Tarlton updates iconic bridge with wood-like precast deck

St. Louis-based Tarlton Corp. received the 2017 Quality Concrete Award from the Concrete Council of St. Louis and American Steel Fabrication for its concrete transformation of the original wooden bridge that connects a main walking path through the Missouri Botanical Garden’s Climatron.

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Raineri Ready Mix used Solomon Colors Inc.’s 338 Leather pigment to achieve the wood color in the precast deck concrete mix. PHOTOS: Tarlton Corp.

The general contracting and construction management firm replaced the existing 28-ft.-long timber bridge deck with precast planks welded to the existing steel girders. The concrete was cast into 28 pieces, each 12-in. wide x 8-ft. long x 4-in. thick with a wood-grain texture to mimic timber planks. Using the precast planks in lieu of a cast-in-place deck allowed the existing decorative fiberglass wraps on the girders to remain in place and cut the duration of construction in half—to less than two weeks.

Tarlton turned to St. Louis-based Raineri Ready Mix, who completed renovations to the Climatron nearly 30 years ago, to develop the mix and colors for the planks. After only a couple test pours of the specially blended mix and colors, the desired detail was achieved. “The precast molds were made of standard handset forms lined with an architectural wood grain rubber stamp,” explains Brian Shaffer, Tarlton Concrete project manager. “The variation of the color settling into the various niches of the rubber stamp truly replicated the color and texture of real wood.”

According to the Missouri Botanical Garden, the term “Climatron” was coined to emphasize the climate-control technology of the iconic greenhouse dome, which was designed to offer consistent levels of humidity to accommodate an extensive collection of plants, including many rare and exotic species. Shaffer notes that these conditions were ideal for curing the new concrete work.

Tarlton also began a second project at the Missouri Botanical Garden this year, serving as construction manager for the renovation and addition to the 7,000-sq.-ft. Stephen and Peter Sachs Museum, due for completion next spring.