Few years ago I read article in popular slovak scientific magazine about one of these theories. The article was very interesting and what's important based on rational evidence rather than fabulous stories. The main point of this theory was that pyramid blocks were casted instead of carved. In another words the pyramid blocks are artificial stones casted directly on construction place. This would be more practical if you take in mind that nearest stone-pit is few tenths of kilometers from Great pyramids in Giza. It is simpler to transport loose material than solid material. The estimated number of people doing on great pyramids were only 1500 which is quite reasonable.
The fact that some of pyramid blocks were prepared on the building place can be discerned under the microscope. There are some people doing research in this area. One of them is Joseph Davidovits. He shows how the Pyramids were built by using re-agglomerated stone (a natural limestone treated like a concrete), and not with huge carved blocks, hauled on fragile ramps.
A new scientific analysis demonstrates the artificial nature of Egyptian Pyramid stone. The article titled: “Were the casing stones of Senefru’s Bent Pyramid in Dahshour cast or carved? Multinuclear NMR evidence” was published in Materials Letters 65 (2011) 350–352, by an international team of scientists involving Kenneth J.D. MacKenzie (MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, New Zealand), Mark E. Smith, Alan Wong, John V. Hanna (Department of Physics, University of Warwick, Coventry, CV4 7Al, UK), Bernard Barry (Institute of Geological and Nuclear Sciences, Lower Hutt, New Zealand) and Michel W. Barsoum (Department of Materials Science and Engineering, Drexel University, Philadelphia, PA 19104, USA).
The abstract reads: “A comparison was made of the solid-state 29Si, 27Al and 43Ca MAS NMR spectra of the outer casing stone from Snefru’s Bent Pyramid in Dahshour, Egypt, with two quarry limestones from the area. The NMR results suggest that the casing stones consist of limestone grains from the Tura quarry, cemented with an amorphous calcium-silicate gel formed by human intervention, by the addition of extra silica, possibly diatomaceous earth, from the Fayium area.
More information can be found on this site: http://www.geopolymer.org/category/archaeology/pyramids