Turning waste into walls: How cardboard and soil could replace concrete

Cement and concrete have built much of our modern world, but they come with a heavy price – massive carbon emissions and mountains of waste. Now, engineers have come up with a low-tech, low-cost building material that flips the script.

The new wall material is made from little more than soil, water, and cardboard, yet it shows the strength and stability needed for real buildings while dramatically reducing the footprint of construction dramatically.

The concept comes from a team in Australia, where researchers at RMIT University combined the age-old strength of rammed earth with the versatility of cardboard.

The goal was simple: replace high-emission materials with something local, recyclable, and affordable – without giving up performance.

Soil and cardboard for building

Rammed earth is usually made by packing damp soil inside forms, then letting it cure into dense, stone-like layers. Modern versions often add cement for extra strength.

Here, the team swapped the usual timber or metal forms for structural cardboard tubes and shells that stay in place and confine the compacted soil.

The “mix” is just soil and water – no kiln-fired cement or steel. When a wall reaches the end of its life, the materials can be disassembled and returned to the loop.

“Modern rammed earth construction compacts soil with added cement for strength. Cement use is excessive given the natural thickness of rammed earth walls,” noted study lead author Dr Jiaming Ma.

Why this matters now

Cement and concrete account for a notable slice of global emissions. At the same time, mountains of packaging end up in the ground.

In Australia alone, more than 2.2 million tons of cardboard and paper go to landfills each year. Turning that stream into structure tackles both problems at once: fewer emissions up front and less waste at the back end.

Cardboard-confined rammed earth removes cement from the recipe entirely. In testing, the team estimates it carries about one-quarter the carbon footprint of concrete at under one-third of the cost. The ingredients are close at hand, too. That makes the material a fit for local building where supply chains are long or budgets are thin.

“By simply using cardboard, soil, and water, we can make walls robust enough to support low-rise buildings,” said Dr. Ma. “This innovation could revolutionize building design and construction, using locally sourced materials that are easier to recycle.”

“It also reflects the global revival of earth-based construction fueled by net zero goals and interest in local sustainable materials.”

Built on site, with lighter logistics

Because the walls are formed by compacting soil inside cardboard on site, builders don’t need to haul heavy, high-embodied-carbon products over long distances. Crews can ram by hand for small projects or use compactors for larger ones.

The soil comes from the site or nearby pits. The cardboard arrives flat and light, then becomes the permanent confinement that gives the wall shape and strength.

“Instead of hauling in tons of bricks, steel, and concrete, builders would only need to bring lightweight cardboard, as nearly all material can be obtained on site,” said Professor Yi Min “Mike” Xie. “This would significantly cut transport costs, simplify logistics and reduce upfront material demands.”

Cooling indoor temperatures naturally

Rammed earth shines where summers are harsh. Thick, dense walls soak up heat by day and release it slowly at night, trimming the need for air conditioning.

Australia’s red soils are common in regional areas and often ideal for rammed earth. The new approach plays to those strengths while making the recipe simpler.

“Rammed earth buildings are ideal in hot climates because their high thermal mass naturally regulates indoor temperatures and humidity, reducing the need for mechanical cooling and cutting carbon emissions,” said Dr. Ma.

Lightweight cardboard also makes it easier to reach places where moving heavy materials is tough – remote communities, outstations, island sites, or post-disaster rebuilds. The smaller transport footprint lowers costs and emissions before construction even starts.

Strength you can dial in

How strong are the finished walls? That depends on the thickness and geometry of the cardboard confinement and the compaction of the earth inside.

The team has derived a design formula that links cardboard thickness to wall capacity so engineers can size components to the loads in a low-rise building.

“We’ve created a way to figure out how the thickness of the cardboard affects the strength of the rammed earth, allowing us to measure strength based on cardboard thickness,” said Dr. Ma.

That kind of rule-of-thumb is a bridge to practice. It lets designers weigh trade-offs – thicker tubes for higher loads, lighter shells for partitions – and tune details for cost, weight, and performance.

From concept to code

There are open questions, as with any new material. Moisture protection and detailing matter for anything made from soil and paper. So do pests, fire performance, and the durability of the cardboard confinement through decades of weather.

Those are solvable with smart envelopes, plinths, and finishes, but they need testing, standards, and guidance so councils and insurers can say yes with confidence.

Even so, the direction is clear. Using what’s underfoot, confined with what normally goes in the bin, can cut embodied carbon fast and at scale – especially in single-story homes, community buildings, sheds, and schools. The fact that it’s demountable and recyclable at end-of-life is a bonus for the circular economy.

The bigger picture

The idea follows a longer line of cardboard architecture, from temporary pavilions to emergency shelters. What’s new is the leap from temporary to permanent, from demonstration to structure you can design, calculate, and permit.

If adopted widely, cardboard-confined rammed earth could become a toolkit for net-zero construction: local soils, minimal processing, light logistics, and materials that return to useful streams when buildings change.

The promise is not just lower numbers on a carbon ledger. It’s buildings that feel cool in summer, that wear with dignity, and that are made from ordinary stuff. In an era of heavy footprints, that’s a refreshing way to build light.

The study is published in the journal Structures.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates. 

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–