Engineers at Monash University are investigating the soil surrounding buried pipelines as a possible solution for reducing corrosion and extending the lifetime of critical infrastructure.

Specifically, the Monash team looked at specially-designed backfill materials that could potentially be used as an active corrosion protection system instead of providing mechanical support.

Source: Monash University

Pipelines buried underground and composed of metallic materials tend to be vulnerable to corrosion and corrosion-related failures can cost municipalities billions annually in terms of repairs, maintenance, water loss and infrastructure replacement.

Examining how factors such as moisture, soil acidity, salt concentration, electrical resistivity and compaction encourage the corrosion of buried ductile iron pipelines, the team suggests that the structural performance of backfill materials could potentially offer a solution despite the surrounding soil environment playing a major role in corrosion rates.

"Protective coatings and cathodic protection systems remain important, but their effectiveness is strongly influenced by the surrounding soil conditions," the team said. "Our work shows backfill should be treated as part of the corrosion protection strategy itself, not just material used to support the pipe."

Looking specifically at new resistive backfill materials, construction methods and modeling techniques designed to minimize corrosion across entire pipeline networks — including interference effects between adjacent buried pipes in congested urban environments — the team believes their new backfill approach could offer a less expensive path for improving the longevity of infrastructure while simultaneously reducing maintenance demands as well as the carbon footprint associated with replacing aging underground assets.

"Corrosion is often treated as a separate issue from geotechnical engineering, but these systems are deeply interconnected," the researchers said. "This research highlights the need for more integrated infrastructure design approaches that consider both structural performance and long-term corrosion resistance."

The findings are detailed in the article, “Sustainable Backfill Design Strategies for Mitigating External Corrosion in Buried Ductile Iron Pipelines,” which appears in the journal Geotechnical and Geological Engineering.