What is the Slope of flow curve?
- ALiquidity Index
- BConsistency Index
- CFlow IndexCorrect
- DPlasticity Index
Solution
Concept
Definition of soil flow index parameter
Formula
NONE
Step-by-step solution
1. A flow curve is plotted between water content on the vertical axis and the logarithm of the number of blows on the horizontal axis during a liquid limit test. 2. The slope of this flow curve represents the rate of loss of shear strength with an increase in water content. 3. This slope is defined as the Flow Index. Answer: C
Explanation
The flow curve is obtained from the Casagrande liquid limit test by plotting water content against the logarithm of the number of blows. The slope of this flow curve defines the flow index of the soil. It measures the rate at which a soil loses its shear strength as its moisture content increases.
Why the other options are wrong
A) Liquidity index measures the relative consistency of soil at its natural moisture content. B) Consistency index indicates the relative firmness of soil compared to its liquid limit. D) Plasticity index is the numerical difference between the liquid limit and plastic limit.
Shortcut
Slope of Flow curve = Flow Index.
Common mistake
Confusing the Flow Index with the Plasticity Index or Liquidity Index.
Correct answer: C) Flow Index