Cement – #Building Materials

Cement 

1. Introduction

Cement is a fine powder obtained by grinding a mixture of limestone and clay, which when mixed with water forms a paste that sets and hardens, binding other materials together.

👉 In simple words: Cement is a binding material used to make mortar and concrete.

2. Core Concepts
3. Raw Materials of Cement

Main raw materials:

1. Manufacturing Process of Cement

This is a very important exam topic.

Step 1: Crushing and Grinding

• Limestone and clay are crushed
• Ground to fine powder

Step 2: Mixing of Raw Materials

Two methods:

• Wet process
• Dry process (most common)

Step 3: Burning in Rotary Kiln

• Temperature: 1400°C – 1500°C
• Forms hard nodules called clinker

Step 4: Grinding of Clinker

• Clinker is ground with 3–5% gypsum
• Produces Portland cement

1. Composition of Cement

1. Types of Cement

1. Properties of Cement

1. Uses of Cement

• Making concrete
• Masonry mortar
• Plastering
• RCC works

3. Step-by-Step Practical Examples

Example 1: Choosing Cement for Dam Construction

Problem:
Which cement is suitable for a dam?

Step 1: Identify requirement

Dam produces large heat.

Step 2: Match cement type

Low heat cement produces less heat.

➡ Answer: Low Heat Cement

Example 2: Function of Gypsum in Cement

Question:
Why is gypsum added to cement?

Step 1: Observe property

Without gypsum, cement sets too quickly.

Step 2: Identify role

Gypsum controls setting time.

➡ Gypsum prevents flash setting

4. Description of Diagram (Manufacture of Cement)

A flow diagram:

Limestone + Clay → Crushing → Grinding → Mixing → Rotary Kiln (Clinker) → Grinding with Gypsum → Cement

Each step in a rectangular box connected by arrows.

This diagram helps remember manufacturing steps in order.

5. Exam Focus: Must-Know Points ⭐

• Cement is a binding material that sets with water.
• Clinker is formed in a rotary kiln at 1400°C – 1500°C.
• Gypsum controls setting time of cement.
• OPC is used for general construction.
• Low heat cement is used for dams.

6. Multiple Choice Questions (MCQs)
7. Cement mainly acts as a:
8. Aggregate
   B. Binding material
   C. Filler
   D. Reinforcement

Answer: B

Explanation: Cement binds sand and aggregates.

2. Main raw material of cement is:
3. Sand
   B. Limestone
   C. Gypsum
   D. Clay

Answer: B

Explanation: Limestone provides calcium.

3. Which material controls setting time of cement?
4. Clay
   B. Silica
   C. Gypsum
   D. Iron oxide

Answer: C

Explanation: Gypsum prevents quick setting.

4. Temperature in rotary kiln is about:
5. 500°C
   B. 900°C
   C. 1200°C
   D. 1450°C

Answer: D

Explanation: Clinker forms at 1400–1500°C.

5. Clinker is obtained in:
6. Crusher
   B. Grinder
   C. Rotary kiln
   D. Mixer

Answer: C

Explanation: Burning in kiln forms clinker.

6. Cement used for marine works is:
7. OPC
   B. PPC
   C. Rapid hardening
   D. Sulphate resisting

Answer: D

Explanation: Resists sulphate attack.

7. Cement used for road repair works is:
8. OPC
   B. Rapid hardening
   C. Low heat
   D. PPC

Answer: B

Explanation: Gains strength quickly.

8. Which cement is used for mass concrete works?
9. PPC
   B. OPC
   C. Rapid hardening
   D. White cement

Answer: A

Explanation: PPC produces less heat.

9. Fineness of cement mainly affects:
10. Colour
    B. Strength gain
    C. Weight
    D. Soundness

Answer: B

Explanation: Finer cement hydrates faster.

10. Soundness test checks:
11. Strength
    B. Setting time
    C. Volume stability
    D. Colour

Answer: C

Explanation: Prevents expansion after setting.

11. Alumina in cement causes:
12. Slow setting
    B. Quick setting
    C. No effect
    D. Colour change

Answer: B

Explanation: Alumina speeds up setting.

12. Iron oxide gives cement:
13. Strength only
    B. Colour only
    C. Strength and colour
    D. Hardness only

Answer: C

Explanation: Fe₂O₃ improves strength and colour.

13. Low heat cement is used for:
14. Bridges
    B. Dams
    C. Roads
    D. Buildings

Answer: B

Explanation: Reduces thermal cracks.

14. Cement mixed with sand and water is called:
15. Concrete
    B. Mortar
    C. Paste
    D. Grout

Answer: B

Explanation: Mortar = cement + sand + water.

15. Which cement is used for decorative works?
16. White cement
    B. OPC
    C. PPC
    D. SRC

Answer: A

Explanation: White cement is used for finish.

16. Rapid hardening cement is obtained by:
17. Adding lime
    B. Adding gypsum
    C. Finer grinding
    D. Adding sand

Answer: C

Explanation: Finer grinding increases hydration rate.

17. Main function of silica in cement is:
18. Colour
    B. Strength
    C. Setting control
    D. Expansion

Answer: B

Explanation: Silica increases strength.

18. Cement stored for long time becomes:
19. Stronger
    B. Lighter
    C. Lumpy
    D. Coloured

Answer: C

Explanation: Moisture causes lump formation.

19. OPC stands for:
20. Ordinary Portland Cement
    B. Original Portland Cement
    C. Ordinary Pozzolana Cement
    D. Open Portland Cement

Answer: A

Explanation: OPC is general-purpose cement.

20. Which test checks early setting of cement?
21. Soundness test
    B. Setting time test
    C. Fineness test
    D. Strength test

Answer: B

Explanation: Setting time test measures initial and final set.

About the Author

ᑭᑎ ᒪEᗩᖇᑎ ᗩᒪEᖇT

Administrator

Visit Website View All Posts