id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
en-wikipedia-org-9380		Roman concrete - Wikipedia			.html	text/html	2656	448	52	Roman concrete, also called opus caementicium, was a material used in construction in Ancient Rome. The city of Caesarea was the earliest known example to have made use of underwater Roman concrete technology on such a large scale.[5] Compressive strengths for modern Portland cements are typically at the 50 megapascals (7,300 psi) level and have improved almost ten-fold since 1860.[11][12] There are no comparable mechanical data for ancient mortars, although some information about tensile strength may be inferred from the cracking of Roman concrete domes. Hobbs, "Roman Concrete and the Roman Architectural Revolution", Ceramics and Civilization Volume 3: High Technology Ceramics: Past, Present, Future, edited by W. ^ Heather Lechtman and Linn Hobbs "Roman Concrete and the Roman Architectural Revolution", Ceramics and Civilization Volume 3: High Technology Ceramics: Past, Present, Future, edited by W.D. Kingery and published by the American Ceramics Society, 1986; and Vitruvius, Book II:v,1; Book V:xii2	./cache/en-wikipedia-org-9380.html	./txt/en-wikipedia-org-9380.txt