Bricks and Mortar MCQ Quiz - Objective Question with Answer for Bricks and Mortar - Download Free PDF

Explanation:

The Absorption Test is a field test for bricks where a brick is:

• Weighed dry, then

• Immersed in water for 24 hours,

• Removed, wiped dry, and weighed again.

🔸 The percentage increase in weight gives the water absorption capacity of the brick.

As per IS 3495 (Part 2) – 1992:

Water absorption of a brick should not be more than 20% by weight for first-class bricks.

Additional Information

• Hardness Test – Tests resistance to scratching.

• Structure Test – Tests internal flaws by breaking a brick.

• Shrinkage Test – Measures reduction in size upon drying.

Explanation:

• A header bond consists of bricks laid with only their ends (headers) showing on the face of the wall.

• This bond is ideal for curved surfaces because the shorter face of the brick (the header) allows for better alignment and fitting along a curve.

• It provides greater flexibility when following the curvature and ensures a tight, stable construction with minimal gaps.

Additional Information Dutch Bond

• A combination of English and Flemish bonds, often used to strengthen the corners of walls.

• Provides good aesthetics and strength but is less adaptable to curves due to the arrangement of headers and stretchers.

Stretcher Bond

• In this bond, bricks are laid with only the longer face (stretcher) visible.

• Commonly used for partition walls or walls of half-brick thickness.

• Not suitable for curves as long bricks do not align well on curved surfaces.

English Bond

• Alternates courses of headers and stretchers and is known for high strength and structural stability.

• Best suited for straight walls; adjusting header and stretcher courses around curves can be labor-intensive and imprecise.

Explanation:

Types of brick masonry bonds:

Explanation:

Other tools that are used in brick masonry construction:

Brick Hammer: Used for cutting bricks, also for pushing the bricks in courses.

Trowel: Used for lifting and spreading mortar; also for cutting bricks.

Spirit Level: Used, with a straight edge, for getting horizontal surface; also used for leveling.

Plumb rule: Used for checking verticality of brick walls.

Line and Pins: Used for maintaining alignment of courses.

Scutch: Used for cutting soft bricks and dressing out surfaces.

Bolster: Used for accurate cutting of bricks.

Jointer: Used for pointing the joints.

Explanation:

Effect of Excessive Limestone on Brick Colour

Definition: Bricks are one of the most widely used construction materials, and their quality and aesthetic appearance depend significantly on the raw materials used during their manufacturing process. One of the primary constituents that can influence the colour of bricks is limestone (calcium carbonate, CaCO₃). When limestone is present in excess, it reacts during the firing process, causing a distinct change in the brick's colour from red to yellow.

Working Principle: During the firing of bricks, the raw materials undergo various chemical reactions due to the high temperatures in the kiln. Limestone, which is a calcium-based compound, plays an important role in this process. When present in small quantities, limestone contributes positively to the strength and durability of bricks. However, when present in excess, it interferes with the natural chemical reactions of other constituents, such as iron oxide, which is responsible for the red coloration of bricks.

Iron oxide imparts the characteristic red colour to bricks during the firing process. Excessive limestone alters the chemical environment in the kiln by forming compounds such as calcium silicates and calcium aluminates. These compounds suppress the formation of the red iron oxide, resulting in a yellowish colour in the final product.

Chemical Reaction:

The key reactions involved when limestone is present in excess are as follows:

• Decomposition of limestone during heating:

  CaCO₃ → CaO + CO₂ (calcium oxide and carbon dioxide)

• Formation of calcium silicates and aluminates:

  CaO + SiO₂ → CaSiO₃ (calcium silicate)

  CaO + Al₂O₃ → Ca(AlO₂)₂ (calcium aluminate)

These reactions consume the calcium oxide (CaO) generated by the decomposition of limestone. The presence of these newly formed compounds inhibits the normal reactions of iron oxide, leading to the yellowish hue in bricks.

Advantages:

• In controlled amounts, limestone can improve the workability of raw brick material and enhance its durability.
• It contributes to a smoother surface finish in fired bricks.

Disadvantages:

• Excessive limestone significantly alters the natural red colour of bricks, which may be undesirable for aesthetic purposes.
• It can lead to a brittle and weaker brick structure if not carefully controlled during the manufacturing process.

Applications: The use of bricks with a yellowish hue due to excess limestone might be acceptable for specific architectural styles or where the colour variation is not a concern. However, for standard construction practices, controlling the limestone content is crucial to maintain the desired red colour and structural integrity of bricks.

1) Weathering is the process of breaking down and loosening the surface minerals of rock so that they can be transported away by agents of erosion such as water, wind and ice.

2) Quarrying is the multistage process by which rock is extracted from the ground and crushed to produce aggregate, which is then screened into the sizes required for immediate use, or for further processing, such as coating with bitumen to make bituminous macadam or asphalt.

3) Dressing of Stone is the working of quarried stone into the shape and size required for use. This can be necessary as stones obtained from quarrying generally do not have the exact required dimensions or finish.

Concept:

Classification and uses of building stones-

A good building stone has the following properties:

• Percentage of wear in the attrition test should not be more than 3
• Specific gravity should be at least 2.7
• Coefficient of hardness should be greater than 17
• Percentage of water absorption by weight of stone should be less than 5
• Toughness index should not be less than 13
• Crushing strength should be greater than 100 N/mm² or MPa.

A good building stone has the following properties:

• The percentage of wear in the attrition test should not be more than 2 for road work.
• Specific gravity should be at least 2.7
• The coefficient of hardness should be greater than 17
• Percentage of water absorption by weight of stone should be less than 5
• The toughness index should not be less than 13
• Crushing strength should be greater than 100 N/mm²

For road works, Wear not more than 2% and for building stone, It should not more than 3%.

Explanation:

Good Brick Earth Constituents table:

Compacted sandstone: It is a type of rock which has the quartz or the sand bound together with the cementing minerals like mica, feldspar etc.

Compacted sandstone has the following properties:

(a) It is a sedimentary rock

(b) Its colour depends upon that of the feldspar

(c) It can be used as a road metal if the higher quality stones like basalt and granite are not available

(d) It is fire resistant

(e) Its specific gravity is 2.25

(f) Its crushing strength varies 35 to 40 MN/m2

Mangalore tiles are a type of tile native to the city of Mangalore, India. These red coloured clay tiles, unique in shape and size. Since these clay tiles are molded under extreme heat, they are resistant to damage or destruction from fire.

Mosaic tile is any combination of materials such as glass, ceramic, porcelain or stone, usually set in a small format and set on a mesh sheet for easy installation. They are used in backsplash, shower, bath or floor.

Slate tile is a type of natural stone which is quarried from the side of mountains or taken from the earth. A finely grained, homogeneous, metamorphic rock, it is named for the way the material forms in plains, like sheets resting on top of the other, compressed under great pressure to create a strong bond.

Explanation:

Floats are used to press mortar and spread it uniformly.

A trowel is a small hand tool used for digging, applying, smoothing, or moving small amounts of viscous or particulate material.

Aluminium rod is used to strike off excess mortar.

A brush is used to clean the mortar. Floats are used to press mortar and spread it uniformly.

Explanation:

Defects in Bricks are:

1. Bloating: This defect observed as spongy swollen mass over the surface of burned bricks is caused due to presence of excess carbonaceous matter and sulphur in brick clay.

2. Chuffs: The deformation of the shape of bricks caused by the rain water falling on hot bricks is known as chuffs.

Concept:

Kneading: It is the process of mixing water with blended clay (clay with additional minerals) to make it plastic.

Kneading of the brick earth occurs after clay has been weathered, and blended and is the last step in the preparation of brick earth before moulding it into the shape.

Kneading is done either manually or by combined kneading-tempering by adding moisture to the already blended soil and placing it in pug mills (often called as clay mixers).

Kneading is done to obtain a homogeneous mass and to develop plasticity for the following moulding process.

Tempering of clay: It is the process of adding water to the clay and allowing it to remain un-disturbed for few days before mixing occurs.

Pugging: It is also the process of working and tempering of clay to make it plastic and consistent.

Moulding: It is the process of giving a required shape to the brick from the prepared brick earth. It can be hand moulded or machine moulded.