ASTM_D_4694_-_09_2020.pdf

Designation:D469409(Reapproved 2020)Standard Test Method forDeflections with a Falling-Weight-Type Impulse LoadDevice1This standard is issued under the fixed designation D4694;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 measurement of deflectionsof paved and unpaved surfaces with a falling-weight-typeimpulse load device.These devices are commonly referred toas falling-weight deflectometers or FWDs.1.2 This test method describes the measurement of verticaldeflection response of the surface to an impulse load applied tothe pavement surface.Vertical deflections are measured on theload axis and at points spaced radially outward from the loadaxis.1.3 The values stated in SI units are to be regarded as thestandard.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.Aspecific hazard statement is given in Section 6.1.5 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:2D4695 Guide for General Pavement Deflection Measure-ments2.2 Strategic Highway Research Program:Long Term Pavement Performance Program Manual forFalling Weight Deflectometer Measurements,Version 4.1,December 20063.Summary of Test Method3.1 This test method is a type of plate-bearing test.The loadis a force pulse generated by a weight dropped on a buffersystem and is transmitted through a plate resting on thepavement surface.The test apparatus may be mounted in avehicle or on a suitable trailer towed by a vehicle.3.2 The vehicle is brought to a stop with the loading platepositioned over the desired test location.The plate and deflec-tion sensors are lowered to the pavement surface.The weightis raised to the height that,when dropped,will impart thedesired force to the pavement.The weight is dropped and theresulting vertical movement or deflection of the pavementsurface is measured using suitable instrumentation.Multipletests at the same or different heights of drop may be performedbefore the apparatus is then raised and moved to the next testsite.3.3 Peak pavement deflections at each measured locationresulting from the force pulse are recorded in micrometres,millimetres,mils,or inches,as appropriate.3.4 The peak force imparted by the falling weight ismeasured by a load cell and recorded as the force in kN or lbfor mean stress(the load divided by the plate area)in kN/m2orpsi,as appropriate.4.Significance and Use4.1 This test method covers the determination of pavementsurface deflections as a result of the application of an impulseload to the pavement surface.The resulting deflections aremeasured at the center of the applied load and at variousdistances away from the load.Deflections may be eithercorrelated directly to pavement performance or used to deter-mine the in-situ material characteristics of the pavement layers.Some uses of data include structural evaluation of loadcarrying capacity and determination of overlay thicknessrequirements for highway and airfield pavements.5.Apparatus5.1 Instrumentation System conforming to the followinggeneral requirements:5.1.1 Instruments Exposed to the Elements(outside thevehicle)shall be operable in the temperature range of 10 to1This 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 D4694 09(2015).DOI:10.1520/D4694-09R20.2For 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.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.50 C(10 to 120 F)and shall tolerate relatively high humidity,rain or spray