Bridges are some of the most ambitious and expensive infrastructure projects in the world — and they have a sizable carbon footprint to match.
For the last ten years, I’ve led a team to develop a new maintenance and construction material which makes them safer, longer-lasting and more sustainable.
We’ve also standardised the training of government bridge engineers and inspectors, and created unique software to help them carry out their vital work.
The problem with concrete
After water, concrete is the most consumed resource in the world.
The manufacture of its key ingredient, ordinary Portland cement (OPC), is responsible for 10% of global carbon emissions. To put this in context, if the cement industry were a country, it would be the third biggest emitter of carbon dioxide in the world.
Once in place, concrete shrinks, cracks, and needs regular repairs. It’s also porous, so chlorides from substances like road salt can move through it and corrode steel reinforcements.
Maintaining concrete structures like bridges has often relied on the application of more concrete. To put a stop to this vicious cycle, we looked for a more sustainable alternative.
A non-cement solution
With funding from the European Commission and industry, we built on existing research to develop a brand new material. Crucially, we then took it out of the laboratory and into industry, by licensing the material for commercial use.
Our alkali-activated concrete material (AACM) or geopolymer is made from sustainable industrial waste materials. It reduces carbon emissions by 70% compared to ordinary OPC solutions.
As the AACM binds to deteriorated concrete, we can use it to mend existing concrete structures. It is resistant to fire, cracking and corrosion, so the repair lasts far longer.
We’ve also found an application for the material in a process called cathodic protection. This involves using an AACM-coated anode which creates a current to migrate corrosion away from steel reinforcement.
Aside from maintenance, AACM can also be used as a construction material in itself. Buildings around the world are using fire-resistant AACM lintels for safety, which don’t require the same fireproof coating as their concrete equivalents.
Whatever the application, the material extends service life and helps organisations avoid demolitions.