SIST EN 12504-4:2021
(Main)Testing concrete in structures - Part 4: Determination of ultrasonic pulse velocity
Testing concrete in structures - Part 4: Determination of ultrasonic pulse velocity
This document specifies a method for the determination of the velocity of propagation of pulses of ultrasonic longitudinal waves or ultrasonic transverse waves in hardened concrete, which is used for a number of applications.
Prüfung von Beton in Bauwerken - Teil 4: Bestimmung der Ultraschall-Impulsgeschwindigkeit
Dieses Dokument legt ein Verfahren zur Bestimmung der Ausbreitungsgeschwindigkeit von Ultraschall-Longitudinalwellen oder Ultraschall-Transversalwellen aus der Laufzeit von Schallimpulsen in Festbeton für eine Anzahl von Anwendungsfällen fest.
Essais pour béton dans les structures - Partie 4 : Détermination de la vitesse de propagation des ultrasons
Le présent document spécifie une méthode de détermination de la vitesse de propagation des ondes ultrasonores longitudinales ou des ondes ultrasonores transversales dans le béton durci utilisée pour un certain nombre d’applications.
Preskušanje betona v konstrukcijah - 4. del: Določanje hitrosti prehoda ultrazvoka
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN 12504-4:2021
01-september-2021
Nadomešča:
SIST EN 12504-4:2004
Preskušanje betona v konstrukcijah - 4. del: Določanje hitrosti prehoda ultrazvoka
Testing concrete in structures - Part 4: Determination of ultrasonic pulse velocity
Prüfung von Beton in Bauwerken - Teil 4: Bestimmung der Ultraschall-
Impulsgeschwindigkeit
Essais pour béton dans les structures - Partie 4 : Détermination de la vitesse de
propagation des ultrasons
Ta slovenski standard je istoveten z: EN 12504-4:2021
ICS:
91.100.30 Beton in betonski izdelki Concrete and concrete
products
SIST EN 12504-4:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN 12504-4:2021
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SIST EN 12504-4:2021
EN 12504-4
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2021
EUROPÄISCHE NORM
ICS 91.100.30 Supersedes EN 12504-4:2004
English Version
Testing concrete in structures - Part 4: Determination of
ultrasonic pulse velocity
Essais pour béton dans les structures - Partie 4 : Prüfung von Beton in Bauwerken - Teil 4: Bestimmung
Détermination de la vitesse de propagation des der Ultraschall-Impulsgeschwindigkeit
ultrasons
This European Standard was approved by CEN on 30 May 2021.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 12504-4:2021 E
worldwide for CEN national Members.
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SIST EN 12504-4:2021
EN 12504-4:2021 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Apparatus . 5
5.1 General . 5
5.2 Performance requirements . 5
5.3 Transducers . 5
6 Procedures. 6
6.1 Determination of pulse velocity. 6
6.1.1 Factors influencing pulse velocity determination . 6
6.1.2 Transducer arrangement . 6
6.1.3 Path length measurement . 7
6.1.4 Coupling the transducers onto the concrete . 8
6.1.5 Measurement of transit time . 8
7 Expression of result . 8
8 Test report . 9
9 Precision . 9
Annex A (informative) Determination of pulse velocity — indirect transmission . 10
Annex B (informative) Factors influencing pulse velocity determination . 12
Annex C (informative) Correlation of pulse velocity and compressive strength . 15
Bibliography . 17
2
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SIST EN 12504-4:2021
EN 12504-4:2021 (E)
European foreword
This document (EN 12504-4:2021) has been prepared by Technical Committee CEN/TC 104 “Concrete
and related products”, the secretariat of which is held by SN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by January 2022, and conflicting national standards shall
be withdrawn at the latest by January 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 12504-4:2004.
In comparison with the previous edition, the following changes have been made:
— option to use equipment utilizing transverse waves.
This document is one of a series on testing concrete.
EN 12504, Testing concrete in structures, consists of the following parts:
— Part 1: Cored specimens — Taking, examining and testing in compression;
— Part 2: Non-destructive testing — Determination of rebound number;
— Part 3: Determination of pull-out force;
— Part 4: Determination of ultrasonic pulse velocity.
This document is based on the International Standard ISO 1920-7, Testing of concrete — Part 7: Non-
destructive tests on hardened concrete. It is recognized that the ultrasonic pulse velocity determined using
this document is a convention in as much that the path length over which the pulse travels is not always
strictly known.
The measurement of pulse velocity can be used for the determination of the uniformity of concrete, the
presence of cracks or voids, changes in properties with time and in the determination of dynamic physical
properties. These subjects were considered to be outside the scope of this document, but some
information is given in Annex B and more information can be found in the technical literature. The
measurement can also be used to estimate the strength of in situ concrete elements or specimens given
in EN 13791, Assessment of in situ compressive strength in structures and precast concrete components.
However, it is not intended as an alternative to the direct measurement of the compressive strength of
concrete.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United
Kingdom.
3
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SIST EN 12504-4:2021
EN 12504-4:2021 (E)
1 Scope
This document specifies a method for the determination of the velocity of propagation of pulses of
ultrasonic longitudinal waves or ultrasonic transverse waves in hardened concrete, which is used for a
number of applications.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 206, Concrete - Specification, performance, production and conformity
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 206 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https://www.electropedia.org/
— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
transit time
time taken for an ultrasonic pulse to travel from the transmitting transducer to the receiving transducer,
passing through the interposed concrete
Note 1 to entry: Transit time is referred to as time of flight in EN ISO 5577.
3.2
onset
leading edge of the pulse detected by the measuring apparatus
3.3
rise time
time for the leading edge of the first pulse to rise from 10 % to 90 % of its maximum amplitude
4 Principle
A pulse of longitudinal or transverse vibrations is produced by an ultrasonic transducer held in contact
with one surface of the concrete under test. After traversing a known path length in the concrete, the
pulse of vibrations is converted into an electrical signal by a second ultrasonic transducer and an
electronic timing device enables the transit time of the pulse to be measured.
4
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SIST EN 12504-4:2021
EN 12504-4:2021 (E)
5 Apparatus
5.1 General
The ultrasonic test equipment consists of an electrical pulse generator, a pair of transducers, an amplifier
and an electronic timing device for measuring the time interval elapsing between the onset of a pulse
generated at the transmitting transducer and the onset of its arrival at the receiving transducer. A
reference bar or prism is used to zero the instrument or to provide a datum for the velocity measurement.
NOTE 1 This is typically necessary when the user changes the length of the cables being used.
Three forms of the electronic timing devices are available:
a) an oscilloscope on which the first front of the pulse is displayed in relation to a suitable time scale;
b) an interval timer with a direct reading digital display;
c) an A-scan display built directly into the instrument.
NOTE 2 An oscilloscope or integrated A-scan display provides the facility for monitoring the wave form of the
pulse, which can be advantageous in complex testing situations or in automatic system measurements.
5.2 Performance requirements
The ultrasonic test equipment shall conform to the following performance requirements:
— It shall be capable of measuring transit times in the reference bar or prism to a limit deviation
of ± 0,1 µs.
— The electronic excitation pulse applied to the transmitting transducer shall have a rise time of not
greater than one-quarter of its natural period. This is to ensure a sharp pulse onset.
— The pulse repetition frequency shall be low enough to ensure that the onset of the received signal is
free from interference by reverberations.
The ultrasonic test equipment shall be capable of determining the transit time of the first front of the
pulse with the lowest possible threshold, even though this may be of small amplitude compared with that
of the first half wave of the pulse.
The ultrasonic test equipment shall be used within the operating conditions stated by the manufacturer.
5.3 Transducers
The natural frequency of the transducers should normally be within the range 20 kHz to 150 kHz.
NOTE For longitudinal waves, frequencies as low as 10 kHz and as high as 200 kHz can sometimes be used.
High frequency pulses have a well defined onset, but, as they pass through the concrete, they become attenuated
more rapidly than pulses of lower frequency. It is, therefore, preferable to use high frequency transducers (60 kHz
to 200 kHz) for short path lengths (down to 50 mm) and low frequency transducers (10 kHz to 40 kHz) for long
path lengths (up to a maximum of 15 m). Transducers with a frequency of 40 kHz to 60 kHz are found to be useful
for most applications. For ultrasonic pulse-echo measurements using transverse waves the transducer with a
frequency of 40 kHz to 60 kHz is also typical, but in this case the path length is limited to a maximum of
approximately 2,5 m.
5
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SIST EN 12504-4:2021
EN 12504-4:2021 (E)
6 Procedures
6.1 Determination of pulse velocity
6.1.1 Factors influencing pulse velocity determination
In order to provide a determination of pulse velocity, which is reproducible, it is necessary to take into
account various factors which can influence the measurements. These are set out in Annex B.
6.1.2 Transducer arrangement
Although the direction in which the maximum energy is propagated is at right angles to the face of the
transmitting transducer, it is possible to detect pulses which have travelled through the concrete in some
other direction. It is therefore possible to make measurements of pulse velocity by placing the two
transducers on opposite faces (direct transmission), or on adjacent faces (semi-direct transmission), or
the same face (indirect or surface transmission; pulse-echo transmission) (see Figure 1) of a concrete
structure or specimen. In the case of pulse-echo transmission, the receiver detects pulses which have
travelled through the concrete to the opposite surface and have been reflected back to the first surface.
Where it is necessary to place the transducers on opposite surfaces but not directly opposite each other
such arrangement shall be regarded as a semi-direct transmission (see Figure 1 b).
NOTE 1 The indirect transmission arrangement is the least sensitive and is used when only one face of the
concrete is accessible or when the quality of the surface concrete relative to the overall quality is of interest.
NOTE 2 The semi-direct transmission arrangement is used when the direct arrangement cannot be used, for
example at the corners of structures.
NOTE 3 Pulse-echo transmission is an alternative to indirect transmission when only one face of the concrete is
accessible. The sensitivity is comparable with direct transmission.
6
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SIST EN 12504-4:2021
EN 12504-4:2021 (E)
a) Direct transmission b)Semi-direct transmission c) Pulse-echo transmission
Key
R is the receiver transducer
T is the transmitter transducer
Figure 1 — Transducer positioning
6.1.3 Path length measurement
For direct transmission, the path length is the shortest distance between the transducers. The
measurement of the path length shall be recorded to the nearest 1 % of the measured distance.
For semi-direct transmission, it is generally found to be sufficiently accurate to take the path length as
the distance measured from centre to centre of the transducer faces. The accuracy of path length is
dependent upon the size of the transducer compared with the centre to centre distance.
With indirect transmission, the path length is not measured, but a series of measurements is made with
the transducers at different distances apart (see Annex A).
For pulse-echo transmission, the path length is two times the distance from the surface where the
transducer is placed and the opposite surface. The path length shall be recorded as for direct
transmission.
7
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SIST EN 12504-4:2021
EN 12504-4:2021 (E)
6.1.4 Coupling the transducers onto the concrete
There shall be adequate acoustical coupling between the concrete and the face of each transducer. For
many concre
...
SLOVENSKI STANDARD
oSIST prEN 12504-4:2019
01-november-2019
Preskušanje betona - 4. del: Določevanje hitrosti prehoda ultrazvoka
Testing concrete in structures - Part 4: Determination of ultrasonic pulse
Prüfung von Beton in Bauwerken - Teil 4: Bestimmung der Ultraschallgeschwindigkeit
Essais pour béton dans les structures - Partie 4 : Détermination de la vitesse de
propagation des ultrasons
Ta slovenski standard je istoveten z: prEN 12504-4
ICS:
91.100.30 Beton in betonski izdelki Concrete and concrete
products
oSIST prEN 12504-4:2019 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST prEN 12504-4:2019
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oSIST prEN 12504-4:2019
DRAFT
EUROPEAN STANDARD
prEN 12504-4
NORME EUROPÉENNE
EUROPÄISCHE NORM
September 2019
ICS 91.100.30 Will supersede EN 12504-4:2004
English Version
Testing concrete in structures - Part 4: Determination of
ultrasonic pulse
Essais pour béton dans les structures - Partie 4: Prüfung von Beton in Bauwerken - Teil 4: Bestimmung
Determination de la vitesse de propagation du son der Ultraschallgeschwindigkeit
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 104.
If this draft becomes a European Standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations
which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
This draft European Standard was established by CEN in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC
Management Centre has the same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 12504-4:2019 E
worldwide for CEN national Members.
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oSIST prEN 12504-4:2019
prEN 12504-4:2019 (E)
Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 4
4 Principle . 4
5 Apparatus . 5
5.1 General . 5
5.2 Performance requirements . 5
5.3 Transducers . 5
5.4 Apparatus for determination of arrival time of the pulse . 5
6 Procedures. 6
6.1 Determination of Pulse Velocity . 6
6.1.1 Factors influencing pulse velocity measurements . 6
6.1.2 Transducer arrangement . 6
6.1.3 Path length measurement . 7
6.1.4 Coupling the transducer onto the concrete . 8
6.1.5 Measurement of transit time . 8
7 Expression of result . 8
8 Test report . 8
9 Precision . 9
Annex A (informative) Determination of pulse velocity - indirect transmission . 10
Annex B (informative) Factors influencing pulse velocity measurements . 12
B.1 General . 12
B.2 Moisture content . 12
B.3 Temperature of the concrete . 12
B.4 Path length . 12
B.5 Shape and size of specimen . 13
B.6 Effect of reinforcing bars . 13
B.7 Cracks and voids . 13
Annex C (informative) Correlation of pulse velocity and strength . 15
C.1 General . 15
C.2 Correlation using moulded specimens . 15
C.3 Correlation by tests on cores . 15
C.4 Correlation with the strength of precast units . 16
Bibliography . 17
2
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oSIST prEN 12504-4:2019
prEN 12504-4:2019 (E)
European foreword
This document (prEN 12504-4:2019) has been prepared by Technical Committee CEN/TC 104 “Concrete
and related products”, the secretariat of which is held by SN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 12504-4:2004.
This standard is one of a series on testing concrete.
EN 12504, Testing concrete in structures, consists of the following parts:
— Part 1: Cored specimens — Taking, examining and testing in compression;
— Part 2: Non-destructive testing — Determination of rebound number;
— Part 3: Determination of pull-out force;
— Part 4: Determination of ultrasonic pulse velocity.
This document is based on the International Standard ISO 1920-7, Testing of concrete — Part 7: Non-
destructive tests on hardened concrete. It is recognized that the ultrasonic pulse velocity determined using
this document is a convention in as much that the path length over which the pulse travels is not always
strictly known.
The measurement of pulse velocity can be used for the determination of the uniformity of concrete, the
presence of cracks or voids, changes in properties with time and in the determination of dynamic physical
properties. These subjects were considered to be outside the scope of this document, but some
information is given in Annex B and more information can be found in the technical literature. The
measurement can also be used to estimate the strength of in situ concrete elements or specimens given
in EN 13791, Assessment of in situ compressive strength in structures and precast concrete components.
However, it is not intended as an alternative to the direct measurement of the compressive strength of
concrete.
The following amendments have been made to the former edition:
— option to use equipment utilizing transverse waves.
3
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oSIST prEN 12504-4:2019
prEN 12504-4:2019 (E)
1 Scope
This document specifies a method for the determination of the velocity of propagation of pulses of
ultrasonic longitudinal waves or ultrasonic transverse waves in hardened concrete, which is used for a
number of applications.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
EN 206, Concrete — Specification, performance, production and conformity
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 206 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp
3.1
transit time
time taken for an ultrasonic pulse to travel from the transmitting transducer to the receiving transducer,
passing through the interposed concrete
3.2
onset
leading edge of the pulse detected by the measuring apparatus
3.3
rise time
time for the leading edge of the first pulse to rise from 10% to 90% of its maximum amplitude
4 Principle
A pulse of longitudinal or transverse vibrations is produced by an electro-acoustical transducer held in
contact with one surface of the concrete under test. After traversing a known path length in the concrete,
the pulse of vibrations is converted into an electrical signal by a second transducer and electronic timing
circuits enable the transit time of the pulse to be measured.
4
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oSIST prEN 12504-4:2019
prEN 12504-4:2019 (E)
5 Apparatus
5.1 General
The apparatus consists of an electrical pulse generator, a pair of transducers, an amplifier and an
electronic timing device for measuring the time interval elapsing between the onset of a pulse generated
at the transmitting transducer and the onset of its arrival at the receiving transducer. A reference bar or
prism is used to zero the instrument or to provide a datum for the velocity measurement.
NOTE 1 This is typically necessary when the user changes the length of the cables being used.
Three forms of the electronic timing apparatus are available:
a) an oscilloscope on which the first front of the pulse is displayed in relation to a suitable time scale;
b) an interval timer with a direct reading digital display;
c) an A-scan display built directly into the instrument.
NOTE 2 An oscilloscope or integrated A-scan display provides the facility for monitoring the wave form of the
pulse, which can be advantageous in complex testing situations or in automatic system measurements.
5.2 Performance requirements
The apparatus shall conform to the following performance requirements:
— It shall be capable of measuring transit times in the reference bar or prism to a limit deviation
of ± 0,1 µs and an accuracy of 2 %.
— The electronic excitation pulse applied to the transmitting transducer shall have a rise time of not
greater than one-quarter of its natural period. This is to ensure a sharp pulse onset.
— The pulse repetition frequency shall be low enough to ensure that the onset of the received signal is
free from interference by reverberations.
The apparatus shall be used within the operating conditions stated by the manufacturer.
5.3 Transducers
The natural frequency of the transducers should normally be within the range 20 kHz to 150 kHz.
NOTE For longitudinal waves, frequencies as low as 10 kHz and as high as 200 kHz can sometimes be used.
High frequency pulses have a well defined onset, but, as they pass through the concrete, they become attenuated
more rapidly than pulses of lower frequency. It is, therefore, preferable to use high frequency transducers (60 kHz
to 200 kHz) for short path lengths (down to 50 mm) and low frequency transducers (10 kHz to 40 kHz) for long
path lengths (up to a maximum of 15 m). Transducers with a frequency of 40 kHz to 60 kHz are found to be useful
for most applications. For ultrasonic pulse echo measurements using transverse waves the transducer frequency of
40 kHz to 60 kHz is also typical, but the in this case the path length is limited to a maximum of approximately 2,5 m.
5.4 Apparatus for determination of arrival time of the pulse
The apparatus shall be capable of determining the time of arrival of the first front of the pulse with the
lowest possible threshold, even though this may be of small amplitude compared with that of the first
half wave of the pulse.
5
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oSIST prEN 12504-4:2019
prEN 12504-4:2019 (E)
6 Procedures
6.1 Determination of Pulse Velocity
6.1.1 Factors influencing pulse velocity measurements
In order to provide a measurement of pulse velocity, which is reproducible, it is necessary to take into
account various factors which can influence the measurements. These are set out in Annex B.
6.1.2 Transducer arrangement
Although the direction in which the maximum energy is propagated is at right angles to the face of the
transmitting transducer, it is possible to detect pulses which have travelled through the concrete in some
other direction. It is therefore possible to make measurements of pulse velocity by placing the two
transducers on opposite faces (direct transmission), or on adjacent faces (semi-direct transmission), or
the same face (indirect or surface transmission; pulse echo transmission) (see Figure 1) of a concrete
structure or specimen. In the case of pulse echo transmission, the receiver detects pulses which have
travelled through the concrete to the opposite face and have been reflected back to the first face.
Where it is necessary to place the transducers on opposite faces but not directly opposite each other such
arrangement shall be regarded as a semi-direct transmission (see Figure 1.b).
NOTE 1 The indirect transmission arrangement is the least sensitive and is used when only one face of the
concrete is accessible or when the quality of the surface concrete relative to the overall quality is of interest.
NOTE 2 The semi-direct transmission arrangement is used when the direct arrangement cannot be used, for
example at the corners of structures.
NOTE 3 Pulse echo transmission is an alternative to indirect transmission when only one face of the concrete is
accessible. The sensitivity is comparable with direct transmission.
6
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oSIST prEN 12504-4:2019
prEN 12504-4:2019 (E)
Key
R is the receiver transducer
T is the transmitter transducer
Figure 1 — Transducer positioning
6.1.3 Path length measurement
For direct transmission, the path length is the shortest distance between the transducers. The accuracy
of measurement of the path length shall be recorded to an accuracy of ± 1 %.
For semi-direct transmission, it is generally found to be sufficiently accurate to take the path length as
the distance measured from centre to centre of the transducer faces. The accuracy of path length is
dependent upon the size of the transducer compared with the centre to centre distance.
With indirect
...
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