Concrete innovation: a deep dive into the long-term impacts of cement

Link to original Publication: https://www.canadiancontractor.ca/features/concrete-innovation-a-deep-dive-into-the-long-term-impacts-of-cement/

Concrete has been the most relied upon and used building material not only in Canada but the entire world. In fact, concrete is the second most consumed material in the world next to water, according to research provided by the Massachusetts Institute of Technology. Concrete provides structural benefits due to its reliability and durability. Concrete does not rust, absorbs and retains heat and is water- and wind-resistant. It is also highly accessible, which makes it cost-effective and affordable, especially if you are building on a budget. However, the cement industry is responsible for eight per cent of global greenhouse gases and Canada produces approximately 60 million tonnes of concrete each year, explains the Canada Green Building Council (CAGBC). 

The production process of creating concrete releases CO2. explains Kevin Yuers, vice president of product development at Kryton International. “Concrete is made up of rock, sand and cement,” he says. “And cement is the glue that keeps everything together, but it’s what causes GHG.” Modern methods have been put in place to reduce GHG emissions from cement, explains Yuers. “One ton of cement used to produce one ton of CO2,” he says. “But, now they’ve gotten it down to produce half a ton.” According to the CAGBC, a way to reduce embodied carbon in concrete is to add supplementary cementitious materials (SCM) to concrete mixes, reducing the amount of cement. SCM use is common in Canada, typically 10 to 16 percent of concrete mixes, explains the CAGBC in its white paper. In other provinces, up to 40 per cent of SCM is used in mixes. 

“Any time you can reduce a small amount of cement, you can reduce an equal amount of GHG.” Due to concrete being naturally porous, this process can be difficult as there needs to be a sort of glue, that keeps the mixture together – which in most cases would be cement or SCM. Companies like Lafarge Canada and Kryton have created more sustainable concrete products for the Canadian market. 

Yuers offers a perspective on how Kryton creates its Smart Concrete products with Krystol Internal Membrane (KIM). KIM is a hydrophilic crystalline admixture used to create permanently waterproof concrete and keep it durable. “It fills the pores and capillaries of concrete with crystals,” explains Yuers. KIM does not replace cement, however, 20 percent of Kryton’s repair products are Smart Concrete. 

The only downside of using alternatives is that they are often twice the amount of cement and only sometimes as effective. “That’s the rub,” says Yuers. “This is a major challenge the industry faces.” Hard-Cem, is an integral admixture that doubles concrete wear to remain durable over time. Hard-Cem does not typically replace cement. However, it does offer an opportunity to reduce cement and CO2. If a contractor is looking to increase the abrasion resistance of their concrete floor, they may consider two options, explains Yuers. One is to increase the strength of the concrete by adding more cement. The other is to add Hard-Cem, which will increase abrasion resistance without adding cement. “Adding Hard-Cem will result in the concrete mix with 25 percent less cement.”

Kryton KIM tossed into the mixer. Image courtesy of Kryton.

Timber is also a common substitute for concrete entirely and in the last decade, there has been a push across the nation to build with mass timber. A benefit to timber, according to the CAGBC is more predictable construction times and lower embodied-carbon production. However, timber can only go so far, as it is considered for builds less than 12 storeys. 

There is no clear-cut solution to the cement dilemma – although there are options a developer, contractor or renovator can choose from. Yuers encourages those in the industry to use more sustainable concrete solutions like KIM, despite the cost. “We need to embrace newer technologies in construction,” he says. “Ultimately, these products will save you money in the long run and certainly without adding CO2 to the environment.”