Question

The standard load used in the estimation of subgrade CBR corresponding to 5 mm standard penetration is .......

• A. 1375 kg
• B. 1355 kg
• C. 2055 kg
• D. 2050 kg

Hint:

In CBR testing, the standard loads at 2.5 mm and 5 mm penetrations are reference values used to calculate the CBR percentage. The higher of the two corresponding CBR values is generally taken as the result.

Answer 1

The Correct Option is C

Step 1: Understand the context of CBR (California Bearing Ratio)
CBR is a penetration test used to evaluate the subgrade strength of roads and pavements.
Step 2: Recall the standard CBR testing procedure
In the CBR test, a standard plunger of 50 mm diameter is penetrated into the soil sample at a rate of 1.25 mm/min.
Step 3: Note the standard loads used in the test
The standard loads corresponding to the penetration depths are:
- At 2.5 mm penetration: 1370 kg
- At 5.0 mm penetration: 2055 kg
Step 4: Identify the required value from the question
The question asks for the standard load corresponding to 5 mm penetration.
Step 5: Final Answer
The standard load at 5 mm penetration is 2055 kg.