Courtesy of Blastrac Global
Tittarelli Inc. recently completed the resurfacing of Bernard F. Dickman Bridge in St. Louis using Blastrac Global's largest shot blasting system, the Blastrac 2-4800DH.
More commonly known as the Poplar Street Bridge, the bridge crosses the Mississippi River linking St. Louis, Mo., with East St. Louis, Ill. More than 120,000 vehicles use the bridge daily, so the project's success relied on completing it in a time-sensitive manner.
The job called for the removal of 1/4-inch to 3/8-inch thick T-48 low modulas polysulfide epoxy overlay with a broadcast aggregate. Over time, the epoxy and broadcast mix deteriorated, wore and flaked away, and a new overlay of epoxy slurry and broadcast aggregate was needed to make the bridge safe for the high volume of traffic crossing the bridge.
Preparation of the steel girder bridge for a new overlay consisted of five steps: milling, sweeping, heating and scraping, sweeping again, and shot blasting. The shot blasting portion of the retexturing job was performed by four 2-4800DHs, one owned by Tittarelli Inc., one machine owned by Venture and two machines owned by Surface Preparation Inc.
In all, the project covered 280,000 square feet. Crews began their work in early June with a Sept. 1 deadline and completed the work in early August. They worked six days a week for about eight to 10 hours daily on the project. Not only did the 2-4800s remove the existing coating from the steel bridge, but, according to President Dino Tittarelli, their profiling capability increased the surface area and created an anchor profile in the steel for maximum bond strength and durability of the new coating.
Tittarelli said the company has owned a 2-4800 for five years and used the machine on various projects throughout the United States from bridges and tunnels to airport runways. He said the 2-4800's speed and coverage were crucial in completing the Dickman Bridge project on time. Another benefit of the machine, he said, is its versatility for large and small jobs.
"Right now I've got a 5,000-square-foot job and a 10,000-square-foot job to do with the 2-4800. The machine can handle these small jobs just as it can handle large projects like airport runways and the Dickman Bridge," Tittarelli said.
"It's good for every purpose, big or small whereas some equipment is so large that it can only do runway work. These other large machines won't get the job done on bridges," Tittarelli added.
According to the manufacturer, the Blastrac 2-4800DH Shot Blasting System is designed for preparation of large concrete and steel surfaces such as highways, airport runways, bridge decks, and ship decks. With a travel speed of up to 350 feet per minute and a 48-inch blast pattern, the 2-4800DH can strip, clean and profile up to 30,000 square feet of concrete, 40,000 square feet of asphalt, or 7,500 square feet of steel per hour. The machine's blast head adjusts side-to-side to allow blasting close to obstructions on either side of the machine for flexibility in tight areas and single lane closures. The 2-4800DH is powered by a 350-horsepower diesel engine and uses twin centrifugal blast wheels to propel blast media in a controlled pattern and direction. Media is recycled for reuse, while an onboard 3,500-cfm dust collector gathers dust and debris.