Could clay be the solution for flammable cladding? Friday, 14 July 2017

Australian engineers have found that treating building cladding with nano-sized particles of clay can prevent cladding fires from spreading, while significantly reducing the heat and smoke from burning.

“During a fire, as the cladding heats up, these small particles of clay react and form an insulation barrier over the polymer plastic, protecting it from the heat and flame,” said Dr Kate Nguyen, leader of the University of Melbourne’s Innovative Fire Engineering research group. “It effectively creates a “ceramic-like” barrier.”

The research comes in the wake of London's Grenfell Tower fire, where it is believed that plastic-backed aluminium cladding contributed to the speed with which the fire engulfed the building.

Following the Grenfell fire, the Victorian state government appointed a taskforce to fast-track its investigation into flammable cladding that followed the 2014 fire at the Lacrosse Building in Melbourne that was similarly covered in aluminium-backed cladding.

Nguyen’s research on nanoclay as a flame retardant goes back to 2011 when she was working with a façade company to improve the fire safety of Glass Fibre Reinforced Polymer (GFRP) cladding. She says the new material developed in this project could be used to manufacture cladding which is both safe and more attractive to builders and architects because it is more flexible than metal-backed cladding and can be used in more varied designs.

The particles of nanoclay are just 5 nm thick. Laboratory test results found that glass-fibre cladding material with the nanoclay particles reduced heat and smoke emissions by 40 per cent, and prevented the fire from spreading. It is believed to be the first time that nanoclay has been used to improve the fire performance of cladding.

The research involved extensive testing of different nanoclays to find clay that would combine properly with the resin.

“Like oil and water, some of the clays just didn’t mix well with resin,” said Nguyen. They eventually settled on a clay called organoclay that is compatible with the organic resin.

“It will still burn, but it won’t produce the same heat and any fire won’t spread,” she said. While there are non-combustible mineral cladding alternatives on the market, she says these are heavier and less architecturally flexible.

Subject to further large scale testing, Nguyen says the nanoclay-treated cladding should be considered as an effective way to retrofit the external cladding of buildings covered with metal-backed plastic cladding.

[London's Grenfell Tower fire. Photo: Natalie Oxford/Twitter]