DE4239221A1 - Ultrasonic reflectometry for flaw detection in reinforced concrete - compares backscatter measurements over constant distance along and across line of crack during successive phases of test - Google Patents

Ultrasonic reflectometry for flaw detection in reinforced concrete - compares backscatter measurements over constant distance along and across line of crack during successive phases of test

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Publication number
DE4239221A1
DE4239221A1 DE19924239221 DE4239221A DE4239221A1 DE 4239221 A1 DE4239221 A1 DE 4239221A1 DE 19924239221 DE19924239221 DE 19924239221 DE 4239221 A DE4239221 A DE 4239221A DE 4239221 A1 DE4239221 A1 DE 4239221A1
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Prior art keywords
crack
waves
concrete
cracks
excitation
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Withdrawn
Application number
DE19924239221
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German (de)
Inventor
Otto Dr Rer Nat Kroggel
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Priority to DE19924239221 priority Critical patent/DE4239221A1/en
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    • 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
    • G01N33/383—Concrete or cement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/045—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/11—Analysing solids by measuring attenuation of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/24—Probes
    • G01N29/2418—Probes using optoacoustic interaction with the material, e.g. laser radiation, photoacoustics
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/22—Details, e.g. general constructional or apparatus details
    • G01N29/30—Arrangements for calibrating or comparing, e.g. with standard objects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/02—Indexing codes associated with the analysed material
    • G01N2291/023—Solids
    • G01N2291/0232—Glass, ceramics, concrete or stone
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/04—Wave modes and trajectories
    • G01N2291/044—Internal reflections (echoes), e.g. on walls or defects
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/10—Number of transducers
    • G01N2291/102—Number of transducers one emitter, one receiver
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2291/00—Indexing codes associated with group G01N29/00
    • G01N2291/26—Scanned objects
    • G01N2291/263—Surfaces
    • G01N2291/2632—Surfaces flat

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Food Science & Technology (AREA)
  • Medicinal Chemistry (AREA)
  • Ceramic Engineering (AREA)
  • Optics & Photonics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)

Abstract

The ultrasonic receiver (E) is positioned w.r.t. the transmitter (S) so as to receive the sum of all signals backscattered from the underside of a structure with thickness (D) 15 to 100 cm in which a crack (T) threatens to develop into a split. The transmission is evaluated first with the transmitter and receiver placed on the same side, and then with them on opposite sides of the crack at the same spacing. USE/ADVANTAGE - On e.g. sec. barriers of pollutant storage tanks and trays. Cracks detected by visual inspection can be assessed nondestructively for risk of fracture.

Description

Die Erfindung betrifft ein Verfahren zur Beurteilung von Rissen in Stahlbeton dahinge­ hend, ob der Riß die Wandung oder das Bauteil völlig durchdringt (Trennriß) oder ob es sich um einen im Volumen der Betonwandung endenden Riß handelt (Schwindriß o. ä.).The invention relates to a method for assessing cracks in reinforced concrete depending on whether the crack completely penetrates the wall or the component (separation crack) or whether it it is a crack ending in the volume of the concrete wall (shrinkage crack or similar).

Bei einseitig zugänglichen Betonwandungen, wie sie im Fundamentbereich von Hochbau­ ten, bei Stützwänden, bei Auffangwannen oder auch im Behälterbau auftreten, ist es nicht möglich, vom optischen Erscheinungsbild der Rißstruktur auf die Rißtiefe zu schließen.With one-sided accessible concrete walls, such as those in the foundation area of building construction it does not occur in support walls, in collecting trays or in container construction possible to infer the depth of the crack from the visual appearance of the crack structure.

Für Bauwerke, bei denen der Beton eine Dichtfunktion zu erfüllen hat, ist es jedoch ent­ scheidend, daß keine Trennrisse vorliegen. Insbesondere gilt dies bei Bauwerken, in denen Betonwannen oder Behälter zum Schutz vor umweltgefährdenden Stoffen eingesetzt wer­ den, z. B. bei sog. Tanktassen.For buildings where the concrete has a sealing function, however, it is ent deciding that there are no separation cracks. This applies in particular to structures in which Concrete trays or containers to protect against environmentally hazardous substances the, e.g. B. in so-called tank cups.

Es ist Stand der Technik, aufgefundene Risse bei nur einseitiger Zugänglichkeit mit zerstö­ renden Methoden zu untersuchen.It is state of the art to destroy found cracks with only one-sided accessibility investigate other methods.

Es werden Kernbohrungen vorgenommen, die es erlauben, die Rißtiefe am Bohrkernort zu ermitteln. Voraussetzung für eine sichere Beurteilung ist, daß der Riß mit Injektionsharz oder vergleichbarem Material verpreßt und damit stabilisiert wird und daß der Rißverlauf im Bohrkern zu verfolgen ist, also keine zu große Abweichung von der Bohrrichtung auf­ tritt.Core drilling is carried out, which makes it possible to increase the depth of the crack at the core location determine. A prerequisite for a reliable assessment is that the crack with injection resin or comparable material is pressed and thus stabilized and that the course of the crack is to be traced in the drill core, i.e. not too great a deviation from the drilling direction occurs.

Eine punktuelle Beurteilung der Rißtiefe in einem im allgemeinen ausgedehnten Rißbe­ reich ist damit möglich. Das entstandene Bohrloch muß mit geeignetem Material verfüllt werden.A punctual assessment of the depth of crack in a generally large crack rich is possible with it. The resulting borehole must be filled with suitable material become.

Eine flächendeckende Untersuchung mit dem Ziel der Trennrißerkennung ist damit prak­ tisch nicht möglich, da die Dichtwirkung der Struktur durch die Vielzahl der Bohrlöcher selbst in Frage gestellt wird.A comprehensive investigation with the aim of detecting the separation crack is therefore practical not possible due to the large number of drill holes is questioned itself.

Aufgabe der Erfindung ist es, ein Verfahren anzugeben, das es erlaubt, durch visuelle Inspektion festgestellte Risse dahingehend zerstörungsfrei zu beurteilen, ob es sich um Trennrisse handelt.The object of the invention is to provide a method that allows visual Inspection found cracks to assess non-destructively whether it is Separating cracks.

Ultraschallwellen in Beton werden an den Zuschlagsstoffen, der Bewehrung und an der Rückwand des Bauteils reflektiert. Bei einer Anordnung von Sender (S) und Empfänger (E) gemäß Bild 1 wird der Empfänger (E) die Summe aller rückgestreuten Signale empfan­ gen.Ultrasonic waves in concrete are reflected on the aggregates, the reinforcement and on the rear wall of the component. If the transmitter (S) and receiver (E) are arranged as shown in Figure 1, the receiver (E) will receive the sum of all backscattered signals.

Tritt eine Materialtrennung (Trennriß nach Bild 1 entlang der Linie T) auf, ändert sich das Übertragungsverhalten zwischen Sender und Empfänger gegenüber dem ungestörten Stahl­ betonvolumen.If a material separation occurs (separation tear according to Figure 1 along the line T), the transmission behavior between transmitter and receiver changes compared to the undisturbed steel concrete volume.

Insbesondere wird die Amplitude des Empfangssignals stark reduziert, und es bilden sich praktisch keine stehenden Ultraschallwellen im betrachteten Frequenzbereich (50-300 kHz) mehr aus. Diese Änderung geht für die praktisch relevanten Bauteildicken D (siehe Bild 1) von 0,15-1,0 m eindeutig mit der Ausbildung eines Trennrisses einher.In particular, the amplitude of the received signal is greatly reduced, and practically no standing ultrasonic waves form in the frequency range under consideration (50-300 kHz). For the practically relevant component thicknesses D (see Figure 1) of 0.15-1.0 m, this change clearly goes hand in hand with the formation of a separation crack.

Risse, die im Volumen des Bauteils bzw. der Wandung enden, zeigen eine derartige Ände­ rung nicht.Cracks that end in the volume of the component or the wall show such a change not.

Die Untersuchung eines visuell erkennbaren Risses ist damit in zwei Arbeitsschritten ohne weitere Kenntnis der Betoneigenschaften und der genauen Bauteil- bzw. Wanddicke mög­ lich (Position A und Position B der Prüfköpfe in Bild 3).The investigation of a visually recognizable crack is therefore possible in two steps without further knowledge of the concrete properties and the exact component or wall thickness (position A and position B of the test heads in Figure 3).

  • 1) Bestimmung des Übertragungsverhaltens Sender/Empfänger auf einer Seite des visu­ ell erkennbaren Risses (Position A, Bild 3).1) Determine the transmission behavior of the transmitter / receiver on one side of the visually recognizable crack (position A, Figure 3).
  • 2) Bestimmung des Übertragungsverhaltens Sender/Empfänger mit der Positionierung auf beiden Seiten des Risses (Position B, Bild 3, bzw. Bild 1).2) Determine the transmission behavior of the transmitter / receiver with the positioning on both sides of the crack (position B, Figure 3 or Figure 1).

Sender/Empfänger-Abstand wird konstant gehalten. The transmitter / receiver distance is kept constant.  

Die Änderung des Übertragungsverhaltens Sender/Empfänger in Frequenzdarstellung beim Übergang vom Anriß (2/3 Bauteildicke) zum Trennriß wird in Bild 2 gezeigt. Die Ände­ rung des Übertragungsverhaltens tritt auf, auch wenn der Trennriß bereichsweise über­ drückt ist.The change in the transmission behavior of the transmitter / receiver in frequency representation during the transition from the crack (2/3 component thickness) to the tear is shown in Figure 2. The change in the transmission behavior occurs even if the separation tear is partially suppressed.

Erklärung zu Bild 1Explanation of picture 1

Sender (S) und Empfänger (E) sind so positioniert, daß der Trennriß zwischen beiden verläuft. Das entspricht der Position B in Bild 3Transmitter (S) and receiver (E) are positioned so that the separation tear runs between them. This corresponds to position B in Figure 3

Erklärung zu Bild 2Explanation of picture 2

Die Amplituden der rückgestreuten Signale ändern sich beim Auftreten eines Trennrisses in charakteristischer Weise, wie schematisch in Bild 2 dargestellt. A und B entsprechen den Positionen des Bildes 3.The amplitudes of the backscattered signals change in a characteristic manner when a separation crack occurs, as shown schematically in Figure 2. A and B correspond to the positions of image 3.

Erklärung zu Bild 3Explanation of picture 3

Es wird die Position von Sender und Empfänger in den beiden Untersuchungsschritten gezeigt. Dies entspricht der Seitenansicht des Bildes 1. Die Entfernung A zwischen Sender und Empfänger ist in Position A und Position B gleich. Für die Position A wird ein ungestörter Betonbereich gewählt.The position of sender and receiver in the two examination steps is shown. This corresponds to the side view of image 1. The distance A between transmitter and receiver is the same in position A and position B. An undisturbed concrete area is selected for position A.

Claims (6)

1. Die Erfindung betrifft ein Reflexionsverfahren zur Beurteilung von Rissen in unbe­ wehrtem, bewehrtem und vorgespanntem Beton dahingehend, ob ein Trennriß oder ein Oberflächenriß, der keine vollständige Materialtrennung bewirkt, vorliegt. Bei dem Verfahren werden auf der Betonoberfläche an einem Rißufer mechanische Wellen, insbesondere Hörschallwellen und Ultraschallwellen angeregt, auf dem anderen Rißufer auf der Betonoberfläche gegenüber der Anregungsstelle werden mit einem geeigneten Empfänger die reflektierten Schallwellen beobachtet und regi­ striert. Durch Vergleich von angeregter Schallwelle und reflektierter Schallwelle im Zeit- und Frequenzbereich wird auf das Vorliegen eines Trenn- oder eines Oberflä­ chenrisses geschlossen.1. The invention relates to a reflection method for assessing cracks in unbe reinforced, reinforced and prestressed concrete whether a separation crack or there is a surface crack that does not completely separate the material. In the process, mechanical cracks are formed on the surface of the concrete Waves, especially hearing sound waves and ultrasonic waves, are excited on the other cracks on the concrete surface opposite the excitation point are also the reflected sound waves are observed and regi strictly. By comparing the excited sound wave and the reflected sound wave in the Time and frequency range is based on the presence of a separation or a surface Chenrisses closed. 2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß zur Anregung und zum Empfang Ultraschallprüfköpfe im Frequenzbereich 50-300 kHz benutzt werden.2. The method according to claim 1, characterized in that for excitation and Reception ultrasonic probes in the frequency range 50-300 kHz can be used. 3. Verfahren nach Anspruch 1 und 2, dadurch gekennzeichnet, daß zur Anregung defi­ nierte Stoßbelastungen (Hammerschläge) benutzt werden und die reflektierten elasti­ schen Wellen mit geeigneten Sensoren wie Körperschallprüfköpfen oder Beschleuni­ gungsaufnehmern gemessen werden.3. The method according to claim 1 and 2, characterized in that defi for excitation nated shock loads (hammer blows) are used and the reflected elastic waves with suitable sensors such as structure-borne noise probes or accelerators sensor can be measured. 4. Verfahren nach 1, 2 und 3, dadurch gekennzeichnet, daß die Schwingungsamplitude der Betonoberfläche im Rißbereich mit optischen Verfahren (Laservibrometer) flä­ chendeckend und bildgebend gemessen wird.4. The method according to 1, 2 and 3, characterized in that the vibration amplitude of the concrete surface in the crack area using optical methods (laser vibrometer) covering and imaging is measured. 5. Verfahren nach 1-4, dadurch gekennzeichnet, daß die Kalibrierung der Übertragungsstrecke Anregung-Rißbereich-Empfänger in Rißnähe am ungestörten Beton vorgenommen wird und die Differenzen zwischen der Messung im gestörten Rißbe­ reich und dem ungestörten Bereich der Interpretation der Meßergebnisse zugrunde­ gelegt wird.5. The method according to 1-4, characterized in that the calibration of the transmission link Excitation crack area receiver near the crack on the undisturbed concrete is made and the differences between the measurement in the disturbed Rißbe rich and the undisturbed area of interpretation of the measurement results is placed. 6. Verfahren nach 1-5, dadurch gekennzeichnet, daß bei der Beurteilung von Rissen die Frequenzabhängigkeit der Übertragung der Wellen genutzt wird und einzelne mit der Schallaufzeit eindeutig korrelierte Resonanzen (stehende Wellen) beobachtet werden.6. The method according to 1-5, characterized in that the assessment of cracks Frequency dependence of the transmission of the waves is used and individual with the Sound propagation time clearly correlated resonances (standing waves) observed become.
DE19924239221 1992-11-21 1992-11-21 Ultrasonic reflectometry for flaw detection in reinforced concrete - compares backscatter measurements over constant distance along and across line of crack during successive phases of test Withdrawn DE4239221A1 (en)

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DE19924239221 DE4239221A1 (en) 1992-11-21 1992-11-21 Ultrasonic reflectometry for flaw detection in reinforced concrete - compares backscatter measurements over constant distance along and across line of crack during successive phases of test

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998008111A1 (en) * 1996-08-22 1998-02-26 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Method for three-dimensional and non-destructive detection of structures
WO2001079831A2 (en) * 2000-04-13 2001-10-25 The Johns Hopkins University Nondestructive detection of reinforcing member degradation
EP1480040A2 (en) * 2003-05-23 2004-11-24 Asociacion de Investigacion de las Industrias de la Construccion (AIDICO) Procedure to diagnose the quality in blocks of ornamental rock of large dimensions and devices for its implementation
EP1544610A1 (en) * 2003-12-19 2005-06-22 Siemens Aktiengesellschaft Method and apparatus for detecting cracks in ceramic heat shield elements
US11536698B2 (en) 2021-04-20 2022-12-27 Imam Abdulrahman Bin Faisal University Development of non-destructive testing method to evaluate bond condition of reinforced concrete beam

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998008111A1 (en) * 1996-08-22 1998-02-26 Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. Method for three-dimensional and non-destructive detection of structures
WO2001079831A2 (en) * 2000-04-13 2001-10-25 The Johns Hopkins University Nondestructive detection of reinforcing member degradation
WO2001079831A3 (en) * 2000-04-13 2002-08-15 Univ Johns Hopkins Nondestructive detection of reinforcing member degradation
EP1480040A2 (en) * 2003-05-23 2004-11-24 Asociacion de Investigacion de las Industrias de la Construccion (AIDICO) Procedure to diagnose the quality in blocks of ornamental rock of large dimensions and devices for its implementation
EP1480040A3 (en) * 2003-05-23 2004-12-01 Asociacion de Investigacion de las Industrias de la Construccion (AIDICO) Procedure to diagnose the quality in blocks of ornamental rock of large dimensions and devices for its implementation
ES2263307A1 (en) * 2003-05-23 2006-12-01 Asociacion De Investigacion De Industrias De La Construccion Aidico Procedure to diagnose the quality in blocks of ornamental rock of large dimensions and devices for its implementation
EP1544610A1 (en) * 2003-12-19 2005-06-22 Siemens Aktiengesellschaft Method and apparatus for detecting cracks in ceramic heat shield elements
US11536698B2 (en) 2021-04-20 2022-12-27 Imam Abdulrahman Bin Faisal University Development of non-destructive testing method to evaluate bond condition of reinforced concrete beam
US11686708B2 (en) 2021-04-20 2023-06-27 Imam Abdulrahman Bin Faisal University Non-destructive testing method for testing a steel reinforced concrete beam
US11796512B2 (en) 2021-04-20 2023-10-24 Imam Abdulrahman Bin Faisal University Ultrasonic pulse method for testing steel rod reinforced concrete beams

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