Q.: The bottom surface of the overhang on an earth-sheltered house we've built is unattractive in appearance and we must provide some kind of pleasing finish. Either rubbing or machine finishing would be very difficult to do overhead. Sandblasting wouldn't be good because there isn't enough coarse aggregate in the mix.
A.: Probably the best solution is to apply a latex-modified cement paint. There are a number of manufacturers of such products and you should be able to obtain one from your local distributor of concrete specialty materials. Otherwise check the yellow pages of our December Reference Guide, under "Waterproofing and Dampproofing Coatings."