What steps are needed to prepare existing concrete for using FRP? What about cases where the rebar has corroded due to water infiltration and some of the surface concrete has popped off?

All existing cracked and spalled concrete must be removed and the substrate repaired using appropriate concrete repair materials. Then, the surface is prepared and FRP can be installed.

The design of the FRP can be based on restoring the original (or required) strength of the structural components. This can be done by measuring the residual cross sectional area of the steel bars after cleaning to remove rust or corrosion byproducts. If the member contains high level of chloride, a corrosion protection system may be required to protect the existing steel bars and prevent further deterioration. This should be done prior to FRP installation.