1、Designation: D4695 03 (Reapproved 2015)Standard Guide forGeneral Pavement Deflection Measurements1This standard is issued under the fixed designation D4695; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 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 outw
3、ard (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 general
4、 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 r
5、einforced, 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,operations, and equipment. This standard does not purport toaddres
6、s 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:2D4602 Guide for N
7、ondestructive Testing of Pavements Us-ing Cyclic-Loading Dynamic Deflection EquipmentD4694 Test Method for Deflections with a Falling-Weight-Type Impulse Load DeviceD5858 Guide for Calculating In Situ Equivalent ElasticModuli of Pavement Materials Using Layered ElasticTheory2.2 AASHTO Standard:3T256
8、Standard 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 specified loa
9、d 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 of t
10、he 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 manner a
11、s 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 the loadthat is applied perpendicular to load plate and placed in aposition to mi
12、nimize 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 from roa
13、dimpacts 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. The
14、 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 and Evaluation.Current editio
15、n approved May 1, 2015. Published August 2015. Originallyapproved in 1987. Last previous edition approved in 2008 as D4695 03 (2008).DOI: 10.1520/D4695-03R15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of A
16、STMStandards 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.Copyright ASTM Internation
17、al, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.1.6 load transfer test, nA test, usually on PCCpavement, with deflection sensors on both sides of a break orjoint in the pavement. The test is used to determine the abilityof the pavement to transfer load from
18、one side of the break tothe other. Also, the load-deflection data can be used to predictthe existence 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 me
19、asuring 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
20、of 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
21、, and 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 chara
22、cteristics: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
23、-ment.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
24、.6. 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 Measuri
25、ng Devices:6.2.1 Noncontinuous Static Device,4that operates on a singlelever-arm principle. This device shall have a minimum 2.5 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
26、 0.025mm (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 man
27、ufacturersspecification; 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 loa
28、ding 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
29、of 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 d
30、igital 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 p
31、avement 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 hydraul
32、ic 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
33、the 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 use
34、d on 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
35、Impulse 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 Falling4An example of this instrument is the Soiltest Benkelman Beam.5An example of this instrument is the Lacroix Decflectograph.6Exampl
36、es 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.D4695 03 (2015)2Weight Deflectometer (FWD), the force generating device shallbe c
37、apable of being raised to one or more predeterminedheights 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
38、 in 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 l
39、oad 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 manufa
40、cturers 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 agai
41、nst 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 Non
42、continuous 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
43、weighed 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 calibr
44、ating 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 Loading
45、DevicesStatic loading devices should be calibrated daily withfeeler gages. When performing deflection sensor calibration,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 sensorcalibration should be carried out using a calibrated referencethermometer and two reference surfaces such as a “cool” and“hot” surface. Air temperature sensor (if equipped) calibrationshould be carried out using two reference temperatures, forexample, carefully moni
49、tored ice water (0C) and hot water(60C). Calibration of temperature sensors should be carriedout 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
