1、Designation: C597 09Standard Test Method forPulse Velocity Through Concrete1This standard is issued under the fixed designation C597; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenthese
2、s indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This test method covers the determination of the propa-gation velocity of
3、 longitudinal stress wave pulses throughconcrete. This test method does not apply to the propagation ofother types of stress waves through concrete.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not p
4、urport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2
5、C125 Terminology Relating to Concrete and Concrete Ag-gregatesC215 Test Method for Fundamental Transverse, Longitudi-nal, and Torsional Resonant Frequencies of ConcreteSpecimensC823 Practice for Examination and Sampling of HardenedConcrete in ConstructionsE1316 Terminology for Nondestructive Examina
6、tions3. Terminology3.1 DefinitionsRefer to Terminology C125 and the sec-tion related to ultrasonic examination in Terminology E1316for definitions of terms used in this test method.4. Summary of Test Method4.1 Pulses of longitudinal stress waves are generated by anelectro-acoustical transducer that
7、is held in contact with onesurface of the concrete under test. After traversing through theconcrete, the pulses are received and converted into electricalenergy by a second transducer located a distance L from thetransmitting transducer. The transit time T is measured elec-tronically. The pulse velo
8、city V is calculated by dividing L byT.5. Significance and Use5.1 The pulse velocity, V, of longitudinal stress waves in aconcrete mass is related to its elastic properties and densityaccording to the following relationship:V 5E 1 2 !r 1 1 !1 2 2 !(1)where:E = dynamic modulus of elasticity, = dynami
9、c Poissons ratio, andr = density.5.2 This test method is applicable to assess the uniformityand relative quality of concrete, to indicate the presence ofvoids and cracks, and to evaluate the effectiveness of crackrepairs. It is also applicable to indicate changes in the proper-ties of concrete, and
10、in the survey of structures, to estimate theseverity of deterioration or cracking. When used to monitorchanges in condition over time, test locations are to be markedon the structure to ensure that tests are repeated at the samepositions.5.3 The degree of saturation of the concrete affects the pulse
11、velocity, and this factor must be considered when evaluatingtest results (Note 1). In addition, the pulse velocity in saturatedconcrete is less sensitive to changes in its relative quality.NOTE 1The pulse velocity in saturated concrete may be up to 5 %higher than in dry concrete.35.4 The pulse veloc
12、ity is independent of the dimensions ofthe test object provided reflected waves from boundaries do notcomplicate the determination of the arrival time of the directlytransmitted pulse. The least dimension of the test object mustexceed the wavelength of the ultrasonic vibrations (Note 2).NOTE 2The wa
13、velength of the vibrations equals the pulse velocity1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.64 on Nondestructive and In-Place Testing.Current edition approved Dec. 15, 2009. Published Feb
14、ruary 2010. Originallyapproved in 1967. Last previous edition approved in 2002 as C59702. DOI:10.1520/C0597-092For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the st
15、andards Document Summary page onthe ASTM website.3Bungey, J. H., Testing of Concrete in Structures, 2nd ed., Chapman and Hall,1989, p. 52.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2
16、959, United States.divided by the frequency of vibrations. For example, for a frequency of 54kHz and a pulse velocity of 3500 m/s, the wavelength is 3500/54000 =0.065 m.5.5 The accuracy of the measurement depends upon theability of the operator to determine precisely the distancebetween the transduc
17、ers and of the equipment to measureprecisely the pulse transit time. The received signal strengthand measured transit time are affected by the coupling of thetransducers to the concrete surfaces. Sufficient coupling agentand pressure must be applied to the transducers to ensure stabletransit times.
18、The strength of the received signal is also affectedby the travel path length and by the presence and degree ofcracking or deterioration in the concrete tested.NOTE 3Proper coupling can be verified by viewing the shape andmagnitude of the received waveform. The waveform should have adecaying sinusoi
19、dal shape. The shape can be viewed by means of outputsto an oscilloscope or digitized display inherent in the device.5.6 The results obtained by the use of this test method arenot to be considered as a means of measuring strength nor asan adequate test for establishing compliance of the modulus ofel
20、asticity of field concrete with that assumed in the design. Thelongitudinal resonance method in Test Method C215 is recom-mended for determining the dynamic modulus of elasticity oftest specimens obtained from field concrete because Poissonsratio does not have to be known.NOTE 4When circumstances pe
21、rmit, a velocity-strength (or velocity-modulus) relationship may be established by the determination of pulsevelocity and compressive strength (or modulus of elasticity) on a numberof samples of a concrete. This relationship may serve as a basis for theestimation of strength (or modulus of elasticit
22、y) by further pulse-velocitytests on that concrete. Refer to ACI 228.1R4for guidance on theprocedures for developing and using such a relationship.5.7 The procedure is applicable in both field and laboratorytesting regardless of size or shape of the specimen within thelimitations of available pulse-
23、generating sources.NOTE 5Presently available test equipment limits path lengths toapproximately 50-mm minimum and 15-m maximum, depending, in part,upon the frequency and intensity of the generated signal. The upper limitof the path length depends partly on surface conditions and partly on thecharact
24、eristics of the interior concrete under investigation. A preamplifierat the receiving transducer may be used to increase the maximum pathlength that can be tested. The maximum path length is obtained by usingtransducers of relatively low resonant frequencies (20 to 30 kHz) tominimize the attenuation
25、 of the signal in the concrete. (The resonantfrequency of the transducer assembly determines the frequency ofvibration in the concrete.) For the shorter path lengths where loss of signalis not the governing factor, it is preferable to use resonant frequencies of50 kHz or higher to achieve more accur
26、ate transit-time measurements andhence greater sensitivity.5.8 Since the pulse velocity in steel is up to double that inconcrete, the pulse-velocity measured in the vicinity of thereinforcing steel will be higher than in plain concrete of thesame composition. Where possible, avoid measurements close
27、to steel parallel to the direction of pulse propagation.6. Apparatus6.1 The testing apparatus, shown schematically in Fig. 1,consists of a pulse generator, a pair of transducers (transmitterand receiver), an amplifier, a time measuring circuit, a timedisplay unit, and connecting cables.6.1.1 Pulse G
28、enerator and Transmitting TransducerThepulse generator shall consist of circuitry for generating pulsesof voltage (Note 6). The transducer for transforming theseelectronic pulses into wave bursts of mechanical energy shallhave a resonant frequency in the range from 20 to 100 kHz(Note 7). The pulse g
29、enerator shall produce repetitive pulses ata rate of at least 3 pulses per second. The time interval betweenpulses shall exceed the decay time for the transmitting trans-ducer. The transducer shall be constructed of piezoelectric,magnetostrictive, or other voltage-sensitive material, andhoused for p
30、rotection. A triggering pulse shall be produced tostart the time measuring circuit.NOTE 6The pulse voltage affects the transducer power output and themaximum penetration of the longitudinal stress waves. Voltage pulses of500 to 1000 V have been used successfully.NOTE 7Transducers with higher resonan
31、t frequencies have been usedsuccessfully in relatively small laboratory specimens.6.1.2 Receiving Transducer and AmplifierThe receivingtransducer shall be similar to the transmitting transducer. Thevoltage generated by the receiver shall be amplified as neces-sary to produce triggering pulses to the
32、 time-measuring circuit.The amplifier shall have a flat response between one half andthree times the resonant frequency of the receiving transducer.6.1.3 Time-Measuring CircuitThe time-measuring circuitand the associated triggering pulses shall be capable ofproviding an overall time-measurement reso
33、lution of at least 1s. Time measurement is initiated by a triggering voltage fromthe pulse generator, and the time measuring circuit shalloperate at the repetition frequency of the pulse generator. Thetime-measuring circuit shall provide an output when thereceived pulse is detected, and this output
34、shall be used to4“In-Place Methods to Estimate Concrete Strength,” ACI 228.1R, AmericanConcrete Institute, Farmington Hills, MI.NOTE 1It is advantageous to incorporate the pulse generator, timemeasuring circuit, receiver amplifier, and time display into one unit.FIG. 1 Schematic of Pulse Velocity Ap
35、paratusC597 092determine the transit time displayed on the time-display unit.The time-measuring circuit shall be insensitive to operatingtemperature in the range from 0 to 40C and voltage changesin the power source of 615 %.6.1.4 Display UnitA display unit shall indicate the pulsetransit time to the
36、 nearest 0.1 s.6.1.5 Reference BarFor units that use manual zero-timeadjustment, provide a bar of metal or other durable material forwhich the transit time of longitudinal waves is known. Thetransit time shall be marked permanently on the reference bar.The reference bar is optional for units that pe
37、rform automaticzero-time adjustment.6.1.6 Connecting CablesWhere pulse-velocity measure-ments on large structures require the use of long interconnect-ing cables, use low-capacitance, shielded, coaxial cables.6.1.7 Coupling AgentA viscous material (such as oil,petroleum jelly, water soluble jelly, m
38、oldable rubber, or grease)to ensure efficient transfer of energy between the concrete andthe transducers. The function of the coupling agent is toeliminate air between the contact surfaces of the transducersand the concrete. Water is an acceptable coupling agent whenponded on the surface, or for und
39、erwater testing.7. Procedure7.1 Functional Check of Equipment and Zero-timeAdjustmentVerify that the equipment is operating properlyand perform a zero-time adjustment.7.1.1 Units with Automatic Zero-Time AdjustmentApplycoupling agent to the transducer faces and press the facestogether. The instrumen
40、t uses a microprocessor to record thisdelay time, which is subtracted automatically from subsequenttransit time measurements.NOTE 8A reference bar may be used to verify that the zero-timeadjustment has been performed correctly.7.1.2 Units with Manual Zero-Time AdjustmentApplycoupling agent to the en
41、ds of the reference bar, and press thetransducers firmly against the ends of the bar until a stabletransit time is displayed. Adjust the zero reference until thedisplayed transit time agrees with the value marked on the bar.7.1.3 Check the zero adjustment on an hourly basis duringcontinuous operatio
42、n of the instrument, and every time atransducer or connecting cable is changed. If zero-time adjust-ment cannot be accomplished, do not use the instrument untilit has been repaired.7.2 Determination of Transit Time:7.2.1 For testing existing construction, select test locationsin accordance with Prac
43、tice C823, or follow the requirementsof the party requesting the testing, whichever is applicable.7.2.2 For best results, locate the transducers directly oppo-site each other. Because the beam width of the vibrationalpulses emitted by the transducers is large, it is permissible tomeasure transit tim
44、es across corners of a structure but withsome loss of sensitivity and accuracy. Measurements along thesame surface shall not be used unless only one face of thestructure is accessible since such measurements may be indica-tive only of surface layers, and calculated pulse velocities willnot agree wit
45、h those obtained by through transmission (Note9).NOTE 9One of the sources of uncertainty in surface tests is thelengths of the actual travel paths of the pulses. Hence, individual readingsare of little value. Surface tests, however, have been used to estimate thedepth of a lower quality surface laye
46、r by making multiple measurementsof transit time with varying distances between the transducers. From theplot of travel time versus spacing, it may be possible to estimate the depthof the lower quality concrete.57.2.3 Apply an appropriate coupling agent (such as water,oil, petroleum jelly, grease, m
47、oldable rubber, or other viscousmaterials) to the transducer faces or the test surface, or both.Press the faces of the transducers firmly against the surfaces ofthe concrete until a stable transit time is displayed, andmeasure the transit time (Note 10). Determine the straight-linedistance between c
48、enters of transducer faces.NOTE 10The quality of the coupling is critically important to theaccuracy and maximum range of the method. Inadequate coupling willresult in unstable and inaccurate time measurements, and will significantlyshorten the effective range of the instrument. Repeat measurements
49、shouldbe made at the same location to minimize erroneous readings due to poorcoupling.8. Calculation8.1 Calculate the pulse velocity as follows:V 5 L/T (2)where:V = pulse velocity, m/s,L = distance between centers of transducer faces, m, andT = transit time, s.9. Report9.1 Report at least the following information:9.1.1 Location of test or identification of specimen.9.1.2 Location of transducers.9.1.3 Distance between centers of transducer faces, reportedto a precision of at least 0.5 % of the distance.9.1.4 Transit time, reported to a resolution of
