The historic Centennial Bridge connecting Rock Island, Illinois and Davenport, Iowa is the focal point for both Mississippi River communities, making it an inviting potential target for would-be graffiti artists. When a decorative gateway was added to the structure in 2006, city officials chose to protect the gateways’ concrete pillars and supports with a graffiti-resistant coating from Tnemec. “The owner wanted a durable and clear graffiti-resistant coating applied to the concrete, so that if it were to be ‘tagged,’ the graffiti could be easily removed,” according to Tnemec coating consultant Keith Kennett. “We recommended Series 626 Dur A Pell GS to provide protection from graffiti, plus outstanding water repellency.”
Dur A Pell GS is a clear, silicone rubber-based formulation, which protects vertical concrete block, brick, cast concrete, stone and other masonry substrates with little or no change to the appearance of the substrate. “The designer knows it is there, but visually it doesn’t affect the color of the concrete,” Kennett commented.
Surface preparation required the concrete to be clean and dry prior to coating application using a lowpressure sprayer. “The product was very easy to apply,” Kennett noted. “It’s not a coating that sits on top of the concrete – it actually penetrates into the capillaries of the concrete and becomes part of the substrate. For graffiti-resistance and water repellency, it provides long-lasting performance.”
Dur A Pell GS is designed to permit multiple cleanings, and is used in conjunction with Series 680 Mark A Way citrus cleaner. Unlike “sacrificial coatings” that do not chemically react with siliceous surfaces, Dur A Pell GS does not require recoating after graffiti is cleaned off. “It’s a very passive product that hopefully is never needed,” Kennett explained. “If you do need it, however, it’s worth its weight in gold.”
“Everybody is happy with the project,” Kennett added. “While we all hope the gateways are never defaced, if they are, the cities know they can remove the graffiti without impacting the existing concrete.”
The Centennial Bridge, or Rock Island Centennial Bridge, is 3,850 feet (1,173 m) long and stands 170 feet (52 m) above water level. It was named in commemoration of the city of Rock Island’s centennial.