Mission Hills, San Fransisco Valley, CA
What Caused The Problem
Cracks in the concrete allowed moisture to get to the post–tension cables. This lead to significant corrosion damage, so bad that they had to abandon the structural capacity and install a complete structural system below.
The new structural system includes sister columns to support the significant additional load no longer carried by the post-tension cables. Large steel beams were also included and were mounted and grouted using SikaGrout 328 and SikaGrout 212. In addition, small steel strips were anchored in place and grouted with Sikadur 31 Hi-Mod epoxy adhesive to span the gaps between the new sister columns and large steel beams.
To help mitigate additional corrosion damage and add structural integrity to the newly reinforced concrete deck, cracks were injected with a low viscosity epoxy, Sikadur 52.
Lastly, the top deck was coated with an elastomeric urethane traffic coating consisting of Sikalastic 720 SG base coat and Sikalastic 745 top coat to protect the deck from additional chloride penetration.