Building Materials: Bricks, Lime, and Tiles - MCQs
1. What is the standard size of a modular brick as per Indian Standards?
Answer: c
Explanation: According to IS 1077, the standard size of a modular brick is 19 cm x 9 cm x 9 cm. With mortar, the nominal size becomes 20 cm x 10 cm x 10 cm, which facilitates modular construction.
2. For a first-class brick, the water absorption after 24 hours of immersion in cold water should not exceed:
Answer: c
Explanation: As per IS 1077, for common burnt clay bricks up to class 12.5, the water absorption should not exceed 20% of its dry weight. For bricks of higher classes, the limit is 15%. Generally, for a brick to be considered first-class, its water absorption should be between 12-15%, but 20% is the maximum permissible limit for it not to be rejected.
3. The minimum compressive strength for a first-class brick should be:
Answer: d
Explanation: A first-class brick should have a minimum compressive strength of 10.5 N/mm² (or 105 kg/cm²). This strength makes it suitable for load-bearing structures.
4. The presence of which substance in brick earth causes bricks to melt and distort during burning?
Answer: b
Explanation: The presence of iron pyrites in brick earth causes the bricks to crystallize and disintegrate during burning. Excess lime and alkalis also act as a flux, causing the bricks to melt, lose shape, and become distorted.
5. The term 'efflorescence' in bricks is caused by the presence of:
Answer: b
Explanation: Efflorescence is the white, powdery deposit that appears on the surface of bricks. It is caused by the presence of soluble salts (like sulphates of sodium, potassium, calcium, and magnesium) in the brick clay, which are brought to the surface by water and left behind when the water evaporates.
6. Flyash bricks are generally considered more environmentally friendly because they use:
Answer: d
Explanation: Flyash bricks are made from fly ash, a byproduct of coal combustion in thermal power plants. Utilizing this industrial waste helps in reducing environmental pollution and conserves natural resources like clay.
7. Which of the following is the main constituent of flyash bricks?
Answer: d
Explanation: The primary constituents of flyash bricks are fly ash, sand or stone dust, and a binder like cement or lime. Gypsum is also added in smaller quantities as an accelerator.
8. The pug mill is used for which process in brick manufacturing?
Answer: a
Explanation: A pug mill is a machine used for tempering the brick earth. Tempering is the process of kneading the clay with water to make it homogeneous and plastic, ready for moulding.
9. Which type of lime is most suitable for works in damp places or under water?
Answer: c
Explanation: Hydraulic lime contains impurities that allow it to set and harden in the presence of water, a process known as hydraulicity. This property makes it ideal for construction in damp environments or underwater.
10. The process of adding water to quicklime to convert it into hydrated lime is known as:
Answer: b
Explanation: Slaking is the exothermic process of adding water to quicklime (calcium oxide) to produce hydrated lime (calcium hydroxide). This process releases a significant amount of heat.
11. Fat lime is also known as:
Answer: b
Explanation: Fat lime is a high-purity lime that is white in color. It is also known as white lime, rich lime, or high-calcium lime. It is primarily used for plastering and whitewashing.
12. Which IS Code classifies common burnt clay building bricks?
Answer: d
Explanation: IS 1077 is the Indian Standard that specifies the requirements for common burnt clay building bricks, including their classification, dimensions, and physical properties.
13. Hydraulic lime is obtained by burning:
Answer: d
Explanation: Hydraulic lime is produced by burning kankar, which is an impure limestone containing a significant amount of clay. The presence of clay imparts hydraulic properties to the lime.
14. Athangudi tiles, famous in Tamil Nadu, are a type of:
Answer: a
Explanation: Athangudi tiles are handmade, decorative tiles that are a type of cement mosaic tile. They are known for their intricate patterns and vibrant colors, created by pouring pigmented cement slurry into moulds.
15. A key characteristic of Athangudi tiles is that they are:
Answer: b
Explanation: Unlike ceramic tiles, Athangudi tiles are not fired in a kiln. They gain their strength through a process of air curing and then being submerged in water for several days. This unique manufacturing process contributes to their distinct character.