Relative Consistency (I_C) is defined as ratio of the

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JKSSB JE Civil Jal Shakti 5 Dec 2022 Official Paper (Shift 1)

Answer 1

Explanation:

Consistency index/ Relative Consistency (IC) :

The in-situ behavior of saturated fine-grained soil at its natural water content is represented by the consistency index.
It is defined as the ratio of Liquid limit minus the natural water content to plasticity index.
\(I_{c}=\frac{w_{l}-w_{n}}{I_{p}}\) , where, w_l = liquid limit, w_n= natural water content , I_p = plasticity index = w_l- w_p , w_p = plastic limit
If w_n > w_l ⇒ soil behaves like liquid (I_c < 0)
If wn < w_p ⇒ soil is in the solid or semi-solid state (Ic >1)
If wp< wn< wl ⇒ soil is in plastic state(0< Ic< 1)

Important Points Liquidity Index (I_L):

It signifies the same as that of the consistency index
It is defined as the ratio of the difference of natural water content and plasticity limit to the plasticity index.
\(I_{L}=\frac{w_{n}-w_{p}}{I_{p}}\) , where, wl = liquid limit, wn = natural water content , Ip = plasticity index = wl - wp , wp = plastic limit

Stage	Description	I_c	I_L	Unconfined compressive strength (kg/cm²)
Liquid	Liquid	< 0	> 1	-
Plastic	Very soft	0- 0.25	1.0-0.75	0-0.25
	Soft	0.25 - 0.50	0.75-0.50	0.25-0.50
	medium stiff	0.50-.075	0.50 - 0.25	0.50-1.0
	stiff	0.75 -1.0	0.25 - 0	1.0-2.0
Semi-solid	very stiff	> 1.0	< 0	2.0 - 4.0
Solid	Hard to very hard	> 1.0	< 0	> 4.0