SCDOT uses repair, strengthening materials to prevent bridge deterioration

Sept. 20, 2018

The South Carolina Department of Transportation (SCDOT) found corrosion-related deterioration of the pier caps and columns supporting the Butler Road bridge over I-385 in Greenville, S.C., during a routine inspection. The corrosion was caught early enough and was limited to only one column and a couple of locations on the pier cap to be repaired by the SCDOT maintenance crews. To prevent further deterioration, SCDOT determined it was necessary to repair the damage, restore any loss of strength and protect the pier from further deterioration. A repair that could be made quickly and with as little disruption to the traveling public was important.

Milliken Infrastructure Solutions (MIS) engineers visited the jobsite with SCDOT to assess the scope of the problem and understand the objectives of the agency. After the site visit, MIS recommended using GeoStrong geopolymer repair mortar to make the vertical and overhead spall repairs on the pier cap, followed by the application of a single layer of RenewWrap FRP strengthening system to restore any loss of strength and to protect the pier cap from further deterioration.

The work was completed by SCDOT maintenance crews in the evenings to minimize lane closures on I-385. Standard concrete repair methods were used by the department to make the repairs. Once the loose concrete was removed and the corroded rebar was cleaned, the GeoStrong geopolymer repair mortar was placed by hand to fill the spalled sections. Unfortunately, heavy rains in South Carolina forced the crew to shut down before the patching could be completed. When they returned two weeks later, they could patch directly over the cured GeoStrong material with confidence knowing that cold joints would not be a concern with the geopolymer material.

When the GeoStrong mortar was applied and cured, MIS engineers instructed the maintenance crew on how to apply RenewWrap FRP system to the pier cap and column. The carbon fibers were aligned in the same direction as the corroded reinforcing steel to provide additional strength and protection to the damaged areas. The following night, SCDOT coated the RenewWrap with a Sherwin-Williams epoxy paint to match the rest of the pier. To the traveling public, the pier looks like a brand-new structure.

The SCDOT assistant district maintenance engineer and maintenance crew commented on the ease of installing the FRP strengthening system, and hope to use this material on future maintenance applications.