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Building with a more durable, greener concrete Add to ...

A Canadian company is building a case for a greener, stronger concrete but is fighting resistance in the construction industry.

"The cement and the concrete industry is enormous worldwide. ... And they do things a certain way and they have done those things that way for years and years and years," says Barry Lester, chairman of Whitemud Resources Inc., which mines kaolin, a white-coloured clay, in southern Saskatchewan and turns it into metakaolin, which is used as a supplement to cement.

"To get people to consider making a change we are trying to turn the freighter, and it takes a long time to turn it," Mr. Lester says.

Between 90 million and 140 million tonnes of cement are produced each year in North America. Much of it is mixed into concrete that is then poured into commercial real estate projects where owners, tenants and building firms are becoming increasingly concerned with environmental standards.

As the industry debates green values and sustainability, Whitemud has spotted its opportunity to make a difference.

Whitemud says metakaolin is more durable than regular Portland cement, or any of the other widely used supplementary cement materials, and it is bringing it to market cheaper than previous suppliers.

It reduces greenhouse-gas emissions, saves time and money on the construction site and will make buildings and other construction projects last 100 years instead of 50 or 60, says Whitemud, which is based in Calgary.

"The only downside to metakaolin is inertia in the industry," adds Mr. Lester, who helped to lead the engineering team for the Confederation Bridge, which links Prince Edward Island to the mainland.

"They have enormous environmental problems right now in the cement industry and we can help them with those problems," he says.

The cement industry, however, has been working on becoming more green. In its 2008 sustainability report, the Cement Association of Canada says that, between 1990 and 2006, the industry improved its energy efficiency by 11 per cent and reduced the greenhouse-gas emission rate of production by 6.4 per cent.

Supplementary cementing materials (SCMs) are currently mixed with cement and reduce the carbon footprint of the finished product because they create fewer emissions than cement. Among the substances commonly used are fly ash, slag and silica fume.

Whitemud, with its kaolin mine at Wood Mountain, about 170 kilometres southwest of Regina, has 160 million tonnes of kaolin ore. It plans initially to make 200,000 tonnes of metakaolin per year.

Metakaolin is an accepted SCM and has been used for decades, with the only supply in North America traditionally coming from manufacturers in Georgia and South Carolina. Those manufacturers supply the cement industry only as a sideline. Their primary market is making metakaolin - a fine, white powder - as a coating for glossy paper.

Whitemud, which was formed in 2005, has focused on how to make its product cheaper for the cement industry, while the manufacturers in the United States use a more intensive process to make the paper-grade metakaolin.

"Their process is much more intensive. Typically it is a wet process and uses a lot of chemicals to bleach the clay. They use big magnets to pull iron out of it and, because it is a wet process, they have to remove that water, and are using a lot of energy to drive off that water," says Kelly Babichuk, president and chief operating officer of Whitemud. "Our process is dry. We don't use one ounce of water in the process."

With its new manufacturing methods, Whitemud's metakaolin will cost about one-third of the U.S. version, which sells for $600 to $700 a tonne.

On the green part of the equation, Whitemud says its process generates 55 per cent fewer greenhouse-gas emissions than cement - largely because kaolin requires heating to 800 degrees Celsius to be used in concrete while cement requires heating to 2,000 degrees Celsius. Metakaolin can be used to replace 10 to 20 per cent of the cement needed to make concrete.

"I kind of think about metakaolin as being like a multi-vitamin for concrete because there are so many issues with concrete that metakaolin can address," Mr. Lester says. He adds that that metakaolin-enriched concrete reaches the strength where it can be worked on more quickly and, depending on the aggregate used, it can also make the concrete look more white.

Craig Dummer, senior superintendent with the construction and engineering company EllisDon, is one of those already sold on its benefits. His crews were able to work on the concrete more quickly at the five-storey, 250,000-square-foot Energy Environment Experiential Learning Building under construction at the University of Calgary. If he had used regular Portland cement or cement with fly ash, it would have taken up to a week for the concrete to set up. With metakaolin, it took three days.

"That means the equipment that I have got tied up here for form work is being rotated faster," he says. "Therefore there are savings involved. Usually when you talk LEED, you are talking an added cost ... but this is win-win."

As an SCM, metakaolin earns points toward getting Leadership in Energy and Environmental Design certification. LEED also encourages the use of materials processed within 2,400 kilometres of construction sites if delivered by rail and 800 kilometres if the material is trucked to the site. With its location is southern Saskatchewan and its rail link, Whitemud can reach most of Canada, the United States and even into Mexico and still fall within LEED guidelines, says Calgary architect Louis Aussant, a member of the Canada Green Building Council.

While Whitemud has found a market for its product in Canada and the United States, including EnCana's two-million-square-foot Bow Tower under construction in Calgary, it still struggles to get wider acceptance.

Michel De Spot, CEO of the EcoSmart Foundation, a Vancouver-based non-profit corporation that promotes sustainable practices in the construction industry, says he prefers the use of recycled SCMs to metakaolin. Fly ash, slag and silica fume are all waste products of other industrial processes, while kaolin has to be mined and then transformed into metakaolin. "We would prefer, by far, anything which is recycled," he says.

The bottom line is economics, says Robert Day, of the Schulich School of Engineering. Prof. Day pegs the cost of cement at about $220 per tonne, fly ash at about $110 and silica fume at about $800. "I think they are selling it [Whitemud's metakaolin]at around the same price as cement. With a more unknown product than cement, and with a very conservative civil engineering or engineering field, they tend to stick with what they know works."

But Mr. Aussant says using Whitemud's metakaolin "is a no-brainer."

"We live in a disposable society and the thing that we, as architects and green thinkers, have to do is encourage things that are a lot more durable and less disposable. We should be designing and building buildings for 100 to 200 years."


By the numbers

1 tonne

Amount of CO2 produced by the manufacture of one tonne of cement. The CO2 is created by fuel combustion and the calcination of raw materials.

7 to 8 per cent

Share of global greenhouse gas emissions produced by cement manufacturing

1.8 per cent

Share of Canadian greenhouse gas emissions produced by cement manufacturing

55 per cent

Percentage fewer greenhouse gases emitted in the production of metakaolin compared with cement.

Sources: Canadian Cement

Industry 2008 Sustainability

Report, Whitemud

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