Deck poured for second half of interstate bridge over Cimarron
A major milestone in that process took place overnight June 13. About 100 workers labored for close to nine and a half hours straight to pour 440 cubic yards of cement for a segment 71 feet wide and nearly 400 feet long. The future driving surface will handle the right-hand lanes on the bridge's northbound side.
The job was part of the $113-million Cimarron/I-25 interchange replacement by contractor Kraemer North America, in concert with the Colorado Department of Transportation (CDOT). The project started in May 2015 and is due for overall completion by December.
The bridge's full deck width will be 151 feet, capable of carrying three lanes of traffic each way. The first 80 feet were completed just west of the 71-foot width last September. Up till then, traffic was still using the old bridge (built about 1960 to handle two lanes each way).
The new bridge's full width couldn't all be built at once because of the need to keep freeway lanes open to traffic while work continues, project officials have explained.
So once that first new segment went in, traffic both ways was redirected to it from the old bridge, which was then torn down. The 71-footer was built almost on top of where the old one had been.
The overnight work June 13 lasted from about 9:30 p.m. to 7 a.m., according to Don Garcia, deputy project manager with CDOT consultant Wilson & Company.
Cimarron Street under the bridge was closed for the night, with motorists detoured around it.
The concrete was delivered to the deck through an arrangement of connected pipes from a large pumping machine sitting on the street below, which in turn was being fed by mixer trucks driven in, one after the other. On the deck, the pumped cement gushed out through a heavy-duty, roughly six-inch-diameter hose held by a worker.
The goal was to distribute the product to a depth of 9˝ inches under and over a cross-hatch of 3/4-inch rebar. Helping with this process were fellow workers with shovels, leveling tools, vibrating rods (to make sure the concrete got into all the nooks and crannies) and water sprayers (to keep the stuff from drying too fast). Mechanical leveling was provided by a "screed" attached to the underside of the width-spanning Bidwell device (see photo at bottom).
Before the concrete was pumped up to the deck, its quality had to be tested twice - first by the contractor and then by CDOT. It's not that uncommon for a whole mixer load to be rejected, Garcia noted.
Kraemer crews had set 18 bridge girders in early April to begin shaping the final “half.” The concrete poured for the deck June 13 will need several weeks to cure, with late July anticipated for the opening, Garcia said.
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