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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 Technology page.
 


Free Brochure
 Click here to download a 9-page brochure (.pdf format) on the impact-echo method and our equipment.
 


Instrument Components
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 instrument configurations.

    1.      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.

    2.      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.

    3.      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.

    4.      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 channels).

    5.      Notebook Computer: any standard notebook with Windows operating system is suitable (see Specifications page); instruments can be purchased with or without a computer.

    6.      Computer Software: user-friendly, Windows-based Impact-E software (on CD) analyzes signals, performs calculations, and displays test results on computer screen.

    7.      Two BNC Cables: for connecting transducer units to data acquisition system.

    8.      Serial/USB Port Cable: for connecting data acquisition system to serial port or USB port of computer.

    9.      Battery Charger: input 90v - 264v AC, output 12v DC, for recharging batteries and providing power for data acquisition system.

    10.  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).

    11.  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 warranty.

    12.   Roll-On/Carry-On Case (see Specifications page).

     

 New Wireless System for 2-Man Forensic Teams


Click Here for Detailed Information

Transducer Units

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. A test instrument must have at least one of these transducers.

          

Dual-Head: 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).

                              
                                    Dual-Head Transducer


Instrument Configurations
 

Three recommended configurations for an impact-echo test system, depending on the types of tests to be performed, are the following:

System A: A 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 (computer optional).

System B: A 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 C: A 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 performed.

The 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.


 

 

 

 

 

 

 

 

 

 

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