• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
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    • 专利摘要:
    Electrical resistivity sensor integrated in concrete structures for the measurement of reinforcement corrosión, characterized by being connected to the steel reinforcement of the concrete (11) by earthing (5) and embedded in the concrete after concreting, consisting of a power source (8) and a device for measuring the voltage and current intensity (9); said resistivity sensor is formed by two cylindrical electrodes made of steel discs (1) and disks of polymeric insulating material (2), which are alternately arranged in layers fixed by a system of connection between discs (6) by means of thread or adhesive and mounted on a rectangular support for fixing the electrodes (7) with a distance established between electrodes of 5 cm. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2593960A1
    申请号:ES201530811
    申请日:2015-06-10
    公开日:2016-12-14
    发明作者:Juan Miguel MENESES RODRÍGUEZ；Francisco GIRALDO PAVÓN；María Luisa CARMONA CARMONA；María Isabel MOTA LÓPEZ；Basilio VALLEJO JIMÉNEZ
    申请人:Inst Tecnologico De Mat De Construccion Y Rocas Ornamentales；Instituto Tecnologico De Materiales De Construccion Y Rocas Ornamentales；
    IPC主号:
    专利说明:

    ELECTRICAL RESISTIVITY SENSOR INTEGRATED IN CONCRETE STRUCTURES FOR ARMOR CORROSION MEASUREMENT SECTOR OF THE TECHNIQUE
     Corrosion detection in steel reinforcements, by means of sensors integrated in concrete structures and attached to the reinforcement, on those that carry out resistivity measurements.
     Estimation of the corrosion rate of steel, from direct measurements of resistivity, with sensors attached to steel and integrated in hardened concrete.
    The present invention has civil construction as its scope, especially with regard to the infrastructure sector made of reinforced concrete. Concrete is the most frequently used construction material in all types of structures: houses, bridges, roads, dams, ditches, etc. The steel armor that these structures contain, can remain exempt
    20 corrosion indefinitely, except when the concrete is in contact with potentially aggressive environmental substances such as chlorides or atmospheric carbon dioxide itself. When the metal reinforcement corrodes, the formation of fissures takes place, accompanied by a loss of physical integrity and acceleration of the degradation of the concrete, which can compromise the safety of
    25 the structure. Currently, the high number of civil infrastructure of reinforced concrete makes it necessary to have a tool that allows real-time monitoring of the state of the same. For this reason, the number of integral monitoring systems of the unique reinforced concrete structures is increasing. Said monitoring includes the use of measurement sensors
    30 physical, combined with electrochemical type sensors, which provide real and accurate in-situ information of the steel structure of the concrete. On the other hand, the need to quantify the durability of concrete has led to the search for properties capable of quantifying all phases of the process, from the manufacture of concrete, to its curing and hardening. In this sense, the resistivity
    35 electrical is a property of concrete that allows its control in a non-destructive way, it also constitutes a powerful indicator of parameters such as setting, mechanical strength, degree of saturation of concrete, impermeability or resistance to the entry of aggressive substances in the concrete , which have a direct relationship with the corrosion rate of steel. The techniques
    5 used for its measurement are non-destructive, easy to apply, low cost and quick to respond. Therefore, resistivity is a parameter that allows the microstructure to be related to the durable behavior of concrete, both during the initiation period and the propagation of corrosion of steel. 10 BACKGROUND OF THE INVENTION
    Corrosion of the reinforcements is one of the main causes that affect the durability of the structures and their useful life. The carbonation of concrete and the action of aggressive ions, mainly chlorides, are the processes that most
    15 risk pose for corrosion of reinforcements. Corrosion of electrochemical type, involves the oxidation of a metal with the loss of mass equivalent to the amount of electrical charges that have circulated through its surface when the electrical circuit closes through the electrolyte that surrounds it.
    20 The diagnosis and monitoring of corrosion of concrete reinforcement is usually carried out with the application of invasive methodologies and techniques. Within this group are gravimetric methods, in which mass determinations are made during different time intervals. This method allows to obtain an integral value of corrosion, during a determined period of time. Unfortunately these
    25 procedures cannot always be carried out, since they entail the partial destruction of the structure, although they are suitable for the study of corrosion in the laboratory. On the other hand, there are alternative methods where the invasion of the structure can be minimal. These include the use of electrochemical techniques, which provide instantaneous measurement values. The application of this type of
    30 techniques is essential if you want to carry out a thorough control and monitoring of the structure, at any time for long periods of time.
    This type of electrochemical techniques are based on the imposition of a disturbance or application of a small electrical signal on the armor itself, 35 measuring the response that it causes to the system under study. Its advantage lies in the speed with which determinations can be made. The measurement of the current and voltage variables obtained by means of some electrochemical technique, allows the evaluation of corrosion parameters such as corrosion potential, corrosion rate and concrete resistivity. These parameters determine information about the coating, passivity and tendency to pit steel; as well as other information of interest. Authors such as C. Andrade and other authors have thoroughly investigated in recent years the possibilities of these techniques to predict durability, based on indicators obtained through the application of advanced electrochemical techniques, based on the application of measurement methods in -if you
    10 non-destructive, without direct contact with the reinforcement and directed externally on the concrete surface. However, currently the introduction of small sensors inside the concrete, usually during its implementation, is one of the most promising developments to control the long-term behavior of structures.
    15 For a few years, the measure of the resistivity in concrete has become an indicator of its durability, which provides information about setting, mechanical strength, degree of saturation and impermeability or resistance to the entry of aggressive substances into the concrete. It is a parameter that depends on the
    20 mobility, diffusion and concentration of free ions in solution, located in the pores of the concrete. That is, the resistivity is a property that reflects the capacity of the porous medium, to transport the electric charge, in a certain volume contained in the pores of the concrete structure.
    25 For the measurement of the resistivity, an electric field must be applied on the electric charges of the ions dissolved in the aqueous phase, contained in the pores of the concrete. The generated current is conducted through the network of pores interconnected by the movement of the ions. The diffusion of the ions, is a parameter dependent on the temperature and humidity existing in the pores, therefore
    30 it is always convenient to carry out the resistivity measurement with the appropriate degree of humidity.
    The versatility of the resistivity measures lies in its variability with respect to the degree of concrete saturation, curing time, transport or resistance to
    35 entry of aggressive substances. In addition, and in relation to the proposed invention,
    the measurement of the electrical resistivity allows its application for the interpretation of the value of the corrosion rate of the reinforcement, because the degree of saturation of the concrete influences its electrical resistivity and the availability of oxygen through the reinforcement; Both elements, humidity and oxygen, are essential for active corrosion processes to take place. Authors such as Alonso and collaborators managed to find a relationship between the measure of electrical resistance and the intensity of corrosion that allows to calculate the direct relationship between the resistivity itself and the intensity of corrosion. This has allowed over time, the establishment of different resistivity ranges in relation to the probability of corrosion, which are currently applied to studies of existing structures. It is generally accepted that a resistivity greater than 100-200 k · cm indicates a low risk of corrosion in the reinforcements, while values less than 10 k · cm represent a high probability of risk. In these cases, the intensity of corrosion, presents the upper level of the corrosion rate of the concrete structure
    15 studied.
    The resistivity measurement is performed using direct or indirect measurement methods, applied on the hardened concrete. The direct method is regulated by the UNE 83988-1: 2008 standard. In this, the resistivity is determined by applying a uniform electric field between two electrodes. The indirect method or method of Werner, consists in the application of a four-pointed electrode, also called Wenner resistivimeter. This method, regulated by the UNE 83988-2 standard, provides the electrical resistance of the concrete knowing the distance between the electrodes and the dimensions of the sample. Consists of the
    25 application of a current between two electrodes, located in the generatrix of the specimen, after which the voltage is measured on two other electrodes, located between the previous ones and aligned with them.
    Both methods must be performed with cylindrical or prismatic specimens that are
    30 manufactured according to the UNE-EN 12390-2 standard from fresh concrete obtained on site, or extracted directly from the concrete structure, as a witness as specified in the UNE-EN 12504-1 standard. In both cases, the specimens, regardless of the method used in their manufacture, must have a minimum height of 200 mm, can not contain armor inside and must be saturated
    35 previously in water in the laboratory. The characteristics of conventional resistivity measurement procedures present a series of drawbacks such as a partial destruction of the structure. All this makes the measurement conditions not real, with respect to those presented by the structure at any time during its useful life.
    5 To address these inconveniences, the introduction of small sensors inside the concrete at the time of its manufacture is one of the most promising developments to control the long-term behavior of the structures. These electrodes can report the presence of moisture and the
    10 evolution of corrosion potential. At this point, the present invention describes a new type of electrochemical sensor embedded in the concrete, in permanent direct contact with the reinforcement, within the structure and carrying out continuous resistivity measurements over time.
    15 Different authors have used embedded sensors for measurements of corrosion and resistivity potential, formed by different reference electrodes that can be made of titanium, Mn / MnO2, silver and lead, together with stainless steel measuring electrodes for the measurement of resistivity. However, these types of sensors have been designed to be installed directly on the concrete surface.
    20 Recently, other authors have published the design of a compact embedded multisensor capable of measuring different parameters on the same sensor. In this type of sensor, a Wenner resistivity meter of small size stands out. The present invention therefore proposes a new sensor embedded in concrete, based on the direct method of resistivity consisting of two electrodes separated by
    25 a certain distance between the two, unlike the four employees in the Wenner method. EXPLANATION OF THE INVENTION
    The present invention relates to an electrical resistivity sensor integrated in concrete structures, which has been designed for the measurement of corrosion and corrosion rate of reinforcements. The sensor constitutes a device which is attached to the reinforcement and subsequently integrated into the concrete structure, after the concreting process. The sensor attached to the steel frame is integrated and
    35 fixed in the structure after the setting of the concrete. This type of sensor allows the diagnosis of the state of corrosion of the steel in the concrete structure at zero time and during its life, constituting a non-destructive method, which achieves great precision and accuracy in the measurement .
    5 The sensor consists of two similar electrodes, formed by superimposed discs of different material. Both electrodes are manufactured by two stainless steel discs, which are alternately arranged between discs of a material of an insulating nature, of identical diameter to the steel discs, whose function is to favor electrical insulation between two steel discs
    10 belonging to the same electrode. In working situation, both electrodes are arranged parallel to a horizontal support attached to it by its base and separated both from each other by a known distance.
    The advantage of this type of sensor is that it is integrated into the structure
    15 concrete ensures full contact of the steel discs as they are completely surrounded by a layer of concrete around and between the two electrodes, at a separation distance of 5-8 cm.
    The arrangement and thickness of each of the disks that make up the sensor, makes
    20 that the steel discs be at different heights; This allows simultaneous resistance values to be obtained depending on the depth of the concrete. However, to obtain a control of the resistivity as a function of the actual depth of the measurement, it is necessary to know the depth at which both electrodes are introduced parallel to the surface of the concrete. This allows to avoid lags
    25 in height between the position of each steel disk in relation to the concrete covering and the steel reinforcement of the structure.
    The current data between both electrodes, as well as the potential difference established between the two can be collected through a control system
    30 digital and conventional data acquisition. Due to the characteristics described, this type of sensor has the advantage of being able to collect data from the structure under study, at any time and place, without the need for it to be in situ.
    BRIEF DESCRIPTION OF THE DRAWINGS
    To complement the description that is being made and in order to help abetter understanding of the features of the invention, is accompanied as part5 member of said description, a set of drawings where illustrative andnon-limiting, the following has been represented:
    Figure 1. Shows a general and schematic perspective view of a sensor electrode as described in the description and used in the method of
    10 measure of the resistivity of concrete structures. Also the same figure shows the measurements of each of the pieces that compose it for its manufacture
    Figure 2. Shows a schematic representation of the perspective side section of the same sensor electrode, in which the detail can be seen.
    15 arrangement of each of the necessary electrical components and connections that make it up.
    Figure 3. Shows an external side elevation of an electrode showing the arrangement of the material used for joining the different components of the
    20 same.
    Figure 4. Shows in perspective the complete sensor in working situation, that is, with the electrodes properly adapted to the concrete structure under analysis and connected to the potential source, which generates the electric field
    25 required, and the measuring device on which the measurements taken are collected
    Below is a list of the different elements represented in the figures that make up the invention:
    30 (1) Steel discs
    (2) Discs of insulating polymeric material
    (3) Electric connections
    (4) Center hole
    (5) Grounding 35 (6) Disc joining system
    (7) Rectangular support for electrode fixation
    (8) Power supply
    (9) Device for measuring voltage and current intensity
    (10) Welding point in the armor5 (11) Steel concrete armor PREFERRED EMBODIMENT OF THE INVENTION
    In order to achieve a better understanding of the invention, the manufacturing process according to the following embodiment will be described below:
    The resistivity sensor described in the present invention, is formed by two identical electrodes so both must be manufactured following the same procedure. The manufacture of the electrode is carried out by assembling
    15 steel discs (1) of 3 cm in diameter and 0.5 cm thick, and discs of rigid insulating polymeric material (2) of equal diameter to those of steels and 1 cm thick.
    Each disk has a central hole (4) through which different
    20 electrical connections (3) with each steel disk (1); either by soldering tin or other suitable joint. These connections must ensure the correct application of the electric field between both electrodes and the adequate recording of current intensity readings and the potential difference from the sensor to the voltage and current intensity measuring device (9), after application. of the
    25 electric field with power supply (8). At the same time, each electrode will have an earth connection (5) that is connected directly to the steel reinforcement of the concrete (11) before the start-up of the power supply (8). For the assembly and fixation of the electrode parts, a joint system between discs (6) by means of thread or adhesive will be used.
    30 Finally, the electrodes that make up the sensor must be fixed to a rectangular support for fixing the electrodes (7) separated from each other at a distance of 8 cm, counting from the center of each electrode. The support must be made of a material that does not have electrical conductivity phenomena, and chemically
    35 stable so as not to degrade inside the concrete, that is, it must be resistant to a basic pH between approximately 12.5-14.0. As a material suggestion for the support of both electrodes, 1.0-1.5 cm thick methacrylate can be used.
    The configuration of the necessary connections to carry out the procedure of
    5 resistivity measurement will be as follows: the cables connected to each disk of each electrode, will be connected to the positive pole of the power supply (8). The earth (5) of the same electrode must be connected to the negative pole of the power supply (8). The grounding (5) of the other electrode will be connected simultaneously by means of a welding point in the armature (10) and the measuring device of the
    10 voltage and current intensity (9) at its negative pole; This measuring system can be a multimeter or similar. The connections to the discs will be connected to the positive pole of the multimeter. In order that the described connection system constitutes a dielectric that allows establishing an electric field between the two electrodes of the sensor, the earth sockets (5) connected to the power supply (8) and the multimeter, are
    15 will fix at a single welding point in the reinforcement (10); which will serve as a control point or reference electrode.
    The present invention relates to an electrode manufactured only with two steel discs
    (1) and three discs of insulating polymeric material (2). However, they can be added
    20 as many steel discs as preferred. A greater number of discs will allow to obtain resistivity values in a greater range of concrete depth.
    权利要求:
    Claims (3)
    [1]
    1. Electric resistivity sensor integrated in concrete structures for measuring corrosion of steel, characterized by being attached to the steel frame
    5 of the concrete (11) by means of a welding point in the reinforcement (10) and embedded inside the concrete after concreting, which consists of a power supply (8) and a device for measuring the voltage and current intensity (9) ; said resistivity sensor is formed by two cylindrical electrodes manufactured by steel discs
    (1) and discs of insulating polymeric material (2), which are arranged alternately in
    10 layers fixed by a system of union between discs (6) by means of thread or adhesive and mounted on a rectangular support for fixing the electrodes (7) with an established distance between electrodes of 5 cm.
    [2]
    2. The electrical resistivity sensor according to claim 1 is characterized in that the
    15 electrodes have a central hole (4) through which the electrical connections between each disc of the electrode conductive material are established with a power supply (8), the voltage and current intensity measuring device (9) and the steel reinforcement of the concrete (11), which allows to establish an electric field between the two electrodes of the sensor.
    [3]
    3. The electrical resistivity sensor, according to claim 1, is characterized by having a power supply (8) that generates an alternating electric field of 172 Hz between the steel discs (1), located at the same depth.
    Figure 1 Figure. 2 Figure 3 Figure. 4
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    同族专利:
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US4861453A|1986-12-26|1989-08-29|Nippon Steel Corporation|Corrosion detecting probe for steel buried in concrete|
    US20080190296A1|2005-04-19|2008-08-14|Ohio University|Composite Discharge Electrode|
    US20080136425A1|2006-12-08|2008-06-12|Alexander Holst|Device for detecting the state of steel-reinforced concrete construction parts|
    US20150153399A1|2011-07-07|2015-06-04|Seiko Epson Corporation|Sensor device|
    WO2013189877A1|2012-06-18|2013-12-27|Commissariat à l'énergie atomique et aux énergies alternatives|Device for measuring the corrosion in a metallic structure or one comprising at least one metallic armour, associated uses and method|CN110361600A|2019-07-03|2019-10-22|东南大学|The measuring device and method of change in resistance in unsaturation concrete transmission process|
    WO2020208471A1|2019-04-09|2020-10-15|Politecnico Di Milano|System for measuring the electrical resistivity of concrete, at different depths, in new and existing structures|
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