In this experiment, three different conditions regarding the wetness of sand were studied — dry sand, wet sand, and sand saturated with water.

Dry sand Angle of repose — 33°

Water was added to dry sand to make it wet, and then more water was added until it became saturated

	Wet sand
Water increases the cohesion of sand particles and between the sand and the surface of the container. The sand did not fall when the slope approached 90°. The binding effect of water can even allow the sand to form an arch.

	Sand saturated with water
More water was added to the container to saturate the sand		Angle of repose — 29°

Conclusion: When sand is wet, water acts as a binding factor between the particles, but when it is saturated, water acts as a lubricant. The angle of saturated sand is lower than that of dry sand, while the angle of wet sand is much higher, even reaching over 90°.