Researchers at RMIT University have developed a groundbreaking material known as cardboard-confined rammed earth, which offers a sustainable alternative for construction. This innovative solution utilizes cardboard, water, and soil, making it entirely reusable and recyclable. With over 2.2 million tons of cardboard and paper discarded in Australian landfills each year, this new material presents a viable method to reduce waste while addressing environmental concerns related to traditional building methods.
The production of cement and concrete is responsible for approximately 8% of annual global emissions. Traditional rammed earth construction combines soil with cement to enhance strength. However, this new method eliminates the need for cement, providing a construction option that boasts a carbon footprint reduced to just one quarter of that of conventional concrete, and at less than one third of the cost.
Dr. Jiaming Ma, the lead author of the study, emphasized the significance of this advancement. “By simply using cardboard, soil, and water, we can make walls robust enough to support low-rise buildings,” Ma stated. He noted that the development reflects a global trend towards embracing earth-based construction methods that align with net zero goals and an interest in sustainable materials sourced locally.
Transforming Construction Practices
The process of creating cardboard-confined rammed earth can take place directly on construction sites. Builders can compact a mixture of soil and water within cardboard formwork, either manually or with machinery. This approach not only simplifies logistics but significantly reduces transport costs, as most materials can be sourced locally. Emeritus Professor Yi Min ‘Mike’ Xie, a leading expert in structural optimization, pointed out the potential for a more efficient construction industry. “Instead of hauling in tonnes of bricks, steel, and concrete, builders would only need to bring lightweight cardboard,” Xie remarked.
This sustainable method is particularly advantageous for construction in remote regions, such as parts of Australia where red soils, ideal for rammed earth construction, are abundant. Ma highlighted the benefits of rammed earth buildings in hot climates, stating, “Their high thermal mass naturally regulates indoor temperatures and humidity, reducing the need for mechanical cooling and cutting carbon emissions.”
The structural integrity of the cardboard-confined rammed earth varies based on the thickness of the cardboard tubes used. The research team has developed a formula to determine how this thickness affects the overall strength of the material. “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,” Ma explained.
In a separate study led by Ma, the combination of carbon fibre and rammed earth demonstrated comparable strength to high-performance concrete, indicating further possibilities for enhancing this innovative building material.
Future Collaborations and Research Opportunities
The team at RMIT University is eager to collaborate with various industries to promote the widespread adoption of cardboard-confined rammed earth. Companies interested in exploring partnerships can reach out to the university’s research department at [email protected].
The findings of the study titled “Cardboard-confined rammed earth towards sustainable construction,” co-authored by Ma and colleagues, are published in the journal Structures (DOI: 10.1016/j.istruc.2025.110117). Another related study, “CFRP-confined rammed earth towards high-performance earth construction,” is available in Composite Structures (DOI: 10.1016/j.compstruct.2025.119512).
This innovative approach to construction not only highlights the potential for sustainable building practices but also opens the door to more eco-friendly and cost-effective methods that could reshape the future of the industry.
