Cardboard, soil and water. That’s the recipe behind a new Australian building material that’s turning heads across the industry.
Australia needs to build more homes. Making those homes out of a material that's cheaper, greener, and easier to transport to site could be a game-changer. Image: Getty
With about one-quarter of concrete’s embodied carbon and roughly 60% lower material costs, a new material for home building has construction experts excited.
Developed at RMIT University and known as cardboard-confined rammed earth (CCRE), it’s a practical, deceptively simple idea with real potential to reset how we deliver homes, especially where transport and speed make or break a project.
“It’s the first of its kind – combining cardboard and rammed earth into a new building material,” says lead researcher Dr Jiaming Ma, from RMIT’s School of Engineering.
“We can see this new construction material bringing a lot of opportunities in the future, considering its low cost and ultra-low carbon emissions.”
Why it’s (very) green
Modern rammed earth typically uses cement for stabilisation and cement is a major source of global emissions (often cited around 8%). CCRE takes a different route: replacing cement with a 4-millimetre cardboard tube as a permanent shell, confining and strengthening a compacted soil core.
RMIT’s tests showed performance comparable to cement-stabilised rammed earth, opening the door to residential use without the carbon cost of cement.
“A lot of luxury houses in Australia are already built with rammed earth stabilised by cement,” Dr Ma said. “We’ve proved our new material can achieve the same strength, so we naturally see opportunity for it in residential housing.”
A cardboard-confined rammed earth column and a carbon fibre reinforced polymer-confined rammed earth column. Image: RMIT
Low-carbon, low-cost, and readily available
The appeal for builders is as practical as it is planetary. Instead of hauling in tonnes of bricks, steel or concrete, up to 90% of CCRE wall’s volume can be sourced from excavation on site, sharply reducing transport, emissions and cost.
RMIT’s life-cycle analysis indicates material costs about 60% lower than concrete, with no energy-intensive firing as with bricks. With builders only needing to transport lightweight cardboard, the simplicity makes CCRE a natural fit for remote and regional projects.
And with cardboard waste already a major issue nationwide – more than 2.2 million tonnes sent to landfill in Australia each year – the method also offers a scalable recycling pathway.
Comfort by nature
Beyond the numbers, earth walls are renowned for acoustic performance and thermal mass – qualities that help steady indoor temperatures and humidity, easing reliance on mechanical cooling. That’s a compelling value-add for regional and northern Australia, where red soils are plentiful and climate control is a major cost.
“People call it low-tech,” Dr Ma said, “but we want to use the latest technologies to reshape it as a promising sustainable material for the future.”
Industry curiosity
Momentum is building beyond the lab. Andrew Hamilton, managing director at Euca Built – which partners with builders and modular factories to deliver sustainable small homes and cabins across regional Victoria – says access is the big opportunity.
“A major challenge with regional projects is getting good materials to remote sites. CCRE presents a really exciting chance to make that process not only easier, but much more sustainable too," Mr Hamilton said.
In South Australia, Jackson Digney, director at Enduro Builders, sees real promise if moisture is robustly managed. “Cardboard can host mould and, depending on its make-up, lose structural integrity,” he said.
“In our sustainability and energy-efficient bubble, appetite from homeowners and councils is huge for lower-carbon, locally sourced materials, but for CCRE to gain traction, builders will want tested proof of longevity, structural performance and, most crucially, building health.”
The RMIT team says those concerns are front of mind. The cardboard shell can be factory-treated with water-resistant coatings or wax before it reaches site to extend service life, and upcoming full-scale prototypes are designed to generate the durability data builders and councils will look for.
If that testing delivers, the timing is favourable: high concrete costs and tightening embodied-carbon targets are already nudging the market toward local-material, lower-transport systems – paving the way for smarter formwork and faster builds.
The RMIT-based research team. L–R: Hongru Zhang, Jiaming Ma, Dilan Robert and Ngoc San Ha. Image: RMIT
Design freedom and speed
Looking ahead, Dr Ma’s group is exploring the origami technique to develop flat-pack cardboard formwork that’s easy to transport and store, then quick to assemble on site – offering more design freedom while cutting logistics and setup time.
Automation is also on the roadmap: Dr Ma confirms the team is planning robotic compaction to handle most of the build, boosting speed and consistency while reducing labour costs.
Build partners wanted
For now, CCRE is still in testing. “Time to market depends on funding to support further research,” Dr Ma said. Full-scale wall prototypes are planned within the next two years, and the team is seeking home-building partners for pilot projects.
Elegant in its simplicity yet potentially transformative, CCRE has the makings of a game-changer for Australian residential building – the kind of twist on an old technique that could quietly reset how we deliver the next generation of homes.
Are you interested in learning more about Australian home building? Check out our dedicated New Homes section.
English (US) · 