, characterizing in that;All the elements mentioned are positioned in a carrying case.

14. A microwave non-destructive measuring device(l) for the strength of concrete; suitable to Claim 13, characterizing in that;- The surfaces of said antennas(l.l) which are not covered with dielectric material(1.2) are outside said carrying case.

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