---
title: "Efflorescence in bricks"
subject: "Civil Engineering Materials"
chapter: 3
key: "semester_3/civil_engineering_materials:efflorescence-in-brick"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/efflorescence-in-brick
site: BCT Engineering
---

# Efflorescence in bricks

Civil Engineering Materials · Chapter 3: Clay Products

- Asked in: 2076 Asoj, 1 marks; 2074 Asoj, 1 marks (asked 2 times)
- Video: [Efflorescence in Bricks](https://www.youtube.com/watch?v=2pu2SxAK-Q8) — NCTEL
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/efflorescence-in-brick
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-3

## Question

What is efflorescence in brick?

## Short answer

Efflorescence is a whitish deposit of soluble salts on brick surfaces due to water evaporation, spoiling appearance and potentially causing spalling.

## Answer

**Efflorescence** is the whitish crystalline deposit of soluble salts (sulphates of sodium, calcium, magnesium) that appears on the surface of bricks and brick walls when water evaporates. It spoils the appearance and can cause spalling.

## Check yourself

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

1. Efflorescence appears as:
   A. Black soot
   B. A whitish crystalline deposit on the surface
   C. Green moss
   D. Red stains
   Answer: B. Soluble salts remain when water evaporates. (Key point: Appearance)

2. Salts causing efflorescence are mainly:
   A. Chlorine gas
   B. Iron
   C. Sulphates of sodium, calcium and magnesium
   D. Silica
   Answer: C. These soluble salts crystallise on the surface. (Key point: Salts)

3. Efflorescence:
   A. Increases strength
   B. Improves colour
   C. Has no effect
   D. Spoils appearance and can cause spalling
   Answer: D. It damages the surface. (Key point: Effect)

## Related in Civil Engineering Materials

- [Efflorescence test for bricks](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aefflorescence-test-brick) — Civil Engineering Materials, chapter 3
- [Efflorescence causes and test](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aefflorescence-causes-lab-test) — Civil Engineering Materials, chapter 3
- [Constituents of brick earth and functions](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aconstituents-brick-earth-functions) — Civil Engineering Materials, chapter 3, asked 9×
- [Harmful ingredients in brick earth](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aharmful-ingredients-brick-earth) — Civil Engineering Materials, chapter 3, asked 3×
- [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×
- [Preparation of clay for bricks](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aclay-preparation-for-bricks) — Civil Engineering Materials, chapter 3

## Related in other subjects

- [Compressive strength test and classification of bricks](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Abrick-compressive-strength-test-classification) — Design of Timber and Masonry Structures, chapter 8
- [Brick and mortar for 230 mm wall (100 kN/m)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Awall-eccentric-230mm-100kn-5m) — Concrete Technology and Masonry Structure, chapter 8, asked 7×
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- [Brick and mortar for 250 mm wall (350 kN/m)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Awall-eccentric-250mm-350kn) — Concrete Technology and Masonry Structure, chapter 8, asked 7×