Problem with radiocarbon dating
The number of dates from the two projects was only large enough to allow for statistical comparisons for the pyramids of Djoser, Khufu, Khafre, and Menkaure. First, there are significant discrepancies between the 19 dates for Khufu and Khafre, but not for Djoser and Menkaure.
Second, the 1995 dates vary widely even for a single monument.
Libby reasoned that since the half-life of C years, the Djoser sample’s C14 concentration should be about 50% of the concentration found in living wood (for further details, see Arnold and Libby, 1949). Subsequent work with radiocarbon testing raised questions about the fluctuation of atmospheric C14 over time.By measuring how much C14 remains in a sample of organic material, we can estimate its age within a range of dates.Samples older than 50,000 to 60,000 years are not useful for radiocarbon testing because by then, the amount of C14 remaining is too small to be dated.Some of this recycled wood was burned, for example, in mortar preparation.