Abouzar Sadrekarimi doesn’t want you to feel the Earth move beneath your feet, so he is leading work that helps strengthen it.
By adding urea and calcium to the soil, Sadrekarimi and his team at Western Engineering have created a bio-cement that improves the structural integrity of the ground we walk – and build – upon. The novel approach has already proved to have practical applications for mining sites and wet areas susceptible to earthquakes.
In studies published in the Canadian Geotechnical Journal and Soil Dynamics and Earthquake Engineering, Sadrekarimi and his students show for the first time that the technique can be used to stiffen sands around the Fraser River in British Columbia. The bio-cement could help address issues related to earthquakes, slope failures and sinking foundations.
“Earthquakes can lead to liquefication of soils in British Columbia, wreaking havoc on infrastructure like bridges, roads and dams,” said Sadrekarimi, who serves as a director of Western’s Geotechnical Research Centre.
Sadrekarimi hopes the work will help develop better building codes and reduce the cost of structures like foundations and dams, which would no longer need to be dug as deeply into more solid ground. As the method uses inert chemicals and microbes already found in the soil, bio-cemented soil is also a natural way of mitigating risk.
Currently, Sadrekarimi and his team are studying bio-cement to solidify gold mine tailings samples collected from a site in Québec. The team added microbes to the tailings and fed them agar and urea to help them grow, causing them to bind with the tailings and precipitate calcite to make rock. The effort can help strengthen tailings dams to prevent failures, like those that occurred in Brazil in 2015 and 2019.
“Tailings dams need to be designed for large earthquakes as they are permanent structures that can’t be removed because they contain waste and toxic materials,” Sadrekarimi said. “Several have already failed, killing hundreds of people.”
The solution should provide a cost-effective way of managing these risks across the country, including in Ontario, where approximately 4,000 abandoned mine sites have been identified as hazardous to public health and safety.