RMIT Researchers Reimagine Rammed Earth Using Cardboard Tubes as Permanent Formwork

Researchers at the Royal Melbourne Institute of Technology (RMIT) in Australia have developed a groundbreaking construction material that encases rammed earth inside permanent cardboard tubes, eliminating the need for cement and significantly reducing embodied carbon. The system, known as CCRE (cardboard-confined rammed earth), offers a low-carbon, lightweight, and thermally efficient alternative for low-rise and modular architecture.

A low-carbon redesign of rammed earth

Traditional rammed earth relies on compacted soil mixed with 8–10% cement, processed within temporary timber or steel formwork that’s removed after curing. By contrast, RMIT’s method keeps the material continuously confined inside recycled cardboard, allowing the soil to maintain strength without cement stabilisation.

Published in Structures, the research suggests the material could be ready for commercial testing within one to two years — a promising timeline given the urgent demand for low-carbon building solutions.

Turning waste cardboard into structure

RMIT Cardboard waste is one of the fastest-growing waste streams globally, accelerated by e-commerce. In Australia alone, over 2.2 million tons of cardboard and paper were sent to landfill in 2020–21.

Lead researcher Dr Jiaming Ma sees CCRE as both a design solution and a sustainability strategy: “Repurposing cardboard for construction not only diverts it from landfill but transforms it into a valuable, ultra-low-carbon building resource.”

RMIT Cardboard - Strength through synergy

In CCRE, the cardboard serves as permanent formwork, performing two roles:

• shaping the column or wall during construction

• providing continuous confinement, which increases the rammed earth’s resistance to cracking and seismic forces

Meanwhile, the dense earth core reinforces the cardboard’s compressive performance by more than tenfold, creating a mutually strengthening composite.

The team cites influence from Shigeru Ban, known for pioneering the use of structural cardboard in architecture — including the celebrated Cardboard Cathedral in Christchurch.

Early results and next steps

Small-scale prototypes show that CCRE achieves a compressive strength comparable to cement-stabilised rammed earth, while carrying roughly one-quarter of concrete’s embodied carbon.

Researchers also developed a variation using carbon-fibre confinement, reaching strength levels similar to high-performance concrete.

Next phases of development include:

• full-scale CCRE columns

• new formwork geometries beyond cylinders

• foldable origami-inspired cardboard moulds for flat-pack, modular construction

The work suggests a future where soil + recycled cardboard become a scalable building system — lightweight, low-carbon, and deployable almost anywhere.