When one building ingredient shapes skylines and also heats the planet, every new idea suddenly matters. Our homes, schools, and roads rely on a binder that hides a heavy climate bill, while huge piles of packaging waste go straight to the bin. Between these two problems, researchers are testing a simple but bold alternative to cement, built from soil, water, and discarded cardboard turned into structure.
Why replacing cement has become urgent
Around the world, modern construction depends on concrete and its familiar gray binder. According to several studies, the industry is one of the biggest individual industrial polluters in the world, accounting for between 7 and 8% of global carbon dioxide emissions.
Furthermore, every year, millions of tonnes of paper and cardboard are either recycled into energy recovery facilities or dumped in landfills. Millions of tonnes of material are wasted annually in nations like Australia, even though the material still has value and could continue in a circular cycle instead of becoming trash.
Researchers saw a link between these two issues. If construction could reduce its use of cement while also absorbing part of this cardboard waste, the climate benefit would be doubled. That idea pushed a team at RMIT University to test new building elements made from ordinary soil, water, and recycled tubes instead of the usual heavy binder.
Rammed earth and smart tubes reshape construction
To move from theory to real walls and columns, the RMIT group started with rammed earth. This age-old technique compacts slightly damp soil layer by layer until it forms a dense, solid core. Many traditional houses built this way hold a steady indoor temperature, staying cooler in summer and warmer in winter without much extra energy for heating or air conditioning.
Earth is abundant and usually available close to the building site, so it avoids the polluting industrial steps needed for producing modern binders. Left on its own, though, this material can crack or crumble when it bears too much weight or when weather cycles repeat year after year. That weakness long pushed architects toward concrete and away from older building traditions.
The team decided to treat the soil core almost like a person given a protective jacket. By compacting rammed earth inside strong tubes, they stop it from bulging outward and splitting under pressure. In this configuration, the soil becomes a structural material that does not need cement, yet still reaches the strength levels required for low-rise buildings and key load-bearing elements.
Cardboard tubes give waste a structural second life
The first option focuses on small structures such as single-storey homes, community buildings, or partitions. Here, builders use compacted soil and water poured into recycled cardboard tubes. Once the mix is compressed, the cardboard no longer acts only as temporary formwork. It becomes both the mold and the permanent shell, giving shape and strength at the same time.
Tests show that these columns stand up well compared with rammed earth that relies on industrial binder mixes. By locking soil and fibers together, the tube greatly improves stability and resistance under load and during repeated stress cycles. The material’s mechanical performance depends on the thickness and quality of the cardboard, which engineers can adjust according to the project’s needs.
The climate impact is where the change becomes striking. Early measurements suggest that cardboard-confined rammed earth can cut the carbon footprint of construction to about a quarter of typical cement-based concrete, while also costing less than one third in some scenarios. Because nearly all the soil can come from the site itself, transport emissions also fall sharply.
Carbon fiber, earthquakes, and performance beyond cement
The second material uses a different jacket around the soil: carbon fiber tubes rather than cardboard. Carbon fiber is already common in airplanes, racing cars, and high-end sporting equipment because it is both very light and extremely strong in tension. Wrapped around a compacted earth core, it creates a structural element that behaves more like an advanced composite than a simple soil column.
In laboratory tests, these carbon-wrapped columns reached strengths close to high-performance concrete that relies on the usual gray binder. At the same time, they weighed much less, which reduces the loads transferred down through the rest of the structure and its foundations. That combination of low weight and high resistance makes them attractive for regions where earthquakes or unstable ground are serious concerns.
This option is more expensive than recycled cardboard and will not suit every project. However, it still eliminates the direct emissions linked to firing kilns for cement. And it keeps the benefits of rammed earth’s thermal mass. For buildings where safety margins must be higher, carbon fiber offers a way to push performance. It does so without returning to fully conventional materials with heavier footprints.
Costs, limits, and what still needs to be tested
Both systems rely on simple ingredients, yet they raise practical questions that engineers now need to answer. How will cardboard-confined walls age when exposed to moisture, insects, or accidental impacts over several decades? How will carbon fiber shells behave under fire, extreme heat, or repeated small quakes that gradually weaken ordinary structures? Long-term tests must still provide those real-world answers.
Regulation also matters. Building codes in many countries were written around steel, bricks, conventional concrete, and standard cement products. Approving new materials takes time, full-scale trials, and a clear path for certification so that insurers and public authorities feel confident. Pilot projects, especially in low-rise or temporary buildings, could help create that missing track record and show how these columns behave outside the laboratory.
Finally, these rammed earth solutions will likely sit alongside other climate tools rather than replace them entirely. The global construction sector is also experimenting with lower-carbon binders, recycled aggregates, and carbon capture at existing plants. Combining those strategies with soil-and-cardboard elements can spread the effort and reduce dependence on any single high-emission technology.
A new path for builders who want lighter, cleaner structures
Early results already suggest that these simple columns made from earth, water, and recycled tubes could shift building habits. They offer an alternative to today’s dominant cement. By treating soil as a valuable structural core and cardboard as more than disposable packaging, the research reuses familiar materials. This approach opens a practical route to lower-carbon, locally sourced buildings. If long-term tests confirm durability and codes evolve, tomorrow’s houses may stand on familiar-looking foundations. They would carry a far smaller and less visible climate bill.
