1、Designation: E 670 09Standard Test Method forTesting Side Force Friction on Paved Surfaces Using theMu-Meter1This standard is issued under the fixed designation E 670; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t 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 commonlycalled a M
3、u-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 data of the side fo
4、rcefriction (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 reports formatte
5、d 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 standard.1.4 This st
6、andard 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 Section 6.2. Ref
7、erenced Documents2.1 ASTM Standards:3D 297 Test Methods for Rubber ProductsChemicalAnalysisD 412 Test Methods for Vulcanized Rubber and Thermo-plastic ElastomersTensionD 1054 Test Method for Rubber PropertyResilience Us-ing a Goodyear-Healey Rebound PendulumD 1765 Classification System for Carbon Bl
8、acks Used inRubber ProductsD 2240 Test Method for Rubber PropertyDurometerHardnessD 3182 Practice for RubberMaterials, Equipment, andProcedures for Mixing Standard Compounds and Prepar-ing Standard Vulcanized SheetsE 178 Practice for Dealing With Outlying ObservationsE 303 Test Method for Measuring
9、Surface Frictional Prop-erties Using the British Pendulum TesterE 1551 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 one inFig. 1, which is towed
10、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 test tires and the pavement su
11、rface isdigitized and recorded in the volatile memory of the processormounted on the trailer and subsequently displayed on thein-cab monitor (usually a laptop or tablet computer) forsubsequent display or downloading. The speed and distancetraveled by the test vehicle is also recorded by integratedon
12、-board systems.1This 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.Current edition approved Aug. 1, 2009. Published September 2009. Originallyapprov
13、ed in 1985. Last previous edition approved in 2000 as E 670 94 (2000),which was withdrawn in 2008 and reinstated in August 2009.2The sole source of supply of the apparatus known to the committee at this timeis Douglas Equipment Ltd, Douglas House, Village Road, Arle, Cheltenham,Gloucestershire UK GL
14、51 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 careful consideration at ameeting of t
15、he 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 Document Summary page onthe ASTM website.1Cop
16、yright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.3 The friction analysis is displayed on the in cab monitorand can be down loaded to other PCs as required by the clientfor analysis utilising the software provided. Results report theMu N
17、umber (MuN).44. 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 value in determining thesuitability of paving materials or finishing techniques. How-ever, when used in conjun
18、ction with other physical and4Refer to manufacturers operational manual (SEDP316 Iss.10) for method ofinterpreting Mu numbers from the data.FIG. 1 Mu-Meter SchematicsE670092chemical tests, the side force friction may contribute tocharacterization of pavement surfaces.4.2 The values measured with the
19、 equipment and proce-dures stated herein 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 sp
20、eed within 60.5 mph (0.8 km/h). Iftests 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
21、 standard datum line on the Mu-Meter is12 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 t
22、he following overallrequirements at ambient temperatures between 40 and 100F (4and 38C) as follows:-Overall system accuracy 63 % 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 adve
23、rse conditions,such as dust, shock, and 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
24、 shall be splayed out to angle of 7.50 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 sens
25、es the side force friction, generated betweenthe 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 en
26、sures that the loadcell is mounted in a 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 measurin
27、g wheels in sucha way that the total included 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 a
28、ny expected cross-axisloading less than 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 u
29、nit is in the toe-out positionready for testing and when the tires are inflated to their properpressures:Each test wheel 171 6 2 lbf (761 6 9N)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 manufac
30、turedto Specification E 1551.The tire pressure 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
31、 (207 6 14 kPa) measured atambient temperature (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 u
32、nlimited event markers (dependant on displaydefinition 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 dista
33、nce andspeed encoders shall provide speed resolution 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 paveme
34、nt ahead ofthe test tires utilising a nozzle manufactured 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 te
35、st-tire pavement widthand applied so the tire is 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
36、 to 8 in. (150 to 200 mm) ahead of the vertical centerline ofthe Mu-Meter test tire. The nozzle shall be of such a height thatit clears all obstacles that the Mu-Meter is expected toencounter and shall provide a water-wetted width as required in5.3.1, but in no case shall the nozzle be more than 4 i
37、n. (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 vehicle and Mu-Meter, as well as allattachments, shall comply with all applicable state and federallaws. All necessary pr
38、ecautions 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.E670093FIG. 2 Pavement WettingE6700947. Sampling7.1 Test SectionsSharp curves and steep grades shall notbe included in a test secti
39、on 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 of auniform surface. Normally, highway testing shall be accom-plished with the
40、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 shouldencompass the full length of the runway. Areas of the runwaywith rubber deposi
41、t buildup, paint markings, or other contami-nants, 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 PreparationNew test wheel tires must be condi-tioned by running them at their normal
42、 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 irregularities that may affect the test resultsand reject tires that have been da
43、maged or worn to the extentthat the underlying ply stranding has become to be exposed.9.2 Test PreparationCheck the tires for flat spots, irregu-larities, or other damage before running a test. Check theinflation pressures in accordance with 5.2.4. Recheck thesuspension to see that it is free to mov
44、e 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 and the third wheel in the down position. Thetest wheels shall be free to ro
45、tate 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 national regula-tions. Maintain test speeds of 40 mph or less to 60.5 mph an
46、dtest 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 by local regulations, begin deliveryof water to the test tires approximately
47、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 defined necessary forthe selected national standard.11. Faulty Tests11.1 Test
48、s 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 E 178.12. Report12.1 Field ReportThe field report for each test sectionshall contain data on the following items:12.1.1 Location and ide
49、ntification 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 Location and identification of test section,12.2.2 Number of lanes and presence of lane
