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Photo essay: Pouring the deck for the Fillmore/I-25 interchange's new south bridge

       A layer of plastic-topped sheets was all that passersby could see the morning of Aug. 5 atop the new Fillmore/I-25 south bridge.
       Hidden as a result were the efforts of about 35 workers from project contractor SEMA Construction, who had spent the night pouring and smoothing about 35 mixing truck's worth of cement onto the recently erected span over thousands of pounds of criss-crossing rebar.
       The sheets even hid their own usefulness, in that their undersides, the parts touching the new cement, consisted of water-soaked burlap that's meant to keep the cement from drying too quickly and adversely affecting its stability.
       After about a week, the bags will come off, and roughly by September, project officials expect that cars will be able to drive on the new surface.
       The overnight job was the most recent milestone in the $15.1 million Fillmore interchange replacement project. Construction started last February. Completion is anticipated in the summer of 2016.
       The deck pour required shutting down, for most of the night, the existing Fillmore bridge as well as the interstate (although through traffic could bypass the project area via the ramps). Crews had sealed the underside of the superstructure beforehand, but the interstate had to close when the pour was above the travel lanes. That's because 100 percent certainty does not exist in such jobs that no wet cement will drip onto the roadway below.
       Westside Pioneer Editor Kenyon Jordan took photos from about 10 p.m. to midnight. Representative shots with captions appear below.
       Note: Facts for this article came mainly from answers to on-site questions of Ted Tjerandsen (pronounced CHAIR-and-sen) of Wilson & Company, the project consultant for the Colorado Department of Transportation (CDOT).
       To see the Pioneer's previous photo essay on the placing of the new girders at Fillmore/I-25 July 12, click this link.
Standing on the superstructure of the new Fillmore/I-25 south bridge the night of Aug. 4, SEMA workers spread and smooth the freshly poured cement, in conjunction with a concrete pumper and a concrete-finishing screed. The pumper is the narrow, orangish-red equipment rising up at left and coming down at right. Its fuller size can be seen in photos below. Two pumpers were used in the project, one at either end of the bridge, with long booms stretching across, and the cement pouring out of hoses that workers could move around to direct the flow over the green-colored rebar. The pumpers were connected to a series of cement mixers that arrived full and departed empty (about 35 trucks in all) throughout the night. The screed, equipped with leveling attachments controlled by an operator on top, is the large yellow device. "Bidwell" is the name of the manufacturer. Weighing about 5 tons, the machine spans the distance between the sides of the bridge. Earlier, crews had installed rails on either side - allowing it to move along them the length of the bridge. A crane then lifted the screed onto the rails the afternoon of Aug. 4. After that, the workers went home to rest up for the overnight pour.
LEFT: A waning moon adds natural light to the generator-driven illumination of the bridge project in an east-facing view Aug. 4, shortly before midnight. RIGHT: Two SEMA workers direct the flow of cement from the pumper.
Attached to a concrete pumper at right, one of the roughly 35 cement mixers sits at the east end of the new south bridge as it is emptied during the deck pour.
LEFT: In a west-looking view, workers next to the yellow concrete-finishing screed spread and smooth cement for the new south bridge. Walking along the old bridge (just to the north), an inspector watches the operation. RIGHT: It's hot work spreading cement on a bridge, but there's nowhere to get hydrated. Standing on the old bridge, Josť Acuna of SEMA tosses a water bottle across to a grateful co-worker.
Both concrete pumpers, one at either end of the new south bridge rise into the night sky in this view from the east side of I-25. At the time, only the east-side pumper was in use because the pour started from that end. Midway through the night, when the westward-moving screed passed the mid-point of the bridge, the pumper on the west began supplying the concrete.
Over an hour after the concrete was poured and leveled, a SEMA employee sprays a special chemical substance that will help "cure" the concrete to ensure a solid result. This is occurring as new cement continues to be poured in front of the finishing screed (at right), which is moving from east to west across the new bridge.
Mechanical equipment is invaluable on bridge projects, but humans are too, as indicated by a worker stretching his smoothing tool underneath the big yellow finishing screed and along the edge. This was a common activity during the operation. Note at right another worker coming over to help.
The next morning (Aug. 5), a SEMA crew finishes the job of wetting the burlap on the underside of plastic-coated sheets and placing them over the cement that was poured the night before. At this point, the bridge cement is hard enough to walk on, but it will be two weeks or more before it can be driven on. The sheets will be left on about a week, helping regulate the curing process.

Westside Pioneer article and photos
(Posted 8/5/15; Transportation: Fillmore/I-25)

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