PYRAMIDS OF CONCRETE

Dr. Joseph Davidovits, in his book "The Pyramids: an enigma solved" makes a plausible and convincing argument for the Great Pyramid having been built using cement, the blocks being poured, in place. This theory fits the known facts very well, and renders moot the age-old question "how did they cut and move those huge blocks of stone?". I find it easy to imagine long lines of men, each carrying on his shoulder a basket full of cement, gravel or water, walking by the wooden form and emptying his basket, and I find it easy to imagine that there are discoverable methods of making "natural" stone ( mother nature does it! ) The evidence seems to indicate that stonemaking was an Old-Kingdom technology, lost to New-Kingdom builders who used recycled Old-Kingdom stone coupled with mud-brick technology to build lesser works, many of which have already become ruin and rubble. The Romans later 're-discovered' some of this technology after studying Egyptian buildings which were already ancient in Roman times.
Dr. Davidoviits holds patents on methods of making "pyramid" stone. I'm not selling his book, but here's a link that leads to the Davidovits Geopolymer website, if you're interested.