---
title: "Properties of mortar"
subject: "Building Technology"
chapter: 3
key: "semester_6/building_technology:properties-of-mortar"
source: https://www.bctengineer.com/q/semester_6/building_technology/properties-of-mortar
site: BCT Engineering
---

# Properties of mortar

Building Technology · Chapter 3: Mortars & Masonry works

- Asked in: 2079 Jestha, 2 marks; 2078 Poush, 2 marks; 2075 Bhadra, 3 marks (asked 3 times)
- Video: [Mortar Qualities and properties](https://www.youtube.com/watch?v=i505PjQegmA) — construct SKILLS
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/properties-of-mortar
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-3

## Question

What are the properties of mortar?

## Answer

**Mortar** is a paste of binding material (cement, lime or mud), fine aggregate (sand) and water, used to join bricks or stones, and for plastering and pointing. A good mortar should have the following properties.

1. **Workability**: It should be easily mixed, spread, and applied without segregation; it should stay plastic long enough for placing.
2. **Adhesion (bond strength)**: Good bond with bricks, stones and the surfaces.
3. **Strength**: Sufficient compressive strength to carry the load of masonry. Cement mortar 1:4 has 7 to 8 N/mm² at 28 days (IS 2250).
4. **Durability**: Resists weather, moisture, frost and chemicals.
5. **Water retentivity**: It should not lose water rapidly to dry bricks; this keeps the hydration complete.
6. **Setting time and hardening**: Initial set not before 30 minutes (cement); it should harden at a suitable rate.
7. **Imperviousness**: Low permeability so that water does not enter the wall.
8. **Fire resistance**.
9. **Low shrinkage and cracking**.
10. **Economy**, and good appearance of the joints.
11. **Proper fineness of sand** (graded, free of clay, silt, organic matter).

## Check yourself

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

1. Workability of mortar means:
   A. Easily mixed and spread without segregation
   B. Never needs water
   C. Is very strong
   D. Hardens instantly
   Answer: A. It should stay plastic long enough for placing. (Key point: Workability)

2. Water retentivity prevents:
   A. Cracks in bricks
   B. Sand from being used
   C. Dry bricks from sucking water rapidly, keeping hydration complete
   D. Mortar from hardening
   Answer: C. Retained water allows complete hydration. (Key point: Water retentivity)

3. Initial set of cement mortar should be:
   A. Not before 30 minutes
   B. Within 1 minute
   C. Immediately
   D. After 24 hours
   Answer: A. Time is needed to place and finish. (Key point: Setting time)

## Related in Building Technology

- [Functions and properties of mortar](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amortar-functions-properties) — Building Technology, chapter 3
- [Mortar properties; cement and sand for 10 cum](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Amortar-quantity-10cum) — Building Technology, chapter 3

## Related in other subjects

- [Properties of mortar](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Aproperties-of-mortar) — Civil Engineering Materials, chapter 6, asked 3×
- [Cement and mud mortar properties, uses](https://www.bctengineer.com/question.md?key=semester_3%2Fcivil_engineering_materials%3Acement-mud-mortar-properties-uses) — Civil Engineering Materials, chapter 6