Cohesion is the component of shear strength of a rock or soil that is independent of interparticle friction.

In soils, true cohesion is caused by one of three things:

1. Electrostatic forces in stiff overconsolidated clays (which may be lost through weathering)
2. Cementing by Fe₂O₃, CaCO₃, NaCl, etc
3. Root cohesion (which may be lost through logging or fire of the contributing plants, or through solution)

There can also be apparent cohesion. This is caused by:

1. Negative capillary pressure (which is lost upon wetting)
2. Pore pressure response during undrained loading (which is lost through time)

See also

• Angle of repose

References

• Collins internet-linked dictionary of Geology

Topics in geotechnical engineering
Soils
Soil properties
Soil mechanics
Geotechnical investigation
Laboratory tests
Field tests
Foundations
Retaining walls
Slope stability
Earthquakes
Geosynthetics
Instrumentation for Stability Monitoring