Green cement

Green cement

Using a by-product of the pulp and paper industry to create a kind of super glue for cement
May 29, 2014

The cement industry’s carbon footprint is massive. From the energy used to extract raw materials to the emissions released throughout the cement manufacturing process, it all adds up to an estimated 6 to 10 percent of the world’s annual greenhouse gas emissions.

Moreover, this is part of a vicious feedback loop. As carbon emissions and temperatures increase, so does the strain on our infrastructure. Higher carbon dioxide levels in the atmosphere lead to increased corrosion of metal supports in concrete structures, and rising global temperatures and extreme weather events add additional thermal stresses, another dimension in this “perfect storm” of infrastructure degradation.

Canadian researchers are working closely with the cement industry to help make it more sustainable. They’re exploring ways to decrease emissions during production and new uses for industrial by-products, such as old tires, in the production of concrete structures, which are typically composed of 10 to 15 percent cement. This minimizes waste in landfills and decreases the amount of material used.

At Lakehead University in Thunder Bay, Ont., researchers are taking things even further. Lionel Catalan, chair of the university’s chemical engineering department, teamed up with chemistry professor Stephen Kinrade to develop a cement additive that can make concrete up to 40 percent stronger and reduce greenhouse gas emissions by using less material, making it both green and cost-effective in the long run. The additive, a type of sugar alcohol called a polyol, is a by-product of the pulp and paper industry and another instance of minimizing waste.

Concrete is a hardened mix of substances that have bonded together to form the solid structures we see all around us. “When concrete fails, it is usually in the bond,” says Catalan. “It’s the glue that holds those materials together.” The cement additive works by making that bond stronger, holding the aggregate mix together more effectively and with less material. The other plus, says Catalan, is that the material is very workable: It doesn’t take too long or too short a time to harden, and it has just the right consistency to allow construction workers to mould it effectively.

The new product is currently licensed to GreenCentre Canada, located at the Innovation Park at Queen’s University, in Kingston, Ont. GreenCentre Canada commercializes green-chemistry innovation and is testing and further developing the additive to prepare it for the market and a wide range of applications in Canada and beyond.