From waste material to new material: UTS researchers create novel ceramic

When researchers in the UTS Material Ecologies Design Lab (MEDL) started playing around with recycled glass, they weren’t expecting to create a novel material — but that’s exactly what they did. 

That material, which is made of particles known as glass ‘fines’ mixed with a bio-based binder, is essentially a new type of ceramic that can be used to make tiles, bathroom fixtures, bricks and more. 

It offers exciting potential to transform more than just MEDL’s academic fortunes — in future, it could drive a new generation of low-embodied-carbon building products that would enhance the sustainability of Australia’s built environment. 

A sustainable glass solution 

The research project came about almost by accident. At the time, Dr Stefan Lie, Ella Williams and Nahum McLean from the School of Design and Professor Tim Schork* from the School of Architecture were experimenting with diatoms, the microscopic algae skeletons made of pure silica, as the starting point for a new material. 

“And then I thought well, if we can do this with [diatoms], why can’t we do it with recycled glass?” says Dr Lie, an acclaimed product designer and one of the co-founders of MEDL.

The team shifted their focus to the use of glass fines, which are tiny particles left over from the recycling process. While they can be used to make sand for in road construction, they’re essentially a waste product — some 189,000 tonnes of glass fines wind up in landfill every year. 

Dr Lie and his colleagues were drawn to the material because of its potential to overcome a pressing waste issue: glass is a highly energy intensive material to make and recycle, largely as a result of the high temperatures required to melt its underlying materials together. 

As such, any glass that winds up in landfill represents a significant waste of embodied energy. 

“Once a glass smelter is running, it’s 24/7, 12 months a year. It’s never turned off [and] they run at [up to] 1300 degrees (Celsius),” Dr Lie says. 

“The energy consumption is a major issue. Making glass sustainable is almost impossible.”

Creating a new ceramic 

The research team started developing a series of bio-based binders that would hold the particles together to create a ceramic. The challenge was to create a binder that could withstand being fired in a kiln while maintaining the integrity of the material. 

“It was all about the binder. We knew that if you heat a pile of glass powder in an oven, it’s going to melt into a blob,” Dr Lie says. 

“The problem we needed to [figure] out was, with the various binders we were experimenting with, if it gets to 300, 400, 500 degrees, when does the binder burn off and the whole thing collapse?”

Once they’d perfected their binder recipe, the details of which remain a tightly guarded secret, they started mixing the binder, glass particles and water together to create a glass paste. They used the paste to create a series of small cups and then fired them to figure out the temperature at which the material became waterproof. 

The results were compelling: the material, which acts like a ceramic, becomes waterproof at just 740 degrees Celsius, representing significantly lower energy inputs than those required in the smeltering process. Equally exciting is the fact that products made from this material can be ground down into a powder, re-mixed with fresh binding agent and used again and again. 

Glass is not like plastic. It’s almost infinitely recyclable; it hardly degrades
– Dr Lie

To date, the researchers have produced a series of wall and floor tiles that have been independently tested to ensure they meet key performance requirements stipulated by the Building Code of Australia for use in kitchens and bathrooms. The work has recently been registered as a provisional patent.

The next step will be to find industry partners interested in licensing the patent as well as expanding the product range, with the ultimate aim of marketing the products among architects and developers in Australia and beyond.

MEDL is a design-led research centre at UTS with a focus on material cultures, thinking and futures that support the transition towards more regenerative systems.

*Tim Schork is now a Professor at the School of Architecture and Built Environment, Faculty of Engineering, Queensland University of Technology, as well as an Adjunct Professor at the University of Technology Sydney.