WO2011015689A2 - Cementitious composite with carbon nanofibers for monitoring deformations - Google Patents
Cementitious composite with carbon nanofibers for monitoring deformations Download PDFInfo
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- WO2011015689A2 WO2011015689A2 PCT/ES2010/000341 ES2010000341W WO2011015689A2 WO 2011015689 A2 WO2011015689 A2 WO 2011015689A2 ES 2010000341 W ES2010000341 W ES 2010000341W WO 2011015689 A2 WO2011015689 A2 WO 2011015689A2
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- composite
- cement
- monitoring
- cementitious
- deformation
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Classifications
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/022—Carbon
- C04B14/026—Carbon of particular shape, e.g. nanotubes
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/38—Fibrous materials; Whiskers
- C04B14/386—Carbon
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0041—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0083—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by measuring variation of impedance, e.g. resistance, capacitance, induction
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/90—Electrical properties
- C04B2111/94—Electrically conducting materials
Definitions
- the present invention falls within the field of construction, and more particularly refers to materials technology and nanotechnology.
- REPLACEMENT SHEET (Rule 26) complex and very delicate at the time of obtaining the desired results since it implies the use of additional additives and several stages prior to the incorporation into the matrix itself.
- Carbon fiber offers a moderate area of contact with the cementitious matrix, a property that is important when the material works.
- the matrix-nanofiber contact area is much larger than that presented by the carbon fiber material, which translates into a greater sensitivity of the composite.
- the electrical properties are achieved by conductive additions such as carbonaceous materials (for example, graphite powder, carbon fibers or
- This invention raises the feasibility of the use of carbon nanofibers in cementitious matrices: pastes, mortars and concretes, in order to use said composites in the deformation monitoring, that is to say detecting their own deformation when being subjected to external actions without any type of embedded or attached sensor.
- This innovative procedure is based on the change in the electrical resistance of the cementitious material with the addition of carbon nanofibers when subjected to stresses. In this way, a proportional change of the contact resistance of the matrix with the nanofiber is made with the level of stresses to which it is subjected, which is undoubtedly interesting when talking about an intelligent structure.
- the function of perception of the deformation by adding carbon nanofibers is that by subjecting the material to compression, this contact resistance between the cement matrix and the nanofiber decreases, producing in turn the decrease of the overall electrical resistance in the effort direction. While the tension applied is tensile, the phenomenon generated is the opposite.
- Figure 1 shows a prismatic specimen with dimensions 4x4x16 cm.
- This test tube used in the invention is made of cement paste
- Portland and carbon nanofiber of the stacked-cup type with an outside diameter that varies between 20 and 80 nm and a large central hole. These nanofibers have a very high aspect ratio, with a length of several microns.
- the measurement method consists in introducing the current through the upper face 1 and the lower face 2 of the specimen and the potential difference was taken between points 3 and 4. From the potential drop values between points 3 and
- Figure 2 shows an example of the behavior of the invention where the evolution of the electrical resistance as a function of the deformation during an axial compression test is shown.
- 4x4x16 cm specimen of cement paste with 5% carbon nanofiber addition 4000N load amplitude and 100 N / s speed.
- Figure 3 shows the relationship between the unit increase in electrical resistance and the unit deformation in an axial compression test.
- the invention consists in the use of carbon nanofibers in cementitious matrices: pastes, mortars and concrete, with the aim of developing the function of perception of the deformation and thus being able to detect its own deformation when subjected to external actions without any sensor
- prismatic specimens of dimensions 4x4x16 cm with Portland cement paste and carbon nanofiber of the stacked-cup type have been considered, with an outside diameter that varies between 20 and 80 nm and a large central hole.
- These nanofibers have a very high aspect ratio, with a length of several microns.
- the basic components used have been:
- the specimens were cured submerged in water for 28 days before being tested.
- the loading of the specimens was carried out by means of an electromechanical press model EMI / 100 / FR, supplied by Microtest S.A.
- the electrical resistance was measured thanks to a Keithley 2002 digital multimeter supplied by National Instruments Inc.
- the current was applied using a Keithley 6021 external source supplied by National Instruments Inc.
- REPLACEMENT SHEET (Rule 26) The different tests carried out consisted of monitoring the electrical resistance of the specimen in the longitudinal direction while applying compression cycles also longitudinally.
- the maximum load value applied in each cycle was 4 kN, this value corresponds to less than 25% of the breaking load of the composite material, being located at an intermediate point within the elastic deformation zone of the composite, in which The behavior is optimal and reversible.
- the loading and unloading speed was 100 N / s since a faster accelerated load produces effects similar to impacts, which would result in irreversible damage to the composite. Lower values of loading speed excessively extend the material test.
- the current intensity applied was 0.1mA since higher values would produce the polarization of the interstitial solution of the composite (which masks the measurement), also avoiding undesirable electrochemical reactions on the electrodes that also affect the composite and the deformation monitoring. Lower current values significantly reduced the sensitivity of the composite to the test performed.
- the level of perception of the deformation is characterized by the gauge factor (FG).
- This parameter is defined as the fractional change of the resistivity per unit of deformation ( ⁇ ).
- FG gauge factor
- ⁇ fractional change of the resistivity per unit of deformation
- FG is the gauge factor
- ⁇ p is the variation of resistivity [ohm-cm]
- p is the initial resistivity [ohm-cm]
- REPLACEMENT SHEET (Rule 26) extensometric on the surface of the specimens.
- the measurement method consists in introducing the current between the upper faces
- the variation of the corresponding resistivities is calculated.
- the deformation was calculated as the average of the values recorded by four strain gauges that were located at the central point of each of the side faces of the specimens, in order to have a more reliable value of the actual deformation during the test. loading
- the specimens used in these tests were stored in an environment with 100% relative humidity until their weight stabilized.
- the initial resistivity of the specimens was approximately 1575 ohm cm.
- Figure 2 shows the evolution of the electrical resistance of a cement paste specimen with a 5% addition of carbon nanofiber with the deformation that said specimen undergoes when subjected to an axial compression stress. This proportion of nanofiber was used since after initial studies, the optimum behavior of the composite from the point of view of the deformation monitoring was obtained for this amount. Negative deformations correspond to compressions of the specimen. As can be seen, there is a clear relationship between both parameters, as the test piece is compressed there is a decrease in its electrical resistance, which allows the possibility of establishing a relationship between both parameters.
- REPLACEMENT SHEET (Rule 26) have a good reliability in the function of perception of the deformation.
- the specimen used is 4x4x16 cm of cement paste with 5% carbon nanofiber addition, 4000N load amplitude and 100 N / s speed.
- Figure 3 shows the relationship between the unit increase in electrical resistance and the unit deformation in an axial compression test. Cement paste test tube with 5% carbon nanofiber addition. The parameter that characterizes the sensitivity of the deformation perception function is obtained from the slope of said relationship.
Abstract
The invention proposes the viability of using carbon nanofibers for cement moulds such as pastes, mortars, and concretes, with the purpose of using such composites to monitor deformations in order to detect the deformation thereof due to external activities with no sensor embedded or attached. The procedure is based on changing the electrical resistance of the carbon nanofiber/cement composites when subjected to stress. A proportional change is made to the contact stress of the matrix with the nanofiber and the level of stresses to which it is subjected; this is undoubtedly interesting when talking about an intelligent structure. The composite is adaptable to control structural vibrations, heavy traffic monitoring, movement detection in building areas, and building security in real time, amongst others.
Description
COMPOSITE CEMENTICIO CON NANOFIBRAS DE CARBONO PARA MONITORIZACIÓN DE DEFORMACIONES COMPOSITE CEMENTICIO WITH CARBON NANOFIBERS FOR MONITORING DEFORMATIONS
DESCRIPCIÓN DESCRIPTION
Composite cementicio con nanofibras de carbono para monitorización de deformaciones Cementitious composite with carbon nanofibers for deformation monitoring
Campo de Ia invención Field of the invention
La presente invención se encuadra en el campo de Ia construcción, y más particularmente se refiere a tecnología de los materiales y nanotecnología. The present invention falls within the field of construction, and more particularly refers to materials technology and nanotechnology.
Antecedentes de Ia invención Background of the invention
La función de percepción de Ia deformación fue desarrollada inicialmente utilizando fibras de acero y fibras de carbono de uso general, siendo objeto de estudio con creciente interés hasta el presente con Ia introducción de nuevos parámetros. The function of perception of the deformation was initially developed using steel fibers and carbon fibers of general use, being studied with increasing interest until now with the introduction of new parameters.
En Ia década de los noventa se patentaron diversos procedimientos para aplicar esta técnica. Entre los antecedentes conocidos destacan las patentes americanas US5817944 y US6079277. Tales invenciones consisten en el uso de fibras de carbono dispersadas en matrices de cemento para medir Ia deformación que sufren al ser sometidas a un esfuerzo externo sin necesidad de llevar ningún sensor embebido o adherido, mediante Ia medida de las variaciones de su resistencia eléctrica durante el proceso. In the 1990s, several procedures were patented to apply this technique. Among the known background are US patents US5817944 and US6079277. Such inventions consist of the use of carbon fibers dispersed in cement matrices to measure the deformation they suffer when subjected to external stress without the need to carry any embedded or adhered sensors, by measuring the variations of their electrical resistance during the process.
Los principales inconvenientes que plantean estos antecedentes son: • La dispersión de estas adiciones en Ia matriz cementicia es una labor The main disadvantages of this background are: • The dispersion of these additions in the cement matrix is a task
HOJA DE REEMPLAZO (Regla 26)
compleja y muy delicada a Ia hora de obtener los resultados deseados ya que implica el uso de aditivos adicionales y varias etapas previas a Ia propia incorporación a Ia matriz. REPLACEMENT SHEET (Rule 26) complex and very delicate at the time of obtaining the desired results since it implies the use of additional additives and several stages prior to the incorporation into the matrix itself.
• La fibra de carbono ofrece una moderada área de contacto con Ia matriz cementicia, propiedad que es importante a Ia hora de que el material funcione. • Carbon fiber offers a moderate area of contact with the cementitious matrix, a property that is important when the material works.
Con Ia intención de mejorar tales inconvenientes surge esta invención que ofrece las siguientes mejoras respecto a los materiales que emplean fibras de carbono: With the intention of improving such inconveniences, this invention arises which offers the following improvements with respect to materials that use carbon fibers:
• La incorporación de nanofibras en Ia matrices cementicias es un proceso sencillo y reproducible ya que su dispersión en Ia matriz es directa, Io cual garantiza poder llevar a cabo Ia monitorización de Ia deformación de forma óptima. • The incorporation of nanofibers in cementitious matrices is a simple and reproducible process since its dispersion in the matrix is direct, which guarantees that the deformation monitoring can be carried out optimally.
• El área de contacto matriz-nanofibra es muy superior a Ia que presenta el material con fibra de carbono, Io cual se traduce en una mayor sensibilidad del composite. • The matrix-nanofiber contact area is much larger than that presented by the carbon fiber material, which translates into a greater sensitivity of the composite.
Explicación de Ia invención Explanation of the invention
Tradicionalmente Ia línea de investigación de los materiales cementicios empleados en obra civil y edificación ha estado orientada al estudio de sus propiedades mecánicas debido a su principal y única función estructural. No obstante, últimamente ha surgido una nueva tendencia en esta línea; Ia integración de otras propiedades que Ie permitan tener funciones complementarias, convirtiéndose en materiales "multifuncionales". Existen diversas categorías dentro de los materiales cementicios "multifuncionales"; una de ellas son los materiales cementicios conductores. Traditionally, the line of investigation of cementitious materials used in civil works and construction has been oriented to the study of their mechanical properties due to their main and only structural function. However, lately there has been a new trend in this line; The integration of other properties that allow it to have complementary functions, becoming "multifunctional" materials. There are various categories within "multifunctional" cementitious materials; One of them are conductive cementitious materials.
Las propiedades eléctricas se consiguen mediante adiciones conductoras como los materiales carbonosos (por ejemplo, polvo de grafito, fibras de carbono o The electrical properties are achieved by conductive additions such as carbonaceous materials (for example, graphite powder, carbon fibers or
HOJA DE REEMPLAZO (Regla 26)
nanofibras de carbono). REPLACEMENT SHEET (Rule 26) carbon nanofibers).
Esta invención plantea Ia viabilidad del uso de nanofibras de carbono en matrices cementicias: pastas, morteros y hormigones, a fin de usar dichos composites en Ia monitorización de deformaciones, es decir de detectar su propia deformación al verse sometidos a acciones externas sin ningún tipo de sensor embebido o adherido. This invention raises the feasibility of the use of carbon nanofibers in cementitious matrices: pastes, mortars and concretes, in order to use said composites in the deformation monitoring, that is to say detecting their own deformation when being subjected to external actions without any type of embedded or attached sensor.
Este procedimiento innovador se basa en el cambio en Ia resistencia eléctrica del material cementicio con adición de nanofibras de carbono al ser sometida a tensiones. De este modo, se realizar un cambio proporcional de Ia resistencia de contacto de Ia matriz con Ia nanofibra con el nivel de tensiones a que es sometida, Io cual es indudablemente interesante a Ia hora de hablar de una estructura inteligente. This innovative procedure is based on the change in the electrical resistance of the cementitious material with the addition of carbon nanofibers when subjected to stresses. In this way, a proportional change of the contact resistance of the matrix with the nanofiber is made with the level of stresses to which it is subjected, which is undoubtedly interesting when talking about an intelligent structure.
La función de percepción de Ia deformación mediante adición de nanofibras de carbono consiste en que al someter al material a una compresión, esta resistencia de contacto entre Ia matriz cementicia y Ia nanofibra disminuye, produciendo a su vez el descenso de Ia resistencia eléctrica global en Ia dirección del esfuerzo. Mientras que si Ia tensión aplicada es de tracción el fenómeno generado es el contrario. The function of perception of the deformation by adding carbon nanofibers is that by subjecting the material to compression, this contact resistance between the cement matrix and the nanofiber decreases, producing in turn the decrease of the overall electrical resistance in the effort direction. While the tension applied is tensile, the phenomenon generated is the opposite.
Si Ia tensión aplicada sobrepasa el límite elástico del material se observan efectos irreversibles en Ia respuesta de su resistencia eléctrica. En ese caso, Ia capacidad de percibir Ia deformación del material no es capaz de recuperar totalmente su valor inicial de resistencia ya que en ese nivel tan elevado de tensión ya se han producido dos cambios irreversibles, el fallo del anclaje nanofibra-matriz y Ia rotura de algunas de las nanofibras. El desarrollo de este composite cementicio permite diferentes aplicaciones prácticas: control de vibraciones estructurales, monitorización de tráfico pesado, detección de movimiento en estancias y seguridad de edificios, en tiempo real, entre otros. If the applied tension exceeds the elastic limit of the material, irreversible effects are observed in the response of its electrical resistance. In that case, the ability to perceive the deformation of the material is not able to fully recover its initial resistance value since at that high level of tension there have already been two irreversible changes, the failure of the nanofiber-matrix anchor and the breakage of some of the nanofibers. The development of this cementitious composite allows different practical applications: structural vibration control, heavy traffic monitoring, motion detection in rooms and building security, in real time, among others.
HOJA DE REEMPLAZO (Regla 26)
Descripción de los dibujos REPLACEMENT SHEET (Rule 26) Description of the drawings
En Ia Figura 1 se representa una probeta prismática de dimensiones 4x4x16 cm. Esta probeta utilizada en Ia invención esta fabricada con pasta de cementoFigure 1 shows a prismatic specimen with dimensions 4x4x16 cm. This test tube used in the invention is made of cement paste
Pórtland y nanofibra de carbono del tipo stacked-cup, con un diámetro exterior que varía entre los 20 y 80 nm y un gran hueco central. Dichas nanofibras presentan una relación de aspecto muy alta, con una longitud de varías mieras.Portland and carbon nanofiber of the stacked-cup type, with an outside diameter that varies between 20 and 80 nm and a large central hole. These nanofibers have a very high aspect ratio, with a length of several microns.
El método de medida consiste en introducir Ia corriente por Ia cara superior 1 y Ia cara inferior 2 de Ia probeta y Ia diferencia de potencial se tomó entre los puntos 3 y 4. A partir de los valores de caída de potencial entre los puntos 3 yThe measurement method consists in introducing the current through the upper face 1 and the lower face 2 of the specimen and the potential difference was taken between points 3 and 4. From the potential drop values between points 3 and
4, se calcula Ia variación de las resistividades correspondientes. 4, the variation of the corresponding resistivities is calculated.
En Ia Figura 2 se representa un ejemplo del comportamiento de Ia invención donde se muestra Ia evolución de Ia resistencia eléctrica en función de Ia deformación durante un ensayo de compresión axial. Probeta 4x4x16 cm de pasta de cemento con adición 5% de nanofibra de carbono, amplitud de carga de 4000N y velocidad 100 N/s. En Ia Figura 3 se recoge Ia relación entre el incremento unitario de resistencia eléctrica y Ia deformación unitaria en un ensayo de compresión axial. Probeta 4x4x16 cm de pasta de cemento con adición 5% de nanofibra de carbono, amplitud de carga de 4000N y velocidad 100 N/s. Figure 2 shows an example of the behavior of the invention where the evolution of the electrical resistance as a function of the deformation during an axial compression test is shown. 4x4x16 cm specimen of cement paste with 5% carbon nanofiber addition, 4000N load amplitude and 100 N / s speed. Figure 3 shows the relationship between the unit increase in electrical resistance and the unit deformation in an axial compression test. 4x4x16 cm specimen of cement paste with 5% carbon nanofiber addition, 4000N load amplitude and 100 N / s speed.
Descripción detallada de Ia invención Detailed description of the invention
Esta realización se proporciona a modo de descripción detallada para cubrir completamente el alcance de Ia invención para los expertos en Ia técnica. This embodiment is provided by way of a detailed description to completely cover the scope of the invention for those skilled in the art.
La invención consiste en el uso de nanofibras de carbón en matrices cementicias: pastas, morteros y hormigones, con el objetivo de desarrollar Ia función de percepción de Ia deformación y así poder detectar su propia deformación al verse sometidos a acciones externas sin ningún tipo de sensor The invention consists in the use of carbon nanofibers in cementitious matrices: pastes, mortars and concrete, with the aim of developing the function of perception of the deformation and thus being able to detect its own deformation when subjected to external actions without any sensor
HOJA DE REEMPLAZO (Regla 26)
embebido o adherido. REPLACEMENT SHEET (Rule 26) embedded or attached.
En cuanto a los materiales utilizados y preparación de las probetas, se han considerado probetas prismáticas de dimensiones 4x4x16 cm con pasta de cemento Pórtland y nanofibra de carbono del tipo stacked-cup, con un diámetro exterior que varía entre los 20 y 80 nm y un gran hueco central. Dichas nanofíbras presentan una relación de aspecto muy alta, con una longitud de varias mieras. Los componentes básicos utilizados han sido: As for the materials used and preparation of the specimens, prismatic specimens of dimensions 4x4x16 cm with Portland cement paste and carbon nanofiber of the stacked-cup type have been considered, with an outside diameter that varies between 20 and 80 nm and a large central hole. These nanofibers have a very high aspect ratio, with a length of several microns. The basic components used have been:
• Cemento tipo CEM I 52.5 R. • Cement type CEM I 52.5 R.
• Relación agua cemento a/c=0.5. • Cement water ratio a / c = 0.5.
• Cantidad nanofibra de carbono añadida a Ia mezcla: 5% respecto masa de cemento. • Amount nanofiber of carbon added to the mixture: 5% with respect to cement mass.
• Plastificante (SIKA) en proporción variable. • Plasticizer (SIKA) in variable proportion.
Las probetas se curaron sumergidas en agua durante 28 días antes de ser ensayadas. The specimens were cured submerged in water for 28 days before being tested.
Después se montaron los componentes eléctricos. Se pintaron bandas de pintura de plata 5 alrededor de las probetas para lograr un buen contacto eléctrico entre el monitor de potencial y Ia probeta del composite, entonces se rodearon con hilo de cobre 6 firmemente para tener un punto claro de anclaje entre el monitor de potencial y Ia probeta y que asegure además el contacto eléctrico entre el monitor de potencial y Ia pintura de plata. La cara superior 1 y Ia cara inferior 2 también se cubrieron con pintura de plata. Then the electrical components were mounted. Bands of silver paint 5 were painted around the specimens to achieve a good electrical contact between the potential monitor and the composite specimen, then they were surrounded with copper wire 6 firmly to have a clear anchor point between the potential monitor and the specimen and that also ensures the electrical contact between the potential monitor and the silver paint. The upper face 1 and the lower face 2 were also covered with silver paint.
En cuanto a los instrumentos de ensayo, Ia carga de las probetas se realizó mediante una prensa electromecánica modelo EMI/100/FR, suministrada por Microtest S.A. La resistencia eléctrica se midió gracias a un multímetro digital Keithley 2002 suministrado por National Instruments Inc. La intensidad de corriente fue aplicada mediante una fuente externa Keithley 6021 suministrada por National Instruments Inc. As for the test instruments, the loading of the specimens was carried out by means of an electromechanical press model EMI / 100 / FR, supplied by Microtest S.A. The electrical resistance was measured thanks to a Keithley 2002 digital multimeter supplied by National Instruments Inc. The current was applied using a Keithley 6021 external source supplied by National Instruments Inc.
HOJA DE REEMPLAZO (Regla 26)
Los diferentes ensayos realizados consistieron en monitorizar Ia resistencia eléctrica de Ia probeta en Ia dirección longitudinal mientras se aplicaban ciclos de compresión también longitudinalmente. El valor máximo de carga aplicado en cada ciclo fue de 4 kN, este valor corresponde a menos de un 25% de Ia carga de rotura del material compuesto, situándose en un punto intermedio dentro de Ia zona de deformación elástica del composite, en Ia cual el comportamiento es óptimo y reversible. La velocidad de carga y descarga fue de 100 N/s ya que se evita que una carga más acelerada produzca efectos similares a impactos, Io cual se traduciría en daños irreversibles al composite. Valores menores de velocidad de carga alargan en exceso el ensayo del material. La intensidad de corriente aplicada fue de 0.1mA ya que valores superiores producirían Ia polarización de Ia disolución intersticial del composite (Io cual enmascara Ia medida), evitando asimismo reacciones electroquímicas indeseables sobre los electrodos que también afectan al composite y a Ia monitorización de Ia deformación. Valores menores de corriente reducían significativamente Ia sensibilidad del composite al ensayo realizado. REPLACEMENT SHEET (Rule 26) The different tests carried out consisted of monitoring the electrical resistance of the specimen in the longitudinal direction while applying compression cycles also longitudinally. The maximum load value applied in each cycle was 4 kN, this value corresponds to less than 25% of the breaking load of the composite material, being located at an intermediate point within the elastic deformation zone of the composite, in which The behavior is optimal and reversible. The loading and unloading speed was 100 N / s since a faster accelerated load produces effects similar to impacts, which would result in irreversible damage to the composite. Lower values of loading speed excessively extend the material test. The current intensity applied was 0.1mA since higher values would produce the polarization of the interstitial solution of the composite (which masks the measurement), also avoiding undesirable electrochemical reactions on the electrodes that also affect the composite and the deformation monitoring. Lower current values significantly reduced the sensitivity of the composite to the test performed.
El nivel de percepción de Ia deformación viene caracterizado por el factor de galga (FG). Este parámetro se define como el cambio fraccional de Ia resistividad por unidad de deformación (ε). La siguiente ecuación muestra tal relación: The level of perception of the deformation is characterized by the gauge factor (FG). This parameter is defined as the fractional change of the resistivity per unit of deformation (ε). The following equation shows such a relationship:
FG = _ Δρ/ρ FG = _ Δρ / ρ
ε ε
En donde FG es el factor de galga, Δp es al variación de resistividad [ohm-cm], p es Ia resistividad inicial [ohm-cm], y ε es Ia deformación aplicada (ε = ΔL/L, siendo L Ia longitud de Ia probeta). Where FG is the gauge factor, Δp is the variation of resistivity [ohm-cm], p is the initial resistivity [ohm-cm], and ε is the applied strain (ε = ΔL / L, where L is the length of The test tube).
Según las referencias consultadas, Ia magnitud de las deformaciones es muy pequeña, midiéndose por este motivo Ia resistencia eléctrica en lugar de Ia resistividad. Las medidas de deformación se realizaron utilizando galgas According to the references consulted, the magnitude of the deformations is very small, measuring for this reason the electrical resistance instead of the resistivity. Deformation measurements were performed using gauges
HOJA DE REEMPLAZO (Regla 26)
extensométricas sobre Ia superficie de las probetas. REPLACEMENT SHEET (Rule 26) extensometric on the surface of the specimens.
El método de medida consiste en introducir Ia corriente entre las cara superiorThe measurement method consists in introducing the current between the upper faces
1 y Ia cara inferior 2 de Ia probeta y Ia diferencia de potencial se tomó entre los puntos 3 y 4. A partir de los valores de caída de potencial entre los puntos 3 y1 and the lower face 2 of the specimen and the potential difference was taken between points 3 and 4. From the potential drop values between points 3 and
4, se calcula Ia variación de las resistividades correspondientes. La deformación se calculó como Ia media de los valores registrados por cuatro galgas extensométricas que se situaron en el punto central de cada una de las caras laterales de las probetas, para de esta forma, tener un valor más fiable de Ia deformación real durante el ensayo de carga. 4, the variation of the corresponding resistivities is calculated. The deformation was calculated as the average of the values recorded by four strain gauges that were located at the central point of each of the side faces of the specimens, in order to have a more reliable value of the actual deformation during the test. loading
Las probetas usadas en estos ensayos se almacenaron en un ambiente con humedad relativa del 100% hasta que se estabilizó su peso. La resistividad inicial de las probetas (empleando un método de cuatro puntas) fue aproximadamente de 1575 ohm cm. The specimens used in these tests were stored in an environment with 100% relative humidity until their weight stabilized. The initial resistivity of the specimens (using a four-pointed method) was approximately 1575 ohm cm.
A continuación se muestran los resultados obtenidos después del curado en cámara húmeda. En Ia Figura 2 se muestra Ia evolución de Ia resistencia eléctrica de una probeta de pasta de cemento con un 5% de adición de nanofibra de carbono con Ia deformación que sufre dicha probeta al ser sometida a un esfuerzo de compresión axial. Se usó esta proporción de nanofibra ya que tras estudios iniciales, el comportamiento óptimo del composite desde el punto de vista de Ia monitorización de Ia deformación se obtenía para esta cantidad. Deformaciones negativas se corresponden con compresiones de Ia probeta. Como se puede observar, existe una clara relación entre ambos parámetros, a medida que se comprime Ia probeta se produce una disminución de su resistencia eléctrica, Io cual permite Ia posibilidad de establecer una relación entre ambos parámetros. The results obtained after curing in a wet chamber are shown below. Figure 2 shows the evolution of the electrical resistance of a cement paste specimen with a 5% addition of carbon nanofiber with the deformation that said specimen undergoes when subjected to an axial compression stress. This proportion of nanofiber was used since after initial studies, the optimum behavior of the composite from the point of view of the deformation monitoring was obtained for this amount. Negative deformations correspond to compressions of the specimen. As can be seen, there is a clear relationship between both parameters, as the test piece is compressed there is a decrease in its electrical resistance, which allows the possibility of establishing a relationship between both parameters.
Por otra parte, también se puede apreciar una reversibilidad del comportamiento entre los distintos ciclos de carga a los que es sometida Ia probeta. Cuando cesa el estado de carga, Ia resistencia eléctrica de Ia probeta recupera su valor inicial. Este comportamiento es crítico a Ia hora de poder On the other hand, a reversibility of the behavior between the different loading cycles to which the test piece is subjected can also be appreciated. When the state of charge ceases, the electrical resistance of the specimen recovers its initial value. This behavior is critical when it comes to power.
HOJA DE REEMPLAZO (Regla 26)
tener una buena fiabilidad en Ia función de percepción de Ia deformación. La probeta utilizada es 4x4x16 cm de pasta de cemento con adición 5% de nanofibra de carbono, amplitud de carga de 4000N y velocidad 100 N/s. En Ia Figura 3 se muestra Ia relación entre el incremento unitario de resistencia eléctrica y Ia deformación unitaria en un ensayo de compresión axial. Probeta de pasta de cemento con 5% de adición de nanofibra de carbono. De Ia pendiente de dicha relación se obtiene el parámetro que caracteriza Ia sensibilidad de Ia función de percepción de Ia deformación. REPLACEMENT SHEET (Rule 26) have a good reliability in the function of perception of the deformation. The specimen used is 4x4x16 cm of cement paste with 5% carbon nanofiber addition, 4000N load amplitude and 100 N / s speed. Figure 3 shows the relationship between the unit increase in electrical resistance and the unit deformation in an axial compression test. Cement paste test tube with 5% carbon nanofiber addition. The parameter that characterizes the sensitivity of the deformation perception function is obtained from the slope of said relationship.
HOJA DE REEMPLAZO (Regla 26)
REPLACEMENT SHEET (Rule 26)
Claims
1. Un composite cementicio con adición de nanofibras de carbono que comprende: 1. A cementitious composite with the addition of carbon nanofibers comprising:
a. Una matriz cementicia basa en Ia mezcla de cemento, agua y áridos, presentando esta matriz durante las primeras horas naturaleza plástica, Io que permite darle forma, y que tras un determinado tiempo de varías horas (fraguado) se transforma en un material rígido sensible a las deformaciones. to. A cementitious matrix based on the mixture of cement, water and aggregates, presenting this matrix during the first hours of a plastic nature, which allows it to be shaped, and that after a certain time of several hours (setting) becomes a rigid material sensitive to deformations
b. Un 5% de nanofibra de carbono respecto a Ia masa de cemento que se adiciona a los componentes de Ia matriz cementicia previamente a su amasado. b. 5% of carbon nanofiber with respect to the cement mass that is added to the components of the cement matrix prior to its kneading.
c. Dos contactos eléctricos de pintura de plata aplicada en los extremos de Ia probeta de composite endurecida que permiten Ia aplicación de una corriente eléctrica. C. Two electrical contacts of silver paint applied at the ends of the hardened composite specimen that allow the application of an electric current.
d. Dos contactos eléctricos de pintura de plata e hilo de cobre situados perimetralmente en Ia probeta de composite que permiten Ia monitorización de Ia caída de potencial, y en consecuencia de Ia resistencia eléctrica. d. Two electrical contacts of silver paint and copper wire located perimeter in the composite specimen that allow the monitoring of the potential drop, and consequently of the electrical resistance.
2. Un composite cementicio según Ia reivindicación 1 para monitorizar deformaciones. 2. A cementitious composite according to claim 1 for monitoring deformations.
3. Uso del composite según Ia reivindicación 1 para control de vibraciones estructurales, monitorización de tráfico pesado, detección de movimiento en estancias y seguridad de edificios en tiempo real. 3. Use of the composite according to claim 1 for structural vibration control, heavy traffic monitoring, motion detection in rooms and building security in real time.
HOJA DE REEMPLAZO (Regla 26) REPLACEMENT SHEET (Rule 26)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ESP200901735 | 2009-08-05 | ||
| ES200901735A ES2353544B8 (en) | 2009-08-05 | 2009-08-05 | COMPOSITE CEMENTICIO WITH CARBON NANOFIBRAS FOR MONITORIZATION OF DEFORMATIONS. |
Publications (2)
| Publication Number | Publication Date |
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| WO2011015689A2 true WO2011015689A2 (en) | 2011-02-10 |
| WO2011015689A3 WO2011015689A3 (en) | 2011-03-31 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/ES2010/000341 WO2011015689A2 (en) | 2009-08-05 | 2010-08-02 | Cementitious composite with carbon nanofibers for monitoring deformations |
Country Status (2)
| Country | Link |
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| ES (1) | ES2353544B8 (en) |
| WO (1) | WO2011015689A2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109406582A (en) * | 2018-12-28 | 2019-03-01 | 南水北调东线总公司 | A kind of Structure Damage Identification using carbon fiber change in resistance |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ES2403134B1 (en) * | 2011-11-07 | 2014-03-14 | Universidad De Alicante | COMPOSITE CEMENTICIO WITH CARBON NANOFIBERS FOR HEATING |
| ITUA20162508A1 (en) * | 2016-04-12 | 2017-10-12 | Safecertifiedstructure Ingegneria S R L | Survey method and device for measuring stresses in an agglomerate structure |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0718252A2 (en) * | 1994-12-19 | 1996-06-26 | Mitsubishi Chemical Corporation | Carbon fibre-reinforced concrete and method for preparing the same |
| US5817944A (en) * | 1996-03-19 | 1998-10-06 | The Research Foundation Of State University Of New York | Composite material strain/stress sensor |
| US6079277A (en) * | 1997-12-12 | 2000-06-27 | The Research Foundation Of State University Of New York | Methods and sensors for detecting strain and stress |
-
2009
- 2009-08-05 ES ES200901735A patent/ES2353544B8/en active Active
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- 2010-08-02 WO PCT/ES2010/000341 patent/WO2011015689A2/en active Application Filing
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0718252A2 (en) * | 1994-12-19 | 1996-06-26 | Mitsubishi Chemical Corporation | Carbon fibre-reinforced concrete and method for preparing the same |
| US5817944A (en) * | 1996-03-19 | 1998-10-06 | The Research Foundation Of State University Of New York | Composite material strain/stress sensor |
| US6079277A (en) * | 1997-12-12 | 2000-06-27 | The Research Foundation Of State University Of New York | Methods and sensors for detecting strain and stress |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109406582A (en) * | 2018-12-28 | 2019-03-01 | 南水北调东线总公司 | A kind of Structure Damage Identification using carbon fiber change in resistance |
Also Published As
| Publication number | Publication date |
|---|---|
| ES2353544A1 (en) | 2011-03-03 |
| WO2011015689A3 (en) | 2011-03-31 |
| ES2353544B2 (en) | 2011-09-15 |
| ES2353544B8 (en) | 2019-04-22 |
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