USCS Soil Classifier
The Unified Soil Classification System flowchart, rebuilt as an algorithm: enter the sieve and plasticity data, get the group symbol with every branch of the reasoning shown — and the plasticity chart with your soil plotted against the A-line. Covers §26.0 (ASTM D2487 logic).
Soil Data
Plasticity chart: A-line PI = 0.73(LL − 20); your soil is the red point (drawn when fines govern). FIG. E18-1
USCS asks only three questions, in order: how much is fine (passing #200)? Of the coarse part, is it gravel or sand? And do the fines behave like clay or silt (the A-line decides)? Every symbol — GW to PT — is an answer to those three.