Scientists from the University of Amsterdam managed to find the evidence that the ancient Egyptians used a clever trick to facilitate the transportation of giant stones that were used to build the pyramids.
To create the ancient Egyptian pyramids, builders had to constantly move giant blocks of stone and sculptures through the desert. They had to lift heavy loads and put them on sledges, which were then dragged through the sand.
The experiments of Dutch physicists confirmed that the sand right in front of the sledge was poured with water. When the right proportion of sand was moistened, it could reduce the effort required to transport the cargo by half.
The moisture in the sand increases the formation of capillary bridges, which hold together the separate grains of sand. Thus, the stiffness of wet sand is doubled as compared to dry sand. Due to this, the sand in front of the sledge stops piling up and lets it slide without hindrance, as in the case of dry sand.
It is almost certain that Egyptians knew about this technique. This is evidenced by wall paintings from the tomb of the monarch Djehutihotep, where it is possible to see a person who is wetting sand in front of the sledge.
The study of properties of sand can be of great practical importance in modern technology. Properties of granular materials, which are very common in the world, are still insufficiently studied.
The results of the study, which were published online in the scientific journal Physical Review Letters, could help optimize the transportation and handling of granular materials such as sand, gravel or asphalt.