The in basket: Perry East writes, “I recall several years the much-touted latex asphalt pavement over the Warren Avenue Bridge (in Bremerton) was the cure-all. How has it been holding up?”
The out basket: Chris Keegan, the Olympic Region’s bridge expert for the state, says the patches that give the bridge a troubled look really comprise less than 1 percent of the surface and the surface is holding up well.
He started with the basics.
“The overlay placed on the Warren Avenue Bridge was a polyester overlay,” he said. “It is just three-quarters of an inch thick.
“The underlying concrete deck was made with lightweight concrete. Instead of hard aggregate, i.e. rocks, they used a lightweight material. This enabled the bridge designer to design longer spans without putting more piers in the water.
“The lightweight concrete does not wear well so the design included an asphalt wearing course. The asphalt wearing course was removed and the thin polyester overlay placed on the deck. This was done, I believe, in 1992.
“One of the reasons for the polyester overlay,” Chris said, “is that it would last longer than asphalt. This was one of the first uses of the polyester overlay in the state and we had problems with the material setting up. In some cases it just did not get hard. We were in patching the deck soon after the contract.
“The deck area of the Warren Avenue Bridge is 94,435 square feet. The patched area after 18 years is 567 square feet, or about half of 1 percent. The other 99.5 percent of the deck is in good condition. Despite a rough start, the polyester overlay is holding up well.”
Polyester overlays have been used quite extensively by the state in the last 10 years, including on I-5 for the Puyallup River bridges, he concluded.