1、Designation: D 4695 03 (Reapproved 2008)Standard Guide forGeneral Pavement Deflection Measurements1This standard is issued under the fixed designation D 4695; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio
2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide provides procedural information for measur-ing pavement surface deflections, directly under, or at locationsradially ou
3、tward (offset) from a known static, steady-state, orimpulse load. Deflections are measured with sensors thatmonitor the vertical movement of a pavement surface due tothe load. This guide describes procedures for the deflectionmeasurement using various deflection testing devices andprovides the gener
4、al information that should be obtainedregardless of the type of testing device used.1.2 This guide is applicable for deflection measurementsperformed on flexible asphalt concrete (AC), rigid portlandcement concrete (PCC), or composite (AC/PCC) pavements.Rigid pavements may be plain, jointed, jointed
5、 reinforced, orcontinuously reinforced concrete.1.3 The values stated in SI units are to be regarded asstandard. Inch-pound units given in parentheses are for infor-mation purposes only.1.4 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toad
6、dress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 4602 Guide
7、for Nondestructive Testing of PavementsUsing Cyclic-Loading Dynamic Deflection EquipmentD 4694 Test Method for Deflections with a Falling-Weight-Type Impulse Load DeviceD 5858 Guide for Calculating In Situ Equivalent ElasticModuli of Pavement Materials Using Layered ElasticTheory2.2 AASHTO Standard:
8、3T256Standard Method of Test for Pavement DeflectionMeasurementsPDDX Pavement Deflection Data ExchangeTechnicalData Guide, Version 1.0, April 19983. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 deflection basin, nThe bowl shape of the deformedpavement surface due to a specifie
9、d load as depicted from thepeak measurements of a series of deflection sensors placed atradial offsets from the center of the load plate.3.1.2 deflection basin test, nA test with deflection sensorsplaced at various radial offsets from the center of the load plate.The test is used to record the shape
10、 of the deflection basinresulting from an applied load. Information from this test canbe used to estimate material properties for a given pavementstructure.3.1.3 deflection sensor, nElectronic device(s) capable ofmeasuring the relative vertical movement of a pavementsurface and mounted in such a man
11、ner as to minimize angularrotation with respect to its measuring plane at the expectedmovement. Such devices may include seismometers, velocitytransducers, or accelerometers.3.1.4 load cell, nCapable of accurately measuring theload that is applied perpendicular to load plate and placed in aposition
12、to minimize the mass between the load cell and thepavement. The load cell shall be positioned in such a way thatit does not restrict the ability to obtain deflection measurementsunder the center of the load plate. The load cell shall be waterresistant, and shall be resistant to mechanical shocks fro
13、m roadimpacts during testing or traveling.3.1.5 load plate, nCapable of an even distribution of theload over the pavement surface. load plates may be circular inshape (or rectangular in some cases), one piece or segmented,for measurements on conventional roads and airfields orsimilar stiff pavements
14、. The plate shall be suitably constructedto allow pavement surface deflection measurements at thecenter of the plate.1This guide is under the jurisdiction of Committee E17 on Vehicle - PavementSystems and is the direct responsibility of Subcommittee E17.41 on PavementTesting, Evaluation, and Managem
15、ent Methods.Current edition approved June 1, 2008. Published July 2008. Originally approvedin 1987. Last previous edition approved in 2003 as D 4695 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMSta
16、ndards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,http:/www.transportation.org.1Copyright ASTM International, 1
17、00 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6 load transfer test, nA test, usually on PCC pave-ment, with deflection sensors on both sides of a break or jointin the pavement. The test is used to determine the ability of thepavement to transfer load from one
18、 side of the break to theother. Also, the load-deflection data can be used to predict theexistence of voids under the pavement.3.1.7 test location, nThe point at which the center of theapplied load or loads are located.4. Summary of Guide and Limitations4.1 This guide consists of standards for measu
19、ring pave-ment surface deflections directly under and/or at appropriateoffset locations from the load center. Each nondestructivetesting (NDT) device is operated according to the standardoperating procedure applicable to the device.4.2 This guide includes general descriptions of the varioustypes of
20、static and semicontinuous deflection testing devices,and procedures for deflection measurement corresponding toeach testing device.4.3 The collection of general information described in thisguide, such as test setup, ambient temperature, pavementtemperature, equipment calibration, number of tests, a
21、nd testlocations, pertain to all devices.5. Significance and Use5.1 NDT measurement of pavement surface deflectionsprovides information that can be used for the structuralevaluation of new or in-service pavements. These deflectionmeasurements may be used to determine the following pave-ment characte
22、ristics:5.1.1 Modulus of each layer.5.1.2 Overall stiffness of the pavement system.5.1.3 Load transfer efficiency of PCC pavement joints.5.1.4 Modulus of subgrade reaction.5.1.5 Effective thickness, structural number, or soil supportvalue.5.1.6 Bearing capacity or load carrying capacity of a pave-me
23、nt.5.2 These parameters may be used for the analysis anddesign of reconstructed and rehabilitated flexible and rigidpavements, pavement structural adequacy assessment includ-ing joint efficiency of PCC pavement, void detection in PCCpavement, research and/or network structural inventory pur-poses.6.
24、 Apparatus6.1 The apparatus used in this Guide shall be one of thedeflection measuring devices described in subsection 6.2 andshall consist of some type of probe or surface contact sensor(s)to measure vertical pavement movements or deformationswhen subjected to a given load.6.2 Deflection Measuring
25、Devices:6.2.1 Noncontinuous Static Device,4that operates on asingle lever-arm principle. This device shall have a minimum2.5 m (8.2 ft.) long probe, and the extension of the probe shalldepress a dial gage or electronic sensor that measures maxi-mum pavement surface deflection with a resolution of 0.
26、025mm (0.001 in.) or better. The vehicle used to impart the wheelload to the pavement shall be a truck capable of carrying aminimum 80 kN (18,000 lbf) test load on a single rear axle.The loading configuration, including axle loads, tire sizes, andinflation pressures, can be obtained using the manufa
27、cturersspecification; however, this information must be clearly indi-cated in the engineering report.6.2.2 Semicontinuous Static Device,5that operates on adouble lever-arm principle. The vehicle used to carry thisdevice shall be a truck carrying a 130 kN (29,000 lbf) singleaxle test load. The loadin
28、g configuration including axle loads,tire sizes, and inflation pressures can be obtained using themanufacturers specification; however, this information mustbe clearly indicated in the engineering report. The test vehicleshall be equipped with a double lever arm with probes, thegeometry and size of
29、which makes it possible to measure themaximum pavement surface deflection in both wheel pathswith a resolution of 0.025 mm (0.001 in.) or better. Theextension of each lever arm holding the probe shall depress anelectronic sensor, which may be of any type provided thesensor delivers an analog or digi
30、tal signal. The digital signalshall be correlated with the movement of this extension and,therefore, with the deflection of the pavement surface under theeffect of the moving test load. The truck shall be able to lift andmove the probes from one measurement point to the next,lower them onto the pave
31、ment surface, and make another set ofmeasurements in a fully automated process at a constantvehicle speed.6.2.3 Steady State Dynamic Device,6that uses a dynamicforce generator to produce a dynamic load. The force generatormay use, for example, a counter rotating mass or a servo-controlled hydraulic
32、actuator to produce the dynamic load. Thedevice that uses a counter rotating mass operates at a fixedfrequency to produce a dynamic load under a static weightapplied through a pair of rigid steel wheels. Both loadingfrequency and the magnitude of the dynamic loads may bevaried by the operator of the
33、 devices that use a servo-controlledhydraulic actuator. Depending on the model, normal operatingfrequencies range from 8 to 60 Hz and maximum dynamicforces range from 2.2 to 35.5 kN (500 to 8000 lbf) appliedthrough a single circular or dual rectangular plate, or dual steelwheels such as those used o
34、n the standard Dynaflect device. Asteady-state loading device may be mounted in a van, on thefront of a vehicle, or on a trailer. Deflection measurementdevices should have five or more sensors to satisfactorilymeasure the deflection basin with a resolution of 0.002 mm(0.0001 in.) or better.6.2.4 Imp
35、ulse Device,7that creates an impulse load on thepavement by dropping a mass from a variable height onto arubber or spring buffer system. Generically known as a FallingWeight Deflectometer (FWD), the force generating device shallbe capable of being raised to one or more predetermined4An example of th
36、is instrument is the Soiltest Benkelman Beam.5An example of this instrument is the Lacroix Decflectograph.6Examples of this instrument are the Geolog Dynaflect and the FoundationMechanics Road Rater.7Examples of this instrument are the Dynatest Falling Weight Deflectometer(FWD), the KUAB 2m-FWD, the
37、 Carl Bro FWD, and the Jils FWD.D 4695 03 (2008)2heights and dropped. The resulting force, transmitted to thepavement through a circular load plate, shall not vary betweenrepetitive drops by more than 6 3%. The force pulse shallapproximate the shape of a haversine or half-sine wave and apeak force i
38、n the range of 7 to 105 kN (1,500 to 24,000 lbf)shall be achievable. The impulse loading device shall measurepavement surface deflections using seven or more sensors witha resolution of 0.002 mm (0.0001 in.) or better.7. Calibration of Deflection Measuring Devices7.1 The deflection sensor(s) and loa
39、d cell (if applicable) ofthe deflection device should be calibrated to ensure that allreadings are accurate within specified limits. For devices wherethe load is assumed to be constant and is not measured, theaccuracy of the magnitude of load imparted should be checkedperiodically using the manufact
40、urers recommended calibra-tion procedure.7.2 Load Cell:7.2.1 GeneralThe procedure for calibrating the load cell(if the device uses a load cell) is dependent upon the type ofdevice used. The calibration of load cell may be checkedinformally by observing the load cell readings and comparingthem agains
41、t expected readings based on experience or shuntcalibration values in the case of Falling Weight Deflectometeror the Road Rater. Load cell reference (or absolute) calibrationshall be performed at least once a year except the noncontinu-ous and semicontinuous loading devices (see Table 1).7.2.2 Nonco
42、ntinuous and Semicontinuous Static LoadingDevicesImmediately prior to testing, weigh the axle load ofthe truck if the ballast consists of a material that can absorbmoisture (sand or gravel, and so forth) or could have changedfor any reason. Trucks with steel or concrete block loads onlyneed to be we
43、ighed if the loads are changed or could haveshifted.7.2.3 Impulse Loading DeviceReference load cell calibra-tion should be carried out at least once per year. Appendix A ofSHRP Report SHRP-P-661 contains an example outline forsuch a task.7.3 Deflection Sensors:7.3.1 GeneralThe procedure for calibrat
44、ing the deflectionsensors is dependent upon the type of apparatus used. Calibra-tion of the deflection sensors should be checked at least once amonth during production testing except noncontinuous andsemicontinuous loading devices (see Table 2).7.3.2 Noncontinuous and Semicontinuous Static LoadingDe
45、vicesStatic loading devices should be calibrated dailywith feeler gages. When performing deflection sensor calibra-tion, induced deflections should be similar in magnitude to thedeflections encountered during normal testing.7.3.3 Steady-State Loading DevicesA routine calibrationcheck of the deflecti
46、on sensors shall be conducted once amonth. If significant differences are noted for a sensor, it shallbe returned to the manufacturer for check or calibration understandard calibration oscillatory vibrations. Deflection sensorsshall be calibrated annually.7.3.4 Impulse Loading DevicesReference defle
47、ction sen-sor calibration should be carried out in accordance with theSHRP Protocol (see Appendix A of SHRP Report SHRP-P-661for impulse loading devices). A relative calibration checkshould be conducted once a month using the SHRP Protocol(see Appendix A of SHRP Report SHRP-P-661).7.4 Temperature Se
48、nsors:Pavement temperature sensor calibration should be carriedout using a calibrated reference thermometer and two referencesurfaces such as a “cool” and “hot” surface. Air temperaturesensor (if equipped) calibration should be carried out using tworeference temperatures, for example, carefully moni
49、tored icewater (0C) and hot water (60C). Calibration of temperaturesensors should be carried out at least once a year.8. Field Data Collection and Testing Procedures8.1 GeneralThe procedure to be followed is, to someextent, dependent upon which type of device is used. Thefollowing general information is suggested as the minimumdata that needs to be collected, regardless of the type of deviceused.8.1.1 LoadFor impulse loading devices, record the peakload applied to the pavement surface by the deflection device.For steady-state loading devices, record the peak
