Dupont Clay CBR

Dupont Clay CBR, Density, and Vane Shear Data

Dupont Clay CBR and Density Data    Dupont Clay CBR, Density, and Vane Shear Data Summary

 Dupont Clay Vane Shear Data



The Dupont Clay was constructed in seven separate lifts for this project.  CBR data was collected on each lift with two separate test locations.  An average of the two tests was used for determining the CBR value of each lift.  CBR values for the Dupont Clay ranged between 5 and 7.



Density testing was performed on the Dupont Clay in the form of drive cylinders.  Because of the digging required to remove a drive cylinder tube, tests were not performed on the first lift due to mixing of materials at the bottom interface.  Also, because of digging, testing was not performed on the last lift in order to eliminate any holes before placement of the subsequent subbase or base course.  Three drive cylinders were taken in separate locations from lifts 2 through 6.  Testing provided moisture content and in-situ wet and dry density conditions.  Averages of the three values present moisture contents in the range of 30 - 34 percent for each lift.  Also, an average wet density range of 115 to 117.5 lb/cu ft and an average dry density range of 85.5 to 89.5 lb/cu ft were determined.


Vane Shear

Vane shear testing was performed on all lifts of the Dupont Clay.  Lifts 1 through 6 of the subgrade had between 72 and 90 vane shear readings taken per lift.  On the top lift 54 vane shear readings were performed.  Vane shear data was taken in various locations in triplicate.  The average of the three readings per location provided an estimated CBR value.  The CBR values for each lift were then average for an estimated CBR value for the entire lift.  Average CBR values for the lifts ranged between 8 and 10.