Engineers from the University of Durham have discovered that the strength of rammed earth, a sustainable building method, is dependent on water content, much like sandcastles.

Rammed earth is a simple material to make - mix some sand, gravel and clay, added water and compact. Rammed earth is becoming more popular as the construction industry tries to move away from cement (which accounts for 5% of man’s CO₂ output) to more sustainable resources.

The researchers say that their work could have implications for the future design of buildings as the link between strength and water becomes clear.

Research project leader, Dr Charles Augarde said: “We know that rammed earth can stand the test of time but the source of its strength has not been understood properly to date. Without this understanding we cannot effectively conserve old rammed earth or make economic designs for new build.”

The rammed earth technique was developed in China over 4,000 years ago where people used it to build walls. Current thinking in construction is coming back around to using the same techniques in a more optimised way. Tom Morton, Secretary of Earth Building UK, said: “This kind of research is very valuable as the construction industry analyses environmentally sound, traditional ways of building and adapts them for sustainable construction in the 21st century.”

By Leila Sattary