Bridge Mimics Look of Natural Stone with Vertical Concrete Coatings

See how a plain gray concrete bridge was transformed into a work of art meant to resemble local Limestone.

Posted by admin on September 14, 2022 in Blog

Owners of Northline, a new mixed-use development in Leander, Texas, needed to construct a bridge, and they had specific wishes for the aesthetics. Rather than a plain gray bridge, they wanted it to look as if it was built using the same limestone that was used on retention walls throughout the development. Mimicking the look of actual stone on concrete is a difficult task. When it’s not done properly, it can look contrived and manufactured. But SUNDEK of Austin, a crew of skilled decorative concrete contractors, knew this was a look they could achieve for the bridge—using the right technique and product.

SUNDEK of Austin began with a blank slate: patterned gray precast concrete.

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For the project, SUNDEK of Austin suggested using SunColor, an acrylic water-based colored coating, which they would install onto the vertical concrete surface. Its durability and longevity is the perfect fit for this type of structure. The bridge extends over a pond which is a holding tank for the drainage water for the development. In other words, the bridge’s decorative coating would need to be durable and able to withstand years of water hitting it in some spots.

SUNDEK crews provided multiple mockups for the developer’s approval. “We worked with them to get as close as possible to the color of the existing limestone on site,” says Kevin Thiemer, the SUNDEK of Austin sales representative for the project. Not an easy task, as natural limestone is made up of many minerals which creates significant color variation. After several iterations, crews and the project owners decided on using a combination of five colors: Bone White, Franciscan Tan, Indian Wheat, Mission Tan, and Sable.

Crews used five colors of SUNDEK’s SunColor product to create the look of limestone: Bone White, Franciscan Tan, Indian Wheat, Mission Tan, and Sable.

The bridge, plain gray concrete, was precast in a pattern that looked like rock. With that blank slate as their canvas, SUNDEK crews—truly artists on this project—began coating the concrete with the various shades of SunColor. They strategically placed each color, layering some on top of each other, while allowing other colors to show through in just the right places. “During the project, we walked through the site with the owners of the development so they could provide feedback on the color,” Thiemer says. After making adjustments several times along the way, the crews ultimately arrived at a shade that remarkably resembled the limestone on site.

One of the biggest challenges while completing this project was the weather. “It was a battle,” remembers Thiemer. Because the bridge extends over a pond, that means they had to drain the pond to complete the work on the vertical surfaces of the bridge. Rainy days caused delays in the project as crews had to wait for the rain to pass then clear the water once again before they could continue work.

Despite the challenges of getting the color right and working around inclement weather, SUNDEK of Austin was able to take a plain gray bridge and transform it into a beautiful work of art that resembles natural limestone. To protect such a surface required a high-quality sealer. Thiemer says that the developers originally requested a general water-based clear sealer, but SUNDEK recommended a sealer with added protection: their anti-graffiti sealer. In addition to protecting the bridge from staining from things like water, dirt, and other contaminants, it also makes the structure resistant to staining from spray paint or other materials meant to deface the bridge. The sealer—the finishing touch of the project—means that even a deliberate attempt to damage the bridge with graffiti will not ruin its beauty, as it can be washed off. The result? A gorgeous bridge for residents and visitors of the development to use for years to come.