This little Guardian/Observer article introduces the ideas of Joël Bertho, an architect and specialist in reconstituted stone. And they have a lot of validity. If it was possible to take a mixture up the pyramids in buckets, and then create the blocks there, then we can forget all about ramps, pulleys, ropes and so on. And it is more believable than sonic levitation.

Apparantly the authorities won't let this chap gather any more samples for comparison.

Others have previously theorised on this. There is an excellent four-part article online at Geopolymer.org, as well as a whole book on the subject.