Greener cement from rice husks?

Every time a tonne of cement is manufactured, it produces about a tonne of carbon dioxide. Now, a  revolutionary new concrete made from rice husk and coal ash waste is being developed in a plan to tackle climate change.

Portland cement, a main constituent of concrete, is made by heating limestone with clay at high temperatures. 

Apart from concrete, cement is a basic ingredient of mortar, stucco and most non-specialty grout. “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,” said Kevin Paine, a member of  the UK-India research team.

The UK researchers - from the Universities of Dundee (Scotland) and Bath (southern England) - are looking into ways of reducing cement’s 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.

Moray Newlands and Professor Ravindra Dhir from the Concrete Technology Unit at Dundee University, and Kevin Paine from Bath University's Department of Architecture and Civil Engineering, recently returned from a UKIERI meeting in Punjab. At the meeting,  they presented their latest research and shared  ideas with colleagues to develop new types of cement that would be more ecologically sound.

Paine said, “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 it is most needed.”

He continued, “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.”

Newlands, from Dundee University’s Concrete Technology Unit, said, “The scale of the problem facing infrastructure development in India and the UK mans that collaboration between a number of institutions is the only way to reach our goals. We have to look at the environmental changes collectively to make a meaningful impact.”

The Dundee Concrete Technology Unit conducts fundamental and applied multidisciplinary research to assist the concrete construction industry in becoming more innovative, competitive and environmentally sustainable. 

Paine continues to collaborate with colleagues at Dundee, testing the durability of concrete made with different cements under a range of environmental conditions. Newlands’ research is concerned with using waste materials such as alternative cements in concrete and establishing long-term durability of infrastructure.