WO2016042195A1 - Sensor for determining the depth and speed of carbonation of cement - Google Patents

Sensor for determining the depth and speed of carbonation of cement Download PDF

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Publication number
WO2016042195A1
WO2016042195A1 PCT/ES2015/070678 ES2015070678W WO2016042195A1 WO 2016042195 A1 WO2016042195 A1 WO 2016042195A1 ES 2015070678 W ES2015070678 W ES 2015070678W WO 2016042195 A1 WO2016042195 A1 WO 2016042195A1
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Prior art keywords
mixtures
metal oxide
sensor according
sensor
hydrogels
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PCT/ES2015/070678
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Spanish (es)
French (fr)
Inventor
José Manuel GANDÍA ROMERO
Eduardo GARCÍA BREIJO
Juan Soto Camino
Manuel Octavio VALCUENDE PAYÁ
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Universitat Politècnica De València (Upv)
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Publication of WO2016042195A1 publication Critical patent/WO2016042195A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
    • G01N17/02—Electrochemical measuring systems for weathering, corrosion or corrosion-protection measurement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N17/00—Investigating resistance of materials to the weather, to corrosion, or to light
    • G01N17/04—Corrosion probes
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/38—Concrete; Lime; Mortar; Gypsum; Bricks; Ceramics; Glass

Definitions

  • the present invention relates to a sensor system for determining the carbonation rate of concrete in real time. Therefore, the present invention can be framed in the technical field of construction, specifically in the field of concrete.
  • Carbonation is a chemical reaction in which calcium hydroxide reacts with carbon dioxide and forms insoluble calcium carbonate:
  • Carbonation is a slow process that occurs in concrete, where the portlandite (calcium hydroxide) of the cement reacts with the carbon dioxide in the air forming calcium carbonate. This reaction necessarily occurs in the presence of moisture, since carbon dioxide reacts with water forming carbonic acid, and it will react with calcium hydroxide, resulting in calcium carbonate and water. This carbonation process begins on the surface and slowly penetrates into the concrete. The speed depends on the relative humidity of the concrete. Since carbonation causes a decrease in pH (acid) this can cause corrosion of the reinforcements and damage the structural elements.
  • the present invention relates to a sensor system to be embedded in concrete structures and provide real-time information, reliably and continuously on the pH measurement. It also refers to a device that allows obtaining information at several points.
  • the device of the invention makes it possible to determine the depth of carbonation and the speed of advance of the carbonated front, being able to know well in advance at what time the corrosion of the reinforcements can begin. With this data, the maintenance processes of the structure can be optimized and any intervention anticipated well in advance, considerably reducing repair costs in the construction sector.
  • the introduction of these sensors in reinforced concrete structures, in the area of reinforcement coating allows the monitoring of the pH and, consequently, assessing the pH of the concrete in the area close to the reinforcements with a high degree of confidence. and therefore estimate the useful life of the structure.
  • the sensor can be implemented in:
  • a first aspect of the present invention relates to a pH sensor comprising: a) a track of an electrical conductor;
  • a metal oxide of at least one metal M where M is a metal that has at least two oxidation states, where the potential for reduction between said oxidation states varies with the pH;
  • c) means for electrical connection; characterized in that M does not form soluble species at pH> 7; Y
  • the support in which these components are present is a dielectric support and can be an alumina support, ceramic materials, enameled metals or rigid or flexible polymeric materials and can have varied geometries.
  • the sensor of the invention has flat geometry, although it can adopt any geometric configuration that allows intimate contact with the medium.
  • An electric conductor means a material that offers little resistance to electric charge movement.
  • an electrical conductor is a metal, metal alloys or graphite.
  • M is a metal that has at least two oxidation states.
  • M is a transition metal that does not form soluble species at pH> 7. Soluble species at these pH values are usually oxoanions.
  • the metal oxide is on the electric conductor track to detect potential variations.
  • dielectric material also called electrical insulator
  • the dielectric material means a material that is poorly conductive to electricity.
  • the dielectric material partially covers the electric conductor track, that is, it covers it completely except where it is in contact with the metal oxide and except in the area intended for the means for the electrical connection.
  • the dielectric material is selected from inorganic and polymeric dielectric materials.
  • the inorganic dielectric materials are selected from borosilicates, Al 2 0 3 , Zr0 2 ), mixtures of borosilicates with Ti0 3 Ba, mixtures of Al 2 0 with Ti0 3 Ba, mixtures of Zr0 2 with Ti0 3 Ba and any of their mixtures .
  • Polymeric dielectric materials are selected from acrylonitrile butadiene styrene (ABS), isobutylene-isoprene rubber, gutta-percha, high-density polyethylene (HDPE, high-density polyethylene), polyimide, neoprene rubber, polyamides, polycarbonate, polypropylene, polystyrene, polyvinylchloride, silicone, polytetrafluoroethylene (PTFE).
  • ABS acrylonitrile butadiene styrene
  • HDPE high-density polyethylene
  • polyimide polyimide
  • neoprene rubber polyamides
  • polycarbonate polypropylene
  • polystyrene polyvinylchloride
  • silicone polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • Hydrogel polymer is understood to mean hydrophilic polymers that form a three-dimensional network, water insoluble, elastic and that swell in the presence of water, considerably increasing their volume.
  • the hydrogel polymer is a polymer with crosslinking and having polar groups, preferably the polar groups are selected from -OH, -COOH, -CONH 2 , and -S0 3 H and any of their mixtures. Confined within the concrete, the hydrogel polymer will not significantly increase its volume, but will retain a certain amount of water around the sensor and in the capillary system of the concrete near the measuring element.
  • hydrogels are polyurethane hydrogels, polyethylene glycol, polypropylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, polyesters, carrageenans, collagens, polyvinyl methyl ether, polyacrylamide, poly (N-isopropylacrylamide), any of its copolymers and any of their mixtures.
  • the pH sensor comprises: a) a track of an electrical conductor;
  • a metal oxide of at least one metal M where M is a metal that has at least two oxidation states, where the potential for reduction between said oxidation states varies with the pH;
  • d) means for electrical connection; characterized in that M does not form soluble species at pH> 7; Y
  • the layer of dielectric material covers the electrical conductor track except in the area where the electrical conductor is in contact with the metal oxide and except where the electrical conductor is in contact with the means for electrical connection.
  • the metal oxide is selected from oxides of Ru, Ir, Rh, Nb, Ta and any of their mixtures, preferably the metal oxide is selected from Ru0 2 , Ir0 2 , Rh0 2 , Nb 2 0 5 , Ta 2 0 5 and any of its mixtures, more preferably the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures, and even more preferably the metal oxide is Ru0 2 .
  • An embodiment of the first aspect of the present invention relates to a pH sensor comprising: a) a track of an electrical conductor;
  • a metal oxide of at least one metal M on the electric conductor track, a metal oxide of at least one metal M, where M is a metal that has at least two oxidation states, where the potential for reduction between said oxidation states varies with the pH; c) a layer of dielectric material that partially covers the track of the electric conductor; Y
  • c) means for electrical connection; characterized in that M does not form soluble species at pH> 7; Y
  • the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures, preferably the metal oxide is Ru0 2 .
  • the metal oxide is embedded in an organic matrix.
  • the organic matrix is a thermosetting or photocurable polymer matrix, more preferably the organic matrix is selected from epoxy polymers, polyurethanes, polysiloxanes and any of their mixtures.
  • Epoxy polymers are thermostable polymers in whose synthesis monomers with epoxy groups are used.
  • Polyurethane polymers are polymers comprising organic units linked by carbamate (urethane) groups.
  • Polysiloxane polymers are also known as silicones and are polymers that comprise alternating silicon and oxygen atoms in their chain.
  • the metal oxide is embedded in an inorganic vitreous matrix, preferably the inorganic vitreous matrix is selected from borosilicates, borates or any of their mixtures.
  • borosilicate is meant glasses comprising silica, boric oxide, sodium and aluminum oxide, although it can also comprise oxides of other elements.
  • Borates means compounds of a polymeric nature that are obtained by a polymerization reaction of borate ions with metal cations or their oxides. This structure stabilizes and crystallizes when treated with a suitable heat treatment.
  • the metal oxide is embedded in an organic or inorganic matrix to prevent diffusion.
  • the mixture of metallic oxide and organic or inorganic matrix is what is deposited on the conductive track and what is coated with the hydrogel polymer.
  • the metal oxide is embedded with an organic or inorganic matrix and the weight ratio of metal oxide: organic / inorganic matrix is 4: 1 to 1: 4, preferably 2: 1 to 1: 2. If too much organic / inorganic matrix is added, the metal oxide can be completely coated by the matrix and its response would be reduced.
  • the hydrogel polymer is selected from polyacrylamide hydrogels, copolymer hydrogels comprising polyacrylamide, polyglycol hydrogels, polyurethane hydrogels, copolymer hydrogels comprising polyurethane and any mixture thereof, preferably the hydrogel polymer it is a hydrogel copolymer comprising polyurethane and more preferably the hydrogel polymer is a polyether polyurethane.
  • the electrical conductor is selected from Pt, Ag, Au, Pd, Al, Cu, Ni or any of its mixtures, preferably the electrical conductor is selected from Pd, Ag and any of its mixtures
  • a second aspect of the present invention relates to a device comprising at least one sensor as described above.
  • Potentiometry equipment and specific software continuously record the potential values of each of the sensors in real time that integrate the device.
  • the device is placed in the area covered by the reinforcements, before concreting the structure. At the moment that there is a decrease in pH (advance of the carbonated front), there is a variation in electrode potential, directly proportional to the variation in pH produced.
  • Wireless technology passive sensors, without power
  • wiring can be used to read the potentiometric data.
  • screen-printed connection terminals that allow a wired connection to the outside or a wireless connection module (for example of type of WiFi or Bluetooth type).
  • the measuring equipment consists of a multi-acquisition system for reading several channels, an amplifier system, a control system, a memory system, a display system and a data transmission system.
  • the sensor is embedded in the concrete and its reading is done during the service time of the pieces without acting on them.
  • the device comprises at least two sensors as described above. These devices have the additional advantage that the pH data of at least two sensors placed at a known distance can be used to calculate the velocity of the carbonated front.
  • the surface layer of concrete is more porous than the rest, and therefore, in that area the advance occurs more rapidly
  • the device comprises 3 sensors.
  • the device comprises 3 sensors and measures between 20 and 50 mm in length.
  • the device is between 5 and 15 mm wide.
  • a device with n sensors can be placed in line with m devices, creating a matrix of n x m sensors.
  • the device as described above further comprises a temperature sensor.
  • This temperature sensor can be a thermocouple, an NTC thermistor (Negative Temperature Coafficien ⁇ ), a PTC thermistor (Positive Temparature Coeff ⁇ cient), a platinum resistive temperature detector (PTR), Platinum Resistance Thermometer and semiconductor temperature sensors surface adhered with resins
  • the device as described above further comprises a transducer of the reduction potential to an electrical signal and means for detecting said electrical signal.
  • a third aspect of the present invention relates to a method of obtaining a sensor, as described above, comprising the following steps: a) depositing the electric conductor track on a dielectric support;
  • step (b) on the electric conductor track obtained in step (a), depositing a metal oxide of a metal M, where M is a metal that can have at least two oxidation states,
  • M does not form soluble species at pH> 7;
  • Stages (a), (b), (c) and (d) can perform the following techniques: Sputtering is a physical process in which it occurs the vaporization of the atoms of a solid material called "white” by bombarding it by energy ions.
  • Screen printing (screen-printing, in English) is a printing technique used on any material, and consists of transferring an ink through a tensioned mesh in a frame.
  • Spray-coating technique used in the manufacture of components that consists of projecting small particles, with a nozzle, as a spray.
  • Huecogravure (gravure, in English) is a technique that uses a printing cylinder, which basically consists of a metallic cylinder, a layer of copper on which the motif to be printed will be engraved, usually on flexible supports. This technique requires that what is to be deposited be flexible.
  • Printing (ink-jet printing, in English) is printing of inks, similar to a printer.
  • a heat treatment is carried out between 300 ° C and 1200 ° C, preferably between 600 ° C and 1000 ° C and more preferably on 800 ° C
  • the metal oxide is selected from Ru, Ir, Rh, Nb, Ta and any of its mixtures, preferably the metal oxide is selected from Ru0 2 , Ir0 2 , Rh0 2 , Nb 2 0 5 , Ta 2 0 5 , and any of its mixtures, more preferably the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures, and even more preferably the metal oxide is Ru0 2 .
  • the metal oxide is preferably embedded in an organic or inorganic matrix before depositing. Once deposited, it is subjected to a heat treatment to adhere to the conductive track.
  • the metal oxide is embedded in an organic matrix before depositing it, preferably the organic matrix is a thermosetting or photocurable polymeric matrix, more preferably the organic matrix is selected from epoxy polymers, polyurethanes, polysiloxanes and any of their mixtures.
  • the organic matrix with the embedded metal oxide is subjected to a heat treatment between 40 ° C and 150 ° C, preferably between 50 ° C and 100 ° C.
  • the metal oxide is embedded in an inorganic matrix before depositing it. Subsequently to deposit it on the support, the inorganic matrix with the embedded metal oxide is subjected to a heat treatment between 500 ° C and 1200 ° C, preferably between 700 ° C and 900 ° C.
  • a layer of hydrogel polymer is deposited on the metal oxide, which is necessary to retain surface moisture on the oxide and ensure the sensor response for a long time. It can be deposited by screen printing and subsequently cured at about 40-60 ° C.
  • the hydrogel polymer is selected from polyacrylamide hydrogels, copolymer hydrogels comprising polyacrylamide, polyglycol hydrogels, polyurethane hydrogels, copolymer hydrogels comprising polyurethane and any mixture thereof, preferably the hydrogel polymer it is a hydrogel copolymer comprising polyurethane and more preferably the hydrogel polymer is a polyether polyurethane.
  • a layer of hydrogel polymer is deposited on the metal oxide, which is necessary to retain surface moisture on the oxide and ensure the long-term sensor response. After depositing it is cured at about 40-60 ° C.
  • the electrical conductor is selected from Pt, Ag, Au, Pd, Al, Cu, Ni or any of its mixtures, preferably the electrical conductor is selected from Pd, Ag and any of its mixtures
  • the dielectric layer is an inorganic dielectric material and is selected from borosilicates, Al 2 0 3 , Zr0 2 ), mixtures of borosilicates with Ti0 3 Ba, mixtures of Al 2 0 with Ti0 3 Ba, mixtures of Zr0 2 with Ti0 3 Ba and any of its mixtures.
  • the dielectric layer is a polymeric dielectric material and is selected from acrylonitrile butadiene styrene (ABS), isobutylene-isoprene rubber, gutta-percha, high density polyethylene (HDPE, high-density polyethylene ), polyimide, neoprene rubber, polyamides, polycarbonate, polypropylene, polystyrene, polyvinylchloride, silicone, polytetrafluoroethylene (PTFE).
  • ABS acrylonitrile butadiene styrene
  • HDPE high-density polyethylene
  • polyimide neoprene rubber
  • polyamides polycarbonate
  • polypropylene polystyrene
  • polystyrene polyvinylchloride
  • silicone polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • a fourth aspect of the present invention relates to the use thereof as defined above to measure the pH of concrete.
  • a fifth aspect of the present invention relates to the use of the device as described above to measure the pH of concrete.
  • FIG. 1 Potential variation as a function of the time detected by a sensor of the invention inside a concrete block. E: Potential in V; T: time in hours.
  • FIG. 3 Potential variation as a function of the time detected by a device comprising 3 sensors of the invention.
  • E Potential in V
  • T time in days
  • t1, t2 and t3 arrival times of the carbonated front for each of the sensors of the device.
  • FIG. 4 Scheme of a device of the invention comprising 3 sensors. 1: support; 2 and 3: conductive track; 3: electrical connection zone; 4: metal oxide.
  • Example 1 Procedure for obtaining a device of the invention
  • This example describes the method of obtaining a device comprising 3 sensors of the invention, illustrated in Figure 4.
  • the electrical conductor was deposited on an alumina substrate to form the conductive tracks [2] and the connector area [3]. These tracks were obtained by heat treatment (800-900 ° C, 1 h) of the screen printing of an Ag / Pd paste.
  • the sensor system has a terminal zone [3] for the electrical connection to the information reading equipment.
  • the conductive tracks of the temperature sensors are screen printed on the reverse and the same heat treatment is applied.
  • Ruthenium oxide (Ru0 2 ) [4] was then deposited on the conductive tracks. After a heat treatment (burned at about 700 ° C), the organic vehicle (terpineol-butanol) was removed while adhering and stabilizing the metal oxide on the conductive track.
  • a dielectric layer was added which is a dielectric polymer (D-GWENT D50706P3) covering the different conductive tracks but leaving the active surface of the sensor oxide and the area of the electrical connection free.
  • D-GWENT D50706P3 a dielectric polymer covering the different conductive tracks but leaving the active surface of the sensor oxide and the area of the electrical connection free.
  • the curing of this dielectric is around 100 ° C. Temperature sensor assembly in surface mount technology and subsequent protection with an elastomeric gel that prevents moisture on the sensors.
  • a hydrophilic membrane was deposited on the metal oxide sensor element.
  • the hydrophilic membrane used was prepared by dissolving 500 mg of the commercial HydroMed D4 gel, which is a polyether polyurethane with an approximate water content of 50%, dissolved in 5.4 grams of ethyl alcohol to which 0.5 ml has been added. of distilled water. The mixture is introduced into a tube inside the ultrasound for 5 minutes. The resulting solution is deposited with a dropper on the sensor elements of ruthenium oxide and allowed to dry in an oven at 40 ° C. The hydrogel dosage can be applied several consecutive times to increase the thickness of the hydrophilic layer.
  • the sensor of example 1 was placed in the area of the reinforcement covering, before concreting the structure. At the moment that a sensor detects the advance of the carbonated front (lowering of pH), there is an important variation of the electrode potential, directly proportional to the variation of pH produced (Fig. 1).
  • FIG. 2 shows a photograph of the advance of the carbonated front (colorless area in a concrete sample with phenolphthalein).
  • fig. 3 shows a graph that illustrates the potential variation over time of three sensors placed at different distances. As the distance between the surface of the concrete and the first sensor is known, as well as the distances between the different sensors, knowing the times it takes for the different sensors to begin to vary their potential, you can automatically know at what speed the carbonated front advances.
  • An advantage of the device comprising more than one sensor, where the distance between the sensors is well defined, is that the distance between the first sensor and the surface of the concrete is not normally a precise data, due to the process of execution in a work, however, the distances between the different sensors of the device itself is a value that is known with total precision.

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Abstract

The invention relates to a pH sensor comprising: a strip of an electrical conductor; a metal oxide of at least one metal M on the electrical conductor strip, where M is a metal that presents at least two oxidation states, where the reduction potential between said oxidation states varies with the pH; a layer of dielectric material that partially covers the electrical conductor strip; and electrical connection means, characterised in that M does not form soluble species at pH >7, and in that the metal oxide is coated by a hydrogel polymer.

Description

SENSOR PARA LA DETERMINACIÓN DE LA PROFUNDIDAD Y VELOCIDAD DE SENSOR FOR DETERMINATION OF DEPTH AND SPEED OF
CARBONATACION DEL HORMIGÓN CONCRETE CARBONATION
DESCRIPCIÓN DESCRIPTION
La presente invención se refiere a un sistema sensor para determinar la velocidad de carbonatacion del hormigón a tiempo real. Por tanto, la presente invención se puede encuadrar en el campo técnico de la construcción, en concreto en el campo del hormigón. The present invention relates to a sensor system for determining the carbonation rate of concrete in real time. Therefore, the present invention can be framed in the technical field of construction, specifically in the field of concrete.
ESTADO DE LA TÉCNICA STATE OF THE TECHNIQUE
La carbonatacion es una reacción química en la que el hidróxido de calcio reacciona con el dióxido de carbono y forma carbonato cálcico insoluble: Carbonation is a chemical reaction in which calcium hydroxide reacts with carbon dioxide and forms insoluble calcium carbonate:
Ca(OH)2 + C02→ CaC03 + H20 Ca (OH) 2 + C0 2 → CaC0 3 + H 2 0
La carbonatacion es un proceso lento que ocurre en el hormigón, donde la portlandita (hidróxido cálcico) del cemento reacciona con el dióxido de carbono del aire formando carbonato cálcico. Esta reacción necesariamente se produce en presencia de humedad, ya que el dióxido de carbono reacciona con el agua formando ácido carbónico, y éste reaccionará con el hidróxido de calcio, obteniendo como resultado el carbonato de calcio y agua. Este proceso de carbonatacion empieza en la superficie y lentamente va penetrando al interior del hormigón. La velocidad depende de la humedad relativa del hormigón. Dado que la carbonatacion provoca una bajada de pH (ácido) esto puede ocasionar la corrosión de las armaduras y dañar los elementos estructurales. Carbonation is a slow process that occurs in concrete, where the portlandite (calcium hydroxide) of the cement reacts with the carbon dioxide in the air forming calcium carbonate. This reaction necessarily occurs in the presence of moisture, since carbon dioxide reacts with water forming carbonic acid, and it will react with calcium hydroxide, resulting in calcium carbonate and water. This carbonation process begins on the surface and slowly penetrates into the concrete. The speed depends on the relative humidity of the concrete. Since carbonation causes a decrease in pH (acid) this can cause corrosion of the reinforcements and damage the structural elements.
Obtener información de pH y del frente de carbonatacion es una información muy importante ya que no detectar daños estructurales debidos a corrosión puede provocar el colapso de la estructura. La importancia de este tipo de sensores viene ilustrada por los artículos Effective monitoring of corrosión in reinforcing steel in concrete constructions by a multifunctional sensor (Shi-Gang Dong, Electrochimica Acta, Vol. 56, 4, 2011 , págs. 1881-1888) y Sensor systems for use in reinforced concrete structures (W.John McCarter, Construction and Building Materials, Vol. 18, 6, 2004, págs. 351-358) se describen diversos sensores de pH para hormigón. Obtaining pH and carbonation front information is very important information since not detecting structural damage due to corrosion can cause the structure to collapse. The importance of this type of sensors is illustrated by the articles Effective monitoring of corrosion in reinforcing steel in concrete constructions by a multifunctional sensor (Shi-Gang Dong, Electrochimica Acta, Vol. 56, 4, 2011, pp. 1881-1888) and Sensor systems for use in reinforced concrete structures (W. John McCarter, Construction and Building Materials, Vol. 18, 6, 2004, P. 351-358) various pH sensors for concrete are described.
La patente US201101 15613, publicada en 201 1 , describe sensores wireless para medir el pH, la temperatura y la distorsión en hormigón. Sin embargo, el sensor de pH descrito en este documento es un electrodo de vidrio estándar , y por tanto, presenta problemas al ser utilizado en el entorno específico del hormigón por su falta de robustez y por la imposibilidad de realizar un mantenimiento. US201101 15613, published in 201 1, describes wireless sensors for measuring pH, temperature and distortion in concrete. However, the pH sensor described in this document is a standard glass electrode, and therefore, presents problems when used in the specific concrete environment due to its lack of robustness and the impossibility of maintenance.
Por tanto, existe la necesidad de buscar sensores de pH para hormigón alternativos que presenten robustez y que indiquen adecuadamente los cambios de pH en el interior del hormigón. Therefore, there is a need to look for alternative pH sensors for concrete that are robust and that adequately indicate the pH changes inside the concrete.
DESCRIPCIÓN DE LA INVENCIÓN DESCRIPTION OF THE INVENTION
La presente invención se refiere a un sistema sensor para ser embebido en estructuras de hormigón y aportar información en tiempo real, de forma fiable y continua sobre la medida del pH. Además se refiere a un dispositivo que permite obtener la información en varios puntos. El dispositivo de la invención permite determinar la profundidad de carbonatación y la velocidad de avance del frente carbonatado, pudiendo conocer con mucha antelación en qué momento se puede iniciar la corrosión de las armaduras. Con estos datos se pueden optimizar los procesos de mantenimiento de la estructura y prever con suficiente antelación cualquier intervención, reduciéndose considerablemente los costes de reparación en el sector de la construcción. En definitiva, la introducción de estos sensores en las estructuras de hormigón armado, en la zona de recubrimiento de las armaduras, permite la monitorización del pH y en consecuencia evaluar con un alto grado de confianza el pH del hormigón en la zona próxima a las armaduras y por tanto estimar la vida útil de la estructura. El sensor se puede implementar en: The present invention relates to a sensor system to be embedded in concrete structures and provide real-time information, reliably and continuously on the pH measurement. It also refers to a device that allows obtaining information at several points. The device of the invention makes it possible to determine the depth of carbonation and the speed of advance of the carbonated front, being able to know well in advance at what time the corrosion of the reinforcements can begin. With this data, the maintenance processes of the structure can be optimized and any intervention anticipated well in advance, considerably reducing repair costs in the construction sector. In short, the introduction of these sensors in reinforced concrete structures, in the area of reinforcement coating, allows the monitoring of the pH and, consequently, assessing the pH of the concrete in the area close to the reinforcements with a high degree of confidence. and therefore estimate the useful life of the structure. The sensor can be implemented in:
- obras de nueva planta, incorporándolo en el momento de la puesta en obra del hormigón en aquellas zonas de la estructura más expuestas al ingreso de C02 y por tanto, donde el hormigón puede carbonatarse con mayor rapidez, permitiendo controlar así el avance del frente carbonatado y la velocidad de avance del mismo al disponer de varios sensores a distintas profundidades; - en obras de intervención, permitiendo un control y un seguimiento no destructivo de la eficacia de la reparación; - new plant works, incorporating it at the time of the concrete work in those areas of the structure most exposed to the entrance of C0 2 and therefore, where the concrete can be carbonated more quickly, allowing to control the advance of the front carbonated and the speed of advance of the same to have several sensors at different depths; - in intervention works, allowing non-destructive control and monitoring of the effectiveness of the repair;
- en laboratorio, para trabajos de investigación con probetas para poder profundizar en el conocimiento de los procesos de corrosión de las armaduras embebidas en hormigón y poder estudiar los cambios que se van produciendo en cada momento en el material para mejorar su conocimiento y obtener modelos de predicción más fiables de la velocidad de difusión del C02 al interior del hormigón. - in the laboratory, for research work with specimens to be able to deepen the knowledge of the corrosion processes of the reinforcements embedded in concrete and to be able to study the changes that are occurring at any time in the material to improve their knowledge and obtain models of more reliable prediction of the diffusion rate of C0 2 inside the concrete.
Cabe resaltar que el uso de este tipo de sensores permite obtener información del pH a diferentes profundidades en la zona de recubrimiento de las armaduras embebidas en el hormigón sin necesidad de aplicar ensayos destructivos como el de la fenolftaleína o la termogravimetría. It should be noted that the use of this type of sensors allows obtaining pH information at different depths in the area of coating of the reinforcements embedded in the concrete without the need for destructive tests such as phenolphthalein or thermogravimetry.
Por tanto, un primer aspecto de la presente invención se refiere a un sensor de pH que comprende: a) una pista de un conductor eléctrico; Therefore, a first aspect of the present invention relates to a pH sensor comprising: a) a track of an electrical conductor;
b) sobre la pista de conductor eléctrico, un óxido metálico de al menos un metal M, donde M es un metal que presenta al menos dos estados de oxidación, donde el potencial de reducción entre dichos estados de oxidación varía con el pH; b) on the electric conductor track, a metal oxide of at least one metal M, where M is a metal that has at least two oxidation states, where the potential for reduction between said oxidation states varies with the pH;
c) una capa de material dieléctrico que cubre parcialmente la pista del conductor eléctrico; y c) a layer of dielectric material that partially covers the track of the electric conductor; Y
c) medios para conexión eléctrica; caracterizado porque M no forma especies solubles a pH > 7; y c) means for electrical connection; characterized in that M does not form soluble species at pH> 7; Y
porque el óxido metálico está recubierto de un polímero hidrogel. because the metal oxide is coated with a hydrogel polymer.
El soporte en el que están presentes estos componentes es un soporte dieléctrico y puede ser un soporte de alúmina, materiales cerámicos, metales esmaltados o materiales poliméricos rígidos o flexibles y puede tener geometrías variadas. Preferiblemente el sensor de la invención tiene geometría plana, aunque puede adoptar cualquier configuración geométrica que permita un íntimo contacto con el medio. Por conductor eléctrico se entiende un material que ofrece poca resistencia al movimiento de carga eléctrica. En el contexto de la invención, un conductor eléctrico es un metal, aleaciones de metal o grafito. The support in which these components are present is a dielectric support and can be an alumina support, ceramic materials, enameled metals or rigid or flexible polymeric materials and can have varied geometries. Preferably the sensor of the invention has flat geometry, although it can adopt any geometric configuration that allows intimate contact with the medium. An electric conductor means a material that offers little resistance to electric charge movement. In the context of the invention, an electrical conductor is a metal, metal alloys or graphite.
Tal y como se ha indicado anteriormente, M es un metal que presenta al menos dos estados de oxidación. Preferiblemente M es un metal de transición que no forma especies solubles a pH >7. Las especies solubles a esos valores de pH suelen ser oxoaniones. As indicated above, M is a metal that has at least two oxidation states. Preferably M is a transition metal that does not form soluble species at pH> 7. Soluble species at these pH values are usually oxoanions.
El óxido metálico está sobre la pista de conductor eléctrico para poder detectar variaciones de potencial. The metal oxide is on the electric conductor track to detect potential variations.
Por material dieléctrico (también llamado aislante eléctrico) se entiende un material mal conductor de la electricidad. El material dieléctrico cubre parcialmente la pista de conductor eléctrico, es decir, lo cubre totalmente excepto donde está en contacto con el óxido metálico y excepto en el área destinada a los medios para la conexión eléctrica. El material dieléctrico se selecciona de materiales dieléctricos inorgánicos y poliméricos. Preferiblemente los materiales dieléctricos inorgánicos se seleccionan de borosilicatos, Al203, Zr02), mezclas de borosilicatos con Ti03Ba, mezclas de Al20 con Ti03Ba, mezclas de Zr02 con Ti03Ba y cualquiera de sus mezclas. Los materiales dieléctricos poliméricos se seleccionan de acrilonitrilo butadieno estireno (ABS), caucho isobutileno-isopreno, gutapercha, polietileno de alta densidad (del inglés HDPE, high-density polyethylene), poliimida, caucho de neopreno, poliamidas, policarbonato, polipropileno, poliestireno, policloruro de vinilo, silicona, politetrafluoroetileno (PTFE). Preferiblemente el material dieléctrico es un material dieléctrico polimérico. By dielectric material (also called electrical insulator) means a material that is poorly conductive to electricity. The dielectric material partially covers the electric conductor track, that is, it covers it completely except where it is in contact with the metal oxide and except in the area intended for the means for the electrical connection. The dielectric material is selected from inorganic and polymeric dielectric materials. Preferably the inorganic dielectric materials are selected from borosilicates, Al 2 0 3 , Zr0 2 ), mixtures of borosilicates with Ti0 3 Ba, mixtures of Al 2 0 with Ti0 3 Ba, mixtures of Zr0 2 with Ti0 3 Ba and any of their mixtures . Polymeric dielectric materials are selected from acrylonitrile butadiene styrene (ABS), isobutylene-isoprene rubber, gutta-percha, high-density polyethylene (HDPE, high-density polyethylene), polyimide, neoprene rubber, polyamides, polycarbonate, polypropylene, polystyrene, polyvinylchloride, silicone, polytetrafluoroethylene (PTFE). Preferably the dielectric material is a polymeric dielectric material.
Por polímero hidrogel se entiende polímeros hidrófilos que forman una red tridimensional, insolubles en agua, elásticos y que en presencia de agua se hinchan aumentando considerablemente su volumen. El polímero hidrogel es un polímero con entrecruzamiento y que tiene grupos polares, preferiblemente los grupos polares se seleccionan de -OH, -COOH, -CONH2, y -S03H y cualquiera de sus mezclas. Confinado dentro del hormigón, el polímero hidrogel no aumentará considerablemente su volumen, pero retendrá una cierta cantidad de agua en los alrededores del sensor y en el sistema capilar del hormigón próximo al elemento de medida. Ejemplos no limitantes de hidrogeles son hidrogeles de poliuretano, polietilenglicol, polipropilenglicol, polivinilpirrolidona, polivinilalcohol, ácido poliacrílico, poliésteres, carragenanos, colágenos, polivinilmetiléter, poliacrilamida, poli (N-isopropilacrilamida), cualquiera de sus copolímeros y cualquiera de sus mezclas. En una realización del primer aspecto de la presente invención, el sensor de pH comprende: a) una pista de un conductor eléctrico; Hydrogel polymer is understood to mean hydrophilic polymers that form a three-dimensional network, water insoluble, elastic and that swell in the presence of water, considerably increasing their volume. The hydrogel polymer is a polymer with crosslinking and having polar groups, preferably the polar groups are selected from -OH, -COOH, -CONH 2 , and -S0 3 H and any of their mixtures. Confined within the concrete, the hydrogel polymer will not significantly increase its volume, but will retain a certain amount of water around the sensor and in the capillary system of the concrete near the measuring element. Non-limiting examples of hydrogels are polyurethane hydrogels, polyethylene glycol, polypropylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, polyesters, carrageenans, collagens, polyvinyl methyl ether, polyacrylamide, poly (N-isopropylacrylamide), any of its copolymers and any of their mixtures. In an embodiment of the first aspect of the present invention, the pH sensor comprises: a) a track of an electrical conductor;
b) sobre la pista de conductor eléctrico, un óxido metálico de al menos un metal M, donde M es un metal que presenta al menos dos estados de oxidación, donde el potencial de reducción entre dichos estados de oxidación varía con el pH; b) on the electric conductor track, a metal oxide of at least one metal M, where M is a metal that has at least two oxidation states, where the potential for reduction between said oxidation states varies with the pH;
c) una capa de material dieléctrico que cubre parcialmente la pista del conductor eléctrico; y c) a layer of dielectric material that partially covers the track of the electric conductor; Y
d) medios para conexión eléctrica; caracterizado porque M no forma especies solubles a pH > 7; y d) means for electrical connection; characterized in that M does not form soluble species at pH> 7; Y
porque el óxido metálico está recubierto de un polímero hidrogel; y because the metal oxide is coated with a hydrogel polymer; Y
porque la capa de material dieléctrico cubre la pista de conductor eléctrico excepto en el área donde el conductor eléctrico está en contacto con el óxido metálico y excepto donde el conductor eléctrico está en contacto con los medios para conexión eléctrica. because the layer of dielectric material covers the electrical conductor track except in the area where the electrical conductor is in contact with the metal oxide and except where the electrical conductor is in contact with the means for electrical connection.
En otra realización del primer aspecto de la presente invención, el óxido metálico se selecciona de óxidos de Ru, Ir, Rh, Nb, Ta y cualquiera de sus mezclas, preferiblemente el óxido metálico se selecciona de Ru02, Ir02, Rh02, Nb205, Ta205 y cualquiera de sus mezclas, más preferiblemente el óxido metálico se selecciona de Ru02, Ir02 y cualquiera de sus mezclas, y aún más preferiblemente el óxido metálico es Ru02. In another embodiment of the first aspect of the present invention, the metal oxide is selected from oxides of Ru, Ir, Rh, Nb, Ta and any of their mixtures, preferably the metal oxide is selected from Ru0 2 , Ir0 2 , Rh0 2 , Nb 2 0 5 , Ta 2 0 5 and any of its mixtures, more preferably the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures, and even more preferably the metal oxide is Ru0 2 .
Una realización del primer aspecto de la presente invención, se refiere a un sensor de pH que comprende: a) una pista de un conductor eléctrico; An embodiment of the first aspect of the present invention relates to a pH sensor comprising: a) a track of an electrical conductor;
b) sobre la pista de conductor eléctrico, un óxido metálico de al menos un metal M, donde M es un metal que presenta al menos dos estados de oxidación, donde el potencial de reducción entre dichos estados de oxidación varía con el pH; c) una capa de material dieléctrico que cubre parcialmente la pista del conductor eléctrico; y b) on the electric conductor track, a metal oxide of at least one metal M, where M is a metal that has at least two oxidation states, where the potential for reduction between said oxidation states varies with the pH; c) a layer of dielectric material that partially covers the track of the electric conductor; Y
c) medios para conexión eléctrica; caracterizado porque M no forma especies solubles a pH > 7; y c) means for electrical connection; characterized in that M does not form soluble species at pH> 7; Y
porque el óxido metálico está recubierto de un polímero hidrogel; y because the metal oxide is coated with a hydrogel polymer; Y
porque la capa de material dieléctrico cubre la pista de conductor eléctrico excepto en el área donde el conductor eléctrico está en contacto con el óxido metálico y excepto donde el conductor eléctrico está en contacto con los medios para conexión eléctrica; y because the layer of dielectric material covers the electrical conductor track except in the area where the electrical conductor is in contact with the metal oxide and except where the electrical conductor is in contact with the means for electrical connection; Y
porque el óxido metálico se selecciona de Ru02, Ir02 y cualquiera de sus mezclas, preferiblemente el óxido metálico es Ru02. Because the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures, preferably the metal oxide is Ru0 2 .
Al variar en el hormigón la concentración de iones hidronio, se produce una variación del potencial en el electrodo. Esta variación es aproximadamente lineal con el pH con una pendiente aproximada de 59 mV, es decir, el proceso redox a través del cual el metal M cambia de estado de oxidación presenta comportamiento nernstiano. When the concentration of hydronium ions varies in concrete, there is a variation in the electrode potential. This variation is approximately linear with the pH with an approximate slope of 59 mV, that is to say, the redox process through which the metal M changes in oxidation state exhibits nernstian behavior.
En otra realización del primer aspecto de la presente invención, el óxido metálico está embebido en una matriz orgánica. Por embebido en el contexto de la invención se entiende mezclado físicamente. La matriz orgánica es una matriz polimérica termocurable o fotocurable, más preferiblemente la matriz orgánica se selecciona de polímeros epoxis, poliuretanos, polisiloxanos y cualquiera de sus mezclas. Polímeros epoxis son polímeros termoestables en cuya síntesis se utilizan monómeros con grupos epoxi. Polímeros poliuretanos son polímeros que comprende unidades orgánicas enlazadas por grupos carbamato (uretano). Los polímeros polisiloxanos también se conocen como siliconas y son polímeros que comprenden en su cadena átomos de silicio y de oxígeno alternados. In another embodiment of the first aspect of the present invention, the metal oxide is embedded in an organic matrix. Embedded in the context of the invention is understood to be physically mixed. The organic matrix is a thermosetting or photocurable polymer matrix, more preferably the organic matrix is selected from epoxy polymers, polyurethanes, polysiloxanes and any of their mixtures. Epoxy polymers are thermostable polymers in whose synthesis monomers with epoxy groups are used. Polyurethane polymers are polymers comprising organic units linked by carbamate (urethane) groups. Polysiloxane polymers are also known as silicones and are polymers that comprise alternating silicon and oxygen atoms in their chain.
En otra realización del primer aspecto de la presente invención, el óxido metálico está embebido en una matriz vitrea inorgánica, preferiblemente la matriz vitrea inorgánica se selecciona de borosilicatos, boratos o cualquiera de sus mezclas. Por borosilicato se entiende vidrios que comprenden sílice, óxido bórico, óxido de sodio y óxido de aluminio, aunque también puede comprender óxidos de otros elementos. In another embodiment of the first aspect of the present invention, the metal oxide is embedded in an inorganic vitreous matrix, preferably the inorganic vitreous matrix is selected from borosilicates, borates or any of their mixtures. By borosilicate is meant glasses comprising silica, boric oxide, sodium and aluminum oxide, although it can also comprise oxides of other elements.
Por boratos se entiende compuestos de carácter polimérico que se obtienen por una reacción de polimerización de los iones borato con cationes metálicos o sus óxidos. Este estructura se estabiliza y cristaliza cuando el tratamiento con un tratamiento térmico adecuado. Borates means compounds of a polymeric nature that are obtained by a polymerization reaction of borate ions with metal cations or their oxides. This structure stabilizes and crystallizes when treated with a suitable heat treatment.
El óxido metálico se embebe en una matriz orgánica o inorgánica para evitar su difusión. La mezcla de óxido metálico y matriz orgánico o inorgánica es lo que se deposita sobre la pista conductora y lo que se recubre con el polímero hidrogel. The metal oxide is embedded in an organic or inorganic matrix to prevent diffusion. The mixture of metallic oxide and organic or inorganic matrix is what is deposited on the conductive track and what is coated with the hydrogel polymer.
En otra realización del primer aspecto de la presente invención, el óxido metálico está embebido con una matriz orgánica o inorgánica y el ratio en peso de óxido metálico: matriz orgánica/inorgánica es de 4:1 a 1 :4, preferiblemente de 2: 1 a 1 :2. Si se añade demasiada matriz orgánica/inorgánica el óxido metálico puede quedar totalmente recubierto por la matriz y se mermaría su respuesta. In another embodiment of the first aspect of the present invention, the metal oxide is embedded with an organic or inorganic matrix and the weight ratio of metal oxide: organic / inorganic matrix is 4: 1 to 1: 4, preferably 2: 1 to 1: 2. If too much organic / inorganic matrix is added, the metal oxide can be completely coated by the matrix and its response would be reduced.
En otra realización del primer aspecto de la presente invención, el polímero hidrogel se selecciona de hidrogeles de poliacrilamida, hidrogeles copolímeros que comprenden poliacrilamida, hidrogeles de poliglicoles, hidrogeles de poliuretano, hidrogeles copolímeros que comprenden poliuretano y cualquiera de sus mezclas, preferiblemente el polímero hidrogel es hidrogel copolímero que comprende poliuretano y más preferiblemente el polímero hidrogel es un poliéter-poliuretano. In another embodiment of the first aspect of the present invention, the hydrogel polymer is selected from polyacrylamide hydrogels, copolymer hydrogels comprising polyacrylamide, polyglycol hydrogels, polyurethane hydrogels, copolymer hydrogels comprising polyurethane and any mixture thereof, preferably the hydrogel polymer it is a hydrogel copolymer comprising polyurethane and more preferably the hydrogel polymer is a polyether polyurethane.
En otra realización del primer aspecto de la presente invención, el conductor eléctrico se selecciona de Pt, Ag, Au, Pd, Al, Cu, Ni o cualquiera de sus mezclas, preferiblemente el conductor eléctrico se selecciona de Pd, Ag y cualquiera de sus mezclas. In another embodiment of the first aspect of the present invention, the electrical conductor is selected from Pt, Ag, Au, Pd, Al, Cu, Ni or any of its mixtures, preferably the electrical conductor is selected from Pd, Ag and any of its mixtures
Un segundo aspecto de la presente invención se refiere a un dispositivo que comprende al menos un sensor tal y como se ha descrito anteriormente. A second aspect of the present invention relates to a device comprising at least one sensor as described above.
Mediante un equipo de potenciometría y un software específico se van registrando de forma continua en tiempo real los valores de potencial de cada uno de los sensores que integran el dispositivo. Potentiometry equipment and specific software continuously record the potential values of each of the sensors in real time that integrate the device.
El dispositivo se coloca en la zona de recubrimiento de las armaduras, antes del hormigonado de la estructura. En el momento que hay una bajada de pH (avance del frente carbonatado), se produce una variación de potencial del electrodo, directamente proporcional a la variación de pH producida. The device is placed in the area covered by the reinforcements, before concreting the structure. At the moment that there is a decrease in pH (advance of the carbonated front), there is a variation in electrode potential, directly proportional to the variation in pH produced.
Para la lectura de los datos potenciométricos se puede utilizar tecnología Wireless (sensores pasivos, sin alimentación) o cableado. En el extremo de las pistas conductoras se disponen unos terminales de conexión serigrafiados que permiten una conexión cableada con el exterior o un módulo de conexión inalámbrica (por ejemplo de tipo de tipo WiFi o Bluetooth). Wireless technology (passive sensors, without power) or wiring can be used to read the potentiometric data. At the end of the conductive tracks there are screen-printed connection terminals that allow a wired connection to the outside or a wireless connection module (for example of type of WiFi or Bluetooth type).
El equipo de medida consta de un sistema multiadquisición para la lectura de varios canales, un sistema amplificador, un sistema de control, un sistema de memoria, un sistema de visualización y un sistema de transmisión de datos. The measuring equipment consists of a multi-acquisition system for reading several channels, an amplifier system, a control system, a memory system, a display system and a data transmission system.
El sensor queda embebido en el hormigón y su lectura se realiza durante el tiempo de servicio de las piezas sin actuar sobre ellas. The sensor is embedded in the concrete and its reading is done during the service time of the pieces without acting on them.
En una realización del segundo aspecto de la presente invención, el dispositivo comprende al menos dos sensores tal y como se han descrito anteriormente. Estos dispositivos presentan la ventaja adicional de que se pueden utilizar los datos de pH de al menos dos sensores colocados a una distancia conocida para calcular la velocidad del frente carbonatado. In an embodiment of the second aspect of the present invention, the device comprises at least two sensors as described above. These devices have the additional advantage that the pH data of at least two sensors placed at a known distance can be used to calculate the velocity of the carbonated front.
Esta velocidad no es uniforme sino que cada vez es más lenta y por ello es importante incorporar varios sensores, ya que: This speed is not uniform but is increasingly slow and therefore it is important to incorporate several sensors, since:
- la capa superficial de hormigón es más porosa que el resto, y por lo tanto, en esa zona el avance se produce más rápidamente,  - the surface layer of concrete is more porous than the rest, and therefore, in that area the advance occurs more rapidly,
- a medida que se carbonata el hormigón los nuevos compuestos que se forman colmatan los poros del hormigón y la velocidad de avance disminuye.  - As the concrete is carbonated, the new compounds that form fill the pores of the concrete and the feed rate decreases.
En una realización del segundo aspecto de la presente invención, el dispositivo comprende 3 sensores. Preferiblemente el dispositivo comprende 3 sensores y mide entre 20 y 50 mm de longitud. Preferiblemente el dispositivo mide entre 5 y 15 mm de ancho. In an embodiment of the second aspect of the present invention, the device comprises 3 sensors. Preferably the device comprises 3 sensors and measures between 20 and 50 mm in length. Preferably the device is between 5 and 15 mm wide.
Un dispositivo con n sensores se puede colocar en línea con m dispositivos, creando una matriz de n x m sensores. A device with n sensors can be placed in line with m devices, creating a matrix of n x m sensors.
En otra realización del segundo aspecto de la presente invención, el dispositivo tal y como se ha descrito anteriormente además comprende un sensor de temperatura. Este sensor de temperatura puede ser un termopar, un termistor NTC (Negativa Temperatura Coafficiení), un termistor PTC (Positiva Temparature Coeffícient), un detector de temperatura resistivo de platino (PTR, del inglés, Platinum Resistance Thermometer y sensores de temperatura semiconductores de tecnología superficial adheridos con resinas. En otra realización del segundo aspecto de la presente invención, el dispositivo tal y como se ha descrito anteriormente además comprende un transductor del potencial de reducción a una señal eléctrica y medios de detección de dicha señal eléctrica. In another embodiment of the second aspect of the present invention, the device as described above further comprises a temperature sensor. This temperature sensor can be a thermocouple, an NTC thermistor (Negative Temperature Coafficiení), a PTC thermistor (Positive Temparature Coeffícient), a platinum resistive temperature detector (PTR), Platinum Resistance Thermometer and semiconductor temperature sensors surface adhered with resins In another embodiment of the second aspect of the present invention, the device as described above further comprises a transducer of the reduction potential to an electrical signal and means for detecting said electrical signal.
Un tercer aspecto de la presente invención, se refiere a un procedimiento de obtención de un sensor, tal y como se ha descrito anteriormente, que comprende las siguientes etapas: a) depositar de la pista de conductor eléctrico sobre un soporte dieléctrico; A third aspect of the present invention relates to a method of obtaining a sensor, as described above, comprising the following steps: a) depositing the electric conductor track on a dielectric support;
b) sobre la pista de conductor eléctrico obtenida en la etapa (a), depositar de un óxido metálico de un metal M, donde M es un metal que puede presentar al menos dos estados de oxidación, b) on the electric conductor track obtained in step (a), depositing a metal oxide of a metal M, where M is a metal that can have at least two oxidation states,
donde el potencial de reducción entre dichos estados de oxidación varía con el pH,  where the potential for reduction between these oxidation states varies with the pH,
caracterizado porque M no forma especies solubles a pH > 7;  characterized in that M does not form soluble species at pH> 7;
c) recubrir parcial de la pista de conductor eléctrico; y c) partially cover the electric conductor track; Y
d) recubrir del óxido metálico con un polímero hidrogel. d) coating the metal oxide with a hydrogel polymer.
Las etapas (a), (b), (c) y (d) pueden realizarse las siguientes técnicas: Pulverización catódica (sputtering, en inglés) es un proceso físico en el que se produce la vaporización de los átomos de un material sólido denominado "blanco" mediante el bombardeo de éste por iones energéticos. Stages (a), (b), (c) and (d) can perform the following techniques: Sputtering is a physical process in which it occurs the vaporization of the atoms of a solid material called "white" by bombarding it by energy ions.
Serigrafía (screen-printing, en inglés) es una técnica de impresión empleada sobre cualquier material, y consiste en transferir una tinta a través de una malla tensada en un marco. Screen printing (screen-printing, in English) is a printing technique used on any material, and consists of transferring an ink through a tensioned mesh in a frame.
Spray-coating: técnica utilizada en la fabricación de componentes que consiste en proyectar pequeñas partículas, con una boquilla, a modo de spray. Spray-coating: technique used in the manufacture of components that consists of projecting small particles, with a nozzle, as a spray.
Huecograbado (gravure, en inglés) es una técnica que utiliza un cilindro de impresión, que consta básicamente de un cilindro metálico, una capa de cobre sobre la que se grabará el motivo a ser impreso, habitual en soportes flexibles. Esta técnica requiere que lo que se va a depositar sea flexible. Huecogravure (gravure, in English) is a technique that uses a printing cylinder, which basically consists of a metallic cylinder, a layer of copper on which the motif to be printed will be engraved, usually on flexible supports. This technique requires that what is to be deposited be flexible.
Impresión (ink-jet printing, en inglés) es impresión de tintas, parecido a una impresora. Printing (ink-jet printing, in English) is printing of inks, similar to a printer.
Además también se pueden depositar a mano con un pincel o brocha. En una realización del tercer aspecto de la presente invención, tras depositar el conductor eléctrico sobre el soporte (etapa a) se realiza un tratamiento térmico entre 300°C y 1200°C, preferiblemente entre 600°C y 1000°C y más preferiblemente sobre los 800°C. En una realización del tercer aspecto de la presente invención, el óxido metálico se selecciona de Ru, Ir, Rh, Nb, Ta y cualquiera de sus mezclas, preferiblemente el óxido metálico se selecciona de Ru02, Ir02, Rh02, Nb205, Ta205, y cualquiera de sus mezclas, más preferiblemente el óxido metálico se selecciona de Ru02, Ir02 y cualquiera de sus mezclas, y aún más preferiblemente el óxido metálico es Ru02. In addition they can also be deposited by hand with a brush or brush. In an embodiment of the third aspect of the present invention, after depositing the electrical conductor on the support (step a) a heat treatment is carried out between 300 ° C and 1200 ° C, preferably between 600 ° C and 1000 ° C and more preferably on 800 ° C In an embodiment of the third aspect of the present invention, the metal oxide is selected from Ru, Ir, Rh, Nb, Ta and any of its mixtures, preferably the metal oxide is selected from Ru0 2 , Ir0 2 , Rh0 2 , Nb 2 0 5 , Ta 2 0 5 , and any of its mixtures, more preferably the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures, and even more preferably the metal oxide is Ru0 2 .
El óxido metálico preferiblemente se embebe en una matriz orgánica o inorgánica antes de depositarlo. Una vez depositado, se somete a un tratamiento térmico a para que se adhiera sobre la pista conductora. En una realización del tercer aspecto de la presente invención, el óxido metálico se embebe en una matriz orgánica antes de depositarlo, preferiblemente la matriz orgánica es una matriz polimérica termocurable o fotocurable, más preferiblemente la matriz orgánica se selecciona de polímeros epoxis, poliuretanos, polisiloxanos y cualquiera de sus mezclas. Tras depositarlo sobre el soporte, la matriz orgánica con el óxido metálico embebido se somete a un tratamiento térmico entre 40°C y 150°C, preferiblemente entre 50°C y 100 °C. The metal oxide is preferably embedded in an organic or inorganic matrix before depositing. Once deposited, it is subjected to a heat treatment to adhere to the conductive track. In an embodiment of the third aspect of the present invention, the metal oxide is embedded in an organic matrix before depositing it, preferably the organic matrix is a thermosetting or photocurable polymeric matrix, more preferably the organic matrix is selected from epoxy polymers, polyurethanes, polysiloxanes and any of their mixtures. After depositing it on the support, the organic matrix with the embedded metal oxide is subjected to a heat treatment between 40 ° C and 150 ° C, preferably between 50 ° C and 100 ° C.
En una realización del tercer aspecto de la presente invención, el óxido metálico se embebe en una matriz inorgánica antes de depositarlo. Posteriormente a depositarlo sobre el soporte, la matriz inorgánica con el óxido metálico embebido se somete a un tratamiento térmico entre 500°C y 1200°C, preferiblemente entre 700°C y 900°C. In an embodiment of the third aspect of the present invention, the metal oxide is embedded in an inorganic matrix before depositing it. Subsequently to deposit it on the support, the inorganic matrix with the embedded metal oxide is subjected to a heat treatment between 500 ° C and 1200 ° C, preferably between 700 ° C and 900 ° C.
Sobre el óxido metálico se deposita una capa de polímero hidrogel, que es necesario para retener humedad superficial sobre el óxido y asegurar la respuesta del sensor durante un tiempo largo. Se puede depositar por serigrafía y posteriormente se cura a unos 40-60°C. A layer of hydrogel polymer is deposited on the metal oxide, which is necessary to retain surface moisture on the oxide and ensure the sensor response for a long time. It can be deposited by screen printing and subsequently cured at about 40-60 ° C.
En una realización del tercer aspecto de la presente invención, el polímero hidrogel se selecciona de hidrogeles de poliacrilamida, hidrogeles copolímeros que comprenden poliacrilamida, hidrogeles de poliglicoles, hidrogeles de poliuretano, hidrogeles copolímeros que comprenden poliuretano y cualquiera de sus mezclas, preferiblemente el polímero hidrogel es hidrogel copolímero que comprende poliuretano y más preferiblemente el polímero hidrogel es un poliéter-poliuretano. Sobre el óxido metálico se deposita una capa de polímero hidrogel, que es necesario para retener humedad superficial sobre el óxido y asegurar la respuesta del sensor a largo plazo. Tras depositarlo se cura a unos 40-60°C. In an embodiment of the third aspect of the present invention, the hydrogel polymer is selected from polyacrylamide hydrogels, copolymer hydrogels comprising polyacrylamide, polyglycol hydrogels, polyurethane hydrogels, copolymer hydrogels comprising polyurethane and any mixture thereof, preferably the hydrogel polymer it is a hydrogel copolymer comprising polyurethane and more preferably the hydrogel polymer is a polyether polyurethane. A layer of hydrogel polymer is deposited on the metal oxide, which is necessary to retain surface moisture on the oxide and ensure the long-term sensor response. After depositing it is cured at about 40-60 ° C.
En una realización del tercer aspecto de la presente invención, el conductor eléctrico se selecciona de Pt, Ag, Au, Pd, Al, Cu, Ni o cualquiera de sus mezclas, preferiblemente el conductor eléctrico se selecciona de Pd, Ag y cualquiera de sus mezclas. In an embodiment of the third aspect of the present invention, the electrical conductor is selected from Pt, Ag, Au, Pd, Al, Cu, Ni or any of its mixtures, preferably the electrical conductor is selected from Pd, Ag and any of its mixtures
En una realización del tercer aspecto de la presente invención, la capa dieléctrica es un material dieléctrico inorgánico y se selecciona de borosilicatos, Al203, Zr02), mezclas de borosilicatos con Ti03Ba, mezclas de Al20 con Ti03Ba, mezclas de Zr02 con Ti03Ba y cualquiera de sus mezclas. In an embodiment of the third aspect of the present invention, the dielectric layer is an inorganic dielectric material and is selected from borosilicates, Al 2 0 3 , Zr0 2 ), mixtures of borosilicates with Ti0 3 Ba, mixtures of Al 2 0 with Ti0 3 Ba, mixtures of Zr0 2 with Ti0 3 Ba and any of its mixtures.
En una realización del tercer aspecto de la presente invención, la capa dieléctrica es un material dieléctrico polimérico y se selecciona de acrilonitrilo butadieno estireno (ABS), caucho isobutileno-isopreno, gutapercha, polietileno de alta densidad (del inglés HDPE, high-density polyethylene), poliimida, caucho de neopreno, poliamidas, policarbonato, polipropileno, poliestireno, policloruro de vinilo, silicona, politetrafluoroetileno (PTFE). Preferiblemente la capa dieléctrica es un material dieléctrico polimérico. In an embodiment of the third aspect of the present invention, the dielectric layer is a polymeric dielectric material and is selected from acrylonitrile butadiene styrene (ABS), isobutylene-isoprene rubber, gutta-percha, high density polyethylene (HDPE, high-density polyethylene ), polyimide, neoprene rubber, polyamides, polycarbonate, polypropylene, polystyrene, polyvinylchloride, silicone, polytetrafluoroethylene (PTFE). Preferably the dielectric layer is a polymeric dielectric material.
Un cuarto aspecto de la presente invención se refiere al uso del tal y como se ha definido anteriormente para medir el pH de hormigón. A fourth aspect of the present invention relates to the use thereof as defined above to measure the pH of concrete.
Un quinto aspecto de la presente invención se refiere al uso del dispositivo tal y como se ha descrito anteriormente para medir el pH de hormigón. A fifth aspect of the present invention relates to the use of the device as described above to measure the pH of concrete.
A lo largo de la descripción y las reivindicaciones la palabra "comprende" y sus variantes no pretenden excluir otras características técnicas, aditivos, componentes o pasos. Para los expertos en la materia, otros objetos, ventajas y características de la invención se desprenderán en parte de la descripción y en parte de la práctica de la invención. Los siguientes ejemplos y figuras se proporcionan a modo de ilustración, y no se pretende que sean limitativos de la presente invención. Throughout the description and the claims the word "comprises" and its variants are not intended to exclude other technical characteristics, additives, components or steps. For those skilled in the art, other objects, advantages and features of the invention will be derived partly from the description and partly from the practice of the invention. The following examples and figures are provided by way of illustration, and are not intended to be limiting of the present invention.
BREVE DESCRIPCIÓN DE LAS FIGURAS BRIEF DESCRIPTION OF THE FIGURES
FIG. 1. Variación de potencial en función del tiempo detectado por un sensor de la invención en el interior de un bloque de hormigón. E: Potencial en V; T: tiempo en horas. FIG. 2. Fotografía del avance del frente carbonatado (incoloro) en una probeta de hormigón. FIG. 1. Potential variation as a function of the time detected by a sensor of the invention inside a concrete block. E: Potential in V; T: time in hours. FIG. 2. Photograph of the advance of the carbonated (colorless) front in a concrete specimen.
FIG. 3. Variación de potencial en función del tiempo detectado por un dispositivo que comprende 3 sensores de la invención. E: Potencial en V; T: tiempo en días; t1 , t2 y t3: tiempos de llegada del frente carbonatado para cada uno de los sensores del dispositivo. FIG. 3. Potential variation as a function of the time detected by a device comprising 3 sensors of the invention. E: Potential in V; T: time in days; t1, t2 and t3: arrival times of the carbonated front for each of the sensors of the device.
FIG. 4. Esquema de un dispositivo de la invención que comprende 3 sensores. 1 : soporte; 2 y 3: pista conductora; 3: zona de conexión eléctrica; 4: óxido metálico. FIG. 4. Scheme of a device of the invention comprising 3 sensors. 1: support; 2 and 3: conductive track; 3: electrical connection zone; 4: metal oxide.
EJEMPLOS EXAMPLES
A continuación se ilustrará la invención mediante unos ensayos realizados por los inventores, que pone de manifiesto la efectividad del producto de la invención. The invention will now be illustrated by tests carried out by the inventors, which demonstrates the effectiveness of the product of the invention.
Ejemplo 1. Procedimiento de obtención de un dispositivo de la invención Example 1. Procedure for obtaining a device of the invention
Este ejemplo describe el procedimiento de obtención de un dispositivo que comprende 3 sensores de la invención, ilustrado en la figura 4. This example describes the method of obtaining a device comprising 3 sensors of the invention, illustrated in Figure 4.
Sobre un sustrato de alúmina se depositó el conductor eléctrico para formar las pistas conductoras [2] y la zona de conectores [3]. Estas pistas se obtuvieron mediante tratamiento térmico (800-900°C, 1 h) de la serigrafía de una pasta de Ag/Pd. The electrical conductor was deposited on an alumina substrate to form the conductive tracks [2] and the connector area [3]. These tracks were obtained by heat treatment (800-900 ° C, 1 h) of the screen printing of an Ag / Pd paste.
El sistema sensor dispone de una zona terminal [3] para el conexionado eléctrico al equipo lector de la información. The sensor system has a terminal zone [3] for the electrical connection to the information reading equipment.
Posteriormente, en el reverso se serigrafían las pistas conductoras de los sensores de temperatura y se aplica el mismo tratamiento térmico. Subsequently, the conductive tracks of the temperature sensors are screen printed on the reverse and the same heat treatment is applied.
Sobre las pistas conductoras se depositó a continuación el óxido de rutenio (Ru02) [4]. Tras un tratamiento térmico (quemado a unos 700°C) se eliminó el vehículo orgánico (terpineol-butanol) a la vez que se adhirió y estabiliza el óxido metálico sobre la pista conductora. Ruthenium oxide (Ru0 2 ) [4] was then deposited on the conductive tracks. After a heat treatment (burned at about 700 ° C), the organic vehicle (terpineol-butanol) was removed while adhering and stabilizing the metal oxide on the conductive track.
Posteriormente se añadió una capa dieléctrica que es un polímero dieléctrico (D- GWENT D50706P3) recubriendo las distintas pistas conductoras pero dejando libre la superficie activa del óxido sensor y la zona del conexionado eléctrico. El curado de este dieléctrico se sitúa alrededor de los 100°C. Montaje de sensores de temperatura en tecnología de montaje superficial y posterior protección con un gel tipo elastómero que evita la humedad sobre los sensores. Subsequently, a dielectric layer was added which is a dielectric polymer (D-GWENT D50706P3) covering the different conductive tracks but leaving the active surface of the sensor oxide and the area of the electrical connection free. The curing of this dielectric is around 100 ° C. Temperature sensor assembly in surface mount technology and subsequent protection with an elastomeric gel that prevents moisture on the sensors.
Sobre el elemento sensor de óxido metálico se depositó una membrana hidrofílica. La membrana hidrofílica empleada se preparó disolviendo 500 mg del gel comercial de HydroMed D4, que es un poliéter-poliuretano con un contenido de agua aproximado de 50%, disuelto en 5,4 gramos de alcohol etílico al que se han añadido 0,5 mi de agua destilada. La mezcla se introduce en un tubo dentro del ultrasonidos durante 5 minutos. La disolución resultante se deposita con un cuentagotas sobre los elementos sensores de óxido de rutenio y se deja secar en estufa a 40°C. La dosificación de hidrogel se puede aplicar varias veces consecutivas para aumentar el espesor de la capa hidrofílica. A hydrophilic membrane was deposited on the metal oxide sensor element. The hydrophilic membrane used was prepared by dissolving 500 mg of the commercial HydroMed D4 gel, which is a polyether polyurethane with an approximate water content of 50%, dissolved in 5.4 grams of ethyl alcohol to which 0.5 ml has been added. of distilled water. The mixture is introduced into a tube inside the ultrasound for 5 minutes. The resulting solution is deposited with a dropper on the sensor elements of ruthenium oxide and allowed to dry in an oven at 40 ° C. The hydrogel dosage can be applied several consecutive times to increase the thickness of the hydrophilic layer.
Ejemplo 2. Medición de pH en hormigón Example 2. Measurement of pH in concrete
El sensor del ejemplo 1 se colocó en la zona de recubrimiento de las armaduras, antes del hormigonado de la estructura. En el momento que un sensor detecta el avance del frente carbonatado (bajada de pH), se produce una variación importante del potencial del electrodo, directamente proporcional a la variación de pH producida (Fig. 1). The sensor of example 1 was placed in the area of the reinforcement covering, before concreting the structure. At the moment that a sensor detects the advance of the carbonated front (lowering of pH), there is an important variation of the electrode potential, directly proportional to the variation of pH produced (Fig. 1).
En la fig. 2 se muestra una fotografía del avance del frente carbonatado (zona incolora en una muestra de hormigón con fenolftaleína). In fig. 2 shows a photograph of the advance of the carbonated front (colorless area in a concrete sample with phenolphthalein).
Dado que el dispositivo puede estar compuesto por varios sensores situados a distintas distancias de la superficie de hormigón, además de la profundidad del frente carbonatado es posible conocer la velocidad de avance. En la fig. 3 se muestra una gráfica que ilustra la variación de potencial con el tiempo de tres sensores colocados a diferentes distancias. Como la distancia entre la superficie del hormigón y el primer sensor es conocida, así como las distancias entre los distintos sensores, conociendo los tiempos que tardan los distintos sensores en empezar a variar su potencial se puede automáticamente saber a qué velocidad avanza el frente carbonatado. Una ventaja del dispositivo que comprende más de un sensor, donde la distancia entre los sensores está bien definida, es que la distancia entre el primer sensor y la superficie del hormigón no es normalmente un dato preciso, debido al proceso de ejecución en una obra, sin embargo, las distancias entre los distintos sensores del dispositivo sí que es un valor que se conoce con total precisión. Since the device can be composed of several sensors located at different distances from the concrete surface, in addition to the depth of the carbonated front it is possible to know the forward speed. In fig. 3 shows a graph that illustrates the potential variation over time of three sensors placed at different distances. As the distance between the surface of the concrete and the first sensor is known, as well as the distances between the different sensors, knowing the times it takes for the different sensors to begin to vary their potential, you can automatically know at what speed the carbonated front advances. An advantage of the device comprising more than one sensor, where the distance between the sensors is well defined, is that the distance between the first sensor and the surface of the concrete is not normally a precise data, due to the process of execution in a work, however, the distances between the different sensors of the device itself is a value that is known with total precision.

Claims

REIVINDICACIONES
1. - Sensor de pH que comprende: a) una pista de un conductor eléctrico; 1. - pH sensor comprising: a) a track of an electric conductor;
b) sobre la pista de conductor eléctrico, un óxido metálico de al menos un metal M, donde M es un metal que presenta al menos dos estados de oxidación, donde el potencial de reducción entre dichos estados de oxidación varía con el pH; b) on the electric conductor track, a metal oxide of at least one metal M, where M is a metal that has at least two oxidation states, where the potential for reduction between said oxidation states varies with the pH;
c) una capa de material dieléctrico que cubre parcialmente la pista del conductor eléctrico; y c) a layer of dielectric material that partially covers the track of the electric conductor; Y
d) medios para conexión eléctrica; caracterizado porque M no forma especies solubles a pH > 7; y d) means for electrical connection; characterized in that M does not form soluble species at pH> 7; Y
porque el óxido metálico está recubierto de un polímero hidrogel. because the metal oxide is coated with a hydrogel polymer.
2. - El sensor según la reivindicación anterior, donde el óxido metálico se selecciona de óxidos de Ru, Ir, Rh, Nb, Ta y cualquiera de sus mezclas. 2. - The sensor according to the preceding claim, wherein the metal oxide is selected from oxides of Ru, Ir, Rh, Nb, Ta and any of their mixtures.
3. - El sensor según cualquiera de las reivindicaciones 1 o 2, donde el óxido metálico se selecciona de Ru02, Ir02, Rh02, Nb205, Ta205 y cualquiera de sus mezclas. 3. - The sensor according to any of claims 1 or 2, wherein the metal oxide is selected from Ru0 2 , Ir0 2 , Rh0 2 , Nb 2 0 5 , Ta 2 0 5 and any of their mixtures.
4. - El sensor según la reivindicación anterior, donde el óxido metálico se selecciona de Ru02, Ir02 y cualquiera de sus mezclas. 4. - The sensor according to the preceding claim, wherein the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures.
5.- El sensor según cualquiera de las reivindicaciones anteriores, donde el óxido metálico está embebido en una matriz orgánica. 5. The sensor according to any of the preceding claims, wherein the metal oxide is embedded in an organic matrix.
6. - El sensor según la reivindicación anterior, donde la matriz orgánica se selecciona de polímeros epoxis, poliuretanos, polisiloxanos y cualquiera de sus mezclas. 6. - The sensor according to the preceding claim, wherein the organic matrix is selected from epoxy polymers, polyurethanes, polysiloxanes and any of their mixtures.
7. - El sensor según cualquiera de las reivindicaciones 1 a 4, donde el óxido metálico está embebido en una matriz vitrea inorgánica. 7. - The sensor according to any of claims 1 to 4, wherein the metal oxide is embedded in an inorganic vitreous matrix.
8. - El sensor según la reivindicación anterior, donde la matriz vitrea inorgánica se selecciona de borosilicatos, boratos o cualquiera de sus mezclas. 8. - The sensor according to the preceding claim, wherein the inorganic vitreous matrix is selected from borosilicates, borates or any of their mixtures.
9.- El sensor según cualquiera de las reivindicaciones 5 a 8, donde el ratio en peso de óxido metálico:matriz orgánica o inorgánica es de 4: 1 a 1 :4. 9. The sensor according to any of claims 5 to 8, wherein the weight ratio of metal oxide: organic or inorganic matrix is 4: 1 to 1: 4.
10. - El sensor según cualquiera de las reivindicaciones anteriores, donde el polímero hidrogel se selecciona de hidrogeles de poliacrilamida, hidrogeles copolímeros que comprenden poliacrilamida, hidrogeles de poliglicoles, hidrogeles de poliuretano, hidrogeles copolímeros que comprenden poliuretano y cualquiera de sus mezclas. 10. - The sensor according to any of the preceding claims, wherein the hydrogel polymer is selected from polyacrylamide hydrogels, copolymer hydrogels comprising polyacrylamide, polyglycol hydrogels, polyurethane hydrogels, copolymer hydrogels comprising polyurethane and any mixture thereof.
1 1. - El sensor según cualquiera de las reivindicaciones anteriores donde el polímero hidrogel es hidrogel copolímero que comprende poliuretano, preferiblemente el polímero hidrogel es un poliéter-poliuretano. The sensor according to any of the preceding claims wherein the hydrogel polymer is hydrogel copolymer comprising polyurethane, preferably the hydrogel polymer is a polyether polyurethane.
12. - El sensor según cualquiera de las reivindicaciones anteriores, donde el conductor eléctrico se selecciona de Pt, Ag, Au, Pd, Al, Cu, Ni o cualquiera de sus mezclas. 12. - The sensor according to any of the preceding claims, wherein the electrical conductor is selected from Pt, Ag, Au, Pd, Al, Cu, Ni or any of its mixtures.
13. - El sensor según cualquiera de las reivindicaciones anteriores, donde el conductor eléctrico se selecciona de Pd, Ag y cualquiera de sus mezclas. 13. - The sensor according to any of the preceding claims, wherein the electrical conductor is selected from Pd, Ag and any of its mixtures.
14. - El sensor según cualquiera de las reivindicaciones anteriores, donde la capa dieléctrica es un material dieléctrico inorgánico y se selecciona de borosilicatos, Al203,14. - The sensor according to any of the preceding claims, wherein the dielectric layer is an inorganic dielectric material and is selected from borosilicates, Al 2 0 3 ,
Zr02), mezclas de borosilicatos con Ti03Ba, mezclas de Al20 con Ti03Ba, mezclas de Zr02 con Ti03Ba y cualquiera de sus mezclas. Zr0 2 ), mixtures of borosilicates with Ti0 3 Ba, mixtures of Al 2 0 with Ti0 3 Ba, mixtures of Zr0 2 with Ti0 3 Ba and any of their mixtures.
15. - El sensor según cualquiera de las reivindicaciones 1 a 13, donde la capa dieléctrica es un material dieléctrico polimérico y se selecciona de acrilonitrilo butadieno estireno (ABS), caucho isobutileno-isopreno, gutapercha, polietileno de alta densidad (del inglés HDPE, high-density polyethylene), poliimida, caucho de neopreno, poliamidas, policarbonato, polipropileno, poliestireno, policloruro de vinilo, silicona, politetrafluoroetileno (PTFE). 15. - The sensor according to any of claims 1 to 13, wherein the dielectric layer is a polymeric dielectric material and is selected from acrylonitrile butadiene styrene (ABS), isobutylene-isoprene rubber, gutta-percha, high density polyethylene (English HDPE, high-density polyethylene), polyimide, neoprene rubber, polyamides, polycarbonate, polypropylene, polystyrene, polyvinylchloride, silicone, polytetrafluoroethylene (PTFE).
16. - Dispositivo que comprende al menos un sensor según las reivindicaciones 1 a 15. 16. - Device comprising at least one sensor according to claims 1 to 15.
17.- Dispositivo que comprende al menos dos sensores según las reivindicaciones 1 a 15. 17. Device comprising at least two sensors according to claims 1 to 15.
18.- Dispositivo según cualquiera de las reivindicaciones 16 o 17, que además comprende un sensor de temperatura. 18. Device according to any of claims 16 or 17, further comprising a temperature sensor.
19.- Dispositivo según cualquiera de las reivindicaciones 16 a 18 que comprende un transductor del potencial de reducción a una señal eléctrica y medios de detección de dicha señal eléctrica. 19. Device according to any of claims 16 to 18 comprising a transducer of the reduction potential to an electrical signal and means for detecting said electrical signal.
20. - Procedimiento de obtención de un sensor según las reivindicaciones 1 a 15 que comprende las siguientes etapas: a) depositar de una pista de conductor eléctrico sobre un soporte dieléctrico; 20. - Method of obtaining a sensor according to claims 1 to 15 comprising the following steps: a) depositing an electric conductor track on a dielectric support;
b) sobre la pista de conductor eléctrico obtenida en la etapa (a), depositar de un óxido metálico de un metal M, donde M es un metal que puede presentar al menos dos estados de oxidación, b) on the electric conductor track obtained in step (a), depositing a metal oxide of a metal M, where M is a metal that can have at least two oxidation states,
donde el potencial de reducción entre dichos estados de oxidación varía con el pH,  where the potential for reduction between these oxidation states varies with the pH,
caracterizado porque M no forma especies solubles a pH > 7;  characterized in that M does not form soluble species at pH> 7;
c) recubrir parcial de la pista de conductor eléctrico; y c) partially cover the electric conductor track; Y
d) recubrir del óxido metálico con un polímero hidrogel. d) coating the metal oxide with a hydrogel polymer.
21. - El procedimiento según la reivindicación anterior, donde el óxido metálico se selecciona de óxidos de Ru, Ir, Rh, Nb, Ta y cualquiera de sus mezclas. 21. - The process according to the preceding claim, wherein the metal oxide is selected from oxides of Ru, Ir, Rh, Nb, Ta and any of their mixtures.
22. - El procedimiento según cualquiera de las reivindicaciones 20 o 21 donde el óxido metálico se selecciona de Ru02, Ir02, Rh02, Nb205, Ta205, y cualquiera de sus mezclas. 22. - The process according to any of claims 20 or 21 wherein the metal oxide is selected from Ru0 2 , Ir0 2 , Rh0 2 , Nb 2 0 5 , Ta 2 0 5 , and any of their mixtures.
23. - El procedimiento según cualquiera de las reivindicaciones 20 a 22, donde el óxido metálico se selecciona de Ru02, Ir02 y cualquiera de sus mezclas. 23. - The process according to any of claims 20 to 22, wherein the metal oxide is selected from Ru0 2 , Ir0 2 and any of its mixtures.
24. - El procedimiento según cualquiera de las reivindicaciones 20 a 23, donde antes de depositar del óxido metálico de la etapa (b) el óxido metálico se embebe en una matriz orgánica. 24. - The method according to any of claims 20 to 23, wherein before depositing the metal oxide of step (b) the metal oxide is embedded in an organic matrix.
25.- El procedimiento según la reivindicación anterior, donde la matriz orgánica se selecciona de polímeros epoxis, poliuretanos, polisiloxanos y cualquiera de sus mezclas. 25. The method according to the preceding claim, wherein the organic matrix is Select from epoxy polymers, polyurethanes, polysiloxanes and any of their mixtures.
26. - El procedimiento según cualquiera de las reivindicaciones 20 a 23, donde antes de depositar del óxido metálico de la etapa (b) el óxido metálico se embebe en una matriz vitrea inorgánica. 26. - The method according to any of claims 20 to 23, wherein before depositing the metal oxide of step (b) the metal oxide is embedded in an inorganic vitreous matrix.
27. - El procedimiento según la reivindicación anterior, donde la matriz vitrea inorgánica se selecciona de borosilicatos, boratos o cualquiera de sus mezclas. 27. - The method according to the preceding claim, wherein the inorganic vitreous matrix is selected from borosilicates, borates or any of their mixtures.
28. - El procedimiento según cualquiera de las reivindicaciones 20 a 27, donde el polímero hidrogel se selecciona de hidrogeles de poliacrilamida, hidrogeles copolímeros que comprenden poliacrilamida, hidrogeles de poliglicoles, hidrogeles de poliuretano, hidrogeles copolímeros que comprenden poliuretano y cualquiera de sus mezclas. 28. The method according to any of claims 20 to 27, wherein the hydrogel polymer is selected from polyacrylamide hydrogels, copolymer hydrogels comprising polyacrylamide, polyglycol hydrogels, polyurethane hydrogels, copolymer hydrogels comprising polyurethane and any mixture thereof.
29. - El procedimiento según cualquiera de las reivindicaciones 20 a 28, donde el polímero hidrogel es hidrogel copolímero que comprende poliuretano. 29. - The process according to any of claims 20 to 28, wherein the hydrogel polymer is hydrogel copolymer comprising polyurethane.
30.- El procedimiento según cualquiera de las reivindicaciones 20 a 29, donde el conductor eléctrico se selecciona de Pt, Ag, Au, Pd, Al, Cu, Ni o cualquiera de sus mezclas. 30. The method according to any of claims 20 to 29, wherein the electric conductor is selected from Pt, Ag, Au, Pd, Al, Cu, Ni or any of its mixtures.
31. - El procedimiento según cualquiera de las reivindicaciones 20 a 30 donde el conductor eléctrico se selecciona de Pd, Ag y cualquiera de sus mezclas. 31. - The method according to any of claims 20 to 30 wherein the electric conductor is selected from Pd, Ag and any of its mixtures.
32. - El procedimiento según cualquiera de las reivindicaciones 20 a 31 , donde la capa dieléctrica es un material dieléctrico inorgánico y se selecciona de borosilicatos, Al203, Zr02), mezclas de borosilicatos con Ti03Ba, mezclas de Al20 con Ti03Ba, mezclas de Zr02 con Ti03Ba y cualquiera de sus mezclas. 32. - The method according to any of claims 20 to 31, wherein the dielectric layer is an inorganic dielectric material and is selected from borosilicates, Al 2 0 3 , Zr0 2 ), mixtures of borosilicates with Ti0 3 Ba, mixtures of Al 2 0 with Ti0 3 Ba, mixtures of Zr0 2 with Ti0 3 Ba and any of its mixtures.
33. - El procedimiento según cualquiera de las reivindicaciones 20 a 31 , donde la capa dieléctrica es un material dieléctrico polimérico y se selecciona de acrilonitrilo butadieno estireno (ABS), caucho isobutileno-isopreno, gutapercha, polietileno de alta densidad (del inglés HDPE, high-density polyethylene), poliimida, caucho de neopreno, poliamidas, policarbonato, polipropileno, poliestireno, policloruro de vinilo, silicona, politetrafluoroetileno (PTFE). 33. The method according to any of claims 20 to 31, wherein the dielectric layer is a polymeric dielectric material and is selected from acrylonitrile butadiene styrene (ABS), isobutylene-isoprene rubber, gutta-percha, high density polyethylene (HDPE, high-density polyethylene), polyimide, neoprene rubber, polyamides, polycarbonate, polypropylene, polystyrene, polyvinylchloride, silicone, polytetrafluoroethylene (PTFE).
34. - Uso del sensor según cualquiera de las reivindicaciones 1 a 15 para medir el pH de hormigón. 34. - Use of the sensor according to any one of claims 1 to 15 to measure the pH of concrete.
35. - Uso del dispositivo según cualquiera de las reivindicaciones 16 a 19 para medir el pH de hormigón. 35. - Use of the device according to any of claims 16 to 19 to measure the pH of concrete.
PCT/ES2015/070678 2014-09-19 2015-09-18 Sensor for determining the depth and speed of carbonation of cement WO2016042195A1 (en)

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ES201431359A ES2518065B2 (en) 2014-09-19 2014-09-19 Sensor for the determination of the depth and speed of carbonation of concrete

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Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
BERTOLINI L ET AL.: "Corrosion behaviour of steel in concrete in the presence of stray current.", CORROSION SCIENCE, vol. 49, no. 3, 28 February 2007 (2007-02-28), pages 1056 - 1068, XP005793471, ISSN: 0010-938X, DOI: doi:10.1016/j.corsci.2006.05.048 *
DUFFO G S ET AL.: "Characterization of solid embeddable reference electrodes for corrosion monitoring in reinforced concrete structures.", ELECTROCHIMICA ACTA, vol. 54, no. 3, 1 January 2009 (2009-01-01), pages 1010 - 1020, XP025762217, ISSN: 0013-4686, DOI: doi:10.1016/j.electacta.2008.08.025 *
KURZWEIL P: "Metal oxides and ion-exchanging surfaces as pH sensors in liquids: State-of-the-art and outlook.", SENSORS, vol. 9, no. 6, 31 May 2009 (2009-05-31), pages 4955 - 4985, XP055176863, ISSN: 1424-8220, DOI: doi:10.3390/s90604955 *
MURALIDHARAN S ET AL.: "Electrochemical studies on the performance characteristics of solid metal-metal oxide reference sensor for concrete environments.", SENSORS AND ACTUATORS, B: CHEMICAL 20060117, vol. 113, no. 1, 17 January 2006 (2006-01-17), pages 187 - 193, XP025111711, ISSN: 0925-4005, DOI: doi:10.1016/j.snb.2005.02.052 *

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