Method of test for building limes, Part 1: Determination of insoluble residue, loss on ignition, insoluble matter,silicon dioxide, ferric and aluminium oxide, calcium oxide and magnesium oxide

IS 6932 Part 1 - Scope & Key Specifications

Scope (Clause 1.1):
This part covers methods of tests for building lime to determine:

• Insoluble residue in dilute acid & alkali
• Loss on ignition
• Insoluble residue in hydrochloric acid
• Silicon dioxide (SiO₂)
• Ferric oxide (Fe₂O₃) & Aluminium oxide (Al₂O₃)
• Calcium oxide (CaO)
• Magnesium oxide (MgO)

Key Formula (Clause 8.2.2.1):

Calcium oxide equivalent of potassium permanganate solution (E) in g/ml:

[ E = \frac{\text{Calcium oxide equivalent of KMnO}_4 \text{ solution}}{\text{Volume of KMnO}_4 \text{ solution (ml)}} ]

Where:

• (I') = ml of KMnO₄ required for titration of 0.7560 g sodium oxalate

Additional Test Method:

• EDTA Method (Clause 9.4) for non-hydraulic lime per IS 5949-1970 (volumetric determination of Ca & Mg).

Notes:

• Results rounding as per IS 2-1960.
• Updated references: IS 2250-1981 for mortar preparation.

This standard ensures chemical quality control of building lime for construction applications.

IS 6932 Part 1: Treatment of the Sample - Key Points & Procedure

Sample Preparation

• Follow Clause 7.2 of IS 712-1973 for sample preparation before testing.

Filtrate Preparation (Clause 8.1.2.1)

• Combine filtrate as per 7.2.2.
• Dilute to 500 ml with distilled water.
• Use 25 ml aliquot for analysis (Clause 8.2).

Oxalate Precipitation & Titration (Clause 8.2.2)

1. Take 100 ml aliquot from the second half of filtrate.
2. Make alkaline with ammonium hydroxide.
3. Boil vigorously.
4. Add 35 ml boiling saturated ammonium oxalate solution.
5. Stir and allow precipitate to settle.
6. Filter using 11 cm filter paper or Gooch/Sintered glass crucible.
7. Wash precipitate 10 times with hot water (max 125 ml).
8. Transfer filter paper with precipitate to beaker; wash precipitate off paper.
9. Add 50 ml dilute sulphuric acid, dilute to 250 ml with hot water.
10. Heat to 80-90°C.
11. Titrate with standard potassium permanganate until pink endpoint.
12. Drop folded filter paper into titration; pink color disappears.
13. Continue titration dropwise until pink endpoint reappears.

Summary Table for Key Volumes & Reagents

flowchart TD
    A[Sample Preparation (IS 712-1973)] --> B[Filtrate combined & diluted to 500 ml]
    B --> C[Take 25 ml aliquot for analysis]
    B --> D[Take 100

IS 6932 Part 1: Determination of Insoluble Residue Including Silicon Dioxide in HCl

Key Points & Specifications:

• Reagent: Use distilled water as per IS 1070-1960t for all reagent preparations (Clause 2.2).

• Sample Preparation: The sample mass is taken as per Clause 5.2.1 (not detailed here).

• Determination Procedure:

  1. Treat the sample with hydrochloric acid (HCl) to dissolve soluble components.
  2. Filter and wash the residue.
  3. Dry and weigh the insoluble residue, which includes silicon dioxide (SiO₂).

• Result Expression (Clause 5.3):

  [ \text{Insoluble residue %} = \frac{\text{Mass of dried insoluble residue}}{\text{Mass of sample taken}} \times 100 ]

• Silicon Dioxide Determination (Clause 6): Usually involves further treatment of the insoluble residue with hydrofluoric acid (HF) or other methods to isolate SiO₂ content specifically, but details are not provided here.

Summary Table:

flowchart TD
    A[Sample] --> B[Treat with HCl]
    B --> C[Filter residue]
    C --> D[Dry residue]
    D --> E[Weigh residue]
    E --> F[Calculate % insoluble residue]

For detailed silicon dioxide isolation, refer to specialized chemical methods beyond this clause.

IS 6932 Part 1: Determination of Loss on Ignition (LOI)

Key Specifications & Procedure

• Sample size: 1 g of prepared sample
• Crucible: Weighed platinum crucible with lid
• Ignition temperature: ≥ 1000°C
• Ignition: Ignite to constant mass

Formula for Loss on Ignition (Clause 4.2)

[ \text{Loss on Ignition (%)} = 100 \times \frac{M_1 - M_2}{M_1} ]

• (M_1) = Mass of original sample
• (M_2) = Mass after ignition

Reporting (Clause 3.3)

• Insoluble residue is expressed as a percentage on ignited mass basis.
• Use LOI to adjust calculations for insoluble matter.

Summary Table

flowchart TD
    A[Weigh 1g Sample (M1)] --> B[Place in Pt Crucible]
    B --> C[Ignite at ≥1000°C to Constant Mass]
    C --> D[Weigh Residue (M2)]
    D --> E[Calculate LOI: 100*(M1 - M2)/M1]
    E --> F[Report LOI %]

This method ensures accurate determination of volatile content lost on ignition, critical for material characterization.

IS 6932 Part 1: Determination of Insoluble Matter Including Silicon Dioxide

Key Specifications & Formulas

• Sample basis: Insoluble matter including SiO₂ is expressed as % by mass of the original sample (Clause 5.3).

• Loss on Ignition (LOI):
  [ \text{LOI (%)} = 100 \times \frac{M_1 - M_2}{M_1} ] where:

  • (M_1) = mass of original sample
  • (M_2) = mass after ignition (Clause 4.2)

• Determination of Insoluble Matter including Silicon Dioxide:
  The residue after acid digestion and filtration is dried, weighed, and the insoluble matter (including SiO₂) is calculated as:
  [ \text{Insoluble matter (%)} = \frac{\text{Mass of residue}}{\text{Mass of original sample}} \times 100 ]

Summary Table

flowchart TD
    A[Original Sample] --> B[Ignition at specified temp]
    B --> C[Mass after ignition (M2)]
    A --> D[Acid digestion + filtration]
    D --> E[Drying & weighing residue]
    E --> F[Calculate Insoluble Matter %]
    B --> G[Calculate LOI %]

This ensures precise quantification of insoluble residue including silicon dioxide per IS 6932 Part 1.

IS 6932 Part 1: Determination of Silicon Dioxide (SiO₂)

Key Formulas:

• Let:

  • ( m_s ) = mass of the original sample (Clause 5.2.1)
  • ( m_r ) = mass after treatment (Clause 6.2)

• Mass of Silicon Dioxide: [ m_{SiO_2} = m_s - m_r ]

• Percentage of Silicon Dioxide: [ % SiO_2 = \left(\frac{m_{SiO_2}}{m_s}\right) \times 100 ]

Specifications:

• The insoluble matter including SiO₂ is reported as a percentage by mass of the original sample.
• The mass difference between treated and untreated samples corresponds to SiO₂ content.

Summary Table:

flowchart TD
    A[Sample mass \(m_s\)] --> B[Treatment process]
    B --> C[Mass after treatment \(m_r\)]
    C --> D[Calculate \(m_{SiO_2} = m_s - m_r\)]
    D --> E[Calculate \(\% SiO_2 = (m_{SiO_2}/m_s) \times 100\)]
    E --> F[Report % Silicon Dioxide]

This method ensures accurate quantification of SiO₂ as per IS 6932 Part 1.

IS 6932 Part 1: Key Points on Determination of Ferric and Aluminium Oxides

1. Determination of Ferric Oxide (Clause 7.4)

• Ferric oxide (Fe₂O₃) is determined by chemical precipitation and ignition.
• The precipitate is ignited at 1100°C in a platinum crucible to constant weight.
• The mass obtained corresponds to combined ferric and aluminium oxides.

2. Determination of Aluminium Oxide (Clause 7.5)

• Total mass of ferric and aluminium oxides is obtained first (Clause 7.3).

• Aluminium oxide (Al₂O₃) content is found by subtracting ferric oxide mass from the total:

  [ \text{Mass of } Al_2O_3 = \text{Mass of } (Fe_2O_3 + Al_2O_3) - \text{Mass of } Fe_2O_3 ]

3. Ignition Procedure (Clause 7.2.3)

• Ignite moist filter paper with precipitate in a weighed platinum crucible at 1100°C until constant weight.
• This gives the combined mass of Fe₂O₃ and Al₂O₃.
• Note: Small amounts of P₂O₅, Mn₃O₄, TiO₂ may be present in some limes.

Summary Table for Oxide Determination

This method ensures accurate quantification of Fe₂O₃ and Al₂O₃ in lime samples per IS 6932 Part 1.

IS 6932 Part 1: Determination of Calcium Oxide (CaO) Content

Key Specifications & Procedure Highlights:

• Sample basis: CaO content reported as % mass of the sample (Clause 8.1.3).
• Precipitate treatment: After settling, filter, wash residue with 0.1% ammonium oxalate, then ignite in a weighed platinum crucible to constant mass (Clause 8.1.2.4).
• Mass difference: Ignition mass difference = mass of CaO in the sample.
• Titration equivalence:
  1 mL of standard potassium permanganate ≈ 0.005 g CaO (Clause 8.2.2.1).

Calculation Formula:

[ \text{CaO %} = \frac{\text{Mass of CaO (g)}}{\text{Mass of sample (g)}} \times 100 ]

Where:

• Mass of CaO = Ignition mass difference or calculated from titration volume × 0.005 g/mL

Summary Table:

flowchart TD
    A[Sample Preparation] --> B[Precipitate Settles]
    B --> C[Filter & Wash with 0.1% Ammonium Oxalate]
    C --> D[Ignite in Platinum Crucible]
    D --> E[Calculate Mass Difference = CaO Mass]
    E --> F[Calculate % CaO]
    F --> G[Report Results]

This method ensures accurate quantification of CaO content per IS 6932 Part 1.

Determination of Magnesium Oxide (MgO) as per IS 6932 Part 1

Key Formula (Clause 9.3)

[ \text{Magnesium Oxide (% by mass)} = \frac{A}{B} \times 36.2 ]

• A = Mass of magnesium pyrophosphate (Mg₂P₂O₇) obtained after ignition.
• B = Mass of the ignited sample (aliquot used for CaO estimation).

Notes:

• The MgO content is expressed as a percentage of the mass of the sample taken under Clause 5.2.1 (Clause 9.3.1).
• For non-hydraulic lime, the EDTA method (IS 5949-1970) can be used (Clause 8.3).
• The method involves first determining calcium oxide content (Clause 8) before MgO estimation.
• Aluminium oxide content is corrected by subtracting ferric oxide mass from combined Fe₂O₃ + Al₂O₃ (Clause 7.5).

Summary Table:

This formula and approach ensure accurate quantification of MgO in lime samples per IS 6932 Part 1.

IS 6932 Part 1: Report of Test Results - Key Points

1. Calcium Oxide Content (Clause 8.1.3)

   • Report as % mass of the sample (per 5.2.1).

2. Ferric and Aluminium Oxide Content (Clause 7.3)

   • Report as % mass of the sample (per 5.2.1).

3. Magnesium Oxide Content (Clause 9.3)

   • Calculate using:
     [ \text{MgO % by mass} = \frac{A}{B} \times 36.2 ] Where:
     • ( A ) = mass of magnesium pyrophosphate
     • ( B ) = mass of ignited sample (aliquot for CaO estimation, 3.1.2.1)

Summary Table for Reporting

This ensures uniformity and clarity in test result reporting per IS 6932 Part 1.