What if I told you that the future of sustainable building might just consist of three simple ingredients: earth, water and cardboard? It sounds almost too simple to be true, but researchers at RMIT University in Australia have just made it a reality with their groundbreaking material called Cardboard-Confined Stamped Earth, or CCRE.
Here's the thing. We all know that concrete is found everywhere in our built environment, but it comes with a high environmental cost. Cement and concrete production is responsible for around 8% of annual global emissions. At the same time, Australia alone sends over 2.2 million tonnes of cardboard and paper to landfill each year. The RMIT team looked at these two problems and saw an opportunity to solve both at the same time.
Designer name: RMIT University
The concept is brilliantly simple. Instead of using traditional formwork that is removed after the concrete has hardened, builders use cardboard tubes as permanent formwork. They compact moistened soil into these tubes, and the cardboard stays in place, continually enclosing and strengthening the soil core. Think of it like a structural hug that never lets go. The exciting thing about it is how sustainable it really is. Dr. Jiaming Ma, the project's lead researcher, explains that in modern rammed earth structures, cement is usually added to the soil to give it extra strength. But for these naturally thick rammed earth walls, this cement is actually overkill. By swapping cement for cardboard, the team created a material with just a quarter of the carbon footprint of concrete and less than a third of the cost. Breaking the numbers down, a full-size CCRE column produces just 17.41 kilograms of carbon dioxide equivalent, compared to 77.95 kilograms for normal Concrete.
The process itself is remarkably accessible. Construction crews can make CCRE on site by compacting the soil and water mixture into cardboard tubes, either by hand or with machines. Professor Yi Min “Mike” Xie points out that instead of hauling in tons of brick, steel and concrete, builders only need to bring lightweight cardboard since almost all of the material can be sourced locally. This is particularly groundbreaking for remote areas where red soils ideal for rammed earth construction are readily available.
Now you might be wondering about the strength. After all, cardboard doesn’t exactly scream “structural integrity.” But here's where things get interesting. The team developed a formula that allows them to accurately predict how strong the material will be based on the thickness of the cardboard tubes. After 28 days of drying, compression tests showed that CCRE has comparable strength to traditional cement-stabilized rammed earth. Although it is not quite as strong as typical concrete, it is more than sufficient for structural applications in low-rise buildings. There is another nice benefit of the. Rammed earth construction that isn't talked about enough. Thanks to their high thermal mass, these buildings naturally regulate internal temperature and humidity, making them ideal for hot climates. Less mechanical cooling means that both energy consumption and CO2 emissions are reduced even further.
The RMIT team envisions CCRE being perfect for low-rise, community and off-grid projects. It taps into a global resurgence in earth-based construction, driven by net zero targets and a growing interest in local, sustainable materials. By converting waste into structure, this innovation shows us that sustainable building materials can be simultaneously greener, cheaper and easier to produce. The team is now looking for industry partners to help scale this material for widespread use. It's a refreshingly simple solution to a complex problem, and proves that sometimes the best innovations come from looking at old techniques from a new, sustainable perspective.
