California bearing ratio
CALIFORNIA BEARING RATIO
• CALIFORNIA BEARING RATIO
•EQUIPMENTS
CALIFORNIA BEARING RATIO
• CALIFORNIA BEARING RATIO
- CBR EQUIPMENT
- COMPACTION RAMMER
- EXPANSION MEASURING
APPARATUS
- SURCHARGE WEIGHTS
- COMPRESSION MACHINE
• CALIFORNIA BEARING RATIO
• CALIFORNIA BEARING RATIO
•NOTES
• CALIFORNIA BEARING RATIO
• Developed by the California Division of Highways in
1929
• is a penetration test for evaluation of the mechanical strength of road subgrades and base courses • U.S. Army Corps of Engineers adopted the test for airfield construction.
• It is currently used in pavement design for both roads and airfields.
• CALIFORNIA BEARING RATIO
• CBR value can be converted to modulus of subgrade reaction (ks) or to Resilient Modulus (MR) using empirical relationships.
• Laboratory CBR test measures the shearing resistance of a soil under controlled moisture and density condition
• The test can also be performed in the field on an inplace soil but uses a different equipment
• CALIFORNIA BEARING RATIO
•PROCEDURE
• CALIFORNIA BEARING RATIO
Unsoaked Sample
1. Prepare 2 molds of soil(12 kg fine grained passing sieve
No.4 or 15 kg depending on compaction standard) at optimum moisture content
2. Take representative sample for moisture content before compacting the soil (at least 100g) and weigh the two molds minus the base plate & collars.
3. Clamp a mold to the base plate, insert spacer disk and cover with a piece of filter paper.
• CALIFORNIA BEARING RATIO
4. Compact the soil according to ASTM D 698 or ASTM D 1557
Method B or D.
5. Remove the collar, trim the sample smooth and patch any holes that may have formed.
6. Remove the base plate and spacer disk, weigh the mold + compacted soil and compute wet mass, density and unit weight. 7. Repeat Steps 4 through 6 for the second mold which will be soaked. 8. Place a piece of filter paper on the base plate, invert the specimen and
• CALIFORNIA BEARING RATIO
•EQUIPMENTS
CALIFORNIA BEARING RATIO
• CALIFORNIA BEARING RATIO
- CBR EQUIPMENT
- COMPACTION RAMMER
- EXPANSION MEASURING
APPARATUS
- SURCHARGE WEIGHTS
- COMPRESSION MACHINE
• CALIFORNIA BEARING RATIO
• CALIFORNIA BEARING RATIO
•NOTES
• CALIFORNIA BEARING RATIO
• Developed by the California Division of Highways in
1929
• is a penetration test for evaluation of the mechanical strength of road subgrades and base courses • U.S. Army Corps of Engineers adopted the test for airfield construction.
• It is currently used in pavement design for both roads and airfields.
• CALIFORNIA BEARING RATIO
• CBR value can be converted to modulus of subgrade reaction (ks) or to Resilient Modulus (MR) using empirical relationships.
• Laboratory CBR test measures the shearing resistance of a soil under controlled moisture and density condition
• The test can also be performed in the field on an inplace soil but uses a different equipment
• CALIFORNIA BEARING RATIO
•PROCEDURE
• CALIFORNIA BEARING RATIO
Unsoaked Sample
1. Prepare 2 molds of soil(12 kg fine grained passing sieve
No.4 or 15 kg depending on compaction standard) at optimum moisture content
2. Take representative sample for moisture content before compacting the soil (at least 100g) and weigh the two molds minus the base plate & collars.
3. Clamp a mold to the base plate, insert spacer disk and cover with a piece of filter paper.
• CALIFORNIA BEARING RATIO
4. Compact the soil according to ASTM D 698 or ASTM D 1557
Method B or D.
5. Remove the collar, trim the sample smooth and patch any holes that may have formed.
6. Remove the base plate and spacer disk, weigh the mold + compacted soil and compute wet mass, density and unit weight. 7. Repeat Steps 4 through 6 for the second mold which will be soaked. 8. Place a piece of filter paper on the base plate, invert the specimen and