There is a material behind every smooth new road or shiny glass tower that has a big impact on the environment. Now, Australian scientists who are working with lithium mine waste say they have a plan that could start to change that.
Concrete’s dirty secret: 952 tons every second
Almost everything we build is made of concrete. Every year, about 30 billion tons are made around the world. That’s about 952 tons every second, which is an almost unimaginable amount of sand, gravel, water, and cement.
This building boom has a huge cost to the environment. Cement, which holds concrete together, is heated to about 1,400°C in huge kilns. That process burns fuel and breaks down limestone, both of which give off carbon dioxide.
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Concrete is responsible for about 8% of all the CO₂ that is released into the air and almost a third of all the raw materials that are not renewable that are used in construction.
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Concrete demand keeps going up as cities grow and infrastructure gets older. The amount of buildings around the world is not going down, even though they are being built better. That has made “green concrete” a major climate problem instead of just a small area of study.
From trash from batteries to building blocks
Australia, which is known for its lithium mining, is now an unlikely place to test a new concrete formula. Lithium is very important for batteries in electric cars, phones, and systems that store energy. But when you extract and refine it, you get a lot of mineral waste.
Delithiated β-spodumene, or DβS for short, is one of those residues. It’s the mineral that is left over after lithium has been taken out of spodumene ore.
People usually throw away DβS, which is dust, small particles, and pieces of rock that are stored in tailings dams or landfills. These piles take up a lot of land and pose long-term risks to soil and water.
A new job for a by-product that was ignored
A group of researchers at Flinders University, led by Professor Aliakbar Gholampour, asked a simple question: could DβS help build our cities instead of burying it?
The researchers used geopolymer concrete, which is a type of concrete that uses different binders instead of regular Portland cement. Geopolymers use industrial waste like slag or fly ash and rely on chemical “activators” instead of high-temperature kilns.
They added DβS to this mix of geopolymer.
The researchers turned a waste stream that was expensive to get rid of into a structural material with good strength and durability by using delithiated β-spodumene again in geopolymer concrete.
This idea is similar to how builders already use fly ash or blast furnace slag to improve how concrete works. DβS is a reactive mineral that can change how the binder hardens and acts as a filler.
What happens when you use the new “green” concrete
Testing the mix in the lab
The Australian team made a number of geopolymer mixes. They changed the ratios of:
alkaline activators (the chemicals that start the geopolymer reaction)
basic materials, such as fly ash or slag
DβS amount
Instead of being baked in high-heat ovens, each formulation was cured at room temperature. This already cuts down on energy use. Then they measured standard properties that are important for the construction industry.
Tested property Why it matters
Strength of compression Shows how much weight a column or slab can hold before it breaks.
Lasts a long time Shows how the material holds up against cracking, weather, and chemicals.
Microstructure Shows how pores and crystals form, which has an effect on long-term performance.
The most balanced formula, according to their published results, did more than just “match” standard concrete.
In some mixes, the compressive strength was higher than that of regular Portland cement concretes and was similar to that of other advanced geopolymer mixes. The microstructure looked more solid and less porous, which is a good sign that it will hold up to water and chemicals.
In the best setup, geopolymer concrete with DβS did better than a few regular concretes and didn’t need any high-emission materials.
Why this is important for emissions
Geopolymer concrete can already help save CO₂ because it doesn’t release as much CO₂ as cement clinker, which is the most carbon-heavy part of concrete. When DβS takes the place of fly ash or other additives, a number of benefits happen at the same time:
Less pressure on landfills: instead of being thrown away, mining waste is used again.
Less digging for raw materials means less natural sand and stone need to be dug up.
Less dependence on coal by-products: fly ash, which comes from coal power plants, is becoming less common as the grid becomes less carbon-intensive.
Some areas have shorter supply chains, so lithium processing hubs could send lithium directly to local concrete plants.
The amount of DβS made each year will also go up as the demand for lithium for electric vehicles and grid batteries grows. At least in mining areas, this method has built-in scalability.
From lab interest to real bridges
It’s not always easy to go from a promising experiment to a motorway bridge. Building codes are still strict, and that’s a good thing because buildings need to last for decades without fail.
There are still some problems that need to be solved before DβS-based geopolymer concrete can leave the lab:
long-term testing outside in real weather and with real loads
studies of fire resistance and tests of full-scale structural elements
clear guidelines so that engineers can choose the right material for their projects; an economic comparison of different mixes in different markets
Even with those steps, the research comes at a good time. Industries are under pressure to show that they can cut emissions without slowing down growth. Construction companies are looking for credible low-carbon options that don’t hurt performance.
Other ways to clean up concrete
Living, healing, and solutions made from wood
The Australian work is one of many new ideas in concrete. Researchers all over the world are testing a lot of different ideas that take the material in strange new directions.
Biocement made from bacteria is a powdered mix that contains dormant bacteria. When it comes into contact with water, urea, and calcium, it forms limestone and binds grains together.
Self-healing capsules are small containers of enzymes or healing agents that are built into concrete. When cracks form, the capsules break open and slowly seal the microcracks over time.
Wood-derived cement additives: European projects are looking into how to turn waste from the forestry industry into reactive parts that can partially replace clinker in cement.
Some solutions focus on the chemical process, some on making things last longer so less material needs to be replaced, and others on the waste streams of other industries.
What is a geopolymer, exactly?
The word “geopolymer” may sound scary, but the basic idea is pretty simple.
A geopolymer mix uses aluminosilicate materials, which are minerals that are high in aluminum and silicon, and mixes them with alkaline activators, which are usually solutions based on sodium or potassium. This is different from heating limestone in a kiln to get clinker.
Geopolymers create a three-dimensional network of atoms at room temperature, making a hard, stone-like substance without the high-heat step that causes a lot of cement’s emissions.
Fly ash, blast furnace slag, and some clays are common places where these aluminosilicates come from. DβS is now on that list as a good candidate. The exact recipe is very important because even small changes in chemistry can change strength, setting time, and durability.
Possible situations and uses in real life
If DβS-based geopolymer concrete becomes more popular, it will probably first be used in places where there is a lot of lithium mining and a lot of construction going on, like parts of Australia, South America, or China.
The material could first be used in those places for:
Precast blocks and panels made in controlled factory settings for non-critical things like pavements, low-rise industrial slabs, and retaining walls. Infrastructure near mining operations, where supply is easiest.
When enough performance data is collected, more ambitious structures, like bridges or buildings with more than one floor, could come next. That change will be closely watched by insurance companies and regulators.
The approach also suggests a bigger change: linking every high-impact industry, like mining or energy, with building methods that use up its waste. In this way, concrete not only uses up raw materials, but it also gets rid of trash that would otherwise sit in dumps or tailings ponds.
What to watch next, risks, and trade-offs
It’s always a good idea to ask questions about using industrial waste again. To keep unwanted elements from leaching into soils or groundwater, the chemical makeup of DβS must be carefully controlled. It will be very important to keep an eye on test structures for a long time.
Another danger is tying the construction industry too closely to one resource. If the way lithium is mined changes, the supply chains for DβS-based concrete may become unstable. This is happening at the same time that the industry is trying to stop relying on coal-derived ash.
The Australian study does, however, show a useful point: the green transition in energy and transportation doesn’t stop with batteries and solar panels. It goes on in the more everyday world of cement mixers, rebar, and formwork, where careful chemistry can turn yesterday’s trash into buildings for the future.
