Mention the Necessary Qualities of Brick. Explain the Advantages and Disadvantages of Brick over Stone.
Introduction
Bricks and stones are commonly used building materials. Bricks are manufactured units made from clay, while stones are natural materials obtained from quarries.
Necessary Qualities of Good Brick
Should have uniform size and rectangular shape.
Should be well burnt and have uniform red/copper color.
Should be hard and sound.
Should be free from cracks, holes, stones, and lime nodules.
Should have sharp edges and smooth surfaces.
Water absorption should be low (not more than about 20%).
Should give clear ringing sound when struck together.
Should possess adequate crushing strength.
Should be durable and weather resistant.
Should be free from efflorescence.
Advantages of Brick over Stone
Uniform size and shape.
Easier handling and transportation.
Brick masonry is faster to construct.
Requires less skilled labour.
More economical in many areas.
Better fire resistance.
Easier to make openings and alterations.
Disadvantages of Brick over Stone
Lower strength than stone.
Less durable in severe weather.
Absorbs more water.
Not suitable for very heavy loads.
Cannot provide natural decorative appearance like stone.
Shorter life compared to good quality stone masonry.
Conclusion
Good bricks should be strong, durable, uniform, and properly burnt. Bricks are economical and easy to use, but stone is stronger and more durable.
20. Explain the Constituents of Cement with Their Functions
Introduction
Ordinary Portland Cement contains chemical compounds formed from basic constituents. These ingredients affect setting time, strength, and durability.
Main Constituents of Cement and Their Functions
| S.N. | Constituent | Approx. % | Function |
|---|
| 1 | Lime (CaO) | 60–65% | Provides strength and soundness |
| 2 | Silica (SiO₂) | 17–25% | Gives strength and hardness |
| 3 | Alumina (Al₂O₃) | 3–8% | Helps quick setting and lowers clinkering temperature |
| 4 | Iron Oxide (Fe₂O₃) | 0.5–6% | Gives colour and hardness |
| 5 | Magnesia (MgO) | 1–3% | Small amount gives hardness |
| 6 | Sulphur Trioxide (SO₃) | 1–3% | Helps soundness in limited quantity |
| 7 | Alkalies | Small % | Excess causes efflorescence |
| 8 | Gypsum | 3–5% | Controls setting time |
Conclusion
The proper proportion of cement constituents is necessary to obtain good strength, proper setting time, and durability.
21. Explain the Manufacturing Process of Portland Cement with Net Flow Diagram.
Introduction
Portland cement is manufactured by mixing calcareous and argillaceous materials, burning them to form clinker, and grinding with gypsum.
Manufacturing Process of Portland Cement
There are two methods:
Dry process
Wet process
(Dry process is most common today.)
Steps of Manufacturing
1. Quarrying and Crushing
Limestone and clay are obtained from quarries and crushed into small pieces.
2. Proportioning and Mixing
Raw materials are mixed in proper proportion.
3. Grinding
Materials are ground into fine powder called raw meal.
4. Preheating and Burning
Raw meal is fed into rotary kiln and heated to high temperature (~1450°C) to form clinker.
5. Cooling of Clinker
Hot clinker is cooled in clinker cooler.
6. Addition of Gypsum
About 3–5% gypsum is added to regulate setting time.
7. Final Grinding
Clinker and gypsum are ground into fine cement powder.
8. Storage and Packing
Cement is stored in silos and packed in bags.
Neat Flow Diagram
Limestone + Clay
↓
Quarrying
↓
Crushing
↓
Proportioning
↓
Raw Grinding
↓
Blending
↓
Rotary Kiln
↓
Clinker
↓
Cooling
↓
Add Gypsum
↓
Final Grinding
↓
Storage
↓
Packing
Conclusion
Portland cement is manufactured through quarrying, crushing, grinding, burning in kiln, clinker cooling, gypsum addition, final grinding, and packing. Proper control at each stage ensures quality cement.
