How long does it take for concrete to cure?

[daddo]

When the concrete railroad bridge was damaged here a few years ago, they had a new one made and we had to wait 28 days.

I was always told that it gains it's best strength in 50 years at 6" thick- give or take a few minutes.

But I was also always told candy caused pimples and that I should be blind by now.

[woodhead]

I know that if you let concrete dry too quickly it compromises the strength.

The county poured a new road surface for a small bridge near my house.  They covered it with plastic sheets and have a water sprinkler system mist over the sheets 24/7.

It's been "drying" for over 2 weeks now.  

Is there a legitimate reason for such a long cure time or are they padding the work to extract extra money from the county?

State work usually requires all forms to be in place for 21 days...aides in curing.  



Al

[fishhh4]

7 days is the norm for wet burlap on bridge deck .Triple A concrete which is cement rich . The reaction gets hot . Best to keep it cool ....wet . Other wise you get spider cracks all through it .

[EricU]

I think the world's record may be the bridge on a forestry road near here.  They replaced a culvert with a short span concrete bridge, and it was out for months.  First they  made the bridge, then they came back for the railings.  On the other end of the scale, they replaced a bridge on the main drag through town, and it was back up in less than a week after the last span was replaced.  They must have used precast on that one, but I didn't observe the details.

People may whine about Gov. Drillbit raising gas taxes 30 cents a gallon, but they are definitely replacing all the old bridges.

[fishhh4]

One of the largest government  contracts ever  was let to Walsh construction out of Chicago ( so I heard ) . 500 mostly rural bridges thru out the northeast . Two of them are within 5 miles of me .

Here it is ... looks like just Pa.

[FloridaRetiree]

I read somewhere that the core portions of the Hoover Dam concrete is still curing, 80 years later . . . .

For anyone who has never been to and gone down into the Hoover Dam you should do so if you get the chance. 

Another awesome engineering marvel; and, as I remember, one of the longest continuous concrete pours.




 http://aeweb.tamu.edu/whit/Classes/214_W...ncrete.htm

[Cooler]

It is four weeks since they poured the concrete and the tarps and water sprinklers are gone.  Also gone are the Jersey barriers.  The westbound lane is still closed so they have retained the traffic control lights for the time being.

The asphalt trucks were lined up this morning so I hope that they are repaving the transition between the roadway and the newly poured concrete bridge.

The red light takes a full four minutes to change and the traffic backs up so much that sometimes you cannot get over the bridge on one light change.  I have to leave for work 20 minutes early just to be sure to arrive on time.

I will be glad when this is over.