Concrete

According to the newly regenerated Romana II, concrete was created by the addition of gravel to cement. The Fourth Doctor essentially agreed, and called it an indicator of civilisation on the mysterious planet on which they'd landed. (TV: Destiny of the Daleks)
It was invented by the Roman Empire. (COMIC: Quite Interesting)
When Tom Mordley was buried in a golden coffin, it was sealed with concrete. (PROSE: Silver-Tongued Liars)
A car factory in Arcopolis was made of diamond-reinforced type five space concrete. (PROSE: The Eyeless)
Category:Building materials from the real world