A Wellington scientist has come up with an explanation that may help solve the question of how the ancient Egyptians built the pyramids.
It has been widely thought massive blocks of stone cut from quarries were dragged to the building sites.
But Professor Ken MacKenzie from Victoria University had his doubts, so he tested a small sample of a block from the famous Bent Pyramid, built more than 4500 years ago, at his Lower Hutt lab.
He ground it to powder, put in a spectrometer containing a powerful magnet and spun it at a staggering 12,000 revolutions per second.
From that, he was able to get a sub-atomic analysis of the pyramid block. It showed that rather being solid stone, it was a mixture of several materials, a sort of ancient concrete.
"The concrete that would have been used in this instance, if we call it that, this re-constituted stone, would be the earliest form of concrete we know," said MacKenzie.
The mixture, limestone and silica mixed with water and poured into wooden moulds, would have formed symmetrical blocks after setting.
There could be a modern point to all this research into ancient architecture.
Scientists say that if we could replicate those building techniques and materials today, it would be much better for the environment
Making a tonne of modern cement produces almost the same weight in greenhouse gases.