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Figure  13-6B.Reverse  of  data  sheet  (DD  Form  1215)  for  sand-cone  method.
CBR Test Equipment and Tools - 14071_279

Engineering Aid 2 - Intermediate Structural engineering guide book
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Figure  13-7.—Nuclear  moisture-density  meter. moisture-density  meter,  such  as  the  one  illustrated  in and receive certification through the Naval figure 13-7. The  meter  contains  sealed  radioactive  materials, typically cesium and a combination of americium mixed with  beryllium  powder.  The  cesium  emits  gamma radiation that the detector in the meter can count when it is passed through the soil. This count can be translated to   density.   The   americium,   interacting   with   the beryllium,  emits  neutrons  following  collision  with hydrogen that are moderated and detected by the meter. The moisture content can be determined by measuring the  hydrogen  concentration  in  the  soil. When you are using the moisture-density meter, counts  or  readings  are  obtained  and  used  with  a calibration  chart  to  determine  the  wet  density  and moisture content. The dry density is computed from the wet density. CAUTION Before using the nuclear moisture-density meter, you must complete specialized training Construction Training Center at either Gulfport, Mississippi,  or  Port  Hueneme,  California. BEARING TESTS The bearing capacity of a soil is expressed in terms of shear resistance, which means the capacity of the load-bearing portion of a material or member to resist displacement in the direction of the force exerted by the load. There  are  various  types  of  load-bearing  tests.  For description   purposes   we   will   briefly   discuss   the California bearing ratio (CBR) test. The California bearing ratio  is a measure of the shearing resistance of a soil under carefully controlled conditions  of  density  and  moisture.  The  CBR  is determined by a penetration shear test and is used with empirical curves for designing flexible pavements. The test procedure used to determine the CBR consists  of  two  principal  steps.  First,  the  soil  test 13-10







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