A low carbon cement that lowers carbon dioxide emissions by 10 per cent has become the leading choice for the bulk of new concrete construction projects in British Columbia.
The Contempra brand, made using Portland limestone cement (PLC), has now reached 50 per cent of the market share in B.C., according to the Cement Association of Canada (CAC). Since its launch two years ago in Canada, more than 23,000 tons of greenhouse gases have been taken out of the atmosphere each year—comparable to saving 9.7 million litres of gasoline.
So, what’s the difference between traditional cement and Contempra?
Michael McSweeney, president and CEO of the CAC, explains that instead of processing limestone through the kiln as you normally would, 15 per cent ground limestone is added to the clinker at the end of the process. And by not processing 100 per cent of the mix in the cement kiln, the amount of coal needed to fuel it is decreased, which in turn significantly reduces the amount of energy used.
“When the limestone goes in the kiln it is heated up to 1,450 degrees C and you’re causing a chemical reaction turning the limestone almost into a molten lava. Then it cools very quickly and is turned into almost a metal
substance, which is then ground into clinker,” he says. “By adding 15 per cent limestone at the end of the process,
you have a net savings of 10 per cent greenhouse gas in the cement that you’ve just produced.”
So far, Contempra has seen its best results in B.C., where in addition to several condominium, commercial and institutional projects, other Contempra projects already completed or ongoing include the Arthur Erickson Building, the Wall Center False Creek Development and ONNI’s Evelyn master-planned community. “We’re hoping to get Contempra somewhere between 80-90 per cent market share across Canada within five years (by 2016),” says McSweeney. “In B.C. we’re well on our way.”
But PLC is nothing new. It’s been used in Europe for more than 25 years. It just took a while to make its way through Canada’s codes and standards process, which in a way is good according to McSweeney, because of our different climate conditions. Contempra was included in the 2010 national building code, and has since been added to the British Columbia, Ontario and Quebec building codes.
A number of Canadian multinational companies have been using PLC with partners in Europe for years and were pushing for it at home to reduce carbon dioxide emissions in the cement manufacturing process. Lafarge manufactures and ships Contempra from its Bath, Ont., Richmond, B.C. and St. Constant, Que. cement plants. Daniel Heroux, brownfield segment manager for Lafarge, said it fits perfectly with their overall strategy of “building better cities,” and sustainable construction is something that’s always important.
Lafarge was one of the first Canadian companies to be involved in studies to show PLC is just as reliable as traditional cement. In 2008 Lafarge partnered with the University of Toronto and the University of New Brunswick in a project that compared PLC and traditional cement side by side. Since then lots of major projects in Canada have used it, such as a 16-storey federal government building in Gatineau, but at the same time it’s not just one or two off.
“It is being used across the spectrum,” he says, adding two hospitals going up in the Montreal area are using it exclusively. Heroux says a key turning point took place when Contempra was added to the national and three provincial building codes. Since then it has become the new standard.
For McSweeney, he hopes the initial success of Contempra for use in buildings will carry over to roads and pavements as well. In Ontario, it is currently being tested to see how it holds up over the winter. In some places this will be the second or third winter season. “They want to see how it reacts to salt, for example,” he said.
McSweeney said the surface of concrete pavement is typically 10 degrees C cooler than asphalt and contributes less to the “heat island effect.” And since concrete is a rigid surface, buses, trucks and other heavy vehicles ride on top of it as opposed to into it as they do for asphalt. “You can save between three to seven per cent in fuel because you’re riding on top of the pavement,” he said.
He added that overall, most people don’t normally see the cement industry as innovative, but he hopes that stereotype might begin to change thanks to products like Contempra. “We are doing what we can to become part of the solution as opposed to being part of the problem,” he said.
