I don't know of a specific rule but, if your wall concrete is exposed to freezing and thawing, air entrainment seems wise. How does the painting factor into things? Unless you're confident that the paint could somehow serve insulating / vapor barrier functions, I wouldn't think that it would help in this regard.
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Are you referring to site cast panels or plant produced panels the could be extruded and cut to length?
If they are site cast, the responsibility is on the designer and contractor.
If plant produced (extruded) the concrete is a different type and has different properties based on histories and manufacturers specifications. - Architectural and sandwich (lightweight/normal weight, normal weight, insulated) panels are usually well documented, but the configurations go well beyond the classical air test like normal concrete.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
Plant produced is usually quite different from site cast concrete, up to and including steam and pressure produced concretes similar to the production of CMU blocks.
The simplistic general range of the concrete type materials used is:
1) "Normal" wet cast concrete that is placed and finished by hand in individual sections that can even be cast on top of each other for use as floor panels or opposite the desired placement site. Also for some architectural panels cast in a plant under controlled conditions with or without accelerated curing.
2). "Low slump" concrete is often extruded in a plant setting for controlled vibration/densifying and uses accelerated/controlled curing to provide maximum production and fast handling properties.
3). "Zero slump" concrete is exclusively for plant applications that provide uniform,predictable properties. This is common for smaller size materials such as small wet cast items, lintels and concrete block. For plants that run 24/7, cured materials for construction can be available for use range from 8 hours to 24 hours. Concrete block with a compressive strength of well over 8000 psi (net unit compressive strength) and 6 hours of curing are possible. Obviously, the fast time is not always critical since the production rate is much higher than the daily demand rate.
Some of the more unique "cement" based products are AAC (Autoclaved Aerated Concrete) that utilize costly equipment and "exotic" material combinations. - Sort of like making bread, allowing it to rise before and during the curing cycle and then cutting to desired sizes. These are extremely rare in the U.S., but have had a long history of use in Europe and Russia.
Any time you are dealing with automated plant operations, everything is more finely controlled and the process can make use of unique cements(chemistry, fineness) that may or may not comply with the typical ASTM C150 requirements and larger producers can have specific cements made for the necessary properties based on performance.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
For "normal" concrete used in site cast concrete, the traditional method is to specify the percentage of air required (usually 5-7%, rather the typical 1-2% for un-entrained concrete) to create the small voids in the matrix that allow stresses to be distributed slowly over time and not be disruptive. The old parameters(low absorption and high density) do not always apply for other types of concrete, such as lightweight concrete or lower slump highly compacted concrete products from plants.
Specify a mix design from a supplier or test on site for site cast concrete panels. The admix suppliers conduct routine testing and provide assistance to suppliers to provide uniform results and ofter supply the automated admixture equipment for dispensing. - They make their money from predictable properties and no problems.
For site cast, there is always the old methods of air testing of loads before unloading (I did that too often for a few years) before repeatability was developed. If you insist, there are always the ASTM sampling and testing specification for site cast concrete. The procedure is not reliable for plant produced concrete products.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
Here is the relevant quote from it: [blue]Entrained air for freeze/thaw resistance is not normally required for tilt-up panels since the surfaces are primarily vertical and protected with a paint or sealer. However, if panels are being placed directly against earth or remain untreated, specify air-entrainment in accordance with ACI 318 Chapter Four, Durability Requirements.[/blue]
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