An example of a re-agglomerated limestone
How the pyramid blocks were built ?
Does the picture show an artificial or a natural stone? Scientists of the Geopolymer Institute have successfully manufactured and cast a re-agglomerated limestone. The geological material used here is very similar to the one found at the Giza plateau in Egypt, a soft material with lots of nummulitic shells coming from a quarry in France. The purpose of this test was to demonstrate that this type of limestone is perfect for re-agglomeration. We have disaggregated this soft material with water, then mixed the muddy limestone and its fossil shells with kaolin clay, and a simple geopolymeric binder. Then, the limestone mud was packed into the mould (a pyramid shape!). This re-agglomerated limestone, bonded by a geochemical reaction, thus hardened into a resistant block, much harder than the original material. We have strengthened the stone and made it more resistant to pollution, acid rain, and freezing.
A close-up of the mini-pyramid. Fossil shells are intact and the geopolymer binder is integrated within the calcite matrix.
The mini-pyramid is 9 cm (3.55 inch) large. In these pictures, you can clearly see that anyone who is not aware of the possibility of the geopolymer chemistry can be easily fooled. The final result has not a modern concrete appearance. It is a natural limestone, the material was not crushed but gently disaggregated, and all fossil shells are intact.
A close-up of the bottom of the mini-pyramid. The bottom was the top of the mould, the mini-pyramid was cast upside-down.
Because we were not authorized to sample original materials from the Giza plateau quarries, we did not used the exact ancient Egyptian formula. The French limestone, used in this experience, is very similar but has no reactive clay in it, and we had to add some. Nevertheless, the final result is chemically and geologically close to what we find in Egypt.
With the Egyptian formula, the result is different because it requires bigger blocks for a better cohesion. It is not suitable for small items. Whatever the formula, we have clearly demonstrated that the key of success is an appropriate raw material.
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