Visits since 5 Sep 05:
Our products measure the thickness of concrete plates
and slabs according to ASTM Standard C 1383-98a.
They can also measure the depth of surface-opening
cracks and determine the location, depth and extent
of cracks, voids, delaminations, honeycombing and
debonding in plain and reinforced structures. For a
description of the method, see our
Click here to download
a 9-page brochure (.pdf format) on the impact-echo
method and our equipment.
The picture and numbered
list below describe all components available for an impact-echo instrument.
Configuring an instrument consists in selecting the number and types of
transducers (items 2-3). The transducers are described below, together with suggested
Impactors: a set of 10
hardened steel spheres on spring rods, used to generate the
stress waves that propagate within the structure and are reflected by flaws
or external surfaces.
Hand-Held Transducer Units:
the cylindrical and pistol grip models are used to detect
signals generated by multiple reflections of stress waves within a
structure. See photographs and descriptions below.
Dual-Head Transducer: used
to measure wave speed by recording the travel time of a stress wave between
two transducer elements held at a fixed distance (300mm) on the surface of a
structure. See photograph and description below.
Analog/Digital Data Acquisition System: receives and
digitizes voltage-time signals from the transducers, and sends them to
computer (14-bit resolution, 2 MHz maximum sampling speed on each of two
Notebook Computer: any standard notebook with
Windows operating system is suitable (see
Specifications page); instruments can be purchased with or without a
user-friendly, Windows-based Impact-E
software (on CD) analyzes signals,
performs calculations, and displays test results on computer screen.
Two BNC Cables: for connecting transducer units to
data acquisition system.
Serial/USB Port Cable: for connecting data
acquisition system to serial port or USB port of computer.
Battery Charger: input 90v - 264v AC, output
12v DC, for recharging batteries and providing power for data acquisition system.
DC Power Supply:
input 6 -24v DC, output 12v DC, for recharging batteries in data acquisition
system (connects to cigarette lighter in car or truck).
Printed Materials: Book:
"Impact-Echo: Nondestructive Evaluation of Concrete and Masonry"
by M. J. Sansalone and W. B. Streett, Bullbrier Press, Ithaca, NY, 1997,
339pp; instruction manuals; and other documents, including packing list and
Roll-On/Carry-On Case (see
New Wireless System for 2-Man Forensic Teams
Here for Detailed Information
Pistol Grip and Cylindrical: Two types of transducers
are available for routine impact-echo testing. For a description of the
functioning of the transducer, see the Technology
page. After the transducer is put in place on the test surface it is armed by
depressing a trigger or button. The pistol grip transducer (directly below) is
armed with a trigger on the underside of the handle. It is the easiest to use
and is especially well suited to flat surfaces. The cylindrical transducer
(lower two images) is armed by depressing the yellow button on one end of the
handle. It is useful for testing in narrow and confined surfaces.
test instrument must have at least one of these transducers.
Accurate measurements of depth and thickness require knowledge of the wave speed
(speed of sound) in concrete, which can vary from about 3000 to 6000 meters/sec,
depending on concrete quality and type of aggregate.
The dual-head transducer shown below is used only for independent measurements
of wave speed (required for determining plate or slab thickness in accordance
with ASTM Standard
C 1383-98a). It cannot be used for impact-echo testing. Wave
speed can be measured using a single cylindrical or pistol grip transducer only
if tests can be performed on a slab of precisely known thickness in the region
of the structure where testing will be carried out (not acceptable under ASTM
Standard C 1383-98a).
recommended configurations for an impact-echo test system, depending on the
types of tests to be performed, are the following:
system three transducers including two cylindrical or two pistol grip or one of
each, plus a dual-head transducer. The cylindrical and pistol grip transducers
can be used for testing, with a backup available in case one is lost or damaged.
Determining the depth of surface-opening cracks requires two transducers, and is
most convenient using two cylindrical or two pistol grip transducers, or one of
each. The dual-head transducer is used for independent measurements of wave
speed. The picture at the top of this page shows the components of this system
system that includes one transducer for testing, either cylindrical or pistol
grip, and one dual-head wave speed transducer. This will cover all possible
testing needs. For determining the depth of surface-opening cracks, one end of
the dual-head transducer can be used in conjunction with the pistol grip or
cylindrical transducer; however this can be cumbersome in some situations. The
dual-head transducer is used for independent measurements of wave speed
system that includes only one transducer, either cylindrical or pistol grip.
This system is suitable for routine testing. Wave speed can be measured only if
tests can be performed on slabs of known thickness in the regions where testing is to be
photographs below show the main components used for routine impact-echo testing
(top) and for independent measurements of wave speed (bottom).
Configuration for Testing
Configuration for Wave Speed Measurement
To measure wave speed, an impact is made on the straight line between the two
transducer tips, and the time required for a stress wave
to travel the fixed distance (300mm) between the two
transducers is measured. For concrete with a wave speed
of 4000 m/s, this travel time is
75 micro-seconds. To achieve 1% to 2% accuracy the
wave arrival times must be measured to within about 0.5
micro-seconds (0.0000005 sec). This requires a sampling
rate of at least 2 MHz (2 million samples per second)
which is provided by our data acquisition system.
Wireless Echo System: A
system designed for 2-man forensic teams. One
operator performs tests on a structure (bridge,
building, etc) and the resulting test signals are sent
wirelessly (up to 300M) to the computer, which is
monitored continuously by the second operator. Two-way
radios are provided for continuous voice contact between
the two operators.
Click Here to
view details of the new Wireless Echo System.
ASTM Standard C 1383-98a
The instrument in the two
configurations shown above can measure
P-wave speed and concrete thickness according to Standard C 1383-98a,
"Standard Test Method for Measuring the P-Wave Speed and
the Thickness of Concrete Plates Using the Impact-Echo
Method", published by the AMERICAN SOCIETY FOR TESTING
AND MATERIALS (ASTM).
Specifications & Warranty:
Click Here to view
specifications for our instruments.
Click here to view warranty
and compliance provisions.