V Geotechnical properties of clay, principles and application.

2.  GEOTECHNICAL PROPERTIES
 PRINCIPLES
 APPLICATIONS

3.  MECHANICAL STRENGTH : This is normally measured in
terms of resistance to shear, which is a function of the
internal friction and cohesion of the soil
 SOIL MOISTURE CONTENT : When a soil has completed
its free drainage under the action of gravity , it retains
a certain amount of water at a reduced pressure in the
pores and on the surfaces of particles by virtue of the
surface tension and adhesive forces.

4.  MOISTURE MOVEMENT : in the case of saturated flow
in the liquid phase, the permeability or rate of
moisture movement in a soil decreases with increasing
clay content due to increasing proportion of small
capillary channels
 PLASTICITY : This occur when the moisture contents of
the soil as it passes from one state to the next s a wet
slurry of remoulded clay soils dries , it passes through
a series of states, that is liquid ,plastic , semi solid and
solid .

5. Fig 1: Showing the Plasticity range

6.  PLASTICITY
it is defined as a function of
Liquid limit
Plastic limit
Shrinkage limit

7. FIG 2 : GRAPH SHOWING LIQUID LIMIT

8.  This is the water content at which soil ceases
to be entirely plastic and becomes a semi
plastic solid
FIG 2. GRAPH SHOWING PLASTIC LIMIT

9.  This is the water content below which further
loss of moisture does not result in a
decrease in the soil volume
FIG 3 : GRAPH SHOWING SHRINKAGE LIMIT

11.  Refers to cation exchange capacity
 Ability to retained supply nutrient
 Fertility
 HIGH ACTIVITY CLAYS
 Less weathered , high effective surface area
 Smectite , vermiculite , mica ( illite ) , chlorite
 LOW WEATHERED CLAYS
 More weathered , low effective surface area
 kaolinite

14.  GEOLOGICAL SCIENCE
Understanding of geological environments, economic
geology, environmental geology, engineering geology
 CIVIL ENGINEERING
understanding the soil properties, soil behaviour,
foundation and slope stability .
 MATERIAL SCIENCE
understanding the material properties , manufacturing
 SOIL SCIENCE
Soil stability , agriculture