Engineers at RMIT University have developed cardboard-confined rammed earth, a building material made from cardboard, soil and water. It has roughly a quarter of the carbon footprint of concrete and is fully reusable and recyclable.

“By simply using cardboard, soil and water, we can make walls robust enough to support low-rise buildings,” lead author Dr Jiaming Ma says.

“This innovation could revolutionise building design and construction, using locally sourced materials that are easier to recycle.”

Emeritus Professor Yi Min ‘Mike’ Xie highlighted the practical benefits: “Instead of hauling in tonnes of bricks, steel and concrete, builders would only need lightweight cardboard, as nearly all material can be obtained on site.”

“This would significantly cut transport costs, simplify logistics and reduce upfront material demands.”

The material can be produced on-site by compacting the soil-and-water mixture inside cardboard formwork. Its thermal mass naturally regulates indoor temperatures, reducing the need for mechanical cooling.

The team has developed a formula to measure strength based on cardboard thickness. In a related study, carbon fibre combined with rammed earth achieved strength comparable to high-performance concrete.