June 9, 2009

Study determines strength of rammed earth

British engineers say the secret of sandcastle construction could help revive an ancient building technique that uses rammed earth.

Durham University researchers said they conducted a study into the strength of rammed earth, which is growing in popularity as a sustainable building method. They determined that as a sandcastle needs a little water to stand up, the strength of rammed earth was heavily dependent on its water content.

Rammed earth is a manufactured material made of sand, gravel and clay that is moistened and then compacted between forms to build walls.

The researchers led by Charles Augarde of Durham University's School of Engineering said their findings could have implications for the future design of buildings using rammed earth.

We know that rammed earth can stand the test of time, but the source of its strength has not been understood properly to date, Augarde said. Without this understanding we cannot effectively conserve old rammed earth or make economic designs for new build. Our initial tests point to its main source of strength being linked to its water content.

The research appears in the journal Geotechnique.