Answer:
(a) 23
(b)-0.13
(c) In which consistency state was the in situ soil? Plastic limit = 1.1
Explanation:
(a) Compute the plasticity index of the soil.
The formula for plasticity index is given as
Plasticity Index = Liquid limit - Plastic limit
Liquid limit = 44
Plastic limit = 21
Plastics Index = 44 - 21
= 23
(b) Calculate the liquidity index of the in situ soil.
Liquidity Index = Water content - Plastic limit/Liquid limit - Plastic Limit
Water content = 18%
Plastic limit = 21
Liquid limit = 44
Liquidity Index =18 -21/44 - 21
- 3/23
= -0.1304347826
≈ -0.13
(c) In which consistency state was the in situ soil
The consistency state of a soil tells us how firm the soil is.
Consistency state/index = Liquid limit - Water content/ Plastic Index
= Liquid limit - Water content /Liquid limit - Plastic Limit
Water content of the in situ soil = 18%
=44 - 18/44 - 23
= 26/23
= 1.1304347826
= 1.1
Since the consistency index of this situ soil is above 1, it means the soil is at plastic limit.
