16.4. Subgrade and Sub-base Preparation

Try these first

1. 1.

   What is the minimum compaction percentage for subgrade preparation?

   Hint

   It’s a percentage related to soil compaction.

2. 2.

   What material is often used for sub-bases?

   Hint

   Think about stable materials that can handle loads.

3. 3.

   What is the required compaction level for subgrade?

   • 85%
   • 90%
   • 95%

   Hint

   It’s a percentage, make sure it’s high enough!

4. 4.

   True or False: The sub-base can be made from organic materials.

   • True
   • False

   Hint

   Think about the stability of the materials.

5. 5.

   Given a scenario where pavement has multiple cracks developing after a year, analyze the potential issues with the subgrade preparation and suggest corrective actions.

   Hint

   Look at the factors contributing to soil stability.

6. 6.

   If the sub-base depth is reduced from the standard 150 mm to 80 mm, describe the effects this might have on pavement performance in heavy traffic areas.

   Hint

   Think about how the thickness affects weight support.