Joseph Davidovits and Margaret Morris started this debate. The geopolymer website is pretty unclear. I am "pretty familiar" with their theory... and will attempt to restart this debate. First, there are many errors in their arguments. Second, they are poorly presented. Third, I am not endorsing or promoting whether the pyramids were made of concrete or not, but I wish to re-introduce their argument.
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Statement 1: Many pyramid blocks were carved. A quary of Carved Blocks exists.
Response 1: Davidovits and Morris claim that these were from "repair work" on the pyramids. This answer is kind of a hybrid theory... some were cut, and some were poured.

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Statement 2: What is a geopolymer??
Response 2: geopolymer is a funny word for "roman concrete". Roman Concrete is known for using volcanic ash, or Pozzalon. Since volcanic ash isn't prevalent in egypt, an alternate "Pozzalon" must be substituted. Davidovits chooses: A. Kaolin Clay, and B. Plant Ash. A. Kaolin Clay is found nearby the pyramids. B. Plant Ash should be around from the creation of "Gypsum".

There is evidence that Romans created some concrete with "Crushed Clay Tiles". There is also some evidence of the Greeks creating concrete in 900BC, using Volcanic Ash, in Rhodes.

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Statement 3: Davidovits claims "the wheel" was not yet invented in Egypt.
Response 3: His theory is predicated on the invention of Pottery, and hence the "Pottery WHEEL".

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Statement 4: Davidovits claims the stones could not be cut with the ancient copper saws of the day.
Response 4: The obelisk of Sesotris 1 - ~1900BC, seems to indicate the Egyptians could cut large stones at a very early date.