A stiff metal ring (usually made of brass or stainless steel) that holds the soil. This forces all volume changes to occur strictly in the vertical (one-dimensional) direction.

: Updated formulas for calculating percent swell and swell pressure to reduce interpretation errors.

Which specific procedure () does your project specification require?

Do not rely on previous editions. Do not risk using a pirated copy. Purchase the official from ASTM International or an authorized reseller. The cost of the PDF is negligible compared to the cost of a foundation failure.