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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A sensitive displacement transducer next to the impact point picks up the disturbance due to the arrival of the P-wave. As the voice of the U. These notes and footnotes excluding those in tables and figures shall not be considered as requirements of the standard. Measurement of P-wave Speed The figure is an example of the measurement of P-wave speed by using two transducers a known distance apart.
Add to Alert PDF. The OE Website is loaded with Tech Brief and project photos using the equipment shown on this website. One method is by determining the thickness frequency and then measuring the actual plate thickness at that point.
By measuring the time interval between the arrival of the direct P -wave at the first transducer and the arrival of the diffracted wave at the second transducer, the depth of the crack can be calculated. Please first log in with a verified email before subscribing to alerts. P-Wave Speed MeasurementThis 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.
These notes and footnotes excluding those in tables and figures shall not be considered as requirements of the standard. Lastly, the IE method will provide information on the depth of a flaw or defect, in addition to mapping its lateral location and extent.
If the wave speed is determined by the surface measurement method, the resulting value is multiplied by 0. The thickness T of the member is related to this thickness frequency f and wave speed Cp by this simple approximate equation see below: The thickness is calculated from this measured frequency and the P-wave speed obtained from Procedure A. Standards Subsctiption may be the perfect solution. No other units of measurement are included in this standard.
The recorded waveform of surface displacement has a periodic pattern that is related to the thickness of the member and the wave speed.
Link to Active This link will always route to the current Active version of the standard. The figure below the waveform is the amplitude spectrum obtained by transforming the waveform into the frequency domain.
Detection of Internal Defects The P-wave generated by impact will reflect at interfaces within the concrete where there is a change in acoustic impedancewhich is defined as the product of the density and wave speed of a material.
Thus the P-wave undergoes multiple reflections between the two surfaces. The Spider multiple impactor unit can wstm purchased as an option to increase the operating range of the systems.
Docter | GERMANN
The frequency shift is a good v1383 of the presence of a flaw if it is known that the plate thickness is c11383. 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.
Need more than one copy? The LONGSHIP transducers are placed on opposite sides of the crack as shown in the sketch to the right and impact is generated on the line passing through the transducers. This makes the impact-echo method inherently powerful for detecting air interfaces, such as those due to delaminations, cavities, and honeycombed concrete.
When the P-wave reaches the tip of the crack, the crack tip acts as a P-wave source, a process called diffraction. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.
CTG-2 requires Windows Device. The frequency of P-wave arrival is determined as the frequency with a high peak in the amplitude spectrum.
All of Olson Instruments have been researched, tested, and used on-site daily by our sister company, Olson Engineeringworld reknowned for NDT consulting. 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. 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.
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This impact generated three types of stress waves that propagate away from the impact point. IE investigations can also be performed to predict the strength of early age concrete if the member thickness is known. This assumes that the P-wave speed is uniform with depth. Ashm 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.
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ASTM C Standard
A short-duration stress pulse is introduced into the member by mechanical impact. 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:.
The upper plot in this example shows the surface displacement waveform obtained from a test of a solid concrete slab. The P-wave speed is calculated by dividing the distance between the two transducers by the travel time.
ASTM C1383 – 15
If asmt document is revised or amended, you will be notified by email. Cracks Delaminations Honeycomb Thickness Voids. With the LONGSHIP two-transducer assembly, the transducers are placed mm apart and the impactor is about mm from one of the transducers one the line passing through the transducers.
The frequency associated with the portion of the P-wave that travels around the defect will be shifted to a lower frequency value than the solid plate thickness frequency.
As aztm in Note 12the minimum lateral dimensions and acceptable sampling period are related. The equation on page 50 is used to solve for Cpi. Thus the correct equation for thickness calculation is: The DOCter is a versatile, portable system based on the impact-echo method, asttm can be used for the following applications: The Viking software allows the user to place cursors at the points corresponding to the P-wave arrivals, and calculates the value of Cp.
Example The upper plot in this example shows the surface displacement waveform obtained from a test of a solid concrete slab.