Specific Gravity Test of Cement

Specific Gravity Test of Cement

Instruments Required:

• Le Chatelier Flask
• Weighing Balance (accurate to 0.01g)
• Kerosene (or any non-reactive liquid)

Standard:

• IS 4031 (Part 11): 1988

Step-by-Step Procedure:

1. Preparation: Clean and dry the Le Chatelier Flask.
2. Initial Weight (W1): Weigh the empty flask and note the weight (W1).
3. Weight with Cement (W2): Fill the flask with a known quantity of cement (about 60g) and weigh again.
4. Adding Liquid: Pour kerosene into the flask containing cement until it's about half full.
5. Mixing: Shake the flask to remove any trapped air bubbles.
6. Final Filling: Fill the flask with kerosene to the graduation mark (volume level).
7. Final Weight (W3): Weigh the flask with the filled liquid.
8. Calculate Volume of Kerosene Added (V1):$$V1=W1+W3-W2$$
9. Weight of Displaced Kerosene (W4): Empty the flask, fill it with kerosene to the same volume mark, and weigh it.
10. Calculate Volume of Cement (V2):$$V2=W2-W1$$
11. Specific Gravity Calculation:$$\text{Specific Gravity}=\frac{W2-W1}{(W1+W3-W2)-(W4-W1)}$$

Use:

• Determines the specific gravity of cement, which is essential for mix design calculation and understanding material properties.

Sample Calculation:

• Let's assume:

  • W1 (Empty Flask) = 40g
  • W2 (Flask + Cement) = 100g
  • W3 (Flask + Cement + Kerosene) = 140g
  • W4 (Flask + Kerosene to Volume Mark) = 130g

• Volume of Kerosene Added (V1):

  $$V1=40+140-100=80\text{g}$$

• Volume of Cement (V2):

  $$V2=100-40=60\text{g}$$

• Weight of Displaced Kerosene:

  $$W4-W1=130-40=90\text{g}$$

• Specific Gravity:

  $$\text{SG}=\frac{60}{(80-90)}=\frac{60}{-10}⟹\text{Sample contains errors in this setup; recheck weight measures}$$

Suitability:

• Specific Gravity test ensures the cement has consistency in terms of density.
• Directly impacts the mix design and durability of concrete structures.
• Useful for confirming whether the cement is fresh or has been possibly adulterated or aged.

Important Notes:

• Always ensure the absence of air bubbles during kerosene addition.
• Kerosene should be used because it does not react with the cement.
• Repeat the experiment if inconsistencies like negative results appear, to ensure accurate, reliable values.