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Soil Reactivity — AS 2870 Shrink-Swell Checks In Your Browser.

Characteristic surface movement (ys) and AS 2870 site classification from shrink-swell index (Iss) test results — with regional presets, live depth profiles and print-ready reports. Nothing to install — it runs entirely in your browser and is free with a KeoGeo sign-in.

Soil Reactivity web app — regional inputs, editable soil profile, and live suction and restraint depth profiles

One screen: regional inputs and the soil profile on the left, suction and restraint depth profiles drawn live on the right.

What It Does

A Full AS 2870 Reactivity Check, Without The Spreadsheet.

Soil Reactivity computes the characteristic surface movement of a reactive site to AS 2870 (Cl 2.3.1 & Appendix D) and classifies the site for you:

  • Regional presets — suction change (Δu), suction depth (Hs) and crack depth factors for 11 Australian localities, all overridable, plus custom entry.
  • Editable soil profile — layers split automatically at the crack depth and suction depth; the per-layer breakdown updates live.
  • Groundwater — optionally truncate the suction profile at a shallow water table.
  • Live depth profiles — suction (Δu) and restraint factor (α) drawn side by side on a shared depth scale.
  • Built-in verification — the source-spreadsheet reference case plus two closed-form checks, re-run automatically on every change.
  • Print-to-PDF reports — coefficient provenance, preparer, date and a session code that restores the exact inputs.
  • Site classification — S / M / H1 / H2 / E per AS 2870 Table 2.3, with ys rounded to the nearest 5 mm.

Need to run many cases? KeoGeo Pro adds a CSV batch processor to this tool — A$20/month, cancel any time.

Example Outputs

What You Get Out Of It.

Surface Movement

Characteristic surface movement ys in millimetres with the governing per-layer contributions, and the AS 2870 site class (S, M, H1, H2 or E).

Depth Profiles

Suction change Δu and restraint factor α drawn against depth on a shared scale, including the cracked zone and any water-table truncation.

PDF Report

A print-ready calculation report with inputs, coefficient provenance, verification status and a session code — ready for a design appendix.