---
title: "Classification of bricks"
subject: "Civil Engineering Materials"
chapter: 3
key: "semester_3/civil_engineering_materials:classification-of-bricks"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/classification-of-bricks
site: BCT Engineering
---

# Classification of bricks

Civil Engineering Materials · Chapter 3: Clay Products

- Asked in: 2078 Bhadra, 1 marks; 2066 Shrawan (old course), 5 marks; 2081 Baisakh (new course), 1 marks (asked 3 times)
- Video: [Classification of Bricks & Properties of Good Bricks | Building Materials](https://www.youtube.com/watch?v=B1DWMX3Tibk) — SGK Online Education
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/classification-of-bricks
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-3

## Question

How do you classify bricks? Explain the classes of bricks (1st class, 2nd class) and their engineering application.

## Short answer

First-class bricks are well burnt, uniform, with sharp edges, water absorption ≤20%, strength ≥10.5 N/mm², used for load-bearing walls and exposed work. Second-class bricks are slightly irregular, water absorption up to 22%, strength ~7 N/mm², used for plastered walls and general interior work.

## Answer

Bricks are classified in several ways.

#### 1. By manufacture
- **Unburnt (sun-dried)** and **burnt** bricks.

#### 2. By quality (burning)
- **First class:** well burnt, uniform red colour, regular shape, sharp edges, ringing sound, water absorption not more than 20%, compressive strength not less than about 10.5 N/mm². Used for superior work: load-bearing walls, brick flooring, face work and exposed structures.
- **Second class:** slightly irregular shape and rough surface, less uniform colour, water absorption up to 22%, strength about 7 N/mm². Used for walls that are to be plastered, for general and interior work and for non-load-bearing partitions.
- **Third class:** under-burnt and soft, absorbing up to 25% water, strength about 3.5 N/mm²; used for temporary work and in dry places.
- **Fourth class (jhama, over-burnt):** used as aggregate in lime concrete, as road metal and in foundations.

#### 3. By use
- Common bricks, facing bricks, engineering bricks, fire bricks, and perforated and hollow bricks.

#### 4. By strength (IS 1077)
- Classes 35, 30, 25 ... down to 3.5, according to the minimum compressive strength in N/mm².

## Check yourself

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

1. First class bricks absorb water up to:
   A. 22%
   B. 20%
   C. 25%
   D. 5%
   Answer: B. First class: 20%; second: 22%; third: 25%. (Key point: First class absorption)

2. Second class bricks are used for:
   A. Face work in exposed structures
   B. Fire bricks
   C. Plastered walls and general or non-load-bearing work
   D. Foundations only
   Answer: C. They are slightly irregular so are plastered. (Key point: Second class use)

3. Over-burnt (jhama) bricks are used as:
   A. Face bricks
   B. Roof tiles
   C. Load-bearing walls
   D. Aggregate in lime concrete and road metal
   Answer: D. They are over-burnt and used as aggregate. (Key point: Fourth class)

4. Third class bricks are:
   A. Under-burnt and soft, for temporary work
   B. Over-burnt
   C. Glazed
   D. Used for load-bearing walls
   Answer: A. They absorb up to 25% water. (Key point: Third class)

## Related in Civil Engineering Materials

- [Classification of civil engineering materials](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aclassification-civil-materials) — Civil Engineering Materials, chapter 1, asked 2×
- [Field tests of bricks](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Afield-tests-of-bricks) — Civil Engineering Materials, chapter 3, asked 5×
- [Manufacturing process of bricks](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Amanufacturing-process-of-bricks) — Civil Engineering Materials, chapter 3, asked 4×
- [Why bricks are widely used](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Awhy-bricks-widely-used) — Civil Engineering Materials, chapter 3, asked 3×
- [Efflorescence test for bricks](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aefflorescence-test-brick) — Civil Engineering Materials, chapter 3
- [Compressive strength of Nepali bricks](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Abrick-compressive-strength-nepal) — Civil Engineering Materials, chapter 3

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