Walls built without cement sound like science fiction, yet a new material is already challenging that assumption. Engineers blend ordinary soil, water and discarded cardboard to form a low-carbon building mix. This mix aims to create solid, comfortable homes without the usual pollution and without complex machinery. It stays simple enough for everyday building sites. At the same time, its ambition questions whether traditional concrete still deserves its dominant place in construction.
From rammed earth tradition to a refined wall system
In a Melbourne laboratory, engineers from RMIT University have shaped a material known as cardboard-confined rammed earth, or CCRE. It combines compacted soil, water and recycled cardboard tubes into dense, cylindrical cores designed for low-rise buildings. Instead of complex chemistry, the system relies on pressure, geometry and careful packing.
These cardboard molds act as both formwork and permanent casing, holding the earth in place while the mix cures. Once compacted, the tubes function as a continuous wall system that can bear vertical loads and resist cracking. Builders gain a lightweight, modular solution that uses familiar tools and skills.
The main binder in concrete is responsible for nearly 8% of global CO2 emissions. The US Environmental Protection Agency reports that figure. By removing cement, CCRE walls cut the carbon footprint of similar concrete structures to one quarter. They also reduce production costs to less than one third of mixes.
How cement disappears from the construction recipe
Modern rammed earth construction usually adds a binder to satisfy strength standards. That step often cancels environmental advantages of earth walls. Lead researcher Dr Jiaming Ma explains in ScienceDaily that projects use more binder than needed. He notes that design habits have not yet caught up with what structural tests show.
In the CCRE system, engineers compact soil inside sturdy cardboard tubes that confine the material and keep it under compression. This shell stops the earth core from bulging or cracking as loads move through the wall. Because the soil already sits in thick sections, extra cement strength becomes unnecessary.
The cardboard casing and leftovers can be recycled or used again after construction is finished. Every year, more than 2.2 million tons of paper and cardboard are dumped in landfills in Australia. Case Studies in Construction Materials highlight the economic and environmental benefits of directing a portion of that stream toward CCRE.
Thermal comfort, climate resilience and everyday building impacts
The research team sees CCRE thriving in hot, resource-limited regions where energy-intensive materials are hard to transport or afford. Because the mix uses local soil and recycled packaging, communities stay less dependent on long supply chains. Builders can adjust the recipe to available soils while still meeting key performance targets.
CCRE can be produced directly on site by compacting a soil and water mix inside recycled cardboard molds. Crews work manually or with low-power equipment. This keeps construction feasible in remote areas with weak infrastructure. Projects serving housing needs during climate stress then rely less on imported materials and specialized factories.
Rammed earth is known for high thermal mass, which slows indoor temperature swings and stabilizes humidity. Dr Jiaming Ma notes that these buildings stay comfortable in hot climates with much less mechanical cooling. When designers remove cement yet keep this performance, they cut embodied emissions and long-term energy use.
Design choices that match or exceed cement-based concrete performance
Material strength in CCRE walls depends on the thickness and properties of the cardboard tubes that surround compacted soil. Engineers vary tube dimensions and soil composition, then model how each combination carries vertical loads and resists deformation. This flexibility gives designers options instead of one fixed specification.
For projects that demand higher performance, the team has tested versions reinforced with carbon fiber embedded in the earth matrix. Early results show strength levels comparable to advanced concrete mixes while still relying on simple ingredients. This opens possibilities for structures that carry heavier loads without reverting to conventional binders.
According to the RMIT research repository, the group is seeking industrial partners to pilot CCRE on real projects. As scrutiny of construction emissions grows, governments and developers look for practical options. A system that replaces cement while using familiar methods has a strong chance to move from lab to market.
Low-tech alternatives in a wider sustainable building landscape
CCRE aligns with a wider move toward nature-based building materials that cut emissions while remaining practical. Researchers and designers test hempcrete, mycelium composites and other bio-based systems that challenge concrete’s dominance. These approaches use different ingredients yet share the ambition to reshape how structures relate to climate and resources.
Unlike more speculative innovations, CCRE does not depend on rare minerals, complex reactors or proprietary chemistry. Its ingredients are soil, water and waste cardboard that appear on ordinary building sites around the world. Teams can learn the technique quickly, then adapt it to local regulations, labor skills and housing priorities.
That simplicity matters for homes, schools and clinics, where budgets and timelines are tight. When builders replace cement with local soil and recycled packaging, they free money and energy for other needs. Dirt, water and waste then become tools for a construction model that respects climate limits.
What this soil and cardboard breakthrough suggests for tomorrow
CCRE hints that the future of construction may rely less on heavy industry and more on local resources. It combines soil, water and recycled cardboard into a realistic way to shrink emissions without waiting for distant technologies. If regulations, finance and training improve together, everyday projects could treat cement as an option, not a default. They would still deliver strong, comfortable buildings that answer the needs of a warming world.
