Freeze/thaw protection of non-air entrained concrete during construction after achieving strength

[cliff234]

Concrete exposed to freeze/thaw is air entrained. We do not air entrain concrete in floor slabs that are not exposed to freeze/thaw. A question came up in our office about what precautions, if any, need to be taken during construction to protect non-air entrained floor slabs that have achieved their design strength, but which still might be saturated and exposed to freeze/thaw during construction (prior to the structure being enclosed). I can’t find any guidelines or recommendations. Is this a valid concern? Has anyone ever heard of freeze/thaw damage occurring to non-air entrained concrete during construction after the concrete reached its design strength?

ACI 306 (Guideline to Cold Weather Concreting) only deals with protection of concrete in cold weather before design strength is achieved.

 

[jayrod12]

Generally speaking, one construction years worth of thermal cycling will not affect the long term durability of the slab. Most codes, my local one specifically, give exceptions to the freeze-thaw rule for certain items like hockey rink slabs. They need to be baby-bum smooth so you can't have air, but they're frozen. From experience it has been determined that the one freeze and one thaw cycle that the rink slab is going to see each year will not affect the long term durability.

However, air entrainment (at least where I practice) may be added to many mixes not directly exposed to freeze thaw, but exposed to other harmful elements.

 

[r13]

Concrete takes long time to dry out, even the strength has been achieved, the remaining pore water may still subject to freeze and thaw condition, and causing problems to occur. I suggest to explore methods to cover it up, before it is enclosed in a controlled environment, temperature-wise.

 

[structSU10]

ACI 306 states concrete below 3500 psi may be damaged by freeze thaw cycles, and can go down to 500 psi if it is air entrained. I have not seen commentary on the number of cycles that are acceptable.

 

[wohoodiii]

As long as the contractor doesn't spread deicers on the non-air entrained concrete it should be fine. Use sand for traction on localized pathways across the slab.