2.9. California Bearing Ratio (CBR) Test

Try these first

1. 1.

   What does CBR stand for?

   Hint

   Think of what this ratio measures related to soil strength.

2. 2.

   In a CBR test, what do we use to penetrate the soil?

   Hint

   What tool helps us measure the soil's load-bearing capacity?

3. 3.

   What does a higher CBR value indicate?

   • Weaker soil support
   • Stronger soil support
   • No effect on pavement

   Hint

   Consider the relationship between CBR values and soil capabilities.

4. 4.

   True or False: The CBR test is only performed on soaked samples.

   • True
   • False

   Hint

   Remember the different conditions we're testing.

5. 5.

   You are tasked to design a pavement over a soil with a CBR of 3%. If a similar road in a different location uses a CBR of 15%, discuss the design implications for thickness and materials.

   Hint

   Think about how the soil's strength impacts material choice.

6. 6.

   Given that the CBR is essential in preventing pavement failures, propose methods to improve the CBR value of a weak soil subgrade identified during testing.

   Hint

   Consider how construction techniques can influence soil properties.