Reviewed by Er. Inderjit Sharma (Retd.), Punjab PWD
What is specific gravity of cement? It tells you how heavy the cement is compared with the same volume of water. Ordinary Portland cement is about 3.15 times heavier than water.
How is it measured? A known weight of cement is added to kerosene in a Le Chatelier flask. The rise in level gives the volume of the cement. (Kerosene is used instead of water because cement reacts with water.)
Why it matters: it’s needed for concrete mix design and is a quick check for adulteration or the wrong type of cement. This guide follows IS 4031 (Part 11).
The Le Chatelier Flask
The Idea Behind the Test
Apparatus Required
Le Chatelier flask
250 ml flask with a graduated neck (0–1 ml and 18–24 ml).
Balance (0.01 g)
Weighs the cement accurately.
Kerosene (water-free)
Doesn’t react with cement, unlike water.
Water bath & thermometer
Keeps the flask at a steady temperature for both readings.
Funnel
Helps add cement without spilling or clogging the neck.
Procedure
- Clean and dry the Le Chatelier flask completely.
- Fill it with kerosene (free of water) to a point between the 0 and 1 ml marks. Dry the inside of the neck above the liquid.
- Place the flask in a water bath at room temperature until the temperature is steady, then note the first reading: V1.
- Weigh about 64–70 g of cement: W. Add it to the flask in small amounts, so it doesn’t stick to the neck or block it.
- Put the stopper on and roll the flask gently (tilted) until no more air bubbles rise.
- Put it back in the water bath at the same temperature, let the cement settle, and note the final reading: V2.
- Do at least two tests and report the mean.
Calculation
W = weight of cement (g); V2 − V1 = volume of kerosene pushed up (ml), which equals the volume of cement. Because 1 ml of water weighs 1 g, this gives the specific gravity directly. Report to two decimal places.
📝 Worked example
W = 64.00 g, V1 = 0.40 ml, V2 = 20.70 ml
Volume = 20.30 ml
SG = 64.00 ÷ 20.30 = 3.15 ✓ (typical for OPC)
Try It: Specific Gravity Calculator
Enter your readings. The values filled in are the worked example.
Bonus: volume of cement in 1 m³ of concrete
Precautions
💧 Dry flask, water-free kerosene
Any water reacts with the cement and spoils the result. Dry the flask fully before starting.
🌡️ Same temperature
Take V1 and V2 at the same temperature (use a water bath); kerosene expands with heat.
🫧 Remove all air
Roll the flask until no bubbles rise. Trapped air makes the volume look larger and the SG lower.
🧹 Don’t lose cement
Add cement slowly with a funnel; cement stuck on the neck or spilled outside gives a wrong result. Keep kerosene away from flames.
Practical Tips for Site Engineers
1. Typical Values
| Cement | Typical specific gravity |
|---|---|
| OPC (33, 43, 53) | 3.10–3.20 (commonly 3.15) |
| PPC (fly ash based) | 2.80–3.00 |
| PSC (slag cement) | 2.85–3.05 |
Typical ranges only; actual values depend on the brand and blend.
2. Good Site Habits
- Use the tested value in mix design: IS 10262 needs the specific gravity of cement to work out volumes. Use the value for the actual cement, not a guess.
- Low SG is a warning: OPC giving much less than 3.10 may be mixed with fly ash or other material, or may have absorbed moisture. Check further (fineness, setting time, strength).
- Know your cement type: PPC and PSC naturally have lower values than OPC; compare with the right range.
- Test fresh samples: keep the sample in an airtight container; moisture-affected cement gives lower values.
- Retest when the brand or plant changes, and keep the result with the cement test records.
Key Takeaways
- Specific gravity = how heavy cement is compared with water; OPC is about 3.15.
- Le Chatelier flask with kerosene: read V1, add W (about 64–70 g) of cement, remove air, read V2.
- SG = W ÷ (V2 − V1); take both readings at the same temperature.
- Typical: OPC 3.10–3.20, PPC 2.80–3.00, PSC 2.85–3.05.
- On site: use the tested value in mix design; a low value for OPC is a warning of adulteration or moisture.
References: IS 4031 (Part 11): Determination of Density of Hydraulic Cement; IS 10262: Concrete Mix Proportioning – Guidelines; IS 269 / IS 1489 / IS 455: Cement Specifications.