---
title: "Define pozzolanic materials"
subject: "Civil Engineering Materials"
chapter: 4
key: "semester_3/civil_engineering_materials:define-pozzolanic-materials"
source: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/define-pozzolanic-materials
site: BCT Engineering
---

# Define pozzolanic materials

Civil Engineering Materials · Chapter 4: Lime

- Asked in: 2080 Bhadra, 1 marks; 2079 Bhadra, 1 marks; 2078 Kartik, 1 marks; 2078 Bhadra, 1 marks; 2076 Asoj, 1 marks; 2074 Chaitra, 1 marks; 2069 Chaitra, 1 marks (asked 7 times)
- Video: [Pozzolanic Supplementary Cementitious Materials](https://www.youtube.com/watch?v=8N7YwRSNDhA) — ETHZ - Physical Chemistry of Building Materials
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/civil_engineering_materials/define-pozzolanic-materials
- Whole chapter: https://www.bctengineer.com/md/semester_3/civil_engineering_materials/chapter-4

## Question

Define pozzolanic materials.

## Short answer

Pozzolanic materials are siliceous or aluminous substances that have little cementing value alone, but in finely divided form and with moisture, they react with calcium hydroxide at ordinary temperature to form cementitious compounds. Examples include fly ash, volcanic ash, and silica fume.

## Answer

**Pozzolanic materials** are siliceous or aluminous materials that have little cementing value themselves, but in finely divided form and in the presence of moisture react chemically with calcium hydroxide (lime) at ordinary temperature to form compounds with cementing properties. Examples: fly ash, volcanic ash, surkhi, burnt clay, rice husk ash and silica fume.

## Check yourself

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

1. Pozzolanic materials react with:
   A. Calcium hydroxide in the presence of moisture
   B. Sulphuric acid
   C. Oil
   D. Dry sand
   Answer: A. They form cementing compounds. (Key point: Definition)

2. By themselves, pozzolanic materials have:
   A. High cementing value
   B. Little cementing value
   C. Very high strength
   D. None and cannot react
   Answer: B. They need fine division and lime. (Key point: Own cementing)

3. Which is a pozzolanic material?
   A. Granite
   B. Quicklime
   C. Fly ash
   D. Gypsum
   Answer: C. Others include surkhi and silica fume. (Key point: Examples)

## Related in Civil Engineering Materials

- [Why pozzolanic materials are used](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Awhy-pozzolanic-materials-used) — Civil Engineering Materials, chapter 4, asked 2×
- [Properties of pozzolanic materials](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aproperties-pozzolanic-materials) — Civil Engineering Materials, chapter 4