Test: Bricks and Mortar - Civil Engineering (CE) MCQ

The manufacturing process of bricks involves four distinct operations:

• Preparation of clay can be carried out in the following operations:

Unsoiling: Removal of top 200 mm of soil.
Digging: The remaining soil is dug out and spread over the level field.
Cleaning: Removal of pebbles, stones, and organic and vegetative matter
Weathering:  Clean soil is exposed to the atmosphere for a few weeks to a few months for softening, mellowing, and ripening.

• Blending: To add any ingredient to the clay, it is to be added in this stage by making the clay loose and spread the ingredient over it.
• Tempering: Water is added to the clay in order to bring it up to the required plasticity. It is carried out in Pug Mill.
• Molding: It is a process of giving the required shape and size to the brick either manually or mechanically.
• Drying :It is a process to reduce the moisture content of bricks up to 2 % by drying either naturally or artificially before burning.
• Burning:It is a process of burning bricks in clamps or kilns to impart strength and hardness and make it durable and dense.

• Silica: Silica is a key ingredient in brick earth that helps the brick retain its shape. It provides strength and stability to the brick structure.



• Alumina: Alumina is another important ingredient that contributes to the strength of the brick. It helps in maintaining the shape of the brick during the firing process.



• Magnesia: While magnesia is also present in brick earth, it does not play a significant role in retaining the shape of the brick. It mainly acts as a fluxing agent during the firing process.



• Iron: Iron is another ingredient found in brick earth, but it does not directly contribute to the retention of the brick's shape. It mainly affects the color and texture of the brick.

In conclusion, silica is the primary ingredient in brick earth that enables the brick to retain its shape. Alumina also plays a significant role in providing strength to the brick structure. While magnesia and iron are present in brick earth, they do not have as much influence on the shape retention of the brick. By understanding the properties of these ingredients, brick manufacturers can create high-quality bricks that are durable and long-lasting.

Types of brick masonry bonds:

• Impact on Brick Quality: Excess silica in brick earth can lead to a decrease in the quality of bricks produced.



• Weakening of Bond: Silica is known to reduce the bonding strength between particles in the brick earth, leading to a loss of cohesion.



• Cracking and Breakage: The lack of cohesion due to excess silica can result in bricks that are more prone to cracking and breakage.



• Difficulty in Shaping: Bricks with high silica content may also be more difficult to shape and form properly, affecting their overall structural integrity.



• Reduced Durability: The presence of excessive silica can compromise the durability and longevity of the bricks, making them less resistant to external forces and weathering.

Therefore, it is essential to maintain the right balance of silica in brick earth to ensure the production of high-quality, durable bricks that meet the required standards.

Brick Water absorption:

• It is the difference in weight indicates the amount of water absorbed by the brick in a certain period of time (24 hours) at the standard temperature of the water. It should not exceed 20 percent of the weight of dry brick in the case of first-class brick.

Let the dry weight of the brick is W₁ and the Weight of the brick after 24 hours of immersion in water is W₂.
Water absorbed by brick (w)
= Weight of brick after immersion in water (W₂) - Weight of dry brick (W₁)
Percentage water absorbed by brick (w%)


Where w% = Percentage water absorbed by brick in 24 hours.

• Prevent Shrinkage: Lime is mixed with brick earth to prevent shrinkage during the drying process. Lime helps in reducing the shrinkage of the bricks, making them more stable and less prone to cracking.



• Improve Plasticity: Lime also helps to impart plasticity to the brick earth mixture, making it easier to work with and shape into bricks. This improves the overall workability of the mixture.



• Enhance Durability: Mixing lime with brick earth can increase the durability of the bricks. Lime reacts with the clay minerals in the brick earth, forming a more stable structure that is less susceptible to weathering and erosion.

Overall, mixing lime with brick earth is a common practice in brick making to improve the quality and performance of the bricks produced.

Frog:
A frog in brick is an indentation or depression in one side face, of a molded or pressed brick. If you pick up a brick with a frog, one side will be flat and the other will have a cavity built into it.

Size of frog = 10 cm × 4 cm × 2 cm
Purpose of forg in bricks:

• It facilitates good bonding between two layers of brick as mortar laid in the depressed area forms the good key.
• It reduces the weight of the brick.
• It is used for branding purposes.

• Iron Oxide: Iron oxide is responsible for imparting the red color to bricks. It is commonly used as a pigment in the manufacturing of bricks.


• Silica: Silica is a common component in bricks but does not contribute to the red color. It is primarily used for strength and durability.


• Lime: Lime is used in brick manufacturing to improve workability and reduce shrinkage but does not affect the color of bricks.


• Magnesia: Magnesia is another component in bricks that does not play a role in determining the color of bricks.

Therefore, iron oxide is the key element that imparts the red color to bricks.

Fly-ash:
Fly ash is a fairly divided residue that results from the combination of ground or powdered bituminous coal or sub-bituminous coal like lignite or pulverized coal. It is a by-product of many thermal power stations and other plants using pulverized coal or lignite as a source of heat for boilers. 

Advantages of adding Fly ash as an additive in the brick mix:

• It reduces cost.
• It improves the appearance.
• It increases fire resistance.
• It improves thermal insulating properties.
• It reduces drying shrinkage.
• Reduce crack problems and permeability.
• It also improves strength, etc.

• Definition of Alumina in Brick Earth: Alumina is a compound found in brick earth that plays a crucial role in determining the properties of bricks.



• Plasticity: Alumina enhances the plasticity of the brick earth which makes it easier to shape and mold the bricks during the manufacturing process.



• Improves Workability: The presence of alumina allows the brick earth to be more workable, enabling the bricks to be formed into the desired shapes without cracking or breaking.



• Uniform Composition: Alumina helps in maintaining a uniform composition of the brick earth, leading to consistent quality and strength in the final product.



• Enhances Bonding: The plasticity provided by alumina enables better bonding between the particles of the brick earth, resulting in stronger and more durable bricks.