No to sealer. The only way concrete will get damaged is if there's vehicular traffic allowed, and there are no expansion joints (control joints to be technically correct) of any kind. 

Now, what the hell is a concrete flag?

This?

Thanks, Rusty. I figured you would have had some experience with this. Hearing various contractors tell me the way they do things had me second guessing myself.

And yes, that flag is exactly what we had done. But we had a flag done for every country represented in the coop. We are truly multi-cultural! ;-)

Yay to multi-culturism! 

Two of my current clients are landscape architects, so exterior concrete work is something I deal with on weekly basis. The only reason you would ever use a concrete sealer is in order to protect any finishes installed on top of concrete, or in order to protect assemblies below. Not applicable for most exterior work.

Everything falls apart eventually. So your kids will eventually have to deal with this. Hopefully 50 years from now.

btw, congrats on getting the perfect match on concrete aggregate. It's harder than it seems.

there's also this stuff:

http://www.xypex.com/

it's not a sealant in the sense of putting a layer on -- it chemically produces crystals that "grow" through the pores and micro-fractures in the concrete, creating a sort of sealant crystal network that can penetrate up to a foot deep from the face of the concrete.  we got a presentation on it a while back, really impressed us -- at least some of that info should be in the videos on this page:

http://www.xypex.com/aboutus/media.php

can be put in the concrete mix or added later...

Derek, xypex makes standard crystalline concrete products. Nothing magical about that. 

As a spec writer, the standard question I pose to designer in charge is 'what are you trying to protect here'? Concrete breaths and cures very slowly, but is fine when left alone. If anything, you want to seal concrete in order to protect the surrounding materials. For instance, terrazzo flooring has a well documented history of failure. The culprit? Still curing concrete undelayment.  

say what you want, but that carriage they came in on was a pumpkin til they put xypex on it...

Well, if you buy a pumpkin covered in xypex, please don't eat it. Crystalline products are also used in order to kill fleas and ant colonies. They will make your stomach explode. 

Banned in Canada for insect control purposes.

I remember having attended a few Xypex lunch-and-learns. I think it's more intended for waterproofing of vertical surfaces. I think it's also cement-based, so not appropriate for decorative surfaces like exposed agg. Your post did get me thinking however. There is Chem-crete Yufix which does seem more appropriate for waterproofing decorative surfaces and is less caustic than Xypex. (Again however, I don't believe intended for horizontal surfaces.)

http://www.chem-crete.com/products/details.aspx?CategoryID=2&ProductID=6

In any case, Rusty's confirmed my gut instinct that a sealer really isn't necessary on public walks.

In regards to matching the existing agg, we have an in-house site studio where I could look at a variety of aggregates. I was torn between using a 5/8" pea gravel and an MDOT 6A. Went to a site meeting with the contractor, and he confirmed I needed the size variation of the 6A and helped me with the color match. In general, I had a good experience with this contractor. Will go back to him for future work.

Thanks all for the insight.

The only reason you would want to seal a concrete walk is to prevent damage from freeze/thaw cycling.  Many bridges and parking structures are sealed just for that reason and to protect water from reaching the reinforcing, if not provided with an epoxy coating.  Products commonly usedare formulations with a penetrating sealant consisting of silane or siloxane.

If exposed aggregate is costly and has time-consuming repairs, why go for it in the first place? Choose something which can match your choice. It falls short on the functional benefits to some extent, although not entirely. How about using an asphalt rather than concrete or exposed aggregate? http://www.lincolngroup.ca/