Weighted plasticity index & base suitability calculator

Inputs in the worked example

The live calculator starts with these values; change any of them and every result, check and diagram updates instantly.

Worked example — results

• ✓ WPI ≤ limit

Method, formulas and assumptions

• WPI = PI × %passing 0.425 = 8*22 = 176
• Plasticity modulus PI × P425 (same index, %·%) = 176 = 176
• Weighted LS = LS × P425 = 3.5*22 = 77

Related pavements & traffic calculators

• Asphalt volumetrics (Marshall) — Air voids, VMA and VFA from bulk and maximum densities, with Marshall stability and flow checks.
• Flexible pavement: mechanistic check (CIRCLY-style) — Mechanistic check of a flexible pavement under the Austroads Standard Axle. Layers are transformed by…
• Concrete (rigid) pavement thickness — Plain concrete pavement or hardstand under a design axle. The subgrade reaction k comes from the CBR and is…
• Asphalt overlay from FWD deflections — Falling-weight deflectometer bowls at each test point give the surface modulus (from D0), the subgrade…
• Design traffic (ESA) for pavements — Cumulative heavy vehicle axle groups and ESAs over the design period with compound growth.
• Granular pavement thickness (thin surfacing) — Total granular cover above the subgrade from CBR and design traffic: t = [219 − 211 log CBR + 58 (log CBR)²]…