Big Creek Bridge
The Highway runs along the Pacific coastline with stunning views of the ocean, and the Big Creek Bridge is worthy of its location. It’s not surprising that this gorgeous bridge is one of the most photographed in the country. The two-lane spandrel arch bridge spans Big Creek Canyon 85 feet above the ground. It’s 580 feet long, 24 feet wide and was constructed in 1937.
The Problem
The bridge's location means it is constantly exposed to airborne salts from the seawater, which are elements that are especially hard on rebar within the concrete. A corrosion survey conducted in 2014 determined that maintenance was needed. Caltrans' top priority was to breathe new life into the bridge while preserving the original look and design. They required a non-destructive treatment that will stop the corrosion. Fortunately, this is our specialty.
Our Solution
There are many ways to protect bridges from corrosion, but most options fail to preserve the look of the bridge. Electrochemical Chloride Extraction (ECE) is a specialized technique that involves temporarily applying a DC current to the reinforcing steel in the concrete. The electrical current draws the chloride ions away from the steel towards the surface of the concrete while boosting the pH of the concrete around the steel. The ECE treatment repassivates the reinforcing steel and returns it to a non-corroding state, like turning back the clock on corrosion.
The Result
The ECE treatment of the arches, spandrel columns, struts, and piers on the Big Creek Bridge was successful and will extend the useful service life of the structure. The treated area was 54,556 sq. feet and the post-treatment chloride concentrations averaged 138 PPM at the level of the rebar, which is below the threshold for corrosion in addition to the increase in alkalinity which occurs as a result of performing ECE.
Based on the data obtained before and after the treatment, it can be concluded that the Electrochemical Chloride Extraction treatment was successful in treating all zones of Big Creek Bridge.
Project Challenges
This project experienced an astounding set of challenges and conditions:
- The COVID-19 pandemic had just been declared as the project started.
- Endangered species were discovered and required special care.
- Record-setting thunderstorms ignited wildfires nearby resulting in road closures and air quality issues.
- A wicked winter storm ripped away enclosures.
- A flash flood damaged scaffolding.
- Another storm created a mudslide washing away the North highway leading to the job site and just a few days later the southbound lane started to sluff off into the ocean only half of a mile south of the bridge.
To read more about the apocalyptic conditions click here.
Technology Used
These innovative products and technologies were used on this project.