Researchers at RMIT University in Australia have developed a new building material that could cut the carbon footprint of construction while tackling waste. The innovation, called cardboard-confined rammed earth, combines waste cardboard with soil and water to create strong, low-cost walls for low-rise buildings.

A Circular Alternative to Concrete

Concrete is responsible for about 8% of global carbon emissions. At the same time, more than 2.2 million tonnes of cardboard and paper are sent to landfill each year in Australia. The RMIT team addresses both issues by replacing cement with recycled cardboard. The result is a material with just a quarter of the carbon footprint of concrete at less than one third of the cost.

How It Works

The process is simple. Builders compact a mixture of soil and water inside cardboard tubes, which serve as moulds. The tubes can be filled manually or with machines, making the system easy to use on construction sites. Once hardened, the walls are robust, with strength depending on the thickness of the cardboard.

Practical Benefits

Using cardboard and local soil reduces the need to transport heavy materials such as steel, bricks, or concrete. This lowers both costs and emissions. Rammed earth walls also have a high thermal mass, which helps regulate indoor temperatures in hot climates. As a result, buildings require less mechanical cooling, further cutting energy use.

The research group has also tested carbon fibre with rammed earth. These trials show strength levels comparable to high-performance concrete, opening more possibilities for sustainable building.

Towards Scalable Applications

The RMIT team believes cardboard-confined rammed earth could be ideal for low-rise housing, community buildings, and off-grid projects. The material supports a growing global interest in earth-based construction and the use of local, circular resources.

By transforming waste into structure, the research points to a future where sustainable building materials are not only greener, but also cheaper and easier to produce.

Source & photo: RMIT University