Behind every smooth new pavement or shimmering glass tower lies a material with a hefty climate cost. Now, Australian researchers working with lithium mine waste say they have a recipe that could start to change that picture.
Concrete’s dirty secret: 952 tonnes every second
Concrete shapes almost everything we build. Around 30 billion tonnes are produced each year worldwide. That works out at roughly 952 tonnes every second – an almost unimaginable flow of sand, gravel, water and cement.
This building boom brings a huge environmental bill. Cement, the glue that binds concrete, gets heated in giant kilns to around 1,400°C. That process burns fuel and breaks down limestone, both of which release carbon dioxide.
Concrete is responsible for about 8% of global CO₂ emissions and close to a third of all non-renewable raw materials used in construction.
As cities expand and infrastructure ages, demand for concrete keeps rising. Even with better building design, global volumes are not falling. That has turned “green concrete” from a niche research topic into a core climate challenge.
From battery waste to building blocks
Australia, one of the hotspots of lithium mining, has become an unlikely testbed for a new concrete formula. Lithium is crucial for batteries in electric cars, phones and energy storage systems. Extracting and refining it, though, produces large heaps of mineral residue.
One of those residues is a material called delithiated β‑spodumene, often shortened to DβS. In simple terms, it’s the mineral left over after lithium has been removed from spodumene ore.
Usually, DβS is treated as waste: dust, fine particles and fragments stored in tailings dams or landfills. Those piles bring long-term risks for soil and water, and they occupy large areas of land.
A new role for an ignored by‑product
A team led by Professor Aliakbar Gholampour at Flinders University asked a simple question: instead of burying DβS, could it help build our cities?
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The researchers worked with geopolymer concrete, a category of concrete that replaces traditional Portland cement with different binders. Geopolymers use industrial by‑products such as slag or fly ash and rely on chemical “activators” rather than high-temperature kilns.
Into this geopolymer mix, they added DβS as an extra ingredient.
By reusing delithiated β‑spodumene in geopolymer concrete, the researchers turned a costly waste stream into a structural material with promising strength and durability.
The idea is similar to how builders already use fly ash or blast furnace slag to tune concrete performance. DβS, with its specific mineral structure, acts as a filler and a reactive component that can change the way the binder hardens.
How the new “green” concrete behaves
Testing the mix in the lab
The Australian team prepared several geopolymer mixes. They adjusted the ratios of:
- alkaline activators (the chemicals that trigger the geopolymer reaction)
- base materials (like slag or fly ash)
- DβS content
Each formulation was cured at ambient temperature rather than in high‑heat ovens, which already reduces energy use. They then measured standard properties relevant for the construction sector.
| Property tested | Why it matters |
|---|---|
| Compressive strength | Indicates how much load a column or slab can bear before failure. |
| Durability over time | Shows how the material resists cracking, weather, and chemical attack. |
| Microstructure | Reveals how pores and crystals form, which affects long‑term performance. |
According to their published results, the most balanced formula went beyond simply “matching” standard concrete.
In some mixes, compressive strength exceeded that of typical Portland cement concretes and rivalled other advanced geopolymer mixes. The microstructure looked denser and less porous, a good sign for resistance to water and chemicals.
In the best configuration, geopolymer concrete containing DβS outperformed several conventional concretes while cutting the need for high‑emission ingredients.
Why this matters for emissions
Geopolymer concrete already offers potential CO₂ savings because it avoids part of the emissions from cement clinker – the most carbon‑heavy component. When DβS replaces fly ash or other additives, several benefits line up at once:
- Less landfill pressure: mining residues get repurposed instead of stockpiled.
- Lower raw material extraction: less natural sand and stone need to be quarried.
- Reduced reliance on coal by‑products: fly ash, which comes from coal power plants, becomes scarcer as the grid decarbonises.
- Shorter supply chains in some regions: lithium processing hubs could directly feed local concrete plants.
As lithium demand keeps rising for EVs and grid batteries, the quantity of DβS produced each year will also increase. That gives this approach a built‑in scalability, at least in mining regions.
From lab curiosity to real‑world bridges
The path from promising experiment to motorway bridge is rarely straightforward. Building codes remain conservative, and for good reason: structures must last decades without fail.
For DβS‑based geopolymer concrete to leave the lab, several hurdles remain:
- long‑term outdoor testing under real weather and loads
- fire resistance studies and structural testing of full‑scale elements
- clear standards so engineers can specify the material in projects
- economic assessment compared with traditional mixes in different markets
Despite those steps, the research lands at a convenient moment. Industries are under pressure to prove they can cut emissions without halting growth, and construction firms are searching for credible low‑carbon options that don’t sacrifice performance.
Other attempts to clean up concrete
Living, healing, and wood‑based solutions
The Australian work adds to a crowded field of concrete innovation. Around the world, researchers test a range of ideas that push the material in strange new directions.
- Bacteria-based “biocement”: powdered mixes that contain dormant bacteria, reactivated by water, urea and calcium to precipitate limestone and bind grains together.
- Self-healing capsules: tiny containers of enzymes or healing agents embedded in concrete that crack open when fissures form, slowly sealing microcracks over time.
- Wood‑derived cement additives: European projects look at turning forestry residues into reactive components that partially replace clinker in cement.
Each solution addresses a different part of the emissions puzzle: some aim at the chemical process, some target longevity so less material needs replacing, and others tackle the waste streams of other industries.
What exactly is a geopolymer?
The term “geopolymer” can sound intimidating, but the basic concept is quite intuitive.
Instead of heating limestone in a kiln to get clinker, a geopolymer mix uses aluminosilicate materials – minerals rich in aluminium and silicon – and combines them with alkaline activators, often solutions based on sodium or potassium.
Geopolymers build a three‑dimensional network of atoms at room temperature, forming a hard, stone‑like material without the high‑heat step that drives much of cement’s emissions.
Common sources for these aluminosilicates include fly ash, blast furnace slag and certain clays. DβS now joins that list as a promising candidate. The exact recipe matters a lot: tiny changes in chemistry can shift strength, setting time and durability.
Possible scenarios and real‑life uses
If DβS‑based geopolymer concrete scales up, its first targets are likely to be regions with both intensive lithium mining and strong construction demand: parts of Australia, South America or China.
In those areas, the material could first be used in:
- non‑critical elements such as pavements, low‑rise industrial slabs or retaining walls
- precast blocks and panels produced in controlled factory settings
- infrastructure close to mining operations, where supply is simplest
Once performance data accumulates, more ambitious structures—multi‑storey buildings or bridges—could follow. Insurance companies and regulators will look closely at that evolution.
The approach also hints at a broader shift: pairing every high‑impact industry, such as mining or energy, with construction techniques that absorb its by‑products. In that sense, concrete becomes not only a consumer of raw materials but a sink for waste that would otherwise linger in dumps or tailings ponds.
Risks, trade‑offs and what to watch next
Reusing industrial waste always raises legitimate questions. The chemical composition of DβS must be tightly controlled to avoid leaching of unwanted elements into soils or groundwater. Long‑term monitoring of test structures will be crucial.
Another risk lies in locking the construction sector too tightly to a single resource. If lithium extraction patterns shift, supply chains for DβS‑based concrete may face instability, just as the industry is trying to move away from dependence on coal‑derived ash.
Still, the Australian research underlines a useful principle: the green transition in transport and energy does not end with batteries and solar panels. It continues in the more prosaic realm of cement mixers, rebar and formwork, where careful chemistry can turn yesterday’s waste into tomorrow’s buildings.