Construction Update: For concrete it can be too cold, too wet or, now, too HOT to pour!

Check out the view of the bridge—and traffic flow—from Erik Nicolaysen’s second floor window by clicking HERE.
July 9, 2010
by Christine Yeres

For a substance that can take so much abuse once it’s finished, concrete sure is touchy about conditions at the time it’s poured.  Last winter, the cold closed in to prevent the pour of the bridge deck, which needs about a month of temperatures of 40 degrees or above in order to cure properly.

Conditions have to be dry, of course, since adding water to concrete diminishes its final strength, yet too little water will cause it to dry too fast and crack.

This week, temperatures were too high to mix concrete; they would have caused the concrete, once poured, to dry too fast and crack.

The yellow bridge-like structure that is poised across the bridge deck is a “finishing machine,” suspended above the deck surface by legs on wheels alongside the roadbed. Without “stepping” on the concrete, the finisher will run across the poured concrete from above, smoothing it, imparting a pitch to the roadbed (for future drainage of rainwater) and vibrating entrapped air out of the concrete.

The pour is on for next week, weather permitting.

Two views of The Finisher: