TM 5-6635-386-12&P Use this to good advantage by extending the use of the tester to become a good AC content tester for field use. Some additional hardware is required a. Metal pan, approximately 16" x 16" x 4". b. Compaction   plate...5"   x   5"   x   1/2"   with   a   rod welded to it and a sliding weight to slide on the rod and permit a controlled compaction effort on the plate. c. Accurate scale to approximately 30 pounds. d. Straight edge and a finely graduated metal ruler. ..  C-clamp to clamp the ruler to the straight edge.  The straight  edge  should  be  approximately  twice  as  long  as the pan’s longest dimension. Procedure Establish   an   initial   calibration   curve   in   the   laboratory. After  that,  the  same  procedure  is  used  in  the  field  to establish the desired asphalt content value. Prepare   a   sample   of   asphaltic   concrete   at   a   specific weight  each  time.    This  weight  will  be  selected  at  the outset and will be used for the initial calibration as well as for all subsequent field tests. This weight should be approximately 95% of optimum for the   typical   asphalt   weights   used   in   the   user’s   locale. Round  it  off  to  a  practical  value  for  ease  of  preparation and calculations. Initially   prepare   a   sample   at   a   known   density,   evenly compacted     in     the     pan     in     one     inch     thick     layers. Thereafter   prepare   the   sample   in   the   same   one   inch layers for all field work using the same technique exactly. a. Measure   the   pan   and   determine   precisely   the volume  in  each  inch  for  the  bottom  three  inches.    The fourth inch will merely become a catch basin for the light material that is compacted into the third inch. If a 16" square pan was used, then each inch would hold precisely 0.1481 cubic feet. Establish   a   density   to   be   compacted   in   the   pan each time.  .  this is 135 pounds/cubic feet, a value that is  about  95%  of  optimum  for  the  region  that  is  going  to use this test.  It will vary, of course, for different parts of the world. If the desired density is 135 PCF, and if each inch in the  pan  represents  0.1481  cubic  feet  then  a  one  inch layer compacted to 135 PCF would actually weigh 19.99 pounds. 135 PCF x 0.1481 CF = 19.993 pounds. b. Measure out exactly 19.99 pounds of hot AC mix and dump this into the pan. Spread it around evenly and then compact it down to a depth of exactly one inch. A 1/16th inch error in height is equal to a 6% error in final compaction.  .  an error of 8.1 PCF, something not accepted or calibration work. c. Compact   a   second   and   third   lift   in   the   same manner. Weigh  the  final  pan  of  material  and  it  should  weigh exactly 3 x 19.99 = 59.97 pounds plus tare. d. Set the pan atop the tester shipping case in the same   manner   as   you   would   take   a   standard   count. Remove the reference standard from the case. e. Take   several   tester   moisture   readings   on   the compacted  surface,  revolving  the  tester  900  each  time. Record the readings. f. Run an extraction of a sample of the compacted material to determine asphalt content. g. Plot  the  tester  reading  (in  ratio)  on  the  vertical axis  of  a  calibration  sheet  similar  to  that  used  fur  the CPN    moisture    curve,    and    plot    the    asphalt    content PERCENTAGE across the bottom. This curve is now an accurate asphalt content curve. Zero     is     obtained     by     compacting     a bone dry 1-21