Extracting sustainable construction materials from mining waste
Concrete has a lot going for it. It’s strong, very forgiving, and it lasts hundreds of years. It’s easy to make, and it’s cheap. But it requires a lot of natural resources which are not unlimited, and this is one of the reasons Associate Professor Priyadharshini Perumal of the University of Oulu is set on finding sustainable construction materials from waste residues. “It’s not that we have to abandon concrete altogether. It’s that we have to find better ways to make it,” Perumal says.
Perumal is a researcher in the Fibre and Particle Engineering research unit at the University of Oulu. She joined the unit as a postdoctoral researcher in 2018 after securing a Marie Curie Fellowship. Currently, she runs a group with 12 researchers with the aim of finding real-world solutions to create sustainable materials.
“I am excited to do basic research, but it should always result in actual solutions that can be applied to real life. Therefore, most of our projects are collaborations with industry. We carry out a lot of pilots to that end,” Perumal explains.
Perumal’s group is focusing on mining and urban mining residues. There is a strong mining industry in Finland and their processes result in a lot of sidestreams and residues. They find small amounts of interesting or profitable elements, like precious metals, and the rest is waste. But the waste is not really waste, Perumal says, because it could be potential raw material for other industries, a resource. So Perumal and her group look at things that produce high volumes of sidestreams and try to add value to such materials to be an alternative raw material, especially for construction.
“We look at a given high volume residue and try to understand its nature, its chemistry and composition and then try to identify the best application for it. There are materials that can be used to replace natural resources like sand or limestone in construction. Or, there are materials we can use as alternatives for cement to avoid the traditional high energy intensive cement process and associated carbon emissions,” Perumal says.
An area for innovation is finding ways to tackle carbon emissions with secondary materials. Making cement creates 8 percent of the world’s CO2 emissions, and low carbon, or zero carbon processes can bring down that percentage.
“So, in the ‘T-capsules’ project we are working with calcium silicate rich wollastonite minerals, waste from the mining industry. By nature, this material is capable of absorbing carbon dioxide. Porous granules made of such a mineral could be used in different industries to capture CO2 from flue gases. These granules could at the end of their life cycle be used as stone replacement in concrete,” Perumal explains.
For every process, Perumal and her group create a complete life cycle analysis. For example, they observe the durability of a given material and map out the end-of-life criteria for it. In some cases a material will be used indoors, and so it is important to look at how it will impact things like thermal comfort, air quality and the aesthetics; basically, how people will feel having that material in their house.
A desire to work with physical materials
Back in her home country, India, Perumal was always interested in arts and crafts and says that she can still create a decent painting. She was intrigued by architecture and thought that studying civil engineering would also teach her architecture. She graduated with a Bachelor’s degree in civil engineering, and then ended up with a software company.
This experience made her realise that she is not a “desk person”, but someone who likes to work with tangible things, materials that she can observe and feel physically and not just study in a virtual environment. She continued her studies and got her Master’s degree in structural and geotechnical engineering before getting her doctorate in construction materials.
“During my PhD my supervisor said I should explore out of India and so I started to look for opportunities outside. In my doctoral thesis work I did a bit on geopolymers, and my current unit in Oulu is one of the best research units in the world for geopolymers. So, this attracted me to Oulu and when they had an open position, I applied for it and got it,” Perumal recounts.
Initially, Perumal’s stint in Oulu was supposed to last for one year, but she kept getting funding. While there was never a plan to continue here, she says Finland has treated her well and there is no reason she shouldn’t continue her work in the country. Her group is an international collection of researchers and there are people from Bangladesh, Finland, Ghana, Iran, Vietnam, Turkey, Nigeria, Italy and India.
“The number of nationalities means we have great food when we organise potlucks together,” Perumal says with a laugh.
“On the other hand, I feel grateful for the opportunity to potentially serve as a positive example for international students in Oulu. While I am deeply motivated by the purpose of my research and the excellent facilities that support my work, I also find it meaningful to demonstrate how someone from abroad can build a career and continue to grow in Finland. Moreover, I recognise the importance of having such role models, particularly for women in the raw materials sector, to inspire and encourage future professionals,”Perumal says.
Plenty of opportunities in Oulu
Perumal has been in Oulu for seven years and enjoys the area. She says the first time she saw the aurora she got goosebumps, and her favorite place is Koiteli, the rapids some 30 kilometers outside of Oulu. Her research is going strong and she has three EU projects as well as secured funding for her group until 2027. She says there are enough resources to continue her research as well as many opportunities to write new proposals. In addition to working with the mining industry, her group is working with municipal waste management to upcycle urban mining sidestreams like household waste and excavation waste from tunnels and other infrastructure projects.
The needs of infrastructure are only growing in the world as there are more and more people in need of housing. This results in depleting natural resources which is what Perumal is trying to tackle in her work. She says that this is a very good time for research like hers.
“There is a lot of push from governments and policy makers for any industry that creates a lot of waste to also take care of it. I see the change in people’s mentality in the business, they also care about these issues. We don’t have to convince anyone that we need to act to preserve nature, it is plain to see. As a result, we have people coming to us and saying we have all this waste, do you have a solution? And that’s what we are trying to provide,” Perumal says.
Priyadharshini Perumal's researcher profile
The list of the Kvantum Institute's Emerging projects 2023-2026
Story and Photos: Janne-Pekka Manninen