i would say "incountable", never to be used in the plural. that being said however, in a technical sense, one may be speaking of different types of road surfaces, and therefore one might say something like: "asphalt and cement both give a smooth surface to a roadway. " (here, "pavement(s)" speaks of the paving METHOD) i also think that i have heard or read the word "pavement" used as a word for parking lot.
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