2.6. Consistency, Flow, and Tough Index

Question 1

the liquid limit of the soil, minus the
natural moisture content, divided by
the PI; related to the LI and is an indicator of the relative shear strength

Answer 1

consistency index

Question 2

the slope of the flow curve; A low number (flat slope) indicates that a small change in moisture content is likely to produce a significant change in the soil consistency

Answer 2

Flow Index

Question 3

the ratio of plasticity index (IP) of the soil to the flow index (IF) of the soil; varies between 0 to 3; gives us an idea of the shear strength of soil at its plastic
limit

Answer 3

Toughness Index

if IT<1 soil is considered to easily friable at plastic limit