1、Designation: E670 09 (Reapproved 2015)Standard Test Method forTesting Side Force Friction on Paved Surfaces Using theMu-Meter1This standard is issued under the fixed designation E670; 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 measurement of the sideforce friction of paved surfaces utilizing a device co
3、mmonlycalled a Mu-Meter.21.2 This test method utilizes a measurement obtained bypulling the Mu-Meter, containing two freely rotating testwheels angled to the direction of motion, over a pavementsurface at a constant speed while the test wheels are under aconstant static load. This method provides da
4、ta of the side forcefriction (and other data) along the whole length of the testsurface being tested which is applied to a variety of comput-erized algorithms enabling the production of results including(but not limited to) rolling averages, numeric and graphicalrepresentations, friction mapping and
5、 reports formatted in thelayout approved by a wide variety of national airport regula-tors.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered sta
6、ndard.1.4 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. See also
7、 Section 6.2. Referenced Documents2.1 ASTM Standards:3D297 Test Methods for Rubber ProductsChemical Analy-sisD412 Test Methods for Vulcanized Rubber and Thermoplas-tic ElastomersTensionD1054 Test Method for Rubber PropertyResilience Usinga Goodyear-Healey Rebound Pendulum (Withdrawn2010)4D1765 Class
8、ification System for Carbon Blacks Used inRubber ProductsD2240 Test Method for Rubber PropertyDurometer Hard-nessD3182 Practice for RubberMaterials, Equipment, and Pro-cedures for Mixing Standard Compounds and PreparingStandard Vulcanized SheetsE178 Practice for Dealing With Outlying ObservationsE30
9、3 Test Method for Measuring Surface Frictional Proper-ties Using the British Pendulum TesterE1551 Specification for Special Purpose, SmoothTreadTire, Operated on Fixed Braking Slip Continuous FrictionMeasuring Equipment3. Summary of Test Method3.1 The Mu-Meter consists of a trailer similar to the on
10、e inFig. 1, which is towed by a vehicle.23.2 The test tires are positioned in the test mode. TheMu-Meter is brought to the desired test speed. Water (ifapplicable) is delivered ahead of the test tires and the beginningof the test is marked. The resulting sideways friction forceacting between the tes
11、t tires and the pavement surface isdigitized and recorded in the volatile memory of the processor1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle- Pavement Systems and is the direct responsibility of Subcommittee E17.21 onField Methods for Measuring Tire Pavement Friction
12、.Current edition approved June 15, 2015. Published August 2015. Originallyapproved in 1985. Last previous edition approved in 2009 as E670 09. DOI:10.1520/E0670-09R15.2The sole source of supply of the apparatus known to the committee at this timeis Douglas Equipment Ltd, Douglas House, Village Road,
13、 Arle, Cheltenham,Gloucestershire UK GL51 0AB and Douglas Equipment International, 8305Cherokee Boulevard, Douglasville, Douglas County, Atlanta, Georgia 30134 USA.If you are aware of alternative suppliers, please provide this information to ASTMInternational Headquarters. Your comments will receive
14、 careful consideration at ameeting of the responsible technical committee,1which you may attend.3For 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 Docume
15、nt Summary page onthe ASTM website.4The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1mounted on the trailer and subsequently displayed on thein-cab moni
16、tor (usually a laptop or tablet computer) forsubsequent display or downloading. The speed and distancetraveled by the test vehicle is also recorded by integratedon-board systems.FIG. 1 Mu-Meter SchematicsE670 09 (2015)23.3 The friction analysis is displayed on the in cab monitorand can be down loade
17、d to other PCs as required by the clientfor analysis utilising the software provided. Results report theMu Number (MuN).54. Significance and Use4.1 The knowledge of side force friction serves as anadditional tool in characterizing pavement surfaces. Side forcefriction data alone may be of limited va
18、lue in determining thesuitability of paving materials or finishing techniques.However, when used in conjunction with other physical andchemical tests, the side force friction may contribute tocharacterization of pavement surfaces.4.2 The values measured with the equipment and proce-dures stated here
19、in do not necessarily agree or correlatedirectly with those obtained by other paved surface frictionmeasuring methods.5. Apparatus5.1 Tow VehicleThe tow vehicle shall be capable oftowing the Mu-Meter at a speed of at least 40 mph (65 km/h)and maintaining this speed within 60.5 mph (0.8 km/h). Iftest
20、s are conducted at speeds greater than 40 mph, the vehicleshall be capable of maintaining these speeds within 61 mph(1.5 km/h). The vehicle shall have a suitable towing hitch ofeither ring eye or ball hitch design. The towing ball/hook shallbe placed so that the standard datum line on the Mu-Meter i
21、s12 6 0.5 in. (305 6 13 mm) from the ground. In either case thehitch height shall not vary more than 2 in. (51 mm) between theloaded and unloaded towing vehicle condition.5.2 General Requirements for Measuring SystemThe in-strumentation system shall conform to the following overallrequirements at am
22、bient temperatures between 40 and 100F (4and 38C) as follows:-Overall system accuracy 3 % of full scale-Time stability calibration 10 h minimum-The exposed portions of the measuring system shall tolerate 100 %relative humidity (rain or spray) and all other adverse conditions,such as dust, shock, and
23、 vibrations that may be encountered inpavement test operations.5.2.1 TrailerThe trailer configuration for testing shall beessentially as shown in Fig. 1 with the two test wheels, eachmounted so that when the measuring position is selected thefront of each wheel shall be splayed out to angle of 7.50
24、60.75 (15.00 inclusive angle) relative to the centerline of theMu-Meter. The two test wheels are mounted on frames joinedat the towbar on a needle bearing which allows them to pivotrelative to each other, such travel limited by sensitive straingauge, which senses the side force friction, generated b
25、etweenthe wheels. The rear-centralized wheel operates a distanceencoder, which is utilized by the system to measure distancetraveled and via an internal clock speed.5.2.2 Force CellThe geometry of the chassis structurewithin the measuring A frame fabrication ensures that the loadcell is mounted in a
26、 position such that 500 lbf (2225 N) oftensile force is equivalent to the side force exerted by thewheels on a pavement having a MuN (Mu Number) of 100.The extension of the load cell during a test shall be sufficientlysmall to limit the movement of the measuring wheels in sucha way that the total in
27、cluded angle between the test tires doesnot change by more than 0.5 during the test. The load cellshall provide an output directly proportional to the force withhysteresis less than 2 % of the applied load up to the maximumexpected loading, and sensitivity to any expected cross-axisloading less than
28、 2 % of the applied load. The load cell shall bemounted in such a manner as to experience less than 1 angularrotation from the horizontal plane at the maximum expectedloading.5.2.3 Wheel LoadThe apparatus shall have the followingvertical static loads when the unit is in the toe-out positionready for
29、 testing and when the tires are inflated to their properpressures:Each test wheel 1712lbf(7619N)Rear wheel 118 to 138 lbf (525 to 614 N)Towing hitch 80 lbf (360 N)5.2.4 Tires (see Annex A1 Annex A3):5.2.4.1 The Mu-Meter will be fitted with tires manufacturedto Specification E1551. The tire pressure
30、in the two test wheelsshall be 10 6 0.5 psi (69 6 3 kPa) measured at ambienttemperature (cold).5.2.4.2 The rear-stabilizing tire shall be treaded and shall bethe same size as the test tires. Tire pressure in the rear-stabilizing tire shall be 30 6 2 psi (207 6 14 kPa) measured atambient temperature
31、(cold).5.2.5 Processor CPUThe CPU shall record and interpretthe data output of the load cell over the range 0 to 500 lbf (0to 2225 N) and store the processed data within its volatilememory and on the cab laptop nominated drive. The CPU shallalso store unlimited event markers (dependant on displaydef
32、inition and pixilation) The CPU will also store and processthe start and end position of each run, the time of start andother information inputted manually by the operator for runreferencing at a later date.5.2.6 Vehicle Speed-Measuring EncoderThe distance andspeed encoders shall provide speed resol
33、ution and accuracy of61.5 % of the indicated speed or 60.5 mph (60.8 km/h),whichever is greater. The output shall be directly viewable bythe operator. The speed shall be recorded.5.3 Pavement Wetting System:5.3.1 The water shall be applied to the pavement ahead ofthe test tires utilising a nozzle ma
34、nufactured to the dimensionsconforming to Fig. 2. For airport runways, the recommendedquantity of water applied shall be proportional to test speed andto provide a depth of 0.020 in. (0.5 mm) over a width at least1 in. (25 mm) wider than the toed-out test-tire pavement widthand applied so the tire i
35、s centrally located between the wettededges during the actual testing.5.3.2 The nozzle configuration and position, shall ensurethat the nozzle centerline is pointed toward the paved surfaceat an angle of 25 6 2. The water shall strike the paved surface6 to 8 in. (150 to 200 mm) ahead of the vertical
36、 centerline ofthe Mu-Meter test tire. The nozzle shall be of such a height thatit clears all obstacles that the Mu-Meter is expected to5Refer to manufacturers operational manual (SEDP316 Iss.10) for method ofinterpreting Mu numbers from the data.E670 09 (2015)3FIG. 2 Pavement WettingE670 09 (2015)4e
37、ncounter and shall provide a water-wetted width as required in5.3.1, but in no case shall the nozzle be more than 4 in. (100mm) above the paved surface.5.3.3 The water used shall be reasonably clean with nochemicals added, such as wetting agents or detergents.6. Safety Precautions6.1 The towing vehi
38、cle and Mu-Meter, as well as allattachments, shall comply with all applicable state and federallaws. All necessary precautions shall be taken to ensure thesafety of personnel and other traffic. No tests shall be made ifthere is danger that the dispersed water may freeze on thepavement.7. Sampling7.1
39、 Test SectionsSharp curves and steep grades shall notbe included in a test section with level tangent sections, norshall passing lanes be included with traffic lanes. An attemptshall be made to keep test sections as uniform as possible so theresulting average of the recorded test shall be an average
40、 of auniform surface. Normally, highway testing shall be accom-plished with the left test wheel in the center portion of the leftwheel wear path of a traffic lane. Normally, for monitoringpurposes, airport testing shall be performed approximately 10ft (3 m) from the centerline of the runway and shou
41、ldencompass the full length of the runway. Areas of the runwaywith rubber deposit buildup, paint markings, or othercontaminants, shall be analyzed as separate sections.8. Calibration8.1 All aspects of calibration of the Mu-Meter are coveredin Appendix X1 of this test method.9. General9.1 Tire Prepar
42、ationNew test wheel tires must be condi-tioned by running them at their normal inflation pressures inthe test position on the Mu-Meter, until such time as therunning surface of the tire adopts a consistent smooth mattappearance, usually 46 miles. Inspect previously used tires fordamage and other irr
43、egularities that may affect the test resultsand reject tires that have been damaged or worn to the extentthat the underlying ply stranding has become to be exposed.9.2 Test PreparationCheck the tires for flat spots,irregularities, or other damage before running a test. Check theinflation pressures i
44、n accordance with 5.2.4. Recheck thesuspension to see that it is free to move with no binding or tightspots. Prior to each series of tests, warm up the tires bytraveling at least 5 miles (8 km) at normal traffic speeds in thenormal non toed-out position. Place the test wheels in thetoe-out position
45、and the third wheel in the down position. Thetest wheels shall be free to rotate but locked in the toe-outposition. The rear wheel shall be free to move up and down,restrained only by its spring load.9.3 Test SpeedsRun the standard test at 40 6 0.5 mph (656 0.8 km/h) or in accordance with the local
46、national regula-tions. Maintain test speeds of 40 mph or less to 60.5 mph andtest speeds over 40 mph to 61.0 mph (1.5 km/h). At all speedsother than 40 mph, record the speeding the screen positionnoted.10. Procedure10.1 Check the Mu-Meter as in 9.2. Bring the apparatus tothe test speed. If required
47、by local regulations, begin deliveryof water to the test tires approximately 1 second before the testis initiated and continue until the test is completed or watersupply depleted, whichever occurs first.10.2 Mu numbers will be displayed on the in cab laptopdisplay, along with other reported data as
48、defined necessary forthe selected national standard.11. Faulty Tests11.1 Tests that are faulty or give Mu Numbers differing bymore than 5 MuN from the average of all tests of the same testsection shall be treated in accordance with Practice E178.12. Report12.1 Field ReportThe field report for each t
49、est sectionshall contain data on the following items:12.1.1 Location and identification of test section,12.1.2 Date and time of day,12.1.3 Weather conditions (principally temperature, cloudcover, and wind),12.1.4 Lane and section tested,12.1.5 Speed of test vehicle and water depth (for each test),12.1.6 Average Mu Number for each test section,12.2 Summary ReportThe summary report shall include,for each test section, data on the following items insofar as theyare pertinent to the variables or combinations of variablesunder investigation:12.2.1 Loc
