This standard is issued under the fixed designation C ; the number 1 This test method is under the jurisdiction of ASTM Committee C-9 on Concrete. Purchase your copy of ASTM C – 15 as a PDF download or hard copy directly from the official BSI Shop. All BSI British Standards available. mm. Thickness Measurement by ASTM C Accurate measurement of thickness requires knowledge of the in-place P- wave speed. ASTM C, “Test .
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Impact-Echo TestThis procedure measures the frequency at which the P-wave generated by a short-duration, point impact is reflected between the parallel opposite surfaces of a plate. The displacement waveform is transformed into the frequency domain to produce an amplitude spectrumwhich shows the predominant frequencies in the waveform. The following lists the reflection coefficients of a P-wave travelling through concrete and incident normal to an interface with air, water, soil, or steel:.
This is because the wave has to travel a longer distance as it diffracts around the flaw. The thickness is calculated from this measured frequency and the P-wave speed obtained from Procedure A. The absolute systematic error depends on the plate thickness, the sampling interval, and the sampling period. The thickness T of the member is related to this thickness frequency f and wave speed Cp by this simple approximate equation see below: If the area of the reflecting interface is large, the impact-echo response will be similar to that of a solid plate except that the thickness frequency will be shifted to the higher value corresponding to the depth of the interface.
The figure below the waveform is the amplitude spectrum obtained by transforming the waveform into the frequency domain. The figure is an example of the measurement of P-wave speed by using two transducers a known distance apart.
The DOCter is a versatile, portable system based on the impact-echo method, and can be used for the following applications:. P-Wave Speed Measurement— This procedure measures the time it takes for the P-wave generated by a short-duration, point impact to travel between two transducers positioned a known distance apart along the surface of a structure. Complete Docter Brochure Docter Publications. As explained in Note 12the minimum lateral dimensions and acceptable sampling period are related.
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. Impact Echo IE investigations are performed to assess the condition or thickness of slabs, beams, columns, walls, pavements, runways, tunnels, and dams. The recorded waveform of surface displacement has a periodic pattern that is related to the thickness of the member and the wave speed.
The frequency content covered by the Spider impactors is approximately 1. Testing for quality of grout injection in cable ducts located by ground penetrating radar. The equation on page 50 is used to solve for Cpi. You can download and open this file to your own computer but DRM prevents opening this file on another computer, including a networked server.
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.
This assumes that the P-wave speed is uniform with depth.
The use of traditional stress wave methods, such as ultrasonic through transmission, to identify the presence of anomalies in structures requires access to both faces of a member.
When the P-wave reaches the tip of the crack, the crack tip acts as a P-wave source, a process called diffraction. If the document is revised or amended, you will be notified by email. The system includes a laptop computer, a data acquisition module, one Mark IV transducer with impactors, and software.
This standard is also available to be included in Standards Subscriptions. The P-wave speed is determined by testing over a solid portion of a plate with known thickness. Contact Olson Instruments when adding on to an existing system, or purchasing multiple systems as some of the components are common to other test methods.
Depth of Surface-Opening Cracks The DOCter can also be used to measure the depth of surface-opening cracks, using a time domain analysis. The asfm of P-wave arrival is determined as the frequency with a high peak in the amplitude spectrum.
Olson offers Impact Echo systems for use asgm three different platforms as shown in the chart below. It is seen that at a concrete-air interface, there is complete reflection of the P-wave. It is the responsibility of the user of this standard to establish appropriate safety and health practices and adtm the applicability of regulatory limitations prior to use.
The limits shall be specified by manufacturer of the apparatus, and the apparatus shall not be used beyond these limits. One method is by determining the thickness frequency and then measuring the actual plate asmt at that point. Thus, the impact-echo method is able to determine the location of internal defects as well as measure the thickness of a solid member.
The distance L mm between the transducers, is divided by time difference t between arrival of the P-wave at the second and first transducers. CTG-2 requires Windows Device. If test equipment is assembled by the user, thickness limitations shall be established and documented. All of Olson Instruments have been researched, tested, and used on-site daily by our sister company, Olson Atmworld reknowned for NDT consulting. The Spider is placed adjacent to the Mark IV transducer as shown in the photo.
It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the asgm of regulatory limitations prior to use.
ASTM C Standard
A short-duration stress pulse is introduced into the member by mechanical impact. The Spider multiple impactor unit can be purchased as an option to increase the operating range of the systems. Click here for Agents. You may delete a document from your Alert Profile at any time. The DOCter is a versatile, portable system based on the impact-echo method, and can be used for the following applications: Example The upper plot in this example shows the surface displacement waveform obtained from a test of a solid concrete slab.
NDT System Add-On — Impact Echo
The method astj based on the assumption that the concrete plate has the same P-wave speed throughout its depth. Please first log in with a verified email before subscribing to alerts. Standards Subscriptions from ANSI provides a money-saving, multi-user solution for accessing standards. These notes and footnotes excluding those in tables and figures shall not be considered as requirements of the standard.