Concrete is a common fixture in the building blocks of everyday life. Image: US Navy@Wikimedia Commons
Concrete is the most widely used construction material in the world, with use dating back to Ancient Egypt.
Predictably, our needs concerning construction and the environment have changed since then, but the abundance of concrete and its uses have not. We still use concrete to build infrastructure, but building standards have changed dramatically.
Dubai city landscape. Concrete is predominantly used in residential buildings and infrastructure. Image: Pixabay
Its immense use, from house foundations to roads, means that problems cannot easily be fixed through removal of the old and replacement with the new. Such constraints have seen researchers focus on unique ways to solve the problems that widespread use of concrete can create for industry.
In the UK, four universities have created ‘self-healing’ concrete as part of a collaborative project, known as Resilient Materials 4 Life (RM4L), to produce materials that can repair themselves. Currently, monitoring and fixing building materials costs the UK construction industry £40 billion a year.
Microcapsules are mixed through the cement which then break apart when tiny cracks begin to appear. The group have also tested shape-memory polymers that can close the cracks together closely and prevent further damage. These techniques have shown success in long-term trials and in scaled-up structural elements, said Prof Bob Lark, speaking to Materials World magazine. Lark is lead investigator for RM4L at Cardiff University.
RM4L already has 20 industry partners and there is hope that, in the future, technologies can be transferred to other materials, although it has not yet reached the commercialisation stage.
Lark said: ‘What we have to do now is improve the reliability and reduce the cost of the techniques that we have developed so far, but we also need to find other, more efficient and perhaps more tailored approaches that can ensure we address the full range of damage scenarios that structures can experience.’
Making concrete eco-friendly
The abundance of concrete globally comes with an equally large carbon footprint, with concrete production equating to 5% of the annual CO2 produced by humans. For every tonne of concrete made, we contribute one tonne of CO2 to our surroundings. It is primarily due to the vast quantity produced each year that leads to this high level of environmental damage, as concrete is otherwise a ‘low impact’ material.
This inherent characteristic has led some scientists to develop stronger types of concrete. Here, the building features and low environmental impact of the material remain the same, but because less is needed of the stronger concrete to perform the same job, carbon emissions are reduced significantly.
Another method aimed at tackling emissions is the ‘upcycling’ of concrete. At UCLA, researchers have created a closed-loop process by using carbon capture from power plants that would be used to create a 3D-printed CO2NCRETE.
‘It could be a game-changer for climate policy,’ said Prof JR DeShazo, Director at the Luskin Centre for innovation, UCLA. ‘It takes what was a problem and turns it into a benefit in products and services that are going to be very much needed and valued in places like India and China.’