Material Testing - MAGNESIA ANALYSIS.pdf

Test on Cement

1. CHEMICAL TEST: SULFUR

2. Based on ASTM C114 and ASTM D7348
CHEMICAL TEST: MAGNESIA
CHEMICAL TEST: SULFUR
TRIOXIDE
LOSS ON IGNITION

3. MAGNESIA ANALYSIS
(section 14)
Thistestmeasureshowmuchmagnesium
oxide(MgO)isincement.Magnesiumoxide
isanaturalpartofcementandcanaffecthow
stronganddurablethecementwillbewhen
usedinconstruction.

4. Apparatus and Materials
•Hydrochloric acid (HCl)
•Ammonium phosphate solution
Ammonium hydroxide (NH₄OH)
•Platinum or porcelain crucible
•Balance for weighing
•Filter Paper

5. Apparatus and Materials
Platinum crucible Filter Paper Balance

6. Procedure
•Add acid–Take the liquid left after testing for calcium oxide
(CaO). Add hydrochloric acid (HCl)and heat it until only 250 mL
of liquidis left. Cool it down in room temp.
•Add chemicals–Pour in 10 mL of ammonium phosphate
solution (100 g/L)and 30 mL of ammonium hydroxide while
stirring well. Mix the solution continuously for 10 to 15 minutes
after adding NH₄OH.
•Let it sit–Leave the solution undisturbed for at least 8 hours
in a cool place.

7. Procedure
•Filter the solid–Pour the solution through filter paper to separate the
solid part. Wash the solid 5 to 6 timesusing diluted ammonium
hydroxide (NH₄OH, 1 part NH₄OH + 20 parts water).
•Heat slowly–Place the solid in a platinum or porcelain crucible.
Heat it gently first until the filter paper turns black (charred).
•Burn completely–Then, heat it at 1100°Cfor 30 to 45 minutesuntil
the remaining material turns into magnesium pyrophosphate (Mg₂P₂O₇).
•Weigh the final product–Measure the weight of the remaining solid to
determine the amount of magnesium oxide (MgO).

8. Formula and Sample Calculation
Suppose a test gives 0.200 gof Mg₂P₂O₇:
MgO,% = W x 72.4 =
MgO,% =0.200×72.4 =14.48%

9. THE STANDARD
According to ASTM C150, which is commonly used for Portland
cement:
Magnesium Oxide (MgO) Limit:
≤ 6.0% for most Portland cement types

10. WHAT TO DO IF SAMPLE FAILS
•Verify the Results
•Modify Cement Usage
•Reject or Reprocess the Cement

11. SULFUR TRIOXIDE
TEST (section 15.1)
This test checks how much sulfur trioxide (SO₃)
is in cement. SO₃ is an important chemical
because it helps cement harden properly, but
too much of it can be a problem.

12. Apparatus and Materials
•Hydrochloric acid (HCl)
•Barium chloride (BaCl₂) solution
•Filter paper
•Platinum crucible
•Heating Apparatus
•Desiccator
•Balance

13. Apparatus and Materials
Platinum crucible DesiccatorFurnace

14. Procedure
•Mix sample with water and acid–Take 1 g of the cement
sampleand mix it with 25 mL of cold water. Stir well while adding 5
mL of hydrochloric acid (HCl). Dissolve the cement with a glass
rod
•Dilute and heat–Add more water until the total volume is 50 mL.
Heat the solution (without boiling) for 15 minutes.
•Filter the solid, Dilute again and boil–Pour the solution through
filter paper to remove undissolved parts. Wash the solid with hot
waterto clean it.Add more water to make 250 mLof liquid and
bring it to a boil.

15. Procedure
•Add barium chloride–Slowly add 10 mL of hot barium chloride (BaCl₂,
100 g/L)drop by drop while stirring.Keep the solution warm (just below
boiling) for 12 to 24 hoursso the solid (precipitate) forms properly. Make
sure the liquid level stays between 225 and 260 mLby adding water if
needed.
•Filter and clean the solid–Pour the solution through a special filter paper
to collect the solid. Wash the solid thoroughly with hot water.
•Burn off the paper–Place the filter paper with the solid in a weighed
platinum crucible. Heat slowly until the paper turns black and burns away
completely.
•Final heating and weighing–Heat the remaining solid at 800–900°C,
then cool it in a desiccator. Weigh the final solid to determine the sulfur
trioxide (SO₃) content.

16. Formula and Sample Calculation
If 0.150 gof BaSO₄ is obtained:
SO3, %= W x 34.3 =
SO3, %=0.150g×34.3= 5.15%

17. THE STANDARD
According to ASTM C150, which is commonly used for Portland
cement:
Sulfur Trioxide (SO₃) Limit:
•≤ 3.0%for Type I cement (Portland Cement)
•≤ 3.5%for Type II cement (Portland Pozzolana Cement)
•≤ 4.5%for cement with added limestone

18. WHAT TO DO IF SAMPLE FAILS
•Verify the Results
•Modify Cement Usage
•Reject or Reprocess the Cement

19. LOSS ON
IGNITION
(LOI)
ASTM D7348

20. Loss on Ignition (LOI) is a test used to
determine the mass loss of solid
combustion residues when heated at
high temperatures in an air or oxygen
atmosphere. The mass loss represents
the removal of moisture, carbon,
sulfur, and other volatile substances.

21. APPARATUS AND MATERIALS/REAGENT
Furnace Drying Oven Crucibles

22. APPARATUS AND MATERIALS/REAGENT
Balance Nitrogen Air

23. PROCEDURE USING
SINGLE STEP METHOD
-Weigh 1 gram of the sample and place it in a crucible.
-Use oxygen or air in the furnace. Heat gradually to 500°C in 1 hour.
-Continue heating:
For Method A: Increase to 750°C over another hour.
For Method B: Increase to 950°C over another hour.
-Keep the sample at the final temperature until its weight stops
changing (or for 2 more hours).

24. PROCEDURE USING
DOUBLE STEP METHOD
Step 1 –Remove Moisture:
Weigh 1 gram of the sample and place it in a crucible.
Heat in a drying oven at 104-110°C for 1 hour. Cool and weigh again.
Step 2 –Determine LOI:
-Change the furnace gas to oxygen or air. Gradually heat to 500°C in 1 hour.
-Continue heating:
Method A:
Method B:
-Maintain this temperature until the sample reaches a stable weight (or for 2
more hours).

25. FORMULA AND
SAMPLE
CALCULATION
Assume:
•Initial sample mass W=1.0g
•Sample mass after heating at 750°C B=0.85g
LOI=(1.00−0.85)/1.00×100=15.00%

26. THE STANDARD
Cement Industry (ASTM C114, EN 196-2)
•LOI at 950°Cis used to measure carbonates, sulfates, and organic matter.
•Acceptable LOI range: 0.5% to 5%(varies by cement type).
•High LOI may indicate excess limestone or organic impurities, affecting
cement strength.
Coal and Power Plants (ASTM D7348, ASTM D3174)
•LOI at 750°Chelps determine unburned carbon contentin fly ash.
•A low LOI (≤ 5%) is ideal for efficient combustionin power plants.
•High LOI indicates poor fuel efficiencyor incomplete combustion.

27. WHAT TO DO IF THE SAMPLE FAILS
•Check Sample Preparation–Ensure proper grinding and weighing.
•Verify Furnace Conditions–Maintain accurate temperature and airflow.
•Investigate Contamination–Identify potential sources affecting results.
•Repeat the Test–Conduct multiple trials to confirm consistency.

28. MTS FORM NO. 12

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