Land down underFly ash as source material for fireproof concrete

Published 28 May 2009

Australia’s coal-fired power plants produce 13.5 million tons of fly ash every year; researchers show that this ash may be used as valuable source material for fireproof concrete;

Here is a useful innovation from a country which punches above its weight when it comes to technological innovation. Australasia’s coal-fired power stations produce 13.5 million ton of fly ash every year. This ash could become a valuable source material for fireproof concretes.

Research by William Rickard and his colleagues at the Cooperative Research Center for Sustainable Resource Processing at Curtin University of Technology in Perth has shown that fly-ash-based geopolymers exhibit remarkable fire resistance while maintaining a high degree of mechanical strength.

The team has made geopolymers, a cement-like material formed by dissolving materials that contain silicon and aluminum, such as fly ash, in a highly alkaline solution for use in high-temperature applications such as fireproofing and building insulation. Rickard said: “Because of their amorphous polymeric structure, geopolymers maintain structural stability to much higher temperatures than conventional concrete.”

About 46 percent of the fly ash from power stations — worth some $120 million annually — is reused, with the greatest part employed as filler for cement. For example, the concrete Seacliff Bridge between Sydney and Wollongong includes 25 percent fly ash from the Eraring power station in the NSW Hunter Valley.

As well as using a waste product from burning coal in power stations and providing a strong construction material designed to insulate against fire, geopolymers also reduce greenhouse gas emissions. Beyond reducing source material cost and lessening the amount of fly ash being dumped in landfill, making geopolymers produces 80 per cent less greenhouse gases than Portland cement. Cement manufacture contributes five to eight per cent of the world’s greenhouse gas emissions.