---
title: "Fat lime composition, properties, uses"
subject: "Civil Engineering Materials"
chapter: 4
key: "semester_3/civil_engineering_materials:fat-lime-composition-properties-uses"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/fat-lime-composition-properties-uses
site: BCT Engineering
---

# Fat lime composition, properties, uses

Civil Engineering Materials · Chapter 4: Lime

- Asked in: 2081 Bhadra, 3 marks
- Video: [fat Lime || Classification of lime || Lime || Building Material and Constructions.](https://www.youtube.com/watch?v=rg1HORjgqO0) — abhiyantriki pathshala
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/fat-lime-composition-properties-uses
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-4

## Question

Discuss the composition, properties and uses of fat lime.

## Short answer

Fat lime contains over 95% CaO, is white, slakes violently, sets slowly in air by carbonation, has high plasticity and low strength. Used for whitewashing, plaster, mortar with surkhi, bricks and in cement manufacture.

## Answer

**Fat lime** (high calcium, rich or pure lime) is obtained by burning nearly pure limestone.

#### Composition
Contains over 95% calcium oxide (CaO) with less than 5% of clay and other impurities.

#### Properties
- Pure white colour.
- Slakes vigorously with water, producing much heat and expanding to 2 to 2.5 times its volume.
- Sets and hardens slowly in air by absorbing CO₂ (carbonation); does not set under water.
- High plasticity and good workability.
- Low strength compared to hydraulic lime, and soluble in water.

#### Uses
1. Whitewashing and colour washing.
2. Plastering walls and as mortar for ordinary masonry in dry places.
3. Mixed with pozzolana (surkhi) for hydraulic mortar.
4. Making bricks, putty, and in the manufacture of cement and glass.

## Check yourself

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

1. Fat lime contains:
   A. 50% CaO
   B. Over 95% CaO
   C. Over 30% clay
   D. Over 95% clay
   Answer: B. Less than 5% impurities. (Key point: Composition)

2. Fat lime sets by:
   A. Hydration under water
   B. Cooling
   C. Absorbing CO2 (carbonation)
   D. Drying only
   Answer: C. It does not set under water. (Key point: Setting)

3. Fat lime is used for:
   A. Underwater foundations
   B. Reinforced concrete
   C. Bridge piers
   D. Whitewashing and plastering
   Answer: D. It is used in dry places. (Key point: Use)

## Related in Civil Engineering Materials

- [Hydraulic and fat lime properties](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Ahydraulic-fat-lime-properties) — Civil Engineering Materials, chapter 4
- [Types of lime, properties and uses](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Atypes-of-lime-uses) — Civil Engineering Materials, chapter 4, asked 3×
- [Properties and uses of lime](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aproperties-uses-of-lime) — Civil Engineering Materials, chapter 4, asked 2×
- [Fat lime versus hydraulic lime](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Afat-hydraulic-lime-difference) — Civil Engineering Materials, chapter 4, asked 3×
- [Storage and handling of fat lime](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Astorage-handling-fat-lime) — Civil Engineering Materials, chapter 4
- [Asphalt properties and uses](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aasphalt-properties-uses) — Civil Engineering Materials, chapter 10, asked 4×

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