ASTM_D_4748_-_10_2020.pdf

Designation:D474810(Reapproved 2020)Standard Test Method forDetermining the Thickness of Bound Pavement LayersUsing Short-Pulse Radar1This standard is issued under the fixed designation D4748;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 nondestructive determina-tion of the thickness of bound pavement layers using groundpenetrating radar(GPR).1.2 This test method may not be suitable for application topavements which exhibit increased conductivity due to theincreased attenuation of the electromagnetic signal.Examplesof scenarios which may cause this are:extremely moist or wet(saturated)pavements if free electrolytes are present and slagaggregate with high iron content.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific hazard statements are given in Section 11.1.5 This international 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)Committee.2.Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,Rock,and ContainedFluidsD6087 Test Method for Evaluating Asphalt-Covered Con-crete Bridge Decks Using Ground Penetrating RadarD6429 Guide for Selecting Surface Geophysical MethodsD6432 Guide for Using the Surface Ground PenetratingRadar Method for Subsurface InvestigationE1778 Terminology Relating to Pavement Distress3.Terminology3.1 Definitions:3.1.1 Definitions shall be in accordance with the terms andsymbols given in Terminologies D653 and E1778.3.1.2 Additional definitions can be found in subsection 3.1.3of Guide D6432,and in Ref(1).33.1.3 Additional Definitions:3.1.3.1 bound pavement layerupper layers of a pavementstructure consisting of aggregate materials mixed with cemen-titious binder such as bitumen or portland cement paste.Examples of bound pavement layers include bituminousconcrete,portland cement concrete,and stabilized bases.Bound pavement layers do not include granular base andsubbase materials.3.1.3.2 unbound pavement layerlower layers of a pave-ment structure consisting of untreated aggregate materials suchas sand,gravel,crushed stone,slag,and other stabilizedmaterials.Unbound pavement layers include base,subbase,and compacted subgrade.4.Apparatus4.1 The apparatus may consist of a vehicle or a cart that isequipped with the following:4.1.1 One or more GPR antennas mounted on the vehicle,cart,or on a trailer.4.1.1.1 The antenna for this application typically has acenter frequency that ranges from 1.0 to 2.6 GHz.A typical1.0 GHz antenna usually has a resolution sufficient to deter-mine a minimum layer thickness of 40 mm(1.5 in.)to anaccuracy of 65.0 mm(60.2 in.).Antennas emitting shortpulses containing a center frequency of 2.0 GHz and higherprovide resolution sufficient for determination of a minimumlayer thickness less than 25 mm(1.0 in.)to an accuracy of62.5 mm(60.1 in.).1This test method is under the jurisdiction of ASTM Committee E17 on Vehicle-Pavement Systems and is the direct responsibility of Subcommittee E17.41 onPavement Testing and Evaluation.Current edition approved Nov.1,2020.Published November 2020.Originallyapproved in 1987.Last previous edition approved in 2015 as D4748 10(2015).DOI:10.1520/D4748-10R20.2For 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.3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.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 theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.4.1.1.2 Two basic types of antenna systems are in use:(1)Air-launched antennas that are specifically designed toradiate into the air and are to be used at some distance abovethe pavement surface,typically 20 to 50 cm(8 to 20 in.).(2)Ground-coupled ant