ASTM_E_1911_-_09ae1.pdf

Designation:E191109a1Standard Test Method forMeasuring Paved Surface Frictional Properties Using theDynamic Friction Tester1This standard is issued under the fixed designation E1911;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 parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTENote 2 was editorially corrected in July 2009.1.Scope1.1 This test method covers the procedure for measuringpaved surface frictional properties as a function of 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.Awater 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 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 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:2E274 Test Method for Skid Resistance of Paved SurfacesUsing a Full-Scale TireE501 Specification for Rib Tire for Pavement Skid-Resistance TestsE867 Terminology Relating to Vehicle-Pavement SystemsE1845 Practice for Calculating Pavement MacrotextureMean Profile Depth3.Terminology3.1 Definitions:For Definitions of terms pertaining to thisstandard,see Terminology E867.4.Summary of Test Method4.1 This test 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 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 reduces 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 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 polishing 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.1This 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 approvedin 1998.Last previous edition approved in 2009 as E1911 09.DOI:10.1520/E1911-09AE01.2For 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 website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Apparatus6.1 DF Tester(see Fig.1)The measuring 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.The sliders are pressed onthe 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 springbalance 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 s