Capillarity

Capillarity :

                  it is the ability of the soil to transmit moisture in all directions regardless of any gravitational force. Soil possess capillary action similar to a dry cloth with one end immersed in water. Water rises up through soil pores due to capillary attraction. the maximum theoretical height of capillary rise depends upon the pressure which tends to force the water into the soil, and this force increases as the size of the soil particles decreases. the capillary rise in a soil when wet may equal as much as 4 to 5 times the height of capillary rise in the same soil when dry.

1. Coarse gravel has no capillary rise; 
2. coarse sand up to 30 cm; 
3. fine sand and silts have capillary rise up to 1.2 m but dry sands have very little capillarity.
4. clay may have capillary rise up to 0.9 to 1.2 m but pure clay have low value.
5. in coarse-grained soils, the time required to reach the limit of the rise is much less than in fine-textured soils.