Fly ash, a source of fireproof concrete?

May 27th, 2009 - 1:39 pm ICT by IANS  

Sydney, May 27 (IANS) Tens of millions of tonnes of fly ash, produced worldwide annually by coal fired power stations, could become a valuable source for fireproof concretes.
Research by William Rickard and colleagues at the Curtin University of Technology (CUT), Perth, has shown that fly ash-based geopolymers exhibit remarkable fire resistance while maintaining superior mechanical strength.

The team has made geopolymers, a cement-like material formed by dissolving materials that contain silicon and aluminium, such as fly ash, in a highly alkaline solution for use in high temperature applications such as fireproofing and building insulation.

Rickard, who has been concentrating on high temperature applications of fly ash geopolymers, said he became interested in the field after reading of their engineering and environmental potential. “We have found the geopolymers have great fire resistance.”

“Because of their amorphous polymeric structure, geopolymers maintain structural stability to much higher temperatures than conventional concrete, in which calcium based phases break down above 600 degrees. In geopolymers, strength is maintained or increased up to 1,200 degrees,” Rickard said.

About 46 percent of the fly ash from power stations — worth some 120 million Australian dollars annually — is re-used, with the greatest part employed as filler for cement.

Beyond reducing source material cost and lessening the amount of fly ash being dumped in landfill, making geopolymers produces 80 percent less greenhouse gases than portland cement, the cement used in daily construction.

Cement manufacture contributes five to eight percent of the world’s greenhouse gas emissions, said a CUT release.

Rickard will present these results at the Pathfinders: the Innovators Conference at the National Convention Centre in Canberra May 26-28.

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