ASTM_D_4694_-_09_2015.pdf

Designation:D469409(Reapproved 2015)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 and health practices and determine the applica-bility of regulatory limitations prior to use.A specific hazardstatement is given in Section 6.2.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,Version4.1,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 to50C(10 to 120F)and shall tolerate relatively high humidity,rain or spray,and all other adverse conditions such as dust,shock,or vibrations that may normally be encountered.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 May 1,2015.Published August 2015.Originallyapproved in 1987.Last previous edition approved in 2009 as D4694 09.DOI:10.1520/D4694-09R15.2For 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 States1 5.1.2 Instruments Not Exposed to the Elements(inside thevehicle)shall be operable in the temperature range of 5 to 40C(40 to 105F).5.2 Force-Generating Device(falling“weight”)with aguide system.The force-generating device shall be capable ofbeing raised to one or more predetermined heights anddropped.The resulting force pulse transmitted to the pavementshall be reproducible within the requirements of 7.1.The forcepulse shall approximate the shape of a haversine or half-sinewave,and a peak force of approximately 50 kN(11 000 lbf)shall be achievable.NOT