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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Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. It is available on a consulting basis through our sister company, Olson Engineering. 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.
The peak at 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.
Docter | GERMANN
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.
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.
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. 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.
Measure the thickness of pavements, asphalt overlays, slabs-on-ground and walls Detect the presence and depth of voids and honeycombing Detect voids below slabs-on-ground Evaluate the quality of grout injection in post-tensioning cable ducts Integrity of a membrane below an asphalt overlay protecting structural concrete Delamination surveys of bridge decks, piers, cooling towers and chimneystacks Detect debonding of overlays and patches Detect ASR damage and freezing-and-thawing damage Measure the depth of surface-opening cracks Estimate early-age strength development with proper correlation Principle A short-duration stress pulse is introduced into the member by mechanical impact.
The P-wave is then reflected back into the member and the cycle begins again. The thickness T of the member is related to this thickness frequency f and wave speed Cp by this simple approximate equation see below: 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. The thickness is calculated from this measured frequency and the P-wave speed obtained from Procedure A.
ASTM C Standard
Proceed to Checkout Continue Shopping. This assumes that the P-wave speed is uniform with depth. 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.
Furthermore, it is not possible to determine the depth to anomalies. This makes the impact-echo method inherently powerful aetm detecting air interfaces, such as those due to delaminations, cavities, and honeycombed concrete. The diffracted P-wave is detected by the transducer on the opposite side of the crack from the impact.
Detection of delaminations and honeycomb in sewer pipe. When the P-wave reaches the tip of the crack, the crack tip acts as a P-wave source, a process called diffraction.
NDT System Add-On — Impact Echo
The explanation for this 0. Work Item s – proposed revisions of this standard. Zstm the P-wave reaches the back side of the member, it is reflected and travels back to the surface where the impact was generated. Accurate measurement of thickness requires knowledge of the in-place P-wave speed. As the voice of the U. The frequency associated with the portion of the P-wave that travels around the defect c133 be shifted to a lower frequency value aetm the solid plate thickness frequency.
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. DOCter Purpose 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.
Thus the P-wave undergoes multiple reflections between the two surfaces. The P-wave speed is determined by testing over a solid portion of a plate with known thickness. 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 aztm. The figure is an example of the measurement of P-wave speed by using two transducers a known distance apart.
The Viking software allows the user to place cursors at the points corresponding to the P-wave arrivals, and calculates the value of Cp. 1c383 here for Agents.
If the defect is just large enough to be detectable, the amplitude spectrum will show two peaks: Already Subscribed to this document. These minimum lateral dimensions are necessary to prevent other modes 3 of vibration from interfering with the identification of the thickness mode frequency in the amplitude spectrum.
The time of arrival of the P-wave at each transducer is determined as the point when the signal for each transducer rises above the background value. This impact generated three types of stress waves that propagate away from the impact point. We have no amendments or corrections for this standard.
A sensitive displacement transducer next to the impact point picks up the disturbance due to the arrival of the P-wave. The DOCter is a versatile, portable system based on the impact-echo method, and can be used for the following applications: Active view current version of standard.
The frequency shift is a good indicator of the presence of a flaw if it is known that the plate thickness is constant. 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: A short-duration stress pulse is introduced into the member by mechanical impact.
These drawbacks are eliminated by using the impact-echo method, which requires access to only one surface. The thickness is calculated from this measured frequency and the P-wave speed obtained from Procedure A. The upper plot in this example shows the surface displacement waveform obtained from a test of a solid concrete slab.
If test equipment is assembled by the user, thickness limitations shall be established and documented. You may delete a document from your Alert Profile at any time. If the document is revised or amended, you will be notified by email.
Olson c133 Impact Echo systems for use with three different platforms as shown in the chart below. These notes and footnotes excluding those in tables and figures shall not be considered as requirements of the standard. 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 asstm of the interface.