Methods of Test for Aggregates for Concrete, Part VII: Alkali Aggregate Reactivity

IS 2386 Part 7: Scope - Key Specifications & Tables

a) Scales:

• Permissible variation at 2000 g load: ±2.0 g (in use)
• New scales: half of above → ±1.0 g
• Sensibility reciprocal ≤ 2 × permissible variation

b) Weights:

c) Balances:

• Capacity ≥ 100 g per pan
• Beam arms equal within 2/100,000 (in use) or 1/100,000 (new)
• Reproducibility: ±0.0002 g
• Sensibility reciprocal ≤ 0.0005 g/division (up to 100 g load)
• Rapid weighing devices error ≤ 0.0001 g

d) Crushing & Grinding:

• Equipment to crush ~4 kg aggregate to pass 300-micron sieve

e) Sieves:

• 300-micron and 150-micron square-hole woven wire cloth (IS:460-1962)

f) Reaction Containers:

IS 2386 Part 7: Selection and Preparation of Materials

Key Points from Clauses 2.4 & 2.5

• Cement Selection (Clause 2.4.3):

  • Cement must comply with IS 269-1958 (Ordinary, Rapid-Hardening, Low Heat Portland Cement).
  • Cement should be from the project-approved source.
  • Cement must be passed through an 850-micron IS sieve to remove lumps.
  • Test cements with alkali content > 0.60% (Na₂O + 0.658 × K₂O) should be included.
  • Use both high-alkali and low-alkali Portland cements with aggregates for testing.

• Grading Requirements (Table from Clause 2.4.2):

• Preparation of Test Specimens (Clause 2.5 & 3.5):
  • Samples should be representative and prepared as per project specifications.
  • Aggregate samples must be dried and sieved according to grading requirements.
  • Cement and aggregates must be mixed uniformly before testing.

Alkali Content Formula

[ \text{Alkali content} = % \text{Na}_2\text{O} + 0.658 \times % \text{K}_2\text{O} ]

This ensures proper material selection and preparation for reliable testing results per IS 2386 Part 7.

IS 2386 Part 7 - Apparatus Specifications & Key Formulas

1. Scales

• Permissible variation at 2000 g load: ±2.0 g (in-use), half for new scales.
• Sensibility reciprocal: ≤ 2 × permissible variation.

2. Weights

• Permissible variations as per Table I (not provided here).
• New weights: half the permissible variation of in-use weights.

3. Balances (for dissolved silica gravimetric method)

• Capacity: ≥ 100 g per pan.
• Beam arms equal within:
  • 2 parts in 100,000 (in-use)
  • 1 part in 100,000 (new)
• Reproducibility: within 0.0002 g.
• Sensibility reciprocal: ≤ 0.0005 g/division for loads ≤ 100 g.
• Rapid weighing devices must not introduce errors > 0.0001 g.

4. Crushing & Grinding

• Equipment to crush ~4 kg aggregate to pass a 300-micron IS sieve.

5. Sieves

• 300-micron and 150-micron square-hole woven wire cloth sieves conforming to IS 460-1962.

6. Reaction Containers

• Capacity: 50-75 ml, stainless steel or corrosion-resistant, airtight covers.

7. Constant-Temperature Bath

• Maintain 80 ± 1°C for 24 hours.

8. Photometer

• Photoelectric, measuring light transmission at ~410 nm wavelength.

Summary Table (Key Parameters)

flowchart

IS 2386 Part 7: Preparation of Test Specimens — Key Specifications

1. Mould and Gauge Studs (Clause 2.5)

• Gauge studs: Extend 15.0 ± 0.5 mm into specimen.
• Distance between inner ends of gauge studs: 250 ± 2.5 mm.
• Mould compartment width & height: 25 ± 0.75 mm.
• Moulds: Single and double types with knurled/threaded gauge studs (see Fig. 1).
• Note: Stainless steel gauge studs may corrode under test conditions.

2. Tamper (Clause 12.5 g)

• Material: Non-absorptive, non-abrasive (medium-hard rubber or seasoned oak wood treated with paraffin at ~200℃ for 15 min).
• Cross-section: 12.5 × 25 mm.
• Length: Convenient, typically 125 or 150 mm.
• Tamp face: Flat, perpendicular to length.

3. Trowel (Clause 12.5 h)

• Steel blade, length 100 to 150 mm, straight edges.

4. Containers (Clause 12.5 j)

• Corrosion-resistant material.
• Tight-fitting covers to prevent moisture loss.
• Specimens supported vertically, lower end ~25 mm above water surface.
• Specimens must not touch container sides or each other.
• Prevent water splashing and condensate dripping.

5. Length Comparator (Clause 12.5 k)

• Positive contact with gauge stud for reproducible length measurement.
• Dial micrometer with:
  • Graduation: 0.002 mm.
  • Accuracy: ±0.002 mm (0.02 mm range), ±0.004 mm (0.25 mm range).
• Sufficient range for variations in gauge length.

Summary Table: Key Dimensions

IS 2386 (Part 7) - Key Specifications for Storage & Measurement of Specimens

Storage Conditions

• Storage room temperature: 38°C ± 2°C (Clause 2.3.3)
• Specimen container temperature: 60°C ± 2°C in metal containers (Clause 2.11.1)

Weighing Equipment

• Permissible scale variation:
  • In use: ±2.0 g at 2000 g load
  • New scales: ±1.0 g (half of above)
• Weight tolerances: See Table I (values halved for new weights)
• Analytical balance specs:
  • Capacity ≥ 100 g per pan
  • Beam arm equality: 2 parts in 100,000 (in use), 1 part in 100,000 (new)
  • Reproducibility: ±0.0002 g
  • Sensibility reciprocal ≤ 0.0005 g/division (up to 100 g load)
  • Rapid weighing aids error ≤ 0.0001 g

Equipment & Materials

• Crushing & grinding: Jaw crusher + disc pulverizer for ~4 kg aggregate to pass 300-micron sieve
• Sieves: 300-micron & 150-micron woven wire cloth (IS 460-1962)
• Reaction containers: Stainless steel, 50-75 ml, airtight covers
• Constant temperature bath: 80°C ± 1°C for 24 h
• Photometer: Measures light transmission at ~410 nm wavelength

Table I: Permissible Variation on Weights (Example)

Note: Values halved for new weights.

flowchart LR
    A[Specimen Collection] --> B[Storage in Metal Container]
    B -->|60±2°C| C[Measurement]
    C -->

IS 2386 Part 7: Chemical Test Procedure - Key Specifications & Formulas

Equipment & Materials

• Scales:
  • Load 2000 g: ±2.0 g variation (new scales ±1.0 g)
  • Sensibility reciprocal ≤ 2 × permissible variation
• Weights:
  • Permissible variations as per Table I (new weights have half the variation)
• Balances (for dissolved silica):
  • Capacity ≥ 100 g per pan
  • Beam arm equality: 2 parts/100,000 (in use), 1 part/100,000 (new)
  • Reproducibility: ±0.0002 g
  • Sensibility reciprocal ≤ 0.0005 g/division (up to 100 g load)
• Crushing & Grinding:
  • Jaw crusher + disc pulverizer for ~4 kg aggregate to pass 300-micron sieve
• Sieves:
  • 300-micron and 150-micron IS 460-1962 compliant
• Reaction Containers:
  • 50–75 ml stainless steel with airtight covers
• Constant-Temperature Bath:
  • Maintain 80 ±1℃ for 24 h
• Photometer:
  • Measures light transmission at ~410 nm wavelength

Chemical Reagents

• Caustic Soda Solution: 1.000 N
• Concentrated Sulphuric Acid: sp gr 1.84
• Hydrochloric Acid: sp gr 1.19 (used in evaporation and digestion steps)

Test Procedure Highlights

• Weigh 3 × 25.00 ± 0.05 g samples (300 to 150 micron fraction).
• Add 25 ml 1.000 N caustic soda to each; one container as blank.
• Seal and swirl to remove trapped air.
• Evaporate 100 ml dilute solution with 5–10 ml HCl (sp gr 1.19) to dryness on steam bath 3 times.
• Digest residue with HCl (1:1), dilute with hot water, filter, and wash silica thoroughly.

Table I (Permissible Weight Variations)

|

IS 2386 Part 7: Determination of Dissolved Silica (Photometric Method)

Key Steps & Formulas (Clause 3.8)

1. Preparation of Calibration Curve (3.8.3.1):

   • Prepare silica standard solutions (0.0 to 0.5 mmol/L) by diluting sodium silicate stock.
   • To 100 ml volumetric flask (~50 ml water), add:
     • Known aliquot of sodium silicate solution
     • 2 ml ammonium molybdate solution
     • 1 ml hydrochloric acid (1:1)
   • Swirl and stand for 15 minutes at room temperature.
   • Add 1.5 ± 0.2 ml oxalic acid solution.
   • Fill to mark with water, mix, and stand for 5 ± 0.1 minutes.
   • Measure light transmission at specified wavelength.

2. Measurement of Sample (3.8.4):

   • Transfer 10 ml aliquot of diluted sample to 100 ml volumetric flask.
   • Follow same reagent addition and timing as calibration.
   • Read silica concentration directly from calibration curve.
   • Adjust aliquot size if transmittance <30% or >50%.

Summary Table for Reagents & Timings

Notes:

• Calibration curve correlates light transmission (%) with silica concentration (mmol/L).
• Use aliquot adjustment to maintain transmittance in 30-50% range for accuracy.

flowchart TD
    A[Prepare Sodium Silicate Standards] --> B[Add Ammonium Molyb

IS 2386 (Part 7) - Interpretation of Results: Key Points

1. Permissible Variations & Sensibility

• Load 2000 g on scales: ±2.0 g variation allowed; new scales ±1.0 g.
• Weights in use: Permissible variations as per Table I (values halved for new weights).
• Sensibility reciprocal: ≤ 2 × permissible variation.
• Balances:
  • Capacity ≥ 100 g per pan.
  • Beam arms equal within 2/100,000 (in use) or 1/100,000 (new).
  • Reproducibility: ±0.0002 g.
  • Sensibility reciprocal ≤ 0.0005 g/division up to 100 g load.
  • Rapid weighing devices error ≤ 0.0001 g.

2. Equipment Specifications

• Crushing/Grinding: Equipment to reduce ~4 kg aggregate to pass 300-micron sieve.
• Sieves: 300 & 150-micron woven wire cloth (IS 460-1962).
• Reaction Containers: 50-75 ml, stainless steel, airtight.
• Constant Temp Bath: 80 ±1℃ for 24 h.
• Photometer: Measures light transmission at ~410 nm.

3. Reporting Results (Clause 2.9)

Include:

• Aggregate & cement type/source.
• Cement alkali content (% K2O, Na2O, Na2O eq.).
• Average length change (%).
• Aggregate grading details.
• Specimen examination features.
• Mixing water % by cement weight.
• Pozzolana details and chemical analysis.

4. Rounding Off (Clause 0.5)

• Follow IS 2-1960 rules.
• Retain significant digits as per specified values.

Table I (Permissible Variations on Weights in Use) - Summary

IS 2386 Part 7 — Repeatability and Accuracy Key Points

1. Calibration & Error Correction (Clause 12.5 Note 2)

• Calibrate micrometers/measuring devices across their range.
• Determine periodic and cumulative errors.
• Apply corrections to observed data for accuracy.

2. Permissible Variation on Scales (Clause 2.0)

• For scales in use at 2000 g load: ±2.0 g variation allowed.
• For new scales: variation should be half (±1.0 g).
• Sensibility reciprocal ≤ 2 × permissible variation.

3. Weights Permissible Variations (Table I)

• For new weights, permissible variation is half the above.

4. Balances (Clause c)

• Capacity ≥ 100 g per pan.
• Beam arms equal within:
  • 2 parts in 100,000 (in use),
  • 1 part in 100,000 (new).
• Reproducibility: ±0.0002 g.
• Sensibility reciprocal ≤ 0.0005 g/division for loads ≤ 100 g.
• Rapid weighing devices must not introduce errors > 0.0001 g.

Sensibility Reciprocal Definition:

Weight required to move the pointer by one scale division.

This ensures high precision and repeatability in gravimetric tests per IS 2386 Part 7 standards.

IS 2386 Part 7: Notes on Testing Conditions – Key Specifications

• Tamper (Clause 12.5 g):

  • Material: Non-absorptive, non-abrasive (medium-hard rubber or seasoned oak wood paraffin-treated at ~200℃ for 15 min)
  • Cross-section: 12.5 mm × 25 mm
  • Length: 125 or 150 mm
  • Tamping face: Flat, perpendicular to length

• Trowel (Clause 12.5 h):

  • Steel blade, length 100–150 mm, straight edges

• Containers (Clause 12.5 j):

  • Corrosion-resistant with tight-fitting covers to prevent moisture loss
  • Specimens supported vertically, 25 mm above water surface
  • Specimens must not touch container sides or each other
  • Prevent water splashing and condensate dripping

• Length Comparator (Clause 12.5 k):

  • Contact: Positive, reproducible with gauge stud
  • Measuring device: Dial micrometer, graduation 0.002 mm
  • Accuracy: ±0.002 mm (0.02 mm range), ±0.004 mm (0.25 mm range)
  • Range: Sufficient for gauge length variations

• Scales and Weights (Clause 2.0 & b):

  • Permissible variation at 2000 g load: ±2.0 g (in-use), half for new scales
  • Weights variation as per Table I (not provided here)

• Balances (Clause 2.0 c):

  • Capacity ≥100 g per pan
  • Beam arms equal within 2 parts in 100,000 (in use)
  • Reproducibility: 0.0002 g
  • Sensibility reciprocal ≤0.0005 g/division up to 100 g

• Other Equipment:

  • Crushing/grinding: Jaw crusher + disc pulverizer for 4 kg to pass 300-micron sieve
  • Sieves: 300-micron & 150-micron woven wire cloth (IS 460-1962)
  • Reaction containers: 50–75 ml, stainless steel, airtight
  • Constant-temperature bath: 80 ±1℃ for 24 h
  • Photometer: Measures light transmission at

IS 2386 Part 7 primarily covers testing of concrete aggregates, with key references and specifications as follows:

Key Specifications:

• Reference to ASTM Standards: ASTM standards are used as supplementary guidance for test methods.
• Rounding Off (IS 2-1960):
  • Results must be rounded off according to IS 2-1960 rules.
  • Retain the same number of significant digits as the specified value in IS 2386.
• Latest Standards:
  • Any referenced Indian Standard should be interpreted as the latest version.

Important Notes:

• IS 2386 Part 7 does not cover contract provisions—focuses solely on technical testing.
• For detailed testing procedures, refer to the latest versions of referenced IS and ASTM standards.

Summary Table for Rounding (IS 2-1960):

flowchart LR
    A[IS 2386 Part 7 Testing] --> B[Refer ASTM Standards]
    A --> C[Use IS 2-1960 for Rounding]
    A --> D[Refer Latest IS Versions]
    B --> E[Supplementary Guidance]
    C --> F[Maintain Specified Precision]

This ensures consistency and compliance across testing and reporting of aggregate properties.

IS 2386 Part 7 — Annexure: Mould and Apparatus Details

Key Specifications & Dimensions

Dimensional Summary (mm)

Mould Assembly (Simplified Diagram)