from this article by wired.com’s danger room:
After just a few hours a Pyrament runway is ready for the heaviest aircraft, reaching a strength that conventional concrete can only match after several days.
Pyrament is one type of a new technology called geopolymers. they harden faster than traditional concretes and to higher strengths. very cool technology.
as an interesting aside, it’s been suggested by one of the main creators of geopolymers that they were used to build the pyramids. even more interesting is that, according to the article:
recent X-ray and microscopic study of samples has supported the theory that the pyramids are made of artificial stone.