As a leading supplier of wet fluxes, specialty fluxes and foundry products to the metal casting industry, American Metal Chemical Corporation (AMCOR) realized that the concrete walls of its salt dome were in need of repair. AMCOR mixes together salt, pot ash and miscellaneous chemicals and materials to sell to aluminum manufacturers to use in their smelting process. After a visual inspection that revealed delaminated and spalled concrete, the owner contacted Structural Preservation Systems (SPS) to perform the necessary repairs.

Upon assessing the structure, SPS determined that 75 percent of the interior wall of the salt dome was deteriorated due to corrosion from the salt. In fact, the salt had corroded the rebar and reinforcing steel so severely that concrete had begun to fall from the structure. The SPS repair team evaluated several repair strategies, including the form and pour technique, but it was determined that the formwork would be too expensive. Instead, crews utilized shotcrete, which eliminated the need for formwork.

To begin the repair project, crews pressure power-washed the interior of the structure to remove the heavy concentration of salt and residue. Then, the damaged concrete was demolished from the perimeter of the wall up to four inches in depth. The deteriorated concrete was removed until a sound substrate was reached. The team sandblasted the structure to remove corrosion on the reinforcing steel and promote a strong bond between the repair material and the substrate. Supplemental reinforcement and wire mesh were installed to replace deteriorated steel. The wire mesh was used to help the shotcrete adhere to the substrate. The reinforcing steel was supplemented with additional reinforcement in locations where the existing reinforcing steel was extremely deteriorated, and then a specialty prepackaged shotcrete repair material was placed. In addition to the 2,900 square feet of vertical concrete repairs completed, the crews performed 500 linear feet of grout and seal crack repairs on the exterior of the salt dome.

Scheduling was critical on this project because the salt dome had to remain empty during the repairs. The owner was expecting another shipment of salt, so repairs had to be completed before it arrived. The 2,900 square feet of repairs were completed in a mere five weeks to meet the owner's schedule. The owner was extremely pleased with the results of the project. The repairs restored the structure and increased the structural integrity, which should add many more years of service to the existing dome.