ASTM D6760-02

Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing

SIGNIFICANCE AND USE
This method uses data from ultrasonic probes lowered into parallel access ducts in the pile or structure to assess the homogeneity and integrity of concrete between the probes. The data are used to confirm adequate concrete quality or identify zones of poor quality. If defects are detected, then further investigations should be made by excavation or coring the concrete as appropriate, or by other testing such as Test Method D 1143, D 4945 or D 5882, and measures taken to remediate the structure if a defect is confirmed.
Note 1—The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D 3740 are generally considered capable of competent and objective testing and inspection. Users of this standard are cautioned that compliance with Practice D 3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D 3740 provides a means of evaluating some of those factors.
SCOPE
1.1 This test method covers procedures for checking the homogeneity and integrity of concrete in a deep foundation such as bored piles, drilled shafts, concrete piles or augercast piles. This method can also be extended to diaphragm walls, barrettes, dams etc. The test measures the propagation time and relative energy of an ultrasonic pulse between parallel access ducts installed in the pile or structure. This method is most applicable when performed between tubes that are installed during pile construction.
1.2 Similar techniques with different excitation sources or single access ducts, or both, exist, but these techniques are outside the scope of this test method.
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D 6026.
1.3.1 The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to the accuracy to which data can be applied in design or other uses, or both. How one applies the results obtained using this standard is beyond its scope.
1.4 LimitationsProper installation of the access ducts is essential for effective testing and interpretation. The method does not give the exact type of defect (for example, inclusion, honeycombing, lack of cement particles, etc.) but rather only that a defect exists. The method is limited primarily to testing the concrete between the access ducts and thus gives little information about the concrete outside the reinforcement cage to which the access ducts are attached when the tubes are attached to the inside of the reinforcement cage.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Jan-2002
• ICS: 91.080.40 - Concrete structures
• Technical Committee: D18 - Soil and Rock
• Drafting Committee: D18.11 - Deep Foundations

Relations

• Replaced By: ASTM D6760-08 - Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing
• Effective Date: 01-Jan-2008
• Referred By: ASTM D1143/D1143M-20 - Standard Test Methods for Deep Foundation Elements Under Static Axial Compressive Load
• Effective Date: 10-Jan-2002
• Referred By: ASTM D5882-16 - Standard Test Method for Low Strain Impact Integrity Testing of Deep Foundations
• Effective Date: 10-Jan-2002
• Referred By: ASTM D7383-19 - Standard Test Methods for Axial Rapid Load (Compressive Force Pulse) Testing of Deep Foundations
• Effective Date: 10-Jan-2002
• Referred By: ASTM D8169/D8169M-18 - Standard Test Methods for Deep Foundations Under Bi-Directional Static Axial Compressive Load
• Effective Date: 10-Jan-2002
• Referred By: ASTM D3689/D3689M-22 - Standard Test Methods for Deep Foundation Elements Under Static Axial Tensile Load
• Effective Date: 10-Jan-2002
• Referred By: ASTM D8381/D8381M-21 - Standard Test Methods for Measuring the Depth of Deep Foundations by Parallel Seismic Logging
• Effective Date: 10-Jan-2002
• Referred By: ASTM D3966/D3966M-22 - Standard Test Methods for Deep Foundation Elements Under Static Lateral Load
• Effective Date: 10-Jan-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D 6760 – 02
Standard Test Method for
Integrity Testing of Concrete Deep Foundations by
Ultrasonic Crosshole Testing
This standard is issued under the fixed designation D 6760; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope D 1143 Test Method for Piles Under StaticAxial Compres-
sive Load
1.1 This test method covers procedures for checking the
D 3740 Practice for Minimum Requirements for Agencies
homogeneity and integrity of concrete in a deep foundation
Engaged in the Testing and/or Inspection of Soil and Rock
such as bored piles, drilled shafts, concrete piles or augercast
as Used in Engineering Design and Construction
piles. This method can also be extended to diaphragm walls,
D 4945 Test Method High Strain Dynamic Testing of Piles
barrettes,damsetc.Thetestmeasuresthepropagationtimeand
D 5882 Test Method for Low Strain Integrity Testing of
relative energy of an ultrasonic pulse between parallel access
Piles
ducts installed in the pile or structure. This method is most
D 6026 Practice for Using Significant Digits in Calculating
applicable when performed between tubes that are installed
and Reporting Geotechnical Test Data
during pile construction.
1.2 Similar techniques with different excitation sources or
3. Terminology
single access ducts, or both, exist, but these techniques are
3.1 Definitions of Terms Specific to This Standard:
outside the scope of this test method.
3.1.1 access ducts, n—preformed steel or plastic tubes, or
1.3 All observed and calculated values shall conform to the
drilledboreholes,placedintheconcretetoallowprobeentryin
guidelines for significant digits and rounding established in
pairstomeasurepulsetransmissionintheconcretebetweenthe
Practice D 6026.
probes.
1.3.1 The method used to specify how data are collected,
3.1.2 anomaly, n—irregularity or series of irregularities
calculated, or recorded in this standard is not directly related to
observed in an ultrasonic profile indicating a possible defect.
the accuracy to which data can be applied in design or other
3.1.3 depth interval, n—the maximum incremental spacing
uses, or both. How one applies the results obtained using this
along the pile shaft between ultrasonic pulses.
standard is beyond its scope.
3.1.4 integrity evaluation, n—the qualitative evaluation of
1.4 Limitations—Proper installation of the access ducts is
the concrete continuity and consistency between the access
essential for effective testing and interpretation. The method
ducts or boreholes.
does not give the exact type of defect (for example, inclusion,
3.1.5 specifier, n—the party requesting that the tests are
honeycombing, lack of cement particles, etc.) but rather only
carried out, for example, the engineer or client.
that a defect exists. The method is limited primarily to testing
3.1.6 ultrasonic profile, n—a combined graphical output of
the concrete between the access ducts and thus gives little
a series of measured or processed ultrasonic pulses with depth.
information about the concrete outside the reinforcement cage
3.1.7 ultrasonic pulse, n—data for one specific depth of a
to which the access ducts are attached when the tubes are
shortdurationgeneratedbyatransmitterprobeorsensedbythe
attached to the inside of the reinforcement cage.
receiver probe.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Principle of the Test Method
responsibility of the user of this standard to establish appro-
4.1 The actual velocity of sound wave propagation in
priate safety and health practices and determine the applica-
concrete is dependent on the concrete material properties,
bility of regulatory limitations prior to use.
geometry of the element and wavelength of the sound waves.
When ultrasonic frequencies (for example, >20 000 Hz) are
2. Referenced Documents
generated, Pressure (P) waves and Shear (S) waves travel
2.1 ASTM Standards:
though the concrete. Because S waves are relatively slow, they
are of no further interest in this method. In good quality
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
RockandisthedirectresponsibilityofSubcommitteeD18.11onDeepFoundations.
Current edition approved Jan 10, 2002. Published April 2002. Annual Book of ASTM Standards, Vol 04.08.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6760
criteria of Practice D 3740 are generally considered capable of competent
concrete the P-wave velocity would typically range between
and objective testing and inspection. Users of this standard are cautioned
3600 to 4400 m/s. Poor quality concrete containing anomalies
that compliance with Practice D 3740 does not in itself assure reliable
(for example, soil inclusion, gravel, water, drilling mud,
results.Reliableresultsdependonmanyfactors;PracticeD 3740provides
bentonite, voids, contaminated concrete, or excessive segrega-
a means of evaluating some of those factors.
tion of the constituent particles) has a comparatively lower
P-wave velocity. By measuring the transit time of an ultrasonic
6. Apparatus
P-wavesignalbetweenanultrasonictransmitterandreceiverin
6.1 Apparatus for Allowing Internal Inspection (Access
two parallel water-filled access ducts cast into the concrete
Ducts)—To provide access for the probes, access ducts can be
during construction and spaced at a known distance apart, such
preformed tubes, which are preferably installed during the pile
anomalies may be detected. Usually the transmitter and re-
or structure installation. The tubes shall preferably be mild
ceiver are maintained at equal elevations as they are moved up
steel. Plastic tubes, while not preferred, can be used in special
or down the access ducts. In some cases and for special
circumstances if approved by the test agency but require more
processing the probes may be deliberately offset in relative
frequent attachment to the reinforcing cage to maintain align-
elevation and the use of multiple receivers either in the same
ment. The plastic material must not deform during the high
accessductorinmultipleaccessductscanalsobeallowed.The
temperaturesofconcretecuring.Ifnotubesareinstalledduring
principles and limitations of the test and interpretation of the
construction, boreholes drilled into the pile or structure can be
results are described in the References section.
installed after installation. The internal diameter of the access
4.2 Two ultrasonic probes, one a transmitter and the other a
ducts shall be sufficient to allow the easy passage of the
receiver, are lowered and lifted usually in unison in their
ultrasonic probes over the entire access duct length. If the
respective water-filled access ducts to test the full shaft length
access duct diameter is too large it influences the precision of
from top to bottom. The transmitter probe generates ultrasonic
arrival time and calculated concrete wave speed. Access ducts
pulses at frequent and regular intervals during the probes’
typically have an internal diameter from 38 to 50 mm.
controlled travel rate. The probe depth and receiver probe’s
6.2 Apparatus for Determining Physical Test Parameters:
output (timed relative to the transmitter probe’s ultrasonic
6.2.1 Weighted Measuring Tape—A plumb bob connected
pulse generation) are recorded for each pulse. The receiver’s
to a measuring tape shall be used as a dummy probe to check
output signals are sampled and saved as amplitude versus time
free passage through and determine the unobstructed length of
(see Fig. 1).
each access duct to the nearest 100 mm. The plumb bob shall
4.3 Alternately, the signals may be modulated to a series of
have a diameter similar to the diameter of the probes.
blackandwhitelinescorrespondingrespectivelytothepositive
6.2.2 Magnetic Compass—Amagnetic compass accurate to
and negative peaks of the signal. In either case, the data are
within 10° shall be used to document the access duct designa-
further processed and presented to show the first arrival of the
tions compared with the site layout plan. Alternately, access
ultrasonic pulse and the relative energy of the signal to aid
ducts can be labeled based on the site plan, structure orienta-
interpretation. The processed data are plotted versus depth as a
tion or other methods to document access duct designations
graphical representation of the ultrasonic profile of the tested
assigned and used for reporting test results.
structure. Special test methods to further investigate anomalies
6.3 Apparatus for Obtaining Measurements:
are employed where the probes are not raised together. The
6.3.1 Probes—Probes shall allow a generated or detected
References section lists further sources of information about
pulse within 100 mm of the bottom of the access duct. The
these special test techniques.
weight of each probe shall in all cases be sufficient to allow it
to sink under its own weight in the access ducts. The probe
5. Significance and Use
housing shall be waterproof to at least 1.5 times the maximum
5.1 This method uses data from ultrasonic probes lowered
depth of testing.
into parallel access ducts in the pile or structure to assess the
6.3.2 Transmitter Probe—The transmitter probe shall gen-
homogeneity and integrity of concrete between the probes.The
erate an ultrasonic pulse with a minimum frequency of 30 000
data are used to confirm adequate concrete quality or identify
Hz.
zones of poor quality. If defects are detected, then further
6.3.3 Receiver Probe—The receiver probe shall be of a
investigations should be made by excavation or coring the
similar size and compatible design to the transmitter probe and
concreteasappropriate,orbyothertestingsuchasTestMethod
used to detect the arrival of the ultrasonic pulse generated by
D 1143, D 4945 or D 5882, and measures taken to remediate
the transmitter probe.
the structure if a defect is confirmed.
6.3.4 Probe Centralizer—If the receiver or transmitter
NOTE 1—The quality of the result produced by this standard is
probes, or both, are less than half the access duct diameter,
dependent on the competence of the personnel performing it, and the
each probe shall be fitted with centralizers with effective
suitability of the equipment and facilities used. Agencies that meet the
diameter equivalent to at least 50 % of the access duct
diameter. It shall be designed to minimize any possible
snagging on irregularities in the inner access duct wall.
6.3.5 Signal Transmission Cables—The signal cables used
to deploy the probes and transmit data from the probes shall be
sufficiently robust to support the probes’ weight. The cable
FIG.11msDurationUltrasonic Pulse from Receiver shall be abrasion resistant to allow repeated field use and
D 6760
maintain flexibility in the range of anticipated temperatures. data shall have identifying header information attached to it
All cable connectors or splices, if any, shall be watertight. describingthetestlocation,profileidentifier,datestampandall
Where the signal transmission cables exit the access duct, pertinent information regarding the test.
suitable cable guides, pulleys or cushioning material shall be 6.4.3 Apparatus for Processing Data—The apparatus for
fitted inside the access ducts to minimize abrasion and gener- processing the data shall be a digital computer or micropro-
ally assist with smooth deployment of the probes. cessor capable of analyzing all data to identify at least the first
6.3.6 Probe Depth-Measuring Device—The signal cables arrival and energy of the transmitted ultrasonic pulse at the
shall be passed over or through a pulley with a depth-encoding receiver probe for each depth interval. The data shall then be
device to determine the depth to the location of the transmitter compiled into a single ultrasonic profile for each duct pair.
and receiver on the probes in the access ducts throughout the 6.4.4 Apparatus for Display of Measured Data—The appa-
test. The design of the depth-measuring device shall be such ratus shall be capable of displaying the raw receiver ultrasonic
that cable slippage shall not occur. Preferably a separate pulses to confirm data quality during acquisition. After data
depth-measuring device, such as direct markings on the cables, acquisition, the apparatus shall be capable of displaying the
shall monitor each probe separately so the exact depth of each raw data of each ultrasonic pulse along the entire pile length.
probe is known at all times. (Alternately a single pulley can be The apparatus shall also display the processed ultrasonic
connected to one electronic depth encoder, but then the probes profile. The apparatus may optionally include a printer for on
must remain at the same known relative elevation difference site output of results.
for the entire test.) The depth-measuring device shall be
7. Procedure
accurate to within 1 % of the access duct length, or 0.25 m,
whichever is larger.
7.1 Installation of Preformed Access Ducts:
6.4 Apparatus for Recording, Processing and Displaying 7.1.1 General—The access ducts shall be supplied and
Data:
installed during construction by or in cooperation with the
6.4.1 General—The signals from the transmitter and re- contractorofthepileorstructuretobetested.Thetotalnumber
ceiver probes and the depth-measuring device shall be trans-
of installed access ducts in the pile or structure should be
mitted to a field rugged, dc battery powered, computerized chosen consistent with good coverage of the cross section. As
apparatus for recording, processing and displaying the data in
a guide, the number of access ducts is often selected as one
the form of an ultrasonic profile. A typical schematic arrange- duct for every 0.25 to 0.30 m of pile diameter, with a minimum
mentforthetestapparatusisillustratedinFig.2.Theapparatus ofthreeaccessducts,spacedequallyaroundthecircumference.
shall generate pulses from the transmitter probe either at fixed Typical access duct layout configurations for various structural
depth intervals or at fixed time intervals. In the latter case, the elements are illustrated in Fig. 3.
depth shall be recorded and assigned to each pulse captured by 7.1.2 Preformed Access Tube Preparation—The access
the apparatus for the instant of pulse generation. The rate of tubes shall be straight and free from internal obstructions. The
pulse generation by either method shall generate at least one exterior tube surface shall be free from contamination (for
ultrason
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