The measure of water content in compacted soil that affects its pliability is called?

• A. Crystalline
• B. Riprap
• C. Plasticity index
• D. Backhauling

Answer: (C)

Plasticity index is the measure of the water content range over which soil behaves plastically, affecting its pliability. It’s defined as the difference between the liquid limit (the moisture content where soil changes from plastic to liquid) and the plastic limit (where soil changes from semi-solid to plastic). This range tells you how workable the soil is when compacted: a larger PI means the soil can remain plastic and moldable over a wider moisture window, aiding compaction and shaping. The other terms don’t describe moisture ranges or soil plasticity: crystalline relates to mineral structure, riprap is rock used for protection, and backhauling is a logistics term.