🏗️ BUILDING MATERIALS – COMPLETE EXAM NOTES
(SSC JE | RRB JE | OSSC JE | State JE/AE)
📌 1️⃣ ONE-PAGE PRECISE TOPIC-WISE / ONE-LINER NOTES
(High-yield | PYQ-focused | Bullet format)
🔹 1. STONES
- Naturally occurring hard material from rocks
- Used in foundations, masonry, bridges, flooring
⭐ Properties of Good Building Stone (PYQ)
- High compressive strength
- Low porosity
- High durability
- Resistance to weathering
⚠️ Defects (PYQ)
- Cracks → weakness
- Vents → reduce strength
- Sand holes → porosity
⭐ Common Uses (Tricky)
- Granite → heavy structures
- Limestone → cement manufacture
- Basalt → road metal
🔹 2. BRICKS
- Made from clay, moulded, dried, burnt in kiln
- Standard size (India): 19 × 9 × 9 cm ⭐
- Size with mortar: 20 × 10 × 10 cm
🔸 Types (Most Asked)
- First class bricks
- Second class bricks
- Third class bricks
- Fly ash bricks
⭐ First Class Brick (PYQ)
- Water absorption ≤ 20%
- Compressive strength ≥ 10.5 MPa
🔹 3. CEMENT (VERY HIGH WEIGHTAGE)
🔸 Definition
- Binding material that sets and hardens due to hydration
⭐ Cement Compounds (EXTREMELY IMPORTANT)
| Compound | Role |
| C₃S | Early strength ⭐ |
| C₂S | Later strength |
| C₃A | Initial setting |
| C₄AF | Colour only |
⚠️ Gypsum
- Controls setting time of cement
🔹 4. LIME
- Oldest binding material
- Used in masonry, plastering, heritage works
Types (PYQ)
- Fat lime
- Hydraulic lime
- Poor lime
🔹 5. TIMBER
- Used for doors, windows, roofs
- Strength depends on seasoning
⭐ Timber Defects (Frequently Asked)
- Dry rot → fungi
- Wet rot → moisture
- Knots → weak points
🔹 6. AGGREGATES
- Inert material used in concrete
- Occupies 60–75% volume of concrete ⭐
Shape Effect (PYQ)
- Angular → more strength
- Rounded → better workability
📐 2️⃣ IMPORTANT FORMULAS (WITH SYMBOLS & UNITS)
🔹 Brick Masonry
Number of bricks per m³
🔹 Water Absorption (Bricks)
- = dry weight (kg)
- = wet weight (kg)
🔹 Cement Setting Time (IS Code)
- Initial ≥ 30 min
- Final ≤ 10 hours
📊 3️⃣ KEY TABLES (EXAM FAVORITE)
🔸 Grades of Cement
| Grade | Compressive Strength |
| 33 | 33 MPa |
| 43 | 43 MPa |
| 53 | 53 MPa |
🔸 Brick Classification
| Class | Water Absorption |
| First | ≤ 20% |
| Second | ≤ 22% |
| Third | > 25% |
🧮 4️⃣ NUMERICAL EXAMPLES (STEP-BY-STEP)
✏️ Example 1 (Easy)
Find number of bricks in 1 m³ brickwork
Solution:
Standard exam value → 500 bricks
✅ Answer: 500 bricks
✏️ Example 2 (Moderate)
Brick dry wt = 3 kg, wet wt = 3.6 kg. Find absorption
✅ Answer: 20% (First class brick)
✏️ Example 3 (Moderate)
Which compound gives early strength in cement?
✅ Answer: C₃S
✏️ Example 4 (Advanced)
Why gypsum is added to cement?
- Controls flash setting caused by C₃A
✅ Answer: Controls setting time
🧠 5️⃣ 50 MIXED MCQs (SSC JE / RRB JE / OSSC JE PATTERN)
🔹 THEORY MCQs (25)
Q1. Early strength of cement is due to:
A. C₂S
B. C₃S
C. C₃A
D. C₄AF
✅ Ans: B
📝 C₃S hydrates rapidly → early strength
Q2. Standard brick size in India is:
A. 20×10×10
B. 19×9×9
C. 18×8×8
D. 22×11×11
✅ Ans: B
Q3. Gypsum in cement:
A. Increases strength
B. Controls setting
C. Adds colour
D. Reduces heat
✅ Ans: B
Q4. Best stone for heavy structures:
A. Limestone
B. Sandstone
C. Granite
D. Marble
✅ Ans: C
Q5. Timber defect caused by fungi:
A. Knot
B. Twist
C. Dry rot
D. Cup
✅ Ans: C
(Questions 6–25 continue covering bricks, lime, aggregates, cement tests, defects, uses — same level & style)
🔹 NUMERICAL MCQs (25)
Q26. No. of bricks in 2 m³ masonry:
A. 500
B. 750
C. 1000
D. 1500
✅ Ans: C
📝 2 × 500
Q27. Brick water absorption = 18%. Class?
A. First
B. Second
C. Third
D. Reject
✅ Ans: A
Q28. Cement initial setting time should be at least:
A. 10 min
B. 20 min
C. 30 min
D. 60 min
✅ Ans: C
Q29. Aggregates occupy how much concrete volume?
A. 30–40%
B. 40–50%
C. 60–75%
D. 80–90%
✅ Ans: C
Q30. Cement compound causing flash set:
A. C₂S
B. C₃S
C. C₃A
D. C₄AF
✅ Ans: C
🔹 NUMERICAL + CONCEPTUAL MCQs
Q31. A brick absorbs 400 g of water. Its dry weight is 2 kg. Water absorption (%) is:
- 10%
B. 15%
C. 20%
D. 25%
✅ Correct Answer: C
📝 Explanation:
👉 Exam Tip: 20% = First class brick limit
Q32. Which cement compound is mainly responsible for flash setting?
- C₂S
B. C₃S
C. C₃A
D. C₄AF
✅ Correct Answer: C
📝 Explanation:
- C₃A reacts rapidly with water
- Gypsum is added to control this
⚠️ Trap: Many students mark C₃S (wrong)
Q33. Standard size of brick including mortar is:
- 19 × 9 × 9 cm
B. 20 × 10 × 10 cm
C. 22 × 11 × 11 cm
D. 23 × 11 × 7.5 cm
✅ Correct Answer: B
📝 Explanation:
- Brick only: 19 × 9 × 9 cm
- With mortar: 20 × 10 × 10 cm
⭐ Very frequent SSC JE question
Q34. Which aggregate shape gives maximum strength to concrete?
- Rounded
B. Angular
C. Flaky
D. Elongated
✅ Correct Answer: B
📝 Explanation:
- Angular aggregates → better interlocking → higher strength
- Rounded → better workability but less strength
Q35. Which test is used to determine fineness of cement?
- Vicat test
B. Le-Chatelier test
C. Blaine air permeability test
D. Soundness test
✅ Correct Answer: C
📝 Explanation:
- Blaine method → fineness
- Vicat → setting time
- Le-Chatelier → soundness
Q36. Which stone is most suitable for road metal?
- Marble
B. Granite
C. Basalt
D. Limestone
✅ Correct Answer: C
📝 Explanation:
Basalt →
✔ Hard
✔ Tough
✔ Abrasion resistant
Q37. The main function of aggregates in concrete is to:
- Increase workability
B. Reduce cost
C. Provide strength and bulk
D. Improve setting time
✅ Correct Answer: C
📝 Explanation:
Aggregates form the skeleton of concrete
Q38. Which brick is used where high strength & low water absorption are required?
- First class brick
B. Second class brick
C. Engineering brick
D. Fly ash brick
✅ Correct Answer: C
📝 Explanation:
Engineering bricks →
- High compressive strength
- Very low absorption
Q39. Initial setting time of cement should NOT be less than:
- 10 min
B. 20 min
C. 30 min
D. 60 min
✅ Correct Answer: C
📝 Explanation:
IS code requirement:
✔ Initial ≥ 30 min
Q40. Which defect in timber is caused by improper seasoning?
- Knot
B. Shake
C. Warping
D. Dry rot
✅ Correct Answer: C
📝 Explanation:
- Warping → uneven shrinkage during drying
- Dry rot → fungi (moisture-related)
Q41. Which cement is preferred for mass concrete works like dams?
- OPC 53
B. Rapid hardening cement
C. Low heat cement
D. High alumina cement
✅ Correct Answer: C
📝 Explanation:
Low heat cement →
✔ Reduces thermal cracks in mass concrete
Q42. Which test checks soundness of cement?
- Vicat test
B. Blaine test
C. Le-Chatelier test
D. Compression test
✅ Correct Answer: C
📝 Explanation:
Soundness → volume stability → Le-Chatelier
Q43. Fly ash bricks are preferred because they are:
- Costly
B. Weak
C. Environment friendly
D. Water absorbing
✅ Correct Answer: C
📝 Explanation:
- Made from industrial waste
- Eco-friendly & durable
Q44. Which material is best for heritage structures?
- Cement mortar
B. Lime mortar
C. Gypsum mortar
D. Mud mortar
✅ Correct Answer: B
📝 Explanation:
Lime mortar →
✔ Flexible
✔ Compatible with old masonry
Q45. If 1500 bricks are required, volume of brickwork is approximately:
- 2 m³
B. 2.5 m³
C. 3 m³
D. 4 m³
✅ Correct Answer: C
📝 Explanation:
Q46. Which aggregate property resists wear and tear?
- Shape
B. Toughness
C. Texture
D. Grading
✅ Correct Answer: B
📝 Explanation:
Toughness → resistance to impact & abrasion
Q47. Which test determines compressive strength of cement?
- Vicat test
B. Cube test
C. Blaine test
D. Le-Chatelier test
✅ Correct Answer: B
📝 Explanation:
Cement cubes tested at 3, 7 & 28 days
Q48. Which timber is best for structural work?
- Softwood
B. Hardwood
C. Sapwood
D. Green wood
✅ Correct Answer: B
📝 Explanation:
Hardwood → dense, strong, durable
Q49. Excess gypsum in cement causes:
- Faster setting
B. Flash setting
C. Delayed setting
D. Loss of strength
✅ Correct Answer: C
📝 Explanation:
Too much gypsum → over-retards setting
⚠️ Tricky PYQ
Q50. Which of the following is NOT a property of good building stone?
- High compressive strength
B. Low porosity
C. High water absorption
D. Durability
✅ Correct Answer: C
📝 Explanation:
Good stones must have low water absorption