College
College of Science and Engineering
Publish Date
10 May 2019
Related Study Areas
The war on waste glass
Finding new ways of recycling and reusing products in everyday life can be exhausting.
However, glass is a product that requires little effort to reuse. Discovered more than 5000 years ago, glass is 100 per cent recyclable, and being a sustainable product, it retains its quality and has a number of multi-purpose uses. But what happens to glass waste? Due to high costs of transportation and recycling, a significant portion of glass, whether it’s broken or not, goes straight to landfill.
Finding new ways to recycle material that would otherwise contribute to landfill is becoming increasingly important. While glass as a complete product is extremely useful, waste glass is challenging to recycle. Due to various contaminants such as soil, metal or paper, and, in the Tropics, a lack of local recycling plants coupled with high transportation costs, waste glass is another environmental burden. Waste glass joins the list of non-biodegradable materials that take a long time to break down naturally.
One would think that an easy solution to this problem would be not to break any glass — ever. With glass consumption in Australia increasing at an annual average rate of 6.7 per cent since 2011, this solution may not be the most viable. Cairns Regional Council collects around 5000 tonnes of glass waste annually with about 45-50 per cent of this glass recovered and recycled into different forms. The remaining glass, generally in the form of fine glass particles — around 2,600 tonnes per year, cannot be recycled and is destined for landfill.
The Council is searching for sustainable options to recycle this large amount of glass fines, and PhD student Nafisa Tamanna, under the supervision of Dr Rabin Taladhar, senior lecturer at JCU, is intent on providing a solution.
Nafisa’s love of civil engineering and desire for creating a more sustainable product drives her research project.
“I have had a strong interest in reusable or recyclable materials since my undergraduate studies in civil engineering. My interest further developed during my Master’s degree in which I have studied the feasibility of using recycled glass waste as a partial cement replacement in concrete,” she says.
“I chose to complete my doctorate with JCU as I was looking for academics who could help me find out more about working with glass as a recyclable material,” she says. “Dr Tuladhar has great links with the community, both locally and internationally, which means I am able to collaborate with Cairns Regional Council and Pioneer North Queensland – a local concrete manufacturer. Collaboration with the Council and local concrete company ensures that the research is translational and the sustainable concrete we develop through this research will be implemented in the field.”
Nafisa’s PhD project continues the work she started during her master’s degree, analysing the viability of using waste glass in concrete, partially replacing the use of sand and cement.
“We already know that this is possible. The challenge is to determine the exact ratio of waste glass needed to replace the use of cement and sand,” says Nafisa.
Why is using glass in concrete a big deal?
Concrete is the second most used material by humankind — second only to water.
Annually, Australia alone uses approximately 25 million cubic meters of concrete. That’s around 10,000 Olympic-sized swimming pools per year.
Concrete, however, has its own environmental challenges. Mixing stone, sand, cement and water is the traditional recipe for producing concrete. Production of cement is a highly energy intensive process accounting for 5 per cent of the total CO2 emissions from human activities — one tonne of cement releases one tonne of CO2 into the atmosphere.
With a ratio of 1:1 for cement manufacturing and the significant depletion of sand as a natural resource, the need for action is now.
Nafisa’s research is vital for the development of a sustainable concrete mix. Using the links with the local community and Dr Tuladhar’s international connections, Nafisa aims to present a solution to produce sustainable concrete intended for use in light-weight concrete works such as footpaths, and precast concrete elements like drainage pits, kerbs and culverts.
“Being able to recycle a proportion of glass waste into concrete as sand or cement replacement provides a whole new opportunity for recycling glass waste and reduces the amount of waste going to landfill,” Nafisa says. “Furthermore, use of recycled glass in concrete contributes towards sustainable development by reducing the consumption of natural sand and cement.”
“[Recycling] a proportion of glass waste into concrete as sand or cement replacement provides a whole new opportunity for recycling glass waste and reduces the amount of waste going to landfill.”
JCU PhD candidate Nafisa Tamanna