Hot Weather Concreting 1

[DHKpeWI]

The spec in our office requires that the contractor keep the temperature of the concrete below 90 degrees F during placement. The building is seven story, post-tensioned concrete in central Florida.

ACI 305 limits the temperature to 95 degrees F. Can the concrete go as high as 100 degrees F? What are the concesquences?

 

[hokie66]

This is one reference, albeit from Australia. The lower the temperature, the better. Stick to your specification. In Florida, contractors should be accustomed to the methods required to control the temperature of the fresh concrete.

http://www.concrete.net.au/publications/pdf/Hot_Weather.pdf

 

[concretemasonry]

You can also check with the local ready-mix suppliers to see what procedures they use to satisfy contractors for workability and finishing of slabs. It may range from using ice to chilling the water for slabs.

The problem is the heat of hydration and rate of curing, which has been a classic problem and magnified by the mass of the placed concrete.

Fly ash will always slow the hydration rates, but it must be included in the submitted mix designs from the contractor or R/M supplier.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[derim01]

Yes, as said above, check with ready mix suppliers, they already know how to deal with it.
I am working in Middle East, temperatures are extreme, but adding ice to mixture solves the problem.

 

[DHKpeWI]

derim01:

Were you able to allow the concrete to be 100 degress F?

 

[derim01]

We have to follow the specs, and supplier is delivering ready mix below 90F. Even air temperature is above 100F.