21.2. Sub grade soil

Try these first

1. 1.

   What is sub grade soil?

   Hint

   Think about the role it plays below the road surface.

2. 2.

   Name one test used to evaluate sub grade soil.

   Hint

   It's a test specifically focused on strength.

3. 3.

   What is the main function of sub grade soil?

   • To drain water
   • To support pavement
   • To absorb heat

   Hint

   Consider what role the soil plays beneath the road.

4. 4.

   The CBR test measures what aspect of sub grade soil?

   • Color
   • Strength
   • Moisture

   Hint

   Think about how engineers need to measure the resistance of soil.

5. 5.

   Given a site with identified clay sub grade soil, discuss the implications for pavement design and suggest methods to improve its load-bearing capacity.

   Hint

   Think about the adaptive measures engineers take for problematic soils.

6. 6.

   Analyze the results of a CBR test yielding a value of 3%. Discuss what design alterations may be necessary for the pavement.

   Hint

   Recall how lower CBR values require more substantial engineering interventions.