I inspected a house that was built in the mid 1950s, which had a poured concrete foundation that looked great on the inside, with hardly even a typical crack, but had noticeable wear on the outside, especially opposite the driveway side, where there was a gravel surface between the house and the adjacent driveway.
There was hardly any loose or flaking material observed, so this did not appear to be an immediately serious condition, but I am curious about the causes.
Could this be due to the concrete having been poured while it was hardening, the worst areas having been poured last?
Or just a poor mix in general, the effects of accumulating snow, splashing rain, ice melter from the adjacent driveway, etc., having caused the noticeable wear on the outside, while the undisturbed surface inside remained intact?