New Noninvasive Technique Measures Steel Rebar Corrosion

Researcher Arthur Situm at the Canadian Light Source synchrotron. Photo by Dave Stobbe for the University of Saskatchewan.

University of Saskatchewan (USask) (Saskatoon, Saskatchewan, Canada) doctoral student Arthur Situm has developed a new noninvasive technique to study the rusting of steel. Situm believes the research could help with the safety of potash mining and the construction of buildings, roads, and bridges.  

At the Canadian Light Source (CLS) synchrotron, a USask national research facility, Situm is studying how the protective coatings of rebars—the steel reinforcing bars used to strengthen concrete—withstand corrosion. He did his research with the potash mining industry in mind, since salt from potash mining can seep through porous concrete and cause rebar to rust faster, which requires more frequent replacements.

“Concrete usually holds up pretty well even when the rebar is somewhat rusted,” Situm says. “But the method I developed helps you determine at which point the protective coatings of the rebars fail, so that researchers can develop better coatings.” Unlike other methods used to study corrosion, Situm’s synchrotron technique, which stems from x-rays, a microscope, and the CLS particle accelerator, shows how effective coatings are without removing them from rebar.

Normally, coating removal damages samples by making them unusable for future testing and may interfere with corrosion of the coating itself. In his work, Situm has simulated different conditions for multiple types of protective coatings in the lab to understand how the materials and surface chemicals can respond. His results show that a fusion-bonded epoxy can withstand corrosion better than other types of coatings tested.

Situm’s technique ‘maps’ how a material’s chemical elements are placed across its surface, and how they may change in response to corrosion or aging. “Much like a map of a city, which tells you where parks and buildings are, and how big, my map shows a very accurate distribution of chemicals in a material,” he says. Situm plans to extend the technique’s applications to study the stability of ceramics used to store nuclear waste, using a simulated nuclear fuel.

The research project was funded by a Canadian federal government agency; the International Minerals Innovation Institute (Saskatoon, Saskatchewan, Canada); three potash companies; and Mitacs, a national nonprofit organization for business and academia in Canada.

Source: University of Saskatchewan,