---
title: "Physical properties of OPC and concrete behaviour"
subject: "Concrete Technology and Masonry Structure"
chapter: 1
key: "semester_5/concrete_technology_and_masonry_structure:cement-physical-properties"
source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/cement-physical-properties
site: BCT Engineering
---

# Physical properties of OPC and concrete behaviour

Concrete Technology and Masonry Structure · Chapter 1: Introduction to concrete and concrete materials

- Asked in: 2067 Magh (old course), 2+3 marks
- Video: [Unveiling the Power: Exploring the Properties of Cement](https://www.youtube.com/watch?v=H5QzyB11Pas) — Kamal Banerjee
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/cement-physical-properties
- Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-1

## Question

Write short notes on the physical properties of ordinary Portland cement and their effects on concrete behaviour.

## Short answer

F ineness affects hydration rate and bleeding; standard consistency indicates water demand; initial set allows placement time; soundness ensures volume stability; compressive strength defines grade; heat of hydration influences thermal cracking; specific gravity is ~3.15.

## Answer

Physical properties of OPC (tested as per IS 4031; limits as per IS 269:2015):

| Property | Requirement / typical | Effect on concrete behaviour |
|---|---|---|
| **Fineness** | Specific surface not less than 225 m$^2$/kg (Blaine); residue on 90 micron sieve about 10% | Finer cement hydrates faster: higher early strength and heat, better workability and less bleeding; but more shrinkage and cracking |
| **Standard consistency** | 26-33% water | Gives the water content for the Vicat tests; a high value means a higher water demand |
| **Setting time** | Initial not less than 30 min; final not more than 600 min | Initial set gives time for mixing, transport and placing; final set limits the time before forms can be removed and curing started |
| **Soundness** | Le Chatelier expansion not more than 10 mm; autoclave expansion not more than 0.8% | Excess free lime or MgO causes later expansion and cracking |
| **Compressive strength** | 3, 7 and 28-day strengths: for 43 grade, 23, 33 and 43 MPa | Basis for the concrete grade |
| **Heat of hydration** | OPC typically about 80-90 cal/g at 7 days (no limit in IS 269); low-heat cement (IS 12600) is limited to 65 cal/g at 7 days and 75 cal/g at 28 days | High heat causes thermal cracking in mass concrete |
| **Specific gravity** | About 3.15 | Used in mix design and volume calculations |

Also, the loss on ignition (maximum 5%) and insoluble residue (maximum 4%) indicate quality.

## Check yourself

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

1. Finer cement results in:
   A. Faster hydration, higher early strength, more shrinkage
   B. Slower hydration
   C. Lower early strength
   D. Less heat
   Answer: A. Fineness measured by Blaine. (Key point: Fineness)

2. Le Chatelier test checks:
   A. Strength
   B. Expansion due to free lime or MgO
   C. Setting time
   D. Colour
   Answer: B. Limit is 10 mm. (Key point: Soundness)

3. IS 269 initial setting time of OPC is:
   A. Not more than 30 min
   B. 10 hours
   C. Not less than 30 min
   D. 60 min exactly
   Answer: C. Final is not more than 600 min. (Key point: Setting time)

## Related in Concrete Technology and Masonry Structure

- [Microstructure of ordinary Portland cement](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Amicrostructure-opc) — Concrete Technology and Masonry Structure, chapter 2
- [OPC versus PPC](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aopc-vs-ppc) — Concrete Technology and Masonry Structure, chapter 1
- [Hardened concrete properties; elastic behaviour](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ahardened-properties-elastic-behaviour) — Concrete Technology and Masonry Structure, chapter 4
- [Physical causes of concrete deterioration](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aphysical-causes-deterioration) — Concrete Technology and Masonry Structure, chapter 6, asked 6×
- [Theoretical strength of moist cured concrete (1 kg cement)](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Atheoretical-strength-1kg-cement) — Concrete Technology and Masonry Structure, chapter 4
- [Properties of hardened concrete](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Ahardened-concrete-properties) — Concrete Technology and Masonry Structure, chapter 4, asked 3×

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- [Types of stresses in cement concrete pavement](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Arigid-pavement-stresses) — Transportation Engineering II, chapter 2, asked 2×
- [Physical properties of minerals](https://www.bctengineer.com/question.md?key=semester_3%2Fengineering_geology_i%3Aphysical-properties-of-minerals) — Engineering Geology I, chapter 3, asked 6×
- [Rate analysis: plain cement concrete (1:3:4)](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Arate-pcc-1-3-4) — Estimating and Costing, chapter 4