Revive Wacker Drive, a multimillion-dollar infrastructure reconstruction project in downtown Chicago, is set to see completion in fall 2012. On Friday, August 26, 2011, the fourth concrete deck pour of the second phase was completed; five more deck pours and one ramp pour remain.
This post-tensioned concrete deck pour was for a section of the project 229 ft long by 120 ft wide, running south to north in the mid-block between Madison Street and Washington Street. It used 146 trucks’ worth of high-strength, high-performance concrete and took about nine hours.
“It’s hard to visualize now, but there will be three lanes of traffic and a sidewalk area,” said Clifford Olszewski, P.E., senior construction manager. “After the deck gets poured, we’ll add the sidewalk or public right-away, and then a planter in the middle of the street that will be landscaped.”
The pour consisted of 1,311 cubic yards of concrete, using two 85 m concrete pumps working in tandem. The largest pour was the third in the series, at the intersection of Washington Street and Wacker Drive, and comprised 1,700 cubic yards of concrete. The first pour comprised 1,200 cubic yards of concrete at the Randolph Street and Wacker Drive intersection and the second was 1,400 cubic yards of concrete at the Wacker Drive mid-block between Randolph Street and Washington Street.
After the concrete was poured, it underwent seven continuous days of wet cure, using a layer of cotton mat blankets covered by a layer of plastic sheeting and kept saturated by a continuous supply of water through soaker hoses.
After the concrete is poured, cured and post-tensioned to make it less susceptible to cracking, a 2 in. latex overlay will be placed atop the concrete.
“We use a latex-modified concrete-wearing surface that is less permeable to salts and water to provide additional protection of the structural bridge deck,” Olszewski said.