This parking garage experienced deterioration due to chloride-induced corrosion. The post-tensioned structure had been compromised and the expected service life reduced. WDP proposed an innovative restoration strategy using a multiple layer epoxy overlay system to limit further chloride ingress. The system had been applied extensively to bridge decks but had no known application on a parking structure.

WDP evaluated epoxy materials and designed a prototype installation complete with performance testing to evaluate bond, chloride penetration resistance and surface texture features. Based on the success of the prototype installation, the system was approved for the project.

The construction sequence was planned to minimize disruption of the facility. WDP provided full time Construction Management and Quality Control Monitoring. The project was completed over a twelve (12) week construction schedule at a construction cost of $1,100,000.

Also, the terrace level of this parking structure experienced significant leakage since its construction in the early 1980's. The focus of the investigation by WDP was to assess the impact of the observed leakage on the integrity of the post-tensioning system.  To evaluate the corrosion activity, both nondestructive and visual methods were used.  Locations of tests were selected to correspond with the most corrosion-susceptible areas.  Testing results did not indicate widespread corrosion of the post-tensioning system; however, evidence of mild reinforcing steel corrosion was observed.  Post-tensioning components removed during the investigation were found to be largely free of corrosion products. 

The immediate replacement of the terrace level waterproofing system was not warranted. A program of proactive corrosion monitoring allowed for the repairs to be executed in a timely manner consistent with sound economic and engineering principles.  This option of ongoing corrosion monitoring provided the Owner with significantly lower life cycle costs compared to other options.

Services WDP used on this project included:

• Structural Condition Survey
• Post-Tensioning System Evaluation
• Material Evaluation and Prototype Testing
• Rapid Chloride Permeability Testing
• Production Of Design Documents
• Bid Solicitation
• Construction Management
• Quality Control Monitoring 
• Evaluation of Waterproofing System
• Corrosion Evaluation
• Life Cycle Cost Evaluation of Repair Options
• Continued Performance Monitoring