Question

A soil has a Liquid Limit of 40% and Plastic Limit of 30%. If its Flow Index is 20%, the corresponding Toughness Index would be
1. 0.25
2. 0.50
3. 0.75
4. 1.00

Answer 1

Correct Answer - Option 2 : 0.50

Concept:

Toughness Index: Toughness index is defined as the ratio of plasticity index (IP) of the soil to the flow index (IF) of the soil.

The toughness index varies between 0 to 3.

Calculation:

Given,

LL = 40% PL = 30%, Flow Index = 20

Plasticity Index = LL - PL = 40 - 30 = 10%

\(\begin{array}{l} Toughess\;index = \frac{{Plasticity\;index}}{{Flow\;index}}\\ \end{array}\)

Toughness index = 10/20 

Toughness index = 0.5