Curing Time in Winter
Curing Time in Winter
(OP)
I am looking at a foundation wall, about to be poured in winter weather. What percentage of concrete strength is considered adequate, to continue on with the work and add some additional dead load.





RE: Curing Time in Winter
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Curing Time in Winter
RE: Curing Time in Winter
RE: Curing Time in Winter
Contractor naturally wants to pull blankets and forms after 3 days. While I would like 7 days, the cylinders will stay out there and have to pass. If they fail, I will have them take cores to verify. My thinking on this is that the main concern is initial concrete failure in the first few days.
After that, the concrete can take all the times it needs to reach strength. And better weather is forecast for next week.
(Even getting them to use blankets caused a rucus. One sub was fired for refusing to use blankets, and came back to pull 80% of his in-place rebar out. Police were needed to stop the mayhem - I missed it)
On another project, specs call for 4500 psi and results now after 30 days are 3000 psi. Concrete supplier has pulled his computer tickets for the loads, and sees nothing wrong.
Any thoughts. GC plans to core every week to see if strength improves with time. This work was poured a month ago or so when weather was fine. Flyash was used in the mix. What are the pluses and minus's of flyash
RE: Curing Time in Winter
RE: Curing Time in Winter
Why was the fly ash specified and what class is it?
For cold weather concreting, increasing cement content and use of a non-chloride water-reducing and accelerating admixture (ASTM Type E) is not a bad idea ...if you want early strength.
RE: Curing Time in Winter
Do not use fly ash in cold weather. It does not give you any heat from the hydration reactions. But use it to keep the concrete cooler in July-Aug.
What are you going to do about the project with the low test concrete?
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Curing Time in Winter
RE: Curing Time in Winter
According to our code of practice, you may also use heaters, that does not exclude blankets, but there are mainly 2 ways to deal this problem:
1. preserving the hydration heat;
2. heating the element.
I personaly use the both, but, be carefull for the possible cracks that might appear. DO NOT EXCEED A DIFFERENCE OF 40 degrees between the heated element and the environment.
Good luck!
Catalin Dumitrescu,
Bellinghausen Beton SRL
Romania
RE: Curing Time in Winter
Richard A. Cornelius, P.E.
WWW.amlinereast.com