---
title: "Characteristics of good building stones"
subject: "Civil Engineering Materials"
chapter: 2
key: "semester_3/civil_engineering_materials:characteristics-good-building-stones"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/characteristics-good-building-stones
site: BCT Engineering
---

# Characteristics of good building stones

Civil Engineering Materials · Chapter 2: Building Stones

- Asked in: 2081 Bhadra, 2 marks; 2078 Kartik, 2 marks; 2076 Asoj, 2 marks; 2074 Asoj, 2 marks; 2076 Chaitra, 2 marks; 2074 Chaitra, 2 marks; 2071 Chaitra, 3 marks; 2068 Chaitra; 2068 Baisakh (asked 9 times)
- Video: [Characteristics of Good Building Stones | Properties of Good Building Stone | Civil Engineering](https://www.youtube.com/watch?v=kZ_3yfYEr4M) — Civil Engineering with Tariq
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/characteristics-good-building-stones
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-2

## Question

Write down the characteristics (requirements/selection criteria) of good building stones.

## Short answer

Good building stones must have high crushing strength (≥3.5 N/mm²), low porosity (<5% water absorption), specific gravity ≥2.6, durability against weathering and acids, hardness, toughness, fire resistance, uniform colour, workability, and be free from cracks, cavities, and soft patches. They should be well-seasoned, economical, and locally available.

## Answer

A good building stone should have the following characteristics.

1. **Strength:** high crushing strength (not less than 3.5 N/mm² for ordinary work; granite is 100 N/mm² or more).
2. **Durability:** resists weathering, frost and chemical attack.
3. **Hardness and toughness:** good resistance to abrasion and impact, with a coefficient of hardness above 17 for road work.
4. **Porosity and water absorption:** low, not more than 5% of its weight after 24 hours, otherwise frost and salts damage it.
5. **Specific gravity:** at least 2.6, giving a dense, heavy stone.
6. **Fire resistance:** should not crack or lose strength on heating. Granite is poor; sandstone is good.
7. **Appearance:** uniform colour, fine texture, free from patches, and able to take a good polish.
8. **Workability:** easy to dress and carve without much cost, while still being hard after dressing.
9. **Seasoning:** the quarry sap should have evaporated, so that the stone becomes harder and stronger.
10. **Structure and soundness:** free from cracks, cavities, veins, clay, soft patches, iron pyrites and flaws; a dull sound on striking shows defects.
11. **Cost and availability:** should be economical and available near the site.
12. **Resistance to acids:** should not contain soluble or acid-attacked constituents such as carbonates and sulphates when used in polluted environments.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is the limit on water absorption of a good building stone after 24 hours?
   A. Not more than 5% of weight
   B. Not more than 15% of weight
   C. At least 10% of weight
   D. Not more than 20% of weight
   Answer: A. Low porosity is required, so absorption must not exceed 5% of weight, otherwise frost and salts damage the stone. (Key point: Water absorption)

2. A good building stone should have a specific gravity of at least:
   A. 1.6
   B. 2.6
   C. 1.0
   D. 2.0 or less
   Answer: B. A dense, heavy stone has specific gravity of at least 2.6. (Key point: Specific gravity)

3. How is an unsound stone with hidden cracks or flaws detected by striking?
   A. It gives a clear ringing sound
   B. It gives a metallic ringing sound
   C. It gives a dull sound
   D. It sparks
   Answer: C. A dull sound on striking shows defects, so a sound stone should ring clearly. (Key point: Soundness)

4. What is the minimum crushing strength of stone for ordinary work?
   A. 35 N/mm^2
   B. 100 N/mm^2
   C. 0.35 N/mm^2
   D. 3.5 N/mm^2
   Answer: D. Ordinary work needs not less than 3.5 N/mm^2; only granite reaches 100 N/mm^2 or more. (Key point: Strength)

## Related in Civil Engineering Materials

- [Characteristics of good varnishes](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acharacteristics-good-varnish) — Civil Engineering Materials, chapter 9
- [Characteristics of good bricks](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acharacteristics-good-bricks) — Civil Engineering Materials, chapter 3, asked 4×
- [Characteristics of good timber](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acharacteristics-good-timber) — Civil Engineering Materials, chapter 7, asked 3×
- [Characteristics of good brick earth](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acharacteristics-good-brick-earth) — Civil Engineering Materials, chapter 3
- [Characteristics of a good paint](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acharacteristics-good-paint) — Civil Engineering Materials, chapter 9

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- [Requirements of a good staircase](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Astair-requirements) — Building Technology, chapter 5
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