Concrete deterioration can be a major problem for facilities managers anywhere, but it’s especially challenging to address when a facility needs to remain in operation during repairs.
A Terracon client in the amusement park industry approached Facilities services staff with a heavily deteriorated elevated concrete slab project, and specific expectations for the repair program results.
The slab was located within a swimming pool equipment building and had been exposed to moisture and pool sanitizing chemicals for an extended period of time. Terracon’s investigation showed there were locations on the slab with a soluble chloride ion content in the concrete that was well over the 0.15% maximum requirement for concrete exposed to moisture and external sources of chlorides.
Two types of concrete compressive strength tests were performed: drill core testing and rebound hammer for hardened concrete. The concrete compressive strength was tested and found to be acceptable and suitable for a slab rehabilitation. The initial project requirements were to restore the slab while the pool equipment remained in operation and portions of the space remained in use, and the repair design should add 10 years of service life to the slab.
The design process included several iterations. Initially, the client received a budget for a repair program that consisted in concrete repair, steel replacement, and waterproofing of the slab. Then, the client decided the project requirements for added slab life should be extended to 15 to 20 years. Challenge accepted! Our design team went back to work and proposed installing a combination of an initial intense burst of current to passivate the bar and long-term protection with the installation of internal impressed current, commonly known as galvanic anodes.
We advised our client regarding the most cost-efficient methods to achieve the desired outcome. When the client questioned our proposed technology and repair method, our facilities design team presented our research, test results, and case studies, allowing the client to further understand the proposed repair technology and benefits, allowing them to be confident in approving the project approach.
The final design met our client’s requirement to extend the life of the slab for another 15 to 20 years effectively establishing reinforcement cage continuity to enhance the effectiveness of the corrosion mitigation systems, installation of corrosion mitigation systems, concrete repair and waterproofing of the top of the slab, and concrete repair and steel replacement by means of externally applying carbon fiber polymer to the slab soffit. This combination of repair technologies and approaches met the unique project requirements and stayed within our client’s project budget.
Carla Ramo Velázquez, P.E., is a senior engineer in Terracon’s Facilities practice in Winter Park, Fla. Specializing in business development and project management of concrete restoration projects and constructions services, her experience includes management of contracts and construction activities for the private and public sectors.