Cargill Salt has been one of the world’s leading marketers of salt products since 1962. They operate a salt storage and packaging facility south of Minneapolis, MN, on the Minnesota River, which has several monolithic concrete domes and other site infrastructure.

After years of salt exposure, the domes required rehabilitation to preserve and extend thier useful service life for an additional 30 years. The facility operates 24/7, and it was a priority to minimize disruption during rehabilitation. An assessment of the domes included:

• A review of existing documents
• Interviews with maintenance personnel
• Avisual assessment
• A corrosion potential survey
• Chloride, carbonation and strength sampling
• An evaluation of the post-tension tendons
• A LIDAR survey to make digital 3D representations of the dome

A repair and strengthening design was used for rehabilitation of the dome. It included repair of spalled and delaminated concrete using technical guidelines from ICRI 310.R-2008, removal of conveyor loads and skylights, epoxy injection of large vertical cracks, strengthening of the top of the dome using glass fiber reinforced polymer (GFRP), and removal and replacement of post-tension tendons.

In addition to this design an implementation of a corrosion management plan to mitigate on-going corrosion risk, it was also necessary to meet the 30-year service life extension objective. The corrosion mitigation plan included the following:

• Discrete galvanic anodes
• Distributed alkali-activated galvanic anode strips
• Surface-applied zinc anode sheets

The International Concrete Repair Institute recognized the project with a 2020 Award of Excellence in the Repair of Special Projects.