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Calculator · Sheet T-209

Swell and shrink converter

Convert between bank (in place), loose (in the truck) and compacted (in the fill) volumes for common materials.

Swell & shrink converter · Sheet T-209Metric
m³
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Estimates only. Check quantities against the drawings and your supplier before ordering.

STA 0+120How it works

Every volume is converted to bank cubic metres first, then to loose (× swell ratio) and compacted (× compaction ratio).

STA 0+240Assumptions and sources

Per bank cubic metre: clay 1.43 loose / 0.90 compacted; loam 1.25 / 0.90; sand or gravel 1.11 / 0.95; blasted rock 1.50 / 1.301111. Averages only; moisture and gradation change them.

Questions people ask

What is the swell factor of clay?

About 1.43: one bank cubic metre of clay becomes about 1.43 loose cubic metres once dug1.

What is a shrink factor?

The ratio of compacted volume to bank volume. For clay it is about 0.90, so a bank cubic metre compacts to 0.90 m³1.

Why does rock not shrink back?

Blasted rock cannot be compacted back to its solid state: one bank cubic metre is about 1.30 m³ even after compaction1.

Sources

  1. FM 5-434 Earthmoving Operations, Chapter 1, Tables 1-1 and 1-2U.S. Department of the Army (field manual; hosted copy on GlobalSecurity.org) · FM 5-434 (2000)