1、Designation: E 1911 09Standard Test Method forMeasuring Paved Surface Frictional Properties Using theDynamic Friction Tester1This standard is issued under the fixed designation E 1911; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision
2、, 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. Scope1.1 This test method covers the procedure for measuringpaved surface frictional properties as a function of
3、speed usingthe Dynamic Friction Tester (DF-Tester).1.2 The DF Tester consists of a horizontal spinning diskfitted with three spring loaded rubber sliders which contact thepaved surface as the disk rotational speed decreases due to thefriction generated between the sliders and the paved surface. Awat
4、er supply unit delivers water to the paved surface beingtested. The torque generated by the slider forces measuredduring the spin down is then used to calculate the friction as afunction of speed.1.3 The DF Tester can be used for laboratory investigationsand in the field on actual paved surfaces.1.4
5、 The values stated in SI (metric) units are to be regardedas standard. The inch-pound equivalents are rationalized, ratherthan exact mathematical conversions.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user
6、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:2E 274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale TireE 501 Specification for Rib Tire for
7、 Pavement Skid-Resistance TestsE 867 Terminology Relating to Vehicle-Pavement SystemsE 1845 Practice for Calculating Pavement MacrotextureMean Profile Depth3. Terminology3.1 Definitions:For Definitions of terms pertaining to this standard, seeTerminology E 867.4. Summary of Test Method4.1 This test
8、method uses a disk that spins with its planeparallel to the test surface. Three rubber sliders are mounted onthe lower surface of the disk. The disk work pavement isbrought to the desired rotational velocity, corresponding to themaximum tangential velocity of the sliders. The DF Tester iscapable of
9、providing a maximum tangential velocity of 90km/h (55 mph).4.2 Water is introduced in front of the sliders and the disk islowered to contact the test surface so that it bears the fullvelocity of the disk and model assembly.4.3 The torque is monitored continuously as the disk rota-tional velocity red
10、uces due to the friction between the slidersand the test surface.4.4 The torque signal is reduced to a measurement offriction by converting the torque to the force on the sliders anddividing by the weight of the disk and motor assembly.4.5 The friction at 20, 40, 60, and 80 km/h (12, 24, 36, and48 m
11、ph) is recorded and the friction-speed relationship may beplotted.5. Significance and Use5.1 This test method provides a measure of surface frictionas a function of sliding speed, either in the field or in alaboratory.5.2 This test method may be used to determine the relativeeffects of various polis
12、hing techniques on materials or materialcombinations.5.3 The values measured in accordance with this method donot necessarily agree or directly correlate with those obtainedutilizing other methods of determining friction properties orskid resistance.6. Apparatus6.1 DF Tester (see Fig. 1)The measurin
13、g instrumentconsists of a main body and a control unit. A portable personalcomputer or an X-Y plotter can be used to record the data. Fig.1 shows the DF Tester measuring unit, consisting of a fly wheeland disc which is driven by a motor. Three rubber sliders areattached to the disc by leaf springs.
14、The sliders are pressed on1This test method is under the jurisdiction of Committee E17 on Vehicle -Pavement Systems and is the direct responsibility of Subcommittee E17.21 on FieldMethods for Measuring Tire Pavement Friction.Current edition approved Jan. 1, 2009. Published January 2009. Originallyap
15、proved in 1998. Last previous edition approved in 2007 as E 1911 07.2For 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 Document Summary page onthe ASTM w
16、ebsite.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.the test surface by the weight of the device through threerollers. Each slider is loaded to 11.8 N (2.65 lbf) by the leafsprings. The disc and the fly wheel are connected by a sp
17、ringbalance mounted along a circle on which the rubber sliders arefixed. Due to the forces on the rubber sliders, displacementoccurs in a spring balance. This displacement is converted to anelectrical signal through a displacement transducer with anaccuracy of 61 % of full scale attached to the oppo
18、site side ofthe disc. This signal is output through a slip ring and brush,both of which are mounted on a driving shaft. The speed ofrubber sliders is measured from the output of a rotational speeddynamo.6.2 Water Supply (see Fig. 2)A water supply unit isprovided to maintain a wet condition of the te
19、st surface. Whenthe tank is 0.6 m above the tester a water flow of 3.6 l/min(0.95 gal/min) is maintained. If the flow is initiated when therotation corresponds to a tangential velocity of 85 km/h (50mph) the water thickness will be 1 mm (0.04 in.) by the timethat the velocity reaches 90 km/h (55 mph
20、) and the measure-ment is initiated.6.3 Slider (see Fig. 3)The slider assembly shall consist ofa steel backing plate to which is bondeda6by16by20mm(0.25 by 0.63 by 0.79 in.) rubber shaped as shown in Fig. 3.This shape provides a contact pressure of 150 kPa (21.5(lbf/in.2). The rubber compound shall
21、be synthetic rubber asspecified in Specification E 501 and shall have a shore hard-ness of 58 6 2. The sliders shall be replaced due to waves aftertwelve runs. The slider production date is given on the plasticbag in which they are shipped. The sliders must be used withintwelve months of the product
22、ion date to avoid effects ofpassive deterioration.NOTE 1On extremely harsh surfaces it may be necessary to replacethe sliders more often.FIG. 1 The DF Testers (Dimensions in. mm: 25.4 mm=1in.)E1911092FIG. 2 The Watering ApparatusFIG. 3 The Rubber Slider (Dimensions in mm: 25.4 mm=1in.)E19110936.4 Da
23、ta CollectionThe instantaneous value of the fric-tion is detected as a signal from the force transducer. Thevibration during measurement is absorbed by a damper. Thesignal is filtered by a first order R-C filter with a time constantof 0.1 s. The signal may be saved for future analysis.6.5 Data Recor
24、dingThe tester can be connected to apersonal computer and the data can be displayed on the screenand stored on floppy discs. As an alternative, the friction signaland the speed signal from the rotational speed dynamo can berecorded using an X-Y plotter to provide a paper record of therelation betwee
25、n friction and speed.NOTE 2Calibration of the DFTester is rarely necessary. Most unitshave operated successfully for many years without the need for calibra-tion. In the event that it is felt that a DFTester should be calibrated itshould be performed at a facility approved by the manufacturer. A lis
26、t ofcalibration and repair facilities can be obtained from the manufacturer.7. Test Samples7.1 FieldField test surfaces shall be free of loose particlesand flushed with clean water. The test surface does not have tobe horizontal provided the instrument can be leveled inworking position.7.2 Laborator
27、yLaboratory test panels shall be clean andfree of loose particles and shall be held rigidly so as not to bemoved by the forces during measurement.7.2.1 Flat laboratory test panels shall have a test surface ofat least 600 by 600 mm (24 by 24 in.) with no disturbance fromedge effects for a diameter of
28、 500 mm (20 in.).8. Procedure8.1 Place the DF Tester on the test sample that should belevel and free of any contamination.NOTE 3It is preferable to operate the DF Tester at a location where thesurface is flat. However, the effect of slope on the results is due to thedecrease of the vertical load on
29、the sliders by the cosine of the slope angle.Therefore a slope of 20 % will decrease the vertical load by only 2 %.Slopes higher than 30 % are not recommended.8.2 Start the rotation of the disk. Verify that the fly wheeland disc with three rubber sliders rotates without contacting thetest surface, a
30、nd start the water supply.8.3 When the rotating speed reaches a target speed, waterflow is closed and the driving device is lowered to the testsurface.8.4 The measurement begins, the speed of the drivingdevice gradually decreases due to the friction between rubbersliders and the test surface, and fi
31、nally stops.8.5 Record the test results or store the data for futureanalysis.9. Report9.1 Report the following information:9.1.1 Date and time of day,9.1.2 Individual values of the friction DFT Numbers forspeeds of 20, 40, 60, and 80 km/h (12, 24, 36, and 48 mph),9.1.3 Temperature of the test surfac
32、e,9.1.4 Type, age, condition, and location of test surface,9.1.5 Shore hardness and production date of the rubbersliders,9.1.6 Plot of the friction-speed curve, and9.1.7 Type and date of the most recent calibration.10. Precision and Bias10.1 PrecisionThe standard deviation of eight measure-ments on
33、the same test surface ranged from 0.044 at 30 km/hto 0.038 at 60 km/h.310.2 BiasThere is no basis for determination of the bias.NOTE 4Results from the International PIARC Experiment to Com-pare and Harmonize Texture and Skid Resistance Measurements4indi-cated a correlation with the Skid Numbers from
34、 Test Method E 274produced a correlation coefficient (R) of 0.86. The results also showedthat, when used with a measure of Mean Profile Depth, the InternationalFriction Index can be determined by the DF Tester within 60.027.11. Keywords11.1 friction; pavements; skid resistance3Saito, K., Horiguchi,
35、T, Kasahara, A., Abe, H., and Henry, J.J., Development ofa Portable Tester for Measuring Skid Resistance and its Speed Dependency onPavement Surfaces, Transportation Research Record 1536, Washington, DC 1996,pp. 45-51.4Wambold, J. C., Antle, C.E., Henry, J. J., and Rado, Z, International PIARCExperi
36、ment to Compare and Harmonize Texture and Skid Resistance Measure-ments, Final Report, Permanent International Association of Road Congresses(PIARC), Paris 1995.E1911094ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin
37、this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must
38、 be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of ther
39、esponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).E1911095
