1、Designation: E303 93 (Reapproved 2018)Standard Test Method forMeasuring Surface Frictional Properties Using the BritishPendulum Tester1This standard is issued under the fixed designation E303; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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.1. Scope1.1 This test method covers the procedure for measuringsurface frictional properties using the Briti
3、sh pendulum skidresistance tester.2A method for calibration of the tester isincluded in Annex A1.1.2 The British pendulum tester is a dynamic pendulumimpact-type tester used to measure the energy loss when arubber slider edge is propelled over a test surface. The tester issuited for laboratory as we
4、ll as field tests on flat surfaces, andfor polish value measurements on curved laboratory specimensfrom accelerated polishing wheel tests.1.3 The values measured, BPN = British pendulum (tester)number for flat surfaces and polish values for acceleratedpolishing wheel specimens, represent the frictio
5、nal propertiesobtained with the apparatus and the procedures stated hereinand do not necessarily agree or correlate with other slipperinessmeasuring equipment.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standar
6、d 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, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.6 This intern
7、ational standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Co
8、mmittee.2. Referenced Documents2.1 ASTM Standards:2E501 Specification for Standard Rib Tire for PavementSkid-Resistance Tests3. Summary of Test Method3.1 This test method consists of using a pendulum-typetester with a standard rubber slider to determine the frictionalproperties of a test surface.3.2
9、 The test surface is cleaned and thoroughly wetted priorto testing.3.3 The pendulum slider is positioned to barely come incontact with the test surface prior to conducting the test. Thependulum is raised to a locked position, then released, thusallowing the slider to make contact with the test surfa
10、ce.3.4 A drag pointer indicates the British pendulum (tester)number. The greater the friction between the slider and the testsurface, the more the swing is retarded, and the larger the BPNreading. Four swings of the pendulum are made for each testsurface.4. Significance and Use4.1 This test method p
11、rovides a measure of a frictionalproperty, microtexture of surfaces, either in the field or in thelaboratory.4.2 This test method may be used to determine the relativeeffects of various polishing processes on materials or materialcombinations.4.3 The values measured in accordance with this method do
12、not necessarily agree or directly correlate with those obtainedutilizing other methods of determining friction properties orskid resistance.NOTE 1BPN and polish values from similar types of surfaces will notbe numerically equal, primarily because of the differences in slide lengthand surface shape.
13、Theoretical correction of the polish values to obtainnumerical equality, either by mathematical manipulation or by use ofspecial measuring scales, is not recommended.5. Apparatus5.1 British Pendulum Tester (Fig. 1)The pendulum withslider and slider mount shall weigh 1500 6 30 g. The distance1This te
14、st method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17.23 onSurface Characteristics Related to Tire Pavement Slip Resistance.Current edition approved May 1, 2018. Published May 2018. Originallyapproved in 1961. Last
15、 previous edition approved in 2013 as E303 93 (2013).DOI: 10.1520/E0303-93R18.2For 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 on
16、the ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDev
17、elopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1of the center of gravity of the pendulum from the center ofoscillation shall be 411 6 5 mm (16.2 6 0.2 in.). The testershall be capable of vertical adju
18、stment to provide a slidercontact path of 125 6 1.6 mm (41516 6116 in.) for tests on flatsurfaces, and 76 to 78 mm (3 6116 in.) for tests on polishingwheel specimens. The spring and lever arrangement shown inFig. 2 shall give an average normal slider load between the76-mm (3-in.) wide slider and tes
19、t surface of 2500 6 100 g, asmeasured by the method prescribed in Annex A1.5.2 SliderThe slider assembly shall consist of an alumi-num backing plate to which is bondeda6by25by76-mm (14by 1 by 3-in.) rubber strip for testing flat surfaces, or a 6 by 25by 32-mm (14 by1by114-in.) rubber strip for testi
20、ng curvedpolishing wheel specimens. The rubber compound shall benatural rubber meeting the requirements of the Road ResearchLaboratory,3or synthetic rubber as specified in SpecificationE501.3Giles, C. G. Sabey, Barbara E., and Carden, K. W. F., “Development andPerformance of Portable Skid-Resistance
21、 Tester,” Road Research Technical PaperNo. 66, Road Research Laboratory, Dept. of Scientific and Industrial Research,England, 1964.Kummer, H. W. and Moore, D. F. “Concept and Use of the British PortableSkid-Resistance Tester,” Report No. 6, PDH-PSV Joint Road Friction Program,Dept. of Mechanical Eng
22、ineering, The Pennsylvania State University, State College,PA 16802, June 1963.FIG. 1 British Pendulum TesterFIG. 2 Schematic Drawing of Pendulum Showing Spring and Le-ver ArrangementE303 93 (2018)25.2.1 New sliders shall be conditioned prior to use bymaking ten swings on No. 60 grade silicon carbid
23、e cloth4orequivalent under dry conditions. The swings shall be madewith a tester adjusted as in Section 7.5.2.2 Wear on the striking edge of the slider shall not exceed3.2 mm (18 in.) in the plane of the slider or 1.6 mm (116 in.)vertical to it, as illustrated in Fig. 3.5.3 Accessories:5.3.1 Contact
24、 path gage shall consist of a thin ruler, suitablymarked for measuring contact path length between 124 and127 mm (478 and 5.0 in.) or between 75 and 78 mm (21516 and3116 in.), as required for the particular test.5.3.2 Miscellaneous equipment, such as water container,surface thermometer, and brush is
25、 recommended.6. Test Specimen6.1 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 using only the leveling screws and thependulum head will clear the surface
26、.6.2 LaboratoryLaboratory test panels shall be clean andfree of loose particles and shall be held rigidly so as not to bemoved by the force of the pendulum.6.2.1 Flat laboratory test panels shall have a test surface ofat least 89 by 152 mm (312 by 6 in.).6.2.2 Accelerated laboratory polishing wheel
27、specimensshall have a test surface of at least 44 by 89 mm (134 by 312 in.)and shall be curved in the arc of a circle 406 mm (16 in.) indiameter.7. Preparation of Apparatus7.1 LevelingLevel the instrument accurately by turningleveling screws until the bubble is centered in the spirit level.7.2 Zero
28、AdjustmentRaise pendulum mechanism by loos-ening locking knob (directly behind pendulum pivot) and turneither of pair of head movement knobs at center of tester toallow slider to swing free of test surface. Tighten locking knobfirmly. Place pendulum in release position and rotate the dragpointer cou
29、nter clockwise until it comes to rest against adjust-ment screw on pendulum arm. Release pendulum and notepointer reading. If reading is not zero, loosen locking ring androtate friction ring on bearing spindle slightly and lock again.Repeat test and adjust friction ring until the pendulum swingcarri
30、es pointer to zero.7.3 Slide Length Adjustment:7.3.1 With pendulum hanging free, place spacer underadjusting screw of lifting handle. Lower pendulum so edge ofslider just touches surface. Lock pendulum head firmly, raiselifting handle, and remove spacer.7.3.2 Raise slider by lifting handle, move pen
31、dulum to right,lower slider, and allow pendulum to move slowly to left untiledge of slider touches surface. Place gage beside slider andparallel to direction of swing to verify length of contact path.Raise slider, using lifting handle, and move pendulum to left,then slowly lower until slider edge ag
32、ain comes to rest onsurface. If the length of the contact path is not between 124 and127 mm (478 and 5.0 in.) on flat test specimens, or between 75and 78 mm (21516 and 3116 in.) on curved polishing wheelspecimens, measured from trailing edge to trailing edge of therubber slide, adjust by raising or
33、lowering instrument with thefront leveling screws. Re-adjust level of instrument if neces-sary. Place pendulum in release position and rotate the dragpointer counter-clockwise until it comes to rest against adjust-ment screw on pendulum arm.8. Procedure8.1 Apply sufficient water to cover the test ar
34、ea thoroughly.Execute one swing, but do not record reading.NOTE 2Always catch the pendulum during the early portion of itsreturn swing. While returning the pendulum to its starting position, raisethe slider with its lifting handle to prevent contact between the slider andthe test surface. Prior to e
35、ach swing, the pointer should be returned untilit rests against the adjustment screw.8.2 Without delay, make four more swings, re-wetting thetest area each time, and record the results.NOTE 3Care should be taken that the slider remains parallel to the testsurface during the swings, and does not rota
36、te so that one end rather thanthe entire striking edge makes the initial contact. Available data indicatethat tilting of the slider may cause erroneous BPN readings.Installation of a small, flat spring will relieve the problem. The springcan be inserted into a slot in the spring clip and the assembl
37、y secured bythe cotter pin as shown in Fig. 4. The free ends of the spring can rest onthe slider backing plate to restrain the slider from tilting.8.3 Recheck the slide contact length in accordance with 4.3.9. Report9.1 Report the following information:9.1.1 Individual values in BPN or polish value
38、units,9.1.2 Temperature of the test surface,9.1.3 Type, age, condition, texture, and location of testsurface,4The sole source of supply of the apparatus known to the committee at this timeis available from 3M Co., St. Paul, MN, under the trade name of Type BSafety-Walk. If you are aware of alternati
39、ve suppliers, please provide this informa-tion to ASTM International Headquarters. Your comments will receive carefulconsideration at a meeting of the responsible technical committee,1which you mayattend.FIG. 3 Slider Assembly Illustrating the Maximum Wear on Strik-ing EdgeE303 93 (2018)39.1.4 Type
40、and source of aggregate for polish value tests,and9.1.5 Type and age of the rubber slider.10. Precision and BiasNOTE 4The following material pertains only to the precision and biasof BPN units.10.1 Repeated tests show standard deviations as follows:British rubber sliders 1.0 BPN unitRubber sliders (
41、conforming toSpecification E501)1.2 BPN unitsIn both cases, the upper quartile of variability is representedin prevailing test instruments.As there is no marked correlationbetween standard deviation and arithmetic mean of sets of testvalues, it appears that standard deviations are pertinent to thist
42、est regardless of the average skid resistance being tested.10.2 The relationship, if any exists, of observed BPN unitsto some “true” value of skid resistance has not and probablycannot be studied. As a result, precision and bias of this test inrelation to a true skid resistance measure cannot be eva
43、luated,and only repeatability is given for the method.10.3 Determine the testing error as follows:E 5 tn21/2(1)where:E = testing error,t = normal curve of 1.96 or 2.0 rounded, = standard deviation of individual test results (BPN units),andn = number of tests.10.4 In order to ensure that the testing
44、error stays within 1.0BPN unit at a 95 % confidence level (corresponding to anormal curve of 1.96 or 2.0 rounded), the following samplesizes are needed:British natural rubber sliders 4Synthetic rubber sliders (conforming to Specification E501)5ANNEX(Mandatory Information)A1. CALIBRATIONA1.1 Weight o
45、f PendulumThe pendulum arm withmounted rubber slider shall be disconnected from the instru-ment and weighed to the nearest 1 g.A1.2 Center of GravityThe center of gravity of thependulum with a mounted rubber slider shall be determined byplacing the pendulum assembly over a knife edge and experi-ment
46、ally locating the point of balance as shown in Fig. A1.1.The adapter nut shall be held at the far end of the arm by a lightpaper wedge. After the point of balance has been obtained, theposition of the balance weight shall be adjusted until the slidesof the pendulum foot are horizontal.A1.3 Distance
47、of Center of Gravity from Center ofOscillationWith the pendulum reconnected to thetester and knurled bearing cap removed, distance shall beFIG. 4 Spring Clip and Spring to Inhibit Slider RotationFIG. A1.1 Pendulum Assembly Showing Location of the Point of BalanceE303 93 (2018)4measured from the cent
48、er of oscillation (center of bearing nut)to the point of balance (center of gravity). This distance shallbe measured directly to the nearest 1 mm (0.04 in.).A1.4 Slider LoadThe pendulum shall be clamped to aholder attached to the scale plate of the tester, and the testerplaced and leveled on a tripo
49、d stand as shown in Fig. A1.2.Insert the spacer. Adjust the pan balance with a bearingassembly (see Note A1.1) on one pan and tare weights on theother pan so that the balance pointer is at center scale reading.The pendulum, with a slider, shall be lowered with the verticalheight knobs of the tester until the slider is approximately0.25 mm (0.01 in.) from the top surface of the bearingassembly. Lock vertical height knob and remove the spacer.This will cause an unbalance which shall be partially compen-sated by adding weights to the opposite pan to
