I suggest you add additives to concrete. Sodium chloride is a good choice, which can resist freezing and has early strength effect! Of course, don't use it alone. Another method is to reduce water consumption by adding water reducing agent.

I don't have more innovative's method to maintain it, but it seems like a good suggestion to seal it with polymer on the surface, but the cost is too high to be worthwhile!

Knowledge is not rich enough, so much I can think of, I hope it will help you!