Is pavement a countable or incountable noun? Thank you
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. both pavements are quite expensive, however." (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. in this case, you might be able to use it in a "countable" sense, but this is likely a regionalism, if indeed it exists.
A good trick to remember is:

Does the sentence: "We have 5 pavements." make sense?

If it makes sense, then pavement is countable. If not, then pavement is uncountable.