Soil Testing Equipment

1. SCOPE
    Description of  Test
          This method describes the sampling of the subgrade for California Bearing Ratio  (C.B.R.).  The  resulting information is used for pavement design thickness.

2. APPARATUS AND MATERIALS
Equipment Required

1. A suitable rig equipped with a 150 mm auger.
2. Large cotton bags (with tags).

3. PROCEDURE
Test Procedure

1. Take a 35 kg sample at every third group index sample location, spacing may be increased on projects where the material is found to be very uniform.  The district materials engineer or his designate will advise on the spacing of sampling. Extreme care must be taken to ensure the sample is not contaminated with prepared  Subgrade material (top 5 - 15 cm). 
2. Take a group index sample and C.B.R. sample from the same hole.  
3. The group index sample is taken first, then enlarge the hole to obtain the C.B.R. sample.  
4. Ensure neither sample is contaminated from loose surface materials.
5. Record control section, station and offset at which the sample was taken on two tags.   
6. Place one tag inside the bag and attach the other to the outside of the bag. 
7. Keep samples dry while stored in the field and transport to the district lab at earliest  opportune time. A special trip is not required.

4. RESULTS AND CALCULATIONS
Reporting Results
Record control section, hole number, stationing and offset for further testing as proctor density is completed in the district lab and the C.B.R. testing is completed at the central lab in Regina.

5. ADDED INFORMATION
General
Refer to diagram in STP 104-5 for sampling procedure.
C.B.R. sampling is required on all subgrade types with the exception of clean sands