Brick Earth and its Ingredients

Brick earth is a type of soil that is commonly used for making bricks. It is composed of various ingredients that contribute to the properties of the soil. The main ingredients of brick earth are:

- Alumina
- Silica
- Lime
- Magnesia
- Iron oxide
- Potash and soda

Out of these ingredients, silica plays a crucial role in retaining the shape of the brick.

Role of Silica in Retaining Brick Shape

Silica is a hard and durable mineral that is found in abundance in brick earth. When the brick is fired in a kiln, the silica in the clay starts to melt and fuse together. This process is called vitrification, and it creates a glassy matrix that binds the other ingredients together.

The glassy matrix formed by the silica provides strength and rigidity to the brick structure. It helps the brick to retain its shape even under heavy loads and adverse weather conditions. The higher the percentage of silica in the brick earth, the stronger and more durable the brick will be.

Other Ingredients and their Roles

While silica is the most important ingredient for retaining the shape of the brick, the other ingredients also play crucial roles in the properties of the brick. Some of these roles include:

- Alumina: Provides plasticity and workability to the clay mixture.
- Lime: Helps to reduce shrinkage and cracking during firing.
- Magnesia: Provides strength and durability to the brick structure.
- Iron oxide: Gives the brick its characteristic color and helps to reduce water absorption.
- Potash and soda: Help to reduce the melting point of the clay and improve the bonding between the ingredients.

Conclusion

In conclusion, the correct answer to the question is option D, silica. Silica plays a crucial role in retaining the shape of the brick by creating a glassy matrix that binds the other ingredients together. While the other ingredients also contribute to the properties of the brick, silica is the most important for its strength and durability.