Behind every tower block, motorway and warehouse sits a quiet climate heavyweight: concrete. As demand for electric cars sends lithium mining surging, Australian researchers think they’ve found a way to turn one industry’s waste into another’s low‑carbon workhorse.
Concrete: the invisible giant of global emissions
Concrete feels mundane, yet the numbers are anything but. The world pours around 30 billion tonnes of it every year. That works out at roughly 952 tonnes every second, day and night.
Conventional concrete relies on Portland cement, a binder made by heating limestone and other minerals in giant kilns. That process burns large amounts of fuel and releases carbon dioxide from the limestone itself.
Concrete is responsible for around 8% of global CO₂ emissions and roughly a third of all non‑renewable materials used in construction.
Every new road and tower locks in more emissions. Governments are trying to cut back, but the demand for housing, infrastructure and data centres keeps rising. The concrete industry is under pressure to change its recipe fast, without compromising strength or safety.
An Australian idea: turn lithium waste into “green” concrete
On the other side of the climate ledger, the energy transition is fuelling a boom in lithium mining. This soft, silvery metal powers the batteries inside electric vehicles, laptops and grid‑scale storage.
Refining lithium ore leaves behind a stubborn by‑product: delithiated β‑spodumene, often shortened to DβS. It looks like dust and crushed rock. Most of it ends up stockpiled or buried near mines.
A team led by Professor Aliakbar Gholampour at Flinders University in Australia has asked a simple question: what if this battery waste could strengthen an entirely different industry?
What is DβS and why does it matter?
Spodumene is a lithium‑bearing mineral. During processing, much of the lithium is removed, leaving the delithiated form. From a miner’s point of view, that residue has little value.
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Researchers found that delithiated β‑spodumene can act as a functional ingredient in a type of low‑carbon concrete known as geopolymer concrete.
Instead of shipping DβS to landfills, the Flinders team fed it into geopolymer mixes, where it behaves a bit like a specialised filler or additive. The goal: improve performance, cut waste and reduce reliance on more polluting ingredients.
How geopolymer concrete differs from the classic mix
Geopolymer concrete does not use Portland cement as its main binder. Instead, it relies on aluminosilicate materials – rich in aluminium and silicon – that react with alkaline solutions to form a solid, stone‑like network.
Traditional geopolymer recipes often use fly ash from coal plants or blast furnace slag from steelmaking. Those materials come with their own environmental baggage and, as coal plants close, fly ash supplies are starting to tighten.
The Australian study looked at what happens when DβS partially replaces these conventional ingredients.
- Different ratios of alkaline “activators” were tested to trigger the chemical reactions.
- Mixtures were cured at room temperature instead of in energy‑intensive ovens.
- Mechanical strength and durability were measured over time.
The performance results: not just “good enough”
Some of the lab formulas did more than simply work. In optimal configurations, the DβS‑based geopolymer concrete matched or outperformed standard concretes and many existing geopolymer mixes.
Tests showed higher mechanical strength and promising long‑term durability, with potential to replace fly ash and other polluting additives.
This matters because engineers are conservative for good reason. Any low‑carbon substitute must hit strict benchmarks on compression strength, cracking, chemical resistance and long‑term stability.
Early signs suggest DβS can help on several of those fronts, particularly when used alongside other aluminosilicate sources in a carefully tuned recipe.
A push toward circular economy construction
The idea taps into a broader industrial trend: circularity. Instead of treating by‑products as useless waste, industries try to plug them into other value chains.
The potential wins from using DβS in concrete stack up on several levels:
- Less landfill waste: mining residues gain a second life instead of accumulating in tailings or dumps.
- Lower contamination risks: properly bound inside concrete, the material is less likely to leach into soil or water.
- Reduced demand for virgin resources: every tonne of DβS that works in concrete can offset part of the sand, clinker or fly ash needed.
- Climate benefits: geopolymer binders typically emit less CO₂ than classic Portland cement, especially when they use waste streams.
As the global lithium supply chain expands – from Australia and Chile to new projects in Europe – the volume of DβS will grow as well. That makes it a potentially abundant feedstock if standards and logistics fall into place.
Where this “green” concrete could be used
In the short term, researchers see clear potential for non‑critical structures, such as:
- pavements and pedestrian walkways
- low‑rise buildings and warehouses
- retaining walls and noise barriers along roads
- non‑structural precast blocks and panels
With more testing, codes could gradually open the door to bridges, high‑rise cores and infrastructure that faces harsher loads or aggressive environments.
Other attempts to clean up concrete
This project sits alongside a growing list of efforts to slash the footprint of the world’s favourite building material.
Researchers across Europe, Asia and North America are experimenting with unusual ingredients and strategies, for example:
- a “bio‑cement” powder seeded with dried bacteria that wake up with water, urea and calcium, then produce a mineral binder;
- self‑healing concrete that seals cracks using enzyme‑filled capsules, echoing the way bones repair themselves;
- projects such as Rewofuel, which look at turning wood residues into cement additives that partially replace clinker, the carbon‑intensive heart of Portland cement.
None of these ideas alone will fix construction’s climate burden, yet together they point to a more modular, flexible approach: many smaller tweaks rather than one silver bullet.
From lab bench to building site: the road ahead
Promising lab results often stumble when they reach the building site. DβS‑based geopolymers will face a familiar gauntlet:
| Challenge | Why it matters |
|---|---|
| Standardisation | Engineers and regulators need consistent data and norms before approving new mixes. |
| Supply logistics | DβS has to reach concrete plants in predictable quality and quantities. |
| Cost | Contractors will only switch if total costs stay competitive over a project’s life. |
| Public perception | Clients must trust that “waste‑based” concrete is safe and durable. |
One possible path is to start near lithium mines themselves. Local infrastructure for new battery plants, roads and housing could use DβS‑based mixes first, shortening supply chains and building a performance track record.
Key concepts behind this new concrete
Two technical ideas sit at the heart of the Australian work: geopolymers and phase evolution.
A geopolymer forms when aluminosilicate powders react with alkaline activators, rearranging into a rigid, three‑dimensional framework. Unlike Portland cement, which relies on calcium‑rich gels, geopolymers can function with much lower limestone input.
Phase evolution describes how the internal structure changes as the material cures. The Flinders team tracked how DβS particles interacted with other ingredients at room temperature, and which crystal phases formed over time. Those details control properties like strength, shrinkage and chemical resistance.
By understanding how DβS reshapes the internal microstructure, engineers can tailor mixes for specific climates, loads and lifespans.
What this could mean for future cities
If concepts like DβS‑based geopolymers scale up, tomorrow’s urban landscapes could carry a quieter climate story. A motorway viaduct might lock in waste from battery refining. A school extension could contain residues from a regional lithium project.
For architects and planners, this opens up new ways to cut embodied carbon, the emissions baked into materials before a building even opens. Combined with low‑energy design and renewable power, cleaner concrete recipes could shift construction from a major emitter to a sector that actively absorbs other industries’ leftovers.
The stakes will only grow as lithium demand rises with electric cars and grid storage. Each new mine brings environmental questions. Giving part of its waste a durable, structurally useful second life in concrete does not erase the impact, but it nudges two heavy industries in a more aligned direction.