Boerentoren (KBC Tower)
In anticipation of the World Exposition coming to Belgium, Antwerp’s Boerentoren (KBC Tower) opened in 1930 and is an art deco style building built in the same style as modern skyscrapers of the time in New York and Chicago. Using steel frame construction methods allowed buildings to reach new heights compared to traditional stone construction. When complete, the tower was 87.5 meters high and considered the tallest building in Europe. The white limestone building consists of 24 floors in the tower and nine floors in the side wings and was designated as a Protected National Monument in 1981.
The Problem
After inspections in 2009 and 2010 again detected long vertical cracks near steel columns and horizontal cracks beside the beams, the engineer determined that traditional masonry repair would not solve the underlying corrosion problem on the structural steel frame.
Conclusions of the building research include:
- The masonry covering does not provide sufficient corrosion protection
- The volume of corroding steel increases by a factor of seven and damages the outer, rigid stone leading to high maintenance costs and safety concerns
- Water-repellent treatments applied in the 1990s have not been effective because the stone is highly adsorptive and is dampened by water penetration through the joints
- Previous repairs have again been damaged by corrosion. If the corrosion problem is not addressed, a durable repair is not possible
Our Solution
A conventional repair approach requires exposing the steel frame, applying a protective coating, then rebuilding the stone façade. Given the need to address corrosion in large areas of the structure, this approach is costly and disruptive. For this reason, an alternate technique of applying cathodic protection was considered.
Cathodic protection, successfully utilized to mitigate steel frame corrosion in historic structures for approximately 15 years in the United Kingdom, offers an environmentally friendly, permanent solution to mitigate existing corrosion and prevent future corrosion of the load-bearing steel frame.
The Result
The scope of work included light, general cleaning, replacing limestone affected by corrosion, moss-repellent treatment, concrete repairs, flashing repair, and downspout replacement. Impressed current cathodic protection using Ebonex® ceramic titanium dioxide anodes installed through joints in the exterior walls was provided to 25% of the structure's surface area.
The repairs were discretely completed to the historic structure, which is protected from corrosion with low voltage protective electrical current.
Technology Used
These innovative products and technologies were used on this project.