Cement is made by heating limestone with clay at high temperatures, and is responsible for 5 percent of the global carbon dioxide emissions, with a ton of CO2 released for every ton of cement produced. To reduce that figure, a team of researchers from the University of Dundee in UK, developed an environmentally-friendly cement made of waste organic materials, such as rice husks.
The researchers are looking into ways of reducing this carbon footprint by replacing part of the Portland cement with waste materials such as fly ash from burning coal, slag from iron works and even rice husks.
Dr Kevin Paine, from the University of Bath’s Department of Architecture & Civil Engineering, and Dr Moray Newlands and Professor Ravinder Dhir, from the Concrete Technology Unit at Dundee have recently returned from a UKIERI meeting in Punjab, India, where they presented their latest research and shared ideas with colleagues to develop new types of cement with a lower carbon footprint.
Dr Paine explained: “Concrete is the second most used material in the world after water, and so reducing the CO2 emissions produced by it could make a real difference to climate change.
“India’s infrastructure is developing rapidly and it is the second largest producer of cement in the world, after China. Therefore this collaboration with Indian research institutes is developing the new technologies in the countries where i’s most needed.
“There’s no single perfect replacement for Portland cement – instead we are looking into a number of ‘green’ cements that use different waste materials depending on what is locally available. For example, in India you might burn rice husks to make silica to mix with the cement; in the UK you might use fly ash made from burning coal.”
Dr Newlands added: “The scale of the problem facing infrastructure development in India and the UK means that collaboration between a number of institutions is the only way to reach our goals. We have to look at the environmental challenges collectively to make a meaningful impact.”
Building green doesn’t always mean you have to preserve the inside temperature at all costs – you have to take into account all the adjacent processes involved in building and their particular carbon footprint. Such an example is polystyrene, that can yield fabulous energetic gains, but which on the other side is anything but green.