Air entrained concrete Vs. Non Air entrained concrete
Air entrained concrete Vs. Non Air entrained concrete
(OP)
We specified 3500 psi non-air entrained concrete at slab on grade for a commercial project, and the GC poured 3500 psi air entrained concrete. Does it make a difference? I would appreciate your input.






RE: Air entrained concrete Vs. Non Air entrained concrete
RE: Air entrained concrete Vs. Non Air entrained concrete
RE: Air entrained concrete Vs. Non Air entrained concrete
RE: Air entrained concrete Vs. Non Air entrained concrete
RE: Air entrained concrete Vs. Non Air entrained concrete
If I remember correctly, a combination of air-entrainment and high w/c ratio would make delamination more likely; but if that hasn't occurred, you got some extra weathering protection for free.
Wouldn't worry about it.
RE: Air entrained concrete Vs. Non Air entrained concrete
If this is an interior slab, why is weathering protection a consideration?
I would think that the traffic of the machinery would be much more of a consideration for the durability of this slab than weathering, no?
RE: Air entrained concrete Vs. Non Air entrained concrete
air entrained concrete is required by the state dot (Arizona) for highway pavement and other structures where freeze thaw is of concern. It is not required in other areas, but is still allowed. there are no other requirements for durability of the concrete pavement due to heavy traffic loading.
RE: Air entrained concrete Vs. Non Air entrained concrete
dcredskins-
Is this slab interior or exterior?
RE: Air entrained concrete Vs. Non Air entrained concrete
Weathering isn't isn't a consideration. He just got it for free. I guess it's kind of like getting a free furnace here in Texas. Except you can't ebay air entrainment!
But now that you mentioned it, I think I do remember density being more important for high loading. Oh well. I still think it won't be a big deal unless he has a high percentage of air-entrainment.
RE: Air entrained concrete Vs. Non Air entrained concrete
frv, the compressive strength of used air entrained concrete is same as originally specified non air entrained concrete.
RE: Air entrained concrete Vs. Non Air entrained concrete
The fact that it's the same ultimate strength isn't really what StructuralEIT was alluding to.
Sure, if you were to put both cylinders into a compression test, they'd both do just fine.
The failure mechanism EIT is talking about, however, is due to cyclic loading. A heavy forklift won't come close to cracking the slab if it is only loaded a few times. However, each time the forklift is used, it damages the slab more than a non air-entrained slab. The micro-voids created by the air are more easily fractured than a more dense concrete.
RE: Air entrained concrete Vs. Non Air entrained concrete
With air entrainment, the bleed water in the concrete is inhibited more from coming to the surface and thus you run the risk of various degrees of air pockets formed just beneath the surface.
Depending on the mix, finish timing, etc., the pockets could be deeper or shallower and may not show up right away.
So the first order of business would be to look for delaminations. These would be found by visual inspection (looking for blister cracking), by chain drag (sounding for hollow sounds) or by coring (analysis of the cross sectional properties in the top layers of the slab).
There is also the behavior of air pockets formed from the vibration and dragging of the finishing blades during troweling, that develop air pockets even without bleed water effects.
RE: Air entrained concrete Vs. Non Air entrained concrete
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RE: Air entrained concrete Vs. Non Air entrained concrete
RE: Air entrained concrete Vs. Non Air entrained concrete
RE: Air entrained concrete Vs. Non Air entrained concrete
I have not hear of delimination problems with floor finishes but I have heard of salamder-type heaters burning natural gas inside buildings during the winter, elevating the CO2 in the building and causing spalling when the surface was too brittle to withstand normal traffic.
Don Phillips
http://worthingtonengineering.com
RE: Air entrained concrete Vs. Non Air entrained concrete
FWIW, proper sub grade prep is just as important as the concrete mix.
RE: Air entrained concrete Vs. Non Air entrained concrete
I suspect this is something that would be taken into account by the concrete supplier. That is, a normal concrete may require a certain w/c ratio to achieve f'c, but an air entrained version may require a slightly lower w/c ratio to achieve the same f'c.
RE: Air entrained concrete Vs. Non Air entrained concrete
RE: Air entrained concrete Vs. Non Air entrained concrete