Soil at a borrow area has a total unit weight of 120-PCF and a water content of 15 percent. The soil from the borrow area will be used as structural fill and compacted to an average dry unit weight of 110-PCF. The soil shrinkage is most nearly:
Solution:
At the borrow area, the dry unit weight is determined from the equation:
Dry unit weight = Total Unit Weight / (1 + water content)
Dry Unit Weight = 120 / (1 + 0.15) = 104-PCF
The shrinkage factor is the ratio of the volume of compacted material to the volume of borrows material (based on dry unit weight), or:
Shrinkage factor = 104-PCF / 110-PCF = 0.945
Convert the shrinkage factor to a percentage:
Percent shrinkage = (110 - 104) / 110 = 0.055 = 5.5%