Method for colourimetric analysis of hydraulic cement

IS 12423: Scope - Key Specifications & Calibration Procedures

IS 12423 focuses on chemical analysis methods for cement, including sulfate and ferric oxide content.

Important Notes on Values:

• Final test or analysis values must be rounded per IS 2-1960.
• Retain the same number of significant digits as in the standard.

Calibration for Sulfate (Clause 7.9.5)

• Pipette volumes: 2.5, 5, 7.5, 12.5, 17.5, 20 ml (and double for another solution)
• Add sequentially:
  • 10 ml dimethyl formamide
  • 15 ml stabilized barium chloride
• Make up to 100 ml with distilled water.
• Measure optical density at 502 nm after 5 mins.
• Subtract blank optical density.
• Plot optical density vs. sulfate concentration (ppm) for calibration curve.

Calibration for Ferric Oxide (Clause 7.6.3)

• Pipette volumes: 2, 4, 6, 8, 10, 12, 16 ml of 100 ppm Fe2O3 solution.
• Add sequentially:
  • 5 ml ammonium chloride
  • 6 ml sulphosalicylic acid (10 ml for PPC)
• Add ammonia until color changes to bright yellow + 1 ml extra.
• Make up to 100 ml with distilled water.
• Measure optical density at 420 nm against blank.
• Plot optical density vs. ferric oxide concentration (ppm).

Summary Table for Calibration

IS 12423: Sampling & Sample Preparation - Key Points

Sampling Mass (Clause 1.5)

• Sample mass: 1.5 to 2 g when chloride content is ~0.01%.

Preparation of Standard Stock Solution (Clause 7.4.2.2)

• Weigh 0.100 g quartz (<106 μm) + 2.5 g sodium carbonate + 1.0 g boric acid in platinum crucible.
• Mix, cover, heat:
  • Low flame: 10 min
  • At 1000°C: 20 min
• Cool, dissolve melt in 17.5 ml conc. HNO3 + 100 ml distilled water.
• Transfer to 1000 ml volumetric flask, dilute to mark → 100 ppm SiO2 stock solution.

Calibration (Clause 7.4.1.3)

• Pipette varying volumes (1-20 ml) of 200 ppm SiO2 into 100 ml flasks.
• Add blank solution accordingly.
• Add sequentially:
  a) 5 ml tartaric acid
  b) Water (~80 ml total volume)
  c) 5 ml acetone
  d) 10 ml ammonium molybdate reagent
• Incubate at 32±1°C for 10 min.
• Measure optical density at 410 nm after 15±2 min.
• Plot calibration curve: Optical density vs ppm SiO2.

Chloride Estimation (Clause 8.4.1.5)

• Weigh 0.50 g test sample, moisten, add 10 ml HNO3 (1:1), boil.
• Filter into 100 ml flask.
• Add sequentially:
  a) 10 ml saturated mercuric thiocyanate
  b) 5 ml ferric nitrate
• Make up volume, measure optical density at 460 nm after 5 min.
• Calculate % Chloride:

[ \text{Chloride, %} = \frac{\text{Concentration in ppm (from graph)} \times 50}{\text{Sample weight (g)}} ]

Summary Table

IS 12423: Reproducibility of Results – Key Formulas & Specifications

1. Rounding Off Results (Clause 0.3)

• Final test values must be rounded per IS 2-1960.
• Retain the same number of significant figures as specified in the standard.

2. Sample Preparation (Clause 2.1)

• Samples taken as per IS 3535-1986.
• Thorough mixing of representative cement samples before testing.

3. Calibration for Ferric Oxide (Fe₂O₃) (Clause 7.6.3)

4. Calibration for Titanium Dioxide (TiO₂) (Clause 8.1.3)

Summary Calibration Curve Plot

graph LR
A[Standard Solution Volume (ml)] --> B[Add Reagents]
B --> C[Make up to 100 ml]
C --> D[Measure Optical Density]
D --> E[Plot Optical Density vs Concentration (ppm)]

Note: Regularly verify calibration curves

IS 12423: Apparatus and Equipment Key Specifications & Calibration Procedures

1. Glassware

• Use only 'A' certified glassware for all measurements (Clause 4.3).

2. Calibration for Sulphate (Clause 7.9.5)

• Pipette volumes: 2.5, 5, 7.5, 12.5, 17.5, 20 ml (and twice these volumes for another set).
• Add reagents sequentially:
  • 10 ml dimethyl formamide
  • 15 ml stabilized barium chloride solution
• Make volume up to 100 ml with distilled water.
• Measure optical density at 502 nm using a 10 mm absorption cell after 5 min.
• Subtract reagent blank optical density.
• Plot calibration curve: Optical Density vs Sulphate concentration (ppm).

3. Calibration for Phosphorus Pentoxide (Clause 8.3.3)

• Pipette volumes: 0.5 to 10 ml of 200 ppm P₂O₅ solution.
• Add 25 ml ammonium vanadomolybdate solution, shake, and make volume to 100 ml.
• Extract with 10 ml amyl alcohol in separating funnel; shake 2 min, settle 5 min.
• Filter alcoholic layer, measure optical density at 426 nm against reagent blank.
• Plot calibration curve: Optical Density vs P₂O₅ concentration (ppm).

Notes:

• Always prepare reagent blanks similarly.
• Wash absorption cells with EDTA after sulphate measurements to prevent barium sulphate adherence.
• Round off values per IS 2-1960 for consistency.

flowchart TD
    A[Pipette Sample Volumes] --> B[Add Reagents]
    B --> C[Make up to 100 ml]
    C --> D[Measure Optical Density]
    D --> E[Subtract Blank OD]
    E --> F[Plot Calibration Curve]

This summarizes apparatus use and calibration for accurate chemical analysis per IS 12423.

IS 12423: Key Formulas & Specifications for Reagents and Special Solutions

1. General Requirements (Clause 6.1)

• Use analytical reagent grade chemicals.
• Use distilled water as per IS:1070-1977 for all aqueous reagents.

2. Preparation of Stock Solution A (Clause 7.3.1)

• Ingredients:

  • 2.5 g dry sodium hydroxide (NaOH)
  • 55 ml of 5 N HCl
  • Distilled water to 500 ml

• Procedure:

  1. Dissolve NaOH in distilled water.
  2. Add 55 ml of 5 N HCl.
  3. Transfer to 500 ml volumetric flask and fill to mark with distilled water.
  4. Label as Solution C.

3. Ammonium Molybdate Reagent (Clause 6.1.2.3)

• Two parts:

• Mixing:
  • Combine (a) and (b).
  • Make volume up to 400 ml.
  • Ensure pH = 1.5 to 1.7.
  • Store in plastic bottle.

Summary Table:

flowchart TD
    A[Start] --> B[Prepare Part (

Preparation of Stock and Standard Solutions (IS 12423)

Key Formulas & Specifications:

• Stock Solution A (Clause 7.3.1):

  • Dissolve 2.5 g NaOH in distilled water.
  • Add 55 ml of 5 N HCl.
  • Transfer to 500 ml volumetric flask and dilute to mark.
  • Label as Solution C (used for reagent blank).

• Standard Stock Silver Nitrate Solution (Clause 8.4.2.2):

  • Weigh 0.15751 g AgNO₃.
  • Dissolve and make up to 1 litre.
  • Result: 100 ppm silver solution.

• Standard Stock Solution with Calcium Oxide (Clause 7.9.3):

  • Take 100 ml of stock solution (from 7.9.2).
  • Add 3.5714 g pure CaCO₃.
  • Dissolve with dilute HCl until clear.
  • Make up to 1 litre with distilled water.

• Standard Stock Magnesium Sulphate Solution (Clause 7.8.2):

  • Dissolve 6.1151 g MgSO₄·7H₂O in distilled water.
  • Make up volume to 1 litre.
  • Concentration: 100 ppm magnesia.

Summary Table

IS 12423: Determination of Major Constituents (Clause 8.4.1.5)

Test Solution Preparation:

• Weigh 0.50 g of test sample.
• Moisten with water, add 10 ml HNO3 (1:1).
• Heat to boil for complete decomposition.
• Filter through Whatman No. 40 into a 100 ml flask.

Reagent Addition Sequence:

1. Add 10 ml saturated mercuric thiocyanate solution.
2. Add 5 ml ferric nitrate.
3. Make up volume to the mark (100 ml).

Measurement:

• Measure optical density at 460 nm after 5 minutes against reagent blank.

Chloride Percentage Calculation:

[ \text{Chloride, %} = \frac{\text{Concentration in ppm (from calibration graph)} \times 50}{1000} ]

(Since 0.5 g sample in 100 ml corresponds to factor 50)

Quality Control (Clause 3.1):

• Blank determinations on reagents mandatory.
• Check determinations repeated if difference exceeds:
  • 0.15% for silica and CaO,
  • 0.10% for other constituents,
  • 0.02% for chloride.

Summary Table:

This method ensures precise quantification of major constituents like chloride in cement samples.

IS 12423: Determination of Minor Constituents (Clause 7.9.6 & related)

Key Points & Procedure for Minor Constituents (e.g., Chloride):

• Sample Preparation (Clause 8.4.1.5):

  • Weigh 0.50 g of sample.
  • Moisten with water, add 10 ml HNO3 (1:1).
  • Heat to boiling for complete decomposition.
  • Filter into 100 ml volumetric flask.

• Reagent Addition:

  • Add 10 ml saturated mercuric thiocyanate solution.
  • Add 5 ml ferric nitrate.
  • Make volume up to 100 ml.

• Measurement:

  • Measure optical density at 460 nm after 5 minutes.
  • Use calibration graph to find concentration in ppm.

• Calculation:

[ \text{Chloride %} = \frac{\text{Concentration in ppm (from graph)} \times 50}{1000} ]

(Note: 50 = dilution factor based on sample weight and volume)

• Sample Mass Note (Clause 1.5):
  • Use 1.5 to 2 g sample if chloride content < 0.01%.

Summary Table for Chloride Estimation

flowchart TD
    A[Weigh 0.5 g sample] --> B[Moisten + Add 10 ml HNO3 (1:1)]
    B --> C[Heat to boil (decompose)]
    C --> D[Filter into 100 ml flask]
    D --> E[Add 10 ml mercuric thiocyanate]
    E --> F[Add 5 ml ferric nitrate]
    F --> G[Make

IS 12423 Calibration Procedures – Key Points & Formulas

Calibration involves preparing standard solutions, adding reagents, measuring optical density (OD), and plotting calibration curves (OD vs concentration).

1. Ferric Oxide Calibration (Clause 7.6.3)

• Pipette: 2, 4, 6, 8, 10, 12, 16 ml of 100 ppm Fe₂O₃ into 100 ml flasks.
• Add sequentially:
  • 5 ml ammonium chloride
  • 6 ml sulfosalicylic acid (10 ml for PPC)
• Add ammonia until color changes pink → bright yellow + 1 ml more ammonia.
• Make volume 100 ml with distilled water.
• Measure OD at 420 nm (10 mm cell) against blank.
• Plot OD vs ppm Fe₂O₃.

2. Phosphorus Pentoxide Calibration (Clause 8.3.3)

• Pipette: 0.5, 1, 2, 3, 4, 5, 6.5, 8, 9, 10 ml of 200 ppm P₂O₅ into 100 ml flasks.
• Add 25 ml ammonium vanadomolybdate, shake, make up volume.
• Extract with 10 ml amyl alcohol, filter, measure OD at 426 nm.
• Plot OD vs ppm P₂O₅ (1 to 20 ppm).

3. Alumina Calibration (Clause 7.5.3)

• Pipette: 0.5, 1, 2, 4, 6, 9 ml of solution F into 100 ml flasks.
• Add sequentially:
  • 2 ml ascorbic acid
  • 5 ml sodium phosphate, wait 5 min, add 50 ml distilled water
  • 5 ml buffer (pH 4.6)
  • 20 ml chrome azurole-S
• Wait 15 min, make volume 100 ml.
• Measure OD at 568 nm (10 mm cell).
• Net OD = OD(sample) - OD(blank).
• Plot net OD vs ppm alumina.

4. Sulphate Calibration (Clause 7.9.5)

• Pip

IS 12423: Test Procedures & Estimations - Key Points

1. Rounding Off Results (Clause 0.3)

• Final test/analysis values rounded per IS 2-1960.
• Retain significant figures same as specified values.

2. Calibration Procedures

• Prepare blank with distilled water + reagents.
• Plot Optical Density (OD) vs. concentration (ppm) to get calibration curve.
• Recalibrate regularly or when reagents are freshly prepared.
• Wash absorption cell with EDTA after sulphate tests.

3. Estimation of Titanium Dioxide (Clause 8.1.4)

• Treat 1 g sample with 20 ml conc. HCl, boil, dilute, filter silica.
• Fuse residue with 1:1 borax + sodium carbonate, dissolve in HCl.
• Combine filtrate + fused solution.
• Precipitate R2O3 by adding methyl red + ammonium chloride.
• Precipitate hydroxides with 1:2 ammonia till solution turns yellow.
• Filter, wash (distilled water + hot 1:3 H2SO4), collect washings in 100 ml flask.
• Add reagents (as in 8.1.3), make volume 100 ml.
• Measure OD at 410 nm against blank.
• Calculate % TiO2:

\

IS 12423: Quality Control & Blank Determinations

Key Points from Clauses:

1. Preparation of Blank Solution (Clause 7.3 & 8.4.1.3)

• Prepare blank by adding reagents in the same order as test solutions but without the analyte.
• For calibration, use distilled water with reagents:
  • 5 ml ammonium chloride
  • 6 ml sulphosalicylic acid (10 ml for PPC)
  • Ammonia till color changes from pink to bright yellow + 1 ml extra
• Volume made up to 100 ml with distilled water.
• Composite blank solution for calibration includes:
  • 15,000 ppm CaO
  • 875 ppm Fe2O3
  • 1,500 ppm Al2O3
  • 500 ppm MgO (in 500 ml flask)

2. Calibration Curve (Clause 7.6.3)

• Pipette volumes of 2, 4, 6, 8, 10, 12, 16 ml of 100 ppm ferric oxide into 100 ml flasks.
• Add reagents as above.
• Measure optical density at 420 nm against blank using 10 mm cell.
• Plot optical density vs. concentration (ppm Fe2O3).

3. Blank Determinations & Tolerances (Clause 3.1)

• Blank determinations must be made on reagents for each cement constituent.
• Corrections applied where necessary.
• Check determinations repeated if difference exceeds:
  • Silica & CaO: ±0.15%
  • Other constituents: ±0.1%
  • Chloride: ±0.02%

Summary Table: Blank Solution Concentrations

Calibration Curve Sketch

graph LR
A[Volume of Fe2O3 solution (ml)] --> B[Optical Density at 420 nm]
B --> C[Plot Calibration Curve]

**Use blank solutions to correct absorbance

IS 12423: Calculation of Results — Key Specifications & Calibration Procedures

1. Rounding Off Results (Clause 0.3)

   • Final test/analysis values must be rounded per IS 2-1960.
   • Retain the same number of significant digits as the specified standard value.

2. Calibration Curves for Different Constituents:

3. General Calibration Curve Preparation:
   • Plot Optical Density (OD) vs. **Concentration (ppm

IS 12423 - Interference and Masking Techniques

Key Points from IS 12423:

• Interference Sources: Silica, manganese, iron, aluminium, calcium affect optical density measurements.
• Masking Agents:
  • Silica (up to 30%): Masked by dimethyl formamide.
  • Manganese: Masked by reducing agents like hydroxylamine hydrochloride.
  • Iron, Aluminium, Calcium: Accounted by adding equal amounts in both sample and standards.

Calibration (Clause 8.4.2.3):

• Prepare silver solutions (1-10 ppm).
• Add NH₄OH and sodium sulphide.
• Measure optical density against reagent blank.

Measurement with Brilliant Yellow (Clause 7.8.1):

• Forms scarlet lake with magnesium in alkaline medium.
• Measure optical density at 550 nm after 1-2 minutes.
• Stability of colloidal suspension ~10 min.

Summary Table for Masking Agents

flowchart LR
    A[Sample Solution] --> B[Add Reagents]
    B --> C{Interference?}
    C -->|Silica| D[Add Dimethyl Formamide]
    C -->|Manganese| E[Add Hydroxylamine Hydrochloride]
    C -->|Fe, Al, Ca| F[Add same ions in standards]
    D & E & F --> G[Measure Optical Density]

Note: Follow IS 2-1960 for rounding off results as per specified significant figures.

IS 12423 (1988) primarily covers specifications for sulphuric acid, but does not explicitly detail Safety and Handling Precautions in the clauses provided.

General Safety & Handling Guidelines for Sulphuric Acid (sp gr 1.84):

• Personal Protective Equipment (PPE): Use acid-resistant gloves, goggles, face shield, and protective clothing.
• Storage: Store in cool, well-ventilated areas away from incompatible materials (e.g., organic matter, bases).
• Handling: Use corrosion-resistant containers and tools; avoid spills and splashes.
• Emergency Measures: Have neutralizing agents (e.g., sodium bicarbonate) and eyewash stations nearby.

Rounding Off Values (IS 2-1960):

• Round off test results to the same number of significant figures as specified in the standard.
• Example: If standard specifies 3 significant figures, round 1.8432 to 1.84.

Summary Table: Sulphuric Acid Properties (IS 266-1977)

flowchart LR
    A[Storage] --> B[Cool, ventilated area]
    A --> C[Away from organics/bases]
    D[Handling] --> E[PPE: Gloves, goggles]
    D --> F[Use corrosion-resistant tools]
    G[Emergency] --> H[Neutralizing agents]
    G --> I[Eyewash stations]

For detailed safety, refer to IS 266 and relevant chemical safety standards.

IS 12423 - 1988: References and Related Standards

• Rounding Off Numerical Values:
  As per IS 2:1960, all test or analysis results must be rounded off to the same number of significant digits as the specified value in IS 12423.

• Chemical Analysis of Hydraulic Cement:
  Refer IS 4031 (First Revision) for methods of chemical analysis related to hydraulic cement.

• General Specifications:
  IS 12423 (1988) was reaffirmed in 2005, ensuring continued relevance.

Key Points:

This ensures uniformity in reporting and testing cement properties under IS 12423.

flowchart LR
    A[IS 12423 Testing] --> B[Rounding off values]
    B --> C[IS 2:1960]
    A --> D[Chemical Analysis]
    D --> E[IS 4031]