Determining Moisture in Aggregate for Mix Proportioning ...
Sand can be expected to contribute about 2 to 6 percent free moisture by weight, and gravel or stone about 1 or 2 percent. Under average conditions that means that 104 pounds of sand would give you the equivalent of 100 pounds of sand in what is called a saturated surface dry (SSD) condition and 4 pounds (1/2 gallon) of free moisture.