CBR Test

The California Bearing Ratio (CBR) is a degree of the strength of the subgrade of a road or other paved area, and of the materials used in its construction. The CBR is the ratio of the bearing load that penetrates a material to a specific depth compared with the load giving the same penetration into crushed stone. Penetration is measured by applying the bearing load on the sample using a standard plunger of diameter 50 mm at the rate of 1.25 mm/min. The CBR is expressed as a percentage of the actual load causing the penetrations of 2.5 mm or 5.0 mm to the standard loads on crushed stone. A load penetration curve is drawn. The load values on standard crushed stones are 1,370 kgf (13.44 kN) and 2,055 kgf (20.15 kN) at 2.5 mm and 5.0 mm penetrations respectively. With "CiviLab" you can easily do the calculations of this test, plot the various curves and correctly archive them. Also, CiviLab provides high quality reports.

In the CBR test you can use CiviLab to:

• Perform the calculations according to the standards:
  • ASTM D1883-99;
  • AASHTO T 193;
  • VTM-8;
  • NF P 94-078;
  • BS 1377-9:1990;
  • NA 5252.
• Draw the stress (or loads) -penetration curve using the following methods :
  • Linear;
  • Culic spline;
  • Culic spline Akima;
  • Culic spline Pchip;
  • B-spline;
  • Least square method.
• Draw the CBR index-Water content curve;
• Draw the CBR index-density curve ;
• Save and print results appropriately.