Clay is one of the widely used types of earth mainly because of its unique physical characteristics. Clay has the property to be deformed into different shapes as a result of exerted force or plasticity when wet, but when heated it hardens and turns into a rock solid breakable material. The main cause of clay’s plasticity is the variable amount of water trapped inside the mineral structure through polar attraction. There are also some organic materials that are part of clay deposits though they don’t possess plasticity.

 

Basically, clay is made up of fine-grained clay minerals, primarily of aluminum silicate. Clay minerals are also a subtype of phyllosilicate minerals. These minerals are responsible for the plasticity of clay. Clays are formed by gradual weathering of different variations of rocks such as felspathic and igneous rocks, traces of hydrated aluminum silicates and low concentrations of carbonic acid and other solvents over longer periods of time. These acidic solvents merge with the weathering rocks to form clay.

 

Clay is made up of the following minerals:

 

  • Clay minerals (60%)
  • Quartz (30%)
  • Feldspar (5%)
  • Carbonic Acid (4%)
  • Iron oxides and organic matter (2%)

 

Here are some of the common properties of clay.

 

  • Clay typically dries at 100 degrees Celsius as it loses its trapped water.
  • Clays can be molded to different forms and shapes when applied by force. Clays have high plasticity especially when they are wet. When dried, clays become firm and stiff when dried at 100 degrees Celsius.
  • Clay’s plastic property might increase over the years by storing it in a humid place or by exposing it to the weather. The reason for this increased plasticity is due to the combination of hydration and gelation processes.

 

Uses of Clay

 

Clays has been providing major contributions throughout history. During the ancient times, clay was used as the first medium for writing (cuneiform). Other uses of clay are in making ceramics, bricks, pots, artworks and musical instruments. In infrastructure, clay is commonly used as an ingredient in cement production and in chemical filtering. Since clay is almost impenetrable by water, it is also used in creating landfill barriers and cores for drums.

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