Ancient Egyptians may have used moistened sand to help move pyramid stone by sledge.
This technique could have allowed the builders to require only half of the manpower to move the giant rocks, Phys.org reported.
Large pyramid stones that needed to be transported across the desert were placed on a sledge and pulled by workers; this new research suggests the Egyptians wet the sand in front of the sledge before pulling it.
The researchers showed the right amount of water could make a sledge need only half the force to be pulled. They proved this by determining the stiffness of the sand when it contained different quantities of water. They used a rheometer to determine how much force was required to deform sand at different levels of wetness.
"Experiments revealed that the required pulling force decreased proportional to the stiffness of the sand," Phys.org reported.
The addition of water created capillary bridges in the sand that, which bound the sand grains together. The team found this caused the sand to be twice as stiff as it would have been if dry. Stiffer sand would allow the sledge to move across its surface with much more ease because its movement does not cause sand to pile up in front.
An ancient wall painting found in the tomb of Djehutihotep depicts a person standing on the front of a moving sledge and pouring water over the sand in front of it, Phys.org reported.
Today's scientists do not fully understand granular material like sand; this finding could prompt researchers to gain more insight into the materials.
Examples of granular material are "asphalt, concrete and coal," Phys.org reported. The new research could help researchers gain insight into how to improve transportation of granular material, which makes up 10 percent of the world's energy consumption.
