Combustion residue lowers carbon dioxide emissions in concrete

The Norwegian concrete industry won worldwide acclaim for its gigantic North Sea constructions. Its best-known achievement was the Troll A platform in 1995 -- the largest structure ever moved by man.

Today the concrete industry is orchestrating new achievements on the environmental front.

"We need to be proactive," says Terje Rønning, R&D Manager at cement producer Norcem and chairman of the board of the Concrete Innovation Centre (COIN). Dr Rønning freely admits that environmentally speaking, concrete often falls short in comparison with other building materials. Thus, COIN intends to become no less than the European leader in research on concrete. The centre has been granted status and funding as one of the 14 Centres for Research-based Innovation under the Research Council.

Turning waste into a resource

Researchers and the industry are attacking the environmental challenge in two ways. One is by substituting CO₂-neutral fuel for the coal and oil used in cement kilns. The other is by replacing some of the limestone (calcium carbonate or CaCO₂), which is the primary raw material in cement production, with other raw materials that do not emit CO₂.

"We have launched a new cement product, specially intended for civil engineering structures, in which 20 per cent of the Portland clinker is replaced by fly ash, a combustion residue generated at coal-fired power plants that does not emit CO₂," explains Knut O. Kjellsen, Chief Engineer at Norcem.

"This residue material is not only more environment-friendly, it also has properties that prevent cracking and protect against penetration by seawater and road salt."