SOLUTION

To repair the exterior historic concrete walls of the stage structures, the existing coating was removed and the historic concrete was repaired with custom pre-bagged repair material developed to match the original concrete. To match the range of original concrete composition, two different custom mixes were selected.

Especially challenging was consideration of whether to recoat the historic concrete. Although pigmented, film-forming coatings had been applied in the past, once the existing coatings were removed, the varied appearance of the original concrete was appreciated. At the request of the client, WJE evaluated and considered a range of coating systems and provided a comparative assessment of all options—including the option of leaving the original concrete exposed after cleaning. This option, the most desirable with respect to the Secretary of the Interior's Standards for the Treatment of Historic Properties, was found to be viable after successful implementation of concrete repair mock-ups and was eventually selected by the project team.

The coating removal and concrete repair mock-up process took place over a period of two months. After several repair approaches were evaluated, four different coating removal systems and six different concrete repair materials were evaluated. Repairs were then implemented using knowledge gained through the extensive mock-ups.