The role of concrete infrastructure is strategic to any economy. It comes in a variety of forms, such as buildings, bridges, tunnels, and ports, and given such significance to our society their resilience is important.
It is well-known that the deterioration rate not only depends on material compositions and construction processes, but also relies on the on-going climatic environment during the service phase of the structures’ lifecycle. Climate change, however, will have an increasing impact on our infrastructure through precipitation, carbon dioxide levels, higher sea levels and higher temperatures.
The rise of CO2e and GHGs in recent decades have begun to change our surrounding environment, making it more aggressive and causing acceleration of the deterioration processes, such as acid rain and carbonation, causing corrosion-induced cracking and spalling. This results in more costly and disruptive repairs, as well as integrity loss of concrete structures.
Carbonation is not usually a big issue for the UK as it occurs slowly through the cover concrete to reinforcement steel, but up until the mid-80’s that was based on concrete exposed to <350ppm CO2. Levels are currently over 400ppm and rising, causing carbonation to worsen. Corrosion of steel will continue to pose a huge problem as a consequence with the rapid increase of climate change.
The good news is that there are innovative methods available for corrosion protection and monitoring of the built environment that can be retrofitted to existing structures as they age or built in from new as the structure is formed.
Repurposed industrial wastes are used to create a smart alkali-activated cementitious material (AACM geopolymer) which is used as both a cement repair binder and impressed current cathodic protection (ICCP) anode which protects the embedded steel in concrete structures.
LoCem, an AACM geopolymer, offers low carbon sustainability due its production using little to no energy from waste streams derived from fossil fuels, steel, and mining. This results in 90% less CO2 emissions compared to CEM I production, which is already a huge contributor to climate change.
LoCem can form as a mortar, grout or concrete conventionally placed by cast in-place or cut and grouted into decks for existing reinforced concrete structure (multi-storey car parks for example), as well as gunned into joints for transitional steel frame heritage buildings.
This combination of decarbonised concrete repair and cathodic protection provides long-term resilience to existing structures. Control of corrosion and protection of the steel retains vital embodied carbon and lengthens the structure’s service life over decades, reducing the need for complete demolition or replacement of the structure.
For new buildings, urbanisation and population growth has increased new construction significantly in the last few decades, and if it continues at this rate, it will stand in the way of the UK delivering on the Paris agreement commitments of limiting global warming to well below 2°C. Therefore, the industry should be looking at how to sustainably build new infrastructure which can endure the damaging effects of climate change.
LoCem has recently been developed to form a factory made, moulded ICCP component that is placed on the steel rebar in-situ or before the concrete is poured of new structures. The component is called the LoCem Modular Anode Unit (MAU) and is installed as a “plug-and-play” system with tailored current densities, helping to provide long-term sustainable, structural resilience and control over structural corrosion indefinitely. This offers an important route to protecting embodied carbon of structures.
Ramboll found in their new report that on average 600 tonnes of CO2e embodied carbon is emitted for a newly constructed building of 1000 m2 throughout its lifecycle. Implementation of the MAU provides a low carbon sustainable solution to help retain embodied carbon within new infrastructure, as the future protection against corrosion is partnered with monitoring from embedded corrosion rate probes. This informs on performance and reduces the chance of future disruption by remotely controlling corrosion, helping to retain the remaining embodied carbon.
Technology and innovation will have a key role to play in addressing the challenges of climate change and what affect this has on existing and new infrastructure. The combination of low carbon build materials and cathodic protection prove that there are means to reduce the disruptive effect of rust and corrosion, and that the existing steel we utilise within infrastructure can be effectively protected.
Innovations such as the LoCem MAU also shows there is an accessible way for the sector to adapt new construction methods and provide resilience from the earliest stages. Implementing technology like cathodic protection anodes that can also be used as sustainable build materials will help to achieve Net Zero goals futureproofing new and existing infrastructure against climate change effects for its whole life.