RMIT engineers have developed cardboard‑confined rammed earth, a building material made from soil, water and recycled cardboard that produces roughly 25% of the carbon footprint of standard concrete. The technique compacts soil inside cardboard molds to form load‑bearing walls suitable for low‑rise buildings and can often be produced on‑site, lowering transport and material needs. The team says the approach could cut construction emissions and divert cardboard from landfill, but further testing and code approvals are needed before wide adoption.
Cardboard‑Confined Rammed Earth: RMIT’s Low‑Carbon Alternative to Concrete
RMIT engineers have developed cardboard‑confined rammed earth, a building material made from soil, water and recycled cardboard that produces roughly 25% of the carbon footprint of standard concrete. The technique compacts soil inside cardboard molds to form load‑bearing walls suitable for low‑rise buildings and can often be produced on‑site, lowering transport and material needs. The team says the approach could cut construction emissions and divert cardboard from landfill, but further testing and code approvals are needed before wide adoption.
10:53 PM, 11/11/2025Environment
Engineers unveil low‑carbon building material made from soil, water and recycled cardboard
An Australian research team at RMIT University has developed cardboard‑confined rammed earth, a low‑cost building material that combines compacted soil, water and recycled cardboard to create load‑bearing walls and panels. According to NanoWerk, the material produces about 25% of the carbon footprint of conventional concrete and diverts cardboard from landfill, addressing two major environmental problems simultaneously.
Why it matters
Cement and concrete production are responsible for roughly 8% of global CO2 emissions, largely because making cement requires heating limestone in energy‑intensive kilns, estimates from Princeton University show. At the same time, Australia sends more than 2.2 million tonnes of cardboard and paper to landfill each year. By using recycled cardboard as formwork to confine compacted earth, the RMIT team aims to reduce both emissions and waste.
How it works
The method is straightforward: builders compact a soil‑and‑water mix inside cardboard molds to form dense, load‑bearing blocks or wall panels. The cardboard forms provide temporary confinement during compaction and can be recycled afterward, while the compacted earth provides structural mass. RMIT researchers report the material is strong enough to support low‑rise buildings without relying on cement.
"By simply using cardboard, soil, and water, we can make walls robust enough to support low‑rise buildings," said Jiaming Ma, the study's lead author.
Practical and environmental benefits
Compared with conventional concrete, cardboard‑confined rammed earth requires far fewer manufactured materials and can often be produced on‑site, reducing transport costs and supply chain needs. Emeritus Professor Yi Min (Mike) Xie, a co‑author, noted that relying on lightweight cardboard instead of tonnes of delivered materials could significantly simplify logistics.
Rammed earth also offers thermal mass benefits: thick earth walls help regulate indoor temperatures naturally, which can reduce reliance on air conditioning and lower long‑term energy bills, particularly in hot, dry climates.
Limits, next steps and commercialization
While promising, the approach requires further validation. Key next steps include long‑term durability testing (including moisture and freeze‑thaw resistance), fire performance, compliance with building codes, and lifecycle assessments across diverse climates and soil types. The RMIT team is actively seeking industry partners to run larger‑scale trials and adapt the method for commercial construction.
Bottom line: If scaled and standardized, a simple mix of soil, water and recycled cardboard could help cut construction emissions and reduce waste streams — potentially making building more sustainable and affordable worldwide.