"There are ramshackle _cement_ rectangles squatting under rain clouds..."
It's concrete [1] not cement. Even the word cementing can mean "settle or establish firmly", which is what happens to the aggregate in concrete. Augh.
[1]: http://www.todayifoundout.com/index.php/2011/12/the-differen...
One of the widely accepted, dictionary definitions of "cement" is simply "concrete." (In fact, Merriam Webster has this listed as definition #1.) I understand that the terms have different technical meanings, but in common English they are simply synonyms.
E.g., http://www.merriam-webster.com/dictionary/cement
There may be an opportunity for a Battle of the Dictionaries here, but I think this skirmish in the language wars may be over.
edit: Ah! Also cool is dental cement [2] which is, as the name would imply, used in dentistry (but without any aggregate equivalent!).