ASTM D6087-97(2001)

Standard Test Method for Evaluating Asphalt-Covered Concrete Bridge Decks Using Ground Penetrating Radar

SCOPE
1.1 This test method covers several radar evaluation procedures that can be used to evaluate the condition of concrete bridge decks overlaid with asphaltic concrete wearing surfaces. Specifically, this test method predicts the presence or absence of delamination.
1.2 The most serious form of deterioration is that which is caused by corrosion of embedded reinforcement. Corrosion is initiated by deicing salts, used for snow and ice control in the winter months, penetrating the concrete. In arid climates, the corrosion can be initiated by chloride ions contained in the mix ingredients.
1.2.1 As the reinforcing steel corrodes, it expands and creates a crack or subsurface fracture plane in the concrete at or just above the level of the reinforcement. The fracture plane, or delamination, may be localized or may extend over a substantial area, especially if the concrete cover to the reinforcement is small. It is not uncommon for more than one delamination to occur on different planes between the concrete surface and the reinforcing steel. Delaminations are not visible on the concrete surface. However, if repairs are not made, the delaminations progress to open spalls and, with continued corrosion, eventually affect the structural integrity of the deck.
1.3 This test method may not be suitable for evaluating bridges with delamination which are localized over the diameter of the reinforcement, or for those bridges which have cathodic protection (coke breeze as cathode) installed on the bridge or for which a conductive aggregate has been used in the asphalt (that is, blast furnace slag). This is because metals are perfect reflectors of EM waves, since the wave impedances for metals are zero.
1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units given in parentheses are for information only. Specific precautionary statements are given in Section 5.
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-Mar-1997
• ICS: 91.080.40 - Concrete structures
• Technical Committee: D04 - Road and Paving Materials
• Drafting Committee: D04.32 - Bridges and Structures

Relations

• Replaces: ASTM D6087-97e1 - Standard Test Method for Evaluating Asphalt-Covered Concrete Bridge Decks Using Ground Penetrating Radar
• Effective Date: 10-Mar-1997
• Replaced By: ASTM D6087-03 - Standard Test Method for Evaluating Asphalt-Covered Concrete Bridge Decks Using Ground Penetrating Radar
• Effective Date: 10-Feb-2003

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 6087 – 97 (Reapproved 2001)
Standard Test Method for
Evaluating Asphalt-Covered Concrete Bridge Decks Using
Ground Penetrating Radar
This standard is issued under the fixed designation D 6087; 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 priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
1.1 This test method covers several radar evaluation proce-
dures that can be used to evaluate the condition of concrete
2. Summary of Test Method
bridge decks overlaid with asphaltic concrete wearing surfaces.
2.1 A vehicle equipped with a short-pulse ground penetrat-
Specifically, this test method predicts the presence or absence
ing radar, data acquisition device, recording device, and data
of delamination.
processing and interpretation equipment makes repeated
1.2 The most serious form of deterioration is that which is
passes, parallel to centerline across an asphalt covered bridge
caused by corrosion of embedded reinforcement. Corrosion is
deck at specified locations. Bridge deck condition is quantified
initiated by deicing salts, used for snow and ice control in the
based on the data obtained.
winter months, penetrating the concrete. In arid climates, the
corrosion can be initiated by chloride ions contained in the mix
3. Significance and Use
ingredients.
3.1 This test method provides information on the condition
1.2.1 As the reinforcing steel corrodes, it expands and
of concrete bridge decks overlaid with asphaltic concrete
creates a crack or subsurface fracture plane in the concrete at
without necessitating removal of the overlay, or other destruc-
or just above the level of the reinforcement. The fracture plane,
tive procedures.
or delamination, may be localized or may extend over a
3.2 A systematic approach to bridge deck rehabilitation
substantial area, especially if the concrete cover to the rein-
requires considerable data on the condition of the decks. In the
forcement is small. It is not uncommon for more than one
past, data has been collected using the traditional methods of
delamination to occur on different planes between the concrete
visual inspection supplemented by physical testing and coring.
surface and the reinforcing steel. Delaminations are not visible
Such methods have proven to be tedious, expensive and of
on the concrete surface. However, if repairs are not made, the
limited accuracy. Consequently, radar provides a mechanism to
delaminations progress to open spalls and, with continued
rapidly survey bridges in a non-contact, non-destructive man-
corrosion, eventually affect the structural integrity of the deck.
ner.
1.3 This test method may not be suitable for evaluating
3.3 Information on the condition of asphalt-covered, con-
bridges with delaminations which are localized over the
crete bridge decks is needed to estimate bridge deck condition
diameter of the reinforcement, or for those bridges which have
for maintenance and rehabilitation, to provide cost-effective
cathodic protection (coke breeze as cathode) installed on the
information necessary for rehabilitation contracts.
bridge or for which a conductive aggregate has been used in the
asphalt (that is, blast furnace slag). This is because metals are
4. Apparatus
perfect reflectors of EM waves, since the wave impedances for
4.1 Radar System—Air-coupled, short-pulse monostatic ra-
metals are zero.
dar(s) with a monocycle pulse, 150 mm (6 in.) free space
1.4 The values stated in SI units are to be regarded as the
resolution and a 50 scan/s data rate, minimum.
standard. The inch-pound units given in parentheses are for
4.2 Data Acquisition System—A data acquisition system,
information only. Specific precautionary statements are given
consisting of equipment for gathering radar data at the maxi-
in Section 5.
mum data rate of the radar system(s), 50 kHz for one radar, 100
1.5 This standard does not purport to address all of the
kHz for two radars, and 150 kHz for three radars. The system
safety concerns, if any, associated with its use. It is the
shall be capable of accurately acquiring radar data with a 60 dB
responsibility of the user of this standard to establish appro-
dynamic range.
4.3 Distance Measurement System—A distance measure-
This test method is under the jurisdiction of ASTM Committee D04 on Road
ment system consisting of a fifth-wheel or appropriate distance
and Paving Materials and is the direct responsibility of Subcommittee D04.32 on
measurement instrument (DMI) with accuracy of 6100
Bridges and Structures.
Current edition approved March 10, 1997. Published October 1998. Originally mm/km (6 6.5 in./mile) and a resolution of 25 mm (1 in.).
published as D 6087–97. Last previous edition D 6087–97.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6087
4.4 Test Vehicle—A vehicle with all equipment necessary to 6.2.1.1 Signal to Noise Ratio Test—Position the antenna at
perform the test and proper warning and safety devices
its far field distance approximately equal to maximum dimen-
installed. sion of antenna aperture above a square metal plate with a
width of 43 antenna aperture, minimum. Turn on the radar unit
NOTE 1—Fig. 1 shows a functional block diagram for multiple radars
and allow to operate for a 20 min warm up period or the time
and support equipment. Real-time digital data acquisition and high-speed
recommended by the manufacturer. After warming up the unit,
radar signal processing equipment and software have been designed
around the Penetradar Model PS-24 radar system to meet the needs of record 100 waveforms. Then evaluate the recorded waveform
this test method.
for signal to noise ratio. The signal to noise ratio is described
by the following equation:
5. Hazards
Signal Level ~A !
mp
5.1 During operation of the radar system, observe the
. 20 ~26.0 dB! (1)
Noise Level A
~ !
n
manufacturer’s safety directions at all times. When conducting
6.2.1.2 This will be performed on each of the 100 wave-
inspections ensure that appropriate traffic protection is utilized
in accordance with accepted standards. forms and the average signal to noise value of the 100
waveforms will be taken as the “signal to noise of the system.”
6. Procedure
Noise voltage (A ) is defined as the maximum amplitude
n
occurring between metal plate reflection and region up to 50 %
6.1 Conditions for Testing:
of the time window after the metal plate reflection, normally
6.1.1 If soil, aggregate, or other particulate debris is present
used with the antenna (that is, 1.0 GHz/20 ns: 10 ns.). The
on the bridge deck surface, clean the bridge deck.
signal level (A ) is defined as the amplitude of the echo from
6.1.2 Test the bridge deck in a surface dry condition.
mp
the metal plate.
6.2 System Performance Compliance—Conduct a test on
the radar equipment to ensure proper performance, at least
6.2.1.3 The signal to noise ratio test results for the GPR unit
once per year, or after periods of prolonged storage, or in
should be greater than or equal to 20 (+26.0 dB).
accordance with manufacturers recommendations. This test
6.2.2 Signal Stability:
shall consist of the following:
6.2.2.1 Signal Stability Test—Use the same test configura-
6.2.1 Signal to Noise Ratio:
tion as described in the signal to noise ratio test. Record 100
traces at the maximum data acquisition rate. Evaluate the
signal stability using the following equation:
Information regarding availability, use, or licensing of this product may be
A – A
max min
obtained from Penetradar Corporation, 2509 Niagara Falls Boulevard, PO Box 246, , 0.01 1% (2)
~ !
A
avg
Niagara Falls, NY 14304.
FIG. 1 Block Diagram of Radar and Support Equipment
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 6087
of the emitted energy to be used in subsequent measurements,
where:
and as a template for decorrelation.
A = the maximum amplitude of the metal plate reflec-
max
6.4 Radar Data Acquisition:
tion for all 100 traces,
6.4.1 Make radar inspection passes in a longitudinal direc-
A = the minimum amplitude of the metal plate reflec-
...