Phase Relations & Classification

Worked: from three numbers

w = 18%, G_s = 2.70, S = 90%. e = 0.18 × 2.70/0.90 = 0.54, and γ_d = 2.70 × 62.4/1.54 = 109 pcf.

• USCS: coarse-grained if more than half is retained on the No. 200 sieve; then gravel or sand by the No. 4 sieve.
• Plasticity index PI = LL − PL. The A-line, PI = 0.73(LL − 20), separates clays (above) from silts (below); LL = 50 separates low from high plasticity.