1、Designation: C1383 04 (Reapproved 2010)C1383 15Standard Test Method forMeasuring the P-Wave Speed and the Thickness ofConcrete Plates Using the Impact-Echo Method1This standard is issued under the fixed designation C1383; the number immediately following the designation indicates the year oforiginal
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 This test method covers procedures for determining the thick
3、ness of concrete slabs, pavements, bridge decks, walls, or otherplate-like structure using the impact-echo method.1.2 The following two procedures are covered in this test method:1.2.1 Procedure A: P-Wave Speed MeasurementThis procedure measures the time it takes for the P-wave generated by ashort-d
4、uration, point impact to travel between two transducers positioned a known distance apart along the surface of a structure.The P-wave speed is calculated by dividing the distance between the two transducers by the travel time.1.2.2 Procedure B: Impact-Echo TestThis procedure measures the frequency a
5、t which the P-wave generated by ashort-duration, point impact is reflected between the parallel (opposite) surfaces of a plate. The thickness is calculated from thismeasured frequency and the P-wave speed obtained from Procedure A.1.2.3 Unless specified otherwise, both Procedure A and Procedure B mu
6、st be performed at each point where a thicknessdetermination is made.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 The text of this standard references notes and footnotes that provide explanatory material. These not
7、es and footnotes(excluding those in tables and figures) shall not be considered as requirements of the standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate saf
8、ety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C125 Terminology Relating to Concrete and Concrete AggregatesC597 Test Method for Pulse Velocity Through ConcreteE1316 Terminology for Nondestructive Examinations
9、3. Terminology3.1 Definitions:3.1.1 acoustic impedance, nthe product of P-wave speed and density that is used in computations of characteristics of stresswave reflection at boundaries.3.1.2 amplitude spectrum, na plot of relative amplitude versus frequency that is obtained from the waveform using a
10、Fouriertransform technique.3.1.3 Fourier transform, na numerical technique used to convert digital waveforms from the time domain to the frequencydomain.3.1.3.1 Discussion1 This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsi
11、bility of Subcommittee C09.64 onNondestructive and In-Place Testing.Current edition approved Dec. 15, 2010June 15, 2015. Published March 2011September 2015. Originally approved in 1998. Last previous edition approved in 20042010as C1383C1383 04 (2010).04. DOI: 10.1520/C1383-04R10.10.1520/C1383-15.2
12、For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to p
13、rovide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof t
14、he standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1The peaks in the amplitude spectrum correspond
15、 to the dominant frequencies in the waveform.3.1.4 impact-echo method, na send-receive nondestructive test method based on the use of a short-duration mechanical impactto generate transient stress waves and the use of a broadband receiving transducer placed adjacent to the impact point.3.1.4.1 Discu
16、ssionWaveforms are converted to the frequency domain and the resulting amplitude spectra are analyzed to obtain the dominantfrequencies in the structures response to the impact. These frequencies are used to determine the thickness of the structure or thepresence of flaws.3.1.5 impact duration, nthe
17、 time that the impactor used to generate stress waves is in contact with the test surface. Alsoreferred to as contact time.3.1.5.1 DiscussionThe impact duration is a critical aspect in the success of the two procedures covered by this method. Recommended impactdurations are given. In practice, the i
18、mpact duration will depend on the type of impactor and the condition of the concrete at thepoint of impact. Smooth, hard surfaces will result in shorter impact durations than rough, soft surfaces. The user should verify thatthe impact durations are within the recommended ranges. An approximate measu
19、re of the impact duration can be obtained fromthe portion of the waveform corresponding to the surface wave arrival.3Fig. 1 shows an example of the surface-wave portion ofa waveform and the approximate contact time is indicated.3.1.6 P-wave, nthe dilatational (longitudinal or primary) stress wave th
20、at causes particle displacement parallel to the directionof wave propagation. This wave produces normal stresses (tensile or compressive) as it propagates.3.1.7 P-wave speed, nthe speed with which the P-wave propagates through a semi-infinite solid.3.1.7.1 DiscussionThe P-wave speed is the same as t
21、he compressional pulse velocity measured according to Test Method C597.3.1.8 sampling frequency, nthe rate at which the points that comprise the waveform are recorded; the inverse of the samplinginterval, expressed in Hz or samples/s (also referred to as sampling rate).3.1.9 sampling period, nthe du
22、ration of the waveform, which equals the number of points in the waveform multiplied by thesampling interval.3.1.10 sampling interval, nthe time difference between any two adjacent points in the waveform.3 Sansalone, M. and Streett, W.B., Impact-Echo: Nondestructive Evaluation of Concrete and Masonr
23、y, Bullbrier Press, Ithaca, NY and Jersey Shore, PA, 1997.FIG. 13 Expanded View of Surface-Wave Portion of Waveform Showing the Width of the Surface Wave Signal as an Approximation ofthe Contact Time of the ImpactC1383 1523.1.11 surface wave, na stress wave in which the particle motion is elliptical
24、 and the amplitude of particle motion decreasesrapidly with depth. Also known as Rayleigh wave (or R-wave).3.1.12 waveform, na recorded signal from a transducer that is a plot of voltage versus time.3.1.1 Refer to TerminologyFor definitions of E1316 for additional definitions, related to nondestruct
25、ive ultrasonic examination,thatterms used in this test method, refer to Terminology C125 are applicableand Terminology E1316to this test method3.2 Definitions of Terms Specific to This Standard:3.2.1 acoustic impedance, nthe product of P-wave speed and density that is used in computations of charact
26、eristics of stresswave reflection at boundaries.3.2.2 P-wave, nthe dilatational (longitudinal or primary) stress wave that causes particle displacement parallel to the directionof wave propagation: this wave produces normal stresses (tensile or compressive) as it propagates.3.2.3 P-wave speed, nthe
27、speed with which the P-wave propagates through a semi-infinite solid.3.2.3.1 DiscussionThe P-wave speed is the same as the compressional pulse velocity measured according to Test Method C597.3.2.4 apparent P-wave speed in a plate3,4, na parameter wave speed that is equal to 0.96 of the P-wave speed:
28、C p,plate 50.96 Cp (1)where:Cp, plate = the apparent P-wave speed in a plate, m/s, andCp = the P-wave speed in concrete that is obtained from Procedure A, m/s.3.2.4.1 DiscussionThis parameter wave speed is used in thickness calculations in impact-echo measurements on plates. The P-wave speed in amat
29、erial (concrete)measured using Procedure A is converted to the apparent P-wave speed in a plate that is used to calculate theplate thickness by the following equation:T5Cp, plate2f (2)T5Cp, plate2f (2)where:T = the thickness of the plate, m, andf = the frequency of the P-wave thickness mode of the p
30、late obtained from the amplitude spectrum, Hz.If the alternative procedure in 9.6 is used to determine the apparent P-wave speed, the 0.96 factor is not applied to the determinedP-wave speed for calculating the thickness.3.2.5 plate, surface wave, nany prismatic structure where the lateral dimension
31、s are at least six times the thickness.a stresswave in which the particle motion is elliptical and the amplitude of particle motion decreases rapidly with depth: also known asRayleigh wave (or R-wave).3.2.2.1 DiscussionMinimum lateral dimensions are necessary to prevent plate modes3 of vibration fro
32、m interfering with the identification of thethickness mode frequency in the amplitude spectrum. The minimum lateral dimensions and acceptable sampling period are related,as explained in Note 11.4 Sansalone, M., Lin, J. M., and Streett, W. B., “AProcedure for Determining P-wave Speed in Concrete for
33、Use in Impact-Echo Testing Using P-wave Speed MeasurementTechnique,” ACI Journal, Vol. 94, No. 6, NovemberDecember 1997, pp. 531539.C1383 1534. Significance and Use4.1 This test method may be used as a substitute for, or in conjunction with, coring to determine the thickness of slabs,pavements, deck
34、s, walls, or other plate structures. There is a certain level of systematic error in the calculated thickness due to thediscrete nature of the digital records that are used. The absolute systematic error depends on the plate thickness, the samplinginterval, and the sampling period.4.2 Because the wa
35、ve speed can vary from point-to-point in the structure due to differences in concrete age or batch-to-batchvariability, the wave speed is measured (Procedure A) at each point where a thickness determination (Procedure B) is required.4.3 This test method is a pplicable to plate-like structures with l
36、ateral dimensions at least six times the thickness. Theseminimum lateral dimensions are necessary to prevent other modes3 of vibration from interfering with the identification of thethickness mode frequency in the amplitude spectrum. As explained in Note 12, the minimum lateral dimensions and accept
37、ablesampling period are related.4.4 The maximum and minimum thickness that can be measured is limited by the details of the testing apparatus (transducerresponse characteristics and the specific impactor).The limits shall be specified by manufacturer of the apparatus, and the apparatusshall not be u
38、sed beyond these limits. If test equipment is assembled by the user, thickness limitations shall be established anddocumented.4.5 This test method is not applicable to plate structures with overlays, such as a concrete bridge deck with an asphalt orportland cement concrete overlay. The method is bas
39、ed on the assumption that the concrete plate has the same P-wave speedthroughout its depth.4.6 Procedure A is performed on concrete that is air dry as high surface moisture content may affect the results.4.7 Procedure B is applicable to a concrete plate resting on a subgrade of soil, gravel, permeab
40、le asphalt concrete, or leanportland cement concrete provided there is sufficient difference in acoustic impedance3 between the concrete and subgrade or thereare enough air voids at the interface to produce measurable reflections. If these conditions are not satisfied, the waveform will beof low amp
41、litude and the amplitude spectrum will not include a dominant peak at the frequency corresponding to the thickness(Eq 2). If the interface between the concrete and subgrade is rough, the amplitude spectrum will have a rounded peak instead ofa sharp peak associated with a flat surface.4.8 The procedu
42、res described are not influenced by traffic noise or low frequency structural vibrations set up by normalmovement of traffic across a structure.4.9 The procedures are not applicable in the presence of mechanical noise created by equipment impacting (jack hammers,sounding with a hammer, mechanical sw
43、eepers, and so forth) on the structure.4.10 Procedure A is not applicable in the presence of high amplitude electrical noise, such as may produced by a generator orsome other source, that is transmitted to the data-acquisition system.PROCEDURE AP-WAVE SPEED MEASUREMENT5. Summary of Procedure5.1 An i
44、mpact on the concrete surface is used to generate transient stress waves. These waves propagate along the surface ofthe concrete past two transducers, placed on a line through the impact point and at a known distance apart.5.2 The time difference between the arrival of the P-wave (stress wave with h
45、ighest speed) at each transducer is used todetermine the P-wave speed by dividing the time difference (travel time) by the known distance between the transducers.6. Apparatus56.1 ImpactorThe impactor shall be spherical or spherically tipped. It shall produce an impact duration of 30 6 10 s withsuffi
46、cient energy to produce surface displacements due to the P-wave that can be recorded by the two transducers (see Note 1).The impactor shall be positioned to strike on the centerline passing through the two transducers at a distance of 150610 mm fromthe first transducer.NOTE 1Hardened steel balls ran
47、ging from 5 to 8 mm in diameter and attached to steel spring rods have been found to produce suitable impacts.6.2 TransducersTwo broadband transducers that respond to displacements normal to the surface. These transducers must becapable of detecting the small displacements that correspond to the arr
48、ival of the impact-generated P-wave traveling along thesurface.Asmall contact area between the piezoelectric element and the concrete surface is required to record accurately the arrivalof the P-wave (see Note 2). Use a suitable material to couple the transducer to the concrete.5 Suitable apparatus
49、is available commercially.C1383 154NOTE 2A commercially available displacement transducer made from a conical piezoelectric element with a tip diameter of 1.5 mm and the largerend attached to a brass backing block has been found suitable.6 A lead sheet approximately 0.25 mm thick is a suitable coupling material for such atransducer.6.2.1 Acceptable transducers shall be previously documented to produce accurate results for plate thicknesses similar to thosebeing measured by this test method.6.3 Spacer DeviceA spacer device shall be provided
