Capillary Rise

Capillary rise is the rise in a liquid above the level of zero pressure due to a net upward force produced by the attraction of the water molecules to a solid surface (e.g., soil or glass).  Tabor, in 1930, recognized that frost heaving required substantially more water than was naturally available in the soil pores (characterized as “moisture content”).  He noted:

“The average soil seldom contains as much as 50 percent water, but if all the water in such a soil were to freeze in situ, the change in volume could cause an uplift of less than 5 percent of the depth of freezing.  The depth of freezing in the colder parts of the United States seldom exceeds 2 or 3 feet; yet a surface heaving of 6 inches is not uncommon and an uplift of a couple of feet has been reported.”

This “extra” water comes from capillary rise. The capillary rise of water can be substantial, up to 6 m (20 ft) or more. The potential capillary rise can be estimated by the following: