Concrete is a wonderful material, but it comes with a heavy carbon footprint.
The Portland cement component accounts for between five and eight per cent of global industrial greenhouse emissions. Each tonne of Portland cement generates its own weight in CO2 in the production process, along with smaller amounts of other, more damaging, greenhouse gases such as methane, mono-nitrogen oxides and fluorine.
These days, the greenhouse emissions from standard concrete production come at both an environmental and monetary cost. But an emerging group of building materials — geopolymers — has the potential to transform the building industry, dramatically reducing not only its greenhouse costs, but capital and maintenance costs as well.
Described as ‘the new material for the Third Millennium’, they are mouldable, ceramic-like inorganic polymers that produce a hard, chemically stable, low shrinkage material, with very high early age strengths. They can be quickly set at high temperature (70ºC) and can be produced using conventional concrete-manufacturing equipment.
The CSIRO has developed an alumino-silicate geopolymer system which offers significant environmental benefits over Portland cement. For every tonne manufactured, geopolymer concrete uses 27 per cent less embodied energy, produces only half the carbon emissions and lessens the impact on the environment by 22 per cent compared with an equivalent Portland cement product.
Geopolymer products also offer improved material properties, including greater resistance to impact and acids. They are strong but lightweight, and can withstand fire and blasts. Additionally, they can be cast, sprayed, extruded and used as an adhesive.
Building materials based on geopolymers cost roughly the same as existing materials, but provide major technical benefits. Using geopolymers in industrial flooring, pipes or coatings can reduce wear caused by industrial spills or soil acidity. This not only improves long-term performance and durability and reduces capital and/or maintenance costs, it may also lower insurance premiums.
CSIRO’s geopolymer system uses industrial by-product materials such as flyash from coal-fired power stations, mineral-processing slags and mining wastes, as the primary feedstock. The engineering design flexibility and construction efficiency means the geopolymer system has wide-ranging potential applications.
Because they are derived from natural minerals, geopolymers can be readily converted to recycled aggregate for use as road base or aggregates for premix and precast concrete production.
In partnership with a number of companies, CSIRO’s geopolymer technology has been developed for various applications including:
- acid resistant sewer pipes;
- high-performance railway sleepers;
- fire-resistant poles, walling and flooring panels;
- lightweight, impact-resistant roof tiles;
- storage tanks;
- fire-resistant textiles; and
- synthetic nano-filler materials with improved manufacturing capability.
Other potential uses include adhesives, coatings, composites, conduits, insulation, marine structures, refractories, soil stabilisation and waste encapsulation.
For further information visit www.csiro.au/science/Geopolymers-Overview