ASTM E1911-2009a Standard Test Method for Measuring Paved Surface Frictional Properties Using the Dynamic Friction Tester.pdf

1、Designation: E 1911 09aStandard 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 revisio

2、n, 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. Awa

4、ter 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.

5、4 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 fo

7、r 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 re

10、duces 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

11、mph) 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 poli

12、shing 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 measuri

13、ng 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 July 1, 2009. Published July 2009. Originally app

15、rovedin 1998. Last previous edition approved in 2009 as E 1911 09.2For 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 web

16、site.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 spri

17、ngbalance 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 opposi

18、te 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 test

19、 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 be

21、 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 productio

22、n 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.)E 1911 09a2FIG. 2 The Watering ApparatusFIG. 3 The Rubber Slider (Dimensions in mm: 25.4 mm=1in.)E 1911 09a36.

23、4 Data 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 R

24、ecordingThe 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 be

25、tween friction and speed.6.6 CalibrationTo determine if the DF Tester should becalibrated measure the friction of a calibration panel suppliedby the manufacturer. The calibration panel has been preparedand polished to a stable condition such that the change infriction from the previous measurement i

26、s minimal. If the valueat 40 km/h is more than 60.03 from the last measurementmade on the panel, calibration is recommended. Otherwise theunit does not need to be calibrated. It is recognized that overtime the panel will be polished by the tests performed on it, sothe criterion is based only on the

27、change from the previous testwhich shall have been recorded and stored with the panel. Caremust also be taken in storing the calibration panel so that itssurface is not damaged.NOTE 2Calibration of the DFTester is rarely necessary. Most unitshave operated successfully for many years without the need

28、 for calibra-tion. In the event that it is found that a DFTester should be calibrated itshould be performed at a facility approved by the manufacturer. A list ofcalibration and repair facilities can be obtained from the manufacturer.7. Test Samples7.1 FieldField test surfaces shall be free of loose

29、particlesand flushed with clean water. The test surface does not have tobe horizontal provided the instrument can be leveled inworking position.7.2 LaboratoryLaboratory test panels shall be clean andfree of loose particles and shall be held rigidly so as not to bemoved by the forces during measureme

30、nt.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 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 preferabl

31、e 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 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

32、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, and 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 test

33、surface.8.4 The measurement begins, the speed of the drivingdevice gradually decreases due to the friction between rubbersliders and the test surface, and finally 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

34、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 surface,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 fric

35、tion-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 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 f

36、rom the International PIARC Experiment to Com-pare and Harmonize Texture and Skid Resistance Measurements4indi-cated a correlation with the Skid Numbers from Test Method E 274produced a correlation coefficient (R) of 0.86. The results also showedthat, when used with a measure of Mean Profile Depth,

37、the InternationalFriction Index can be determined by the DF Tester within 60.027.11. Keywords11.1 friction; pavements; skid resistance3Saito, K., Horiguchi, T, Kasahara, A., Abe, H., and Henry, J.J., Development ofa Portable Tester for Measuring Skid Resistance and its Speed Dependency onPavement Su

38、rfaces, Transportation Research Record 1536, Washington, DC 1996,pp. 45-51.4Wambold, J. C., Antle, C.E., Henry, J. J., and Rado, Z, International PIARCExperiment to Compare and Harmonize Texture and Skid Resistance Measure-ments, Final Report, Permanent International Association of Road Congresses(P

39、IARC), Paris 1995.E 1911 09a4ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof inf

40、ringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this stand

41、ard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your vi

42、ews 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).E 1911 09a5