16.4.1. Subgrade

Try these first

1. 1.

   What is the minimum percentage of Modified Proctor Density required for the subgrade?

   Hint

   Remember, it’s a percentage of the modified density.

2. 2.

   What should the subgrade be free from?

   Hint

   Think about what would weaken a foundation.

3. 3.

   What is the minimum compaction requirement for subgrade?

   • 85%
   • 90%
   • 95%

   Hint

   Look for the critical percentage in our discussions.

4. 4.

   True or False: Organic material is acceptable for a stable subgrade.

   • True
   • False

   Hint

   Think about what happens to organic materials over time.

5. 5.

   Suppose a new pavement is showing signs of cracking after only two years of service. Analyze potential reasons and link them to subgrade conditions.

   Hint

   Think about the preparation phases we discussed.

6. 6.

   Design a subgrade preparation strategy for a region known for heavy rainfall and clay soil. What specific techniques would you incorporate?

   Hint

   Consider the effects of heavy rain on soil stability.