1 day cure concrete 2

[canwesteng]

Does anyone have any experience using concrete with a one day cure time? I'm aware of the use of high early strength concrete for three day cures, but one day seems a little quick in my experience. If we were to go one day strength of 35 MPa (say using high early strength concrete with a 70 MPa 3 day or whatever the plant decides on), are there issues with letting the concrete cure only one day? I would expect substantial cracking because the concrete must be releasing lots of heat

 

[jayrod12]

I know some of the plants around here give a 24 hour 50MPa mix for street work.

 

[SlideRuleEra]

At one of our generating stations, the concrete chimney shell was jump formed. A vertical lift could be placed every day in warm weather (on top of 1 day old concrete), or every 2 days in cooler conditions. As I recall, the criteria for the next lift was that the 1 day old concrete had to be 500 psi. This was special construction, with the jump forms specifically designed to be supported from a lower level in the chimney shell by concrete was a few days old.

If there is no reinforcing steel, we used calcium chloride in concrete to encase polyethylene pipe under public highway crossings and reopen the highway the same day.

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[hokie66]

I think expecting 35 MPa in a day is too much. Why could you possibly want that much?

SRE, 35 MPa is about 5000 psi.

 

[SlideRuleEra]

Thanks, hokie. I agree, don't expect that strength at 1 day.

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[cvg]

it is definitely possible, up to 7,700 psi in 24-hours for 4x4 mix.

http://www.virginiadot.org/business/resources/bu-mat-05vcc-rmeyer.pdf

http://www.ce.memphis.edu/1101/notes/concrete/PCA_manual/Chap17.pdf

https://www.dot.state.oh.us/Divisions/ConstructionMgt/Materials/In House Research/HESCO.pdf

 

[MrHershey]

Not really required for strength reasons, but in tunnel form construction cure times of 24 hours or even less are pretty standard. We'll usually give them a minimum strength they need for the slabs (usually comes out to like 3000 psi/20 MPa since spans are small) and they'll pour something strong enough to get that in a day or less for both slabs and walls, which are poured together. Haven't had any issues. Never specified (or needed) anything close to 70 MPa for that situation though. Agree that the heat for something that strong could be problematic.

 

[TehMightyEngineer]

In our plant we hit 5-6 ksi in 24 hour or less. No issues with hitting the strength that fast so far but being precast we will have less issues with plastic shrinkage and can control the temperature. For cast-in-place it seems very likely you could get an excessively hot piece during the cure if it wasn't carefully monitored and controlled.

Professional and Structural Engineer (ME, NH)
American Concrete Industries

http://www.americanconcrete.com

 

[robyengIT]

In a prestressed pipe factory in Portugal (pipe manufacture according to EN 642 or AWWA C301) wrapping around the pipe is done after one day usually because the concrete strength is more than 30 MPa (the standard says more than 27 MPa)
Natural process of hardening, without steam

 

[JStephen]

Sliderule, you just reminded me of this video which I ran across a while back:

https://www.youtube.com/watch?v=-ZN86lo3_20

 

[SlideRuleEra]

JStephen - Thanks for that link, its a great summary of the accident. I remember when it happened. Three years later, 1981, we (electric utility) were preparing to award the contract for the 600 ft. chimney at a new generating station. Before contract award, I met with counterparts from both our consultants (Burns & Roe) and the specialty design build contractor (Pullman). We had a frank discussion about changes made to jump form procedures since Willow Island:

Scaffolding and form supports were anchored further down the chimney shell (in concrete several days old, instead of the one day old concrete at the time of the accident).

Numerous concrete cylinders were taken for each lift, and were tested daily. We had a fully equipped on-site test lab to support all concrete activities for the entire plant construction. My recollection of 500 psi for the one day old concrete (see my post above) is surely flawed, must have been higher.

Those changes, plus the fact that SC is warmer than WV, convinced us to proceed with the award. There were no problems.

In the video, I was surprised to see Mr. Velivasakie, of LZA. He worked with us on our own corporate office building construction fiasco investigation in 1990.

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[Ron]

Canwesteng...concretes with a strength gAin that fast usually have calcium sulphoaluminates rather than plain Portland cement. Check the durability of such for your application.