Scientists Found a Way to Turn Recycled Cardboard Into Concrete-Like Material

Cardboard has become part of everyday life, whether it’s stacked by the front door after a round of deliveries or piled near warehouse loading bays. Most of it gets broken down, tossed in a bin, and never thought about again. A group of researchers at RMIT University in Australia has been looking at that steady stream of discarded boxes and wondering if it could do something more useful. Their experiments led to a mix of cardboard, soil, and water that behaves like a building material, not packaging. Early trials point to real potential, especially for builders who are trying to cut back on high-emission materials like concrete.

Learn how the material works, what the researchers found during testing, and why it could matter for construction in the coming years.

How Cardboard-Confined Rammed Earth Works

Researchers at RMIT describe their material as cardboard-confined rammed earth. The idea is pretty straightforward. They roll thick tubes out of cardboard, fill them with a mix of soil and water, and press that mix down until it becomes a solid core. The cardboard holds everything in place while it firms up, which gives the finished piece enough strength for smaller structures.

Rammed earth has been used for a long time, but many modern builders add cement to help stabilize it. The RMIT team skipped that step. The weight of the compacted soil and the support from the cardboard tube give the material its structure, so there’s no need for cement. That keeps the footprint low and makes the whole thing easier to reuse. Crews can put the tubes together on site, work with soil that’s already available, and skip hauling in heavy loads of concrete or brick.

Why The Material Matters For Future Building

Concrete remains a major source of global emissions, and construction teams continue looking for alternatives that hold up under load while reducing environmental impact.

Cardboard-confined rammed earth offers a practical option. Cardboard is lightweight and easy to transport. Soil is available on most job sites. When combined, they create a building material that eliminates the emissions associated with cement production.

The researchers developed a design formula that connects cardboard thickness to structural strength, giving builders a clear way to size columns and wall sections. In a separate study, the team combined carbon fiber with rammed earth, achieving strength levels comparable to those of high-performance concrete, suggesting that even stronger versions of the material may be possible.

Potential Applications and What Researchers Plan Next

The material works well in regions with soil suited for rammed-earth construction, including many parts of Australia. Because the approach relies on materials already available on site, it reduces the need for transporting bulk supplies and makes construction in remote areas more practical.

Rammed-earth walls also provide strong thermal mass. They absorb heat and release it gradually, which helps keep indoor temperatures steadier in hot climates. Cardboard-confined rammed earth offers the same advantage while keeping the overall footprint low.

RMIT researchers continue to refine the material and plan to collaborate with industry partners to test it in real-world projects. Their results point toward a future where familiar waste streams play a direct role in building more sustainable structures. Cardboard, often treated as a short-lived material, may become part of a new generation of lower-impact construction.

Sources:

• RMIT University, “Cardboard and earth reshape sustainable construction” 2025
• RMIT Research Repository, “Cardboard-confined rammed earth towards sustainable construction” 2025