Cardboard-bound rammed earth as a cement-free wall material
A rammed earth column wrapped in cardboard and one wrapped in carbon-fiber polymer composite. (Photo: RMIT)
September 22 2025 – Researchers at the Royal Melbourne Institute of Technology (RMIT) in Australia have developed a new construction material made from nothing more than cardboard, earth (clay), and water. The earth is compacted inside cardboard tubes to form structural elements that, according to RMIT tests, are strong enough for low-rise buildings. This avoids the use of cement and reduces the CO₂ footprint to about one quarter of that of concrete. It is also expected to be cheaper: RMIT estimates the costs to be roughly one third lower than those of concrete. In addition, almost all raw materials can be sourced locally, which offers logistical advantages.
According to RMIT, rammed earth is especially suitable for buildings in warm climates because its high thermal mass naturally regulates indoor temperature and humidity. This reduces the need for mechanical cooling and lowers CO₂ emissions.
The team has also developed calculation rules to predict strength as a function of cardboard thickness and envisions applications in remote locations or emergency housing that could be upgraded to permanent use.
The research has been published (among others) in the journal Structures under the title Cardboard-confined rammed earth towards sustainable construction.
