A nano risk
A report looks into the potential dangers of nanotechnology in the construction industry. Ellis Davies investigates.
Nanomaterials have been enjoying the spotlight in recent years, and have seeped into the construction industry in the form of nano-coatings, nanotube-infused concrete and fire retardant nano-clays. But, does the uptake of these materials pose a threat? Researchers at Loughborough University, UK, have compiled a report indicating any potential risks associated with the use of nanomaterials in the built environment, as well as dispelling some common beliefs.
What the team found is that nanotechnology in construction is not as widespread as some believe.
The report, Nanotechnology in construction and demolition: what we know, what we don’t, therefore seeks to tackle what the researchers refer to as confusion and anxiety about nanotechnology.
Professor of Construction Engineering Management Alistair Gibb, of Loughborough University, told Clay Technology, ‘There is some confusion in society generally as to how nanotechnology could affect people. In construction, most people are not sure what is happening. Greater access to online papers, which cover various aspects of nanotechnology, also heighten the tension,’ he said. ‘We set about finding out what nanotechnology in construction is and where it is, and trying to make sense of the technical publications to determine whether nanotechnology is hazardous or not.’
A particular concern, the use of carbon nanotubes in concrete, is one that they attempted to bust.
Dr Wendy Jones, Research Associate at Loughborough University said, ‘The study was about getting clarity on what is actually being used. If you look at the academic literature, there are thousands of papers about carbon nanotubes in concrete, but in reality, there are very few cases of this being used in the real world. Most of it is in development.’
Asbestos or not?
The use of carbon nanotubes has faced some resistance because of comparisons to asbestos. In November 2017, the Medical Research Council, UK, reported on a study at its Toxicology Unit, which placed long carbon nanotubes or asbestos fibres into the pleural space, which separates the lungs and chest wall of mice, where mesothelioma usually develops in humans. Over a number of months, researchers found that like asbestos fibres, long nanotubes caused long-term inflammation in the pleural space. This led to inactivation and loss of the genes that suppress the formation of tumours.
‘Carbon nanotubes might be like asbestos if they were long and straight,’ Gibb said.
‘In theory, they can be, and there are people trying to do this because they can be used to do lots of exciting things in this form. But, the reality is, as far as we could tell, that all applications already in construction, or that are likely to be used in the near future, do not use this kind of carbon nanotube because they are too expensive to create.’
Rather, the carbon nanotubes are tangled, not very long, and bound together in a way that limits the likelihood of a long, straight piece getting loose, the researchers say.
Put a label on it
Jones added that finding out which companies are using carbon nanotubes, and in what materials, is quite difficult. ‘We have no way of knowing what shape [the nanotubes] are because it is not published, and it is not required to be published – companies aren’t even required to say that there are nanotubes in the concrete [or other materials], but it is often marketed as a selling point. The requirements are, in terms of labelling, very minimal, so it is difficult to get accurate information,’ she said.
This issue has been addressed in some countries, such as France and Belgium, where companies are now required to declare to the governing body that nanomaterials are being used in products. However, at the EU level, this approach has been dismissed.
Gibb suggested that even though materials often aren’t labelled, those in construction, particularly designers, should be asking the question of what they consist of and recording where any nano-infused materials are being used. ‘The rationale for this comes from asbestos – if we knew where it was, it would not have been such a large problem. Its danger was established a number of decades ago, but nobody really knew where it was,’ he said. ‘If the jury is out on nanotechnology at the moment, we can encourage designers to note where it is being used. The industry has tools for doing this, in the form of a health and safety file, which includes a log of potentially dangerous materials – why not put nanomaterial details in there?’
Building information modelling could be used to help record this data. It is used to design most new buildings, and the intelligent 3D computer model is able to store data on the materials used. ‘It is quite feasible that it could be populated with this sort of data, searchable in the future,’ Gibb said.
Read the report at bit.ly/2DciEOy