The forces between soil particles maybe of two types:
- Gravitational force and
- Surfaces force
The gravitational force in a soil particle is proportional to its mass i.e, the larger the particle size, the greater would be the gravitational force. So, they are important in case of coarse grained soils only.
Bonding force or surface force between particles depend upon the surface area of the particles and not upon the volume. The surface area also depends upon the particle size. However, the surface force become more important only when the particle size is small. As the particle size decreases, the effect of surface forces on a particle become becomes more prominent than the gravitational force.
A material in which the surface forces are predominant is called as a colloid. In other words, a colloid is a particle with specific surface so high that its behaviour is influenced by the surface energy than the mass energy. For colloids, the ratio o....
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The forces between soil particles maybe of two types:
- Gravitational force and
- Surfaces force
The gravitational force in a soil particle is proportional to its mass i.e, the larger the particle size, the greater would be the gravitational force. So, they are important in case of coarse grained soils only.
Bonding force or surface force between particles depend upon the surface area of the particles and not upon the volume. The surface area also depends upon the particle size. However, the surface force become more important only when the particle size is small. As the particle size decreases, the effect of surface forces on a particle become becomes more prominent than the gravitational force.
A material in which the surface forces are predominant is called as a colloid. In other words, a colloid is a particle with specific surface so high that its behaviour is influenced by the surface energy than the mass energy. For colloids, the ratio of the surface area to the volume is very large. when the particles are very close to the surface, forces can be attractive or repulsive. Vander Waal force, hydrogen bond, cation linkage, dipole-cation-dipole linkage, water-dipole linkage and ionic bond are the possible mechanisms for attractive forces between particles. The repulsive force between particles is mainly due to similar charges on particle surface. The repulsive force between two adjacent particles become effective when they approach each other and their double layer just overlap.
For a given type of clay in suspension, the net force between the adjacent particle at a given separation is the algebraic sum of of the repulsive and attractive forces acting at that distance. The inter-particle force or potential field decreases with increasing distance from the mineral surface.
If the total potential energy between two particles decreases as they approach each other, the particle will experience attraction and will flocculate. On the other hand, if there is an increase in the total potential energy, there will be repulsion and the particle will disperse. The various factors affecting flocculation or dispersion are electrolyte concentration, temperature, ion balance, PH value, dielectric constant and anion adsorption.
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