ASTM C1383-98a

Standard Test Method for Measuring the P-Wave Speed and the Thickness of Concrete Plates Using the Impact-Echo Method

SCOPE
1.1 This test method covers procedures for determining the thickness of concrete slabs, pavements, bridge decks, walls, or other plate-like structure using the impact-echo method.

General Information

• Status: Historical
• Publication Date: 09-Nov-1998
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.64 - Nondestructive and In-Place Testing

Relations

• Replaced By: ASTM C1383-04 - Standard Test Method for Measuring the P-Wave Speed and the Thickness of Concrete Plates Using the Impact-Echo Method
• Effective Date: 01-Jun-2004
• Referred By: ASTM C1740-16 - Standard Practice for Evaluating the Condition of Concrete Plates Using the Impulse-Response Method
• Effective Date: 10-Nov-1998

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: C 1383 – 98a
Standard Test Method for
Measuring the P-Wave Speed and the Thickness of
Concrete Plates Using the Impact-Echo Method
This standard is issued under the fixed designation C 1383; 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 3. Terminology
1.1 This test method covers procedures for determining the 3.1 Definitions:
thickness of concrete slabs, pavements, bridge decks, walls, or 3.1.1 acoustic impedance—the product of P-wave speed
other plate-like structure using the impact-echo method. and density that is used in computations of characteristics of
1.2 The following two procedures are covered in this test stress wave reflection at boundaries.
method: 3.1.2 amplitude spectrum—a plot of relative amplitude
1.2.1 Procedure A: P-Wave Speed Measurement—This pro- versus frequency that is obtained from the waveform using a
cedure measures the time it takes for the P-wave generated by Fourier transform technique.
a short-duration, point impact to travel between two transduc- 3.1.3 Fourier transform—a numerical technique used to
ers positioned a known distance apart along the surface of a convert digital waveforms from the time domain to the
structure. The P-wave speed is calculated by dividing the frequency domain.
distance between the two transducers by the travel time. 3.1.3.1 Discussion—The peaks in the amplitude spectrum
1.2.2 Procedure B: Impact-Echo Test—This procedure mea- correspond to the dominant frequencies in the waveform.
sures the frequency with which the P-wave generated by a 3.1.4 impact-echo method—a send-receive nondestructive
short-duration, point impact is reflected between the parallel test method based on the use of a short-duration mechanical
(opposite) surfaces of a plate. The thickness is calculated from impact to generate transient stress waves and the use of a
this measured frequency and the P-wave speed obtained from broadband receiving transducer placed adjacent to the impact
Procedure A. point.
1.2.3 Both Procedure A and Procedure B must be performed 3.1.4.1 Discussion—Waveforms are converted to the fre-
at each point where a thickness determination is made. quency domain and the resulting amplitude spectra are ana-
1.3 The values stated in SI units are to be regarded as the lyzed to obtain the dominant frequencies in the structure’s
standard. response to the impact. These frequencies are used to deter-
1.4 This standard does not purport to address all of the mine the thickness of the structure or the presence of flaws.
safety concerns, if any, associated with its use. It is the 3.1.5 impact duration—the time that the impactor used to
responsibility of the user of this standard to establish appro- generate stress waves is in contact with the test surface. Also
priate safety and health practices and determine the applica- referred to as contact time.
bility of regulatory limitations prior to use. 3.1.5.1 Discussion—The impact duration is a critical aspect
1.5 The text of this standard references notes and footnotes in the success of the two procedures covered by this method.
which provide explanatory material. These notes and footnotes Recommended impact durations are given. In practice, the
(excluding those in tables and figures) shall not be considered impact duration will depend on the type of impactor and the
as requirements of the standard. condition of the concrete at the point of impact. Smooth, hard
surfaces will result in shorter impact durations than rough, soft
2. Referenced Documents
surfaces. The user should verify that the impact durations are
2.1 ASTM Standards:
within the recommended ranges. An approximate measure of
C 597 Test Method for Pulse Velocity Through Concrete the impact duration can be obtained from the portion of the
E 1316 Terminology for Nondestructive Examinations
waveform corresponding to the surface wave arrival. Fig. 1
shows an example of the surface-wave portion of a waveform
and the approximate contact time is indicated.
This test method is under the jurisdiction of ASTM Committee C-9 on Concrete
3.1.6 P-wave—the dilatational (longitudinal or primary)
and Concrete Aggregates and is the direct responsibility of Subcommittee C09.64
stress wave which causes particle displacement parallel to the
on Nondestructive and In-Place Testing.
Current edition approved Nov. 10, 1998. Published April 1999. Originally
published as C 1383–98. Last previous edition C 1383–98.
2 4
Annual Book of ASTM Standards, Vol 04.02. Sansalone, M. and Streett, W.B., Impact-Echo: Nondestructive Evaluation of
Annual Book of ASTM Standards, Vol 03.03. Concrete and Masonry, Bullbrier Press, Ithaca, NY and Jersey Shore, PA, 1997.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1383 – 98a
apparent P-wave speed that is related to the plate thickness
through the following equation:
C
p, plate
T 5 (2)
2f
where:
T = the thickness of the plate, and
f = the frequency of the P-wave thickness mode of the
plate obtained from the amplitude spectrum.
3.2.2 plate—any prismatic structure where the lateral di-
mensions are at least six times the thickness.
3.2.2.1 Discussion—Minimum lateral dimensions are nec-
essary to prevent plate modes of vibration from interfering
with the identification of the thickness mode frequency in the
amplitude spectrum. The minimum lateral dimensions and
acceptable sampling period are related, as explained in Note 9.
FIG. 1 Expanded View of Surface-Wave Portion of Waveform
4. Significance and Use
Showing the Width of the Surface Wave Signal as an
4.1 This test method may be used as a substitute for, or in
Approximation of the Contact Time of the Impact
conjunction with, coring to determine the thickness of slabs,
pavements, decks, walls, or other plate structures. There is a
direction of wave propagation. This wave produces normal
certain level of systematic error in the calculated thickness due
stresses (tensile or compressive) as it propagates.
to the discrete nature of the digital records that are used. The
3.1.7 P-wave speed—the speed with which the P-wave
absolute systematic error depends on the plate thickness, the
propagates through a semi-infinite solid.
sampling interval, and the sampling period.
3.1.7.1 Discussion—The P-wave speed is the same as the
4.2 Because the wave speed can vary from point-to-point in
compressional pulse velocity measured according to Test
the structure due to differences in concrete age or batch-to-
Method C 597.
batch variability, the wave speed is measured (Procedure A) at
3.1.8 sampling period—the duration of the waveform which
each point where a thickness determination (Procedure B) is
equals the number of points in the waveform multiplied by the
required.
sampling interval.
4.3 The maximum and minimum thickness that can be
3.1.9 sampling interval—the time difference between any
measured is limited by the details of the testing apparatus
two adjacent points in the waveform.
(transducer response characteristics and the specific impactor).
3.1.10 surface wave—a stress wave in which the particle
The limits shall be specified by manufacturer of the apparatus,
motion is elliptical and the amplitude of particle motion
and the apparatus shall not be used beyond these limits. If test
decreases rapidly with depth. Also known as Rayleigh wave (or
equipment is assembled by the user, thickness limitations shall
R-wave).
be established and documented.
3.1.11 waveform—a recorded signal from a transducer that
4.4 This test method is not applicable to plate structures
is a plot of voltage versus time.
with overlays, such as a concrete bridge deck with an asphalt
3.1.12 Refer to Terminology E 1316 for additional defini-
or portland cement concrete overlay. The method is based on
tions, related to nondestructive ultrasonic examination, that are
the assumption that the concrete plate has the same P-wave
applicable to this test method.
speed throughout its depth.
3.2 Definitions of Terms Specific to This Standard:
,
4 5
4.5 Procedure A is performed on concrete that is dry as a
3.2.1 apparent P-wave speed in a plate —a parameter that
high surface moisture content may affect the results.
is 0.96 of the P-wave speed:
4.6 Procedure B is applicable to a concrete plate resting on
C 5 0.96 C (1)
p, plate p
a subgrade of soil, gravel, permeable asphalt concrete, or lean
where:
portland cement concrete provided there is sufficient difference
C = the apparent P-wave speed in a plate, and
in acoustic impedance between the concrete and subgrade or
p, plate
C = the P-wave speed in concrete that is obtained
p there are enough air voids at the interface to produce measur-
from Procedure A.
able reflections. If these conditions are not satisfied, the
3.2.1.1 Discussion—This parameter is used in thickness
waveform will be of low amplitude and the spectrum will not
calculations in impact-echo measurements on plates. The
include a dominant peak at the frequency corresponding to the
P-wave speed in a material (concrete) is converted to the
thickness (Eq 2). If the interface between the concrete and
subgrade is rough, the amplitude spectrum will have a rounded
peak instead of a sharp peak associated with a flat surface.
Sansalone, M., Lin, J. M., and Streett, W. B., “A Procedure for Determining
4.7 The procedures described are not influenced by traffic
P-wave Speed in Concrete for Use in Impact-Echo Testing Using P-wave Speed
noise or low frequency structural vibrations set up by normal
Measurement Technique,” ACI Journal, Vol. 94, No. 6, November-December 1997,
pp. 531–539. movement of traffic across a structure.
C 1383 – 98a
4.8 The procedures are not applicable in the presence of tips shall be placed about 300 mm apart. Measure and record to
mechanical noise created by equipment impacting (jack ham- the nearest 1 mm the actual distance between the centers of the
mers, sounding with a hammer, mechanical sweepers, and the transducer tips.
like) on the structure.
NOTE 3—The accuracy of the measurement is affected if the distance
4.9 Procedure A is not applicable in the presence of high
between the tips of the two transducers is not known accurately. The
amplitude electrical noise, such as may produced by a genera-
materials and design of the spacer device should be chosen to minimize
tor or some other source, that is transmitted to the data-
the change in separation of the transducers due to changes in temperature.
acquisition system.
6.4 Data-Acquisition System—Hardware and software for
acquiring, recording, and processing the output of the two
PROCEDURE A—P-WAVE SPEED MEASUREMENT
transducers. This system can be a portable computer with a
5. Summary of Procedure
two-channel data-acquisition card, or it can be a portable
two-channel waveform analyzer.
5.1 An impact on the concrete surface is used to generate
6.4.1 The sampling rate for each channel shall be 500 kHz
transient stress waves. These waves propagate along the
surface of the concrete past two transducers, placed on a line or higher (sampling interval of 2 μs or less). The system shall
be capable of triggering on the signal from one of the recording
through the impact point and at a known distance apart.
5.2 The time difference between the arrival of the P-wave channels.
(stress wave with highest speed) at each transducer is used to 6.4.2 The voltage range and voltage resolution of the data
determine the P-wave speed by dividing the time difference aquisition system shall be matched with the sensitivity of the
(travel time) by the known distance between the transducers. transducers so that the arrival of the P-wave is determined
accurately.
6. Apparatus
NOTE 4—For example, a computer data acquisition card with a voltage
6.1 Impactor—The impactor shall be spherical or spheri-
range of 6 2.5 V and 12-bit resolution has been found to be suitable for
cally tipped. It shall produce an impact duration of 30 6 10 μs
the transducer described in Note 2.
with sufficient energy to produce surface displacements due to
6.4.3 The display system shall include cursors, including a
the P-wave that can be recorded by the two transducers (see
corresponding readout of time and voltage, that can be posi-
Note 1). The impactor shall be positioned to strike on the
tioned at the point in each waveform corresponding to the
centerline passing through the two transducers at a distance of
P-wave arrival.
150 6 10 mm from the first transducer.
6.4.4 The data-acquisition system shall be operated by a
NOTE 1—Hardened steel balls ranging from 5 to 8 mm in diameter and
power source that does not produce electrical noise detectable
attached to steel spring rods have been found to produce suitable impacts.
by the transducers and data acquisition system when the system
6.2 Transducers— Two broadband, piezoelectric transduc-
is set at the voltage sensitivity required to detect the arrivals of
ers that respond to normal surface displacements. These
the P-wave.
transducers must be capable of detecting the small displace-
NOTE 5—Battery-powered data acquisition systems have been found
ments that correspond to the arrival of the impact-generated
suitable.
P-wave traveling along the surface. A small contact area
6.5 Cables and Connectors—To connect the transducers to
between the piezoelectric element and the concrete surface is
required to record accurately the arrival of the P-wave (see the data acquisition system. Connectors shall be high quality
and tightly connected to the cables. The cables shall be
Note 2). Use a suitable material to couple the transducer to the
concrete. shielded to reduce electrical noise.
6.6 Functionality Check Apparatus—Apparatus to verify
NOTE 2—A commercially available displacement transducer made from
that all components of test system are functioning properly
a conical piezoelectric element with a tip diameter of 1.5 mm and the
prior to the start of testing. This may include a reference test
larger end attached to a brass backing block has been found suitable. A
specimen whose impact response has been determined and can
lead sheet approximately 0.25 mm thick is a suitable coupling material for
such a transducer.
be compared with the output of the test system.
6.2.1 Acceptable transducers shall be previously docu-
7. Preparation of Test Surface
mented to produce accurate results for plate thicknesses similar
to those being measured by this test method.
7.1 The test surface shall be dry. Remove dir
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