Large-scale industrial mining of asbestos began towards the end of the 19th Century; predominantly in Russia, China, Kazakhstan, and Brazil.
This relatively cheap material with excellent fire and heat resistance, good electrical insulating properties, and high-tensile strength was used widely in the construction industry and in many other products, including brake pads, hair dryers, and industrial filters for wine, beer and pharmaceuticals. Worldwide, an estimated two million tons of asbestos is used annually.
But asbestos exposure can be deadly. Anyone who handles the material or breathes in its fibres puts themselves at risk of lung diseases, such as asbestosis or cancer. The World Health Organization estimates that in a single year over 100,000 deaths are due to asbestos-related diseases.
Lung asbestos bodies after chemical digestion of lung tissue. Image: Wikimedia Commons
‘The truth is that it is a nasty, hazardous, toxic, carcinogenic material that has made millions and millions of people sick,’ says Arthur Frank, Professor of Environmental and Occupational Health at Drexel University, Philadelphia, US. Frank is a longtime advocate for banning the mineral.
To date, around 60 countries have banned the use of asbestos, including the UK. Russia, India, and China, however, still use asbestos in a range of products. The US is the last among developed countries not to ban asbestos entirely. More significant for Western countries are the millions of tonnes of asbestos left in buildings – asbestos becomes a problem if disturbed, especially if the fibres go undetected.
Asbestos is a health risk to construction workers. Image: Pixabay
Traditionally, those who work in the building trade are most at risk, though workers can bring home fibres on their clothes, which poses a risk to anyone they come into contact with.
‘There is a significant amount of data that points to as little as one day of exposure being sufficient to give rise to malignancy in humans and animals,’ says Frank. It’s unclear precisely the cellular mechanism, he says, but health experts agree that asbestos poses a severe public health risk. In the UK, asbestos is responsible for half of work-related cancer deaths.
The European Parliament was one of the first to ban all future asbestos use. Image: European Parliament@Flickr
The European Parliament has pushed for the removal of asbestos from all public buildings by 2028. The asbestos industry, however, argues that it is wrong to say that any exposure to asbestos can kill and believes there is a permissible level of exposure.
In the US, asbestos-related litigation is increasingly common. ‘The companies put up a fight in most cases, delaying settlement until practically the eve of trial and disputing everything they can as to medical diagnosis and causation, and evidence of the plaintiffs’ exposure histories,’ says Barry Castleman, an environmental consultant who has spent 40 years working on asbestos as a public health problem.
However, man-made substitutes for asbestos-based construction materials are available. For over 50 years, asbestos was combined with cement in Europe because its fibres are mechanically strong and durable, says Eshmaeil Ganjian, Professor of Civil Engineering Materials at Coventry University, UK.
PVA is also widely used in glue. Image: Pixabay
These boards were used for internal and external walls as well as for roofs. Europe now uses polyvinyl alcohol – widely known as PVA - in its cement boards, Ganjian says, but this is more expensive than asbestos, which has come down in price over the past 20 years.
Waste not, want not
Ganjian is currently working on a project aimed at replacing asbestos in cement boards in Iran with waste plant fibres, such as Kraft pulp, and polymeric fibres such as acrylic and polypropylene fibres. ‘The idea is to use locally available fibres, so we use cheap acrylic fibres available from petrochemical companies in the region. The strength of cellulose fibres is lower than asbestos fibres, but when we add polypropylene or acrylic or other synthetic fibres then this increases the mechanical strength,’ he explains.
Shiraz, Iran. Image: Wikimedia Commons
The Iranian government subsequently stopped importing asbestos from Russia and banned its use in cement board factories, switching to local alternatives. ‘This was a win-win situation. It saves lives and uses a waste material,’ says Ganjian.
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.’