SCIENTISTS have found that a new method of colouring concrete using waste printer toner is waterproof and resistant to ultraviolet light – which means it can keep its hue over a longer period.

A team from the University of Dundee, along with Moock Environmental Solutions and Inverurie Precast, revealed the method of recycling toner from old printing cartridges earlier this year, but further tests have now shown its added resilience when used to colour concrete.

The team mixed cyan, yellow, magenta and black recovered toner powder (RTP), and found it was possible to produce a range of colours in concrete and cement without affecting the integrity of the finished substance.

There are coloured concretes already on the market, but their range is limited by production methods and the excessive cost of producing more distinctive colours, such as blue, which requires the use of cobalt. The Dundee team, led by Dr Moray Newlands from the university’s School of Science and Engineering, said it believed mass production using RTP would cost significantly less and allow a far greater range of tints to be manufactured.

In a collaborative project funded by the Construction Scotland Innovation Centre (CSIC), they discovered that introducing RTP into the concrete structure at the beginning of the construction cycle also offered good waterproofing.

The industry’s current standard and state-of-the-art processes for waterproofing concrete use either vapour-retarding membranes or pore blockers.

READ MORE: Recovered toner powder helps transform landmarks

Similar measures are needed to protect against ingress and damage by chloride from de-icing salt in winter and the addition of the RTP would remove the need for these processes, at no extra cost.

This has the added benefit of making it a financially attractive alternative product in the precast concrete market, a material that is common in the walls of the Cidade das Artes in Rio de Janeiro, Kengo Kuma’s V&A Dundee, and the three sails of the Richard Meier-designed Jubilee Church, near Rome.

The new development bodes well for the future for similar and potentially brighter structures.

“Around 10% of toner remains in a cartridge at the end of its life, so we’ve been looking at ways in which we can utilise it and prevent it being sent to landfill,” said Newlands.

“Toner powder is incredibly fine, but cannot be recycled into new cartridges as it goes through thermal cycles and changes size once it is involved in the printing process.”

Newlands added: “Inverurie Precast is producing samples which we are testing to see how they resist water and how strong they are.

“As engineers, the main thing we’re concerned with is ensuring that the properties of the concrete remain similar or are improved by adding colour to it. If that is the case then architects will be able to use it as they wish.”

Jennifer Smart, business relationship manager at CSIC, said: “This project is just one of many that demonstrates how industry and

academia is working together to drive innovation, and CSIC is delighted to be supporting this exciting development.

“The product offers not only an environmental solution to a potential waste problem, but has the potential to reduce ongoing structure maintenance costs due to its waterproofing benefit, in addition to using colour in creative and interesting ways.”