ASTM_E_2157_-_15.pdf

Designation:E215715Standard Test Method forMeasuring Pavement Macrotexture Properties Using theCircular Track Meter1This standard is issued under the fixed designation E2157;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.1.Scope1.1 This test method covers the procedure for obtaining andanalyzing pavement macrotexture profiles using the CircularTrack Meter(CTMeter).1.2 The CTMeter consists of a charge coupled device(CCD)laser displacement sensor that is mounted on an armthat rotates such that the displacement sensor follows a circulartrack having a diameter of 284 mm.1.3 The CTMeter is designed to measure the same circulartrack that is measured by the Dynamic Friction Tester(DFTester).1.4 The CTMeter can be used both for laboratory investi-gations and in the field on actual paved surfaces.1.5 The software developed for the CTMeter reports themean profile depth(MPD)and the root mean square(RMS)values of the macrotexture profiles.1.6 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.7 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:2E867 Terminology Relating to Vehicle-Pavement SystemsE1845 Practice for Calculating Pavement MacrotextureMean Profile DepthE1911 Test Method for Measuring Paved Surface FrictionalProperties Using the Dynamic Friction Tester2.2 Other Document:Manufacturers“Operating Manual for the Circular TextureMeter”33.Terminology3.1 See Terminology E867.3.2 Definitions:3.2.1 negative texture,nmacrotexture produced by de-pressions in the surface.3.2.2 positive texture,nmacrotexture produced by asperi-ties projecting above the surface.4.Summary of Test Method4.1 This test method uses a displacement sensor that ismounted on an arm that rotates clockwise at a fixed elevationfrom the surface being measured.The sensor is attached to thearm at a radius of 142 mm.The sensor measures verticalmacrotexture depth and does not account for concave recessesin the pavement surface.4.2 The device is controlled by a notebook computer thatsaves and processes the data.When the measurement isinitiated by the computer,a DC motor drives the arm for a full360 revolution.4.3 The profile is recorded in the computer memory anddivided into eight segments for analysis(See Fig.1).Thecomputer software can process the data to report either theMPD in accordance with Practice E1845 or the RMS or bothfor each segment.5.Significance and Use5.1 In the PIARC International Experiment(1)4it wasfound that the volumetric mean texture depth(MTD)washighly correlated to the speed constant of the InternationalFriction Index.It has been found that the average of the MPD1This test 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 1,2015.Published June 2015.Originallyapproved in 2001.Last previous edition approved in 2009 as E2157 09.DOI:10.1520/E2157-15.2For 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.3Available from Nippo Sangyo Co.,Ltd.,12-26,Higashi Tokura 2-Chome,Kokubunji-shi,Tokyo 185-0002,Japan.4The boldface numbers given in parentheses refer to a list of references at theend of the text.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 values for the eight segments using the CTMeter is extremelyhighly correlated with the MTD and can replace the volumetricmeasurement for determination of the MTD(2).The recom-mended relationship for the estimate of the MTD from theMPD by the CTMeter is:MTD5 0.947 MPD10.069(1)Where MTD and MPD are expressed in millimetres.NOTE1These equations differ from those given in Practice E1845,which are for the estimated texture depths from linear profiles.5.2 Comparison of the MPD and the RMS for a surfaceprovides information of the nature of the texture,that is,whether the texture is positive or negative(3).5.3 Analysis of the individual segments can be performed toexamine the profile parallel to the direction of travel(SegmentsAand E)and perpendicular to the direction of travel(SegmentsC and G).This information could be particularly useful in thestudy of surfaces that have texture with significant directionalchar