1、Designation: D 4695 03Standard 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 revision. A number in par
2、entheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 outward (offset) fr
3、om 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 general information th
4、at 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 reinforced, orco
5、ntinuously 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 toaddress all of the
6、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 for Nondestructiv
7、e 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:3T256Standard Met
8、hod 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 specified load as depicte
9、d 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 of the deflectio
10、n 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 manner as to minimiz
11、e 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 to minimize the m
12、ass 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 from roadimpacts dur
13、ing 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. The plate shall
14、 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 PavementManagement.Current edition approved Dec. 1, 2003. P
15、ublished January 2004. Originallyapproved in 1987. Last previous edition approved in 1996 as D 4695 96.2For 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 standards
16、 Document Summary page onthe ASTM website.3Available from the American Association of State Highway and TransportationOfficials, 444 N. Capitol St., NW, Washington, DC 20001.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6 load
17、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 side of the break to theother. Also, the load-deflection data can be used to predict theexist
18、ence 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 measuring pave-ment surface deflections directly under and/or at appropriateoffset locations from t
19、he 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 static and semicontinuous deflection testing devices,and procedures for deflection measurement
20、 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, and testlocations, pertain to all devices.5. Significance and Use5.1 NDT measurement of pavemen
21、t 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 characteristics:5.1.1 Modulus of each layer.5.1.2 Overall stiffness of the pavement system.5.1.3 Load
22、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-ment.5.2 These parameters may be used for the analysis anddesign of reconstructed and rehabilita
23、ted 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. Apparatus6.1 The apparatus used in this Guide shall be one of thedeflection measuring devices
24、 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 Devices:6.2.1 Noncontinuous Static Device,4that operates on asingle lever-arm principle. This
25、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 0.025mm (0.001 in.) or better. The vehicle used to impart the wheelload to the pavement shall be
26、 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 manufacturersspecification; however, this information must be clearly indi-cated in the engineering
27、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 loading configuration including axle loads,tire sizes, and inflation pressures can be obtained using
28、 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 which makes it possible to measure themaximum pavement surface deflection in both wheel pathsw
29、ith 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 digital signal. The digital signalshall be correlated with the movement of this extension and,ther
30、efore, 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 pavement surface, and make another set ofmeasurements in a fully automated process at a constantve
31、hicle 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 actuator to produce the dynamic load. Thedevice that uses a counter rotating mass operates at
32、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 devices that use a servo-controlledhydraulic actuator. Depending on the model, normal operati
33、ngfrequencies 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 on the standard Dynaflect device. Asteady-state loading device may be mounted in a van, on thef
34、ront 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 Impulse Device,7that creates an impulse load on thepavement by dropping a mass from a variable he
35、ight 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 this instrument is the Soiltest Benkelman Beam.5An example of this instrument is the Lacroix Dec
36、flectograph.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 Carl Bro FWD, and the Jils FWD.D4695032heights and dropped. The resulting force, transmitted
37、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 in the range of 7 to 105 kN (1,500 to 24,000 lbf)shall be achievable. The impulse loading device shall m
38、easurepavement 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 load cell (if applicable) ofthe deflection device should be calibrated to ensure that allreadings are accu
39、rate 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 manufacturers recommended calibra-tion procedure.7.2 Load Cell:7.2.1 GeneralThe procedure for calibrating the l
40、oad 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 against expected readings based on experience or shuntcalibration values in the case of Falling Weight Deflec
41、tometeror 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 Noncontinuous and Semicontinuous Static LoadingDevicesImmediately prior to testing, weigh the axle load ofth
42、e 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 weighed if the loads are changed or could haveshifted.7.2.3 Impulse Loading DeviceReference load cell cal
43、ibra-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 calibrating the deflectionsensors is dependent upon the type of apparatus used. Calibra-tion of the deflection
44、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 LoadingDevicesStatic loading devices should be calibrated dailywith feeler gages. When performing deflection sen
45、sor 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 deflection sensors shall be conducted once amonth. If significant differences are noted for a sensor, it shallb
46、e returned to the manufacturer for check or calibration understandard calibration oscillatory vibrations. Deflection sensorsshall be calibrated annually.7.3.4 Impulse Loading DevicesReference deflection sen-sor calibration should be carried out in accordance with theSHRP Protocol (see Appendix A of
47、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 Sensors:Pavement temperature sensor calibration should be carriedout using a calibrated reference thermom
48、eter 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 monitored icewater (0C) and hot water (60C). Calibration of temperaturesensors should be carried out at lea
49、st 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-to-peak loadand load configuration. For static loading devices, record theaxle load, tire pressure, type
