---
title: "Quick lime versus hydraulic lime"
subject: "Civil Engineering Materials"
chapter: 4
key: "semester_3/civil_engineering_materials:quick-lime-hydraulic-lime-difference"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/quick-lime-hydraulic-lime-difference
site: BCT Engineering
---

# Quick lime versus hydraulic lime

Civil Engineering Materials · Chapter 4: Lime

- Asked in: 2073 Shrawan, 2 marks
- Video: [The Ultimate Guide to Mastering the Lime / Quick lime: Everything You Need to Know!](https://www.youtube.com/watch?v=YJIIvrQzCf8) — MFA Civil Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/quick-lime-hydraulic-lime-difference
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-4

## Question

Differentiate between quick lime and hydraulic lime.

## Short answer

Quicklime is pure CaO, white, slakes violently, sets in air, low strength. Hydraulic lime contains silicates and aluminates, is grey, slakes slowly, sets under water, higher strength.

## Answer

| Basis | Quick lime | Hydraulic lime |
|---|---|---|
| Chemical form | Calcium oxide (CaO) | CaO with silicates and aluminates of calcium |
| Source | Pure limestone | Limestone with 5-30% clay |
| Slaking | Violent with great heat and swelling | Slow with little heat |
| Setting | Slakes first then sets in air | Sets under water and in damp places |
| Strength | Low | Higher |
| Colour | White | Grey or yellowish |
| Use | Whitewash, plaster | Mortar in wet places, foundations |

## Check yourself

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

1. Quick lime is:
   A. Silicates
   B. Ca(OH)2
   C. CaCO3
   D. CaO
   Answer: D. Hydraulic lime has silicates and aluminates. (Key point: Chemical form)

2. Quick lime slakes:
   A. Violently with great heat
   B. Slowly
   C. Never
   D. Without heat
   Answer: A. Hydraulic slow. (Key point: Slaking)

3. Hydraulic lime sets:
   A. Only in air
   B. Under water
   C. Never
   D. After burning
   Answer: B. Quick lime must slake first. (Key point: Setting)

## Related in Civil Engineering Materials

- [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×
- [Hydrated versus hydraulic lime](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Ahydrated-hydraulic-lime-difference) — Civil Engineering Materials, chapter 4
- [Define quick lime](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Adefine-quick-lime) — Civil Engineering Materials, chapter 4, asked 2×
- [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
- [Short note: hydraulic lime](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Ahydraulic-lime-short-note) — Civil Engineering Materials, chapter 4
- [Types of hydraulic lime](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Atypes-hydraulic-lime) — Civil Engineering Materials, chapter 4

## Related in other subjects

- [Permeability versus hydraulic conductivity](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Apermeability-versus-hydraulic-conductivity) — Engineering Geology I, chapter 6
- [Critical gradient; quick condition in sand](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Acritical-hydraulic-gradient-quick) — Soil Mechanics, chapter 6